Patent Publication Number: US-2022226106-A1

Title: Systems and methods for heart valve therapy

Description:
TECHNICAL FIELD 
     This document relates to prosthetic heart valves, such as prosthetic mitral valves that can be implanted using transcatheter techniques. This document also relates to systems and methods for implanting composite prosthetic mitral valves having an inner valve portion that is affixed to an outer anchor portion. 
     BACKGROUND 
     The long-term clinical effect of valve regurgitation is recognized as a significant contributor to cardiovascular related morbidity and mortality. Thus, for many therapies intended to treat the mitral valve, one primary goal is to significantly reduce or eliminate regurgitation. By eliminating the regurgitation at the mitral valve, the destructive volume overload effects on the left ventricle can be attenuated. The volume overload of mitral regurgitation (MR) relates to the excessive kinetic energy required during isotonic contraction to generate overall stroke volume in an attempt to maintain forward stroke volume and cardiac output. It also relates to the pressure potential energy dissipation of the leaking valve during the most energy-consuming portion of the cardiac cycle, isovolumetric contraction. Additionally, therapies for MR reduction can have the effect of reducing the elevated pressures in the left atrium and pulmonary vasculature reducing pulmonary edema (congestion) and shortness of breath symptomatology. Such therapies for MR reduction may also have a positive effect on the filling profile of the left ventricle (LV) and the restrictive LV physiology that can result with MR. These pathophysiologic issues indicate the potential benefits of MR therapy, but also indicate the complexity of the system and the need for a therapy to focus beyond the MR level or grade. 
     In some percutaneous access procedures in which a medical device is introduced through a patient&#39;s skin and into a patient&#39;s blood vessel, such an access can be used to introduce devices into the patient without the use of large cut downs, which can be painful and in some cases can hemorrhage or become infected. A percutaneous access generally employs only a small hole through the skin, which subsequently seals relatively easily, and heals quickly in comparison to a surgical cut down. 
     SUMMARY 
     This document describes prosthetic heart valves, such as prosthetic mitral valves, that interface and anchor in cooperation with the anatomical structures of a native mitral valve. For example, this document describes a composite two-portion prosthetic heart valve in which two expandable components are attached to each other and arranged in a nested configuration during both the transcatheter delivery process and the deployment process within the heart. In addition, systems and methods for implanting such composite two-portion prosthetic heart valves are described herein. 
     In one aspect, this disclosure is directed to a prosthetic mitral valve for a heart. The prosthetic mitral valve includes a valve assembly comprising an expandable valve frame and an occluder attached to the expandable valve frame, and an anchor assembly comprising an expandable anchor frame. The valve assembly is disposed within an interior space defined by the anchor assembly. 
     Such a prosthetic mitral valve may optionally include one or more of the following features. In some embodiments, the expandable valve frame includes three atrial leaflet arches disposed on a proximal end portion of the expandable valve frame. In particular embodiments, the expandable anchor frame includes three anchor arches disposed on a proximal end portion of the expandable anchor frame. In certain embodiments, each atrial leaflet arch of the three atrial leaflet arches is affixed to a respective anchor arch of the three anchor arches. 
     In another aspect, this disclosure is directed to a prosthetic mitral valve that includes: (i) a valve assembly comprising an expandable valve frame and an occluder attached to the expandable valve frame, the expandable valve frame comprising three atrial leaflet arches disposed on a proximal end portion of the expandable valve frame; and (ii) an anchor assembly comprising an expandable anchor frame, the expandable anchor frame comprising three anchor arches disposed on a proximal end portion of the expandable anchor frame. The valve assembly is disposed within an interior space defined by the anchor assembly. Each atrial leaflet arch of the three atrial leaflet arches is affixed to a respective anchor arch of the three anchor arches. 
     Such a prosthetic mitral valve may optionally include one or more of the following features. An apex portion of each atrial leaflet arch of the three atrial leaflet arches may be affixed to an apex portion of the respective anchor arch of the three anchor arches. An entirety of each atrial leaflet arch of the three atrial leaflet arches may be affixed to an entirety of the respective anchor arch of the three anchor arches. The expandable anchor frame may also include a plurality of arched atrial holding features. In some embodiments, while the expandable anchor frame is in an expanded configuration, each arched atrial holding feature of the plurality of arched atrial holding features extends transversely outward in relation to a longitudinal axis defined by the anchor assembly. The plurality of arched atrial holding features may include three arched atrial holding features. Each arched atrial holding feature of the three arched atrial holding features may be aligned with a corresponding atrial leaflet arch of the three atrial leaflet arches and with a corresponding atrial leaflet arch of the three atrial leaflet arches. In some embodiments, while the prosthetic mitral valve is coupled to a native mitral valve, each arched atrial holding feature of the plurality of arched atrial holding features is positioned directly adjacent to, or spaced apart just superior to, an annulus of the native mitral valve. The expandable anchor frame may also include: (a) a hub; (b) a first elongate element extending from the hub, the first elongate element including a first sub-annular foot; (c) a second elongate element extending from the hub, the second elongate element including a second sub-annular foot; (d) a third elongate element extending from the first elongate element, the third elongate element including a third sub-annular foot; and (e) a fourth elongate element extending from the second elongate element, the fourth elongate element including a fourth sub-annular foot. In some embodiments, while the anchor assembly is coupled to a native mitral valve, each of the first foot, the second foot, the third foot, and the fourth foot are positioned within a sub-annular gutter of the native mitral valve. The hub may be located at a distal end of the expandable anchor frame and may be threaded for releasable attachment with a delivery device. The expandable anchor frame may also include a systolic anterior motion containment member that is configured to be at least partially disposed behind an anterior leaflet of the native mitral valve while the anchor assembly is coupled to the native mitral valve. 
     In another aspect, this disclosure is directed to a prosthetic mitral valve that includes: (1) a valve assembly comprising an expandable valve frame and an occluder attached to the expandable valve frame, the expandable valve frame being expandable from a compressed nested configuration during transcatheter delivery to a deployed configuration at a native mitral heart valve site; and (2) an anchor assembly comprising an expandable anchor frame. The expandable anchor frame being expandable from a compressed delivery configuration during transcatheter delivery to an anchored configuration at a native mitral heart valve site. The expandable valve frame of the valve assembly is nested within the expandable anchor frame anchor while the expandable anchor frame is in the compressed delivery configuration for transcatheter delivery. 
     In another aspect, this disclosure is directed to a transcatheter mitral valve replacement system for a heart, that includes: (i) a delivery sheath having a distal end portion insertable into a left atrium; (ii) a delivery catheter slidably disposed within the delivery sheath; and (iii) a composite two-portion prosthetic mitral valve coupled to the delivery catheter by one or more control wires. The composite two-portion prosthetic mitral valve is configured to be disposed within the delivery sheath in a radially compressed condition and to radially self-expand when the composite two-portion prosthetic mitral valve is outside of the delivery sheath and is unconstrained by the one or more control wires. The composite two-portion prosthetic mitral valve includes: (a) a valve assembly including an expandable valve frame and a tri-leaflet occluder, the expandable valve frame comprising three atrial leaflet arches disposed on a proximal end portion of the expandable valve frame; and (b) an anchor assembly comprising an expandable anchor frame that defines an interior space within which the valve assembly is nested. The expandable anchor frame comprising three anchor arches disposed on a proximal end portion of the expandable anchor frame. Each atrial leaflet arch of the three atrial leaflet arches is affixed to a respective anchor arch of the three anchor arches. 
     Such a transcatheter mitral valve replacement system may optionally include one or more of the following features. The system may also include a pusher catheter slidably disposed within the deliver catheter and releasably coupled to the anchor assembly. The one or more control wires may include: a first control wire coupled to proximal end portions of the anchor assembly and the valve assembly; a second control wire coupled to a mid-body portion of the anchor assembly; and a third control wire coupled to a distal end portion of the valve assembly. The one or more control wires comprises a total of two control wires consisting of: a first control wire coupled to proximal end portions of the anchor assembly and the valve assembly; and a second control wire coupled to a distal end portion of the valve assembly. The one or more control wires comprises a total of two control wires consisting of: a first control wire coupled to proximal end portions of the anchor assembly and the valve assembly; and a second control wire coupled to a mid-body portion of the anchor assembly. 
