Patent Publication Number: US-2023157814-A1

Title: Multi-portion replacement heart valve prosthesis

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Application No. 17/980,384, filed Nov. 3, 2022, which is a continuation of U.S. Application No. 16/843,122, filed Apr. 8, 2020, now U.S. Pat. No. 11,504,229, which is a continuation of U.S. Application No. 15/687,184, filed Aug. 25, 2017, now U.S. Pat. No. 10,639,143, which claims the benefit of U.S. Provisional Application No. 62/380,061 filed Aug. 26, 2016, each of which is incorporated herein by reference in its entirety and is to be considered a part of this specification. 
    
    
     BACKGROUND 
     Field 
     Certain embodiments disclosed herein relate generally to prostheses for implantation within a lumen or body cavity. In particular, certain embodiments relate to expandable prostheses such as replacement heart valves, such as for the mitral valve, that are configured to be secured to intralumenal tissue and prevent paravalvular leakage. 
     Background 
     Human heart valves, which include the aortic, pulmonary, mitral and tricuspid valves, function essentially as one-way valves operating in synchronization with the pumping heart. The valves allow blood to flow downstream, but block blood from flowing upstream. Diseased heart valves exhibit impairments such as narrowing of the valve or regurgitation, which inhibit the valves’ ability to control blood flow. Such impairments reduce the heart’s blood-pumping efficiency and can be a debilitating and life threatening condition. For example, valve insufficiency can lead to conditions such as heart hypertrophy and dilation of the ventricle. Thus, extensive efforts have been made to develop methods and apparatuses to repair or replace impaired heart valves. 
     Prostheses exist to correct problems associated with impaired heart valves. For example, mechanical and tissue-based heart valve prostheses can be used to replace impaired native heart valves. More recently, substantial effort has been dedicated to developing replacement heart valves, particularly tissue-based replacement heart valves that can be delivered with less trauma to the patient than through open heart surgery. Replacement valves are being designed to be delivered through minimally invasive procedures and even percutaneous procedures. Such replacement valves often include a tissue-based valve body that is connected to an expandable frame that is then delivered to the native valve’s annulus. 
     These replacement valves are often intended to at least partially block blood flow. However, a problem occurs when blood flows around the valve on the outside of the prosthesis. For example, in the context of replacement heart valves, paravalvular leakage has proven particularly challenging. An additional challenge relates to the ability of such prostheses to be secured relative to intralumenal tissue, e.g., tissue within any body lumen or cavity, in an atraumatic manner. Yet another challenge arises when trying to reduce the likelihood of thrombosis within parts of the replacement valves. 
     SUMMARY 
     Embodiments of the present disclosure are directed to a prosthesis, such as but not limited to a replacement heart valve. 
     In some embodiments, a replacement heart valve prosthesis can include an expandable frame. The expandable frame can radially expand and contract for deployment within a native heart valve. The expandable frame can have a longitudinal axis between upper and lower ends. The expandable frame can include a first frame portion. The first frame portion can include a first frame body. The first frame body can include a first upper region, a first intermediate region, and/or a first lower region. The first frame portion can include a first anchoring feature. When the prosthesis is in an expanded configuration, the first anchoring feature can extend radially outwardly from the first lower region and/or at least a portion of the first anchoring feature can extend towards the first upper region. 
     The expandable frame can include a second frame portion positioned radially outward of the first frame body. The second frame portion can include a second frame body. The second frame body can include a second upper region, a second intermediate region, and/or a second lower region. When the prosthesis is in an expanded configuration, at least a portion of the second upper region can extend radially outwardly from the first upper region and/or the second lower region can be positioned radially between the first anchoring feature and the first frame body. When the prosthesis is in an expanded configuration and deployed within the native heart valve, the second intermediate portion can be positioned within a native valve annulus. 
     The replacement heart valve prosthesis can include a valve body positioned within an interior of the first frame portion. The valve body can include a plurality of leaflets which can allow flow in a first direction and prevent flow in a second opposite direction. 
     When the prosthesis is in an expanded configuration, the second intermediate region can be generally cylindrical. When the prosthesis is in an expanded configuration, the second intermediate region can be generally non-cylindrical. When the prosthesis is in an expanded configuration, a portion of the second intermediate region between the upper and lower ends of the second intermediate region can have a diameter greater than at least one of the upper and lower ends of the second intermediate region. The second intermediate region can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, the second intermediate region can exert a radially outward force on the native valve annulus. When the prosthesis is in an expanded configuration, the second lower region can be inclined and/or curved radially inward towards the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of the second upper region can extend towards the first lower region. When the prosthesis is in an expanded configuration, at least a portion of the second upper region can extend towards the first lower region in a direction generally parallel to the longitudinal axis. The second frame portion and the first anchoring feature can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, native valve leaflets and/or the native valve annulus can be pinched between the second frame portion and the first anchoring feature. 
     When the prosthesis is in an expanded configuration, at least a portion of the first anchoring feature can extend upwards towards the first upper region. The first anchoring feature can include a first plurality of anchors. When the prosthesis is in an expanded configuration, tips of anchors of the first plurality of anchors can extend in a direction generally parallel to the longitudinal axis. When the prosthesis is in an expanded configuration, tips of anchors of the first plurality of anchors can extend in a direction generally perpendicular to the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of tips of anchors of the first plurality of anchors can extend radially inwardly towards the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of tips of anchors of the first plurality of anchors extend radially outwardly away from the longitudinal axis. When the prosthesis is deployed and expanded within a native mitral valve, at least some of the anchors of the first plurality of anchors can contact a native mitral valve annulus on a ventricular side. When the prosthesis is in an expanded configuration, at least a portion of anchors of the first plurality of anchors is angled in a circumferential direction and/or curved in a circumferential direction. 
     The second frame portion can include a second anchoring feature. At least a portion of the second anchoring feature can extend from at least one of the second upper region and the second intermediate region. The second anchoring feature can include a second plurality of anchors. Anchors of the second plurality of anchors can be V-shaped. When the prosthesis is in an expanded configuration, anchors of the second plurality of anchors can extend in a direction generally parallel to the second upper region. When the prosthesis transitions from an expanded configuration to a collapsed configuration, ends of the anchors of the second plurality of anchors can move radially outwardly and upwardly. When the prosthesis transitions from an expanded configuration to a collapsed configuration, ends of the anchors of the second plurality of anchors can move radially outwardly and downwardly. 
     The prosthesis can include a skirt extending around at least a portion of the prosthesis. At least a portion of the skirt can extend along an exterior of the second frame portion. At least a portion of the skirt can extend along an interior of the second frame portion. At least a portion of the skirt can extend along an interior of the second frame portion is attached to the valve body. At least a portion of the skirt can extend along an exterior of the second intermediate region. At least a portion of the skirt can extend along an exterior of the second upper region. At least a portion of the skirt can extend along an interior of the second upper region. At least a portion of the skirt is spaced apart from the second upper region. 
     The valve body can include a liner. The liner can extend from an arcuate edge of the plurality of leaflets towards an upper end of the first frame body. An upper end of the liner can be positioned at or proximate an upper end of the first frame body. An upper end of the liner can be positioned at or proximate an uppermost end of an arcuate edge of the plurality of leaflets. 
     The valve body can include one or more intermediate components. The one or more intermediate components can be positioned between the first frame body and the valve leaflets. 
     The first frame portion and the second frame portion can be separate components. The first frame portion can include a plurality of first eyelets. The second frame portion can include a plurality of second eyelets. Each of the plurality of first eyelets can correspond with each of the plurality of second eyelets. The first frame portion and the second frame portion can be coupled at each of the plurality of first and second eyelets. The first and second frame portions can be tautly secured at one or more attachment points such that relative movement at the one or more attachment points is inhibited. The first and second frame portions can be loosely secured at one or more attachment points such that the first and second frame portions are movable relative to each other at the one or more attachment points. The first and second frame portions can be coupled via the skirt. 
     The inner frame portion and the outer frame portion form a monolithic component. 
     The first frame body can include one or more rows of cells. At least one row of cells can include an upper and lower portion formed from a plurality of undulating struts and a middle portion formed from one or more eyelets. The first frame body can include a foreshortening portion. The second frame body can include one or more rows of cells. The second frame body can include a foreshortening portion. One or more portions of the first frame body can form a cylindrical shape, a bulbous shape, and/or a frustoconical shape. 
     In some embodiments, a replacement heart valve prosthesis can include an expandable frame. The expandable frame can radially expand and contract for deployment within a native heart valve. The expandable frame can have a longitudinal axis between upper and lower ends. The expandable frame can include a frame body. The frame body can include an upper region, an intermediate region, and/or a lower region. 
     The expandable frame can include an upper anchoring feature, an intermediate anchoring feature, and/or a lower anchoring feature. The upper anchoring feature can extend from the upper region of the frame body. The intermediate anchoring feature can extend from the intermediate region of the frame body. The lower anchoring feature can extend from the lower region of the frame body. When the frame is in an expanded configuration, at least a portion of the upper anchoring feature can be positioned radially outward of the frame body, at least a portion of the intermediate anchoring feature can be positioned radially outward of the frame body, and/or at least a portion of the lower anchoring feature can be positioned radially outward of the frame body. 
     The replacement heart valve prosthesis can include a valve body positioned within an interior of the first frame portion. The valve body can include a plurality of leaflets which can allow flow in a first direction and prevent flow in a second opposite direction. 
     The intermediate anchoring feature can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, the second anchoring feature exerts a radially outward force on a native valve annulus. When the prosthesis is in an expanded configuration, at least a portion of the intermediate anchoring feature can be positioned radially between the frame body and the lower anchoring feature. The intermediate anchoring feature and the lower anchoring feature can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, native valve leaflets and/or a native valve annulus can be pinched between the intermediate anchoring feature and the lower anchoring feature. The intermediate anchoring feature can include a braided mesh. 
     The frame body and the intermediate anchoring feature can be separate components. The frame body and the intermediate anchoring feature can form a monolithic component. 
     When the prosthesis is in an expanded configuration, at least a portion of the upper anchoring feature can extend radially outward away from the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of the upper anchoring feature can extend radially inward towards the longitudinal axis. The upper anchoring feature can include an upper plurality of anchors. 
     When the prosthesis is in an expanded configuration, at least a portion of the lower anchoring feature can extend radially outward away from the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of the lower anchoring feature can extend upwardly towards the upper anchoring feature. The lower anchoring feature can be attached to the frame body above a lower end of the lower region. The lower anchoring feature can include a lower plurality of anchors. When the prosthesis is in an expanded configuration, tips of anchors of the lower plurality of anchors extend in a direction generally parallel to the longitudinal axis. When the prosthesis is in an expanded configuration, tips of anchors of the lower plurality of anchors can extend in a direction generally perpendicular to the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of tips of anchors of the lower plurality of anchors can extend radially inwardly towards the longitudinal axis. When the prosthesis is in an expanded configuration, at least a portion of tips of anchors of the lower plurality of anchors can extend radially outwardly away from the longitudinal axis. Anchors of the lower plurality of anchors can be sized such that, when the prosthesis is deployed and expanded within a native mitral valve, at least some of the anchors of the lower plurality of anchors can contact a native mitral valve annulus on a ventricular side. At least a portion of anchors of the lower plurality of anchors can be angled in a circumferential direction and/or curved in a circumferential direction. 
     The replacement heart valve prosthesis can include a skirt extending around at least a portion of the prosthesis. At least a portion of the skirt can extend radially outward of an exterior of the upper anchoring feature. At least a portion of the skirt can extend radially inward of an interior of the upper anchoring feature. At least a portion of the skirt can extend radially outward of an exterior of the intermediate anchoring feature. At least a portion of the skirt can extend between the intermediate anchoring feature and the lower anchoring feature. At least a portion of the skirt can be coupled to the upper region of the frame. At least a portion of the skirt can be coupled to the frame below the intermediate anchoring feature and above the lower anchoring feature. At least a portion of the skirt can be coupled to the valve body. At least a portion of the skirt can be coupled to a liner of the valve body. 
     The frame body can include one or more rows of cells. The first frame body can include a foreshortening portion. 
     In some embodiments, a replacement heart valve prosthesis can include an expandable frame. The expandable frame can radially expand and contract for deployment within a native heart valve. The expandable frame can have a longitudinal axis between upper and lower ends. The expandable frame can include a frame body. The frame body can include an upper region, an intermediate region, and/or a lower region. The expandable frame can include an anchoring feature. The anchoring feature can extend from the upper region of the frame body. The upper anchoring feature can include an anchor body formed from a wire mesh. When the prosthesis is in an expanded configuration, at least a portion of the anchor body can extend radially outwardly of the frame body. 
     The anchor body can be formed from a braided tube. The anchor body can conform to the shape of the native heart valve. When the prosthesis is deployed and expanded within a native mitral valve, at least a portion of the anchor body can be positioned intra-annularly and can exert a radially outward force on a native mitral valve annulus. When the prosthesis is deployed and expanded within a native mitral valve, at least a portion of the anchor body can be positioned in a left atrium and can extend overs an atrial surface of a native valve annulus. When the prosthesis is deployed and expanded within a native mitral valve, at least a portion of the anchor body can be positioned in a left ventricle and can exert a radial outward force on native leaflets. The anchoring feature can include one or more barbs. 
     The anchoring feature can include one or more arms extending from the upper region of the frame body and/or the anchor body. The one or more arms can be formed from a wire mesh. When the prosthesis is in an expanded configuration, the one or more arms can extend radially outwardly from the frame body. When the prosthesis is in an expanded configuration, the one or more arms can extend upwardly away from the frame body. When the prosthesis is deployed and expanded within a native mitral valve, the one or more arms can contact portions of an atrial wall. 
     In some embodiments, a replacement heart valve prosthesis can include an expandable frame. The expandable frame can radially expand and contract for deployment within a native heart valve. The expandable frame can have a longitudinal axis between upper and lower ends. The expandable frame can include a first frame portion. The first frame portion can include a first frame body. The first frame body can include a first upper region, a first intermediate region, and/or a first lower region. The first frame portion can include a first anchoring feature. When the prosthesis is in an expanded configuration, the first anchoring feature can be attached to the first frame body at a base along the first distal region and/or at least a portion of the first anchoring feature can extend towards the first upper region. 
     The expandable frame can include a second frame portion positioned radially outward of the first frame body. The second frame portion can include a second frame body. The second frame body can include a second upper region, a second intermediate region, and/or a second lower region. When the prosthesis is in an expanded configuration, at least a portion of the second lower region is positioned below the base, at least a portion of the second lower region is positioned radially between the first anchoring feature, and/or the second lower region extends radially outwardly from the first lower region. When the prosthesis is in an expanded configuration and deployed within the native heart valve, the second intermediate portion can be positioned within a native valve annulus. 
     The replacement heart valve prosthesis can include a valve body positioned within an interior of the first frame portion. The valve body can include a plurality of leaflets which can allow flow in a first direction and prevent flow in a second opposite direction. 
     When the prosthesis is in an expanded configuration, the second intermediate region can be generally cylindrical. When the prosthesis is in an expanded configuration, the second intermediate region is generally non-cylindrical. The second intermediate region can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, the second intermediate region exerts a radially outward force on the native valve annulus. The second frame portion and the first anchoring feature can be sized such that, when the prosthesis is deployed and expanded within the native heart valve, at least one of native valve leaflets and the native valve annulus are pinched between the second frame portion and the first anchoring feature. 
     The first anchoring feature can include a first plurality of anchors. When the prosthesis is in an expanded configuration, tips of anchors of the first plurality of anchors can extend in a direction generally parallel to the longitudinal axis. The first plurality of anchors can be sized such that, when the prosthesis is deployed and expanded within a native mitral valve, at least some of the anchors of the first plurality of anchors contact a native mitral valve annulus on a ventricular side. 
     The second frame portion can include a second anchoring feature. The second anchoring feature can include a second plurality of anchors. Anchors of the second plurality of anchors can be V-shaped. When the prosthesis transitions from an expanded configuration to a collapsed configuration, anchors of the second plurality of anchors can extend radially outwardly and upwardly. When the prosthesis transitions from an expanded configuration to a collapsed configuration, anchors of the second plurality of anchors can extend radially outwardly and downwardly. 
     The replacement heart valve can include a skirt extending around at least a portion of the prosthesis. At least a portion of the skirt can extend along an exterior of the second frame portion. At least a portion of the skirt can extend along an interior of the second frame portion. 
     The valve body can include one or more intermediate components. The one or more intermediate components can be positioned between the first frame body and the valve leaflets. 
     The first frame portion and the second frame portion can be separate components. The first frame portion can include a plurality of first eyelets. The second frame portion can include a plurality of second eyelets. Each of the plurality of first eyelets can correspond with each of the plurality of second eyelets. The first frame portion and the second frame portion can be coupled at each of the plurality of first and second eyelets. 
     The first frame portion and the second frame portion can form a monolithic component. 
     The first frame body can include one or more rows of cells. One or more portions of the first frame body can form a cylindrical shape, a bulbous shape, and/or a frustoconical shape. 
     In some embodiments, a replacement heart valve prosthesis can include a valve body including three flexible leaflets. The flexible leaflets can be made from pericardium. The prosthesis can include a self-expanding, metallic support structure surrounding and supporting the valve body. The support structure can be sized for deployment in a native mitral valve. 
     The support structure can include a valve frame having an upper portion, an intermediate portion, and a lower portion. The support structure can include a plurality of anchors which can be coupled to the lower portion of the valve frame. Each of the anchors can extend radially outwardly and/or upwardly. 
     The support structure can include a sealing frame. The sealing frame can be coupled to and disposed radially outwardly of the valve frame. The sealing frame can have an upper portion, an intermediate portion and a lower portion. A clearance can be provided between the sealing frame and the valve frame. The plurality of anchors can have ends disposed radially outwardly of the sealing frame. 
     The upper portion of the sealing frame can be coupled to the upper portion of the valve frame. The upper portion of the sealing frame can be sutured to the upper portion of the valve frame. The sealing frame can be more flexible than the valve frame for conforming to a mitral valve annulus. The support structure can be adapted to capture native mitral valve leaflets between the sealing frame and the anchors. 
     The intermediate portion of the sealing frame can have a diameter in the range of about 35 mm to 55 mm. At least a portion of the sealing frame can be covered by fabric. The lower portion of the sealing frame can have a larger diameter than the upper portion of the sealing frame. The intermediate portion of the sealing frame can have a larger diameter than the lower portion of the sealing frame. 
     The sealing frame can be convex. At least a portion of the sealing frame can be generally frustoconical. For example, the upper portion and/or lower portion of the sealing frame can be generally frustonical. At least a portion of the sealing frame can be generally cylindrical. For example, at least the intermediate portion of the sealing frame can be generally cylindrical. 
     The valve frame can be bulbous. The intermediate portion of the valve frame can have a diameter which is less than the diameter of the intermediate portion of the sealing frame. The diameter of the intermediate portion of the valve frame can be in the range of about 28 mm to about 32 mm. 
     The anchoring features can be axially and/or radially biased or compressible. Tips of the anchoring features can be formed from one or more wires. The wires can be looped to form a generally three-dimensional teardrop shape. The wires may be spiraled to form a generally three-dimensional conical shape. Tips of the anchoring features can have a serpentine shape. Tips of the anchoring features can be formed from one or more foreshortening cells. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages are described below with reference to the drawings, which are intended to illustrate embodiments of prostheses including embodiments of various components of these prostheses. 
         FIG.  1    is a side-oriented cross-sectional schematic view of an embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  2    is a top-oriented perspective view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  3    is a bottom-oriented perspective view of the prosthesis of  FIG.  2   . 
         FIG.  4    is a top view of the prosthesis of  FIG.  2     
         FIG.  5    is a bottom view of the prosthesis of  FIG.  2   . 
         FIG.  6    is a bottom-oriented perspective view of the inner frame and valve body of  FIG.  2   . 
         FIG.  7    is a side view of a front-half of another embodiment of an outer frame. 
         FIG.  8    is a top view of the outer frame of  FIG.  2   . 
         FIG.  9    is a side view of a front-half of another embodiment of an inner frame. 
         FIG.  10    is a top view of the inner frame of  FIG.  2   . 
         FIGS.  11 A- 11 K  are side-oriented schematic views of other embodiments of a prosthesis having an inner frame and an outer frame. 
         FIG.  12    is a side-oriented schematic view of an embodiment of a prosthesis having a frame body, a mesh anchoring feature, and a valve body. 
         FIG.  13    is a top view of the prosthesis of  FIG.  12   . 
         FIG.  14    is a bottom view of the prosthesis of  FIG.  12   . 
         FIG.  15    is a side-oriented cross-sectional schematic view of an embodiment of a prosthesis having a frame, a mesh anchoring feature, a valve body, and a skirt. 
         FIG.  16    is a top-oriented perspective view of an embodiment of a prosthesis having a frame, a mesh anchoring feature, a valve body, and a skirt in a partially assembled state. 
         FIG.  17    is an enlarged, side-oriented cross-sectional view of the prosthesis of  FIG.  16   . 
         FIG.  18    is a side view of the frame and mesh anchoring feature of  FIG.  16   . 
         FIG.  19    is a top-oriented perspective view of the frame of  FIG.  16   . 
         FIG.  20    is a side view of an embodiment of another embodiment of a prosthesis having a frame, a valve body, a braided seal, and a skirt in a partially assembled configuration. 
         FIG.  21    is a side view of an embodiment of the prosthesis of  FIG.  20    in an assembled configuration. 
         FIG.  22    is a top-oriented perspective view of another embodiment of the frame of  FIG.  21   . 
         FIG.  23    is a side view of an embodiment of a portion of a frame having a circumferentially curved anchoring feature. 
         FIG.  24    is a side-oriented schematic view of the portion of the frame of  FIG.  23    positioned between chordae tendineae of a heart. 
         FIG.  25    is a side view of another embodiment of a portion of a frame having a circumferentially curved anchoring feature. 
         FIG.  26    is a flat, cutting pattern for another embodiment of a frame having a circumferentially curved anchoring feature. 
         FIG.  27    is a side view of a portion of the frame of  FIG.  26    in an expanded configuration. 
         FIG.  28 A -30 illustrate schematic representations of the prosthesis of  FIG.  1    positioned within a heart, with  FIGS.  28 A-B  illustrating the prosthesis in situ with distal anchors contacting the ventricular side of a mitral valve annulus,  FIG.  29    illustrating the prosthesis in situ with distal anchors not contacting the ventricular side of the mitral valve annulus, and  FIG.  30    illustrating the prosthesis in situ with distal anchors not extending between the chordae tendineae. 
         FIG.  31    is a cross-sectional view of a distal end of an embodiment of a delivery system loaded with an embodiment of a prosthesis. 
         FIG.  32    is a cross-sectional view of a distal end of another embodiment of a delivery system loaded with another embodiment of a prosthesis. 
         FIG.  33    is a side-oriented cross-sectional schematic view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  34    is a top-oriented perspective view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  35    is a bottom view of the prosthesis of  FIG.  34   . 
         FIG.  36    is a top-oriented perspective view of another embodiment of an inner frame. 
         FIG.  37    is a top-oriented perspective view of another embodiment of an outer frame. 
         FIG.  38 A  is a side-oriented cross-sectional schematic view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  38 B  is a side-oriented cross-sectional schematic view of the prosthesis of  FIG.  38 A  in a native mitral valve. 
         FIG.  39    is a top-oriented perspective view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  40    is a top view of the prosthesis of  FIG.  39   . 
         FIG.  41    is a bottom-oriented perspective view of the prosthesis of  FIG.  39   . 
         FIG.  42    is a side view of a front-half of the inner frame of  FIG.  39   . 
         FIG.  43    is a top-oriented perspective view of another embodiment of an outer frame. 
         FIG.  44    is a top-oriented perspective view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  45    is a bottom-oriented perspective view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  46    is a side-oriented cross-sectional schematic view of another embodiment of a prosthesis having an inner frame, an outer frame, a valve body, and a skirt. 
         FIG.  47    is a side-oriented cross-sectional schematic view of the prosthesis of  FIG.  46    illustrating the commissure of a leaflet. 
         FIG.  48    is a side-oriented schematic view of an embodiment of an anchoring feature. 
         FIG.  49    is a side-oriented schematic view of another embodiment of an anchoring feature. 
         FIG.  50    is a side-oriented schematic view of an embodiment of an anchoring feature. 
         FIG.  51    is a side-oriented schematic view of another embodiment of an anchoring feature. 
         FIG.  52    is a side-oriented schematic view of an embodiment of an anchoring feature. 
         FIG.  53    is a side-oriented schematic view of another embodiment of an anchoring feature. 
         FIGS.  54 A- 57 H  illustrate schematic representations of delivery procedures utilizing embodiments of prostheses and delivery systems described herein. 
         FIGS.  58  and  59    illustrate schematic representations of embodiments of prostheses positioned within a heart. 
     
    
    
     DETAILED DESCRIPTION 
     The present specification and drawings provide aspects and features of the disclosure in the context of several embodiments of prostheses, replacement heart valves, and methods that are configured for use in the vasculature of a patient, such as for replacement of natural heart valves in a patient. These embodiments may be discussed in connection with replacing specific valves such as the patient’s mitral valve. However, it is to be understood that the features and concepts discussed herein can be applied to replacing other types of valves including, but not limited to, the aortic valve, the pulmonary valve, and the tricuspid valve. Moreover, it is to be understood that the features and concepts discussed herein can be applied to products other than heart valve implants. For example, the controlled positioning, deployment, and/or securing features described herein can be applied to medical implants, for example other types of expandable prostheses, for use elsewhere in the body, such as within a vein, or the like. In addition, particular features of a prosthesis should not be taken as limiting, and features of any one embodiment discussed herein can be combined with features of other embodiments as desired and when appropriate. 
     Certain terminology may be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as “upper”, “lower”, “upward”, “downward”, “above”, “below”, “top”, “bottom” and similar terms refer to directions in the drawings to which reference is made. Terms such as “proximal”, “distal”, “radially outward”, “radially inward”, “outer”, “inner”, and “side”, describe the orientation and/or location of portions of the components or elements within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the components or elements under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second”, and other such numerical terms referring to structures neither imply a sequence or order unless clearly indicated by the context. 
     In some embodiments, the term “proximal” may refer to the parts of the prostheses, or components thereof, which are located closer to the operator of the device and system (e.g., the clinician implanting the prosthesis). The term “distal” may refer to the parts of the prostheses, or components thereof, which are located further from the operator of the device and system (e.g., the clinician implanting the prosthesis). However, it is to be understood that this terminology may be reversed depending on the delivery technique utilized (e.g., a transapical approach as compared to a transseptal approach). In some situations, the prosthesis, or components thereof, may be oriented such that an upper end is a proximal portion and a lower end is a distal portion. 
     In some situations, the prosthesis, or components thereof, the upper end may be an inflow end and the lower end may be an outflow end. For example, a valve body used with the prosthesis can allow flow from the upper end to the lower end. However, it is to be understood that the inflow end and the outflow end may be reversed. For example, the valve body used with the prosthesis can allow flow from the lower end to the upper end. 
     A longitudinal axis of the prosthesis, or components thereof, may be defined as the central axis that extends through the center of the prosthesis or component between the upper and lower ends of the prosthesis or component (e.g., the prosthesis, the outer frame, and/or the inner frame). The prostheses described herein may be replacement valves that can be designed to replace a damaged or diseased native heart valve such as a mitral valve, as discussed above. It should be understood that the prostheses are not limited to being a replacement valve. 
     As will be described in further detail below, the prostheses can include an inner frame and/or an outer frame. In some embodiments, the inner frame can be a valve frame designed to support a valve body. In some embodiments, the outer frame can be a sealing frame designed to form a seal about a periphery of the outer frame. For example, the outer frame can engage tissue of a body cavity about a periphery of the outer frame and form a seal with said tissue. In some embodiments described herein, the outer frame can be attached to the inner frame at one or more stationary couplings such that the outer frame is fixed to the inner frame at one or more locations. It is to be understood that the outer frame can be attached to the inner frame via one or more movable couplings such as, but not limited to, rails. This can beneficially allow the outer frame to be adjusted relative to the inner frame to better conform to the anatomy of a patient’s body cavity. 
     The inner frame and/or outer frame may be described as having an upper region, an intermediate region, and a lower region. In some situations, such as those in which the prostheses are positioned within a native mitral valve, the upper region can be generally positioned supra-annularly (i.e., above the plane of the annulus), the intermediate region can be generally positioned intra-annularly (i.e., within the plane of the annulus), and the lower region can be positioned sub-annularly (i.e., below the plane of the annulus). However, it is to be understood that in some situations, the positioning of the inner frame and/or outer frame relative to the annulus can differ. Moreover, it is to be understood that in some embodiments, the inner frame and/or outer frame can omit one or more of the upper region, the intermediate region, and/or the lower region. 
     While certain combinations of inner frames and outer frames are described herein, it is to be understood that the inner frames and outer frames can be interchanged. This can beneficially allow the prosthesis to be configured in a manner which better suits the native anatomy of the patient. Moreover, while the inner frames and outer frames can be attached prior to delivery into the patient, it is to be understood that the inner frames and outer frames can be delivered separately into the patient and subsequently attached in the patient’s body. This can beneficially reduce the crimp profile when delivering the frames to the body cavity. The prostheses described herein can be used as a standalone device. For example, the prosthesis can be deployed at a native mitral valve and be sized and shaped appropriately to replace the function of the native mitral valve. However, it is to be understood that the prostheses described herein can be used with other devices. For example, one or more clips can be used to hold together native leaflets of a heart valve. This can advantageously allow a smaller prosthesis to be utilized at the native mitral valve. 
     Embodiments of Replacement Valves and Frames 
     With reference to  FIG.  1   , an embodiment of a prosthesis  100  in an expanded configuration is illustrated. The prosthesis  100  can include an inner frame  120 , an outer frame  140 , a valve body  160 , and a skirt  180 . A longitudinal axis  102  of the prosthesis  100  may be defined as the central axis that extends through the center of the prosthesis  100  between the upper and lower ends of the prosthesis  100 . In some situations, the prosthesis  100  may be oriented such that an upper end of the prosthesis  100  is a proximal portion and a lower end of the prosthesis  100  is a distal portion. The illustrated prosthesis  100 , as well as other prostheses described herein, may include components which are self-expanding or balloon expandable. For example, in some embodiments, the inner frame  120  and/or outer frame  140  can be self-expanding. The prosthesis  100 , as well as other prostheses described herein, may be a replacement valve that can be designed to replace a damaged or diseased native heart valve such as a mitral valve, as discussed above. It should be understood that the prosthesis  100 , as well as other prostheses described herein, are not limited to being a replacement valve. 
     With reference first to the inner frame  120  illustrated in  FIG.  1   , the inner frame  120  can provide a structure to which various components of the prosthesis  100  can be attached. The inner frame  120  can include an inner frame body  122  and an inner frame anchoring feature  124 . The inner frame body  122  can have an upper region  126 , an intermediate region  128 , and a lower region  130 . As shown, the inner frame body  122  can have a generally cylindrical shape such that the diameters of the upper region  126 , the intermediate region  128 , and the lower region  130  are generally equivalent. However, it is to be understood that the diameters of the upper region  126 , the intermediate region  128 , and/or the lower region  130  can be different. For example, in some embodiments, a diameter of the intermediate region  128  can be larger than the upper region  126  and the lower region  130  such that the frame body  122  has a generally bulbous shape. In some embodiments, the diameter of the lower region  130  can be larger than the diameter of the upper region  126 . In other embodiments, the diameter of the upper region  126  can be larger than the diameter of the lower region  130 . Moreover, although the inner frame body  122  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  122  can have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     In some situations, such as those in which the prosthesis  100  is positioned within a native mitral valve, the upper region  126  can be generally positioned supra-annularly (i.e., above the plane of the annulus), the intermediate region  128  can be generally positioned intra-annularly (i.e., within the plane of the annulus), and the lower region  130  can be positioned sub-annularly (i.e., below the plane of the annulus). However, it is to be understood that in some situations, the positioning of the inner frame  120  relative to the annulus can differ. Moreover, it is to be understood that in some embodiments, the inner frame  120  can omit one or more of the upper region  126 , the intermediate region  128 , and/or the lower region  130 . 
     As shown in the illustrated embodiment, the inner frame anchoring feature  124  can extend generally downwardly and/or radially outwardly at or proximate a lower end of the lower region  130  of the inner frame body  122 . The inner frame anchoring feature  124  can extend upwardly towards an end of the inner frame anchoring feature  124 . As will be discussed in further detail below, components of the inner frame  120 , such as the inner frame anchoring feature  124 , can be used to attach or secure the prosthesis  100  to a native valve. For example, in some situations, the inner frame anchoring feature  124  can be used to attach or secure the prosthesis  100  to a native mitral valve. In such an embodiment, the inner frame anchoring feature  124  can be positioned to contact or engage a native mitral valve annulus on a ventricular side, tissue beyond the native valve annulus on a ventricular side, native leaflets on a ventricular side, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. When positioned within the native mitral valve, the inner frame anchoring feature  124  can beneficially eliminate, inhibit, or limit upward movement of the prosthesis  100  when subject to upwardly directed forces such as those which are applied on the prosthesis  100  during systole. 
     The inner frame  120  can be formed from many different materials including, but not limited to a shape-memory metal such as Nitinol. The inner frame  120  can be formed from a plurality of struts forming open cells. In some embodiments, the inner frame  120  can have a relatively rigid construction as compared to other components of the prosthesis  100  including, but not limited to, the outer frame  140 . This can be achieved, for example, by the dimensions of the struts and by the configuration of the struts. The relatively rigid construction can more strongly resist deformation when subject to stress. This can be beneficial during certain portions of the cardiac cycle, such as systole, during which the inner frame  120  may be subject to significant stresses on the inner frame anchoring feature  124 . The relatively rigid construction can also be beneficial when a valve body  160  is positioned within the inner frame  120  to maintain the shape of the valve body  160 . Moreover, the relatively rigid construction can be beneficial when the inner frame  120  is used for a valve-in-valve procedure wherein a supplemental prosthesis is positioned within the inner frame  120 . However, although the inner frame  120  has been described as having a relatively rigid construction, it is to be understood that in some embodiments the inner frame  120   can have a construction relatively flexible construction. For example, the inner frame  120  can have a constructions which is about as flexible as, or more flexible than, other components of the prosthesis  100 , such as the outer frame  140 . 
     The inner frame  120  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other frames described herein such as, but not limited to, frames  220 ,  400 ,  520   a - k ,  620 , 720, 820, 920,  1000 ,  1100 ,  1202 ,  1520 ,  1620 ,  1700 ,  1920 ,  2020 ,  2220 ,  2320 ,  2420 ,  2910 ,  3010 ,  3110 ,  3210  discussed below. The inner frame  120 , and any other frame described herein, may include features and concepts similar to those disclosed in U.S. Pat. Nos. 8,403,983, 8,414,644, and 8,652,203, U.S. Publication Nos. 2011/0313515, 2014/0277390, 2014/0277427, 2014/0277422, and 2015/0328000, and U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entireties of each of which are hereby incorporated by reference and made a part of this specification. This is inclusive of the entire disclosure and is not in any way limited to the disclosure of the associated frames. Moreover, although the inner frame  120  has been described as including an inner frame body  122  and an inner frame anchoring feature  124 , it is to be understood that the inner frame  120  need not include all components. For example, in some embodiments, the inner frame  120  can include the inner frame body  122  while omitting the inner frame anchoring feature  124 . Moreover, although the inner frame body  122  and the inner frame anchoring feature  124  have been illustrated as being unitarily or monolithically formed, it is to be understood that in some embodiments the inner frame body  122  and the inner frame anchoring feature  124  can be formed separately. In such embodiments, the separate components can be attached using any of the fasteners and/or techniques described herein. For example, the inner frame anchoring feature  124  can be formed separately from the inner frame body  122  and can be attached to the inner frame body  122 . 
     With reference next to the outer frame  140  illustrated in  FIG.  1   , the outer frame  140  can provide a structure to which various components of the prosthesis  100  can be attached. The outer frame  140  can be attached to the inner frame  120  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the inner frame  120  and the outer frame  140 ), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. The inner frame  120  and the outer frame  140  can be indirectly attached via an intermediate component, such as the skirt  180 . 
     The outer frame  140  can be attached to the inner frame  120  at one or more attachment points. As will be described in further detail, the outer frame  140  can be tautly attached to the inner frame  120  such that little to no relative movement between the outer frame  140  and the inner frame  120  occurs at the one or more attachment points. In other embodiments, the outer frame  140  can be loosely attached to the inner frame  120  such that some relative movement between the outer frame  140  and the inner frame  120  can occur at the one or more attachment points. Although the outer frame  140  is illustrated as a separate component from the inner frame  120 , it is to be understood that the frames  120 ,  140  can be unitarily or monolithically formed. 
     As shown in the illustrated embodiment, the outer frame  140  can include an outer frame body  142  and an outer frame anchoring feature  144 . The outer frame body  142  can have an upper region  146 , an intermediate region  148 , and a lower region  150 . In some situations, such as those in which the prosthesis  100  is positioned within a native mitral valve, the upper region  146  can be generally positioned supra-annularly, the intermediate region  148  can be generally positioned intra-annularly, and the lower region  150  can be positioned sub-annularly. However, it is to be understood that in some situations, the positioning of the outer frame  140  relative to the annulus can differ. Moreover, it is to be understood that in some embodiments, the outer frame  140  can omit one or more of the upper region  146 , the intermediate region  148 , and/or the lower region  150 . 
     When in an expanded configuration such as a fully expanded configuration, the outer frame body  142  can have an enlarged shape with the intermediate region  148  and the lower region  150  being larger than the upper region  146 . The enlarged shape of the outer frame body  142  can advantageously allow the outer frame body  142  to engage a native valve annulus, native valve leaflets, or other tissue of the body cavity, while spacing the upper end from the heart or vessel wall. This can help reduce undesired contact between the prosthesis  100  and the heart or vessel, such as the atrial and ventricular walls of the heart. 
     The upper region  146  of the outer frame body  122  can include a generally longitudinally-extending section  146   a  and an outwardly-extending section  146   b . The longitudinally-extending section  146   a  can be generally concentric with the inner frame body  122 . The outwardly-extending section  146   b  can extend radially outwardly away from the longitudinal axis  102  of the prosthesis  100 . The outwardly-extending section  146   b  can extend in a direction that is more perpendicular to the longitudinal axis  102  than parallel and/or in a downward direction from the longitudinally-extending section  146   a . However, it is to be understood that the outwardly-extending section  146   b  can extend generally perpendicularly to the longitudinal axis  102  and/or in an upward direction from the longitudinally-extending section  146   a . Moreover, it is to be understood that the longitudinally-extending section  146   a  can be omitted such that the upper region  146  extends radially outwardly at the upper end of the upper region  146 . 
     The intermediate region  148  of the outer frame body  142  can extend generally downwardly from the outwardly-extending section  146   b  of the upper region  146 . As shown, the intermediate region  148  can have a generally constant diameter from an upper end of the intermediate region  148  to a lower end of the intermediate region  148  such that the intermediate region  148  forms a generally cylindrical shape. However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. For example, a diameter of the portion between the upper end and the lower end can be larger than the upper end and the lower end such that the intermediate region  148  has a generally bulbous shape. In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. 
     The lower region  150  of the outer frame body  142  can extend generally downwardly from the lower end of the intermediate region  148 . As shown, the lower region  150  of the outer frame body  142  can have a generally constant diameter from an upper end of the lower region  150  to a lower end of the lower region  150  such that the lower region  150  forms a generally cylindrical shape. However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. For example, in some embodiments, the diameter of the upper end of the lower region  150  can be greater than the diameter of the lower end of the lower region  150  such that the lower region  150  extends radially inwardly towards the longitudinal axis  102  of the prosthesis  100 . In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. 
     As shown, the diameters of the intermediate region  148  and the lower region  150  are generally equivalent such that the intermediate region  148  and the lower region  150  together form a generally cylindrical shape. However, it is to be understood that the diameters of the intermediate region  148  and the lower region  150  can be different. For example, the diameter of the lower region  150  can be less than the diameter of the intermediate region  148 . Moreover, although the outer frame body  142  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  142  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  140  illustrated in  FIG.  1   , the outer frame anchoring feature  144  can extend outwardly relative to the longitudinal axis  102  of the prosthesis  100 . The outer frame anchoring feature  144  can extend at or proximate the juncture between the upper region  146  and the intermediate region  148  of the outer frame body  142 . The outer frame anchoring feature  144  can extend in a direction that is more perpendicular to the longitudinal axis  102  than parallel and/or can extend in a downward direction from the longitudinally-extending section  146   a . As shown, the outer frame anchoring feature  144  can extend in a direction generally aligned with the outwardly-extending section  146   b  of the upper region  146 . However, it is to be understood that the outer frame anchoring feature  144  can extend generally perpendicularly to the longitudinal axis  102  and/or in an upward direction. 
     As will be discussed in further detail below, components of the outer frame  140 , such as the outer frame body  142  can be used to attach or secure the prosthesis  100  to a native valve, such as a native mitral valve. For example, the intermediate region  148  of the outer frame body  142  and/or the outer anchoring feature  144  can be positioned to contact or engage a native valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. In situations where the outer frame body  142  is positioned within a native mitral valve, the outer frame body  142  can beneficially eliminate, inhibit, or limit downwardly directed forces such as those which are applied on the prosthesis  100  during diastole and/or upwardly directed forces such as those which are applied on the prosthesis  100  during systole. As another example, the outer frame body  142  can be sized and positioned relative to the inner frame anchoring feature  124  such that tissue of the body cavity positioned between the outer frame body  142  and the inner frame anchoring feature  124 , such as native valve leaflets and/or a native valve annulus, can be engaged or pinched to further secure the prosthesis  100  to the tissue. For example, the lower region  150  of the outer frame body  142  can be positioned at or proximate a tip or end of the inner frame anchoring feature  124 . As shown, the lower region  150  of the outer frame body  142  is positioned such that at least a portion is positioned radially inward of and below the inner frame anchoring feature  124 . In some embodiments, a portion of the outer frame  140 , such as the lower region  150 , can be attached to the inner frame body  122  via one or more tethers or sutures (as shown in  FIG.  45   ) to limit the outward extension of the outer frame  140  relative to the inner frame body  122 . This can beneficially maintain a portion of the outer frame  140  between the inner frame body  122  and the inner frame anchoring feature  124 . Although the inner frame anchoring feature  124  is shown extending from the inner frame body  122 , it is to be understood that such an anchoring feature can extend from the outer frame body  140 . 
     Use of an inner frame  120  and an outer frame  140  can be beneficial for the design of the prosthesis in that the inner frame  120  can be designed to suit the structure of the valve body  160  and the outer frame  140  can be designed to suit the anatomy of the body cavity in which the prosthesis  100  is to be used. For example, the valve body  160  can be cylindrical and have a smaller diameter than the body cavity. In such an embodiment, the inner frame  120  can advantageously have a smaller shape and/or size to support the valve body  160  while the outer frame  140  can have a larger shape and/or size to secure the prosthesis  100  to the body cavity. Moreover, in embodiments in which the outer frame  140  is larger than the inner frame  120 , the shape of the outer frame  140  can beneficially enhance hemodynamic performance. For example, the shape of the outer frame  140  with a larger, generally cylindrical intermediate region  148  can allow for significant washout on an underside of the valve body  160 . This washout can beneficially reduce the risk of thrombosis or clot formation under and around the valve body  160 . 
     The outer frame  140  can be formed from many different materials including, but not limited to, a shape-memory metal such as Nitinol. The outer frame  140  can be formed from a plurality of struts forming open cells. In some embodiments, the outer frame  140  can have a more flexible construction as compared to other components of the prosthesis  100  such as, but not limited to, the inner frame  120 . This can be achieved, for example, by the dimensions of the struts and by the configuration of the struts. For example, fewer struts, thinner struts, and/or a different material for the struts can be used. The more flexible construction can allow the outer frame  140  to better conform to the anatomy of the body cavity, such a native valve annulus and/or native leaflets. This can be beneficial for anchoring against the body cavity and/or forming a seal against the body cavity. However, it is to be understood that in some embodiments the outer frame  140  can have a construction which is about as rigid as, or more rigid than, other components of the prosthesis  100 , such as the inner frame  120 . 
     The outer frame  140  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other frames described herein such as, but not limited to, frames  240 ,  300 ,  540   a - k ,  560   h ,  1204 ,  1540 ,  1640 ,  1800 ,  1940 ,  2040 ,  2100 ,  2240 ,  2340 ,  2440 ,  2920 ,  3020 ,  3120 ,  3220  discussed below. The outer frame  140 , and any other frame described herein, may include features and concepts similar to those disclosed in U.S. Pat. Nos. 8,403,983, 8,414,644, and 8,652,203, U.S. Publication Nos. 2011/0313515, 2014/0277390, 2014/0277427, 2014/0277422, and 2015/0328000, and U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entireties of each of which have been incorporated by reference. Moreover, although the outer frame  140  has been described as including an outer frame body  142  and an outer frame anchoring feature  144 , it is to be understood that the outer frame  140  need not include all components. For example, in some embodiments, the outer frame  140  can include the outer frame body  142  while omitting the outer frame anchoring feature  144 . Moreover, although the outer frame body  142  and the outer frame anchoring feature  144  have been illustrated as being unitarily or monolithically formed, it is to be understood that in some embodiments the outer frame body  142  and the outer frame anchoring feature  144  can be formed separately. In such embodiments, the separate components can be attached using any of the fasteners and techniques described herein. For example, the outer frame anchoring feature  144  can be formed separately from the outer frame body  142  and can be attached to the outer frame body  142 . 
     With reference next to the valve body  160  illustrated in  FIG.  1   , the valve body  160  can be attached to the inner frame  120  within an interior of the inner frame  120 . The valve body  160  can function as a one-way valve to allow blood flow in a first direction through the valve body  160  and inhibit blood flow in a second direction through the valve body  160 . For example, in situations where the upper end of the prosthesis  100  is a proximal end and the lower end of the prosthesis  100  is a distal end, the valve body  160  can allow blood flow in a proximal-to-distal direction and inhibit blood flow in a distal-to-proximal direction. The valve body  160  can include a plurality of valve leaflets  162 , for example three leaflets  162 , which are joined at commissures. The leaflets  162  can be formed from biocompatible materials including, but not limited to, pericardium and/or synthetic materials. 
     The valve body  160  can include a liner  164 . The liner  164  can be used to assist with fluid flow through and/or around the prosthesis  100 , such as through and around the inner frame  120  and the valve leaflets  162 . The liner  164  can surround at least a portion of the valve leaflets  162  and be connected to one or more of the valve leaflets  162 . For example, as shown in the illustrated embodiment, the one or more valve leaflets  162  can be attached to the liner  164  along an arcuate or fixed edge of the valve leaflets  162 . The liner  164  can extend from the arcuate or fixed edge of the leaflet  162  and extend upwardly towards an upper end of the inner frame  120 . 
     The valve body  160  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other valve bodies described herein such as, but not limited to, valve bodies  260 , 660, 760, 870, 970,  1560 ,  1660 ,  1960 ,  2060 ,  2260 ,  2360 ,  2460 , discussed below. Moreover, although the valve body  160  has been described as including a plurality of leaflets  162  and a liner  164 , it is to be understood that the valve body  160  need not include all features. For example, in some embodiments, the valve body  160  can include the plurality of valve leaflets  162  while omitting the liner  164 . It is to be understood that other types of valves can be utilized in conjunction with, or in lieu of, the valve body  160 . For example, the valve can be a mechanical valve such as a ball and cage. 
     With continued next to the skirt  180  illustrated in  FIG.  1   , the skirt  180  can be attached to the inner frame  120  and/or outer frame  140 . As shown, the skirt  180  can be positioned around and secured to a portion of, or the entirety of, the exterior of the inner frame  120  and/or outer frame  140 . The skirt  180  can also be secured to a portion of the valve body  160 . The skirt  180  can follow the contours of the outer frame  140 , such as the contours of the upper region  146 , the intermediate region  148 , and/or the lower region  150 . In some embodiments, the skirt  180  can be used to attach the outer frame  140  to the inner frame  120 . Although not shown, it is to be understood that the skirt  180  can be positioned around and secured to a portion of, or the entirety of, an interior of the inner frame  120  and/or the outer frame  140 . Moreover, it is to be understood that while the skirt  180  can follow the contours of portions of the inner frame  120  and the outer frame  140 , at least a portion of the skirt  180  can be spaced apart from at least a portion of both the inner frame  120  and the outer frame  140 . In some embodiments, the skirt  180  can be spaced apart from the upper region  146  of the outer frame  140 . For example, the skirt  180  can be positioned below the upper region  146 . In such an embodiment, the spaced-apart portion of the skirt  180  can be loose such that the skirt  180  is movable relative to the upper region  146  or can be taut such that the skirt  180  is generally fixed in position. 
     The skirt  180  can be annular and can extend entirely circumferentially around the inner frame  120  and/or outer frame  140 . The skirt  180  can prevent or inhibit backflow of fluids, such as blood, around the prosthesis  100 . For example, with the skirt  180  positioned annularly around an exterior of the inner frame  120  and/or outer frame  140 , the skirt  180  can create an axial barrier to fluid flow exterior to the inner frame  120  and/or outer frame  140  when deployed within a body cavity such as a native valve annulus. The skirt  180  can encourage tissue in-growth between the skirt  180  and the natural tissue of the body cavity. This may further help to prevent leakage of blood flow around the prosthesis  100  and can provide further securement of the prosthesis  100  to the body cavity. In some embodiments, the skirt  180  can be tautly attached to the inner frame  120  and/or outer frame  140  such that the skirt  180  is generally not movable relative to the inner frame  120  and/or outer frame  140 . In some embodiments, the skirt  180  can be loosely attached to the inner frame  120  and/or outer frame  140  such that the skirt  180  is movable relative to the inner frame  120  and/or outer frame  140 . 
     The skirt  180  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other skirts described herein such as, but not limited to, skirts  280 , 780, 890, 990,  1580 ,  1590 ,  1680 ,  1690 ,  1980 ,  1990 ,  2080 ,  2280 ,  2380 ,  2480 ,  2490 , discussed below. 
     Although the prosthesis  100  has been described as including an inner frame  120 , an outer frame  140 , a valve body  160 , and a skirt  180 , it is to be understood that the prosthesis  100  need not include all components. For example, in some embodiments, the prosthesis  100  can include the inner frame  120 , the outer frame  140 , and the valve body  160  while omitting the skirt  180 . Moreover, although the components of the prosthesis  100  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  100  can be integrally or monolithically formed. For example, in some embodiments, the inner frame  120  and the outer frame  140  can be integrally or monolithically formed as a single component. 
     With reference next to  FIGS.  2 - 6   , an embodiment of a prosthesis  200  in an expanded configuration, or components of the prosthesis  200 , are illustrated. The prosthesis  200  can include an inner frame  220 , an outer frame  240 , a valve body  260 , and a skirt  280 . A longitudinal axis of the prosthesis  200  may be defined as the central axis that extends through the center of the prosthesis  200  between the upper and lower ends of the prosthesis  200 . In some situations, the prosthesis  200  may be oriented such that an upper end of the prosthesis  200  is a proximal portion and a lower end of the prosthesis  200  is a distal portion. 
     With reference first to the outer frame  240  illustrated in  FIGS.  2 - 5   , the outer frame  240  can include an outer frame body  242  and an outer frame anchoring feature  244 . The outer frame  240  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of outer frame  140  described above in connection with  FIG.  1   . 
     The outer frame body  242  can have an upper region  246 , an intermediate region  248 , and a lower region  250 . As shown, when in an expanded configuration such as the fully expanded configuration, the outer frame body  242  can have an enlarged shape with an intermediate region  248  and a lower region  250  being larger than the upper region  246 . The enlarged shape of the outer frame body  242  can advantageously allow the outer frame body  242  to engage a native valve annulus, native valve leaflets, or other body cavity, while spacing the inlet and outlet from the heart or vessel wall. This can help reduce undesired contact between the prosthesis  200  and the heart or vessel, such as the atrial and ventricular walls of the heart. 
     The upper region  246  of the outer frame body  242  can include a generally longitudinally-extending section  246   a  and an outwardly-extending section  246   b . The longitudinally-extending section  246   a  can be generally concentric with the inner frame  220 . The outwardly-extending section  246   b  can extend radially outwardly away from the longitudinal axis of the prosthesis  200 . In some embodiments, the outwardly-extending section  246   b  can extend in a direction that is more perpendicular to the longitudinal axis  202  than parallel and/or can extend in a downward direction from the longitudinally-extending section  246   a . However, it is to be understood that the outwardly-extending section  246   b  can extend generally perpendicularly to the longitudinal axis and/or in an upward direction from the longitudinally-extending section  246   a . Moreover, it is to be understood that the longitudinally-extending section  246   a  can be omitted. 
     In some embodiments, the outwardly-extending section  246   b  can form an angle of between about 20 degrees to about 70 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of between about 30 degrees to about 60 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of between about 40 degrees to about 50 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of about 45 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , any subrange within these ranges, or any other angle as desired. In some embodiments, the outwardly-extending section  246   b  can form an angle of less than 70 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of less than 55 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of less than 40 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , an angle of less than 25 degrees with a plane orthogonal to the longitudinal axis of the prosthesis  200 , or less than any other angle as desired 
     The intermediate region  248  of the outer frame body  242  can extend generally downwardly from the outwardly-extending section  246   b  of the upper region  246 . As shown, the intermediate region  248  can have a generally constant diameter from an upper end of the intermediate region  248  to a lower end of the intermediate region  248  such that the intermediate region  248  forms a generally cylindrical shape. However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. For example, in some embodiments, a diameter of the portion between the upper and lower ends can be larger than diameters of the upper and lower ends such that the intermediate region  248  has a generally bulbous shape (as shown, for example, in connection with frame  300  illustrated in  FIGS.  7 - 8   ). In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. 
     The general uniformity of the diameter of the intermediate region  248  from the upper end to the lower end, in conjunction with the axial dimension between the upper end and the lower end (i.e., the “height” of the intermediate region  248 ), provides for a significantly large circumferential area upon which a native valve annulus, or other body cavity, can be engaged. This can beneficially improve securement of the outer frame  240  to the native valve annulus or other body cavity. This can also improve sealing between the outer frame  240  and the native valve annulus, or other body cavity, thereby reducing paravalvular leakage. 
     At the juncture between the upper region  246  and the intermediate region  248 , the outer frame body  242  can include a bend  252 . The bend  252  can be a bend about a circumferential axis such that the intermediate region  248  extends in a direction more parallel to the longitudinal axis of the prosthesis  200  than the outwardly-extending section  246   b  of the upper region  246 . In some embodiments, the bend  252  can generally form an arc with an angle between about 20 degrees to about 90 degrees. For example, as shown in the illustrated embodiment, the arc can have an angle of about 45 degrees. In some embodiments, the bend  252  can form an arc with an angle between about 30 degrees to about 60 degrees. The radius of curvature of the arc may be constant such that the bend  252  forms a circular arc or may differ along the length of the bend  252 . 
     The lower region  250  of the outer frame body  242  can extend generally downwardly from the lower end of the intermediate region  248 . As shown, the lower region  250  of the outer frame body  242  can have a generally constant diameter from an upper end of the lower region  250  to a lower end of the lower region  250  such that the lower region  250  forms a generally cylindrical shape. However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. For example, in some embodiments, the diameter of the upper end of the lower region  250  can be greater than the diameter of the lower end of the lower region  250  such that the lower region  250  extends radially inwardly towards the longitudinal axis of the prosthesis  200 . In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. 
     As shown, the diameters of the intermediate region  248  and the lower region  250  are generally equivalent such that the intermediate region  248  and the lower region  250  together form a generally cylindrical shape. However, it is to be understood that the diameters of the intermediate region  248  and the lower region  250  can be different. For example, the diameter of the lower region  250  can be less than the diameter of the intermediate region  248 . Moreover, although the outer frame body  242  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  242  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     The outer frame body  242  in an expanded configuration can have a diameter at its widest portion of between about 30 mm to about 60 mm, between about 35 mm to about 55 mm, about 40 mm, any sub-range within these ranges, or any other diameter as desired. The outer frame body  242  in an expanded configuration can have a diameter at its narrowest portion between about 20 mm to about 40 mm, any sub-range within these ranges, or any other diameter as desired. In some embodiments, in an expanded configuration, the ratio of the diameter of the outer frame body  242  at its widest portion to the diameter of the frame body  242  at its narrowest portion can be about 3:1, about 5:2, about 2: 1, about 3:2, about 4:3, any ratio within these ratios, or any other ratio as desired. 
     The outer frame body  242  can have an axially compact configuration relative to the radial dimension. The outer frame body  242  in an expanded configuration can have an the axial dimension between the upper and lower ends of the outer frame body  242  (i.e., the “height” of the outer frame body  242 ) of between about 10 mm to about 40 mm, between about 18 mm to about 30 mm, about 20 mm, any sub-range within these ranges, or any other height as desired. In some embodiments, the ratio of the diameter of the largest portion of the outer frame body  242  to the height of the outer frame body  242  when the frame is in its expanded configuration can be about 3:1, about 5:2, about 2:1, about 3:2, about 4:3, about 13:10, about 5:4, or about 1:1. Thus, in some embodiments the width at the largest portion of the outer frame body  242  can be greater than the height of the outer frame body  242 . 
     With continued reference to the outer frame  240  illustrated in  FIGS.  2 - 5   , the outer frame body  242  can include a plurality of struts with at least some of the struts forming cells  254   a - c . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. For reference, the struts in  FIG.  2    have been highlighted to show the general configuration of these struts; however, it is to be understood that one or more of the struts may not actually be seen. For example, the skirt  280  can be formed from a non-transparent material and be positioned over the exterior of the outer frame body  242 . 
     The upper row of cells  254   a  can have an irregular octagonal shape such as a “heart” shape. The cell  254   a  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper portion of cells  254   a  can be formed from a set of circumferentially-expansible struts  256   a  having a zig-zag or undulating shape forming a repeating “V” shape. The circumferentially-expansible struts  256   a  can be inclined or curved radially outwardly away from the longitudinal axis of the prosthesis  200  such that an upper portion of the struts  256   a  are positioned closer to the longitudinal axis of the prosthesis  200  than the lower portion of the struts  256   a . The middle portion of cells  254   a  can be formed from a set of struts  256   b  extending downwardly from bottom ends of each of the “V” shapes. The struts  256   b  can extend along with a plane parallel to and/or extending through the longitudinal axis of the prosthesis  200 . The portion of the cells  254   a  extending upwardly from the bottom end of struts  256   b  may be considered to be a substantially non-foreshortening portion of the outer frame  240 . As will be discussed in further detail below, foreshortening refers to the ability of the frame to longitudinally shorten as the frame radially expands. 
     The lower portion of cells  254   a  can be formed from a set of circumferentially-expansible struts  256   c  having a zig-zag or undulating shape forming a repeating “V” shape. The lower tips or ends of the circumferentially-expansible struts  256   c  can be at or proximate the junction of the upper region  246  and the intermediate region  248 . In some embodiments, one or more of the upper ends or tips of the circumferentially-expansible struts  256   c  can be a “free” apex which is not connected to a strut. As shown in the illustrated embodiment, every other upper end or tip of circumferentially-expansible struts  256   c  is a free apex. However, it is to be understood that other configurations can be used. For example, every upper apex along the upper end can be connected to a strut. 
     As shown in the illustrated embodiment, the middle and/or lower rows of cells  254   b - c  can have a different shape from the cells  254   a  of the first row. The middle row of cells  254   b  can have a diamond or generally diamond shape. The cells  254   b - c  may be considered to be a substantially foreshortening portion of the outer frame  240 . The diamond or generally diamond shape can be formed via a combination of struts. The upper portion of cells  254   b  can be formed from the set of circumferentially-expansible struts  256   c  such that cells  254   b  share struts with cells  254   a . The lower portion of cells  254   b  can be formed from a set of circumferentially-expansible struts  256   d . As shown in the illustrated embodiment, one or more of the circumferentially-expansible struts  256   d  can extend generally in a downward direction. The one or more circumferentially-expansible struts  256   d  can incorporate the bend  252  such that an upper portion of the struts  256   d  can be positioned closer to the longitudinal axis of the prosthesis  200  than the lower portion of the struts  256   d  are to the longitudinal axis of the prosthesis  200 . In some embodiments, one or more of the circumferentially-expansible struts  256   d  can extend radially outwardly away from the longitudinal axis of the prosthesis  200 . As will be discussed in further detail below, these radially outward portions of struts  256   d  can form part of the outer frame anchoring feature  244 . 
     The lower row of cells  254   c  can have an irregular octagonal shape. The upper portion of cells  254   c  can be formed from the set of circumferentially-expansible struts  256   d  such that cells  254   c  share struts with cells  254   b . The lower portion of cells  254   c  can be formed from a set of circumferentially-expansible struts  256   e . Circumferentially-expansible struts  256   e  can extend generally in a downward direction. In some embodiments, the circumferentially-expansible struts  256   e  can extend radially inwardly towards the longitudinal axis of the prosthesis  200  (as shown, for example, in connection with frame  300  illustrated in  FIGS.  7 - 8   ). The circumferentially-expansible struts  256   e  can be inclined or curved towards the longitudinal axis of the prosthesis  200 . 
     While the struts  256   a - e  are generally described and illustrated as being straight segments, it is to be understood that some or all of the struts  256   a - e  may not form entirely straight segments. For example, the struts  256   a - e  can include some curvature such that the upper and/or lower apices are curved. 
     As shown in the illustrated embodiment, there can be a row of twelve cells  254   a , a row of twenty-four cells  254   b , and a row of twelve cells  254   c . While each of the cells  254   a - c  are shown as having the same shape as other cells  254   a - c  of the same row, it is to be understood that the shapes of cells  254   a - c  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. In some embodiments, the number of cells can correspond to the number of anchors or anchor tips forming the outer frame anchoring feature  244 . As shown, the number of cells in the upper row of cells  254   a  and the lower row of cells  254   c  can have a 1:1 correspondence with the number of anchors in the outer frame anchoring feature  244  (i.e., twelve cells in each row of cells  254   a ,  254   c  and twelve anchors for the anchoring features  244 ). The number of cells in the middle row of cells  254   b  can have a 2:1 correspondence with the number of anchors in the outer frame anchoring feature  244  (i.e., twenty-four cells in cells  254   b  and twelve anchors for the anchoring features  244 ). It is to be understood that other ratios of numbers of cells per row to number of anchors per anchoring feature can be used such as, but not limited to, 3:1, 4:1, 5:1, 6:1, and other ratios as desired. In some embodiments, all three rows of cells  254   a - c  can have the same the number of cells. Moreover, it is to be understood that fewer or greater numbers of rows of cells can be used. 
     The geometry of cells  254   a - c  can allow the cells  254   a - c  to foreshorten as the outer frame  240  is expanded. As such, one or more of cells  254   a - c  can allow the outer frame  240  to foreshorten as the outer frame  240  is expanded. Foreshortening of the outer frame  240  can be used to secure the prosthesis to intralumenal tissue in a body cavity such as tissue at or adjacent a native valve including, but not limited to, a native valve annulus and/or leaflets. For example, expansion of the outer frame  240  can allow the outer frame  240  to exert a radially outward force against the tissue at or adjacent the native valve, such as the native valve annulus and/or leaflets. 
     With continued reference to the outer frame  240  illustrated in  FIGS.  2 - 5   , the outer frame anchoring feature  244  can extend outwardly relative to the longitudinal axis of the prosthesis  200 . The outer frame anchoring feature  244  can extend at or proximate the juncture between the upper region  246  and the intermediate region  248  of the outer frame body  242 . As shown, the outer frame anchoring feature  244  can be formed from one or more anchors extending from the frame body  242  in a direction radially outward from a longitudinal axis of the outer frame  240  and/or in a direction generally toward a lower end of the outer frame  240 . The anchors of the outer frame anchoring feature  244  can be attached to the outer frame body  242  at one or more attachment points. For example, the anchors of the outer frame anchoring feature  244  can be formed from two struts of circumferentially-expansible struts  256   d  which are oriented radially outwardly and jointed together at a tip or end  244   a . The individual anchors can form a generally “V” shape. 
     In some embodiments, the outer frame anchoring feature  244  can extend in a direction that is more perpendicular to the longitudinal axis of the prosthesis  200  than parallel. As shown, the outer frame anchoring feature  244  can extend in a downward direction generally parallel to the outwardly-extending section  246   b . In some embodiments, the outer frame anchoring feature  144  can extend generally perpendicularly to the longitudinal axis  102  and/or in an upward direction. 
     In some embodiments, the lower row of cells  254   c  can be omitted. For example, the struts  256   e  can extend downwardly along a plane parallel to the longitudinal axis. These struts can extend between anchors of the inner frame anchoring feature  224 . This can advantageously allow the outer frame  240  to extend further downwardly which can beneficially allow a skirt, such as skirt  280 , to extend further downwardly and increase the effective sealing area. For example, in situations where the outer frame  240  is retained in a collapsed configuration and the inner frame anchoring feature  224  is released, the struts would not intersect with the individual anchors of the inner frame anchoring feature  224  regardless of the length of the struts. This can allow the individual anchors of the inner frame anchoring feature  224  to transition from a collapsed configuration to an expanded configuration without contacting the outer frame  240  when the outer frame  240  is retained in a collapsed configuration. 
     With reference next to  FIG.  6   , the inner frame  220  and valve body  260  of prosthesis  200  are illustrated. The inner frame  220  can include an inner frame body  222  and an inner frame anchoring feature  224 . As shown, the inner frame body  222  can have an upper region  226 , an intermediate region  228 , and a lower region  230 . As shown, the inner frame body  222  can have a generally cylindrical shape such that the diameters of the upper region  226 , the intermediate region  228 , and the lower region  230  are generally equivalent. However, it is to be understood that the diameters of the upper region  226 , the intermediate region  228 , and/or the lower region  230  can be different. For example, in some embodiments, a diameter of the intermediate region  228  can be larger than the upper region  226  and the lower region  230  such that the inner frame body  222  has a generally bulbous shape. In some embodiments, the diameter of the lower region  230  can be larger than the diameter of the upper region  226 . In other embodiments, the diameter of the upper region  226  can be larger than the diameter of the lower region  230 . 
     The diameter of the upper region  226 , intermediate region  228 , and/or lower region  230  of the inner frame body  222  may be chosen such that the inner frame body  222  is adequately spaced from the body cavity when the prosthesis  200  is positioned within the body cavity. For example, in embodiments where the prosthesis  200  is positioned within the native mitral valve, the inner frame body  222  may have a diameter which is less than the diameter of the native mitral valve annulus. In situations where the native mitral valve annulus is about 40 mm in diameter, the diameter of the inner frame body  222  can be about 30 mm. Accordingly, the diameter of the inner frame body  222  may be about 75% of the diameter of the native mitral valve annulus. 
     In some embodiments, the diameter of the inner frame body  222  may be between about 40% to about 90% of the diameter of the native valve annulus, between about 60% to about 85%, of the diameter of the native valve annulus, between about 70% to about 80% of the diameter of the native valve annulus, any other sub-range between these ranges, or any other percentage as desired. In some embodiments, the diameter of the inner frame body  222  can be in the range of about 20 mm to about 40 mm when expanded, in the range of about 25 mm to about 35 mm when expanded, in the range of about 28 mm to about 32 mm when expanded, any other sub-range within these ranges when expanded, or any other diameter when expanded as desired. Although the inner frame body  222  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  222  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     In other embodiments, the diameter of portions of the inner frame body  222  such as the upper region  226 , intermediate region  228 , and/or lower region  230  may be chosen such that the inner frame body  222  is positioned at the periphery of the body cavity. For example, in embodiments where the prosthesis  200  is positioned within the native mitral valve, the inner frame body  222  may have a diameter which is about equal to the diameter of the native mitral valve annulus. 
     With continued reference to the inner frame  220  illustrated in  FIG.  6   , the inner frame body  222  can include a plurality of struts with at least some of the struts forming cells  234   a - b . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper row of cells  234   a  and the lower row of cells  234   b  can have a diamond or generally diamond shape. The rows of cells  234   a - b  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper row of cells  234   a  can be formed from a first set of circumferentially-expansible struts  236   a  and a second set of circumferentially-expansible struts  236   b . The lower row of cells  236   b  can be formed from the second set of circumferentially-expansible struts  236   b  and a third set of circumferentially-expansible struts  236   c . The first, second, and third sets of struts  236   a - c  can have a zig-zag or undulating shape forming a repeating “V” shape. While the struts  236   a - c  are generally described and illustrated as being straight segments, it is to be understood that some or all of the struts  236   a - c  may not form entirely straight segments. For example, the struts  236   a - c  can include some curvature such that the upper and/or lower apices are curved. 
     As shown in the illustrated embodiment, the upper row of cells  234   a  and the lower row of cells  234   b  extend in a direction generally parallel to the longitudinal axis of the prosthesis  200 . There can be a row of twelve cells  234   a  and a row of twelve cells  234   b . While each of the cells  234   a - b  are shown as having the same shape as other cells  234   a - b  of the same row, it is to be understood that the shapes of cells  234   a - b  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. In some embodiments, the number of cells can correspond to the number of anchors or anchor tips forming the inner frame anchoring feature  224 . As shown, the number of cells in the upper row of cells  234   a  and the lower row of cells  234   b  can have a 1:1 correspondence with the number of anchors in the outer frame anchoring feature  224  (i.e., twelve cells in each row of cells  234   a - b  and twelve anchors for the anchoring features  224 ). It is to be understood that other ratios of numbers of cells per row to number of anchors per anchoring feature can be used such as, but not limited to, 3:1, 4:1, 5:1, 6:1, and other ratios as desired. In some embodiments, both rows of cells  234   a - b  can have different numbers of cells. Moreover, it is to be understood that fewer or greater numbers of rows of cells can be used. 
     The geometry of cells  234   a - b  can allow the cells  234   a - b  to foreshorten as the inner frame  220  is expanded. As such, one or more of cells  234   a - b  can allow the inner frame  220  to foreshorten as the inner frame  220  is expanded. As will be discussed in further detail, foreshortening of the inner frame  220  can be used to secure the prosthesis to intralumenal tissue in a body cavity such as tissue at or adjacent a native valve including, but not limited to, a native valve annulus and/or leaflets. For example, expansion of the inner frame  220  can allow the inner frame anchoring feature  224  to extend radially outward and draw closer to tissue of the body cavity, such as a native valve annulus and/or leaflets, to engage tissue of the body cavity. 
     With continued reference to the inner frame  220  illustrated in  FIG.  6   , the inner frame anchoring feature  224  can have ends or tips  224   a  positioned radially outwardly relative to the longitudinal axis of the prosthesis  200 . The inner frame anchoring feature  224  can extend at or proximate a lower end of the lower region  230  of the inner frame body  222 . As shown, the inner frame anchoring feature  224  can be formed from a plurality of individual anchors extending from the frame body  222 . The anchors can extend downwardly from one or more attachment points to the frame body  222  including, but not limited to, lower apices of cells  234   b . The anchors can bend to extend generally radially outwardly of the longitudinal axis of the prosthesis  200 . As shown in the illustrated embodiment, the anchors can extend upwardly towards an end or tip  224   a . 
     As shown in the illustrated embodiment, the tips or ends  224   a  extend upwardly in a direction generally parallel to the longitudinal axis of the prosthesis  200 . In some embodiments, the tip or end  224   a  of anchoring feature  224  can extend generally perpendicular to the longitudinal axis of the prosthesis  200 . This can beneficially increase the tissue contact area of the tip  224   a  of the anchor. This increased tissue contact area can beneficially reduce the stress applied by the tip  224   a  to tissue thereby reducing the amount of pressure and potential for trauma to the tissue. In some embodiments, the tip or ends  224   a  of the anchoring feature  224  extend radially inward towards the longitudinal axis and/or radially outward away from the longitudinal axis. 
     The tips or ends  224   a ,  244   a  as described above can advantageously provide atraumatic surfaces that may be used to contact or engage intralumenal tissue without causing unnecessary or undesired trauma to tissue. For example, the tips or ends  224   a ,  244   a  can form flat, substantially flat, curved or other non-sharp surfaces to allow the tips to engage and/or grasp tissue, without necessarily piercing or puncturing through tissue. A looped end or looped anchor may assist the frame in not getting caught up on structures at or near the treatment location. For example, each loop can be configured so that when the prosthesis  200  is deployed in-situ and the anchoring features  224 ,  244  expands away from the frame bodies  222 ,  242 , the movement of each loop from a delivered position to a deployed position avoids getting caught on the papillary muscles. As shown in the illustrated embodiment, the inner frame anchoring feature  224  can include a lacrosse-head-shaped tip or end  224   a . The outer frame anchoring feature  244  can include tips or ends  244   a  having a “U” shape or rounded shape. 
     As shown in the illustrated embodiment, the anchoring features  224 ,  244  can include twelve individual anchors; however, it is to be understood that a greater number or lesser number of individual anchors can be used. For example, the number of individual anchors can be chosen as a multiple of the number of commissures for the valve body  260 . As such, for a prosthesis  200  with a valve body  260  having three commissures, the inner frame anchoring feature  224  and/or the outer frame anchoring feature  244  can have three individual anchors (1:1 ratio), six individual anchors (2:1 ratio), nine individual anchors (3:1 ratio), twelve individual anchors (4:1 ratio), fifteen individual anchors (5:1 ratio), or any other multiple of three. It is to be understood that the number of individual anchors need not correspond to the number of commissures of the valve body  260 . Moreover, while the prosthesis  200  includes anchoring features  224 ,  244  with twelve anchors each, it is to be understood that a greater number of anchors or a lesser number of anchors can be used. In some embodiments, instead of a 1:1 correspondence between the number of anchors in the inner frame anchoring feature  224  and the outer frame anchoring feature  244  (i.e., twelve anchors each), other ratios can be used. For example, a 1:2 or a 1:3 correspondence between the anchors, are possible such that the inner frame anchoring feature  224  or the outer frame anchoring feature  244  have fewer anchors than the other anchoring feature. 
     With continued reference to the inner frame  220  illustrated in  FIG.  6   , the inner frame anchoring feature  224  can include covers and/or cushions  238  to surround or partially surround at least a portion of the inner frame anchoring feature  224 , such as the tips or ends  224   a . The covers and/or cushions  238  can be similar to those described in U.S. Publication No. 2015/0328000, which has been incorporated by reference in its entirety. The covers and/or cushions  238  can either fit snuggly around the tips  224   a  of the inner frame anchoring feature  224  or can have extra padding so that the covers extend radially away from the inner frame body  222 . As shown in the illustrated embodiment, covers and/or cushions  238  are attached to a subset of anchors of the inner frame anchoring feature  224  such that a cover and/or cushion  238  is used on every third anchor. In some embodiments, the outer frame anchoring feature  244  can include covers and/or cushions to surround or partially surround at least a portion of the outer frame anchoring feature  244 , such as the tips or ends  244   a . 
     It is to be understood that greater or fewer numbers of covers and/or cushions  238  can be used with anchors of the inner frame anchoring feature  224  and/or the outer frame anchoring feature  244 . For example, a cover and/or cushion  238  can be used on every other anchor such that there is a 1:2 ratio of covers and/or cushions  238  to anchors. As another example, a cover and/or cushion  238  can be used on every anchor (as shown in  FIGS.  2 - 5   ). In some embodiments, all of the anchors can have the covers and/or cushions with some of the anchors having less cushioning than others. In some embodiments, all of the anchors can have the padded covers. In other embodiments, all of the anchors can have the snuggly fitting cushions. In other embodiments, the configuration of the covers and/or cushions can differ between the inner frame anchoring feature  224  and the outer frame anchoring feature  244 . 
     The cover and/or cushion  238  can be formed from a deformable material. When the top portion of the cover and/or cushion  238  is subject to pressure due to a downwardly directed force, the cover and/or cushion  238  can compress and expand laterally outward. Such a force may be exerted upon the cover and/or cushion  238  when the cover and/or cushion  238 , for example, when the cover and/or cushion  238  contacts a ventricular side of the mitral valve annulus during systole. The compression and lateral expansion of cover and/or cushion  238  can increase the surface area of the cover and/or cushion  238  in contact with the tissue, thereby exerting less pressure on the tissue and reducing the potential for trauma. 