     In another aspect, this disclosure is directed to a method for deploying a transcatheter prosthetic mitral valve system within a native mitral valve of a patient. The method includes: (a) navigating a delivery sheath within a vasculature of the patient such that a distal end portion of the delivery sheath is positioned within a left atrium of the patient, the delivery sheath containing a composite two-portion prosthetic mitral valve in a radially compressed condition. The composite two-portion prosthetic mitral valve includes: (i) a valve assembly including an expandable valve frame and a tri-leaflet occluder, the expandable valve frame comprising three atrial leaflet arches disposed on a proximal end portion of the expandable valve frame; and (ii) an anchor assembly comprising an expandable anchor frame that defines an interior space within which the valve assembly is nested, the expandable anchor frame comprising three anchor arches disposed on a proximal end portion of the expandable anchor frame. Each atrial leaflet arch of the three atrial leaflet arches is affixed to a respective anchor arch of the three anchor arches. The method for deploying a transcatheter prosthetic mitral valve system within a native mitral valve of a patient further includes: (b) expressing, in the left atrium, the composite two-portion prosthetic mitral valve, wherein a delivery catheter is releasably engaged with the composite two-portion prosthetic mitral valve using one or more control wires, the valve assembly remaining disposed within the interior space defined by the anchor assembly during and after the expressing; (b) engaging the anchor assembly with the native mitral valve, wherein the anchor assembly is in a radially expanded condition while engaged with the native mitral valve; and (c) after the engaging the anchor assembly in the radially expanded condition, expanding a distal end portion of the expandable valve frame within the interior space. 
     In some embodiments of the method for deploying a transcatheter prosthetic mitral valve system within a native mitral valve of a patient, the engaging the anchor assembly with the native mitral valve includes positioning atrial holding features of the anchor assembly adjacent to supra-annular tissue surfaces above an annulus of the mitral valve. 
     In another aspect, this disclosure is directed to a prosthetic mitral valve that includes: (1) a valve assembly comprising a plurality of atrial leaflet arches disposed on a proximal end portion of the valve assembly and one or more valve leaflets; and (2) an anchor assembly comprising a plurality of anchor arches disposed on a proximal end portion of the anchor assembly. The valve assembly is disposed within an interior space defined by the anchor assembly. Each atrial leaflet arch of the plurality of atrial leaflet arches is affixed to a respective anchor arch of the plurality of anchor arches. 
     In another aspect, this disclosure is directed to a prosthetic mitral valve that includes: a valve assembly comprising a plurality of valve leaflets; and an anchor assembly. The valve assembly is disposed within an interior space defined by the anchor assembly. A proximal end of the valve assembly is affixed to a proximal end of the anchor assembly. 
     Some or all of the embodiments described herein may provide one or more of the following advantages. First, using the devices, systems, and methods in accordance with particular implementations described herein, various medical conditions, such as heart valve conditions, can be treated in a minimally invasive fashion. Such minimally invasive techniques can tend to reduce recovery times, patient discomfort, and treatment costs. 
     Second, some implementations of the devices, systems, and methods described herein facilitate the implantation of a composite two-portion prosthetic heart valve in which two expandable components are attached and arranged in a nested configuration during the transcatheter delivery and deployment processes. Accordingly, the time to complete the procedure is advantageously minimalized. This can result in reduced time in the operating room, lessened patient risks, and lower procedural costs. 
     Third, the transcatheter prosthetic heart valve and deployment systems described herein can be configured to facilitate accurate control of the prosthetic valve components during the delivery and deployment process. In some embodiments, one or more control wires are coupled to end portions or middle portions of the prosthetic valve components in a manner that allows for isolated, accurate movements of each degree of freedom associated with the catheters and prosthetic valve components. Accordingly, relatively complex catheter and/or valve component movements are facilitated in an accurately controllable and user-convenient manner. In result, transcatheter implant procedures can be performed with enhanced patient safety and treatment efficacy using the devices, systems, and methods described herein. 
     Fourth, some embodiments of the prosthetic mitral valve and deployment systems described herein can be used in a completely percutaneous/transcatheter mitral replacement procedure that is streamlined, safe, reliable, and repeatable by surgeons and/or interventional cardiologists of a variety of different skill levels. 
     Fifth, in particular embodiments, the composite two-portion prosthetic mitral valves can optionally include two different expandable components (e.g., an anchor assembly and a valve assembly) that are delivered to the implantation site in an attached and nested arrangement. For example, the first component (e.g., the anchor assembly including a first expandable frame) can be configured to engage with the heart tissue that is at or proximate to the annulus of the native mitral valve, and the second component (e.g., the valve assembly including a second expandable frame) can be configured to provide a seal interface with native valve leaflets of the mitral valve. 
     Sixth, by using particular implementations of the composite two-portion prosthetic heart valves that are attached and arranged in a nested configuration during the transcatheter delivery and deployment processes, patients can be treated while guarding the patients&#39; hemodynamic stability during the implantation process. Such devices and techniques can tend to reduce the need for ancillary interventions, such as the need for installing a balloon pump and the like. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a perspective view of a patient on an operating table undergoing a percutaneous deployment of an implantable prosthetic heart valve in accordance with some embodiments. 
         FIG. 2  shows a commissural cross-sectional view of a human heart (from the left side of the heart) with a composite two-portion prosthetic valve assembly deployed within a native mitral valve of the heart. 
         FIG. 3  is an exploded posterior side view of the two-portion prosthetic valve assembly of  FIG. 2 , showing an example anchor assembly and an example valve assembly, in accordance with some embodiments. As described further herein, portions of the anchor assembly and the valve assembly are actually attached to each other in the embodiments described herein. 
         FIG. 4  is a simplified, schematic representation of the two-portion prosthetic valve assembly of  FIG. 2 , including the anchor assembly and the valve assembly depicted in an example attached configuration. 
         FIG. 5  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve in a nested arrangement as in  FIG. 4  and after the composite two-portion valve has emerged from a delivery sheath. Three control wires are included in this example. 
         FIG. 6  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 5 , with the anchor assembly partially expanded and positioned partially within the annulus of a native heart valve. 
         FIG. 7  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 6 , with the anchor assembly expanded farther than in  FIG. 6  such that the anchor feet are positioned within a sub-annular gutter of the native valve. 
         FIG. 8  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 7 , with the anchor assembly fully expanded such that the atrial holding features are supra-annularly adjacent to the native valve tissue. 
         FIG. 9  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 8 , with the control wires that effect the anchor assembly removed. 
         FIG. 10  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve in a nested arrangement and after the composite two-portion valve has emerged from a delivery sheath. An arrangement of two control wires are included in this example. 
         FIG. 11  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve in a nested arrangement and after the composite two-portion valve has emerged from a delivery sheath. Another arrangement of two control wires are included in this example. 
         FIG. 12  is a simplified, schematic representation of the two-portion prosthetic valve assembly of  FIG. 2 , including the anchor assembly and the valve assembly depicted in another example attached configuration. 
         FIG. 13  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve as in  FIG. 12  in a nested arrangement and after the composite two-portion valve has emerged from a delivery sheath. Three control wires are included in this example. 
         FIG. 14  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 13 , with the anchor assembly partially expanded and positioned partially within the annulus of a native heart valve. 
         FIG. 15  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 14 , with the anchor assembly expanded farther than in  FIG. 14  such that the anchor feet are positioned within a sub-annular gutter of the native valve. 
         FIG. 16  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 15 , with the anchor assembly fully expanded such that the atrial holding features are supra-annularly adjacent to the native valve tissue. 
         FIG. 17  schematically depicts the nested composite two-portion prosthetic valve as in  FIG. 16 , with the control wires that effect the anchor assembly removed. 
         FIG. 18  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve in a nested arrangement and after the composite two-portion valve has emerged from a delivery sheath. An arrangement of two control wires are included in this example. 
         FIG. 19  schematically depicts the anchor assembly and the valve assembly of the composite two-portion prosthetic valve in a nested arrangement and after the composite two-portion valve has emerged from a delivery sheath. Another arrangement of two control wires are included in this example. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Referring to  FIGS. 1-3 , in some medical procedures, a two-portion prosthetic mitral valve  400  can be deployed in a patient  1  using a transcatheter delivery system  100 . The two-portion prosthetic mitral valve  400  is configured to anchor in cooperation with the anatomical structures of a native mitral valve  17 , and to serve as a functional replacement for the native mitral valve  17  of the patient  1 . 
     In some embodiments, the two-portion prosthetic mitral valve  400  comprises two separate portions, an anchor assembly portion  200  and a valve assembly portion  300 , that can be made to mechanically engage in a releasably mated configuration with each other in situ. In particular embodiments, however, the two-portion prosthetic mitral valve  400  is a single composite structure that includes an anchor assembly portion  200  and a concomitant, conjoined valve assembly portion  300  that are permanently attached to each other. This disclosure is primarily directed to the latter. That is, this disclosure is primarily directed to embodiments of two-portion prosthetic mitral valves  400  that are single composite structures in which at least portions of the anchor assembly portion  200  and the valve assembly portion  300  are permanently conjoined, attached, and/or affixed to each other. 
     In some implementations, the two-portion prosthetic mitral valve  400  is percutaneously deployed via a femoral or iliac vein through a groin opening/incision  2  in the patient  1  in a minimally invasive fashion. In particular implementations, a deployment control system  6  is used to initiate and/or control the movements of various components of the transcatheter delivery system  100 , and of the two-portion prosthetic mitral valve  400 . 