     With continued reference to the anchoring features  224 ,  244  illustrated in  FIGS.  2 - 6   , the tips or ends  224   a  of the inner frame anchoring feature  224  can be generally circumferentially aligned with respect to the tips or ends  244   a  of the outer frame anchoring feature  244  meaning that the tips or ends  224   a  of the inner frame anchoring feature  224  are aligned, in a circumferential direction, with the tips or ends  244   a  of the outer frame anchoring feature  244 . In other embodiments (not shown), the tips or ends  224   a  of the inner frame anchoring feature  224  and the tips or ends  244   a  of the outer frame anchoring feature  244  can be circumferentially offset or staggered meaning that the tips or ends  224   a  of the inner frame anchoring feature  224  are not aligned, in a circumferential direction, with the tips or ends  244   a  of the outer frame anchoring feature  244 . 
     Preferably, each of the anchoring features  224 ,  244  are positioned or extend generally radially outwardly from the prosthesis  200  so that the anchor tips or ends  224   a ,  244   a  are generally spaced away or radially outward from the rest of the frame bodies  222 ,  242  and from the one or more attachment points or bases of the anchors of the anchoring features  224 ,  244 . For example, the anchor tips  224   a ,  244   a  may be located radially outward from the intermediate region  248  and/or lower region  250  of the outer frame body  242 , with the tips  224   a ,  244   a  being axially spaced from one another. 
     As shown in the illustrated embodiment, at least some of the anchoring features, such as anchoring feature  244 , can extend to a radial distance from an exterior surface of the intermediate region  248  and/or lower region  250  of the outer frame body  242  that is about 110% or more of the expanded diameter of the intermediate region  248  of the outer frame body  242  at the plane of tips  244   a . At least some of the anchoring features, such as anchoring feature  224 , can extend to a radial distance from an exterior surface of the intermediate region  248  of the outer frame body  242  that is slightly greater than the expanded diameter of the intermediate region  248  and/or the lower region  250  of the outer frame body  242  at the plane of tips  224   a . As shown, the tips  224   a  can be positioned such that the tips  224   a  contact an exterior of the outer frame body  242 . As will be discussed in further detail below, this can beneficially pinch or grasp tissue of the body cavity therebetween. For example, in instances where the prosthesis  200  is used at a native mitral valve, native leaflets and/or portions of the native mitral valve annulus can be pinched or grasped between the anchoring feature  224  and the intermediate region  248  and/or lower region  250  of the outer frame body  242 . 
     In some embodiments, all of the anchors of the inner frame anchoring feature  224  and/or all of the anchors of the outer frame anchoring feature  244  extend at least to this radial distance. In other embodiments, fewer than all of the anchors of the inner frame anchoring feature  224  and/or all of the anchors of the outer frame anchoring feature  244  extend to this radial distance. The outermost diameter of the inner frame anchoring feature  224  and/or the outer frame anchoring feature  244  may be greater than the diameter of frame bodies  222 ,  224  as described above and may be in the range of about 35 mm to about 70 mm when expanded, in the range of about 35 mm to about 60 mm when expanded, in the range of about 40 mm to about 60 mm when expanded, in the range of about 45 mm to about 50 mm when expanded, any sub-range within these ranges when expanded, or any other diameter as desired. 
     As shown, the inner frame anchoring feature  224  can be positioned to be not as far radially outward as the outer frame anchoring feature  244 . However, it is to be understood that in other embodiments, the inner frame anchoring feature  224  and the outer frame anchoring feature  244  can extend radially outward from the longitudinal axis of the prosthesis  200  to about the same radial dimension or the outer frame anchoring feature  244  can be positioned to be not as far radially outward as the inner frame anchoring feature  224 . Such configurations may be advantageous in positioning and securing the prosthesis in a native valve annulus or other body location. 
     In some embodiments, individual anchors can extend radially outwardly from the frame at an anchor base and terminate at an anchor tip. The individual anchors can be connected to the frame at one of many different locations including apices, junctions, other parts of struts, etc. Moreover, the anchors forming the anchoring features  224 ,  244  can comprise first, second, third, or more spaced apart bending stages along the length of each anchor. Further details that may be incorporated and/or interchanged with the features described herein are disclosed in U.S. Publication Nos. 2014/0277422, 2014/0277427, 2014/0277390, and 2015/0328000, and U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, which have been incorporated by reference herein. 
     One or both anchoring features  224 ,  244  can contact or engage a native valve annulus, such as the native mitral valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. In some embodiments, one or both anchoring features  224 ,  244  do not contact or engage, or only partially contact or engage, a native valve annulus, such as the native mitral valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. However, it is to be understood that in some embodiments, when the prosthesis  200  is used for a replacement mitral valve prosthesis, during diastole and/or systole, both the inner frame anchoring feature  224  and the outer frame anchoring feature  244  can be sized to contact or engage the native mitral valve annulus. 
     The anchoring features  224 ,  244  and anchor tips  224   a ,  244   a  are preferably located along the prosthesis  200  with at least part of the foreshortening portion positioned between the anchoring features  224 ,  244  so that a portion of the anchoring features  224 ,  244  will move closer together with expansion of the prosthesis  200 . This can allow the anchoring features  224 ,  244  to close in on opposite sides of the native mitral annulus to thereby secure the prosthesis at the mitral valve. In some embodiments, the anchoring features  224 ,  244  can be positioned such that the anchoring features  224 ,  244  do not contact opposing portions of the native mitral annulus at the same time. For example, when the prosthesis  200  is used for a replacement mitral valve prosthesis, during at least systole, in some embodiments the inner frame anchoring feature  224  is sized to contact or engage the native mitral valve annulus whereas the outer frame anchoring feature  244  is sized to be spaced from the native mitral valve annulus. This can be beneficial when outer frame anchoring feature  244  is used to provide stabilization and help align the prosthesis. In some embodiments, the anchoring features  224 ,  244  can be positioned such that the anchoring features  224 ,  244  grasp opposite side of the native mitral annulus. 
     While the anchoring features  224 ,  244  have been illustrated as extending from the lower end of the lower region  230  of the inner frame body  222  and at a junction between the upper region  246  and the intermediate region  248  of the outer frame body  242  respectively, it is to be understood that the anchoring features  224 ,  244  can be positioned along any other portion of the prosthesis  200  as desired. Moreover, while two anchoring features  224 ,  244  have been included in the illustrated embodiment, it is to be understood that a greater number or lesser number of sets of anchoring features can be utilized. 
     With reference back to the inner frame  220  illustrated in  FIG.  6   , the inner frame  220  can include a set of locking tabs  232  extending the at or proximate an upper end of the upper region  226  of the inner frame body  222  such as upper apices of cells  234   a . As shown, the inner frame  220  can include twelve locking tabs  232 , however, it is to be understood that a greater number or lesser number of locking tabs can be used. The locking tabs  232  can extend generally upwardly from the upper region  226  of the inner frame body  222  in a direction generally aligned with the longitudinal axis of the prosthesis  200 . As shown in the illustrated embodiment, the locking tabs  232  can include a longitudinally-extending strut  232   a . At an upper end of the strut  232   a , the locking tab  232  can include an enlarged head  232   b . As shown, the enlarged head  232   b  can have a semi-circular or semi-elliptical shape forming a “mushroom” shape with the strut  232   a . The locking tab  232  can include an eyelet  232   c  which can be positioned through the enlarged head  232   b . It is to be understood that the locking tab  232  can include an eyelet at other locations, or can include more than a single eyelet. 
     The locking tab  232  can be advantageously used with multiple types of delivery systems. For example, the shape of the struts  232   a  and the enlarged head  232   b  can be used to secure the inner frame  220  to a “slot” based delivery system. The eyelets  232   c  can be used to secure the inner frame  220  to a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery of the inner frame  220  and the prosthesis  200 . This can advantageously facilitate recapture and repositioning of the inner frame  220  and the prosthesis  200  in situ. In some embodiments, the prosthesis  220  can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which are hereby incorporated by reference and made a part of this specification. 
     While the locking tabs  232  have been described as being attached to the inner frame body  222 , it is to be understood that the locking tabs  232  can be attached to other portions of the prosthesis  200  such as, but not limited to, the outer frame body  242 . For example, in some embodiments, the locking tabs  232  can extend from an upper end of an upper region  246  of the outer frame body  242 . Moreover, it is to be understood that portions of, or the entirety of, the locking tabs  232  can be omitted. For example, in some embodiments, the strut  232   a  can be omitted such that the enlarged head  232   b  and eyelet  232   c  are positioned at an upper end of the upper region  226  of the inner frame body  222 , such as at upper apices of cell  234   a . 
     With reference next to the valve body  260  illustrated in  FIG.  6   , the valve body  260  can be positioned within the inner frame  220 . The valve body  260  can be a replacement heart valve which includes a plurality of valve leaflets  262 . The valve leaflets  262  can include a first edge  264 , second edge  266 , and tabs  268  (as shown in  FIG.  5   ) for attaching the valve leaflets  262  together at commissures of the valve body  260 . The tabs  268  can be used to secure the valve leaflets  262  to the inner frame  220 . The first edge  264  can be an arcuate edge and can be generally fixed in position relative to the frame  220 . The second edge  266  can be a freely moving edge which can allow the valve body  260  to open and close. 
     The plurality of valve leaflets  262  can function in a manner similar to the native mitral valve, or to any other valves in the vascular system as desired. The plurality of valve leaflets  262  can open in a first position and then engage one another to close the valve in a second position. The plurality of valve leaflets  262  can be made to function as a one way valve such that flow in one direction opens the valve and flow in a second direction opposite the first direction closes the valve. For example, as shown in the illustrated embodiment, the valve body  260  can open allow to blood to flow through the valve body  260  in a direction from an upper end to a lower end. The valve body  260  can close to inhibit blood flow through the valve body  260  in a direction from the lower end to the upper end. In situations where the prosthesis  200  is oriented such that an upper end is a proximal end and a lower end is a distal end, the valve body  260  can be positioned such that the valve body  260  can open to allow blood to flow through the valve body  260  in a proximal-to-distal direction and close to inhibit blood flow in a distal-to-proximal direction. The valve body  260  can be constructed so as to open naturally with the beating of the heart. For example, the valve body  260  can open during diastole and close during systole. The valve body  260  can replace a damaged or diseased native heart valve such as a diseased native mitral valve. 
     The valve body  260  can include a liner  270 . The liner  270  can be used to assist with fluid flow through and/or around the prosthesis  200 , such as through and around the inner frame  220  and the valve leaflets  262 . The liner  270  can surround at least a portion of the valve leaflets  262  and be connected to one or more of the valve leaflets  262 . For example, as shown in the illustrated embodiment, the one or more valve leaflets  262  can be attached to the liner  270  along the first edge  264  of the valve leaflets  262 . 
     As shown in the illustrated embodiment, the liner  270  can be positioned within the interior of the inner frame  220  and can form an inner wall of the prosthesis  200 . For example, the liner  270  can be positioned such that the liner  270  is radially inward, relative to the longitudinal axis of the prosthesis  200 , from the struts  236   a - c  of the inner frame  220 . In this manner, the fluid pathway towards the valve leaflets  262  can be relatively smooth. It is also contemplated that the liner  270  can at least be partially positioned along an exterior of the inner frame  220  and/or outer frame  240  such that at least a portion of the liner  270  is radially outward, relative to the longitudinal axis of the prosthesis  200 , from struts of the inner frame  220  and/or outer frame  240 . As shown in the illustrated embodiment, the liner  270  can be positioned along an upper or inlet side of the inner frame  220 . The liner  270  can extend from the first edge  264  of the valve leaflets  262  towards the upper end of the inner frame  220 . The liner  270  can also extend below the first edge  264  of the valve leaflet  262  towards the lower end of the inner frame  220 . The liner  270  can also be made to move with foreshortening portions of the inner frame  220 . 
     In some embodiments, the liner  270  can extend the entire length of the inner frame  220  or the inner frame body  222 . In other embodiments, it can extend along only part of the length of the inner frame body  222  as shown. In some embodiments, the ends of the valve leaflets  262  can coincide with ends of the liner  270 . In addition, one or more of the ends of the inner frame body  222  can coincide with the ends of the liner  270 . As shown in the illustrated embodiment, an end  272  of the liner  270  can be positioned between the upper end of the inner frame  220  and the valve leaflets  262 . The end  272  of the liner  270  can extend above an upper end of the inner frame body  222  and extend along a portion of the locking tabs  232 . In some embodiments, the end  272  of the liner  270  can be positioned at or proximate an uppermost portion of the first or arcuate edge  264  of the valve leaflet  262  below the upper end of the inner frame body  222 . 
     Other shapes and configurations can also be used for the valve body  260 . In some embodiments, the liner  270  may extend along the length of the leaflets, but is not connected to them. In the illustrated embodiment, the liner  270  is attached to the inner frame  220  and at least a portion of the leaflets  262 , such as the first or arcuate edge  264 , is attached to the liner  270 . Portions of the valve leaflets  262 , such as the portions of the first edge  264  and/or tabs  268 , can also be attached to the inner frame  220 . The liner  270  and/or the valve leaflets  262  can be attached to the inner frame  220  or to each other using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. 
     The liner  270  can be constructed in multiple different ways. The liner  270  can be made a layer of resilient material, such as such as knit polyester (e.g., polyethylene terephthalate (PET), polyvalerolactone (PVL)) or any other biocompatible material such as those which are wholly or substantially fluid impermeable, flexible, stretchable, deformable, and/or resilient. In some embodiments, the liner  270  can be made from a material that is more flexible than the valve leaflet material. The upper and/or lower end, such as end  272 , of the liner  270  can be straight, curved, or have any other desired configuration. For example, as shown in the illustrated embodiment, the liner  270  can have a straight edge forming the end  272 . In other embodiments, the end  272  can be patterned to generally correspond to the undulations at one end of the inner frame  220 . The liner  270  can be formed of one piece or multiple pieces.E 
     In another embodiment of the liner  270 , the end can extend past the inner frame  220  and can be wrapped around it. Thus, the liner  270  can extend from the interior of the inner frame  220  to the exterior of the inner frame  220 . The liner  270  can extend completely around the inner frame  220  for ¼, ⅓, ½, or more of the length of inner frame  220 . 
     With reference next to the skirt  280  illustrated in  FIGS.  2 - 5   , the skirt  280  can be positioned around and secured to at least a portion of the exterior of the prosthesis  200  such as, but not limited to, the inner frame  220  and/or the outer frame  240 . The skirt  280  can be annular and can extend entirely circumferentially around the prosthesis  200 . The skirt  280  can prevent or inhibit backflow of fluids around the prosthesis  200 . For example, with the skirt  280  positioned annularly around an exterior of the prosthesis  200 , the skirt  280  can create an axial barrier to fluid flow exterior to the prosthesis  200  when deployed within a body cavity. As shown, the skirt  280  can seal against at least a portion of tissue surrounding the body cavity. In addition, the skirt  280  can encourage tissue in-growth between the flap assembly  280  and natural tissue of the body cavity. This may further help to prevent leakage of blood flow around the prosthesis  200 . 
     The skirt  280  can have an upper region  282 , an intermediate region  284 , and a lower region  286 . The upper region  282  of the skirt  280  can extend along a portion of the exterior of the outer frame  240  such as the upper region  246  of the outer frame  240 . The intermediate region  284  of the skirt  280  can extend along a portion of the exterior of the outer frame  240  such as the intermediate region  248  of the outer frame  240 . The lower region  286  of the skirt  280  can extend along a portion of the exterior of the outer frame  240  such as the lower region  250  of the outer frame  240 . While the skirt  280  is shown extending along the exterior of the outer frame  240 , it is to be understood that portions of, or the entirety of, the skirt  280  can extend along an interior of the outer frame. It is also to be understood that while the skirt  280  is shown tautly attached to the outer frame  240 , a portion of, or the entirety of, the skirt  280  can be loosely attached such that a portion of, or the entirety of, the skirt  280  is movable relative to the outer frame  240 . 
     The upper end of the skirt  280  can be positioned at or proximate an upper end of the outer frame body  242  and/or an upper end of the inner frame body  222 . In some embodiments, the upper end of the skirt  280  can be attached to the end  272  of the liner  270  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. The lower end of the lower region  286  of the skirt  280  can be positioned at or proximate a lower end of the lower region  250  of the outer frame body  242 . The skirt  280  may be attached to the outer frame  240  and/or inner frame  220  using any fasteners and/or techniques described herein. For example, portions of the skirt  280  can be attached to struts and/or anchoring features of the outer frame  240  and/or inner frame  220  via sutures. 
     As shown in the illustrated embodiment, the lower end of the lower region  286  of the skirt  280  can be provided with a generally straight edge with extends circumferentially around the outer frame body  242  and/or inner frame body  222 . It is to be understood that other configurations, such as a curved edge, can also be used as desired. In some embodiments, the lower end of the lower region  286  of the skirt  280  can follow the shape of the struts along the lower end of the lower region  250  of the outer frame body  242 . 
     In some embodiments, the skirt  280  can be formed from a material such as knit polyester (e.g., polyethylene terephthalate (PET), polyvalerolactone (PVL)) or any other biocompatible material such as those which are wholly or substantially fluid impermeable, flexible, stretchable, deformable, and/or resilient. The skirt  280  and/or the liner  270  may be made from the same or similar materials. As shown in the illustrated embodiment, the skirt  280  can be formed as separate components. The components can be attached together using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. For example, the upper region  282  can be a first component and the intermediate region  284  and/or lower region  286  can be a second component. In other embodiments, skirt  280  can be integrally or monolithically formed. For example, in some embodiments, the upper region  282  of the skirt  280  and the intermediate region  284  and/or lower region  286  can be integrally or monolithically formed as a single component. 
     In some embodiments, the outer frame  240  can be attached to the inner frame  220  at one or more attachment points using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the inner frame  220  and the outer frame  240 ), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. 
     The outer frame  240  can be attached to the inner frame  220  by attaching the skirt  280  to the inner frame  220  and/or portions of the valve body  260 , such as the liner  270  using any mechanism or technique described herein. In some embodiments, the outer frame  240  can be tautly attached to the inner frame  220  such that little to no relative movement between the outer frame  240  and the inner frame  220  occurs at the one or more attachment points of the outer frame  240  to the inner frame  220 . For example, the outer frame  240  can be tautly attached to the inner frame  220  and/or the skirt  280  can be attached to the inner frame  220  and/or valve body  260  with little to no slack. In other embodiments, the outer frame  240  can be loosely attached to the inner frame  220  such that some relative movement between the outer frame  240  and the inner frame  220  occurs at the one or more attachment points of the outer frame  240  to the inner frame  220 . For example, the outer frame  240  can be loosely attached to the inner frame  220  and/or the skirt  280  can be attached to the inner frame  220  and/or valve body  260  with slack to permit relative movement between the outer frame  240  and the inner frame  240 . 
     With reference next to  FIGS.  7 - 8   , an embodiment of an outer frame  300  in an expanded configuration is illustrated. The outer frame  300  can include an outer frame body  302 . A longitudinal axis of the outer frame  300  may be defined as the central axis that extends through the center of the outer frame  300  between the upper and lower ends of the outer frame  300 . As shown, the outer frame body  302  can have an upper region  304 , an intermediate region  306 , and a lower region  308 . 
     When in an expanded configuration such as in a fully expanded configuration, the outer frame body  302  can have a bulbous shape with the intermediate region  306  being larger than the upper region  304  and the lower region  308 . The bulbous shape of the outer frame body  302  can advantageously allow the outer frame body  302  to engage a native valve annulus, native valve leaflets, or other body cavity, while spacing the inlet and outlet from the heart or vessel wall. This can help reduce undesired contact between the prosthesis in which the outer frame  300  is used and the heart or vessel, such as the atrial and ventricular walls of the heart. The bulbous shape can further enhance securement of the outer frame body  302  to the body cavity. For example, in some embodiments, the bulbous shape can allow the intermediate region  306  to extend further radially outward compared to an anchoring feature, such as lower frame anchoring features  124 ,  224 . In this manner, the intermediate region  306  can exert a greater radial force on tissue of the body cavity and/or can more completely conform to the tissue of the body cavity, such as the native valve annulus and/or native leaflets. 
     The upper region  304  of the outer frame body  302  can include a generally longitudinally-extending section  304   a  and an outwardly-extending section  304   b . The outwardly-extending section  304   b  can extend radially outwardly away from the longitudinal axis of the outer frame  300 . In some embodiments, the outwardly-extending section  246   b  can extend in a direction that is more perpendicular to the longitudinal axis  202  than parallel and/or in a downward direction from the longitudinally-extending section  304   a . However, it is to be understood that the outwardly-extending section  304   b  can extend generally perpendicularly to the longitudinal axis and/or in an upward direction from the longitudinally-extending section  304   a . Moreover, it is to be understood that the longitudinally-extending section  304   a  can be omitted. 
     At the juncture between the longitudinally-extending section  304   a  and the outwardly-extending section  304   b , the outer frame body  302  can include a bend  310 . The bend  310  can be about a circumferential axis such that the outwardly-extending section  304   b  extends in a direction more perpendicular to the longitudinal axis of the outer frame  300  than the longitudinally-extending section  304   a . In some embodiments, the bend  310  can generally form an arc with an angle between about 20 degrees to about 90 degrees. For example, as shown in the illustrated embodiment, the arc can have an angle of about 60 degrees. In some embodiments, the bend  310  can form an arc with an angle between about 30 degrees to about 60 degrees. The radius of curvature of the arc may be constant such that the bend  310  forms a circular arc or may differ along the length of the bend  310 . 
     In some embodiments, the outwardly-extending section  304   b  can form an angle of between about 20 degrees to about 70 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , an angle of between about 30 degrees to about 60 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , an angle of between about 40 degrees to about 50 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , an angle of about 30 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , any subrange within these ranges, or any other angle as desired. In some embodiments, the outwardly-extending section  304   b  can form an angle of less than 70 degrees with a plane orthogonal to the longitudinal axis of the outer frame  200 , an angle of less than 55 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , an angle of less than 40 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , an angle of less than 25 degrees with a plane orthogonal to the longitudinal axis of the outer frame  300 , or less than any other angle as desired. 
     The intermediate region  306  of the outer frame body  302  can extend generally downwardly from the outwardly-extending section  304   b  of the upper region  304 . As shown, the intermediate region  306  can have a generally bulbous shape with a greater diameter along a portion between the upper and lower ends of the intermediate region  306 . However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be the same such that the intermediate region  306  forms a generally cylindrical shape. In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. 
     Although the outer frame body  302  has been described and illustrated as having a circular cross-sections, it is to be understood that all or a portion of the outer frame body  302  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     At the juncture between the upper region  304  and the intermediate region  306 , the outer frame body  302  can include a bend  312 . The bend  312  can be about a circumferential axis such that the intermediate region  306  extends in a direction more parallel to the longitudinal axis of the outer frame  300  than the outwardly-extending section  304   b  of the upper region  304 . In some embodiments, the bend  312  can generally form an arc with an angle between about  20  degrees to about 90 degrees. For example, as shown in the illustrated embodiment, the arc can have an angle of about 60 degrees. In some embodiments, the bend  312  can form an arc with an angle between about 30 degrees to about 60 degrees. The radius of curvature of the arc may be constant such that the bend  312  forms a circular arc or may differ along the length of the bend  312 . 
     The lower region  308  of the outer frame body  302  can extend generally downwardly from the lower end of the intermediate region  306 . As shown, the lower region  308  of the outer frame body  302  can have a decreasing diameter from an upper end of the lower region  308  to a lower end of the lower region  308  such that the lower region  308  is inclined or curved radially inwards towards the longitudinal axis of the outer frame  300 . This radially inward incline or curve of the lower region  308  can facilitate capture of native valve leaflets between the outer frame  300  and other portions, such as an anchoring feature, of the prosthesis in which the outer frame  300  is used. Moreover, this radially inward inclined or curve of the lower region  308  can reduce or inhibit potential trauma to tissue of the body cavity, such as the native leaflets and/or native valve annulus. For example, the curvature and/or inclination of the lower region  308  can be chosen to better conform to the curvature of tissue positioned between the outer frame  300  and an anchoring feature of another portion of a prosthesis in which the outer frame  300  is used. 
     The lower region  308  can be curved and/or inclined towards the longitudinal axis of the frame  300  such that the lower ends of the lower region  308  can extend in a direction that is between about 20 degrees to about 80 degrees with respect to a plane parallel to the longitudinal axis of the frame  300 , between about 25 degrees to about 70 degrees with respect to a plane parallel to the longitudinal axis of the frame  300  between about 30 degrees to about  60  degrees with respect to a plane parallel to the longitudinal axis of the frame  300 , about 30 degrees with respect to a plane parallel to the longitudinal axis of the frame  300 . The lower region  308  can be curved and/or inclined towards the longitudinal axis of the frame  300  such that the lower ends of the lower region  308  can extend in a direction generally perpendicular to the longitudinal axis of the frame  300 . 
     In some embodiments, the outer frame body  302  in an expanded configuration can have a diameter at its widest portion of between about 30 mm to about 60 mm, between about 35 mm to about 55 mm, about 40 mm, any sub-range within these ranges, or any other diameter as desired. In some embodiments, the outer frame body  302  in an expanded configuration can have a diameter at its narrowest portion between about 20 mm to about 40 mm, any sub-range within these ranges, or any other diameter as desired. In some embodiments, the outer frame body  302  in an expanded configuration can have a diameter at a lower end of the lower region  308  between about 20 mm to about 40 mm, any sub-range within these ranges, or any other diameter as desired. In some embodiments, in an expanded configuration, the ratio of the diameter of the outer frame body  302  at its widest portion to the diameter of the frame body  302  at its narrowest portion can be about 3:1, about 5:2, about 2:1, about 3:2, about 4:3, any ratio within these ratios, or any other ratio as desired. 
     The outer frame body  302  can have an axially compact configuration relative to the radial dimension. In some embodiments, the outer frame body  302  in an expanded configuration can have an the axial dimension between the upper and lower ends of the outer frame body  302  (i.e., the “height” of the outer frame body  302 ) of between about 10 mm to about 40 mm, between about 18 mm to about 30 mm, about 20 mm, any sub-range within these ranges, or any other height as desired. For example, the ratio of the diameter of the largest portion of the outer frame body  302  to the height of the outer frame body  302  when the frame is in its expanded configuration can be about 3:1, about 5:2, about 2:1, about 3:2, about 4:3, about 13:10, about 5:4, or about 1:1. Thus, in some embodiments the width at the largest portion of the outer frame body  302  can be greater than the height of the outer frame body  302 . 
     With continued reference to the outer frame  300  illustrated in  FIGS.  7 - 8   , the outer frame body  302  can include a plurality of struts with at least some of the struts forming cells  314   a - c . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper row of cells  314   a  can have an irregular hexagonal shape such as the illustrated “heart” shape. The cell  314   a  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper portion of cells  314   a  can be formed from a set of circumferentially-expansible struts  316   a  having a zig-zag or undulating shape forming a repeating “V” shape. The circumferentially-expansible struts  316   a  can be inclined or curved radially outwards away from the longitudinal axis of the outer frame  300  such that an upper portion of the struts  316   a  is positioned closer to the longitudinal axis of the outer frame  300  than the lower portion of the struts  316   a . As shown in the illustrated embodiment, the circumferentially-expansible struts can incorporate bend  310  of the outer frame body  302 . 
     The lower portion of cells  314   a  can be formed from a set of circumferentially-expansible struts  316   b  having a zig-zag or undulating shape forming a repeating “V” shape. The lower tips or ends of the circumferentially-expansible struts  316   b  can be at or proximate the junction of the upper region  304  and the intermediate region  306 . As shown in the illustrated embodiment, the circumferentially-expansible struts can incorporate part of bend  312  of the outer frame body  302 . One or more of the upper ends or tips of the circumferentially-expansible struts  316   b  can be a “free” apex which is not connected to a strut. For example, as shown in the illustrated embodiment, every other upper end or tip of circumferentially-expansible struts  316   b  is a free apex. However, it is to be understood that other configurations can be used. For example, every upper apex along the upper end can be connected to a strut. 
     The middle and/or lower rows of cells  314   b - c  can have a different shape from the cells  314   a  of the first row. The middle row of cells  314   b  and the lower row of cells  314   c  can have a diamond or generally diamond shape. The diamond or generally diamond shape can be formed via a combination of struts. The upper portion of cells  314   b  can be formed from the set of circumferentially-expansible struts  316   b  such that cells  314   b  share struts with cells  314   a . The lower portion of cells  314   b  can be formed from a set of circumferentially-expansible struts  316   c . As shown in the illustrated embodiment, one or more of the circumferentially-expansible struts  316   c  can extend generally in a downward direction and can incorporate part of bend  312  of the outer frame body  302 . For example, the one or more circumferentially-expansible struts  316   c  can be curved such that an upper portion of the struts  316   c  are positioned closer to the longitudinal axis of the outer frame  300  than a portion of the struts  316   c  positioned between the upper and lower ends of the struts  316   c . In some embodiments, one or more of the circumferentially-expansible struts  316   c  can extend radially outward from the longitudinal axis of the outer frame  300 . 
     The upper portion of cells  314   c  can be formed from the set of circumferentially-expansible struts  316   c  such that cells  314   c  share struts with cells  314   b . The lower portion of cells  314   c  can be formed from a set of circumferentially-expansible struts  316   d . Circumferentially-expansible struts  316   d  can extend generally in a downward direction. As shown in the illustrated embodiment, the circumferentially-expansible struts  316   e  can be inclined or curved towards the longitudinal axis of the outer frame  300  such that an upper portion of the struts  316   d  can be positioned closer to the longitudinal axis of the outer frame  300  than the lower portion of the struts  316   d . In some embodiments, the circumferentially-expansible struts  316   d  can extend in a direction generally parallel to the longitudinal axis of the outer frame  300 . 
     As shown in the illustrated embodiment, there can be a row of twelve cells  314   a , a row of twenty-four cells  314   b , and a row of twenty-four cells  314   c . While each of the cells  314   a - c  are shown as having the same shape as other cells  314   a - c  of the same row, it is to be understood that the shapes of cells  314   a - c  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. In some embodiments, the number of cells can correspond to the number of anchors or anchor tips forming the anchoring features of the prosthesis in which the outer frame  300  is used such as, but not limited to, a 1:1 correspondence, a 2:1 correspondence, a 3:1 correspondence, a 4:1 correspondence, a 5:1 correspondence, a 6:1 correspondence, and other ratios as desired. In some embodiments, all three rows of cells  314   a - c  can have the same the number of cells. Moreover, it is to be understood that fewer or greater numbers of rows of cells can be used. 
     The geometry of cells  314   a - c  can allow the cells  314   a - c  to foreshorten as the outer frame  300  is expanded. As such, one or more of cells  314   a - c  can allow the outer frame  300  to foreshorten as the outer frame  300  is expanded. Foreshortening of the outer frame  300  can be used to secure the prosthesis to intralumenal tissue in a body cavity such as a native valve including, but not limited to, a native valve annulus and/or leaflets. For example, expansion of the outer frame  300  can allow the outer frame  300  to exert a radially outward force against the tissue at or adjacent the native valve, such as the native valve annulus and/or leaflets. 
     As shown in the illustrated embodiment, the outer frame  300  can include tabs  318  extending from a portion of the frame  300  such as an upper end of the frame body  302 . The tabs  318  can include an eyelet  320 . The tab  318  can be advantageously used to couple the outer frame  300  to an inner frame, such as inner frames  120 ,  220 , of the prosthesis in which the outer frame  300  is used. For example, a suture can be passed through the eyelet  320  for coupling to an inner frame. In some embodiments, the tabs  318  can be used to couple to other components of a prosthesis in which the outer frame  300  is used such as, but not limited to, a valve body and/or a skirt. 
     In some embodiments, the tab  318  can be advantageously used to couple the outer frame  300  with multiple types of delivery systems. For example, the shape of the tab  318  can be used to secure the outer frame  300  to a “slot” based delivery system. The eyelets  320  can be used to secure the outer frame  300  to a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery of the outer frame  300  and the prosthesis. This can advantageously facilitate recapture and repositioning of the outer frame  300  and the prosthesis in situ. In some embodiments, the outer frame  300  and prosthesis can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which have been incorporated by reference herein. In some embodiments, a tab can be positioned at an end of a strut similar to locking tabs  232 . 
     With reference next to  FIGS.  9 - 10   , an embodiment of an inner frame  400  in an expanded configuration is illustrated. The inner frame  400  can include an inner frame body  402 . The inner frame  400  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of inner frame  220  described above in connection with  FIGS.  2 - 6   . As such, reference should be made to the description of inner frame  220  above. 
     As shown in the illustrated embodiment, the inner frame  400  can include tabs  404  extending from a portion of the inner frame  400 , such as an upper end of the frame body  402 . The inner frame  400  can include an eyelet  406 . The eyelet  406  can be advantageously used to couple the inner frame  400  to an outer frame, such as outer frames  120 ,  220 ,  300 , of the prosthesis in which the inner frame  400  is used. For example, a suture can be passed through the eyelet  406  for coupling to an eyelet  320  of the outer frame  300 . In some embodiments, the eyelet  406  can be used to couple to other components of a prosthesis in which the inner frame  400  is used such as, but not limited to, a valve body and/or a skirt. 
     In some embodiments, the tab  404  can be advantageously used to couple the inner frame  400  with multiple types of delivery systems. For example, the shape of the tab  404  can be used to secure the inner frame  400  to a “slot” based delivery system. The eyelets  406  can be used to secure the inner frame  400  to a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery of the inner frame  400  and the prosthesis. This can advantageously facilitate recapture and repositioning of the inner frame  400  and the prosthesis in situ. In some embodiments, the inner frame  400  and prosthesis can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which have been incorporated by reference herein. In such embodiments, the tab  404  may be omitted to advantageously the axial dimension between the upper end and the lower end of the inner frame  400  (i.e., the “height” of the inner frame  400 ). 
     With reference next to  FIG.  33   , an embodiment of a prosthesis  1500  in an expanded configuration is illustrated. The prosthesis  1500  can include an inner frame  1520 , an outer frame  1540 , a valve body  1560 , and one or more skirts, such as an outer skirt  1580  and an inner skirt  1590 . The prosthesis  1500  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein such as, but not limited to prosthesis  100 . 
     With reference first to the inner frame  1520 , the inner frame  1520  can include an inner frame body  1522  and an inner frame anchoring feature  1524 . The inner frame body  1522  can have an upper region  1522   a , an intermediate region  1522   b , and a lower region  1522   c . As shown, the inner frame body  1522  can have a generally bulbous shape such that the diameters of the upper region  1522   a  and the lower region  1522   c  are less than the diameter of the intermediate region  1522   b . The diameter of the upper region  1522   a  can be less than the diameter of the lower region  1522   c . This can beneficially allow the use of a smaller valve body  1560  within the inner frame  1520  while allowing the inner frame body  1522  to have a larger diameter proximate the connection between the inner frame body  1522  and the inner frame anchoring feature  1524 . This larger diameter can reduce the radial distance between the connection and the tip or end of the inner frame anchoring feature  1524 . This can beneficially enhance fatigue resistance of the inner frame anchoring feature  1524  by reducing the length of the cantilever. 
     While the illustrated inner frame body  1522  is bulbous, it is to be understood that the diameters of the upper region  1522   a , the intermediate region  1522   b , and/or the lower region  1522   c  can be the same such that the inner frame body  1522  is generally cylindrical along one or more regions. Moreover, while the illustrated embodiment includes a lower region  1522   a   having a greater diameter than the upper region  1522   c , it is to be understood that the diameters of the upper and lower regions  1522   a ,  1522   c  can be the same or the diameter of the upper region  1522   a  can be greater than the diameter of the lower region  1522   c . Moreover, although the inner frame body  1522  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  1522  can have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With reference next to the outer frame  1540  illustrated in  FIG.  33   , the outer frame  1540  can be attached to the inner frame  1520  using any of the fasteners and/or techniques described herein. Although the outer frame  1540  is illustrated as a separate component from the inner frame  1520 , it is to be understood that the frames  1520 ,  1540  can be unitarily or monolithically formed. 
     As shown in the illustrated embodiment, the outer frame  1540  can include an outer frame body  1542  and an outer frame anchoring feature  1544 . The outer frame body  1542  can have an upper region  1542   a , an intermediate region  1542   b , and a lower region  1542   c . When in an expanded configuration such as a fully expanded configuration, the outer frame body  1542  can have an enlarged shape with the intermediate region  1542   b  and the lower region  1542   c  being larger than the upper region  1542   a . The enlarged shape of the outer frame body  1542  can advantageously allow the outer frame body  1542  to engage a native valve annulus, native valve leaflets, or other tissue of the body cavity, while spacing the upper end from the heart or vessel wall. 
     The upper region  1542   a  of the outer frame body  1542  can include a first section  1546   a  and a second section  1546   b . The first section  1546   a  can be sized and/or shaped to generally match the size and/or shape of the inner frame  1520 . For example, the first section  1546   a  can have a curvature which matches a curvature of the upper region  1522   a  of the inner frame body  1522 . The second section  1546   b  can extend radially outwardly away from the inner frame  1520 . As shown in the illustrated embodiment, the transition between the first section  1546   a  and the second section  1546   b  can incorporate a bend such that the second section  1546   b  extends radially outwardly at a greater angle relative to the longitudinal axis. 
     The intermediate region  1542   b  of the outer frame body  1542  can extend generally downwardly from the outwardly-extending section  1546   b  of the upper region  1542   a . As shown, the intermediate region  1542   b  can have a generally constant diameter from an upper end to a lower end such that the intermediate region  1542   b  forms a generally cylindrical shape. The lower region  1542   c  of the outer frame body  1542  can extend generally downwardly from the lower end of the intermediate region  1542   b . As shown, the lower region  1542   c  of the outer frame body  1542  can have a generally constant diameter from an upper end to a lower end such that the lower region  1542   c  forms a generally cylindrical shape. As shown, the diameters of the intermediate region  1542   b  and the lower region  1542   c  are generally equivalent such that the intermediate region  1542   b  and the lower region  1542   c  together form a generally cylindrical shape. 
     While the intermediate and lower regions  1542   b ,  1542   c  have been described as cylindrical, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. For example, a diameter of the portion between the upper end and the lower end can be larger than the upper end and the lower end such that the intermediate region  1542   b  and/or lower region  1542   c  forms a generally bulbous shape. In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. Moreover, although the outer frame body  1542  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  1542  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  1540  illustrated in  FIG.  33   , the outer frame anchoring feature  1544  can extend outwardly relative to the longitudinal axis of the prosthesis  1500 . As shown in the illustrated embodiment, the outer frame anchoring feature  1544  is attached to the outer frame body  1542  along the upper region  1542   a . The outer frame anchoring feature  1544  can be attached to the outer frame body  1542  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end of the outer frame anchoring feature  1544  moves radially outwardly and upwardly. 
     In some embodiments, the outer frame anchoring feature  1544  can be attached to the outer frame body  1542  along a portion having a larger diameter, such as the intermediate region  1542   b  and/or the second section  1546   b . This can beneficially increase the radial extent of the outer frame anchoring feature  1544  while maintaining the same anchor length. Moreover, in some embodiments, the outer frame anchoring feature  1544  can be attached to the outer frame body  1542  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end of the outer frame anchoring feature  1544  moves radially outwardly and downwardly. This can beneficially facilitate alignment of the prosthesis  1500 . For example, in the event that a portion of the prosthesis  1500  is positioned too far into the ventricle, the outer frame anchoring features  1544  can contact tissue of the native mitral valve and exert a force to elevate at least that portion of the prosthesis  1500 . In some embodiments, the outer frame anchoring feature  1544  can include one or more individual anchors to allow the individual anchors to operate independently of other anchors. In some embodiments, the outer frame anchoring feature  1544  can be relatively flexible. For example, the outer frame anchoring feature  1544  can incorporate anchors having the serpentine shape of anchoring feature  2600  described in connection with  FIG.  50   . 
     The outer frame  1540 , such as the outer frame body  1542  can be used to attach or secure the prosthesis  1500  to a native valve, such as a native mitral valve. For example, the intermediate region  1542   b  of the outer frame body  1542  and/or the outer anchoring feature  1544  can be positioned to contact or engage a native valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. As another example, the outer frame body  1542  can be sized and positioned relative to the inner frame anchoring feature  1524  such that tissue of the body cavity positioned between the outer frame body  1542  and the inner frame anchoring feature  1524 , such as native valve leaflets and/or a native valve annulus, can be engaged or pinched to further secure the prosthesis  1500  to the tissue. 
     With continued reference to the prosthesis  1500  illustrated in  FIG.  33   , the valve body  1560  is attached to the inner frame  1520  within an interior of the inner frame body  1522 . The valve body  1560  functions as a one-way valve to allow blood flow in a first direction through the valve body  1560  and inhibit blood flow in a second direction through the valve body  1560 . 
     The valve body  1560  can include a plurality of valve leaflets  1562 , for example three leaflets  1562 , which are joined at commissures. The valve body  1560  can include one or more intermediate components  1564 . The intermediate components  1564  can be positioned between a portion of, or the entirety of, the leaflets  1562  and the inner frame  1520  such that at least a portion of the leaflets  1542  are coupled to the frame  1520  via the intermediate component  1564 . In this manner, a portion of, or the entirety of, the portion of the valve leaflets  1562  at the commissures and/or an arcuate edge of the valve leaflets  1562  are not directly coupled or attached to the inner frame  1520  and are indirectly coupled or “float” within the inner frame  1520 . For example, a portion of, or the entirety of, the portion of the valve leaflets  1562  proximate the commissures and/or the arcuate edge of the valve leaflets  1562  can be spaced radially inward from an inner surface of the inner frame  1520 . By using one or more intermediate components  1564 , the valve leaflets  1562  can be attached to non-cylindrical frames  1520  and/or frames  1520  having a diameter larger than that of the diameter of the valve leaflets  1562 . Further details on floating valve concepts can be found in U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entirety of which has been incorporated herein by reference. 
     With reference next to the outer skirt  1580  illustrated in  FIG.  33   , the outer skirt  1580  can be attached to the inner frame  1520  and/or outer frame  1540 . As shown, the outer skirt  1580  can be positioned around and secured to a portion of, or the entirety of, the exterior of the outer frame  1540 . The skirt  1580  can also be secured to a portion of the valve body  1560  such as, but not limited to, the intermediate components  1564 . For example, the skirt  1580  can be attached to an inflow region of the intermediate components  1564 . As shown, the outer skirt  1580  can follow the contours of the outer frame 1540; however, it is to be understood that at least a portion of the skirt  1580  can be spaced apart from at least a portion of both the inner frame  1520  and the outer frame  1540 . 
     With reference next to the inner skirt  1590  illustrated in  FIG.  33   , the inner skirt  1590  can be attached to the valve body  1560  and the outer skirt  1580 . As shown, a first end of the inner skirt  1590  can be coupled to the valve body  1560  along portions of the valve body  1560  which are proximate the inner frame  1520 . A second end of the inner skirt  1590  can be attached to the lower region of the outer skirt  1580 . In so doing, a smooth surface can be formed under each of the leaflets. This can beneficially enhance hemodynamics by allowing blood to more freely circulate and reducing areas of stagnation. In some embodiments, the inner skirt  1590  can beneficially reduce contact between the outer frame body  1542  and the inner frame body  1522 . 
     Although the prosthesis  1500  has been described as including an inner frame  1520 , an outer frame  1540 , a valve body  1560 , and skirts  1580 ,  1590 , it is to be understood that the prosthesis  1500  need not include all components. For example, in some embodiments, the prosthesis  1500  can include the inner frame  1520 , the outer frame  1540 , and the valve body  1560  while omitting the skirt  1580 . Moreover, although the components of the prosthesis  1500  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  1500  can be integrally or monolithically formed. For example, in some embodiments, the inner frame  1520  and the outer frame  1540  can be integrally or monolithically formed as a single component. 
     With reference next to  FIGS.  34 - 35   , an embodiment of a prosthesis  1600  in an expanded configuration is illustrated. The prosthesis  1600  can include an inner frame  1620 , an outer frame  1640 , a valve body  1660 , and one or more skirts, such as an outer skirt  1680  and an inner skirt  1690 . The prosthesis  1600  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein such as, but not limited to prostheses  100 ,  1500 . 
     With reference first to the outer frame  1640  illustrated in  FIGS.  34 - 35   , the outer frame  1640  can be attached to the inner frame  1620  using any of the fasteners and/or techniques described herein. Although the outer frame  1640  is illustrated as a separate component from the inner frame  1620 , it is to be understood that the frames  1620 ,  1640  can be unitarily or monolithically formed. 
     As shown in the illustrated embodiment, the outer frame  1640  can include an outer frame body  1642  and an outer frame anchoring feature  1644 . The outer frame body  1642  can have an upper region  1642   a , an intermediate region  1642   b , and a lower region  1642   c . At least a portion of the upper region  1642   a  of the outer frame body  1642  can be sized and/or shaped to generally match the size and/or shape of an upper region  1622   a  the inner frame  1620 . As shown in the illustrated embodiment, the upper region  1642   a  of the outer frame body  1642  can include one or more struts which generally match the size and/or shape of struts of the inner frame  1620 . This can locally reinforce a portion of the prosthesis  1600  by effectively increasing the wall thickness of the combined struts. Further details on reinforcing portions of the prosthesis can be found in U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entirety of which has been incorporated herein by reference. 
     When in an expanded configuration such as in a fully expanded configuration, the outer frame body  1642  can have a shape similar to that of outer frame body  1542  described above in connection with  FIG.  33   . As shown, the intermediate region  1642   b  and the lower region  1642   c  can have a diameter which is larger than the diameter of the upper region  1642   a . The upper region  1642   a  of the outer frame body  1642  can have a decreasing diameter from a lower end to an upper end such that the upper region  1642   a  is inclined or curved radially inwards towards the longitudinal axis of the prosthesis  1600 . Although the outer frame body  1642  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  1642  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  1600  illustrated in  FIG.  34   , the outer frame body  1642  can include a plurality of struts with at least some of the struts forming cells  1646   a - c . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper row of cells  1646   a  can have an irregular octagonal shape such as a “heart” shape. This larger shape can provide additional space for outer frame anchoring feature  1644 . This additional space can beneficially allow the outer frame  1640  to retain a smaller profile when crimped. The cell  1646   a  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper portion of cells  1646   a  can be formed from a set of circumferentially-expansible struts  1648   a  having a zig-zag or undulating shape forming a repeating “V” shape. The struts  1648   a  can extend radially outwardly from an upper end to a lower end. These struts can generally match the size and/or shape of struts of the inner frame  1620 . 
     The middle portion of cells  1646   a  can be formed from a set of struts  1648   b  extending downwardly from bottom ends of each of the “V” shapes. The struts  1648   b  can extend radially outwardly from an upper end to a lower end. The portion of the cells  1646   a  extending upwardly from the bottom end of struts  1648   b  may be considered to be a substantially non-foreshortening portion of the outer frame  1640 . 
     The lower portion of cells  1646   a  can be formed from a set of circumferentially-expansible struts  1648   c  having a zig-zag or undulating shape forming a repeating “V” shape. As shown in the illustrated embodiment, the struts  1648   c  can incorporate a curvature such that the lower end of struts  1648   c  extend more parallel with the longitudinal axis than the upper end of the struts  1648   c . One or more of the upper ends or tips of the circumferentially-expansible struts  1648   c   can be a “free” apex which is not connected to a strut. For example, as shown in the illustrated embodiment, every other upper end or tip of circumferentially-expansible struts  1648   b  is a free apex. However, it is to be understood that other configurations can be used. For example, every upper apex along the upper end can be connected to a strut. 
     The middle and/or lower rows of cells  1646   b - c  can have a different shape from the cells  1646   a  of the first row. The middle row of cells  1646   b  and the lower row of cells  1646   c  can have a diamond or generally diamond shape. The diamond or generally diamond shape can be formed via a combination of struts. 
     The upper portion of cells  1646   b  can be formed from the set of circumferentially-expansible struts  1648   c  such that cells  1646   b  share struts with cells  1646   a . The lower portion of cells  1646   b  can be formed from a set of circumferentially-expansible struts  1648   d . As shown in the illustrated embodiment, one or more of the circumferentially-expansible struts  1648   d  can extend generally in a downward direction generally parallel to the longitudinal axis of the outer frame  1640 . 
     The upper portion of cells  1646   c  can be formed from the set of circumferentially-expansible struts  1648   d  such that cells  1646   c  share struts with cells  1646   b . The lower portion of cells  1646   c  can be formed from a set of circumferentially-expansible struts  1648   e . Circumferentially-expansible struts  1648   e  can extend generally in a downward direction. 
     As shown in the illustrated embodiment, there can be a row of nine cells  1646   a  and a row of eighteen cells  1646   b - c . While each of the cells  1646   a - c  are shown as having the same shape as other cells  1646   a - c  of the same row, it is to be understood that the shapes of cells  1646   a - c  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. 
     With continued reference to  FIGS.  34 - 35   , the outer frame  1640  can include an outer frame anchoring feature  1644 . The outer frame anchoring feature  1644  can include one or more individual anchors  1644   a  having tips or ends  1644   b . As shown, the outer frame anchoring feature  1644  includes nine anchors; however, it is to be understood that a fewer or greater number of anchors can be used. For example, the outer frame anchoring feature  1644  can include three anchors  1644   a . 
     As shown, the anchors  1644   a  extend from an upper portion of cells  1646   a , such as an upper apex of cells  1646   a . The anchors  1644   a  can extend downwardly. The anchors  1644   a   can be attached to the outer frame body  1642  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end  1644   b  of the anchors  1644   a  moves radially outwardly and upwardly. 
     In some embodiments, one or more anchors  1644   a  can be attached to the outer frame body  1642  along struts  1648   c . For example, the anchors  1644   a  can extend from one or more of the free apices. The anchors  1644   a  can be attached to the outer frame body  1642  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end  1644   b  of the anchors  1644   a  moves radially outwardly and downwardly. This can beneficially facilitate alignment of the prosthesis  1600 . 
     As shown in the illustrated embodiment, the outer frame  1600  can include a set of eyelets  1650 . The upper set of eyelets  1650  can extend from an upper region  1642   a  of the outer frame body  1642 . As shown, the upper set of eyelets  1650  can extend from an upper portion of cells  1646   a , such as the upper apices of cells  1646   a . The upper set of eyelets  1650  can be used to attach the outer frame  1640  to the inner frame  1620 . For example, in some embodiments, the inner frame  1620  can include one or more eyelets which correspond to the eyelets  2150 . In such embodiments, the inner frame  1620  and outer frame  1640  can be attached together via eyelets  1650  and corresponding eyelets on the inner frame  1620 . For example, the inner frame  1620  and outer frame  1640  can be sutured together through said eyelets or attached via other means, such as mechanical fasteners (e.g., screws, rivets, and the like). 
     As shown, the set of eyelets  1650  can include two eyelets extending in series from each “V” shaped strut. This can reduce the likelihood that the outer frame  1640  twists along an axis of the eyelet. However, it is to be understood that some “V” shaped struts may not include an eyelet. Moreover, it is to be understood that a fewer or greater number of eyelets can extend from a “V” shaped strut. 
     The outer frame  1640  can include a set of locking tabs  1652  extending from at or proximate an upper end of the upper region  1642   a . As shown, the locking tabs  1652  can extend upwardly from the set of eyelets  1650 . The outer frame  1640  can include twelve locking tabs  1652 , however, it is to be understood that a greater number or lesser number of locking tabs can be used. The locking tabs  1652  can include a longitudinally-extending strut  1652   a . At an upper end of the strut  1652   a , the locking tab  1652  can include an enlarged head  1652   b . As shown, the enlarged head  1652   b  can have a semi-circular or semi-elliptical shape forming a “mushroom” shape with the strut  1652   a . The locking tab  1652  can include an eyelet  1652   c  which can be positioned through the enlarged head  1652   b . It is to be understood that the locking tab  1652  can include an eyelet at other locations, or can include more than a single eyelet. 
     The locking tab  1652  can be advantageously used with multiple types of delivery systems. For example, the shape of the struts  1652   a  and the enlarged head  1652   b  can be used to secure the outer frame  1640  to a “slot” based delivery system. The eyelets  1652   c  and/or eyelets  1650  can be used to secure the outer frame  1640  to a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery of the outer frame  1640  and the prosthesis  1600 . This can advantageously facilitate recapture and repositioning of the outer frame  1640  and the prosthesis  1600  in situ. In some embodiments, the prosthesis  1600  can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which are hereby incorporated by reference and made a part of this specification. 
     The outer frame  1640 , such as the outer frame body  1642  can be used to attach or secure the prosthesis  1600  to a native valve, such as a native mitral valve. For example, the intermediate region  1642   b  of the outer frame body  1642  and/or the outer anchoring feature  1644  can be positioned to contact or engage a native valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. As another example, the outer frame body  1642  can be sized and positioned relative to the inner frame anchoring feature  1624  such that tissue of the body cavity positioned between the outer frame body  1642  and the inner frame anchoring feature  1624 , such as native valve leaflets and/or a native valve annulus, can be engaged or pinched to further secure the prosthesis  1600  to the tissue. As shown, the inner frame anchoring feature  1624  includes nine anchors; however, it is to be understood that a fewer or greater number of anchors can be used. In some embodiments, the number of individual anchors can be chosen as a multiple of the number of commissures for the valve body  1660 . For example, for a valve body  1660  have three commissures, the inner frame anchoring feature  1624  can have three individual anchors (1:1 ratio), six individual anchors (2:1 ratio), nine individual anchors (3:1 ratio), twelve individual anchors (4:1 ratio), fifteen individual anchors (5:1 ratio), or any other multiple of three. In some embodiments, the number of individual anchors does not correspond to the number of commissures of the valve body  1660 . 
     With continued reference to the prosthesis  1600  illustrated in  FIGS.  34 - 35   , the valve body  1660  is attached to the inner frame  1620  within an interior of the inner frame body  1622 . The valve body  1660  functions as a one-way valve to allow blood flow in a first direction through the valve body  1660  and inhibit blood flow in a second direction through the valve body  1660 . 
     The valve body  1660  can include a plurality of valve leaflets  1662 , for example three leaflets  1662 , which are joined at commissures. The valve body  1660  can include one or more intermediate components  1664 . The intermediate components  1664  can be positioned between a portion of, or the entirety of, the leaflets  1662  and the inner frame  1620  such that at least a portion of the leaflets  1642  are coupled to the frame  1620  via the intermediate component  1664 . In this manner, a portion of, or the entirety of, the portion of the valve leaflets  1662  at the commissures and/or an arcuate edge of the valve leaflets  1662  are not directly coupled or attached to the inner frame  1620  and are indirectly coupled or “float” within the inner frame  1620 . Further details on floating valve concepts can be found in U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entirety of which is incorporated herein by reference. 
     With reference next to the outer skirt  1680  illustrated in  FIG.  34   , the outer skirt  1680  can be attached to the inner frame  1620  and/or outer frame  1640 . As shown, the outer skirt  1680  can be positioned around and secured to a portion of, or the entirety of, the exterior of the outer frame  1640 . The inner skirt  1690  can be attached to the valve body  1660  and the outer skirt  1680 . As shown, a first end of the inner skirt  1690  can be coupled to the valve body  1660  along portions of the valve body  1660  which are proximate the inner frame  1620 . A second end of the inner skirt  1690  can be attached to the lower region of the outer skirt  1680 . In so doing, a smooth surface can be formed along under each of the leaflets. This can beneficially enhance hemodynamics by allowing blood to more freely circulate and reducing areas of stagnation. 
     Although the prosthesis  1600  has been described as including an inner frame  1620 , an outer frame  1640 , a valve body  1660 , and skirts  1680 ,  1690 , it is to be understood that the prosthesis  1600  need not include all components. For example, in some embodiments, the prosthesis  1600  can include the inner frame  1620 , the outer frame  1640 , and the valve body  1660  while omitting the skirt  1680 . Moreover, although the components of the prosthesis  1600  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  1600  can be integrally or monolithically formed. For example, in some embodiments, the inner frame  1620  and the outer frame  1640  can be integrally or monolithically formed as a single component. 
     With reference next to  FIG.  36   , an embodiment of an inner frame  1700  in an expanded configuration is illustrated. The inner frame  1700  can include an inner frame body  1702 , an inner frame anchoring feature  1704  and/or a set of locking tabs  1712 . The locking tabs  1812  can include features similar to other locking tabs described herein. As shown in the illustrated embodiment, the tips or ends of the inner frame anchoring feature  1704  can incorporate two or more prongs which extend in different directions. This can beneficially increase a tissue contact surface for the tips or ends particularly when used with a cover or cushion. 
     The inner frame body  1702  can have an upper region  1702   a , an intermediate region  1702   b , and a lower region  1702   c . The inner frame body  1702  can have a shape similar to that described above in connection with inner frame bodies  1520  and  1620 . As shown, the inner frame body  1702  can have a generally bulbous shape such that the diameters of the upper region  1702   a  and the lower region  1702   c  are less than the diameter of the intermediate region  1702   b . The diameter of the upper region  1702   a  can be less than the diameter of the lower region  1702   c . 
     While the illustrated inner frame body  1702  is bulbous, it is to be understood that the diameters of the upper region  1702   a , the intermediate region  1702   b , and/or the lower region  1702   c  can be the same such that the inner frame body  1702  is generally cylindrical along one or more regions. Moreover, while the illustrated embodiment includes a lower region  1702   a  having a greater diameter than the upper region  1702   c , it is to be understood that the diameters of the lower and upper regions  1702   a ,  1702   c  can be the same or the diameter of the upper region  1702   a  can be greater than the diameter of the lower region  1702   c . Moreover, although the inner frame body  1702  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  1702  can have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     The inner frame body  1702  can include a plurality of struts with at least some of the struts forming cells  1706   a - c . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper row of cells  1706   a  can have an elongated hexagonal shape. The cell  1706   a  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper portion of cells  1706   a  can be formed from a set of circumferentially-expansible struts  1708   a  having a zig-zag or undulating shape forming a repeating “V” shape. The struts  1708   a  can extend radially outwardly from an upper end to a lower end. 
     The middle portion of cells  1706   a  can be formed from a set of eyelets  1710  extending downwardly from bottom ends of each of the “V” shapes. The eyelets  1710  can extend radially outwardly from an upper end to a lower end. The eyelets  1710  can be used to attach various components to the inner frame  1700 . In some embodiments, the eyelets  1710  can be used to attach the inner frame  1700  to an outer frame. For example, the outer frame may be similar to outer frame  1640  having eyelets  1650 . Such an attachment location can be lower than that illustrated in connection with prosthesis  1600 . This can allow the use of a more axially compact outer frame. In some embodiments, the eyelets  1710  can be utilized to attach a valve body to the inner frame  1700 . 
     The portion of the cells  1706   a  extending upwardly from the bottom end of eyelets  1710  may be considered to be a substantially non-foreshortening portion of the inner frame  1700 . Although eyelets  1710  are used, it is to be understood that a strut can be utilized in lieu of or in combination with eyelets  1710 . 
     The lower portion of cells  1706   a  can be formed from a set of circumferentially-expansible struts  1708   b  having a zig-zag or undulating shape forming a repeating “V” shape. As shown in the illustrated embodiment, the struts  1708   b  can incorporate a curvature such that the lower end of struts  1708   b  extend more parallel with the longitudinal axis than the upper end of the struts  1708   b . 
     The middle and/or lower rows of cells  1706   b - c  can have a different shape from the cells  1706   a  of the first row. The middle row of cells  1706   b  and the lower row of cells  1706   c  can have a diamond or generally diamond shape. The diamond or generally diamond shape can be formed via a combination of struts. 
     The upper portion of cells  1706   b  can be formed from the set of circumferentially-expansible struts  1708   b  such that cells  1706   b  share struts with cells  1706   a . The lower portion of cells  1706   b  can be formed from a set of circumferentially-expansible struts  1708   c . As shown in the illustrated embodiment, one or more of the circumferentially-expansible struts  1708   c  can extend generally in a downward direction generally parallel to the longitudinal axis of the outer frame  1640 . 
     The upper portion of cells  1706   c  can be formed from the set of circumferentially-expansible struts  1708   c  such that cells  1706   c  share struts with cells  1706   b . The lower portion of cells  1706   c  can be formed from a set of circumferentially-expansible struts  1708   d . Circumferentially-expansible struts  1708   d  can extend generally in a downward direction and/or radially inward direction.. 
     As shown in the illustrated embodiment, there can be nine cells in each row of cells  1706   a - c . While each of the cells  1706   a - c  are shown as having the same shape as other cells  1706   a - c  of the same row, it is to be understood that the shapes of cells  1706   a - c  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. 
     With reference next to  FIG.  37   , an embodiment of an outer frame  1800  in an expanded configuration is illustrated. The outer frame  1800  can include an outer frame body  1802  and/or locking tabs  1812 . The locking tabs  1812  can include features similar to other locking tabs described herein. 
     When in an expanded configuration such as in a fully expanded configuration, the outer frame body  1802  can have a shape similar to that of outer frames  1540  and  1640  described above in connection with  FIGS.  33  and  34 - 35   . As shown, the intermediate region  1802   b  and the lower region  1802   c  can have a diameter which is larger than the diameter of the upper region  1802   a . The upper region  1802   a  of the outer frame body  1802  can increase in diameter from an upper end to a lower end such that the upper region  1802   a  is inclined or curved radially outwards away from the longitudinal axis of the outer frame  1800 . Although the outer frame body  1802  has been illustrated as having a circular cross-sections, it is to be understood that all or a portion of the outer frame body  1802  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     The outer frame body  1802  can include a plurality of struts with at least some of the struts forming cells  1804   a - b . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper region  1802   a  can include an elongate strut  1806   a . The elongate strut  1806   a  can extend radially outwardly from the longitudinal axis of the outer frame  1802 . The elongate strut  1806   a  can incorporate a bend  1808  to orient an upper portion of the strut  1806   a  in a direction more parallel with the longitudinal axis. The use of an elongate strut  1806   a  can reduce the change in axial length when the outer frame  1800  transitions from a collapsed configuration to an expanded configuration. 
     In some embodiments, the elongate strut  1806   a  can beneficially dampen radial displacements and/or forces experienced by other portions of the outer frame body  1800 . For example, the elongate strut  1806   a  can dampen radial displacements and/or forces due to compression of the intermediate and/or lower regions  1802   b ,  1802   c  during phases of the cardiac cycle. In situations where the outer frame  1800  is positioned within a native mitral valve, these compressive forces can be cyclically imparted by the native mitral valve annulus during phases of the cardiac cycle. Dampening of such displacements and/or forces by the elongate strut  1806   a  can reduce forces applied on an inner frame which may cause undesirable movement and/or deformation of the inner frame. The amount of dampening can be chosen by adjusting the width, length, taper, materials, and other characteristics of the elongate strut  1806   a . 
     The upper row of cells  1804   a  can have a diamond or generally diamond shape. As shown in the illustrated embodiment, the upper portion of cells  1804   a  can be formed from a set of circumferentially-expansible struts  1806   b  having a zig-zag or undulating shape forming a repeating “V” shape. One or more of the upper ends or tips of the circumferentially-expansible struts  1806   b  can be a “free” apex which is not connected to a strut. For example, as shown in the illustrated embodiment, every other upper end or tip of circumferentially-expansible struts  1806   b  is a free apex. However, it is to be understood that other configurations can be used. For example, every upper apex along the upper end can be connected to a strut. The lower portion of cells  1804   a  can be formed from a set of circumferentially-expansible struts  1806   c  having a zig-zag or undulating shape forming a repeating “V” shape. Although the outer frame  1800  is shown without an anchoring feature, it is to be understood that an anchoring feature may be incorporated into the outer frame  1800  in a manner similar to those described in connection with other outer frames described herein. For example, an anchoring feature may extend from one or more of the free apices of the circumferentially-expansible struts  1806   b . 
     The upper portion of cells  1804   b  can be formed from the set of circumferentially-expansible struts  1806   c  such that cells  1804   b  share struts with cells  1804   a . The lower portion of cells  1804   b  can be formed from a set of circumferentially-expansible struts  1806   d . 
     As shown in the illustrated embodiment, there can be a row of eighteen cells  1804   a - b . While each of the cells  1804   a - b  are shown as having the same shape as other cells  1804   a - b  of the same row, it is to be understood that the shapes of cells  1804   a - b  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. 
     As shown in the illustrated embodiment, the outer frame  1800  can include a set of eyelets  1810 . The eyelets  1810  can extend from an upper region  1802   a  of the outer frame body  1802 . As shown, the eyelets  1810  can extend from an upper end of struts  1806   a . In some embodiments, the eyelets  1810  can be used to attach the outer frame  1800  to an inner frame. For example, the inner frame may be similar to inner frame  1620  and/or  1700  having eyelets  1710 . This can allow the use of a more axially compact outer frame. In some embodiments, the eyelets  1710  can be utilized to attach a valve body to the inner frame  1700 . In some embodiments, the upper set of eyelets  1810  can be used to attach the outer frame  1800  to a delivery system. For example, sutures or tethers of a delivery system can be attached or passed through the eyelets  1810 . 
     With reference next to  FIG.  38 A , an embodiment of a prosthesis  1900  in an expanded configuration is illustrated. The prosthesis  1900  can include an inner frame  1920 , an outer frame  1940 , a valve body  1960 , and one or more skirts, such as outer skirt  1980  and inner skirt  1990 . The prosthesis  1900  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein. 
     With reference first to the inner frame  1920 , the inner frame  1920  can include an inner frame body  1922  and an inner frame anchoring feature  1924 . The inner frame body  1922  can have an upper region  1922   a , an intermediate region  1922   b , and a lower region  1922   c . As shown, the inner frame body  1922  can have a generally cylindrical shape. The inner frame body  1922  can include a bend  1926  along a lower region  1922   c  of the inner frame body  1920  such that a region  1928  of the inner frame body  1920  tapers radially inwardly towards the longitudinal axis of the prosthesis  1900 . The shape of region  1928  can match the shape of a portion of the outer frame  1940 . 
     While the illustrated inner frame body  1922  is generally cylindrical, it is to be understood that the diameters of the upper region  1922   a , the intermediate region  1922   b , and/or the lower region  1922   c  can be different. For example, in some embodiments, a diameter of the intermediate region  1922   a  can be larger than the upper region  1922   b  and the lower region  1922   c  such that the frame body  1922  has a generally bulbous shape. Moreover, although the inner frame body  1922  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  1922  can have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With reference next to the outer frame  1940  illustrated in  FIG.  38 A , the outer frame  1940  can be attached to the inner frame  1920  using any of the fasteners and/or techniques described herein. Although the outer frame  1940  is illustrated as a separate component from the inner frame  1920 , it is to be understood that the frames  1920 ,  1940  can be unitarily or monolithically formed. 
     As shown in the illustrated embodiment, the outer frame  1940  can include an outer frame body  1942  and an outer frame anchoring feature  1944 . The outer frame body  1942  can have an upper region  1942   a , an intermediate region  1942   b , and a lower region  1942   c . When in an expanded configuration such as a fully expanded configuration, the outer frame body  1942  can have an enlarged shape with the upper region  1942   a  and the intermediate region  1942   b  being larger than the lower region  1942   c . The enlarged shape of the outer frame body  1942  can advantageously allow the outer frame body  1942  to engage a native valve annulus, native valve leaflets, or other tissue of the body cavity, while spacing the upper end from the heart or vessel wall. 
     As shown in the illustrated embodiment, the lower region  1942   c  of the outer frame body  1942  can be attached to the lower region  1922   c  of the inner frame body  1922 . This can provide significant advantages particularly with respect to the geometry of the prosthesis  1900  when the prosthesis  1900  is in a crimped or collapsed configuration. For example, in embodiments where the outer frame body  1942  is capable of foreshortening, any increase in the axial length of the outer frame body  1942  as the outer frame body  1942  is crimped occurs upwardly relative to the lower regions  1922   c ,  1942   c  from which the frame bodies are attached. In this manner, regardless of the axial length of the outer frame body  1942  in the crimped or collapsed configuration, the outer frame body  1942  can be prevented from extending over the inner frame anchoring features  1922  when crimped or collapsed. 
     The lower region  1942   c  of the outer frame body  1942  can include a region  1946 . The region  1946  can extend radially inwardly towards the longitudinal axis of the prosthesis  1900 . As shown in the illustrated embodiment, a portion of region  1946  can be sized and/or shaped to generally match the size and/or shape of the region  1928  of inner frame  1920 . This can advantageously enhance securement of the outer frame  1940  to the inner frame  1920  by providing a greater area over which the outer frame  1940  can be attached to the inner frame  1920 . Moreover, by bending the region  1928  of inner frame  1920  to match the shape of region  1946  of the outer frame  1940 , the fatigue resistance of the outer frame  1940  can be enhanced as the lower end of outer frame  1940  need not be significantly bent to match the geometry of the inner frame  1920 . 
     The intermediate region  1942   b  of the outer frame body  1942  can extend generally upwardly from the lower region  1942   c . As shown, the intermediate region  1942   b  can have a generally constant diameter from an upper end to a lower end such that the intermediate region  1942   b  forms a generally cylindrical shape. The upper region  1942   a  of the outer frame body  1942  can extend generally upwardly from the lower end of the intermediate region  1942   b . As shown, the upper region  1942   a  of the outer frame body  1942  can have a generally constant diameter from an upper end to a lower end such that the upper region  1942   a  forms a generally cylindrical shape. While, the diameters of the intermediate region and the upper region  1942   a  are generally equivalent such that the intermediate region and the upper region  1942   b ,  1942   a  together form a generally cylindrical shape, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween can be different. 
     For example, a diameter of the portion between the upper end and the lower end can be larger than the upper end and the lower end such that the intermediate region and/or lower region  1942   b ,  1942   a  forms a generally bulbous shape. In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. 
     As another example, the diameter of the upper end of the upper region  1942   a  can be greater than the diameter of the lower end of the upper region  1942   a  such that the upper region  1942   a  extends radially outwardly away from the longitudinal axis of the prosthesis  1900 . This can advantageously enhance securement and/or stability when the prosthesis  1900  is positioned within a native valve, such as the native mitral valve. For example, when the prosthesis  1900  is positioned within a native mitral valve, the upper region  1942   a  can extend radially outwardly over an atrial side of the native mitral valve annulus. This can inhibit movement of the prosthesis  1900  into the left ventricle during phases of the cardiac cycle (e.g., diastole). In some embodiments, the upper end can increase to a diameter which is similar to, or greater than, a diameter formed around the tips or ends  1924   b  of inner frame anchoring feature  1924 . In some embodiments, the upper region  1942   a  can extend generally perpendicularly to the intermediate region  1942   b  to form a flange. 
     Moreover, although the outer frame body  1942  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  1942  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  1940  illustrated in  FIG.  38 A , the outer frame anchoring feature  1944  can extend outwardly relative to the longitudinal axis of the prosthesis  1900 . As shown in the illustrated embodiment, the outer frame anchoring feature  1944  is attached to the outer frame body  1942  along the upper region  1942   a . The outer frame anchoring feature  1944  can be attached to the outer frame body  1942  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end of the outer frame anchoring feature  1944  moves radially outwardly and downwardly; however, it is to be understood that the outer frame anchoring feature  1944  can be attached to the outer frame body  1942  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end of the outer frame anchoring feature  1944  moves radially outwardly and upwardly. The radial extent of the outer frame anchor feature  1944  can be generally the same as the radial extend of the inner frame anchoring feature  1924 . Although the anchoring feature  1944  is shown attached to the outer frame body  1942 , it is to be understood that the anchoring feature  1944  can be attached to the inner frame body  1922 . Moreover, it is to be understood that the anchoring feature  1944  can be one or more barbs or penetrating structures. The barbs may be angled upwardly, angled downwardly, and/or perpendicular. Although shown extending along an upper region of the outer frame body  1942 , it is to be understood that such barbs or other penetrating structures may extend along other regions of the outer frame body  1942 . 
     Similar to other prostheses described herein, components of the outer frame  1940 , can be used to attach or secure the prosthesis  1900  to a native valve, such as a native mitral valve. For example, the intermediate region  1942   b  of the outer frame body  1942  and/or the outer anchoring feature  1944  can be positioned to contact or engage a native valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. As another example, the outer frame body  1942  can be sized and positioned relative to the inner frame anchoring feature  1924  such that tissue of the body cavity positioned between the outer frame body  1942  and the inner frame anchoring feature  1924 , such as native valve leaflets and/or a native valve annulus, can be engaged or pinched to further secure the prosthesis  1900  to the tissue. As shown in the illustrated embodiment, the profile of the outer frame  1940  can generally match the profile of the inner frame anchoring feature  1924 . This can beneficially enhance sealing along the outer frame  1940  when tissue, such as a leaflet, is captured between the outer frame  1940  and the inner frame anchoring feature  1924 . This can also beneficially enhance sealing along the outer frame  1940  even if tissue, such as a leaflet, is not captured between the outer frame  1940  and the inner frame anchoring feature. 
     The shape of the illustrated outer frame body  1942  can enhance securement of the prosthesis  1900 . For example, as shown in  FIG.  38 B , in some instances where the prosthesis  1900  is positioned within the native mitral valve, the outer frame  1940  can compress in a manner such that the region above the annulus  40  bends further radially inwardly than a region below the annulus  40 . This can allow the outer frame  1940  to impart a force on the native leaflets and/or native mitral valve annulus  40  in at least a direction towards the atrium. This application of force can result in a counter-force which can tend to push the outer frame  1940 , and the prosthesis  1900 , towards the ventricle. In embodiments where the inner frame anchoring feature  1924  contacts the annulus  40 , this can reduce the systolic loads applied to the inner frame anchoring feature  1924  during systole. This can beneficially reduce and distribute fatigue loads on the inner frame anchoring feature  1924 . Moreover, this counter-force can reduce the likelihood that the prosthesis  1900  shifts towards the atrium during systole. 
     However, it is to be understood that the outer frame  1900  can take on other shapes. For example, in some instances where the prosthesis  1900  is positioned within the native mitral valve, the outer frame  1940  can compress in a manner such that the region below the annulus  40  bends further radially inwardly than a region above the annulus  40 . This can allow the outer frame  1940  to impart a force on the native leaflets and/or native mitral valve annulus  40  in at least a direction towards the ventricle. This application of force can result in a counter-force which can tend to push the outer frame  1940 , and the prosthesis  1900 , towards the atrium. In embodiments where the inner frame anchoring feature  1924  contacts the annulus, this can increase the force applied by the inner frame anchoring feature  1924  to the annulus. Moreover, this counter-force can reduce the likelihood that the prosthesis  1900  shifts towards the left ventricle during stages of the cardiac cycle. 
     The shape of the illustrated outer frame body  1942  can facilitate positioning of the inner frame anchoring feature  1924  during partial deployment of the prosthesis  1900 . During this stage of deployment, the inner frame anchoring feature  1924  can be released while the upper end of the outer frame body  1942  is retained within the delivery system. Since the larger diameter portion of the outer frame body  1942  is proximate the upper region  1942   a  of the outer frame body  1942  and the lower region  1942   c  is attached to the inner frame  1920 , the outer frame body  1942  can be substantially constrained from expanding. In this manner, the outer frame body  1942  can be maintained in a smaller profile during partial deployment. The smaller profile of the outer frame body  1942  can increase the gap between the inner frame anchoring feature  1924  and the outer frame body  1942  during partial deployment which can facilitate placement of the inner frame anchoring feature  1924  at a target tissue location and/or capture of native valve tissue between the inner frame anchoring feature  1924  and the outer frame body  1942 . 
     With continued reference to the prosthesis  1900  illustrated in  FIG.  38 A , the valve body  1960  is attached to the inner frame  1920  within an interior of the inner frame body  1922 . The valve body  1960  functions as a one-way valve to allow blood flow in a first direction through the valve body  1960  and inhibit blood flow in a second direction through the valve body  1960 . As shown in the illustrated embodiment, the valve body  1960  can include a plurality of leaflets  1962  and/or a liner  1964 . The liner  1964  can be positioned between at least the upper edges of the leaflets  1962  to an inflow end of the inner frame  1960 . In some instances, the leaflets  1962  can be attached to the liner  1964  which is attached to the inner frame  1960 . 