     The two-portion prosthetic mitral valve  400  can be delivered to and implanted in the heart  10  using a percutaneous, or minimally invasive, technique via the venous or arterial system (without open-chest or open-heart surgery). In some implementations, the transcatheter delivery system  100  and two-portion prosthetic mitral valve  400  are used in conjunction with one or more imaging modalities such as x-ray fluoroscopy, echocardiography, magnetic resonance imaging, computed tomography (CT), and the like. Accordingly, various components of the transcatheter delivery system  100  and/or the two-portion prosthetic mitral valve  400  can include one or more features to enhance their visibilities under imaging modalities, such as radio-opaque markers. 
     Early steps of the process for deploying the two-portion prosthetic mitral valve  400  includes the placement of a guidewire within the vasculature and heart  10  of the patient  1 . In the depicted implementation, the guidewire is installed into the heart  10  prior to the other components of the delivery system  100 . In some embodiments, the guidewire is made of materials such as, but not limited to, nitinol, stainless steel, high-tensile-strength stainless steel, and the like, and combinations thereof. The guidewire  11  may include various tip designs (e.g., J-tip, straight tip, etc.), tapers, coatings, covers, radiopaque (RO) markers, and other features. In some embodiments, the guidewire has one or more portions with differing lateral stiffnesses, column strengths, lubricity, and/or other physical properties in comparison to other portions of the guidewire. 
     In some implementations, the guidewire is percutaneously inserted into a femoral vein of the patient  1 . The guidewire is routed to the inferior vena cava and into the right atrium. After creating an opening in the atrial septum (e.g., a trans-septal puncture of the fossa ovalis or other portion of the atrial septum), the guidewire is routed into the left atrium  16 . Lastly, the guidewire is routed through the native mitral valve  17  and into the left ventricle  18 . This is preferably performed without entangling the guidewire with the chordae tendineae  40  of the native mitral valve  17 . In some implementations, the guidewire can be installed into the heart  10  along other anatomical pathways. The guidewire thereafter serves as a rail over which other components of the delivery system  100  are passed. 
     The transcatheter delivery system  100  facilitates implantation of the two-portion prosthetic mitral valve  400  in the heart  10  while the heart  10  is beating. Using interventional cardiology techniques, the transcatheter prosthetic heart valve delivery system  100  can be navigated through the venous vasculature of the patient  1 , and through the atrial septum (e.g., a trans-septal puncture of the fossa ovalis or other portion of the atrial septum), to obtain access to the left atrium  16  of the patient&#39;s heart  10 .  FIG. 2  shows the two-portion prosthetic mitral valve  400  fully deployed within the native mitral valve such that the prosthetic mitral valve  400  is performing the mitral valve function. 
     In  FIG. 3 , the anchor assembly portion  200  and the valve assembly portion  300  are shown separately from each other so that structures and features of each portion are visually distinguishable. However, the actual two-portion prosthetic mitral valve  400 , as described herein, are single composite structures in which the anchor assembly portion  200  and the valve assembly portion  300  are permanently conjoined, attached, and/or affixed to each other. 
     In the depicted embodiment, the anchor assembly portion  200  includes four anchor feet: a lateral anterior foot  220   a , a lateral posterior foot  220   b , a medial posterior foot  220   c , and a medial anterior foot  220   d . In some embodiments, fewer or more anchor feet may be included (e.g., two, three, five, six, or more than six). In some embodiments, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  are portions of the anchor assembly portion  200  that are configured for contact with a sub-annular gutter  19  of the native mitral valve  17 , without penetrating tissue of the native mitral valve  17 . Accordingly, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  have atraumatic surfaces that are generally comparable to feet. However, in some embodiments one or more of the anchor feet  220   a ,  220   b ,  220   c , and  220   d  are configured to penetrate tissue and may have anchor features such as barbs, coils, hooks, and the like. 
     It should be understood that the depicted anchor assembly portion  200  is merely one non-limiting example of the anchor assemblies included within the scope of this disclosure. 
     In some embodiments, the anchor assembly portion  200  includes supra-annular structures and sub-annular structures (in reference to the positions of those structures in relation to the annulus of the native mitral valve  17  when the two-portion prosthetic mitral valve  400  is implanted at the site of the native mitral valve  17 ). For example, in some embodiments the sub-annular structures of the anchor assembly portion  200  can include the aforementioned anchor feet  220   a ,  220   b ,  220   c , and  220   d , a systolic anterior motion (SAM) containment member  212 , and a hub  210 . The SAM containment member  212  is designed to inhibit the incursion of an anterior leaflet of the native mitral valve  17  into the left ventricular outflow tract (LVOT) during systole, which might otherwise cause LVOT obstruction or the creation of high LVOT pressure gradients. In some embodiments, the hub  210  functions as a connection structure for the delivery system  100 . In addition, the hub  210  can function as a stabilizing structural component from which a lateral anterior sub-annular support arm  230   a  and a medial anterior sub-annular support arm  230   d  extend to the anchor feet  220   a  and  220   d  respectively. In some embodiments, a lateral posterior sub-annular support arm  230   b  extends from the lateral anterior sub-annular support arm  230   a  to the lateral posterior foot  220   b . In some embodiments, a medial posterior sub-annular support arm  230   c  extends from the medial anterior sub-annular support arm  230   d  to the medial posterior foot  220   c . In particular embodiments, no hub  210  is included. 
     In the depicted embodiment, the supra-annular structures of the anchor assembly portion  200  include: a lateral anterior atrial holding feature  240   a , a posterior atrial holding feature  240   b , and a medial anterior atrial holding feature  240   c ; a lateral anterior anchor arch  250   a , a posterior anchor arch  250   b , and a medial anterior anchor arch  250   c . The atrial holding features  240   a ,  240   b , and  240   c  are configured to contact the shelf-like supra-annular atrial tissue surface superior to the mitral valve annulus, and to thereby stabilize the two-portion prosthetic mitral valve  400  in supra-annular areas and to provide migration resistance in the inferior direction toward the left ventricle  18 . 
     The lateral anterior anchor arch  250   a , the posterior anchor arch  250   b , and the medial anterior anchor arch  250   c  are joined with each other, or unitary with each other, to form an undulating supra-annular ring  250  that acts as a supra-annular structural element to which the valve assembly portion  300  can be affixed. 
     The valve assembly portion  300  includes a proximal end portion  302  and a distal end portion  303 . When the two-portion prosthetic mitral valve  400  is implanted in a native mitral valve  17 , the proximal end portion  302  is located supra-annularly (in the left atrium  16 , superior to the annulus of the native mitral valve  17 ) and the distal end portion  303  is located sub-annular (in the left ventricle  18 , interior to the annulus of the native mitral valve  17 ). The proximal end portion  302  defines the generally circular valvular entrance orifice of the valve assembly portion  300 . At least three prosthetic valve leaflets (not visible) are located within the valve assembly portion  300 . 
     In the depicted embodiment, the proximal end portion  302  of the valve assembly portion  300  includes three atrial leaflet arches  310   a ,  310   b , and  310   c  that together define an undulating ring  310  at the proximal end portion  302  of the valve assembly portion  300 . The undulating ring  310  formed by the three atrial leaflet arches  310   a ,  310   b , and  310   c  generally corresponds to the undulating supra-annular ring  250  of the anchor assembly portion  200 . Accordingly, as described further below, the anchor assembly portion  200  and the valve assembly portion  300  can be conjoined and/or affixed to each other at particular locations of, or entirely along, the adjacent interfacing portions of the supra-annular ring  250  and the undulating ring  310  of three atrial leaflet arches  310   a ,  310   b , and  310   c . In some embodiments, the supra-annular ring  250  of the anchor assembly portion  200  and the undulating ring  310  of the valve assembly portion  300  (or portions thereof) are unitarily formed as a single, shared element (rather than being a conjoined two-piece construct). 
     In some embodiments, each of the leaflet arches  310   a ,  310   b , and  310   c  includes an apex having one or more holes  312   a ,  312   b , and  312   c  respectively. In some embodiments, the holes  312   a ,  312   b , and  312   c  are used for coupling the proximal end of the valve assembly portion  300  to a delivery catheter using a proximal control wire. In some embodiments, one or more of the holes  312   a ,  312   b , and  312   c  are used for containing radiopaque material. 
     In the depicted embodiment, the valve assembly portion  300  generally flares outward along a distal direction. Said differently, the distal end portion  303  is flared outward in comparison to the proximal end portion  302 . Accordingly, the proximal end portion  302  defines a smaller outer profile in comparison to the distal end portion  303 . However, some regions of the distal end portion  303  bow inwardly. Such inward bowing can serve to mitigate LVOT obstructions and enhance sealing in some cases. 
     In some embodiments, the periphery of the distal end portion  303  is generally D-shaped in cross-section. The D-shaped periphery of the distal end portion  303  provides the valve assembly portion  300  with an advantageous outer profile for interfacing and sealing with the native mitral valve  17 . For example, in some implementations sealing is attained by coaptation between the D-shaped periphery of the distal end portion  303  and the leaflets of the native mitral valve  17 . 
     In some embodiments, such as the depicted embodiment, valve assembly portion  300  includes three leaflets (not visible) that perform the occluding function of the prosthetic mitral valve  400 . The cusps of the three leaflets are fixed to the three atrial leaflet arches  310   a ,  310   b , and  310   c , and to three commissural posts (not visible) that each extend distally from the intersections of the three leaflet arches  310   a ,  310   b , and  310   c . In some embodiments, the three commissural posts are disposed at about 120° apart from each other. The commissural posts each have a series of holes that can be used for attachment of the prosthetic valve leaflets, such as by suturing. The three leaflet arches  310   a ,  310   b , and  310   c  and the three commissural posts are areas on the valve assembly portion  300  to which the three prosthetic valve leaflets become attached to comprise a tri-leaflet occluder. As such, the valve assembly portion  300  provides a proven and advantageous frame configuration for the tri-leaflet occluder. When implanted in the native mitral valve  17 , the tri-leaflet occluder of the valve assembly portion  300  provides open flow during diastole and occlusion of flow during systole. The free edges of the three leaflets can seal by coaptation with each other during systole and open during diastole. 
     The three leaflets can be comprised of natural or synthetic materials. For example, the three leaflets can be comprised of any of the materials described below in reference to the coverings  270  and/or  340 , including the natural tissues such as, but not limited to, bovine, porcine, ovine, or equine pericardium. In some such embodiments, the tissues are chemically cross-linked using glutaraldehyde, formaldehyde, or triglycidyl amine solution, or other suitable crosslinking agents. In some embodiments, the leaflets have a thickness in a range of about 0.005″ to about 0.020″ (about 0.13 mm to about 0.51 mm), or about 0.008″ to about 0.012″ (about 0.20 mm to about 0.31 mm). In some embodiments, the leaflets have a thickness that is less than about 0.005″ (about 0.13 mm) or greater than about 0.020″ (about 0.51 mm). 
     In some embodiments, the occluding function of the two-portion prosthetic mitral valve  400  can be performed using configurations other than a tri-leaflet occluder. For example, bi-leaflet, quad-leaflet, or mechanical valve constructs can be used in some embodiments. 
     As shown in  FIG. 3 , in some embodiments the anchor assembly portion  200  includes a covering material  270  disposed on one or more portions of the anchor assembly portion  200  and/or the valve assembly portion  300  includes a covering material  340  disposed on one or more portion of the valve assembly portion  300 . The covering materials  270 / 340  can provide various benefits. For example, in some implementations the covering materials  270 / 340  can facilitate tissue ingrowth and/or endothelialization, thereby enhancing the migration resistance of the anchor assembly portion  200  and/or valve assembly portion  300 , and preventing thrombus formation on blood contact elements. In another example, as described further below, the covering materials  270 / 340  can be used to facilitate coupling between the anchor assembly portion  200  and the valve assembly portion  300  that is received therein. The cover materials  270 / 340  also prevent or minimizes abrasion and/or fretting between the anchor assembly portion  200  and valve assembly portion  300  to enhance durability. The covering materials  270 / 340  are omitted in  FIG. 2  to provide enhanced visualization of the interface between the anchor assembly portion  200  and valve assembly portion  300  with the native mitral valve  17 . 
     In some embodiments, the covering materials  270 / 340 , or portions thereof, comprises a fluoropolymer, such as an expanded polytetrafluoroethylene (ePTFE) polymer. In some embodiments, the covering materials  270 / 340 , or portions thereof, comprises a polyester, a silicone, a urethane, ELAST-EON™ (a silicone and urethane polymer), another biocompatible polymer, DACRON®, polyethylene terephthalate (PET), copolymers, or combinations and subcombinations thereof. In some embodiments, the covering materials  270 / 340 , or portions thereof, comprises a biological tissue. For example, in some embodiments the covering materials  270 / 340  can include natural tissues such as, but not limited to, bovine, porcine, ovine, or equine pericardium. In some such embodiments, the tissues are chemically treated using glutaraldehyde, formaldehyde, or triglycidylamine (TGA) solutions, or other suitable tissue crosslinking agents. 
     In some embodiments, the anchor arches  250   a ,  250   b , and  250   c  can include one or more covering-material cut-outs  252   a ,  252   b , and  252   c  respectively. In some embodiments, the valve assembly portion  300  can include a fabric portion  314   a  (and fabric portions  314   b  and  314   b ; not visible) that are physically disposed within the covering-material cut-outs  252   a ,  252   b , and  252   c  while the two-portion prosthetic mitral valve  400  is in its expanded configuration. 
     In some embodiments, the expandable frame structure of the anchor assembly portion  200  and/or the expandable frame structure of the valve assembly portion  300  are formed from a single piece of precursor material (e.g., sheet or tube) that is cut and expanded (and then connected to the hub  210  in the case of the anchor assembly  200 ). For example, some embodiments are fabricated from a tube that is laser-cut (or machined, chemically etched, water-jet cut, etc.) and then expanded and heat-set into its final expanded size and shape. In some embodiments, the expandable frame structure of the anchor assembly portion  200  is created compositely from multiple elongate members (e.g., wires or cut members) that are joined together with the hub  210  and each other to form the anchor assembly  200 . 
     In some embodiments, the anchor assembly portion  200  and the valve assembly portion  300  can be conjoined or affixed to each other at particular locations of, or entirely along, the adjacent interfacing portions of the supra-annular ring  250  and the three atrial leaflet arches  310   a ,  310   b , and  310   c  (undulating ring  310 ). For example, in some embodiments, solely discrete localized portions at the corresponding apices, or valleys, of the supra-annular ring  250  and the undulating ring  310  are attached/affixed to each other. Joining techniques such as, but not limited to, suturing, welding, using mechanical clips, lashing, and the like, and combinations thereof, can be used to attach/affix the supra-annular ring  250  and the undulating ring  310  (or discrete localized portions thereof) together. In certain embodiments, the apical portions and additional discrete localized portions along the adjacent interfacing supra-annular ring  250  and undulating ring  310  are attached/affixed to each other using such joining techniques. In particular embodiments, the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other along the entire lengths thereof. 
     As an alternative to using the aforementioned joining techniques, in some embodiments, the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  can be cut from a single piece of precursor material such that the frame structures are a unitary frame structure that comprises the frame structures of both the anchor assembly portion  200  and the valve assembly portion  300 . In such a case, the supra-annular ring  250  and the three atrial leaflet arches  310   a ,  310   b , and  310   c  (or particular portions thereof) are same physical elements (rather than being a conjoined two-piece construct that are attached/affixed to each other). 
     The expandable frame structures of the anchor assembly portion  200  and the valve assembly portion  300  can comprise various materials and combinations of materials. In some embodiments, nitinol (NiTi) is used as the material of the elongate members of the expandable frame structure of the anchor assembly portion  200  and/or the valve assembly portion  300 , but other materials such as stainless steel, L605 steel, polymers, MP35N steel, stainless steels, titanium, cobalt/chromium alloy, polymeric materials, Pyhnox, Elgiloy, or any other appropriate biocompatible material, and combinations thereof can be used. The super-elastic properties of NiTi make it a particularly good candidate material for the elongate members of the expandable frame structure of the anchor assembly portion  200  and/or the valve assembly portion  300  because, for example, NiTi can be heat-set into a desired shape. That is, NiTi can be heat-set so that the anchor assembly portion  200  and/or the valve assembly portion  300  tends to self-expand into a desired shape when the anchor assembly portion  200  and/or the valve assembly portion  300  is unconstrained, such as when the anchor assembly portion  200  and/or the valve assembly portion  300  is deployed out from the anchor delivery sheath  130 . An expandable frame structure of the anchor assembly portion  200  and/or the valve assembly portion  300  made of NiTi, for example, may have a spring nature that allows the anchor assembly portion  200  and/or the valve assembly portion  300  to be elastically collapsed or “crushed” to a low-profile delivery configuration and then to self-expand to the expanded configuration. The anchor assembly portion  200  and/or the valve assembly portion  300  may be generally conformable, fatigue resistant, and elastic to conform to the topography of the surrounding tissue when the anchor assembly portion  200  and/or the valve assembly portion  300  is deployed in the native mitral valve  17  of the patient  1 . 
     Still referring to  FIGS. 1-3 , the anchor feet  220   a ,  220   b ,  220   c , and  220   d  are sized and shaped to abut against the sub-annular gutter  19  of the native mitral valve  17 . In some embodiments, the anterior feet  220   a  and  220   d  are spaced apart from each other by a distance in a range of about 30 mm to about 45 mm, or about 20 mm to about 35 mm, or about 40 mm to about 55 mm. In some embodiments, the posterior feet  220   b  and  220   c  are spaced apart from each other by a distance in a range of about 20 mm to about 30 mm, or about 10 mm to about 25 mm, or about 25 mm to about 40 mm. 