     With reference next to the skirts  1980 ,  1990  illustrated in  FIG.  38 A , the outer skirt  1980  can be attached to the inner frame  1920  and/or outer frame  1940 . As shown, the outer skirt  1980  can be positioned around and secured to a portion of, or the entirety of, the exterior of the outer frame  1940 . As shown, the outer skirt  1980  can follow the contours of the outer frame  1940 ; however, it is to be understood that at least a portion of the skirt  1980  can be spaced apart from at least a portion of both the inner frame  1920  and the outer frame  1940 . The inner skirt  1990  can be attached to the valve body  1960  and the outer skirt  1980 . As shown, a first end of the inner skirt  1990  can be coupled to the valve body  1960  along portions of the valve body  1960  which are proximate the inner frame  1920 . A second end of the inner skirt  1990  can be attached to the lower region of the outer skirt  1980 . Although described as separate structures, it is to be understood that the outer skirt  1980  and the inner skirt  1990  can be monolithically formed. Moreover, it is to be understood that the liner  1964  and the inner skirt  1990  can be monolithically formed. 
     The outer skirt  1980  can extend to a location below the connection between the inner frame body  1922  and the inner frame anchoring feature  1924 . This can advantageously provide a greater surface area upon which the outer skirt  1980  can form a seal with tissue of the native valve, such as the native mitral valve. Moreover, the inward taper of the outer skirt  1980  can better conform to the native anatomy, such as the native mitral valve leaflets, when parts of the native anatomy are positioned between the inner frame anchoring feature  1924  and the outer frame  1940 . This can further enhance sealing along the outer skirt  1980 . 
     Although the outer skirt  1980  is shown extending along an exterior of the outer frame body  1942 , it is to be understood that the outer skirt  1980  can extend along an interior of the outer frame body  1942 . This can allow the outer frame body  1942  to directly contact tissue of the body cavity. In embodiments where the outer frame body  1942  includes struts and/or cells, the tissue can extend between the struts and/or cells. This can beneficially enhance securement of the prosthesis  1900  to the body cavity. 
     As shown in the illustrated embodiment, a cavity  1992  can be formed between the outer skirt  1980  and the inner skirt  1990  which opens upwardly. In instances where the prosthesis  1900  is positioned within the native mitral valve, the cavity  1992  can open towards the atrium. Accordingly, during systole, the cavity  1992  can be at a lower pressure than the ventricle. This can beneficially enhance sealing outer skirt  1980  since the native tissue, such as the native mitral valve leaflets, are forced towards the outer skirt  1980  due to a pressure differential between the ventricle and the cavity  1992 . 
     In some embodiments, the cavity  1992  can be filed with material such as, but not limited to, silicone, saline, foam, hydrogel, knit polyesters such as polyethylene terephthalate (PET) and/or polyvalerolactone (PVL), other materials, and/or a combination of such materials. The filler material can be included in the cavity  1992  prior to the prosthesis  1900  being deployed. In some embodiments, the filler material can be added after the prosthesis  1900  has been at least partially deployed. For example, the filler material can be pre-formed into a cylindrical shape or ring can subsequently positioned within the cavity  1992  after the prosthesis  1900  has been deployed. 
     The filler material can be used to fill the cavity  1992  to reduce the open volume. In some embodiments, the filler material can promote tissue growth within the cavity. In some embodiments, the filler material can promote healing of tissue surrounding the prosthesis  1900 . In some embodiments, the filler material can beneficially alter the structural characteristics of the outer frame  1940  and/or inner frame  1920 . For example, the filler material can be used to reduce the compliancy of the outer frame  1940  along certain portions of the outer frame and/or to transmit forces applied to the outer frame  1940  to the inner frame  1920 . This can beneficially allow the outer frame  2040  to exert a greater force along these regions. 
     In some embodiments, the cavity  1992  can include a cover (not shown) to partially or fully close the cavity  1992 . An upper end of the outer skirt  1980  can be attached to the upper end of the inner skirt  1990  and/or liner  1964  such that the cover extends generally perpendicular to the longitudinal axis. However, it is to be understood that the cover can take other shapes. In some embodiments, the cover can extend downwardly and radially inwardly to funnel blood towards the inflow end of the inner frame  1920 . In some embodiments, the cover can extend upwardly and radially inwardly. This can form a tapered shape which can facilitate recapture of the device. 
     In some embodiments, the cover can be at least partially permeable to allow the flow of blood into the cavity  1992  and/or sufficiently impermeable to inhibit larger particulates such as clots. For example, the cover can be formed from a mesh such as a cloth or wire mesh, a woven material, and/or a perforated material. This can facilitate the growth of tissue within the cavity  1992  and/or on the cover. For example, the cover can allow for endothelialization. This tissue growth can be enhanced in combination with the filler material noted above. In some embodiments, the cover can be formed from a substantially impermeable material to inhibit the flow of fluids into the cavity  1992 . In some embodiments, this material can be the same material forming the skirt  2080  and/or the inner skirt  1990 . 
     Although the prosthesis  1900  has been described as including an inner frame  1920 , an outer frame  1940 , a valve body  1960 , and skirts  1980 ,  1990 , it is to be understood that the prosthesis  1900  need not include all components. For example, in some embodiments, the prosthesis  1900  can include the inner frame  1920 , the outer frame  1940 , the valve body  1960 , and the outer skirt  1980  while omitting the inner skirt  1990 , particularly in instances where a cover is used. Moreover, although the components of the prosthesis  1900  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  1900  can be integrally or monolithically formed. For example, in some embodiments, the inner frame  1920  and the outer frame  1940  can be integrally or monolithically formed as a single component. 
     With reference next to  FIGS.  39 - 42   , an embodiment of a prosthesis  2000  in an expanded configuration, or components of the prosthesis  2000 , are illustrated. The prosthesis  2000  can include an inner frame  2020 , an outer frame  2040 , a valve body  2060 , and a skirt  2080 . The prosthesis  1900  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein such as prosthesis  1900 . 
     With reference first to the outer frame  2040  illustrated in  FIGS.  39 - 41   , the outer frame  2040  can include an outer frame body  2042 . The outer frame body  2042  can have an upper region  2042   a , an intermediate region  2042   b , and a lower region  2042   c . As shown, when in an expanded configuration such as the fully expanded configuration, the outer frame body  2042  can have an enlarged shape with an upper region  2042   a  and an intermediate region  2042   b  being larger than the lower region  2042   c . The enlarged shape of the outer frame body  2040  can advantageously allow the outer frame body to engage a native valve annulus, native valve leaflets, or other body cavity, while spacing the inlet and outlet from the heart or vessel wall. 
     The lower region  2042   c  of the outer frame body  2042  can extend radially outwardly away from the longitudinal axis of the prosthesis  2000  and/or in an upward direction towards the upper region. As shown in the illustrated embodiment, the lower region  2042   c  can incorporate a bend or curve such that the angle of the lower region  2042   c  relative to the longitudinal axis decreases towards an upper end of the lower region  2042   c . However, it is to be understood that in some embodiments, the lower region  2042   c  can extend substantially linearly. 
     The intermediate region  2042   b  of the outer frame body  2042  can extend generally upwardly from the lower region  2042   c . As shown, the intermediate region  2042   b  can have a generally constant diameter from a lower end to an upper end such that the intermediate region  2042   b  forms a generally cylindrical shape. The upper region  2042   a  of the outer frame body  2042  can extend generally upwardly from the upper end of the intermediate region  2042   b . As shown, the upper region  2042   a  of the outer frame body  2042  can have a generally constant diameter from a lower end to an upper end such that the upper region  2042   a  forms a generally cylindrical shape. However, it is to be understood that the diameters of the upper end, the lower end, and/or the portion therebetween of the intermediate region and/or upper region  2042   b ,  2042   a  can be different. For example, in some embodiments, a diameter of the portion between the upper and lower ends can be larger than diameters of the upper and lower ends such that the intermediate region and/or upper region  2042   b ,  2042   a  form a generally bulbous shape (as shown, for example, in connection with frame  300  illustrated in  FIGS.  7 - 8   ). In some embodiments, the diameter of the lower end can be larger than the diameter of the upper end. In other embodiments, the diameter of the upper end can be larger than the diameter of the lower end. 
     Moreover, although the outer frame body  2042  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the outer frame body  2042  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  2040  illustrated in  FIGS.  39 - 41   , the outer frame body  2042  can include a plurality of struts with at least some of the struts forming cells  2044   a - d . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     As shown in the illustrated embodiment, the cells  2044   a - d  can have a diamond or generally diamond shape. The cells  2044   a - d  can be considered to be a substantially foreshortening portion of the outer frame  2040 . While the struts forming cells  2044   a - d  are generally illustrated as being straight segments, it is to be understood that some or all of the struts may not form entirely straight segments. For example, the struts can include some curvature such that the upper and/or lower apices are curved. 
     As shown in the illustrated embodiment, there can be three rows of eighteen cells 2044a-c and a row of nine cells  2044   d . While each of the cells  2044   a - d  are shown as having the same shape as other cells  2044   a - d  of the same row, it is to be understood that the shapes of cells  2044   a - d  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. 
     With reference next to  FIG.  42   , the inner frame  2020  of prosthesis  2000  is illustrated. The inner frame  2020  can include an inner frame body  2022  and an inner frame anchoring feature  2024 . As shown, the inner frame body  2022  can have an upper region  2022   a , an intermediate region  2022   b , and a lower region  2022   c . As shown, the inner frame body  2022  can have a generally cylindrical shape such that the diameters of the upper region  2022   a , the intermediate region  2022   b , and the lower region  2022   c  are generally equivalent. However, it is to be understood that the diameters of the upper region  2022   a , the intermediate region  2022   b , and/or the lower region  2022   c  can be different. For example, in some embodiments, a diameter of the lower region  2022   c  can be larger than the upper region  2022   a . In other embodiments, the diameter of the upper region  2022   a  can be larger than the diameter of the lower region  2022   c . 
     The diameter of the upper region  2022   a , intermediate region  2022   b , and/or lower region  2022   c  of the inner frame body  2022  may be chosen such that the inner frame body  2022  is adequately spaced from the body cavity when the prosthesis  2000  is positioned within the body cavity. For example, in embodiments where the prosthesis  2000  is positioned within the native mitral valve, the inner frame body  2022  may have a diameter which is less than the diameter of the native mitral valve annulus. Although the inner frame body  2022  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the inner frame body  2022  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     The inner frame body  2022  can be substantially non-foreshortening. This can advantageously allow the inner frame body  2022  to retain its axial length when the inner frame body  2022  transitions from a collapsed configuration to an expanded configuration. This can reduce the crimp length of the inner frame body  2022  which can facilitate positioning within a delivery system. As shown in the illustrated embodiment, the inner frame body  2022  can include longitudinally-extending struts  2026 . The longitudinally-extending struts  2026  can extend in a direction generally parallel to the longitudinal axis of the prosthesis  2000 . The longitudinally-extending struts  2026  can extend from an upper region  2022   a  of the inner frame body  2022  to a lower region  2022   c  of the inner frame body  2022 . Although the longitudinally-extending struts  2026  extend in a direction generally parallel to the longitudinal axis of the prosthesis  2000 , it is to be understood that at least a portion of these struts  2026  can extend in a direction transverse to the longitudinal axis. 
     As shown in the illustrate embodiment, the inner frame body  2022  can include nine longitudinally-extending struts  2026 . It is to be understood that a fewer or greater number of struts can be used. The number of struts can be a multiple of the number of commissures of the valve body. For example, in instances where a valve body having three commissures is used, the inner frame body  2022  can include three, six, twelve, fifteen, or more struts. 
     A plurality of undulating struts can extend between the longitudinally-extending struts  2026 . In some embodiments, the inner frame body  2022  can include one or more sets of struts which extend circumferentially around the inner frame body  2022 . As shown, the inner frame body  2022  can include a first, second, and third set of struts  2028   a - c  extending circumferentially around the inner frame body  2022 . Each of the sets of struts  2028   a - c  can have a zig-zag or undulating shape forming a repeating “V” shape. The tips of these “V” shapes can form a “U” shape. This can facilitate transitioning of the inner frame body  2022  between a collapsed configuration and an expanded configuration. 
     As shown, the first and second sets of struts  2028   a - b  can extend in a direction generally parallel to the longitudinal axis of the prosthesis  2000 . As such, the first and second sets of struts  2028   a - b  can form a generally cylindrical shape. The third set of struts  2028   c  can extend radially inwardly towards the longitudinal axis of the prosthesis  2000 . This radially inward shape can correspond to the shape of the lower region  2042   c  of the outer frame body  2042 . This can advantageously facilitate attachment of the outer frame body  2042  to the inner frame body  2022  along the lower regions  2022   c ,  2042   c . 
     The inner frame  2020  can include one or more eyelets to facilitate attachment of one or more components of the prosthesis  2000  to the inner frame  2020 . As shown in the illustrated embodiment, the inner frame  2020  can include an upper and/or lower set of eyelets  2030   a - b . The upper set of eyelets  2030   a  can be positioned along the upper region  2022   a  of the inner frame body  2022 . As shown, the eyelets  2030   a  can be positioned at or proximate an upper end of the longitudinally-extending struts  2026 . 
     The eyelets  2030   a  can be used to attach the inner frame  2020  to a delivery instrument, such as a suture or tether-based delivery instrument. For example, sutures or tethers can be attached to the eyelets  2030   a . In some embodiments, the outer frame  2040  can include an upper set of eyelets (not shown) in lieu of, or in combination with, the upper eyelets  2030   a . In embodiments with eyelets on both the inner frame  2020  and the outer frame  2040 , a tether or suture can be passed through corresponding eyelets of the inner frame  2020  and the outer frame  2040 . This tether or suture can draw the inner frame  2020  and the outer frame  2040  closer together when tightened. This can facilitate recapture of the prosthesis  2000 . 
     The lower set of eyelets  2030   b  can be positioned along the lower region  2022   c  of the inner frame body  2022 . As shown in the illustrated embodiment, the lower set of eyelets  2030   b  can be positioned along the lower row of struts  2028   c . The eyelets  2030   b  can be utilized to facilitate securement of the outer frame  2040  to the inner frame  2020 . For example, in some embodiments, the outer frame  2040  can include one or more eyelets which correspond to the eyelets  2030   b . The inner frame  2020  and outer frame  2040  can be attached together via eyelets  2030   b  and corresponding eyelets on the outer frame  2040 . For example, the inner frame  2020  and outer frame  2040  can be sutured together through said eyelets or attached via other means, such as mechanical fasteners (e.g., screws, rivets, and the like). 
     Although a single eyelet  2030   b  is shown extending from each “V” shaped strut, it is to be understood that some “V” shaped struts may not include an eyelet. Moreover, it is to be understood that multiple eyelets can extend from a “V” shaped strut. For example, two eyelets can extend in series. This can enhance the stability of the coupling between the inner frame  2020  and the outer frame  2040  by allowing a suture to pass through two adjacent eyelets. For example, this can reduce the likelihood that the outer frame  2040  twists along an axis of the eyelet. 
     With continued reference to the inner frame  2020  illustrated in  FIG.  42   , the inner frame anchoring feature  2024  can extend at or proximate a lower end of the lower region  2022   c  of the inner frame body  2022 . The inner frame anchoring feature  2024  can be formed from a plurality of individual anchors  2024   a  extending from the frame body  2022 . The anchors  2024   a  can extend downwardly from one or more attachment points to the inner frame body  2022  including, but not limited to, longitudinally-extending struts  2026 . As shown, the anchors  2024   a  can be an extension of the longitudinally-extending struts  2026 . This can beneficially enhance the structural integrity of the anchors  2024   a . The anchors  2024   a  can bend to extend generally radially outwardly of the longitudinal axis of the prosthesis  2000 . Although the anchors  2024   a  are shown extending from longitudinally-extending struts  2026 , it is to be understood that the anchors  2024   a   can be connected to the inner frame body  2022  frame at one of many different locations including apices, junctions, other parts of struts, etc. 
     The anchors  2024   a  can extend upwardly towards an end or tip  2024   b . The ends or tips  2024   b  can be positioned radially outwardly relative to the longitudinal axis of the prosthesis  2000 . As shown, the ends or tips  2024   b  can extend upwardly in a direction generally parallel to the longitudinal axis of the prosthesis  2000 ; however, it is to be understood that the ends or tips  2024   b  can have other geometries as described herein. For example, the ends or tips can extend generally perpendicular to the longitudinal axis of the prosthesis  2000 . Although the anchors  2024   a  are shown with a single bend, it is to be understood that one or more anchors can comprise first, second, third, or more spaced apart bending stages along the length of each anchor. Further details that may be incorporated and/or interchanged with the features described herein are disclosed in U.S. Publication Nos. 2014/0277422, 2014/0277427, 2014/0277390, and 2015/0328000, and U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, which have been incorporated by reference herein. 
     As shown in the illustrated embodiment, the inner frame anchoring feature  2024  can include nine individual anchors; however, it is to be understood that a greater number or lesser number of individual anchors can be used. For example, the number of individual anchors can be chosen as a multiple of the number of commissures for the valve body  2060 . As such, for a prosthesis  2000  with a valve body  2060  having three commissures, the inner frame anchoring feature  2024  can have three individual anchors (1:1 ratio), six individual anchors (2:1 ratio), nine individual anchors (3:1 ratio), twelve individual anchors (4:1 ratio), fifteen individual anchors (5:1 ratio), or any other multiple of three. It is to be understood that the number of individual anchors need not correspond to the number of commissures of the valve body  2060 . 
     With reference back to  FIGS.  39 - 41   , the inner frame anchoring feature  2024  can include covers and/or cushions  2032  to surround or partially surround at least a portion of the inner frame anchoring feature  2024 , such as the tips or ends  2024   b . The covers and/or cushions  2032  can be similar to cushions  238  and/or those described in U.S. Publication No. 2015/0328000, which has been incorporated by reference in its entirety. As shown in the illustrated embodiment, covers and/or cushions  2032  are attached to all anchors 2024a; however, it is to be understood that the covers and/or cushions  2032  can be utilized on a subset of anchors  2024   a . 
     As shown in the illustrated embodiment, the radial extent of the tips or ends  2024   b  of the inner frame anchoring feature  2024  can be greater than the radial extent of the outer frame body  2042  at the plane of the tips or ends  2024   b . The tips or ends  2024   b  can be positioned such that the tips or ends  2024   b  are spaced apart from an exterior of the outer frame body  2042 . This can provide a gap in which tissue of the body cavity can be retained. For example, in instances where the prosthesis  2000  is positioned within a native mitral valve, the native mitral valve leaflets can be positioned between these gaps. It is to be understood that this gap between the tips or ends  2024   b  and the outer frame body  2042  can be reduced. For example, in some embodiments, the tips or ends  2024   b  can be positioned proximate, or contact, the exterior of the outer frame body  2042 . This can beneficially increase the force applied by the prosthesis  2000  to pinch or grasp tissue of the body cavity therebetween. 
     With continued reference to  FIGS.  39 - 41   , the valve body  2060  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other valve bodies described herein. The valve body  2060  can include one or more leaflets  2062  and/or a liner  2064 . The liner  2064  can be used to assist with fluid flow through and/or around the prosthesis  2000 , such as through and around the inner frame  2020  and the valve leaflets  2062 . The liner  2062  can surround at least a portion of the valve leaflets  2062  and be connected to one or more of the valve leaflets  2062 . For example, as shown in the illustrated embodiment, the one or more valve leaflets  2062  can be attached to the liner  2064  along an upper edge of the valve leaflets  2062 . 
     As shown in the illustrated embodiment, the liner  2064  can be positioned within the interior of the inner frame  2020  and can form an inner wall of the prosthesis  2000 . It is also contemplated that the liner  2064  can at least be partially positioned along an exterior of the inner frame  2020  and/or outer frame  2040  such that at least a portion of the liner  2064  is radially outward, relative to the longitudinal axis of the prosthesis  2000 , from struts of the inner frame  2020  and/or outer frame  2040 . As shown in the illustrated embodiment, the liner  2064  can be positioned along an upper or inlet side of the inner frame  2020 . The liner  2064  can extend above the upper edge of the valve leaflets  2062  towards the upper end of the inner frame  2020 . As shown, the liner  2064  can also extend below the upper edge of the valve leaflet  2062  towards the lower end of the inner frame  2020 . 
     With continued reference to  FIGS.  39 - 41   , the skirt  2080  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other skirts described herein. The skirt  2080  can be positioned around and secured to at least a portion of the exterior of the prosthesis  2000  such as, but not limited to, the inner frame  2020  and/or the outer frame  2040 . The skirt  2080  can be annular and can extend entirely circumferentially around the prosthesis  2000 . The skirt  2080  can prevent or inhibit backflow of fluids around the prosthesis  2000 . For example, with the skirt  2080  positioned annularly around an exterior of the prosthesis  2000 , the skirt  2080  can create an axial barrier to fluid flow exterior to the prosthesis  2000  when deployed within a body cavity. As shown, the skirt  2080  can seal against at least a portion of tissue surrounding the body cavity. In addition, the skirt  2080  can encourage tissue in-growth between the flap assembly  2080  and natural tissue of the body cavity. This may further help to prevent leakage of blood flow around the prosthesis  2000 . 
     As shown in the illustrated embodiment, the skirt  2080  can extend along an exterior of the outer frame body  2042 . This can increase the contact area between tissue of the body cavity and the skirt  2080 . This can beneficially enhance sealing around the prosthesis  2000  by providing smooth, continuous contact along the periphery of the outer frame  2040  and the skirt  2080 . In embodiments where the skirt  2080  is formed from a material which encourages tissue in-growth, this increased contact area can be beneficial. 
     While the skirt  2080  is shown extending along the exterior of the outer frame body  2042 , it is to be understood that portions of, or the entirety of, the skirt  2080  can extend along an interior of the outer frame. This can allow tissue of the body cavity to contact and/or extend between struts forming the outer frame body  2042 . For example, tissue of the body cavity can contact and/or extend between struts forming one or more of cells  2044   a - d . This can beneficially enhance stability and/or securement of the prosthesis  2000  to tissue of the body cavity. It is also to be understood that while the skirt  2080  is shown tautly attached to the outer frame  2040 , a portion of, or the entirety of, the skirt  2080  can be loosely attached such that a portion of, or the entirety of, the skirt  2080  is movable relative to the outer frame  2040 . 
     The upper end of the skirt  2080  can be positioned at or proximate an upper end of the outer frame body  2042  and/or an upper end of the inner frame body  2022 . The lower end of the skirt  2080  can be positioned at or proximate a lower end of the outer frame body  2042 . The skirt  2080  may be attached to the outer frame  2040  and/or inner frame  2020  using any fasteners and/or techniques described herein. For example, portions of the skirt  2080  can be attached to struts and/or anchoring features of the outer frame  2040  and/or inner frame  2020  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. 
     With reference back to the inner frame  2020  illustrated in  FIG.  42   , the inner frame  2020  can include a set of locking tabs  2034  extending at or proximate an upper end of the upper region  2022   a  of the inner frame body  2022 . As shown, the locking tabs  2034  can extend at or proximate an upper end of the longitudinal struts  2030  and/or the upper set of eyelets  2030   a . The locking tabs  2034  can extend upwardly in a direction generally aligned with the longitudinal axis of the prosthesis  2000 . As shown in the illustrated embodiment, the locking tabs  2034  can include a longitudinally-extending strut  2034   a . At an upper end of the strut  2034   a , the locking tab  2034  can include an enlarged head  2034   b . As shown, the enlarged head  2034   b  can have a semi-circular or semi-elliptical shape forming a “mushroom” shape with the strut  2034   a . As shown, the inner frame  2020  can include nine locking tabs  2034 ; however, it is to be understood that a greater number or lesser number of locking tabs can be used. Moreover, it is to be understood that portions of, or the entirety of, the locking tabs  2034  can be omitted. 
     The locking tabs  2034  can be advantageously used with multiple types of delivery systems. For example, the shape of the locking tabs  2034  can allow the prosthesis  2000  to be used with multiple delivery systems such as, but not limited to, a “slot” based delivery system and a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery. In some embodiments, the prosthesis  2000  can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which are hereby incorporated by reference and made a part of this specification. 
     Although the locking tabs  2034  are shown extending from the inner frame  2020 , it is to be understood that locking tabs can extend from the outer frame  2040  in lieu of, or in addition to, the locking tabs  2034 . Moreover, although the locking tabs are shown extending generally parallel to the longitudinal axis, it is to be understood that locking tabs, such as locking tabs  2034  or those on the outer frame, can extend at an angle relative to the longitudinal axis. This can beneficially allow the locking tabs to function as an upper set of anchors (similar to upper anchors  1944  discussed in connection with  FIG.  38 A ). 
     With reference next to  FIG.  43   , an embodiment of an outer frame  2100  in an expanded configuration is illustrated. The outer frame  2100  can include an outer frame body  2102  and/or an outer frame anchoring feature  2104 . The outer frame  2100  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other outer frames described herein such as outer frames  1940  and  2040  described above in connection with  FIGS.  38  and  39 - 41   . 
     When in an expanded configuration such as in a fully expanded configuration, the outer frame body  2102  can have a shape similar to that of outer frame  1940  and  2040 . As shown, the upper region  2102   a  and the intermediate region  2102   b  can have a diameter which is larger than the diameter of the lower region  2102   c . The lower region  2102   c  of the outer frame body  2102  can have a decreasing diameter from an upper end of the lower region  2102   c  to a lower end of the lower region  2102   c  such that the lower region  2102   c  is inclined or curved radially inwards towards the longitudinal axis of the outer frame  2100 . This radially inward incline or curve of the lower region  2102   c  can facilitate capture of native valve leaflets between the outer frame  2100  and other portions, such as an anchoring feature, of the prosthesis in which the outer frame  2100  is used. Moreover, this radially inward inclined or curve of the lower region  2102   c  can reduce or inhibit potential trauma to tissue of the body cavity, such as the native leaflets and/or native valve annulus. For example, the curvature and/or inclination of the lower region  2102   c  can be chosen to better conform to the curvature of tissue positioned between the outer frame  2100  and an anchoring feature of another portion of a prosthesis in which the outer frame  2100  is used. 
     Although the outer frame body  2102  has been illustrated as having circular cross-sections, it is to be understood that all or a portion of the outer frame body  2102  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     With continued reference to the outer frame  2100  illustrated in  FIG.  43   , the outer frame body  2102  can include a plurality of struts with at least some of the struts forming cells  2106   a - c . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper row of cells  2106   a  can have an irregular octagonal shape such as a “heart” shape. This larger shape can provide additional space for outer frame anchoring feature  2104 . This additional space can beneficially allow the outer frame  2100  to retain a smaller profile when crimped. The cell  2106   a  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper portion of cells  2106   a  can be formed from a set of circumferentially-expansible struts  2108   a  having a zig-zag or undulating shape forming a repeating “V” shape. 
     The middle portion of cells  2106   a  can be formed from a set of struts  2108   b  extending downwardly from bottom ends of each of the “V” shapes. The struts  2108   b  can extend along with a plane parallel to and/or extending through the longitudinal axis of the prosthesis  2100 . The portion of the cells  2106   a  extending upwardly from the bottom end of struts  2108   b  may be considered to be a substantially non-foreshortening portion of the outer frame  2100 . 
     The lower portion of cells  2106   a  can be formed from a set of circumferentially-expansible struts  2108   c  having a zig-zag or undulating shape forming a repeating “V” shape. One or more of the upper ends or tips of the circumferentially-expansible struts  2108   c  can be a “free” apex which is not connected to a strut. For example, as shown in the illustrated embodiment, every other upper end or tip of circumferentially-expansible struts  2108   b  is a free apex. However, it is to be understood that other configurations can be used. For example, every upper apex along the upper end can be connected to a strut. 
     The middle and/or lower rows of cells  2106   b - c  can have a different shape from the cells  2106   a  of the first row. The middle row of cells  2106   b  and the lower row of cells  2106   c  can have a diamond or generally diamond shape. The diamond or generally diamond shape can be formed via a combination of struts. 
     The upper portion of cells  2106   b  can be formed from the set of circumferentially-expansible struts  2108   c  such that cells  2106   b  share struts with cells  2106   a . The lower portion of cells  2106   b  can be formed from a set of circumferentially-expansible struts  2108   d . As shown in the illustrated embodiment, one or more of the circumferentially-expansible struts  2108   d  can extend generally in a downward direction and extend radially inwardly towards the longitudinal axis of the outer frame  2100 . For example, the one or more circumferentially-expansible struts  2108   d  can be curved such that an upper portion of the struts  2108   d  is positioned further from the longitudinal axis of the outer frame  2100  than the lower portion of the struts  2108   d . 
     The upper portion of cells  2106   c  can be formed from the set of circumferentially-expansible struts  2108   d  such that cells  2106   c  share struts with cells  2106   b . The lower portion of cells  2106   c  can be formed from a set of circumferentially-expansible struts  2108   e . Circumferentially-expansible struts  2108   e  can extend generally in a downward direction. As shown in the illustrated embodiment, the circumferentially-expansible struts  2108   e  can be inclined or curved towards the longitudinal axis of the outer frame  2100  such that an upper portion of the struts  2108   e  is positioned further from the longitudinal axis of the outer frame  2100  than the lower portion of the struts  2108   e . In some embodiments, the circumferentially-expansible struts  2108   d  can extend in a direction generally parallel to the longitudinal axis of the outer frame  2100 . 
     As shown in the illustrated embodiment, there can be a row of nine cells  2106   a , a row of eighteen cells  2106   b , and a row of nine cells  2106   c . While each of the cells  2106   a - c  are shown as having the same shape as other cells  2106   a - c  of the same row, it is to be understood that the shapes of cells  2106   a - c  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. 
     With continued reference to  FIG.  43   , the outer frame  2100  can include an outer frame anchoring feature  2104 . The outer frame anchoring feature  2104  can include one or more individual anchors  2104   a  having tips or ends  2104   b . As shown, the outer frame anchoring feature  2104  includes three anchors; however, it is to be understood that a fewer or greater number of anchors can be used. For example, the outer frame anchoring feature  2104  can include nine anchors  2104   a . 
     As shown, the anchors  2104   a  extend from an upper portion of cells  2106   a , such as an upper apex of cells  2106   a . The anchors  2104   a  can extend downwardly. The anchors  2104   a  can be attached to the outer frame body  2102  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end  2104   b  of the anchors  2104   a  moves radially outwardly and upwardly. 
     In some embodiments, one or more anchors  2104   a  can be attached to the outer frame body  2102  along struts  2108   c . For example, the anchors  2104   a  can extend from one or more of the free apices. The anchors  2104   a  can be attached to the outer frame body  2102  such that, when transitioning from a collapsed configuration to an expanded configuration, the tip or end  2104   b  of the anchors  2104   a  moves radially outwardly and downwardly. This can beneficially facilitate alignment of the prosthesis  2104   a . Moreover, it is to be understood that the anchors  2104   a  and/or the tips or ends  2104   b  can be barbs or penetrating structures. The barbs may be angled upwardly, angled downwardly, and/or perpendicular. Although shown extending along an upper region of the outer frame body  2102 , it is to be understood that such barbs or other penetrating structures may extend along other regions of the outer frame body  2102 . 
     As shown in the illustrated embodiment, the outer frame  2100  can include an upper set of eyelets  2110   a  and/or a lower set of eyelets  2110   b . The upper set of eyelets  2110   a  can extend from an upper region  2102   a  of the outer frame body  2102 . As shown, the upper set of eyelets  2110   a  can extend from an upper portion of cells  2106   a , such as the upper apices of cells  2106   a . The upper set of eyelets  2110   a  can be used to attach the outer frame  2100  to a delivery system. For example, sutures or tethers of a delivery system can be attached or passed through the upper set of eyelets  2110   a . 
     The lower set of eyelets  2110   b  can be positioned along the lower region  2102   c  of the outer frame body  2102 . As shown, the lower set of eyelets  2110   b  can extend from an upper portion of cells  2106   c , such as the lower apices of cells  2106   c . The lower set of eyelets  2110   b  can be used to attach the outer frame  2100  to an inner frame of a prosthesis. For example, in some embodiments, the inner frame can include one or more eyelets which correspond to the eyelets  2110   b . The inner frame and outer frame  2100  can be attached together via these eyelets. For example, the inner frame and outer frame  2040  can be sutured together through said eyelets or attached via other means, such as mechanical fasteners (e.g., screws, rivets, and the like). 
     As shown, the lower set of eyelets  2110   b  can include two eyelets extending in series from each “V” shaped strut. This can reduce the likelihood that the outer frame  2040  twists along an axis of the eyelet. However, it is to be understood that some “V” shaped struts may not include an eyelet. Moreover, it is to be understood that a fewer or greater number of eyelets can extend from a “V” shaped strut. 
     With reference next to  FIG.  44   , an embodiment of a prosthesis  2200  in an expanded configuration, or components of the prosthesis  2200 , are illustrated. The prosthesis  2200  can include an inner frame  2220 , an outer frame  2240 , a valve body  2260 , and a skirt  2280 . The prosthesis  2200  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of prostheses described herein such as prosthesis  1900  and  2000 . 
     The prosthesis  2200  can include a cover  2290  to close the gap between the upper regions of the inner frame  2220  and the outer frame  2240 . The cover  2290  can extend between the upper end of the outer skirt  2280  and the upper end of the leaflets  2262  and/or liner  2264  of the valve body  2260 . As shown, the cover  2290  extends generally perpendicular to the longitudinal axis; however, it is to be understood that the cover  2290  can be transverse to the longitudinal axis. In some embodiments, the cover  2290  can extend downwardly and radially inwardly to funnel blood towards the inflow end of the inner frame  2220  and towards the leaflets. In some embodiments, the cover  2290  can extend upwardly and radially inwardly. This can form a tapered shape which can facilitate recapture of the device. As shown, the cover  2290  can be integrally formed with the skirt 2280; however, it is to be understood that the cover  2290  can be formed separately from the shirt  2280 . 
     The prosthesis  2200  can include a cushion  2224  extending along the length of the inner frame anchoring feature  2222 . The cushion  2224  can include a first section  2224   a  extending along a portion of an individual anchor and a second section  2224   b  extending along a tip or end of an individual anchor. The cushion  2224  can beneficially reduce trauma to tissue of the body cavity. 
     With reference next to  FIG.  45   , an embodiment of a prosthesis  2300  in an expanded configuration, or components of the prosthesis  2300 , are illustrated. The prosthesis  2300  can include an inner frame  2320 , an outer frame  2340 , a valve body  2360 , and a skirt  2380 . The prosthesis  2300  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of prostheses described herein. 
     The prosthesis  2300  can include sutures  2390  extending between the inner frame  2320  and the outer frame  2340 . In some embodiments, the sutures  2390  can extend between the lower portion of the outer frame  2340  and the lower portion of the inner frame body  2322  and/or inner frame anchoring feature  2324 . The sutures  2390  can be tensioned such that a radially inward force is applied on the outer frame  2340  and a radially outward force is applied on the inner frame  2320 . This can beneficially enhance the structural integrity of the prosthesis  2300  by maintaining the outer frame  2340  and inner frame  2320  with an initial amount of strain. In embodiments utilizing materials with a generally linear modulus of elasticity, the pre-strained frame components can require a greater degree of force to further strain the frame components. 
     Moreover, the structural integrity of the prosthesis  2300  can be enhanced by tying movement of the outer frame  2340  and the inner frame  2320  together. For example, application of a downwardly-oriented force on anchoring feature  2342  can tend to move the inner frame anchoring feature  2342  in a downward and/or radially inward direction. By tying the outer frame  2340  and the inner frame  2320  together, the inner frame  2320  can pull the outer frame  2340  in the same direction. As such, the forces required to move the inner frame anchoring feature  2342  would be higher than if the inner frame anchoring feature  2342  moved independently of the outer frame  2340 . 
     With reference next to  FIGS.  46 - 47   , an embodiment of a prosthesis  2400  in an expanded configuration is illustrated. The prosthesis  2400  can include an inner frame  2420 , an outer frame  2440 , a valve body  2460 , and one or more skirts, such as outer skirt  2480  and inner skirt  2490 . The prosthesis  2400  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein such as prostheses  1900 ,  2000 , and  2200 . 
     With reference first to the inner frame  2420 , the inner frame  2420  can include an inner frame body  2422  and an inner frame anchoring feature  2424 . As shown, the inner frame body  2422  can have a generally bulbous shape and/or frustoconical shape. The diameter of the upper region  2422   a  can be less than the diameter of the lower region  2422   c . This can beneficially allow the use of a smaller valve body  2460  within the inner frame  2420  while allowing the inner frame body  2422  to have a larger diameter proximate the connection between the inner frame body  2422  and the inner frame anchoring feature  2424 . This larger diameter can reduce the radial distance between the connection and the tip or end of the inner frame anchoring feature  2424 . This can beneficially enhance fatigue resistance of the inner frame anchoring feature  2424  by reducing the length of the cantilever. Moreover, this can allow the inner frame anchoring feature  2424  to more closely match the geometry of the outer frame  2440 . The larger diameter can also facilitate valve-in-valve functionality by providing a larger diameter portion in which a subsequent replacement valve may be received. 
     As shown in the illustrated embodiment, the intermediate region  2422   b  can have a frustoconical shape such that the diameter increases linearly from an upper end to a lower end of the intermediate region  2422   b . However, it is to be understood that the intermediate region  2422   b  can incorporate a curvature. For example, the intermediate region  2422   b  can include a geometry similar to that of inner frame body  1522   b  described in connection with  FIG.  33   . The inner frame body  2422  can include a bend  2426  along a lower region  2422   c  of the inner frame body  2420  such that a region  2428  of the inner frame body  2420  tapers radially inwardly towards the longitudinal axis of the prosthesis  2400 . The shape of region  2428  can match the shape of a portion of the outer frame  2440 . 