     In some embodiments, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  have a height ranging from about 8 mm to about 12 mm, or more than about 12 mm. In some embodiments, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  have a gutter engaging surface area (when fabric covered) ranging from about 6 mm 2  to about 24 mm 2 . In some embodiments, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  each have essentially the same gutter engaging surface area. In particular embodiments, one or more of the anchor feet  220   a ,  220   b ,  220   c , and  220   d  has a different gutter engaging surface area than one or more of the other anchor feet  220   a ,  220   b ,  220   c , and  220   d . The anchor feet  220   a ,  220   b ,  220   c , and  220   d  can have widths ranging within about 1.5 mm to about 4.0 mm or more, and lengths ranging within about 3 mm to about 6 mm or more. The anchor feet  220   a ,  220   b ,  220   c , and  220   d  are sized and shaped so that the anchor assembly portion  200  does not significantly impair the natural function of mitral valve chordae tendineae  40 , the native mitral valve leaflets, and papillary muscles even after the anchor assembly portion  200  is anchored at the mitral valve site. 
     Referring to  FIG. 4 , an example two-portion prosthetic mitral valve  400  is schematically depicted (e.g., shown here in a view corresponding to  FIG. 2 ) to make the structures and the transcatheter deployment technique described below easier to visualize and understand. As described above, the two-portion prosthetic mitral valve  400  includes the anchor assembly portion  200  (including the hub  210 ) and the valve assembly portion  300 . The valve assembly portion  300  is positioned within the interior space of the anchor assembly portion  200 . In this figure (and in  FIGS. 5-19 ), the anchor assembly portion  200  is schematically shown in solid lines, while the valve assembly portion  300  is schematically shown in dashed lines for illustrative purposes. Those different line types (solid lines and dashed lines) are being used solely to help the viewer clearly distinguish the anchor assembly portion  200  from the valve assembly portion  300 . The use of the solid lines and dashed lines in this figure (and in  FIGS. 5-19 ) is provided for clarity of viewing of the two assemblies  200  and  300 , but the use of the dashed lines in this figure (and in  FIGS. 5-19 ) does not necessarily mean the elements shown in dashed lines are hidden or concealed from view. 
     In the depicted example embodiment of the two-portion prosthetic mitral valve  400 , discrete localized portions of the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other (rather than being attached/affixed to each other along the entire lengths thereof). In particular, in the depicted embodiment localized portions of the apices of the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other (while no other portions thereof are attached/affixed). The attachment can be created using joining techniques as described above, or by forming the frame structures of the supra-annular ring  250  and undulating ring  310  from a common piece of precursor material such that the respective local apical portions are made of shared unitary material (e.g., the same portion of material acting as the apices of each of the supra-annular ring  250  and undulating ring  310 ). 
     Referring also to  FIG. 5 , in some implementations the valve assembly portion  300  is positioned within the anchor assembly portion  200  during the transcatheter delivery and deployment processes of the two-portion prosthetic mitral valve  400  to the site of a native mitral valve. As described above, in the depicted embodiment the two devices (e.g., the anchor assembly portion  200  and the valve assembly portion  300 ) have different frame structures that are only attached/affixed to one another at localized portions of the three apices of the supra-annular ring  250  and undulating ring  310 . The two-portion prosthetic mitral valve  400  is arranged during delivery and deployment with the anchor assembly portion  200  laterally surrounding the valve assembly portion  300  so that when they are radially expanded in situ, additional portions of the anchor assembly portion  200  and the valve assembly portion  300  will become mechanically mated together. 
     In some implementations, a sheath  120  (which is a part of the transcatheter delivery system  100 ) can be used to simultaneously deliver the anchor assembly portion  200  and the valve assembly portion  300  to the heart  10 . That is, the anchor assembly portion  200  and the valve assembly portion  300  can be elastically collapsed to reduced diameters and constrained within the confines of the low-profile sheath  120 . In that arrangement, the sheath  120  (containing the anchor assembly portion  200  and the valve assembly portion  300  in radially collapsed configurations) can be navigated through the patient&#39;s vasculature and heart to arrive at the target location (e.g., within the heart proximate to the patient&#39;s native mitral valve). There, the anchor assembly portion  200  and the valve assembly portion  300  can be expressed out of the sheath  120 .  FIG. 5  depicts the anchor assembly portion  200  and the valve assembly portion  300  after having been expressed from the sheath  120 . As shown in this embodiment, the valve assembly portion  300  is nested within the anchor assembly  200  and portions of the three apices of the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other. 
     In some embodiments the sheath  120  has an outer diameter of about 28 Fr (about 9.3 mm), or about 30 Fr (about 10.0 mm). In some embodiments, the sheath  120  has an outer diameter in the range of about 26 Fr to about 34 Fr (about 8.7 mm to about 11.3 mm). In some embodiments, the sheath  120  has an outer diameter in the range of about 20 Fr to about 28 Fr (about 6.7 mm to about 9.3 mm). 
     The transcatheter delivery system  100  can also include a delivery catheter  140 . As described further below, the anchor assembly portion  200  and the valve assembly portion  300  can be attached to the delivery catheter  140  using one or more control wires. The delivery catheter  140  and the control wires can thereby be manipulated by a clinician to control the positioning of the anchor assembly portion  200  and the valve assembly portion  300  relative to the sheath  120 . For example, the delivery catheter  140  can be pushed distally while the sheath  120  is held stationary to make the anchor assembly portion  200  and the valve assembly portion  300  emerge from within the sheath  120 . Or, the sheath  120  can be pulled proximally while the delivery catheter  140  is held stationary to make the anchor assembly portion  200  and the valve assembly portion  300  emerge from within the sheath  120 . 
     The transcatheter delivery system  100  can also include an inner catheter  160  (also referred to herein as a “pusher catheter  160 ”). In some implementations, the inner catheter  160  is releasably coupled with the hub  210  of the anchor assembly  200 . For example, in some embodiments an externally threaded distal end portion of the inner catheter  160  can be threadedly coupled with an internally threaded hole defined by the hub  210 . When the nested anchor assembly portion  200  and valve assembly portion  300  are expressed from the sheath  120 , the inner catheter  160  can be moved (e.g., pushed distally) or held stationary in concert with the delivery catheter  140 . 
     In some embodiments, components of the transcatheter delivery system  100  (such as the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160 ) can include one or more of the following features. In some embodiments, one or more portions of the components of the transcatheter delivery system  100  are steerable (also referred to herein as “deflectable”). Using such steering, the transcatheter delivery system  100  can be deflected to navigate the patient&#39;s anatomy and/or to be positioned in relation to the patient&#39;s anatomy as desired. For example, the sheath  120  can be angled within the right atrium  12  to navigate the sheath  120  from the inferior vena cava  11  to the atrial septum. Accordingly, in some embodiments the sheath  120  may include at least one deflectable zone. Using a device such as the deployment control system  6  ( FIG. 1 ) a clinician can controllably deflect the deflection zone of the sheath  120  (and/or other components of the transcatheter delivery system  100 ) as desired. In some embodiments, one or more components of the transcatheter delivery system  100  can include one or more portions that have differing properties as compared to other portions of the component. For example, a component such as the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160  may have a portion that has greater flexibility, stiffness, column strength, and/or the like as compared to other portions of that same component. 
     In some embodiments, the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160  can comprise a tubular polymeric or metallic material. For example, in some embodiments the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160  can be made from polymeric materials such as, but not limited to, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), HYTREL®, nylon, PICOFLEX®, PEBAX®, TECOFLEX®, and the like, and combinations thereof. In alternative embodiments, the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160  can be made from metallic materials such as, but not limited to, nitinol, stainless steel, stainless steel alloys, titanium, titanium alloys, and the like, and combinations thereof. In some embodiments, the sheath  120 , the delivery catheter  140 , and/or the inner catheter  160  can be made from combinations of such polymeric and metallic materials (e.g., polymer layers with metal braid, coil reinforcement, stiffening members, and the like, and combinations thereof). 
     As stated above, in some embodiments one or more control wires can be used to releasably couple the anchor assembly portion  200  and the valve assembly portion  300  to the delivery catheter  140 . Such control wires can also be used by a clinician to control the radial expansion of the anchor assembly portion  200  and the valve assembly portion  300 —in some optional implementations, to control the radial expansion of the anchor assembly portion  200  independently from the radial expansion of the valve assembly portion  300  during the deployment procedure. For example, when a control wire is slackened (tension is relaxed) the associated anchor assembly portion  200  or valve assembly portion  300  will be allowed to radially self-expand. Conversely, when a control wire is tensioned, the associated anchor assembly portion  200  or valve assembly portion  300  will be radially contracted, compressed, or constrained. The control wires may also be thought of as “lassos” because, like a lasso, the control wires function to circumferentially, radially, or diametrically control/constrain the anchor assembly portion  200  and the valve assembly portion  300 . 
     Still referring to  FIG. 5 , control wires (e.g., control wires  142 ,  144 , and  148  as described further below) can be releasably coupled around one or more regions of the anchor assembly portion  200  and/or the valve assembly portion  300 . For example, control wires can be coupled to a proximal end region, one or more mid-body regions, and/or a distal end region of the anchor assembly portion  200  and/or the valve assembly portion  300 . In some cases, a single control wire can be coupled to both the anchor assembly portion  200  and the valve assembly portion  300 . In one such example, a single control wire can be coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300 . Tensioning the single control wire that is coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  will cause the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  to be concurrently radially contracted and constrained. Releasing tension from the single control wire that is coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  will allow the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  to concurrently radially expand. 
     In some cases, a single control wire is coupled to only one of either the anchor assembly portion  200  or the valve assembly portion  300 . In some such cases, a first control wire can be coupled to one region of either the anchor assembly portion  200  or the valve assembly portion  300 , and a second control wire can be coupled to another region of same anchor assembly portion  200  or valve assembly portion  300 . 
     In the depicted embodiment, the anchor assembly portion  200  and the valve assembly portion  300  are jointly configured to be releasably coupled with a proximal end control wire  142  at one or more proximal end coupling sites  254  that are located at, or adjacent to, the three apices of the supra-annular ring  250  and undulating ring  310 . In addition, the anchor assembly portion  200  is configured to be releasably coupled with a mid-body region control wire  148  at one or more anchor assembly mid-body coupling sites  256 . In addition, the valve assembly portion  300  is configured to be releasably coupled with a distal end region control wire  144  at one or more valve assembly distal end coupling sites  326 . 
     The control wire coupling sites (e.g., the proximal end coupling sites  254 , the anchor assembly mid-body coupling sites  256 , and the valve assembly distal end coupling sites  326 ) can be various types of structures to which a wire can be releasably coupled. For example, in some embodiments the control wire coupling sites can be a loop of suture material, two loops of suture material, or three or more loops of suture material. In some embodiments, the control wire coupling sites can be a structure defining an eyelet formed by, or attached to, the framework of the anchor assembly portion  200  and/or the valve assembly portion  300 . In some embodiments, the control wire coupling sites can be cells or struts of the framework of the anchor assembly portion  200  and/or the valve assembly portion  300 . Other types of suitable control wire coupling sites can also be used. 
     In the depicted embodiment, the valve assembly portion  300  is coupled to the delivery catheter  140  by: (i) the proximal end control wire  142  and (ii) the valve assembly distal end control wire  144 . The proximal end control wire  142  can be releasably coupled with the proximal end coupling sites  254 . The valve assembly distal end control wire  144  can be releasably coupled with the valve assembly distal end coupling sites  326 . 
     In the depicted embodiment, the anchor assembly portion  200  is coupled to the delivery catheter  140  by: (i) the proximal end control wire  142  and (ii) the anchor assembly mid-body control wire  148 . The proximal end control wire  142  can be releasably coupled with the proximal end coupling sites  254 . The anchor assembly mid-body control wire  148  can be releasably coupled with the anchor assembly mid-body coupling sites  256 . 
     In some implementations, a deployment control handle/system (such as the deployment frame system  6  of  FIG. 1 ) is used to control the movements of the control wires, and by extension, the movements of the corresponding anchor assembly portion  200  and/or valve assembly portion  300  to which the control wires are coupled. For example, the tension of the control wires can be increased or decreased to thereby allow radial self-expansion, or to thereby cause radial contraction/constriction, of the corresponding anchor assembly portion  200  or valve assembly portion  300 . 
     In some embodiments, the control wires extend through lumens defined in the wall of a catheter, such as the delivery catheter  140 . The control wires can extend from such lumens through luminal orifices at the end of the catheter, or at non-end luminal orifice locations along the catheter. For example, in the depicted embodiment, the valve assembly distal end control wire  144  extends from luminal orifices at the end of the delivery catheter  140 . However, the proximal end control wire  142  and the anchor assembly mid-body control wire  148  each extend from non-end luminal orifices located along the delivery catheter  140 . 
     In some embodiments, such as the depicted embodiment, individual control wires form a loop at the end of the catheter (e.g., the delivery catheter  140 ). That is, the control wire exits from a first luminal orifice of the catheter, then loops through one or more attachment sites of the anchor assembly portion  200  and/or the valve assembly portion  300 , then reenters a second luminal orifice of the catheter. Portions of the control wire are slidably positioned within lumens within the wall of the catheter. The two terminal ends of the control wire can be positioned at the user control mechanism (e.g., the deployment frame system  6  of  FIG. 1 ). To remove a control wire from engagement with the anchor assembly portion  200  and/or the valve assembly portion  300 , a clinician can simply pull on one end of the control wire while allowing the second end of the control wire to freely pass into the catheter wall lumen. As the clinician continues to pull, the entire control wire can be removed from engagement with the anchor assembly portion  200  and/or the valve assembly portion  300 , and even from within the lumens of the catheter (if so desired). 
       FIGS. 6-9  schematically depict an example serial process for deploying the anchor assembly portion  200  and the valve assembly portion  300  (collectively the two-portion prosthetic mitral valve  400  as described above in reference to  FIG. 4 ) in a native heart valve  17 . 
     It should be understood that retrieval of the anchor assembly portion  200  and the valve assembly portion  300  can be readily performed at any time during the depicted sequential procedures as long as at least one of the control wires remains coupled to the anchor assembly portion  200  and/or valve assembly portion  300 . For example, as long as the proximal end control wire  142  is coupled with the proximal ends of the anchor assembly portion  200  and the valve assembly portion  300 , retrieval can be performed, for example, using the following procedure. The anchor assembly mid-body control wire  148  can be released and/or removed from engagement with the anchor assembly  200 . Then, the valve assembly distal end control wire  144  can be tensioned to collapse the distal end of the valve assembly portion  300 . Next, the proximal end control wire  142  that is shared by the proximal ends of the anchor assembly portion  200  and the valve assembly portion  300  can be tensioned to collapse the proximal end of the anchor assembly portion  200  and the valve assembly portion  300  such that retrieval features (e.g., hooks, clips, slots, etc.) on the delivery catheter  140  become engaged with the framework of the anchor assembly portion  200  and/or valve assembly portion  300 . Next, the anchor assembly portion  200  and the valve assembly portion  300  can be retracted into sheath  120  (e.g., by pulling the delivery catheter  140  proximally in relation to the sheath  120 ). The retrieval features on the delivery catheter  140  (with which the anchor assembly portion  200  and/or the valve assembly portion  300  are engaged) and the tensioned valve assembly distal end control wire  144  facilitate the insertion of the valve assembly portion  300  (along with the delivery catheter  140 ) into the sheath  120 . 
     Referring to  FIG. 6 , as described above the transcatheter delivery system  100  can be been used to intravascularly navigate the two-portion prosthetic mitral valve  400  to the left atrium  16 . The anchor assembly portion  200  and the valve assembly portion  300  (positioned relative to each other in the nested arrangement as shown by virtue of the frame structures that are attached/affixed to one another at localized portions of the three apices of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 4 ) can be simultaneously expressed from the sheath  120  while in the left atrium  16 . In some implementations, it is desirable to orient (e.g., laterally pivot, pan, steer, etc.) the nested anchor assembly portion  200  and valve assembly portion  300  within the atrium  16  so that their longitudinal axes are generally perpendicular to the native mitral valve  17 , and coaxial with the native mitral valve  17  (e.g., to center the nested anchor assembly portion  200  with the line of coaptation of the native mitral valve  17 ). Such orienting of the partially or fully expanded anchor assembly portion  200  and valve assembly portion  300  within the atrium  16  may be advantageous versus having to orient them while they are still constrained within the delivery sheath  120 , as the latter assembly can be a relatively large and stiff catheter assembly. 
     After the two-portion prosthetic mitral valve  400  is expressed from the sheath  120  in the left atrium  16 , a clinician can relax some tension from the anchor assembly mid-body control wire  148  to allow the anchor assembly portion  200  to partially expand. For example, in some cases the mid-body region of the anchor assembly portion  200  may be allowed to expand about 75% of its fully expanded radial size. Accordingly, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  ( FIG. 3 ) expand radially outward. Such expansion can be performed in preparation for seating the anchor feet  220   a ,  220   b ,  220   c , and  220   d  within the sub-annular gutter  19  of the native mitral valve  17 . At this stage, the other control wires (e.g., the proximal end control wire  142  and the valve assembly distal end control wire  144 ) can remain fully tensioned such that the proximal end regions of the two-portion prosthetic mitral valve  400  and the entirety of the valve assembly  200  remain radially contracted. 