     The radially inward bend can enhance the durability of the valve body  2460 . As shown in  FIG.  47   , an intermediate component  2464  of the valve body  2460  can couple a commissure formed by leaflets  2464  to the inner frame body  2422 . The intermediate component  2464  can extend from below the leaflets  2464 . As such, when the valve body  2460  closes due to a flow of fluid in the upward direction, the intermediate component  2464  is pulled upwardly into tension as opposed to shear. This can be beneficial in instances where the intermediate component  2464  is more resistant to tension than shear as it can reduce the likelihood of the intermediate component  2464  tearing. 
     With continued reference to the prosthesis  2400  illustrated in  FIG.  46   , the valve body  2460  is attached to the inner frame  2420  within an interior of the inner frame body  2422 . The valve body  2460  functions as a one-way valve to allow blood flow in a first direction through the valve body  2460  and inhibit blood flow in a second direction through the valve body  2460 . 
     The valve body  2460  can include a plurality of valve leaflets  2462 , for example three leaflets  2462 , which are joined at commissures. The valve body  2460  can include one or more intermediate components  2464 . The intermediate components  2464  can be positioned between a portion of, or the entirety of, the leaflets  2462  and the inner frame  2420  such that at least a portion of the leaflets  2462  are coupled to the frame  2420  via the intermediate component  2464 . In this manner, a portion of, or the entirety of, the portion of the valve leaflets  2462  at the commissures and/or an arcuate edge of the valve leaflets  2462  are not directly coupled or attached to the inner frame  2420  and are indirectly coupled or “float” within the inner frame  2420 . For example, a portion of, or the entirety of, the portion of the valve leaflets  2462  proximate the commissures and/or the arcuate edge of the valve leaflets  2462  can be spaced radially inward from an inner surface of the inner frame  2420 . By using one or more intermediate components  2464 , the valve leaflets  2462  can be attached to non-cylindrical frames  2420  and/or frames  2420  having a diameter larger than that of the diameter of the valve leaflets  2462 . Further details on floating valve concepts can be found in U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entirety of which is incorporated herein by reference. 
     With reference next to the skirts  2480 ,  2490  illustrated in  FIG.  46   , the outer skirt  2480  can be attached to the inner frame  2420  and/or outer frame  2440 . As shown, the outer skirt  2480  can be positioned around and secured to a portion of, or the entirety of, the exterior of the outer frame  2440 . As shown, the outer skirt  2480  can follow the contours of the outer frame  2440 ; however, it is to be understood that at least a portion of the skirt  2480  can be spaced apart from at least a portion of both the inner frame  2420  and the outer frame  2440 . 
     The inner skirt  2490  can be attached to the valve body  2460  and the outer skirt  2480 . As shown, a first end of the inner skirt  2490  can be coupled to the valve body  2460  along portions of the valve body  2460  which are proximate the inner frame  2420 . A second end of the inner skirt  2490  can be attached to the lower region of the outer skirt  2480 . As shown, the inner skirt  2490  can be positioned radially outwardly of the inner frame  2420 . The inner skirt  2490  can be detached from the inner frame  2490  along portions between the upper end and the lower end such that the inner skirt  2490 . This can allow the inner skirt  2490  to form a shape which facilitate fluid flow around the underside of the valve body  2460 . This can improve washout on the underside of the valve thereby beneficially reducing the risk of thrombosis or clot formation under and around the valve body  2460 . 
     Although the inner skirt  2490  is shown positioned radially outwardly from the inner frame  2420 , it is to be understood that the inner skirt  2490  can follow the contours of the inner frame  2420  and/or be positioned along an interior surface of the inner skirt  2490 . In some embodiments, the inner frame  2490  can incorporate the shape of the illustrated inner skirt  2490 . 
     Although the prosthesis  2400  has been described as including an inner frame  2420 , an outer frame  2440 , a valve body  2460 , and skirts  2480 ,  2490 , it is to be understood that the prosthesis  2400  need not include all components. For example, in some embodiments, the prosthesis  2400  can include the inner frame  2420 , the outer frame  2440 , and the valve body  2460  while omitting the skirt  2480 . Moreover, although the components of the prosthesis  2400  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  2400  can be integrally or monolithically formed. For example, in some embodiments, the inner frame  2420  and the outer frame  2440  can be integrally or monolithically formed as a single component. 
     With reference next to  FIGS.  11 A-K , embodiments of prostheses 500a-k in expanded configurations are illustrated. The prostheses 500a-k can include inner frames  520   a - k  and outer frames  540   a - k . The inner frames  520   a - k  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of the inner frames described herein such as inner frames  120 ,  220 ,  400 . The outer frames  540   a - k  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of the outer frames described herein such as outer frames  140 ,  240 ,  300 . 
     With reference first to the prosthesis  500   a  illustrated in  FIG.  11 A , outer frame  540   a  can include an upper region  542   a , an intermediate region  544   a , and a lower region  546   a . The upper region  542   a  can include a longitudinally-extending section  548   a  and an outwardly-extending section  550   a . The intermediate region  544   a  can extend from the outwardly-extending section  550   a . As shown in the illustrated embodiment, the intermediate region  544   a  can extend in a direction generally parallel to a longitudinal axis of the prosthesis  500   a . The lower region  546   a  can extend from the intermediate region  544   a . The lower region  546   a  can bend to extend radially inward towards the longitudinal axis of the prosthesis  500   a . In some embodiments, the lower region  546   a  can extend in a direction more perpendicular to the longitudinal axis of the prosthesis  500   a  than parallel. For example, the lower region  546   a  can extend in a direction generally perpendicular to the longitudinal axis of the prosthesis  500   a . 
     Portions of the outer frame  540   a , such as the upper region  542   a , can be attached to the inner frame  520   a  at or proximate an upper region  522   a  of the inner frame  520   a . As shown in the illustrated embodiment, the outer frame  540   a  can be sized such that a lower end of the outer frame  540   a  is at or proximate an upper end or tip  526   a  of anchoring feature  524   a . 
     With reference next to the prosthesis  500   b  illustrated in  FIG.  11 B , outer frame  540   b  can include an upper region  542   b , an intermediate region  544   b , and a lower region  546   b . The upper region  542   b  can include a longitudinally-extending section  548   b  and an outwardly-extending section  550   b . The regions  542   b ,  544   b ,  546   b  and sections  548   b ,  550   b  can be similar, or the same, as regions  542   a ,  544   a ,  546   a  and sections  548   a ,  550   a  described above in connection with prosthesis  500   a  illustrated in  FIG.  11 A . Portions of the outer frame  540   b , such as the upper region  542   b , can be attached to the inner frame  520   b  at or proximate an upper region  522   b  of the inner frame  520   b . As shown in the illustrated embodiment, the outer frame  540   b  can be sized such that a lower end of the outer frame  540   b  is above an upper end or tip  526   b  of anchoring feature  524   b . 
     With reference next to the prosthesis  500   c  illustrated in  FIG.  11 C , outer frame  540   c  can include an upper region  542   c , an intermediate region  544   c , and a lower region  546   c . Portions of the outer frame  540   c , such as the upper region  542   c , can be attached to the inner frame  520   c  at or proximate an upper region  522   c  of the inner frame  520   c . The upper region  542   c  can include a longitudinally-extending section  548   c  and an outwardly-extending section  550   c . The intermediate region  544   c  can extend from the outwardly-extending section  550   c . As shown in the illustrated embodiment, the intermediate region  544   c  can extend in a direction generally parallel to a longitudinal axis of the prosthesis  500   c . The lower region  546   c  can extend from the intermediate region  544   c . As shown in the illustrated embodiment, the lower region  546   c  can bend to extend radially outwardly away from the longitudinal axis of the prosthesis  500   c . The lower region  546   c  can continue to bend such that a tip or end  552   c  of the lower region  546   c  extends upwardly. For example, the tip or end  552   c  of the lower region  546   c  can extend upwardly in a direction generally parallel to the longitudinal axis of the prosthesis  500   c . 
     In some embodiments, the lower region  546   c  can function similarly to anchoring features described herein such as, but not limited to, anchoring features  124 ,  224 . The tips or ends  552   c  as described above can be positioned to contact or engage a native mitral valve annulus on a ventricular side, tissue beyond the native valve annulus on a ventricular side, native leaflets on a ventricular side, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. For example, the tips or ends  552   c  can be positioned to contact a ventricular side of the native mitral valve annulus and/or tissue beyond the ventricular side of the native valve annulus. In some embodiments, the tips or ends  552   c  can advantageously provide atraumatic surfaces that may be used to contact or engage intralumenal tissue without causing unnecessary or undesired trauma to tissue. For example, the tips or ends  552   c  can form flat, substantially flat, curved or other non-sharp surfaces to allow the tips to engage and/or grasp tissue, without necessarily piercing or puncturing through tissue. A looped end or looped anchor may assist the frame in not getting caught up on structures at or near the treatment location. 
     With reference next to the prosthesis  500   d  illustrated in  FIG.  11 D , outer frame  540   d  can include an upper region  542   d , an intermediate region  544   d , and a lower region  546   d . As shown in the illustrated embodiment, the outer frame  540   d  can have a generally bulbous shape with a diameter of the intermediate region  544   d  being greater than the diameter of the upper region  542   d  and the diameter of the lower region  546   d . Moreover, as shown in the illustrated embodiment, the diameter of the upper region  542   d  can be larger than the diameter of the lower region  546   d . 
     Portions of the outer frame  540   d , such as the lower region  546   d , can be attached to the inner frame  520   d  at or proximate a lower region  522   d  of the inner frame  520   d . As shown in the illustrated embodiment, the outer frame  540   d  can be sized such that an upper end of the outer frame  540   d  is at or proximate a plane orthogonal to the longitudinal axis of the prosthesis  500   d  which passes through the upper end of the inner frame  520   d . The outer frame  540   d  can be sized such that a lower end of the outer frame  540   d  is axially below the tips or ends  526   d  of the inner frame anchoring feature  524   d . The outer frame  540   d  can be sized such that a diameter of the widest portion of the outer frame  540   d  is greater than a widest portion of the inner frame anchoring feature  524   d . 
     With reference next to the prosthesis  500   e  illustrated in  FIG.  11 E , outer frame  540   e  can include an upper region  542   e , an intermediate region  544   e , and a lower region  546   e . As shown in the illustrated embodiment, the outer frame  540   e  can have a generally bulbous shape with a diameter of the intermediate region  544   e  being greater than the diameter of the upper region  542   e  and the diameter of the lower region  546   e . Moreover, as shown in the illustrated embodiment, the diameter of the upper region  542   e  can be larger than the diameter of the lower region  546   e . 
     Portions of the outer frame  540   e , such as the lower region  546   e , can be attached to the inner frame  520   e  at or proximate a lower region  522   e  of the inner frame  520   e . As shown in the illustrated embodiment, the outer frame  540   e  can be sized such that an upper end of the outer frame  540   e  is below a plane orthogonal to the longitudinal axis of the prosthesis  500   e  which passes through the upper end of the inner frame  520   e . The outer frame  540   e  can be sized such that a lower end of the outer frame  540   e  is axially below the tips or ends  526   e  of the inner frame anchoring feature  524   e . The outer frame  540   e  can be sized such that a diameter of the widest portion of the outer frame  540   e  is less than a widest portion of the inner frame anchoring feature  524   e . As shown in the illustrated embodiment, the tips  526   e  of the inner anchoring feature  524   e  can be at or proximate an intermediate region  544   e  of the outer frame  540   e . 
     With reference next to the prosthesis  500   f  illustrated in  FIG.  11 F , outer frame  540   f  can include an upper region  542   f , an intermediate region  544   f , and a lower region  546   f . Portions of the outer frame  540   f , such as the intermediate region  544   f  and/or lower region  546   f , can be attached to the inner frame  520   f  at or proximate an intermediate region  522   f  of the inner frame  520   f . 
     The upper region  542   f  can extend downwardly in a direction generally parallel to a longitudinal axis of the prosthesis  500   f . The intermediate region  544   f  can extend from the upper region  542   f . As shown in the illustrated embodiment, the intermediate region  544   f  can extend in a direction radially inward towards the longitudinal axis of the prosthesis  500   f . The lower region  546   f  can extend from the intermediate region  544   f . As shown in the illustrated embodiment, the lower region  546   f  can bend to extend radially outwardly away from the longitudinal axis of the prosthesis  500   f . In some embodiments, the lower region  546   f  can continue to bend such that a tip or end  548   f  of the lower region  546   f  extends upwardly. For example, the tip or end  548   f  of the lower region  546   f  can extend upwardly in a direction generally parallel to the longitudinal axis of the prosthesis  500   f . In some embodiments, the tip or end  548   f  of the lower region  546   f  can extend axially such that it is positioned at or proximate the intermediate region  544   f . 
     In some embodiments, the lower region  546   f  can function similarly to anchoring features described herein such as, but not limited to, anchoring features  124 ,  224 . The tips or ends  548   f  as described above can be positioned to contact or engage a native mitral valve annulus on a ventricular side, tissue beyond the native valve annulus on a ventricular side, native leaflets on a ventricular side, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. For example, the tips or ends  548   f  can be positioned to contact a ventricular side of the native mitral valve annulus and/or tissue beyond the ventricular side of the native valve annulus. In some embodiments, the tips or ends  548   f  can advantageously provide atraumatic surfaces that may be used to contact or engage intralumenal tissue without causing unnecessary or undesired trauma to tissue. For example, the tips or ends  548   f  can form flat, substantially flat, curved or other non-sharp surfaces to allow the tips to engage and/or grasp tissue, without necessarily piercing or puncturing through tissue. A looped end or looped anchor may assist the frame in not getting caught up on structures at or near the treatment location. 
     With reference next to the prosthesis  500   g  illustrated in  FIG.  11 G , outer frame  540   g  can include an upper region  542   g , an intermediate region  544   g , and a lower region  546   g . Portions of the outer frame  540   f , such as the upper region  544   g , can be attached to the inner frame  520   g  at or proximate an upper region  522   g  of the inner frame  520   g . As shown in the illustrated embodiment, the outer frame  540   g  can loosely attached to the inner frame  520   g  via a coupling  560   g  such that the entirety of the outer frame  540   g  is generally movable relative to the entirety of the inner frame  520   g . For example, the coupling  560   g  can be a portion of a skirt attached to both the outer frame  540   g  and the inner frame  520   g . 
     The upper region  542   g  can extend downwardly in a direction generally parallel to a longitudinal axis of the prosthesis  500   g . The intermediate region  544   g  can extend from the upper region  542   g . As shown in the illustrated embodiment, the intermediate region  544   g  can extend in a direction generally downwards such that the intermediate region  544   g  and the upper region  542   g  form a generally cylindrical portion. The lower region  546   g  can extend from the intermediate region  544   g . As shown in the illustrated embodiment, the lower region  546   g  can bend to extend radially inward towards the longitudinal axis of the prosthesis  500   g . In some embodiments, the lower region  546   g  can extend in a direction more perpendicular to the longitudinal axis of the prosthesis  500   g  than parallel. For example, the lower region  546   g  can extend in a direction generally perpendicular to the longitudinal axis of the prosthesis  500   g . 
     With reference next to the prosthesis  500   h  illustrated in  FIG.  11 H , the prosthesis  500   h  can include a lower outer frame  540   h  and an upper outer frame  560   h . The prosthesis  500   h  can be similar to other prostheses described herein, such as prosthesis  500   e  described in connection with  FIG.  11 E . For example, the lower outer frame  540   h  can be similar to outer frame  540   e  described in connection with  FIG.  11 E . As shown in the illustrated embodiment, the lower and upper outer frames  540   h ,  560   h  can form a generally bulbous shape with a diameter of an intermediate region being greater than the diameter of the upper region and the diameter of the lower region. The lower outer frame  540   h  can be attached to the inner frame  520   h  along a lower region of the lower outer frame  540   h . The upper outer frame  560   h  can be attached to the inner frame  520   h  along an upper region of the upper outer frame  540   h . 
     The upper outer frame  560   h  can extend downwardly and extend radially outwardly. As shown, the upper end of the upper outer frame  560   h  can have a diameter which is less than the upper end of the lower outer frame  560   h . The lower end of the upper outer frame  560   h  can have a diameter which is greater than the upper end of the lower outer frame  560   h . As shown, the upper outer frame  560   h  can overlap with a portion of the lower outer frame  540   h  when at least when the prosthesis  500   h  is in a partially or fully expanded state. 
     The shape of the upper outer frame  560   h  can facilitate recapture of the prosthesis  500   h . In some embodiments, the prosthesis  500   h  is sequentially deployed with the lower region of the prosthesis  500   h  being deployed before the upper region of the prosthesis  500   h . For example, a sheath (not shown) maintaining the prosthesis  500   h  in a collapsed or crimped configuration can be retracted upwardly. The upper region of the prosthesis  500   h  can be retained in a collapsed or crimped configuration while the remaining portions of the prosthesis  500   h  are allowed to expand as shown, for example, in  FIG.  56 F . Should a user decide to recapture the prosthesis  500   h  to re-position or remove the prosthesis  500   h , the user may advance the sheath downwardly over the prosthesis  500   h . This process can be facilitated due to the shape and/or attachment of the upper end of the upper outer frame  560   h . Moreover, as the sheath is advanced downwardly, the upper outer frame  560   h  can crimp or collapse over the lower outer frame  540   h  thereby crimping the lower outer frame  540   h . 
     With reference next to the prosthesis  500   i  illustrated in  FIG.  111   , the prosthesis  500   i  can include a lower outer frame  540   i  and an upper outer frame  560   i . The prosthesis  500   i  can be similar to other prostheses described herein, such as prosthesis  500   h  described in connection with  FIG.  11 H . As shown, the upper outer frame  560   i  and the lower outer frame  540   i  can be formed from structures, such as struts, which do not overlap. 
     With reference next to the prosthesis  500   j  illustrated in  FIG.  11 J , outer frame  540   j  can include an upper region  542   j , an intermediate region  544   j , and a lower region  546   j . As shown in the illustrated embodiment, the outer frame  540   j  can have a generally bulbous shape with a diameter of the intermediate region  544   j  being greater than the diameter of the upper region  542   j  and the diameter of the lower region  546   j . Portions of the outer frame  540   j  such as the upper region  542   j  and/or the lower region  546   j , can be attached to the inner frame  520   j  at or proximate an upper region  522   j  and/or lower region  524   j  of the inner frame  520   j . The outer frame  540   j  may be formed from a plurality of struts and/or cells which can allow the outer frame to be crimped or collapsed to a configuration which generally matches the size and/or shape of the inner frame  520   j . For example, when the outer frame  540   j  is in a collapsed configuration, the length of the outer frame  540   j  can generally match that of the inner frame  520   j . When expanded, differences in cell structure between the upper region  542   j , intermediate region  544   j , and the lower region  546   j  can allow the regions to expand to different extents as shown. For example, in some embodiments, the intermediate region  544   j  can have a strut geometry which differs from the strut geometry of the upper and/or lower regions  542   j ,  546   j . 
     The shape of the outer frame  540   j  can facilitate recapture of the prosthesis  500   j . In some embodiments, the prosthesis  500   j  is sequentially deployed with the lower region of the prosthesis  500   h  being deployed before the upper region of the prosthesis  500   h . For example, the upper region of the prosthesis  500   j  can be retained in a collapsed or crimped configuration while the remaining portions of the prosthesis  500   j  are allowed to expand as shown, for example, in  FIG.  56 F . Should a user decide to recapture the prosthesis  500   j  to re-position or remove the prosthesis  500   j , the user may advance the sheath downwardly over the prosthesis  500   j . This process can be facilitated due to the shape and/or attachment of the upper end of the outer frame  540   j . 
     With reference next to the prosthesis  500   k  illustrated in  FIG.  11   k   , outer frame  540   k  can include an upper region  542   k , an intermediate region  544   k , and a lower region  546   k . As shown in the illustrated embodiment, the outer frame  540   k  can have a generally bulbous shape with a diameter of the intermediate region  544   k  being greater than the diameter of the upper region  542   k  and the diameter of the lower region  546   k . The shape of the outer frame  540   k  can facilitate recapture of the prosthesis  500   k  for reasons similar to those described in connection with prosthesis  500   j  shown in  FIG.  11 J . 
     Portions of the outer frame  540   k  such as the upper region  542   k  and/or the lower region  546   k , can be attached to the inner frame  520   k  at or proximate an upper region  522   k  and/or lower region  524   k  of the inner frame  520   k . As shown, the coupling between the upper region  542   k  of the outer frame  540   k  and inner frame  520   k  can be movable. This can facilitate crimping of the outer frame  540   k  since the upper region  542   k  can move independently of the inner frame  520   k . In some embodiments, the upper region  542   k  of the outer frame  540   k  can be coupled to the inner frame  520   k  via a track or rail to allow the upper region  542   k  to slide relative to the inner frame  520   k . This can beneficially maintain the upper end of the outer frame  540   k  at a diameter which matches the diameter of the inner frame  520   k . In some embodiments, the upper region  542   k  of the outer frame  540   k  can be coupled to the inner frame  520   k  via a coupling similar to the coupling  560   g  discussed in connection with  FIG.  11 G . For example, the coupling  560   g  can be a portion of a skirt. Although the coupling between the upper region  542   k  of the outer frame  540   k  and inner frame  520   k  has been described as movable, it is to be understood that the coupling between the lower region  546   k  of the outer frame  540   k  can be movably coupled to the inner frame  520   k  in lieu of, or in combination with, the movable coupling between the upper region  542   k  and the inner frame  520   k . 
     Embodiments of Mesh Anchoring Features 
     In some embodiments, the prostheses described herein can incorporate a mesh or braided anchoring feature. It is to be understood that the mesh or braided anchoring features can be used in combination with other anchoring features described herein or as a replacement for one or more of the anchoring features described herein. 
     With reference next to  FIGS.  12 - 14   , an embodiment of a prosthesis  600  in an expanded configuration is illustrated. The prosthesis  600  can include a frame  620  and a valve body  660 . A longitudinal axis of the prosthesis  600  may be defined as the central axis that extends through the center of the prosthesis  600  between the upper and lower ends of the prosthesis  600 . In some situations, the prosthesis  600  may be oriented such that an upper end of the prosthesis  600  is a proximal portion and a lower end of the prosthesis  600  is a distal portion. The valve body  660  can be similar to, or the same as, other valve bodies described herein such as, but not limited to, valve bodies  160 ,  260 ,  760 ,  870 ,  970 . Accordingly, reference should be made to the discussion of such valve bodies. 
     As shown in the illustrated embodiment, the frame  620  can include a frame body  622  and an anchoring feature  624 . The frame body  622  can include an upper region  626 , an intermediate region  628 , and a lower region  630 . As shown, the frame body  622  can have a generally cylindrical shape such that the diameters of the upper region  626 , the intermediate region  628 , and the lower region  620  are generally constant. However, it is to be understood that the diameters of the upper region  626 , the intermediate region  628 , and/or the lower region  630  can be different. For example, in some embodiments, a diameter of the intermediate region  628  can be larger than the upper region  626  and the lower region  630  such that the frame body  622  has a generally bulbous shape. In some embodiments, the diameter of the lower region  630  can be larger than the diameter of the upper region  626 . In other embodiments, the diameter of the upper region  626  can be larger than the diameter of the lower region  630 . In some situations, the frame  620  may be oriented such that the upper region  626  is a proximal portion and the lower region  630  is a distal portion. Moreover, although the frame body  622  has been described and illustrated as being cylindrical, it is to be understood that all or a portion of the frame body  622  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. The frame body  622  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of frames described herein such as, but not limited to, inner frames  120 ,  220 ,  400 ,  520   a - g . 
     As shown, the anchoring feature  624  can be positioned at or proximate the upper region  626  of the frame body  622 . However, it is to be understood that the anchoring feature  624  can be positioned along other regions of the frame body  622  such as the intermediate region  630  and/or the lower region  628  based on the configuration of the prosthesis  600  and the implantation location. The anchoring feature  624  can include a body portion  632  formed from a wire mesh. The body portion  632  can be positioned such that it is radially outward of the frame body  622 . The body portion  632  can be relatively flexible, resilient, and/or malleable. For example, the construction of the body portion  632 , such as the materials used and/or the geometry of the mesh, can be chosen to provide this flexibility, resilience, and/or flexibility. In some embodiments, the body portion  632  can be formed from a metal including, but not limited to, a shape memory metal such as Nitinol. The body portion  632  can take the form of a braided tube. In some embodiments, the body portion  632  can be formed separately from the other portions of the frame  620 . The body portion  632  can be attached to the frame  620  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the frame  620  and the body portion 632), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. The frame  620  and the body portion  632  can be indirectly attached via an intermediate component, such as a skirt. In other embodiments, the body portion  632  can be integrally or monolithically formed with other portions of the frame  620 . 
     The flexibility, resiliency, and/or malleability of the body portion  632  can beneficially allow the body portion  632  to conform to the anatomy of the body cavity in which it is positioned, such as tissue of a native heart wall, a native valve annulus, and/or leaflets. In some situations, such as when the body portion  632  is positioned within a native mitral valve, the body portion  632  can conform to the shape of the mitral valve annulus such that an upper region of the body portion  632  extends over an atrial side of the native mitral valve annulus, an intermediate region of the body portion  632  conforms to the inner periphery of the native mitral valve annulus, and/or the lower region of the body portion  632  contacts portions of the leaflets. Moreover, the flexibility, resiliency, and/or malleability can beneficially allow the body portion  632  to be crimped to a smaller diameter during the delivery process, thereby allowing for the use of a smaller gauge delivery device. 
     The anchoring feature  624  can include one or more protrusions or barbs  634 . The one or more protrusions  634  can be positioned along the body portion  632 . As shown in the illustrated embodiment, the one or more protrusions  634  can advantageously enhance securement of the anchoring feature  624  to tissue of the body cavity in which the anchoring feature  624  is positioned, such as tissue of a native heart wall, a native valve annulus, and/or native leaflets. In some instances, the protrusions  634  can be oriented to inhibit or limit upward movement of the prosthesis  600 . For example, in situations where the prosthesis  600  is positioned within a native mitral valve, the protrusions  634  can be oriented to inhibit or limit upward movement of the prosthesis  600  during systole. Moreover, the one or more protrusions  634  can beneficially encourage tissue ingrowth by activating the fibroblasts and inducing tissue proliferation. The length and directionality of the protrusions  634  can be chosen to reduce trauma yet provide adequate engagement with tissue and adequate tissue ingrowth. 
     The anchoring feature  624  can include one or more arms or paddles  636 . As shown, the anchoring feature  624  can include eight arms or paddles  636 , however, it is to be understood that the anchoring feature  624  can include a greater or fewer number of arms or paddles. The arms or paddles  636  can be attached at or proximate an upper region  626  of the frame body  622 . The arms or paddles  638  can extend radially outward relative to the longitudinal axis of the prosthesis  600 . As shown in the illustrated embodiment, the arms or paddles  636  can be positioned to extend above the body portion  632 . The arms or paddles  636  can be formed from a wire mesh. The arms or paddles  636  can be relatively flexible, resilient, and/or malleable. For example, the construction of the arms or paddles  636 , such as the materials used and/or the geometry of the mesh, can be chosen to provide this flexibility, resilience, and/or flexibility. The construction of the arms or paddles  636  can be chosen to provide adequate engagement with tissue while is use while reducing the forces exerted by the prosthesis  600  while in a collapsed or crimped configuration. 
     In some embodiments, the arms or paddles  636  can be formed from a metal including, but not limited to, a shape memory metal such as Nitinol. The arms or paddles  636  can be braided. In some embodiments, the arms or paddles  636  can be formed separately from the other portions of the frame  620  such as the body portion  632 . The arms or paddles  636  can be attached to other portions of the frame  620  such as the body portion  632  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the arms or paddles  636  and other portions of the frame  620 ), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. The arms or paddles  636  and other portions of the frame  620  can be indirectly attached via an intermediate component, such as a skirt. In other embodiments, the arms or paddles  636  can be integrally or monolithically formed with other portions of the frame  620  and/or body portion  632 . 
     The flexibility, resiliency, and/or malleability of the arms or paddles  636  can beneficially allow the arms or paddles  636  to conform to the anatomy of the body cavity in which it is positioned, such as tissue of a native heart wall, a native valve annulus, and/or leaflets. In some situations, such as when the arms or paddles  636  are positioned within a native mitral valve, the arms or paddles  636  can conform to the shape of the atrial wall. Moreover, the flexibility, resiliency, and/or malleability can beneficially allow the body portion  632  to be crimped to a smaller diameter during the delivery process, thereby allowing for the use of a smaller gauge delivery device. 
     Although not shown, the frame body  622  can include an anchoring feature positioned below the anchoring feature  624 . The anchoring feature can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of anchoring features described herein including, but not limited to, inner frame anchoring features  124 ,  224 ,  524   d ,  524   e  and lower frame anchoring features  726 ,  826 ,  926 ,  1106 ,  1220 . 
     With reference next to  FIG.  15   , an embodiment of a prosthesis  700  in an expanded configuration is illustrated. The prosthesis  700  can include a frame  720 , a valve body  760 , and a skirt  780 . A longitudinal axis of the prosthesis  700  may be defined as the central axis that extends through the center of the prosthesis  700  between the upper and lower ends of the prosthesis  700 . In some situations, the prosthesis  700  may be oriented such that an upper end of the prosthesis  700  is a proximal portion and a lower end of the prosthesis  700  is a distal portion. The valve body  760  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other valve bodies described herein such as, but not limited to, valve bodies  160 ,  260 ,  660 ,  870 ,  970 . 
     The frame  720  can include a frame body  722 , an upper anchoring feature  724 , a lower anchoring feature  726 , and an intermediate anchoring feature  728 . The frame body  722  can include an upper region  730 , an intermediate region  732 , and a lower region  734 . As shown, the frame body  722  can have a generally cylindrical shape such that the diameters of the upper region  730 , the intermediate region  732 , and the lower region  734  are generally constant. However, it is to be understood that the diameters of the upper region  730 , the intermediate region  732 , and/or the lower region  734  can be different. For example, in some embodiments, a diameter of the intermediate region  732  can be larger than the upper region  730  and the lower region  734  such that the frame body  722  has a generally bulbous shape. In some embodiments, the diameter of the lower region  734  can be larger than the diameter of the upper region  730 . In other embodiments, the diameter of the upper region  730  can be larger than the diameter of the lower region  734 . Moreover, although the frame body  722  has been described and illustrated as being cylindrical, it is to be understood that all or a portion of the frame body  722  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. The frame body  722  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of frame such as inner frames  120 ,  220 ,  400 ,  520   a - g . 
     The upper anchoring feature  724  can extend radially outward from the longitudinal axis of the prosthesis  700 . In this manner, upper anchoring feature  724  can create a flared or shoulder portion  736  of the frame  720 . As shown in the illustrated embodiment, a portion of the upper anchoring feature  724  can extend radially outward via a bend  738  beginning at or proximate the upper end of the upper region  730  of the frame body  722 . The bend  738  can be about a circumferential axis such that the upper anchoring feature  724  extends in a direction more perpendicular to the longitudinal axis of the prosthesis  700  than the frame body  722 . In some embodiments, the bend  738  can generally form an arc with an angle between about 20 degrees to about 90 degrees. For example, as shown in the illustrated embodiment, the arc can have an angle of about 60 degrees. In some embodiments, the bend  738  can form an arc with an angle between about 30 degrees to about 70 degrees. The radius of curvature of the arc may be constant such that the bend  738  forms a circular arc or may differ along the length of the bend  738 . 
     The upper anchoring feature  724  can include a second bend  740  above the bend  738 . The bend  740  can be about a circumferential axis such that the portion of the upper anchoring feature  724  above the second bend  740  extends in a direction less perpendicular to the longitudinal axis of the prosthesis  700  than the portion of the upper anchoring feature  724  below the second bend  740 . In some embodiments, the bend  740  can continue such that the end of the upper anchoring feature  724  extends in a direction radially towards the longitudinal axis of the prosthesis  700 . In some embodiments, the second bend  740  can generally form an arc with an angle between about 20 degrees to about 90 degrees. For example, as shown in the illustrated embodiment, the arc can have an angle of about 90 degrees. In some embodiments, the second bend  740  can form an arc with an angle between about 45 degrees to about 135 degrees. The radius of curvature of the arc may be constant such that the second bend  740  forms a circular arc or may differ along the length of the second bend  740 . 
     With continued reference to the frame  720  illustrated in  FIG.  15   , the lower anchoring feature  726  can extend generally downwardly from above a lower end of the lower region  734  of the inner frame body  722  and/or generally radially outward of the longitudinal axis of the prosthesis  700 . As shown in the illustrated embodiment, the lower anchoring feature  726  can also extend upwardly towards an end  742  of the lower anchoring feature  726 . As will be discussed in further detail below, components of the frame  120 , such as the lower anchoring feature  726 , can be used to attach or secure the prosthesis  700  to a native valve. For example, in some embodiments, the lower anchoring feature  726  can be used to attach or secure the prosthesis  700  to a native valve, such as a native mitral valve. In such an embodiment, the lower anchoring feature  726  can be positioned to contact or engage a native mitral valve annulus on a ventricular side, tissue beyond the native valve annulus on a ventricular side, native leaflets on a ventricular side, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. The lower anchoring feature  726  can beneficially eliminate, inhibit, or limit upward movement of the prosthesis  700  when subject to upwardly directed forces such as those which are applied on the prosthesis  700  during systole. 
     The intermediate anchoring feature  728  can be positioned at or proximate the intermediate region  732  of the frame body  722 . The intermediate anchoring feature  728  can be positioned such that it is radially outward of the frame body  722 . The intermediate anchoring feature  728  can be relatively flexible, resilient, and/or malleable. For example, the construction of the intermediate anchoring feature  728 , such as the materials used and/or the geometry of the mesh, can be chosen to provide this flexibility, resilience, and/or flexibility. In some embodiments, the intermediate anchoring feature  728  can be formed from a metal such as, but not limited to, stainless steel, cobalt-chrome, and a shape memory metal such as Nitinol. The intermediate anchoring portion  728  can take the form of a wire mesh. In some embodiments, the intermediate anchoring portion  728  can be formed separately from the other portions of the frame  720 . The intermediate anchoring portion  728  can be attached to other portions of the frame  720  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the frame  720  and the intermediate anchoring feature  728 ), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. The frame  720  and the intermediate anchoring feature  728  can be indirectly attached via an intermediate component, such as the skirt  780 . In some embodiments, the intermediate anchoring feature  728  can be maintained in position by wrapping the skirt  780  over the intermediate anchoring feature  728  and attaching ends of the skirt  780  to the frame  720 . In some embodiments, the intermediate anchoring portion  728  can be integrally or monolithically formed with other portions of the frame  720 . 
     The flexibility, resiliency, and/or malleability of the intermediate anchoring feature  728  can beneficially allow the intermediate anchoring feature  728  to conform to the anatomy of the body cavity in which it is positioned, such as tissue of a native heart wall, a native valve annulus, and/or leaflets. In some situations, such as when the intermediate anchoring feature  728  is positioned within a native mitral valve, the intermediate anchoring feature  728  can conform to the shape of the mitral valve annulus such that the anchoring feature  728  contacts or extends over one or more of: an atrial side of the native mitral valve annulus, an inner periphery of the native mitral valve annulus, and portions of the leaflets. Moreover, the flexibility, resiliency, and/or malleability can beneficially allow the intermediate anchoring feature  728  to be crimped to a smaller diameter during the delivery process, thereby allowing for the use of a smaller gauge delivery device. 
     As shown in the illustrated embodiment, at least a portion of the intermediate anchoring feature  728  can be positioned radially between the lower anchoring feature  726  and the frame body  722 . In this manner, tissue of the body cavity can be positioned between the lower anchoring feature  726  and the intermediate anchoring feature  728 . In some embodiments, portions of the lower anchoring feature  726  and the intermediate anchoring feature  728  are sufficiently proximate each other such that tissue of the body cavity positioned therebetween are pinched or engaged. For example, in situations where the prosthesis  700  is positioned within a native mitral valve, the native mitral valve annulus and/or leaflets can be pinched or engaged between the lower anchoring feature  726  and the intermediate anchoring feature  728 . This can beneficially enhance securement of the prosthesis  700  to the body cavity. As shown in the illustrated embodiment, a diameter of the intermediate anchoring feature  728  can be greater at or proximate tips or ends of the lower anchoring feature  726  and can have a reduced diameter near a lower end of the intermediate anchoring feature  728 . This can beneficially allow for a greater degree of pinching or clamping force at or proximate the tips of the lower anchoring feature  726  while providing substantial space for tissue of the body cavity, such as native leaflets, positioned between the frame body  722 , the lower anchoring feature  728 , and the intermediate anchoring feature  728 . 
     As noted above, one or more of anchoring features  724 ,  726 ,  728  can contact or engage a native valve annulus, such as the native mitral valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location. In instances where the prosthesis  700  is positioned within a native mitral valve, the upper anchoring feature  724  can be positioned on an atrial side of the native mitral valve annulus, the lower anchoring feature  726  can be positioned on a ventricular side of the native mitral valve annulus, and the intermediate anchoring feature  728  can be positioned intra-annularly. While the anchoring features  724 ,  726 ,  728  have been illustrated as extending from the upper region  730 , the lower region  734 , and the intermediate region  732  of the frame body  722  respectively, it should be understood that the anchoring features  724 ,  726 ,  728  can be positioned along any other portion of the frame body  722  as desired. Moreover, while three anchoring features  724 ,  726 ,  728  have been included in the illustrated embodiment, it is contemplated that fewer or greater sets of anchoring features can be utilized. 
     The anchoring features  724 ,  726 ,  728  are preferably located along the prosthesis  700  with at least part of the foreshortening portion positioned between the anchoring features  724 ,  726 ,  728  so that a portion of the anchoring features  724 ,  726 ,  728  will move closer together with expansion of the prosthesis  700 . As one example, this can allow the anchoring features  724 ,  726 ,  728  to close in on opposite sides of the native mitral annulus to thereby secure the prosthesis at the mitral valve. In some embodiments, the anchoring features  724 ,  726 ,  728  can be positioned such that the anchoring features  724 ,  726 ,  728  do not contact opposing portions of the native mitral annulus at the same time. For example, in some situations, the intermediate anchoring feature  726  and the upper anchoring feature  728  may contact the native mitral annulus while the upper anchoring feature  724  may not contact the native mitral annulus. This can be beneficial when upper anchoring feature  724  is used to provide stabilization and help align the prosthesis. In some embodiments, the anchoring features  724 ,  726 ,  728  can be positioned such that the anchoring features  724 ,  726  grasp opposite side of the native mitral annulus. 