     With the mid-body region of the anchor assembly portion  200  partially expanded, the nested anchor assembly portion  200  and valve assembly portion  300  can be pushed distally (inferiorly toward the left ventricle  18 ) as indicated by arrow  50 . The anchor feet  220   a ,  220   b ,  220   c , and  220   d  may physically help to proper align the anchor assembly portion  200  (and the two-portion prosthetic mitral valve  400  as a whole) to the native mitral valve  17  as the anchor assembly portion  200  is partially pushed through the annulus of the native mitral valve  17 . The distal portions of the nested anchor assembly portion  200  and valve assembly portion  300  will pass through the annulus of the native mitral valve  17  and into the left ventricle  18  as shown. With the anchor assembly portion  200  partially radially contracted in a desired orientation, and appropriately aligned with the native mitral valve  17 , the anchor assembly portion  200  can be safely passed through the native mitral valve  17  without damaging the native mitral valve  17  and/or entangling chordae tendineae of the native mitral valve  17 . 
     Referring to  FIG. 7 , further distal movement of the two-portion prosthetic mitral valve  400  (the nested anchor assembly portion  200  and valve assembly portion  300 ) will cause the anchor feet  220   a ,  220   b ,  220   c , and  220   d  ( FIG. 3 ) to pass through the annulus of the native mitral valve  17  and into the left ventricle  18 . Then, the clinician can fully relax (or nearly fully relax) the tension from the anchor assembly mid-body control wire  148  to allow the mid-body region of the anchor assembly portion  200  to fully expand (or nearly fully expand). Accordingly, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  can be then properly seated within the sub-annular gutter  19  of the native mitral valve  17 . 
     The regions at or near the high collagen annular trigones of the sub-annular gutter  19  can generally be relied upon to provide strong, stable anchoring locations. The muscle tissue in the regions at or near the trigones also provides a good tissue ingrowth substrate for added stability and migration resistance of the anchor assembly  200 . Therefore, the regions at or near the trigones define a left anterior anchor zone and a right anterior anchor zone. The left anterior anchor zone and the right anterior anchor zone provide advantageous target locations for placement of the lateral anterior foot  220   a  and the medial anterior foot  220   d  respectively. The left posterior anchor zone and the right anterior anchor zone of the sub-annular gutter  19  can receive the lateral posterior foot  220   b  and the medial posterior foot  220   c  respectively. 
     Referring to  FIG. 8 , as a next step of the process for implanting the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another at localized portions of the three apices of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 4 ), the clinician can relax the proximal end control wire  142 . Doing so will allow the proximal end of the anchor assembly portion  200  (including the supra-annular structures of the anchor assembly portion  200 ) and the proximal end of the valve assembly portion  300  to self-expand. For example (referring also to  FIG. 3 ), relaxing the tension on the proximal end control wire  142  will allow radial expansion of the atrial holding features  240   a ,  240   b , and  240   c . The atrial holding features  240   a ,  240   b , and  240   c  are configured to contact the shelf-like supra-annular atrial tissue surface that is superior to the annulus of the native mitral valve  17 , and to thereby stabilize the anchor assembly portion  200  (and the two-portion prosthetic mitral valve  400  as a whole) in supra-annular areas while providing resistance against migration in the direction towards the left ventricle  18 . Relaxing the tension on the proximal end control wire  142  will also allow radial expansion of the supra-annular ring  250  (the lateral anterior anchor arch  250   a , the posterior anchor arch  250   b , and the medial anterior anchor arch  250   c ) and the undulating ring  310  of the valve assembly portion  300  (the three atrial leaflet arches  310   a ,  310   b , and  310   c ). 
     With the tensions from the proximal end control wire  142  and the anchor assembly mid-body control wire  148  removed, the anchor assembly portion  200  is fully expanded and engaged with the native mitral valve  17 . Thereafter, the clinician can remove the proximal end control wire  142  and the anchor assembly mid-body control wire  148  from engagement with the two-portion prosthetic mitral valve  400  if so desired. To do so, the clinician can simply pull on a first end of the control wire  142  and/or  148  while the second end of the control wire  142  and/or  148  is free to move. 
     Referring to  FIG. 9 , after a sufficient amount of pulling the control wires  142  and/or  148  by the clinician, the control wire  142  and/or  148  will become disengaged from the anchor assembly portion  200  as shown. In result, the anchor assembly portion  200  is fully expanded and engaged with the anatomical structure of the native mitral valve  17 . At this stage, the inner catheter  160  can continue to be coupled with the hub  210  of the anchor assembly  200 . Therefore, retrieval of the two-portion prosthetic mitral valve  400  is still possible even though the control wires  142  and  148  have been removed from engagement with the anchor assembly  200 . 
     The anchor assembly portion  200  is already deployed at this stage (other than the continued releasable coupling of the inner catheter  160  to the hub  210  of the anchor assembly  200 ). To allow the valve assembly portion  300  to fully radially expand while being nested within the anchor assembly  200 , the tension of the valve assembly distal end control wire  144  can be relaxed. Relaxing tension from the valve assembly distal end control wire  144  allows the valve assembly portion  300  to self-expand and to couple with the anchor assembly  200 . 
     In some cases, the tensions of the proximal end control wire  142  and the valve assembly distal end control wire  144  can be relaxed simultaneously. In some cases, the tensions of the proximal end control wire  142  and the valve assembly distal end control wire  144  can be relaxed serially (including any and all possible patterns of alternating, step-wise, and partial relaxations of the tensions). 
     When the valve assembly portion  300  and the anchor assembly portion  200  are coupled together, the valve assembly portion  300  is geometrically interlocked within the interior space of the anchor assembly portion  200  (e.g., in some embodiments by virtue of the tapered shape of the valve assembly portion  300  within the supra-annular ring and interior space of the anchor assembly  200 ). In particular, in some embodiments the valve assembly portion  300  is contained within the interior space between the supra-annular ring  250  and the sub-annular support arms  230   a ,  230   b ,  230   c , and  230   d  (refer to  FIG. 3 ). 
     The next step of the process for deploying the two-portion prosthetic mitral valve  400  can include removal of the valve assembly distal end control wire  144  from engagement with the valve assembly distal end coupling sites  326 . The removal of the valve assembly distal end control wire  144  can be performed as described above in reference to the proximal end control wire  142  and the anchor assembly mid-body control wire  148 . 
     After the valve assembly portion  300  has been expanded into a coupled relationship with the anchor assembly  200 , the clinician can verify that the anchor assembly portion  200  and the valve assembly portion  300  are in the desired positions. Additionally, the clinician may verify other aspects such as, but not limited to, the hemodynamic performance and sealing of the anchor assembly portion  200  and the valve assembly portion  300 . 
     The anchor assembly portion  200  and the valve assembly portion  300  of the two-portion prosthetic mitral valve  400  are deployed at this stage (other than the continued releasable coupling of the inner catheter  160  to the hub  210  of the anchor assembly  200 ). 
     The process of deploying the two-portion prosthetic mitral valve  400  arranged in the nested configuration can be completed by disengaging the inner catheter  160  from the hub  210  of the anchor assembly  200 , and removing the delivery system  100  from the patient. The SAM containment member  212  ( FIG. 3 ) may also be deployed as a result of this step. The two-portion prosthetic mitral valve  400  engaged with the native mitral valve  17  is thereafter able to take over the performance the native mitral valve function. 
     While the components of the delivery system  100  and the two-portion prosthetic mitral valve  400  are depicted in particular relative orientations and arrangements, it should be understood that the depictions are non-limiting. 
     Referring to  FIG. 10 , in some example implementations of the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another at localized portions of the three apices of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 4 ), fewer than three control wires are included. For example, in the depicted implementation the anchor assembly mid-body control wire  148  is not included, while the proximal end control wire  142  and the valve assembly distal end control wire  144  are included, for a total of two control wires. 
     In this example that uses only the two control wires  142  and  144 , the relative positioning of the inner catheter  160  (coupled to the hub  210 ) compared to the delivery catheter  140  can be adjusted to control the radial expansion of the mid-body of the anchor assembly  210  (and to control of the positions of the anchor feet  220   a ,  220   b ,  220   c , and  220   d  relative to the sub-annular gutter  19 , as shown in  FIGS. 2 and 3 ). For example, extending the inner catheter  160  further distally in comparison to the delivery catheter  140  can cause a radial contraction of the mid-body region of the anchor assembly  200 . Conversely, pulling the inner catheter  160  further proximally in comparison to the delivery catheter  140  can cause or allow a radial expansion of the mid-body region of the anchor assembly  200 . In effect, such making adjustments of the inner catheter  160  proximally/distally in comparison to the delivery catheter  140  replaces the functionality of the anchor assembly mid-body control wire  148  ( FIGS. 5-7 ). Accordingly, just the two control wires  142  and  144  are needed to perform the deployment and implantation of the two-portion prosthetic mitral valve  400  in this example. 