     With reference next to the skirt  780  illustrated in  FIG.  15   , the skirt  780  can be attached to frame  720  and/or the valve body  760 . The skirt  780  can be positioned around and secured to a portion of, or the entirety of, the exterior and/or interior of the frame  720 . As shown, the skirt  780  can extend from the valve body  760  and extend along an interior of the upper anchoring feature  724 . This can beneficially serve as a collector or funnel to direct blood into the inlet of the valve body  760 . The skirt  780  can wrap around the ends of the upper anchoring feature  724  and extend downwardly. As shown, the skirt  780  can extend between the lower anchoring feature  726  and the intermediate anchoring feature  728 . The skirt  780  can be attached to the frame  720  and/or the valve body  760  below the intermediate anchoring feature  728 . 
     The skirt  780  can be annular and can extend entirely circumferentially around the frame  720 . The skirt  780  can prevent or inhibit backflow of fluids, such as blood, around the prosthesis  700 . For example, with the skirt  780  positioned annularly around an exterior of the frame  720 , the skirt  780  can create an axial barrier to fluid flow exterior to the frame  720  when deployed within a body cavity such as a native valve annulus. The skirt  780  can encourage tissue in-growth between the skirt  780  and the natural tissue of the body cavity. This may further help to prevent leakage of blood flow around the prosthesis  700  and can provide further securement of the prosthesis  700  to the body cavity. In some embodiments, the skirt  780  can be tautly attached to the frame  720  such that the skirt  780  is generally not movable relative to the frame  720 . In some embodiments, the skirt  780  can be loosely attached to the frame  720  such that the skirt  780  is movable relative to the frame  720 . In some embodiments, blood may be allowed to flow into the skirt  780 . 
     Although the prosthesis  700  has been described as including a frame  720 , a valve body  760 , and a skirt  780 , it is to be understood that the prosthesis  700  need not include all components. For example, in some embodiments, the prosthesis  700  can include the frame  720  and the valve body  760  while omitting the skirt  780 . Moreover, although the components of the prosthesis  700  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  700  can be integrally or monolithically formed. 
     With reference next to  FIGS.  16 - 19   , an embodiment of a prosthesis  800  in an expanded configuration, or components of the prosthesis  800 , are illustrated. The prosthesis  800  can include a frame  820 , a valve body  870 , and a skirt  890 . A longitudinal axis of the prosthesis  800  may be defined as the central axis that extends through the center of the prosthesis  800  between the upper and lower ends of the prosthesis  800 . In some situations, the prosthesis  800  may be oriented such that an upper end of the prosthesis  800  is a proximal portion and a lower end of the prosthesis  800  is a distal portion. 
     With reference first to the frame  820  illustrated in  FIGS.  18 - 19   , the frame  820  can include a frame body  822 , an upper anchoring feature  824 , a lower anchoring feature  826 , and an intermediate anchoring feature  828 . The frame body  822  can include an upper region  830 , an intermediate region  832 , and a lower region  834 . As shown, the frame body  822  can have a generally cylindrical shape such that the diameters of the upper region  830 , the intermediate region  832 , and the lower region  834  are generally constant. However, it is to be understood that the diameters of the upper region  830 , the intermediate region  832 , and/or the lower region  834  can be different. 
     In some embodiments, the diameter of the frame body  822  may be between about 40% to about 90% of the diameter of the native valve annulus, between about 60% to about 85%, of the diameter of the native valve annulus, between about 70% to about 80% of the diameter of the native valve annulus, any other sub-range between these ranges, or any other percentage as desired. In some embodiments, the diameter of the frame body  822  can be in the range of about 20 mm to about 40 mm when expanded, in the range of about 25 mm to about 35 mm when expanded, in the range of about 28 mm to about 32 mm when expanded, about 29 mm when expanded, any other sub-range within these ranges when expanded, or any other diameter when expanded as desired. Although the frame body  822  has been described and illustrated as being cylindrical or having circular cross-sections, it is to be understood that all or a portion of the frame body  822  can be have a non-circular cross-section such as, but not limited to, a D-shape, an oval or an otherwise ovoid cross-sectional shape. 
     In other embodiments, the diameter of portions of the frame body  822  such as the upper region  830 , intermediate region  832 , and/or lower region  834  may be chosen such that the frame body  822  is positioned at the periphery of the body cavity. For example, in embodiments where the prosthesis  800  is positioned within the native mitral valve, the inner frame body  822  may have a diameter which is about equal to the diameter of the native mitral valve annulus. 
     The frame  822  can include a plurality of struts with at least some of the struts forming cells  836   a - b . Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. 
     The upper and lower row of cells  836   a - b  can have a diamond or generally diamond shape. The rows of cells  836   a - b  can be formed via a combination of struts. As shown in the illustrated embodiment, the upper row of cells  836   a  can be formed from a first set of circumferentially-expansible struts  838   a  and a second set of circumferentially-expansible struts  838   b . The lower row of cells  836   b  can be formed from the second set of circumferentially-expansible struts  838   b  and a third set of circumferentially-expansible struts  838   c . The first, second, and third sets of struts 838a-c can have a zig-zag or undulating shape forming a repeating “V” shape. It is to be understood that some or all of the struts 838a-c may not form entirely straight segments. For example, the struts 838a-c can include some curvature such that the upper and/or lower apices are curved. 
     As shown in the illustrated embodiment, the upper and lower row of cells  836   a - b  extend in a direction generally parallel to the longitudinal axis of the prosthesis  800 . There can be a row of nine cells  836   a  and a row of nine cells  836   b . While each of the cells  836   a - b  are shown as having the same shape as other cells  836   a - b  of the same row, it is to be understood that the shapes of cells  836   a - b  within a row can differ. Moreover, it is to be understood that any number of rows of cells can be used and any number of cells may be contained in the rows. In some embodiments, the number of cells can correspond to the number of anchors or anchor tips forming the upper anchoring feature  824  and/or the lower anchoring feature  826 . The number of cells in the upper and lower row of cells  836   a - b  can have a 1:1 correspondence with the number of anchors in the upper anchoring feature  824  and/or the lower anchoring feature  826  (i.e., nine cells in each row of cells  836   a - b  and nine anchors for the anchoring features  824 , 826). It is to be understood that other ratios of numbers of cells per row to number of anchors per anchoring feature can be used such as, but not limited to, 3:1, 4:1, 5:1, 6:1, and other ratios as desired. In some embodiments, all three rows of cells  836   a - b  can have different numbers of cells. Moreover, it is to be understood that fewer or greater numbers of rows of cells can be used. 
     The geometry of cells  836   a - b  can allow the cells  836   a - b  to foreshorten as the frame  820  is expanded. As such, one or more of cells  836   a - b  can allow the frame  820  to foreshorten as the frame  820  is expanded. As described herein, foreshortening of the frame  820  can be used to secure the prosthesis to intralumenal tissue in a body cavity, for example tissue at or adjacent a native valve, such as a native valve annulus and/or leaflets. For example, expansion of the frame  820  can allow the upper frame anchoring feature  824 , the lower anchoring feature  826 , and/or the intermediate anchoring feature  828  to extend radially outward and draw closer to tissue of the body cavity, such as a native valve annulus and/or leaflets, to engage tissue of the body cavity. 
     The frame  820  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of frames such as inner frames  120 ,  220 ,  400 ,  520   a - g ,  720 . 
     As shown in the illustrated embodiment, the upper anchoring feature  824  can extend radially outwardly from the longitudinal axis of the prosthesis  800 . In this manner, upper anchoring feature  824  can create a flared or shoulder portion  840  of the frame  820 . As shown in the illustrated embodiment, the upper anchoring feature  824  can include one or more anchors  842   a - b . The anchors  842   a - b  can extend from below an upper end of the frame body  822 . For example, the anchors  842   a - b  can extend from a portion of the frame body  822  between the upper row of cells  836   a . However, it is to be understood that the anchors  842   a - b  can extend from other portions of the frame body  822 , such as upper apices of the upper row of cells  836   a . 
     The anchors  842   a - b  can extend upwardly from the frame body  822 . The anchors  842   a - b  can then extend radially outwardly via a bend  844 . The bend  844  can be about a circumferential axis such that the anchors  842   a - b  extend in a direction more perpendicular to the longitudinal axis of the prosthesis  800  than the frame body  822 . The bend  844  can be similar to the bend  738  discussed above in connection with prosthesis  700  illustrated in  FIG.  15   . 
     As shown, anchors  842   a ,  842   b  can include a second bend  846  above the bend  844 . The bend  846  can be a clockwise bend about a circumferential axis such that the portion of the anchors  842   a ,  842   b  above the second bend  846  extends in a direction less perpendicular to the longitudinal axis of the prosthesis  800  than the portion of the anchors  842   a ,  842   b  below the second bend  846 . The bend  846  can be similar to the bend  740  discussed above in connection with prosthesis  700  illustrated in  FIG.  15   . 
     Some anchors of the upper anchoring feature  824 , such as anchors  842   b , can have a greater length than other anchors of the upper anchoring feature  824 , such as anchors  842   a . As shown, anchors  842   b  can include a third bend  848  above the bend  846 . The bend  848  can be about a circumferential axis such that the portion of the anchors  842   b  above the third bend  848  extends in a direction radially towards the longitudinal axis of the prosthesis  800 . This can beneficially reduce the likelihood that the anchors  842   b  contact tissue of the body cavity. For example, in situations where the prosthesis  800  is positioned within a native mitral valve, the radially inward bend can reduce the likelihood of anchors  842   b  contacting the atrial wall. 
     In some embodiments, portions of anchors  842   b  can form part of a locking tab  850  having a strut  850   a  and an enlarged head  850   b . The locking tab  850  can advantageously be used with multiple types of delivery systems. For example, the shape of the strut  850   a  and the enlarged head  850   b  can be used to secure the frame  850  to a “slot” based delivery system. The locking tabs  850  can include eyelets which can be used to secure the frame  820  to a “tether” based delivery system such as those which utilize sutures, wires, or fingers to control delivery of the frame  820 . This can advantageously facilitate recapture and repositioning of the frame  820  in situ. In some embodiments, the frame  820  can be used with the delivery systems described herein, including but not limited to, those described in U.S. Pat. Nos. 8,414,644 and 8,652,203 and U.S. Publication Nos. 2015/0238315, the entireties of each of which are hereby incorporated by reference and made a part of this specification. 
     With continued reference to the frame  820  illustrated in  FIGS.  18 - 19   , the lower anchoring feature  826  can include one or more anchors  854 . The anchors  854  can extend generally downwardly from above a lower end of the lower region  814  of the frame body  822 . For example, the anchors  854  can extend from a portion of the frame body  822  between the lower row of cells  836   b . However, it is to be understood that the anchors  854  can extend from other portions of the frame body  822 , such as lower apices of the lower row of cells  836   b . The anchors  854  can bend to extend generally radially outward of the longitudinal axis of the prosthesis  800 . The anchors can extend upwardly towards an end or tip  856 . 
     The anchors  854  can be used to attach or secure the prosthesis  800  to a native valve. For example, in some embodiments, the anchors  854  can be used to attach or secure the prosthesis  800  to a native valve, such as a native mitral valve. In such an embodiment, the anchors  854  can be positioned to contact or engage a native mitral valve annulus on a ventricular side, tissue beyond the native valve annulus on a ventricular side, native leaflets, and/or other tissue at or around the implantation location during one or more phases of the cardiac cycle, such as systole and/or diastole. The anchors  854  can beneficially eliminate, inhibit, or limit upward movement of the prosthesis  800  when subject to upwardly directed forces such as those which are applied on the prosthesis  800  during systole. 
     The tips or ends of the anchors  842   a - b ,  854  can advantageously provide atraumatic surfaces that may be used to contact or engage intralumenal tissue without causing unnecessary or undesired trauma to tissue. For example, the tips or ends can form flat, substantially flat, curved or other non-sharp surfaces to allow the tips to engage and/or grasp tissue, without necessarily piercing or puncturing through tissue. A looped end or looped anchor may assist the frame in not getting caught up on structures at or near the treatment location. For example, each loop can be configured so that when the prosthesis  800  is deployed in-situ and the anchors  842   a - b ,  854  expand away from the frame body  822 , the movement of each loop from a delivered position to a deployed position avoids getting caught on the papillary muscles. As shown in the illustrated embodiment, the anchors  854  can include eyelets or holes  858  at or proximate the tips or ends. The eyelets or holes  858  can facilitate attachment of component, such as a cover and/or cushion, the tips or ends  856  of the anchors  842   a - b ,  854 . 
     As shown in the illustrated embodiment, the upper and lower anchoring features  824 ,  826  can include twelve individual anchors; however, it is to be understood that a greater number or lesser number of individual anchors can be used. For example, the number of individual anchors can be chosen as a multiple of the number of commissures for the valve body  870 . As such, for a prosthesis  800  with a valve body  870  having three commissures, the upper anchoring feature  824  and/or the lower anchoring feature  826  can have three individual anchors (1:1 ratio), six individual anchors (2:1 ratio), nine individual anchors (3:1 ratio), twelve individual anchors (4:1 ratio), fifteen individual anchors (5:1 ratio), or any other multiple of three. It is to be understood that the number of individual anchors need not correspond to the number of commissures of the valve body  870 . 
     Moreover, while the prosthesis  800  includes anchoring features  824 ,  826  with twelve anchors each, it is to be understood that a greater number of anchors or a lesser number of anchors can be used. In some embodiments, instead of a 1:1 correspondence between the number of anchors in the upper frame anchoring feature  824  and the lower anchoring feature  826  (i.e., twelve anchors each), other ratios can be used. For example, a 1:2 or a 1:3 correspondence between the anchors, are possible such that the upper anchoring feature  824  or the lower anchoring feature  826  have fewer anchors than the other anchoring feature. 
     The intermediate anchoring feature  828  can be positioned at or proximate the intermediate region  832  of the frame body  822 . The intermediate anchoring feature  828  can be positioned such that it is radially outward of the frame body  822 . The intermediate anchoring feature  828  can be relatively flexible, resilient, and/or malleable. For example, the construction of the intermediate anchoring feature  828 , such as the materials used and/or the geometry of the mesh, can be chosen to provide this flexibility, resilience, and/or flexibility. In some embodiments, the intermediate anchoring feature  828  can be formed from a metal such as, but not limited to, stainless steel, cobalt-chrome, and a shape memory metal such as Nitinol. The intermediate anchoring portion  828  can take the form of a wire mesh. In some embodiments, the intermediate anchoring portion  828  can be formed separately from the other portions of the frame  820 . The intermediate anchoring portion  828  can be attached to other portions of the frame  820  using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots which can be on the frame  820  and the intermediate anchoring feature 828), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. For example, in embodiments having a braided mesh with loops, sutures can be used to connect the edge loops to the frame body  822 . The frame  820  and the intermediate anchoring feature  828  can be indirectly attached via an intermediate component, such as the skirt  890 . In some embodiments, the intermediate anchoring feature  828  can be maintained in position by wrapping the skirt  890  over the intermediate anchoring feature  828  and attaching ends of the skirt  890  to the frame  820 . In some embodiments, the intermediate anchoring portion  828  can be integrally or monolithically formed with other portions of the frame  820 . 
     The flexibility, resiliency, and/or malleability of the intermediate anchoring feature  828  can beneficially allow the intermediate anchoring feature  828  to conform to the anatomy of the body cavity in which it is positioned, such as tissue of a native heart wall, a native valve annulus, and/or leaflets. In some situations, such as when the intermediate anchoring feature  828  is positioned within a native mitral valve, the intermediate anchoring feature  828  can conform to the shape of the mitral valve annulus such that an upper region of the intermediate anchoring feature  828  extends over an atrial side of the native mitral valve annulus, an intermediate region of the intermediate anchoring feature  828  conforms to the inner periphery of the native mitral valve annulus, and/or the lower region of the intermediate anchoring feature  828  contacts portions of the leaflets. Moreover, the flexibility, resiliency, and/or malleability can beneficially allow the intermediate anchoring feature  828  to be crimped to a smaller diameter during the delivery process, thereby allowing for the use of a smaller gauge delivery device. 
     As shown in the illustrated embodiment, at least a portion of the intermediate anchoring feature  828  can be positioned radially between the lower anchoring feature  826  and the frame body  822 . In this manner, tissue of the body cavity can be positioned between the lower anchoring feature  826  and the intermediate anchoring feature  828 . In some embodiments, portions of the lower anchoring feature  826  and the intermediate anchoring feature  828  are sufficiently proximate each other such that tissue of the body cavity positioned therebetween are pinched or engaged. For example, in situations where the prosthesis  800  is positioned within a native mitral valve, the native mitral valve annulus and/or leaflets can be pinched or engaged between the lower anchoring feature  826  and the intermediate anchoring feature  828 . This can beneficially enhance securement of the prosthesis  800  to the body cavity. 
     As shown in the illustrated embodiment, the intermediate anchoring feature  828  can have a generally triangular, cross-sectional shape along a plane parallel to and extending through the longitudinal axis of the prosthesis  800 . The intermediate anchoring feature  828  can have a greater diameter at or proximate tips or ends of the lower anchoring feature  826  and a reduced diameter near a lower end of the intermediate anchoring feature  828 . This can beneficially allow for a greater degree of pinching or clamping force at or proximate the tips of the lower anchoring feature  826  while providing substantial space for tissue of the body cavity, such as native leaflets, positioned between the frame body  822 , the lower anchoring feature  826 , and the intermediate anchoring feature  828 . However, it is to be understood that other cross-sectional shapes along a plane parallel to and extending through the longitudinal axis of the prosthesis  800 . For example, the cross-section can be circular, semi-circular, elliptical, semi-elliptical, rectangular, and the like. 
     As noted above, one or more of anchoring features  824 ,  826 ,  828  can contact or engage a native valve annulus, such as the native mitral valve annulus, tissue beyond the native valve annulus, native leaflets, and/or other tissue at or around the implantation location. In instances where the prosthesis  800  is positioned within a native mitral valve, the upper anchoring feature  824  can be positioned on an atrial side of the native mitral valve annulus, the lower anchoring feature  826  can be positioned on a ventricular side of the native mitral valve annulus, and the intermediate anchoring feature  828  can be positioned intra-annularly. While the anchoring features  824 ,  826 ,  828  have been illustrated as extending from the upper region  830 , the lower region  834 , and the intermediate region  832  of the frame body  822  respectively, it should be understood that the anchoring features  824 ,  826 ,  828  can be positioned along any other portion of the frame body  822  as desired. Moreover, while three anchoring features  824 ,  826 ,  828  have been included in the illustrated embodiment, it is contemplated that fewer or greater sets of anchoring features can be utilized. 
     With reference back to the prosthesis  800  illustrated in  FIGS.  16 - 17   , covers  860  and/or cushions  862  can be used to surround or partially surround at least a portion of the anchoring features  824 ,  826 ,  828 , such as anchors of the lower anchoring feature  826 . As shown in the illustrated embodiment, a cover  860  can be positioned around portions of the anchors  854  preceding the tips or ends  856 . A cushion  862  can be positioned to around the tips or ends  856 . The covers  860  and/or cushions  862  can be similar to those described in U.S. Publication No. 2015/032800, which has been incorporated by reference in its entirety. It is to be understood that greater or fewer numbers of covers  860  and/or cushions  862  can be used with anchors  854 . For example, a cover  860  and/or cushion  862  can be used on every other anchor such that there is a 1:2 ratio of covers  860  and/or cushions  862  to anchors 
     The tips or ends  856  of the anchors  854  can be generally circumferentially offset with respect to the tips or ends of the anchors  842   a ,  842   b . In other embodiments (not shown), the tips or ends  856  of the anchors  854  can be generally circumferentially aligned with respect to the tips or ends of the anchors  842   a ,  842   b . 
     Preferably, each of the anchoring features  824 ,  826 ,  828  are positioned or extend generally radially outwardly from the prosthesis  800  so that the tips or ends of the anchoring features  824 ,  826 ,  828  are generally spaced away or radially outward from the rest of the frame body  822 . As shown in the illustrated embodiment, at least some of the anchoring features, such as lower anchoring feature  826 , can extend to a radial distance from an exterior surface of the frame body  822  that is about 120% or more of the expanded diameter of the frame body  822 , that is about 130% or more of the expanded diameter of the frame body  822 , that is about 140% or more of the expanded diameter of the frame body  822 , that is about 150% or more of the expanded diameter of the frame body  822 . 
     In some embodiments, all of the anchors of the lower anchoring feature  826  and/or all of the anchors of the upper frame anchoring feature  824  extend at least to this radial distance. In other embodiments, fewer than all of the anchors of the lower anchoring feature  826  and/or all of the anchors of the upper anchoring feature  824  extend to this radial distance. The outermost diameter of the anchoring features  824 ,  826 ,  828  may be greater than the diameter of frame body  822  as described above and may be in the range of about 35 mm to about 70 mm when expanded, in the range of about 35 mm to about 60 mm when expanded, in the range of about 40 mm to about 60 mm when expanded, in the range of about 45 mm to about 50 mm when expanded, any sub-range within these ranges when expanded, or any other diameter as desired. In some embodiments, the upper anchoring feature  824  can have a diameter of about 49 mm while the lower anchoring feature  826  and the intermediate anchoring feature  828  can have a diameter of about 46 mm. 
     Moreover, as will be discussed in further detail below, the anchoring features  824 ,  826 ,  828  are preferably located along the prosthesis  800  with at least part of the foreshortening portion positioned between the anchoring features  824 ,  826 ,  828  so that a portion of the anchoring features  824 ,  826 ,  828  will move closer together with expansion of the prosthesis  800 . As one example, this can allow the anchoring features  824 ,  826 ,  828  to close in on opposite sides of the native mitral annulus to thereby secure the prosthesis at the mitral valve. In some embodiments, the anchoring features  824 ,  826 ,  828  can be positioned such that the anchoring features  824 ,  826 ,  828  do not contact opposing portions of the native mitral annulus at the same time. For example, in some situations, the intermediate anchoring feature  826  and the upper anchoring feature  828  may contact the native mitral annulus while the upper anchoring feature  824  may not contact the native mitral annulus. This can be beneficial when upper anchoring feature  824  is used to provide stabilization and help align the prosthesis. In some embodiments, the anchoring features  824 ,  826 ,  828  can be positioned such that the anchoring features  824 ,  826  grasp opposite side of the native mitral annulus. 
     With reference next to the valve body  870  illustrated in  FIGS.  16 - 17   , the valve body  870  can be positioned within the frame  820 . The valve body  870  can be a replacement heart valve which includes a plurality of valve leaflets  872 . The valve leaflets  872  can include a first edge  874 , second edge (not shown), and tabs  878  for attaching the valve leaflets  872  together at commissures of the valve body  870 . The tabs  878  can be used to secure the valve leaflets  872  to the frame  820 . The first edge  874  can be an arcuate edge and can be generally fixed in position relative to the frame  820 . The second edge can be a freely moving edge which can allow the valve body  870  to open and close. 
     The plurality of valve leaflets  872  can function in a manner similar to the native mitral valve, or to any other valves in the vascular system as desired. The plurality of valve leaflets  872  can open in a first position and then engage one another to close the valve in a second position. The plurality of valve leaflets  872  can be made to function as a one-way valve such that flow in one direction opens the valve and flow in a second direction opposite the first direction closes the valve. For example, as shown in the illustrated embodiment, the valve body  870  can open allow to blood to flow through the valve body  870  in a direction from an upper end to a lower end. The valve body  870  can close to inhibit blood flow through the valve body  870  in a direction from the lower end to the upper end. In situations where the prosthesis  800  is oriented such that an upper end is a proximal end and a lower end is a distal end, the valve body  870  can be positioned such that the valve body  870  can open to allow blood to flow through the valve body  870  in a proximal-to-distal direction and close to inhibit blood flow in a distal-to-proximal direction. The valve body  870  can be constructed so as to open naturally with the beating of the heart. For example, the valve body  870  can open during diastole and close during systole. The valve body  870  can replace a damaged or diseased native heart valve such as a diseased native mitral valve. 
     With continued reference to the valve body  870  illustrated in  FIGS.  16 - 17   , the valve body  870  can include a liner  880 . The liner  880  can be used to assist with fluid flow through and/or around the prosthesis  880 , such as through and around the inner frame  880  and the valve leaflets  872 . The liner  880  can surround at least a portion of the valve leaflets  872  and be connected to one or more of the valve leaflets  872 . For example, as shown in the illustrated embodiment, the one or more valve leaflets  872  can be attached to the liner  880  along the first edge  874  of the valve leaflets  872 . 
     As shown in the illustrated embodiment, the liner  880  can be positioned within the interior of the inner frame  880  and can form an inner wall of the prosthesis  800 . For example, the liner  880  can be positioned such that the liner  880  is radially inward, relative to the longitudinal axis of the prosthesis  800 , from the struts of the frame  820 . In this manner, the fluid pathway towards the valve leaflets  872  can be relatively smooth. It is also contemplated that the liner  880  can at least be partially positioned along an exterior of the frame  820  such that at least a portion of the liner  880  is radially outward, relative to the longitudinal axis of the prosthesis  800 , from struts of the frame  820 . As shown in the illustrated embodiment, the liner  880  can be positioned along an upper or inlet side of the frame  820 . The liner  880  can extend from the first edge  874  of the valve leaflets  872  towards the upper end of the frame  820 . The liner  880  can also extend below the first edge  874  of the valve leaflet  872  towards the lower end of the frame  820 . The liner  880  can also be made to move with foreshortening portions of the frame  820 . 
     In some embodiments, the liner  880  can extend the entire length of the frame  820  or the frame body  822 . In other embodiments, it can extend along only part of the length of the frame body  822  as shown. In some embodiments, the ends of the valve leaflets  872  can coincide with ends of the liner  880 . In addition, one or more of the ends of the frame body  822  can coincide with the ends of the liner  880 . As shown in the illustrated embodiment, an end  882  of the liner  880  can be positioned between the upper end of the frame  820  and the valve leaflets  872 . The end  882  of the liner  880  can extend above an upper end of the frame body  822 . In some embodiments, the end  882  of the liner  880  can be positioned at or proximate an uppermost portion of the first or arcuate edge  874  of the valve leaflet  872 . 
     Other shapes and configurations can also be used for the valve body  870 . In some embodiments, the liner  880  may extend along the length of the leaflets, but is not connected to them. In the illustrated embodiment, the liner  880  is attached to the frame  820  and at least a portion of the leaflets  872 , such as the first or arcuate edge  874 , is attached to the liner  880 . Portions of the valve leaflets  872 , such as the portions of the first edge  874  and/or tabs  878 , can also be attached to the frame  820 . The liner  880  and/or the valve leaflets  872  can be attached to the frame  820  or to each other using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. 
     The liner  880  can be constructed in multiple different ways. The liner  880  can be made a layer of resilient material, such as such as knit polyester (e.g., polyethylene terephthalate (PET), polyvalerolactone (PVL)) or any other biocompatible material such as those which are wholly or substantially fluid impermeable, flexible, stretchable, deformable, and/or resilient. In some embodiments, the liner  880  can be made from a material that is more flexible than the valve leaflet material. The upper and/or lower end, such as end  882 , of the liner  880  can be straight, curved, or have any other desired configuration. For example, as shown in the illustrated embodiment, the liner  880  can have one or more straight edges  884  and one or more slots  886  forming the end  882 . It is to be understood that the liner  880 , such as the straight edges  884 , can be folded over a top end of the frame body  822 . In other embodiments, the end  882  can be patterned to generally correspond to the undulations at one end of the frame  820 . The liner  880  can be formed of one piece or multiple pieces. 
     In another embodiment of the liner  880 , the end can extend past the frame  820  and can be wrapped around it. Thus, the liner  880  can extend from the inside of the frame  820  to the outside of the frame  820 . The liner  880  can extend completely around the frame  820  for ¼, ⅓, ½, or more of the length of frame  820 . 
     With reference next to the skirt  890  illustrated in  FIGS.  16 - 17   , the skirt  890  can be attached to frame  820  and/or the valve body  870 . The skirt  890  can be positioned around a portion of, or the entirety of, the exterior of the frame  820  and/or the interior of the frame  820 . As shown, the skirt  890  can extend from the valve body  870  and extend along an interior of the upper anchoring feature  824 . The skirt  890  can wrap around the ends of the upper anchoring feature  870 , or a portion thereof, and extend downwardly. For example, the skirt  890  can extend up to and wrap around the ends of the anchors  842   a  but not the ends of anchors  842   b . This can advantageously allow the locking tabs  848  to remain uncovered to facilitate use with a delivery system. As shown, the skirt  890  can extend between the lower anchoring feature  826  and the intermediate anchoring feature  828 . The skirt  890  can be attached to the frame  820  and/or the valve body  870  below the intermediate anchoring feature  828 . 
     The skirt  890  can be annular and can extend entirely circumferentially around the frame  890 . The skirt  890  can prevent or inhibit backflow of fluids, such as blood, around the prosthesis  800 . For example, with the skirt  890  positioned annularly around an exterior of the frame  820 , the skirt  890  can create an axial barrier to fluid flow exterior to the frame  820  when deployed within a body cavity such as a native valve annulus. The skirt  890  can encourage tissue in-growth between the skirt  890  and the natural tissue of the body cavity. This may further help to prevent leakage of blood flow around the prosthesis  800  and can provide further securement of the prosthesis  800  to the body cavity. In some embodiments, the skirt  890  can be tautly attached to the frame  820  and/or valve body  870 . In some embodiments, the skirt  890  can be loosely attached around the frame  820  and/or valve body  870 . In some embodiments, blood may be allowed to flow into the skirt  890 . 
     As shown in the illustrated embodiment, the skirt  890  can have a first portion  892 , a second portion  894 , and a third portion  896 . The first portion  892  can extend along an interior portion of the frame  820 . For example, the first portion  892  can extend from the liner  880  of the valve body  870  and extend along an interior of the frame body  882  and/or the upper anchoring feature  824 . The first portion  892  can extend up to the ends of the anchors  842   a . The first portion  892  can also extend up to the ends of anchors  842   b . 
     The second portion  894  can extend downwardly from an upper end of the first portion  892 . The second portion  894  can extend along an exterior portion of the frame  820 . For example, the second portion  894  can extend along an exterior of the upper anchoring feature  824  and/or the intermediate anchoring feature  828 . The second portion  894  can be attached to the frame  820  at a position between the intermediate anchoring feature  828  and the lower anchoring feature  826 . 
     The third portion  896  can extend along an exterior portion of the frame  820 . For example, the third portion  896  can extend along an exterior of the frame body  822 . The third portion  896  can extend upwardly from a lower end of the frame body  822 . The third portion  896  can extend upwardly towards a lower end of the liner  880 . In some embodiments, the third portion  896  can extend up to, or beyond, the lower end of the liner  880 . As shown in the illustrated embodiment, the third portion  896  can be positioned between the frame body  822  and the intermediate anchoring feature  828 . 
     The first portion  892 , second portion  894 , and third portions  896  can be formed from separate components. The components can be attached using any of the fasteners and/or techniques described herein including, but not limited to, mechanical fasteners, such as sutures, staples, screws, rivets, interfacing members (e.g., tabs and slots), and any other type of mechanical fastener as desired, chemical fasteners such as adhesives and any other type of chemical fastener as desired, fastening techniques such as welding, soldering, sintering, and any other type of fastening technique as desired, and/or a combination of such fasteners and techniques. In some embodiments, the skirt  890  can be formed from additional components. For example, the second portion  894  can be formed from an upper component and a lower component. In some embodiments, two or more portions of the skirt  890  can be integrally or monolithically formed. 
     Although the prosthesis  800  has been described as including a frame  820 , a valve body  870 , and a skirt  890 , it is to be understood that the prosthesis  800  need not include all components. For example, in some embodiments, the prosthesis  800  can include the frame  820  and the valve body  870  while omitting the skirt  890 . Moreover, although the components of the prosthesis  800  have been described and illustrated as separate components, it is to be understood that one or more components of the prosthesis  800  can be integrally or monolithically formed. 
     With reference next to  FIGS.  20 - 22   , an embodiment of a prosthesis  900  in an expanded configuration, or components of the prosthesis  900 , are illustrated. The prosthesis  900   can include a frame  920 , a valve body  970 , and a skirt  990 . A longitudinal axis of the prosthesis  900  may be defined as the central axis that extends through the center of the prosthesis  900  between the upper and lower ends of the prosthesis  900 . The prosthesis  900  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of prosthesis  800  described in connection with  FIGS.  16 - 19   . 
     The frame  920  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of frame  820  described in connection with  FIGS.  16 - 19   . The frame  920  can include a frame body  922 , an upper anchoring feature  924 , a lower anchoring feature  926 , and an intermediate anchoring feature  928 . As shown in the illustrated embodiment, the upper anchoring feature  924  can be formed from a row of circumferentially expansible struts  930 . The circumferentially-expansible struts  930  can be attached to the frame body  922  via one or more struts  932 . The intermediate anchoring feature  928  can be formed from a braided structure. 
     The skirt  990  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of skirt  890  described in connection with  FIGS.  16 - 19   . Accordingly, reference should be made to the discussion of skirt  890  for further details pertaining to the skirt  990 . As shown in  FIG.  20   , the skirt  990  can be formed from multiple components which can be attached together (as shown in  FIG.  21   ). 
     Embodiments of Circumferentially Curved Anchoring Features 
     In some embodiments, the prostheses described herein can incorporate a circumferentially curved or inclined anchoring feature. In some situations, such as those in which the prostheses are implanted at a native mitral valve, the circumferential curve and/or incline can allow a greater number of chordae tendineae to be positioned between a frame body and the curved or inclined anchors. This can beneficially enhance securement of the frame to the native mitral valve. It is to be understood that the circumferentially curved or inclined anchoring feature can be used in combination with other anchoring features described herein or as a replacement for one or more of the anchoring features described herein. 
     With reference next to  FIGS.  23 - 25   , a portion of an embodiment of a frame  1000  is illustrated. The frame  1000  can include a frame body  1002  and an anchoring feature  1004 . A longitudinal axis of the frame  1000  may be defined as the central axis that extends through the center of the frame  1000  between the upper and lower ends of the frame  1000 . Features of the frame  1000  can be incorporated in any of the prostheses described herein. 
     The frame body  1002  can include an upper region  1006 , an intermediate region  1008 , and a lower region  1010 . As shown, the frame body  1002  can include a plurality of struts with at least some of the struts forming cells  1012   a - c . The cells  1012   a - c  can have a diamond or generally diamond shape. However, it is to be understood that the cells  1012   a - c  can have different shapes such as those described in connection with other frames herein. Any number of configurations of struts can be used, such as rings of undulating struts shown forming ellipses, ovals, rounded polygons, and teardrops, but also chevrons, diamonds, curves, and various other shapes. For example, the frame body  1002  can be formed from circumferentially-expansible elements  1014   a - d . While the struts  1014   a - d  are generally described and illustrated as being straight segments, it is to be understood that some or all of the struts  1014   a - d  may not form entirely straight segments. For example, the struts  1014   a - d  can include some curvature such that the upper and/or lower apices are curved. 
     The anchoring feature  1004  can include one or more anchors  1016 . The anchors  1016  can extend from a lower region  1010  of the frame body  1002 . For example, the anchors  1016  can extend downwardly and/or radially outwardly from a lower end of the lower region  1010 . The anchors  1016  can also extend upwardly towards a tip or end  1018 . As shown in the illustrated embodiment, at least a portion of the anchors  1016 , such as the strut  1020  and/or the tip or end  1018 , can be curved and/or inclined in a circumferential direction about the longitudinal axis of the frame  1000 . For example, the portion of the strut  1020  which extends upwardly as well as the tip or end  1018  can be curved as shown in  FIGS.  23  and  24   . As another example, the entirety of the strut  1020   a , including both portions which extend downwardly and upwardly, as well as the tip or end  1018   a  can be curved as shown in  FIG.  25   . 
     As discussed above, some of the anchoring features described herein can be positioned on a ventricular side of the native mitral valve annulus and/or tissue beyond the ventricular side of the annulus. The anchoring features may be positioned in this manner by extending around the native mitral valve leaflets, which include chordae tendineae  60  that connect a downstream end of the native mitral leaflets to the papillary muscle of the left ventricle. As shown in  FIG.  24   , the circumferential curve and/or incline can allow a greater number of chordae tendineae  60  to be positioned between the frame body  1002  and the anchors  1016 . This can beneficially enhance securement of the frame  1000  to the native mitral valve. 
     With reference next to  FIGS.  26  and  27   , an embodiment of a frame  1100  is illustrated. The frame  1100  can include a frame body  1102 , an upper anchoring feature  1104 , and a lower anchoring feature  1106 . A longitudinal axis of the frame  1100  may be defined as the central axis that extends through the center of the frame  1100  between the upper and lower ends of the frame  1100 . Features of the frame  1100  can be incorporated in any of the prostheses described herein. 
     The frame body  1102  can include an upper region  1108 , an intermediate region  1110 , and a lower region  1112 . As shown, the frame body  1102  can include a plurality of struts with at least some of the struts forming cells  1114   a - b . The sides of cells  1114   a - b  can have a “bell-curve” shape. As shown in the illustrated embodiment, an upper portion of the first row of cells  1114   a  can be formed from circumferentially expansible struts  1116   a  and a lower portion of the first row of cells  1114   a  can be formed from circumferentially-expansible struts  1116   b . The upper portion of the second row of cells  1114   b  can be formed from circumferentially expansible struts  1116   b  and a lower portion of the second row of cells  1114   b  can be formed from circumferentially-expansible struts  1116   c . The frame body  1102  can include a plurality of interconnecting struts  1118   a - d . The struts  1118   a - d  can be straight segments extending in a circumferential direction about the longitudinal axis of the frame  1100 . These struts  1118   a - d  can form a flat upper end and lower end of the frame body  1102 . 
     The upper anchoring feature  1104  can be similar to upper anchoring feature  924  described in connection with prosthesis  900  illustrated in  FIGS.  20 - 22   . The upper anchoring feature  1104  can be formed from a row of circumferentially expansible struts  1120 . The circumferentially-expansible struts  1120  can be attached to the frame body  1102  via one or more struts  1122 . The struts  1122  can be attached to the frame body  1102  at struts  1118   b . However, it is to be understood that struts  1122  can extend from other portions of the frame body  1102 , such as the upper and/or uppermost ends of cells  1102 . The upper anchoring feature  1104  can include tips or ends  1124 . The tips or ends can include eyelets  1126  which can allow other components of a prosthesis to be attached thereto, such as a skirt. Moreover, the eyelets  1126  can allow the prosthesis to be coupled to a delivery system. 
     The lower anchoring feature  1106  can include one or more anchors  1128 . The anchors  1128  can include a strut  1130  and extend to a tip or end  1132 . The anchors  1128  can extend from above a lower end of a lower region  1112  of the frame body  1002 . For example, the anchors  1128  can extend downwardly and/or radially outwardly from struts  1118   c . The anchors  1128  can also extend upwardly towards the tip or end  1132 . As shown in the illustrated embodiment, at least a portion of the anchors  1016 , such as a segment  1130   b  of strut  1130  and the tip or end  1132 , can be curved and/or inclined in a circumferential direction about the longitudinal axis of the frame  1100 . For example, the strut  1130  can incorporate a bend about an axis perpendicular to and/or passing through the longitudinal axis of the frame  1100 . The bend can orient a second portion  1130   b  of the strut  1130  such that it is more inclined in a circumferential direction relative to the first portion  1130   a  of the strut  1130 . As shown, the second portion  1130   b  can be inclined at an angle of about 30 degrees with respect to a plane parallel to and/or passing through the longitudinal axis of the frame  1100 . In some embodiments, the second portion can be curved and/or inclined at an angle of between about 10 degrees to about 80 degrees relative to a plane parallel to and/or passing through the longitudinal axis of the frame  1100 , about 15 degrees to about 60 degrees relative to a plane parallel to and/or passing through the longitudinal axis of the frame  1100 , about 20 degrees to about 40 degrees relative to a plane parallel to and/or passing through the longitudinal axis of the frame  1100 , about 30 degrees relative to a plane parallel to and/or passing through the longitudinal axis of the frame  1100 , any sub-range within these ranges, and any other angle as desired. 
     Embodiments of Biased or Compressible Anchoring Features 
     In some embodiments, the prostheses described herein can incorporate a biased or compressible anchoring feature. The anchoring feature can be axially and/or radially biased or compressible. This can beneficially allow the anchoring feature to shift when subjected to forces, such as those which may be applied to an implanted anchoring feature during the cardiac cycle. This can significantly reduce the impact applied to tissue in contact with the anchor by spreading the applied force over a longer duration of time thereby reducing trauma to such tissue. In some embodiments, the biased or compressible anchoring features can be combined with cushions and/or covers described herein to further reduce trauma. 
     For example, tips or ends of an anchoring feature can be generally parallel to a longitudinal axis of the prosthesis and be in contact with a ventricular side of the native mitral valve annulus. Axial biasing or compression of such an anchoring feature can allow the anchoring feature to shift and apply the force over an extended duration of time to the ventricular side of the native mitral valve annulus. This can be particularly beneficial during systole in which the prosthesis is subject to a force tending to move the prosthesis towards the atrium. As another example, tips or ends of an anchoring feature can be generally perpendicular to a longitudinal axis of the prosthesis (e.g., a flange) and be in contact with an atrial side of the native mitral valve annulus. Radial biasing or compression of such an anchoring feature can allow the anchoring feature to shift and apply the force over an extended duration of time to the atrial side of the native mitral valve annulus. 
     Axial and/or radial biasing or compressibility can also the anchoring feature to better conform to tissue of the body cavity in which the anchoring feature is positioned. For example, similar to other prostheses described herein, the anchoring feature can include a plurality of individual anchors extending around a periphery of a frame. Each of the tips or ends of the anchors can independently shift to conform to the native anatomy, such as a native mitral annulus. 
     The axial and/or radially biasing or compressibility of the anchoring feature can also facilitate positioning within a delivery system. For example, the anchoring feature can shift to a position which better conforms to the shape of the delivery system, such as a sheath of the delivery system. As another example, the anchoring feature can radially compress to reduce the crimp profile of the anchoring feature. 
     It is to be understood that the biased or compressible anchoring features can be used in combination with other anchoring features described herein or as a replacement for one or more of the anchoring features described herein. 
     With reference to  FIG.  48   , an embodiment of a frame  2500  is illustrated. The frame  2500  can include a frame body  2502  and/or an anchoring feature  2504 . The anchoring feature  2504  can include a strut  2504   a  connected to the frame body  2502 . The strut  2504   a  can extend to a tip or end  2504   b . As shown, the tip or end  2504   b  can be formed from a plurality of wires. These wires may be looped to form a generally three-dimensional teardrop shape. The wires may be compliant such that the tip or end  2504   b  can be axially and/or radially biased or compressed. 
     With reference next to  FIG.  49   , an embodiment of a frame  2550  is illustrated. The frame  2550  can include a frame body  2552  and/or an anchoring feature  2554 . The anchoring feature  2554  can include a strut  2554   a  connected to the frame body  2552 . The strut  2554   a  can extend to a tip or end  2554   b . As shown, the tip or end  2554   b  can be formed from one or more wires. The one or more wires may be spiraled to form a generally three-dimensional conical shape. The wires may be compliant such that the tip or end  2554   b  can axially and/or radially biased or compressed. 
     With reference to  FIG.  50   , an embodiment of an anchoring feature  2600  is illustrated. The anchoring feature  2600  can include a strut  2602  which can be connected to a frame body (not shown). The strut  2602  can extend to a tip or end  2604 . As shown, the tip or end  2604  can have a serpentine shape. The serpentine shape can allow the tip or end  2604  to axially compress as represented by arrow  2606 . The serpentine shape can allow the tip or end  2604  to radially compress as represented by arrows  2608 . In some embodiments, the tip or end  2604  can be biased radially outward (e.g., out-of-plane movement). This can be achieved by forming the material of the tip or end  2604  out of a thinner or more compliant material. In some embodiments, such as the anchoring feature  2650  illustrated in  FIG.  51   , the anchoring feature can include multiple prongs  2654   a ,  2654   b  having a serpentine shape. 
     With reference to  FIG.  52   , an embodiment of an anchoring feature  2700  is illustrated. The anchoring feature  2700  can include a strut  2702  which can be connected to a frame body (not shown). The strut  2702  can extend to a tip or end  2704 . As shown, the tip or end  2704  can be formed from a plurality of cells. The cells can be foreshortening cells such as the illustrated diamond-shaped cells. The cells can allow the tip or end  2704  to axially compress as represented by arrow  2706 . The cells can allow the tip or end  2704  to radially compress as represented by arrows  2708 . In some embodiments, the tip or end  2704  can be biased radially outward (e.g., out-of-plane movement). This can be achieved by forming the material of the tip or end  2704  out of a thinner or more compliant material. 
     With reference to  FIG.  53   , an embodiment of an anchoring feature  2800  is illustrated. The anchoring feature  2800  can include a strut  2802  which can be connected to a frame body (not shown). The strut  2802  can extend to a tip or end  2804 . As shown, the tip or end  2804  can be formed from one or more prongs  2806   a ,  2806   a . The tip or end  2804  can include a component such as a plate  2808 . The plate  2808  can advantageously increase the surface area of the tip or end  2804  thereby reducing pressures applied to tissue. The plate  2808  can be flexible to allow the plate  2808  to deform when subjected to forces. In some embodiments, the plate  2808  can be retained in a collapsed configuration prior to delivery. For example, the plate  2808  may be retained in a collapsed configuration via a suture. The suture may be biodegradable such that the plate  2808  expands after implantation. 
     In some embodiments, the tips or ends can be covered with a biodegradable material. This can allow the tips or ends to be retained in a compressed configuration when initially implanted into a body cavity. Over time, the material can biodegrade and allow the tips or ends to expand into the shapes illustrated above. In some embodiments, the entire anchoring feature can be formed from a biodegradable or resorbable material. In some implementations, the entire anchoring features can be resorbed after a duration of time sufficient to allow tissue ingrowth around the prosthesis. In some embodiments, the anchoring features can be removable. It is to be understood that other geometries and structures can be implemented with respect to the anchoring features described herein. Further details on such geometries and structures can be found in U.S. Application No. 15/653,390, entitled REPLACEMENT HEART VALVE PROSTHESIS, filed on Jul. 18, 2017, the entirety of which has been incorporated herein by reference. 
     Other anchoring mechanisms are also contemplated. In some embodiments, the inner and/or outer frames can include one or more barbs to facilitate securement to tissue of a body cavity in which the prosthesis is positioned. In some embodiments, the inner and/or outer frames can include a tether which can be attached tissue of the body cavity. For example, the tether may be attached to a portion of the heart wall, such as an apex of the heart wall. 
     Exemplary Placement of Replacement Valves 
     Reference is now made to  FIG.  28 A -30 which illustrate schematic representations of an embodiment of a prosthesis  1200  in an expanded configuration, having an inner frame portion  1202  and an outer frame portion  1204 , positioned within a native mitral valve of a heart  10 . As noted above, in some embodiments the prostheses described herein can be positioned within a native mitral valve. A portion of the native mitral valve is shown schematically and represents typical anatomy, including a left atrium  20  positioned above an annulus  40  and a left ventricle  30  positioned below the annulus  40 . The left atrium  20  and left ventricle  30  communicate with one another through a mitral annulus  40 . Also shown schematically in  FIG.   28 A -30 is a native mitral leaflet  50  having chordae tendineae  60  that connect a downstream end of the mitral leaflet  50  to the papillary muscle of the left ventricle  30 . The portion of the prosthesis  1200  disposed upstream of the annulus  40  (toward the left atrium) can be referred to as being positioned supra-annularly. The portion generally within the annulus  40  can be referred to as positioned intra-annularly. The portion downstream of the annulus  40  can be referred to as being positioned sub-annularly (toward the left ventricle). In the illustrated embodiment, only a part of the foreshortening portion is positioned intra-annularly or sub-annularly, and the rest of the prosthesis  1200  is supra-annular. 
     As shown in the situations illustrated in  FIG.  28 A -30, the prosthesis  1200  can be disposed so that the mitral annulus  40  is between the upper or atrial anchoring feature  1210  and the lower or ventricular anchoring feature  1220  with a portion of the outer frame portion  1204  contacting the mitral annulus  40  along an inner edge or periphery. As shown in  FIG.  28 A -29, portions of the mitral annulus  40  and/or the mitral leaflet  50  can be positioned between the outer frame portion  1204  and the lower anchoring feature  1220 . The mitral annulus  40  and/or the mitral leaflet  50  can be pinched between the outer frame portion  1204  and the lower anchoring feature  1220 . As shown, the outer frame portion  1204  is oriented radially inward to conform to the shape of mitral annulus  40  and/or the mitral leaflet  50 . In an expanded configuration, the outer frame portion  1204  can be positioned radially outward in a natural, unbiased state. Accordingly, with the mitral annulus  40  and/or the mitral leaflet  50  positioned therebetween, the outer frame portion  1204  can be biased outward to apply a pinching force on the mitral annulus  40  and/or the mitral leaflet  50 . 
     In some situations, the prosthesis  1200  can be positioned such that ends or tips  1222  of the lower anchoring feature  1220  can contact the ventricular side of the annulus  40  as shown, for example, in  FIGS.  28 A-B . In some situations, the prosthesis  1200  can be positioned such that ends or tips  1222  of the lower anchoring feature  1220  do not contact the annulus  40  as shown, for example, in  FIG.  29   , and may just contact a downstream side of the leaflet  50 . In some situations, the prosthesis  1200  can be positioned such that the lower anchoring feature  1220  does not extend around the leaflet  50  as illustrated, but rather are positioned radially inward of the leaflet  50  as shown, for example, in  FIG.  30   . While  FIGS.  28 A- 30    are described separately below, it should be understood that one or more of the situations illustrated in  FIGS.  28 A- 30    may be present when the prosthesis  1200  is positioned at the implantation location, such as a native mitral valve. For example, in some situations the prosthesis  1200  may be positioned such that some portion of the anchoring feature  1220  may contact the annulus  40  while another portion of the lower anchoring feature  1220  may not. Moreover, it may be contemplated some in some situations, some portion of the anchoring feature  1220  may be positioned 
     With reference first to the situations illustrated in  FIGS.  28 A- 29   , the prosthesis  1200  can be positioned so that the ends or tips  1222  of the lower anchoring feature  1220  are on a ventricular side of the mitral annulus  40  and the ends or tips  1212  of the upper anchoring feature  1210  are on an atrial side of the mitral annulus  40 . The lower anchoring feature  1220  can be positioned such that the ends or tips  1222  of the lower anchoring feature  1220  are on a ventricular side of the native leaflets radially outwardly beyond a location where chordae tendineae  60  connect to free ends of the native leaflets  50 . The lower anchoring feature  1220  may extend between at least some of the chordae tendineae  60  and, in some situations such as those shown in  FIGS.  28 A-B , can contact or engage a ventricular side of the annulus  40 . It is also contemplated that in some situations, such as those shown in  FIG.  29   , the lower anchoring feature  1220  may not contact the annulus  40 , though the lower anchoring feature  1220  may still contact the native leaflet  50 . In some situations, the lower anchoring feature  1220  can contact tissue of the left ventricle  30  beyond the annulus  40  and/or a ventricular side of the leaflets  50 . 
     During delivery, the lower anchoring feature  1220  (along with the inner frame portion  1202  and outer frame portion  1204 ) can be moved toward the ventricular side of the annulus  40  with the lower anchoring feature  1220  extending between at least some of the chordae tendineae  60  to provide tension on the chordae tendineae  60  after the prosthesis  1200  is finally delivered. The degree of tension provided on the chordae tendineae  60  can differ. For example, little to no tension may be present in the chordae tendineae  60  as shown in  FIG.  28 B  where the leaflet  50  is shorter than or similar in size to the lower anchoring feature  1220 . A greater degree of tension may be present in the chordae tendineae  60  as shown in  FIG.  28 A  where the leaflet  50  is longer than the lower anchoring feature  1220  and, as such, takes on a compacted form and is pulled proximally. An even greater degree of tension may be present in the chordae tendineae  60  as shown in  FIG.  29    where the leaflets  50  are even longer relative to the lower anchoring feature  1220 . As shown in  FIG.  29   , the leaflet  50  is sufficiently long such that the lower anchoring feature  1220  does not contact the annulus  40 . 
     The upper anchoring feature  1210  can be positioned such that the ends or tips  1212  of the upper anchoring feature  1210  are on or adjacent the atrial side of the annulus  40  and/or tissue of the left atrium  20  beyond the annulus  40 . In some situations, some portion or all of the upper anchoring feature  1210  may only occasionally contact or engage atrial side of the annulus  40  and/or tissue of the left atrium  20  beyond the annulus  40 . For example, as shown in  FIGS.  28 A- 30   , the upper anchoring feature  1210  may be spaced from the atrial side of the annulus  40  and/or tissue of the left atrium  20  beyond the annulus  40 . The upper anchoring feature  1210  may be utilized to provide axial stability for the prosthesis  1200  and prevent off-axis orientation. Further, the upper anchoring feature  1210  can act as a safety feature without utilizing them for axial stability and off-axis orientation. For example, if the prosthesis  1200  is improperly deployed so that the prosthesis  1200  is deployed too low toward the left ventricle  30 , the upper anchoring feature  1210  can prevent the prosthesis  1200  from falling into the left ventricle  30 . It is to be understood that some or all of the upper anchoring feature  1210  may contact the atrial side of the annulus  40  and/or tissue of the left atrium  20  beyond the annulus  40 . 
     In some situations such as that shown in  FIG.  30   , the leaflet  50  may not be captured between the frame portions  1202 ,  1204  and a portion of the lower anchoring feature  1220 . As shown, the portion of the lower anchoring feature  1220  may be positioned along an atrial surface of the leaflet  50 . The portion of the lower anchoring feature  1220  may also be positioned along an inner surface of the annulus  40 . It is also contemplated that the portion of the lower anchoring feature  1220  may exert a force against the leaflet  50  such that the leaflet  50  is pushed radially outward, relative to the longitudinal axis of the frame  1202 , towards a wall of the heart  10 . In such situations, the outer frame portion  1204  can still anchor intra-annularly and/or along an atrial side of the leaflet  50 . In alternative situations (not shown), the outer frame portion  1204  can still anchor along a ventricular side of the annulus  40 . 
     As noted above, although the in vivo situations of  FIGS.  28 A- 30    have been described separately, it should be understood that one or more of these situations may be present when a prosthesis is positioned at the implantation location, such as a native mitral valve. For example, a portion of the lower anchoring feature  1220  may not capture the leaflet  50  whereas the remaining portion may capture the leaflet  50 . 
     Delivery of Prosthesis 
     The prostheses described herein can be delivered to a patient’s native heart valve in various ways, such as by open surgery, minimally-invasive surgery, and percutaneous or transcatheter delivery through the patient’s vasculature. In some embodiments, the prosthesis can be delivered to a patient’s native mitral valve through procedure such as, but not limited to, a transapical procedure and a transseptal procedure. As noted above, the prostheses can be used with a variety of delivery systems such as “slot”based and/or “tether”based systems. For purposes of  FIGS.  31  and  32   , it is to be understood that the distal direction is towards the right of the drawing. 
     With reference first to the system  1300  of  FIG.  31   , the system  1300  can include a delivery device  1310  with a prosthesis  1380  (illustrated schematically) contained within the delivery device  1310 . A first end  1382  of the prosthesis  1380  can be placed in a compressed state such that the first end  1382  of the prosthesis  1380  is retained between a nose cone  1320  and an inner retention member  1322  when the inner retention member  1322  is received within and covered by the nose cone  1320 . The inner retention member  1322  can include one or more slots which interface with locking tabs  1384 . The interface between the locking tabs  1384  and slots of the inner retention member  1322  can inhibit axial movement of the prosthesis  1380  relative to the inner retention member  1322 . When the first end  1382  of the prosthesis  1380  is uncovered, such as by moving the nose cone  1320  distally relative to the inner retention member  1322  or by moving the inner retention member  1322  proximally relative to the nose cone  1320 , the first end  1382  of the prosthesis  1380  can be released. This release can be caused by the prosthesis  1380  transitioning from a collapsed configuration to an expanded configuration when the prosthesis  1380  is formed from a self-expanding material. 
     At least a second end  1386  of the prosthesis  1380  can be placed in a compressed state such that the second end  1386  of the prosthesis  1380  is retained within a hollow shaft member  1330 . When the second end  1386  is uncovered, such as by moving the hollow shaft member  1330  proximally relative to the prosthesis  1380  or by moving the prosthesis  1380  distally relative to the hollow shaft member  1330 , the second end  1386  of the prosthesis  1380  can be released. This release can be caused by the prosthesis  1380  transitioning from a collapsed configuration to an expanded configuration when the prosthesis  1380  is formed from a self-expanding material. In some embodiments, the delivery system  1310  can include a tether  1340  which can wrap around a portion of the prosthesis  1380 , such as an anchoring feature on the second end  1386 . The tether  1340  can be used to control expansion of a portion of the prosthesis  1380 , such as the second end  1386 , when the portion of the prosthesis  1380  is uncovered. For example, in some embodiments, the tether  1340  can be used to control the rate at which anchors positioned at the second end  1386  flip from the collapsed configuration to the expanded configuration such that the anchors extend towards the first end  1382 . 
     In some embodiments, the system  1300  can be used in connection with a transapical procedure to access a native mitral valve. During such a procedure, the system  1300  can access a mitral valve through the apex of the heart. The anchoring feature on a ventricular side of the prosthesis  1380 , such as the second end  1386 , can be released on a ventricular side of the native mitral valve annulus. During delivery, the anchoring feature on a ventricular side of the annulus (along with the prosthesis 1380) can be moved toward the ventricular side of the annulus with the ventricular anchors extending between at least some of the chordae tendineae to provide tension on the chordae tendineae. The degree of tension provided on the chordae tendineae can differ. For example, little to no tension may be present in the chordae tendineae if the leaflet is shorter than or similar in size to the ventricular anchors. A greater degree of tension may be present in the chordae tendineae where the leaflet is longer than the ventricular anchors and, as such, takes on a compacted form and is pulled toward the native valve annulus. An even greater degree of tension may be present in the chordae tendineae where the leaflets are even longer relative to the ventricular anchors. The leaflet can be sufficiently long such that the ventricular anchors do not contact the annulus. After the anchoring feature on a ventricular side of the annulus is positioned, the remainder of the prosthesis  1380  can be deployed from the delivery system  1310 . 
     Reference is now made to  FIGS.  54 A- 54 H  which illustrate schematic representations of an embodiment of a prosthesis  2900  and a delivery system  2950  during various stages of deployment within a native mitral valve of a heart  10 . The prosthesis  2900  can include an inner frame  2910  and an outer frame  2920 . The inner frame  2910  can include an inner frame body  2912  and an inner frame anchoring feature  2914 . The prosthesis  2900  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein, such as prostheses  100 ,  200 ,  1500 ,  1600 . 
     The delivery system  2950  can include a nose cone  2960  and an inner retention member  2962  at a first end of the delivery system  2950 . The nose cone  2960  and inner retention member  2970  can retain an upper end of the prosthesis  2900 . The delivery system  2950  can include a hollow shaft member  2980  and a tether  2990 . The hollow shaft member  2980  can retain portions of the prosthesis  2900  therein. The tether  2990  can be tensioned to retain portions of the prosthesis  2900  in a collapsed state. The delivery system  2950  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other delivery systems described herein, such as delivery system  1310 . 
     With reference first to  FIG.  54 A , the prosthesis  2900  and delivery system  2950  can be introduced with the prosthesis  2900  in a fully collapsed configuration. As shown, the prosthesis  2900  and the delivery system  2950  can be introduced in a direction from the ventricle to the atrium (e.g., a transapical delivery procedure). 
     With reference next to  FIG.  54 B , the hollow shaft member  2980  can be retracted downwardly or proximally to expose the prosthesis  2900 . This can allow the inner frame anchoring feature  2914  to transition to an expanded configuration. In some instances, a portion of the outer frame  2920  can also expand. As shown, the nose cone  2960  can be sized to retain at least a portion, or the entirety, of an upper region of the prosthesis  2900  in a collapsed or crimped configuration. This can beneficially reduce radial expansion of the prosthesis  2900  during this step of delivery. As shown in the illustrated embodiment, the inner frame anchoring feature  2914  can be positioned generally above the annulus  40  prior to allowing the inner frame anchoring feature  2914  to expand; however, it is to be understood that this step can occur while the inner frame anchoring feature  2914  is positioned within the annulus  40 , below the annulus  40 , or below the leaflets  50 . Although the inner frame  2910  is shown in a fully collapsed configuration via tether  2990 , it is to be understood that the inner frame  2910  can at least partially expand during this stage. 
     With reference next to in  FIG.  54 C , the prosthesis  2900  can be moved such that the inner frame anchoring feature  2914  is positioned below the annulus  40 . As shown, the inner frame anchoring feature  2914  can be positioned below free edges of the leaflets  50 . With reference next to  FIG.  54 D , the tether  2990  can be loosened to allow the inner frame  2910  to expand further radially outward. In some embodiments, the nose cone  2960  can be advanced upwardly or proximally relative to the inner retention member  2970  to allow the inner frame  2910  and/or outer frame  2920  to expand further. The prosthesis  2900  may be moved during this process to seat the inner frame anchoring feature  2914  against the annulus  40 . 
     In some situations, a user may determine that the prosthesis  2900  should be repositioned. The prosthesis  2900  may be recaptured reversing the previous steps as shown in  FIG.  54 E . The inwardly tapered shape of the outer frame  2920  can facilitate the process of recapturing the device. For example, the inwardly tapered shape can function as a funnel which draws the outer frame  2920  and/or inner frame  2910  together when advancing the hollow shaft member  2980  over the outer frame  2920 . The user may then re-expand the prosthesis  2900  as shown in  FIG.  54 F . 
     With reference next to  FIG.  54 G , the prosthesis  2900  can be fully deployed by advancing the nose cone  2960  further upwardly or proximally relative to the inner retention member  2970 . As shown, the inner frame anchoring feature  2914  can be positioned between chordae tendineae  60  and contact a ventricular side of the annulus  40 . Moreover, the annulus  40  and/or leaflets  50  can be engaged between the inner frame anchoring feature  2914  and the outer frame  2920 . With reference next to  FIG.  54 H , the prosthesis  2900  is illustrated with the delivery system  2950  removed from the heart  10 . As shown, prosthesis  2900  includes one or more flexible valve leaflets  2930  (e.g., three leaflets) which allow blood to flow in a direction from the left atrium  20  to the left ventricle  30 . The inner frame  2910 , inner frame anchoring feature  2914 , and/or outer frame  2920  of prosthesis  2900  can be positioned similarly to the inner frame  3310 , inner frame anchoring feature  3314 , and/or outer frame  3320  of prosthesis  3300  shown in  FIG.  58   . 
     Reference is now made to  FIGS.  55 A- 55 H  which illustrate schematic representations of an embodiment of a prosthesis  3000  and a delivery system  3050  during various stages of deployment within a native mitral valve of a heart  10 . These steps can be similar to those described above in connection with  FIGS.  54 A- 54 F . The prosthesis  3000  can include an inner frame  3010  and an outer frame  3020 . The inner frame  3010  can include an inner frame body  3012  and an inner frame anchoring feature  3014 . The prosthesis  3000  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein, such as prostheses  1900 ,  2000 ,  2200 ,  2400 . 
     The delivery system  3050  can include a nose cone  3060  and an inner retention member  3062  at a first end of the delivery system  3050 . The delivery system  3050  can include a hollow shaft member  3080  and a tether  3090 . The delivery system  3050  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other delivery systems described herein, such as delivery system  1310 . 
     With reference first to  FIG.  55 A , the prosthesis  3000  and delivery system  3050  can be introduced with the prosthesis  3000  in a fully collapsed configuration. With reference next to  FIG.  55 B , the hollow shaft member  3080  can be retracted downwardly or proximally to expose the prosthesis  2900 . As shown in the illustrated embodiment, the inner frame anchoring feature  2914  can be positioned generally above the annulus  40  prior to allowing the inner frame anchoring feature  2914  to expand; however, it is to be understood that this step can occur while the inner frame anchoring feature  2914  is positioned within the annulus  40 , below the annulus  40 , or below the leaflets  50 . Although the inner frame  2910  is shown in a fully collapsed configuration via tether  2990 , it is to be understood that the inner frame  2910  can at least partially expand during this stage. 
     With reference next to in  FIG.  55 C , the prosthesis  3000  can be moved such that the inner frame anchoring feature  3014  is positioned below the annulus  40 . As shown, the inner frame anchoring feature  3014  can be positioned below free edges of the leaflets  50 . As shown in the illustrated embodiment, the geometry of the outer frame  3020  can advantageously increase a gap between the outer frame  3020  and the inner frame anchoring feature  3014 . This can facilitate positioning the prosthesis  3000  such that the leaflets  50  are positioned between the outer frame  3020  and the inner frame anchoring feature  3014 . 
     With reference next to  FIG.  55 D , the tether  3090  can be loosened to allow the inner frame  3010  to expand further radially outward. The prosthesis  3000  may be moved during this process to seat the inner frame anchoring feature  3014  against the annulus  40 . 
     In some situations, a user may determine that the prosthesis  3000  should be repositioned. The prosthesis  3000  may be recaptured reversing the previous steps as shown in  FIG.  55 E . The user may then re-expand the prosthesis  3000  as shown in  FIG.  55 F . With reference next to  FIG.  55 G , the prosthesis  3000  can be fully deployed by advancing the nose cone  3060  further upwardly or proximally relative to the inner retention member  3070 . With reference next to  FIG.  55 H , the prosthesis  3000  is illustrated with the delivery system  3050  removed from the heart  10 . As shown, prosthesis  3000  includes one or more flexible valve leaflets  3030  (e.g., three leaflets) which allow blood to flow in a direction from the left atrium  20  to the left ventricle  30 . The inner frame  3010 , inner frame anchoring feature  3014 , and/or outer frame  3020  of prosthesis  3000  can be positioned similarly to the inner frame  3410 , inner frame anchoring feature  3414 , and/or outer frame  3420  of prosthesis  3400  shown in  FIG.  59   . 
     With reference next to the system  1400  of  FIG.  32   , the system  1400  can include a delivery device  1410  with a prosthesis  1480  (illustrated schematically) contained within the delivery device  1410 . A first end  1482  of the prosthesis  1480  can be placed in a compressed state such that the first end  1482  of the prosthesis  1480  is retained between an inner retention member  1420  and another portion of the delivery device, such as an outer retention member  1422 , when the inner retention member  1420  is received within and covered by the outer retention member  1422 . The interface between the locking tabs  1484  and slots of the inner retention member  1420  can inhibit axial movement of the prosthesis  1480  relative to the inner retention member  1420 . When the first end  1482  of the prosthesis  1480  is uncovered, such as by moving the outer retention member  1422  proximally relative to the inner retention member  1420  or by moving the inner retention member  1420  distally relative to the outer retention member  1422 , the first end  1482  of the prosthesis  1480  can be released from the inner retention member  1422 . If the inner retention member  1420  is fully uncovered, the first end  1482  of the prosthesis  1480  can be released from the delivery device  1410 . This release can be caused by the prosthesis  1480  transitioning from a collapsed configuration to an expanded configuration when the prosthesis  1480  is formed from a self-expanding material. 
     At least a second end  1486  of the prosthesis  1480  can be placed in a compressed state such that the second end  1486  of the prosthesis  1480  is retained within an outer sheath assembly  1430 . When the second end  1486  is uncovered, such as by moving the outer sheath assembly  1430  proximally relative to the prosthesis  1480  or by moving the prosthesis  1480  distally relative to the outer sheath assembly  1430 , the second end  1486  of the prosthesis  1480  can be released. This release can be caused by the prosthesis  1480  transitioning from a collapsed configuration to an expanded configuration when the prosthesis  1480  is formed from a self-expanding material. In some embodiments, anchors positioned at the second end  1486  can flip from the collapsed configuration to the expanded configuration such that they extend towards the first end  1482 . 
     In some embodiments, the system  1400  can be used in connection with a transseptal procedure to access a native mitral valve. During such a procedure, the system  1400  can access a mitral valve through a septal puncture. The anchoring feature on a ventricular side of the prosthesis  1480 , such as the second end  1486 , can be released on a ventricular side of the native mitral valve annulus. During delivery, the anchoring feature on a ventricular side of the annulus (along with the prosthesis 1480) can be moved toward the ventricular side of the annulus with the ventricular anchors extending between at least some of the chordae tendineae to provide tension on the chordae tendineae. The degree of tension provided on the chordae tendineae can differ. For example, little to no tension may be present in the chordae tendineae if the leaflet is shorter than or similar in size to the ventricular anchors. A greater degree of tension may be present in the chordae tendineae where the leaflet is longer than the ventricular anchors and, as such, takes on a compacted form and is pulled toward the native valve annulus. An even greater degree of tension may be present in the chordae tendineae where the leaflets are even longer relative to the ventricular anchors. The leaflet can be sufficiently long such that the ventricular anchors do not contact the annulus. After the anchoring feature on a ventricular side of the annulus is positioned, the remainder of the prosthesis  1480  can be deployed from the delivery device  1410 . 
     Reference is now made to  FIGS.  56 A- 56 H  which illustrate schematic representations of an embodiment of a prosthesis  3100  and a delivery system  3150  during various stages of deployment within a native mitral valve of a heart  10 . The prosthesis  3100  can include an inner frame  3110  and an outer frame  3120 . The inner frame  3110  can include an inner frame body  3112  and an inner frame anchoring feature  3114 . The prosthesis  3100  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein, such as prostheses  100 ,  200 ,  1500 ,  1600 . 
     The delivery system  3150  can include an inner retention member  3160  and a sheath  3170 . The inner retention member  3160  and sheath  3170  can retain an upper end of the prosthesis  3100 . The delivery system  3150  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other delivery systems described herein, such as delivery system  1410 . 
     With reference first to  FIG.  56 A , the prosthesis  3100  and delivery system  3150  can be introduced with the prosthesis  3100  in a fully collapsed configuration. As shown, the prosthesis  3100  and the delivery system  3150  can be introduced in a direction from the atrium to the ventricle (e.g., a transseptal delivery procedure). 
     With reference next to  FIG.  56 B , the sheath  3170  can be retracted upwardly or proximally to expose the prosthesis  3100 . This can allow the inner frame anchoring feature  3114  to transition to an expanded configuration. As shown in the illustrated embodiment, the inner frame anchoring feature  3114  can be positioned generally above the annulus  40  prior to allowing the inner frame anchoring feature  3114  to expand; however, it is to be understood that this step can occur while the inner frame anchoring feature  3114  is positioned within the annulus  40 , below the annulus  40 , or below the leaflets  50 . 
     With reference next to in  FIG.  56 C , the prosthesis  3100  can be moved such that the inner frame anchoring feature  3114  is positioned below the annulus  40 . As shown, the inner frame anchoring feature  3114  can be positioned below free edges of the leaflets  50 . With reference next to  FIG.  56 D , the sheath  3170  can be further retracted to allow the inner frame  3110  and/or outer frame  3120  to expand further radially outward. The prosthesis  3100  may be moved during this process to seat the inner frame anchoring feature  3114  against the annulus  40 . 
     In some situations, a user may determine that the prosthesis  3100  should be repositioned. The prosthesis  3100  may be recaptured reversing the previous steps as shown in  FIG.  56 E . The inwardly tapered shape of the outer frame  3120  can facilitate the process of recapturing the device. For example, the inwardly tapered shape can function as a funnel which draws the outer frame  3120  and/or inner frame  3110  together when advancing the sheath  3170  over the outer frame  3120 . The user may then re-expand the prosthesis  3100  as shown in  FIG.  56 F . 
     With reference next to  FIG.  56 G , the prosthesis  3100  can be fully deployed by further retracting the sheath  3170 . As shown, the inner frame anchoring feature  3114  can be positioned between chordae tendineae  60  and contact a ventricular side of the annulus  40 . Moreover, the annulus  40  and/or leaflets  50  can be engaged between the inner frame anchoring feature  3114  and the outer frame  3120 . With reference next to  FIG.  56 H , the prosthesis  3100  is illustrated with the delivery system  3150  removed from the heart  10 . As shown, prosthesis  3100  includes one or more flexible valve leaflets  3130  (e.g., three leaflets) which allow blood to flow in a direction from the left atrium  20  to the left ventricle  30 . The inner frame  3110 , inner frame anchoring feature  3114 , and/or outer frame  3120  of prosthesis  3100  can be positioned similarly to the inner frame  3310 , inner frame anchoring feature  3314 , and/or outer frame  3320  of prosthesis  3300  shown in  FIG.  58   . 
     Reference is now made to  FIGS.  57 A- 57 F  which illustrate schematic representations of an embodiment of a prosthesis  3200  and a delivery system  3250  during various stages of deployment within a native mitral valve of a heart  10 . These steps can be similar to those described above in connection with  FIGS.  56 A- 56 F . The prosthesis  3200  can include an inner frame  3210  and an outer frame  3220 . The inner frame  3210  can include an inner frame body  3212  and an inner frame anchoring feature  3214 . The prosthesis  3200  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other prostheses described herein, such as prostheses  1900 ,  2000 ,  2200 ,  2400 . 
     The delivery system  3250  can include an inner retention member  3260  and a sheath  3270 . The delivery system  3250  can share characteristics, such as structure and/or functionality, which are the same as, or at least similar to, those of other delivery systems described herein, such as delivery system  1310 . 
     With reference first to  FIG.  57 A , the prosthesis  3200  and delivery system  3250  can be introduced with the prosthesis  3200  in a fully collapsed configuration. With reference next to  FIG.  57 B , the sheath  3270  can be retracted upwardly or proximally to expose the prosthesis  3200 . As shown in the illustrated embodiment, the inner frame anchoring feature  3214  can be positioned generally above the annulus  40  prior to allowing the inner frame anchoring feature  3214  to expand; however, it is to be understood that this step can occur while the inner frame anchoring feature  3214  is positioned within the annulus  40 , below the annulus  40 , or below the leaflets  50 . 
     With reference next to in  FIG.  57 C , the prosthesis  3200  can be moved such that the inner frame anchoring feature  3214  is positioned below the annulus  40 . With reference next to  FIG.  55 D , the sheath  3270  can be further retracted to allow the inner frame  3210  and/or outer frame  3220  to expand further radially outward. The prosthesis  3200  may be moved during this process to seat the inner frame anchoring feature  3214  against the annulus  40 . As shown, the inner frame anchoring feature  3214  can be positioned below free edges of the leaflets  50 . As shown in the illustrated embodiment, the geometry of the outer frame  3220  can advantageously increase a gap between the outer frame  3220  and the inner frame anchoring feature  3214 . This can facilitate positioning the prosthesis  3200  such that the leaflets  50  are positioned between the outer frame  3220  and the inner frame anchoring feature  3214 . 
     In some situations, a user may determine that the prosthesis  3200  should be repositioned. The prosthesis  3200  may be recaptured reversing the previous steps as shown in  FIG.  57 E . The user may then re-expand the prosthesis  3200  as shown in  FIG.  57 F . With reference next to  FIG.  57 G , the prosthesis  3200  can be fully deployed by further retracting the sheath  3170 . With reference next to  FIG.  57 H , the prosthesis  3200  is illustrated with the delivery system  3250  removed from the heart  10 . As shown, prosthesis  3200  includes one or more flexible valve leaflets  3230  which allow blood to flow in a direction from the left atrium  20  to the left ventricle  30 . The inner frame  3210 , inner frame anchoring feature  3214 , and/or outer frame  3220  of prosthesis  3200  can be positioned similarly to the inner frame  3410 , inner frame anchoring feature  3414 , and/or outer frame  3420  of prosthesis  3400  shown in  FIG.  59   . 
     Other Embodiments 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the disclosure. Accordingly, the scope of the present disclosure is defined only by reference to the claims presented herein or as presented in the future. 
     Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination. 
     For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment. 
     Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z. 
     Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree. 
     The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.