     Referring to  FIG. 11 , in some additional example implementations of the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another at localized portions of the three apices of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 4 ), fewer than three control wires are included. For example, in the depicted implementation the valve assembly distal end control wire  144  is not included, while the proximal end control wire  142  and the anchor assembly mid-body control wire  148  are included, for a total of two control wires. In this case, the anchor assembly mid-body control wire  148  is releasably coupled to the mid-body regions of both the anchor assembly portion  200  and the valve assembly portion  300 . Accordingly, when tension on the anchor assembly mid-body control wire  148  is relaxed, the mid-body portions of both the anchor assembly portion  200  and the valve assembly portion  300  will self-expand (e.g., to allow the anchor feet  220   a ,  220   b ,  220   c , and  220   d  to become positioned in the sub-annular gutter  19 , as shown in  FIGS. 2 and 3 ). The tension on the proximal end control wire  142  can be thereafter relaxed to allow the proximal end portions of the anchor assembly portion  200  and the valve assembly portion  300  to expand such that the atrial holding features  240   a ,  240   b , and  240   c  are in contact with or adjacent to the shelf-like supra-annular tissue surface above the annulus of the native mitral valve  17 . 
     Referring to  FIG. 12 , another example of the two-portion prosthetic mitral valve  400  is schematically depicted (e.g., shown here in a view corresponding to  FIG. 2 ) to make the structures and the transcatheter deployment technique described below easier to visualize and understand. As described above, the two-portion prosthetic mitral valve  400  includes the anchor assembly portion  200  (including the hub  210 ) and the valve assembly portion  300 . The valve assembly portion  300  is positioned within the interior space of the anchor assembly portion  200 . 
     In the depicted example embodiment of the two-portion prosthetic mitral valve  400 , the entireties of the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other (rather than being attached/affixed to each other at discrete localized portions at the apices thereof as described above). In some embodiments, the entireties of the supra-annular ring  250  and undulating ring  310  can be attached/affixed using joining techniques as described above, or by forming the frame structures of the supra-annular ring  250  and undulating ring  310  from a common piece of precursor material such that the supra-annular ring  250  and undulating ring  310  are made of shared unitary material (e.g., the same portion of material acting as the supra-annular ring  250  and undulating ring  310 ). 
     Alternatively, the example two-portion prosthetic mitral valve  400  depicted here can have just localized portions of the valleys of the supra-annular ring  250  and undulating ring  310  attached/affixed to each other (such as at valley portion  251 ), while the apices and other portions of the supra-annular ring  250  and undulating ring  310  are not attached/affixed to each other. 
     Referring also to  FIG. 13 , in some implementations the valve assembly portion  300  is positioned within the anchor assembly portion  200  during the transcatheter delivery and deployment processes of the two-portion prosthetic mitral valve  400  to the site of a native mitral valve. As described above, in the depicted embodiment the two devices (e.g., the anchor assembly portion  200  and the valve assembly portion  300 ) have the entireties of their supra-annular ring  250  and undulating ring  310  attached/affixed to each other. The two-portion prosthetic mitral valve  400  is arranged during delivery and deployment with the anchor assembly portion  200  laterally surrounding the valve assembly portion  300  so that when they are radially expanded in situ, additional portions of the anchor assembly portion  200  and the valve assembly portion  300  will become mechanically mated together. 
     In some implementations, the sheath  120  (which is a part of the transcatheter delivery system  100  as described above) can be used to simultaneously deliver the anchor assembly portion  200  and the valve assembly portion  300  to the heart  10 . That is, the anchor assembly portion  200  and the valve assembly portion  300  can be elastically collapsed to reduced diameters and constrained within the confines of the low-profile sheath  120 . In that arrangement, the sheath  120  (containing the anchor assembly portion  200  and the valve assembly portion  300  in radially collapsed configurations) can be navigated through the patient&#39;s vasculature and heart to arrive at the target location (e.g., within the heart proximate to the patient&#39;s native mitral valve). There, the anchor assembly portion  200  and the valve assembly portion  300  can be expressed out of the sheath  120 .  FIG. 13  depicts the anchor assembly portion  200  and the valve assembly portion  300  after having been expressed from the sheath  120 . As shown in this embodiment, the valve assembly portion  300  is nested within the anchor assembly  200  and the entireties of the supra-annular ring  250  and undulating ring  310  are attached/affixed to each other. 
     The transcatheter delivery system  100  can also include the inner catheter  160  (also referred to herein as a “pusher catheter  160 ”) that can be releasably coupled with the hub  210  of the anchor assembly  200 . The transcatheter delivery system  100  can also include the delivery catheter  140 . As stated above, in some embodiments one or more control wires can be used to releasably couple the anchor assembly portion  200  and the valve assembly portion  300  to the delivery catheter  140 . Such control wires can also be used by a clinician to control the radial expansion of the anchor assembly portion  200  and the valve assembly portion  300 —in some optional implementations, to control the radial expansion of the anchor assembly portion  200  independently from the radial expansion of the valve assembly portion  300  during the deployment procedure. 
     Still referring to  FIG. 13 , control wires (e.g., control wires  142 ,  144 , and  148  as described further below) can be releasably coupled around one or more regions of the anchor assembly portion  200  and/or the valve assembly portion  300 . For example, control wires can be coupled to a proximal end region, one or more mid-body regions, and/or a distal end region of the anchor assembly portion  200  and/or the valve assembly portion  300 . In some cases, a single control wire can be coupled to both the anchor assembly portion  200  and the valve assembly portion  300 . In one such example, a single control wire  142  is coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300 . Tensioning the single control wire  142  that is coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  will cause the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  to be concurrently radially contracted and constrained. Releasing tension from the single control wire  142  that is coupled to the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  will allow the proximal end regions of both the anchor assembly portion  200  and the valve assembly portion  300  to concurrently radially expand. 
     In some cases, a single control wire is coupled to only one of either the anchor assembly portion  200  or the valve assembly portion  300 . In some such cases, a first control wire can be coupled to one region of either the anchor assembly portion  200  or the valve assembly portion  300 , and a second control wire can be coupled to another region of same anchor assembly portion  200  or valve assembly portion  300 . 
     In the depicted embodiment, the anchor assembly portion  200  and the valve assembly portion  300  are jointly configured to be releasably coupled with a proximal end control wire  142  at one or more proximal end coupling sites  254  that are located at, or adjacent to, the three apices of the supra-annular ring  250  and undulating ring  310 . In addition, the anchor assembly portion  200  and the valve assembly portion  300  are jointly configured to be releasably coupled with a mid-body region control wire  148  at one or more mid-body coupling sites  256  that are located at, or adjacent to, the three valleys of the supra-annular ring  250  and undulating ring  310 . In addition, the valve assembly portion  300  is configured to be releasably coupled with a distal end region control wire  144  at one or more valve assembly distal end coupling sites  326 . 
     The control wire coupling sites (e.g., the proximal end coupling sites  254 , the mid-body coupling sites  256 , and the valve assembly distal end coupling sites  326 ) can be various types of structures to which a wire can be releasably coupled. For example, in some embodiments the control wire coupling sites can be a loop of suture material, two loops of suture material, or three or more loops of suture material. In some embodiments, the control wire coupling sites can be a structure defining an eyelet formed by, or attached to, the framework of the anchor assembly portion  200  and/or the valve assembly portion  300 . In some embodiments, the control wire coupling sites can be cells or struts of the framework of the anchor assembly portion  200  and/or the valve assembly portion  300 . Other types of suitable control wire coupling sites can also be used. 
     In the depicted embodiment, the valve assembly portion  300  is coupled to the delivery catheter  140  by: (i) the proximal end control wire  142 , (ii) the mid-body control wire  148 , and (iii) the valve assembly distal end control wire  144 . The proximal end control wire  142  can be releasably coupled with the proximal end coupling sites  254 . The mid-body control wire  148  can be releasably coupled with the mid-body coupling sites  256 . The valve assembly distal end control wire  144  can be releasably coupled with the valve assembly distal end coupling sites  326 . 
     In the depicted embodiment, the anchor assembly portion  200  is coupled to the delivery catheter  140  by: (i) the proximal end control wire  142  and (ii) the mid-body control wire  148 . The proximal end control wire  142  can be releasably coupled with the proximal end coupling sites  254 . The mid-body control wire  148  can be releasably coupled with the mid-body coupling sites  256 . 
     In some implementations, a deployment control handle/system (such as the deployment frame system  6  of  FIG. 1 ) is used to control the movements of the control wires, and by extension, the movements of the corresponding anchor assembly portion  200  and/or valve assembly portion  300  to which the control wires are coupled. For example, the tension of the control wires can be increased or decreased to thereby allow radial self-expansion, or to thereby cause radial contraction/constriction, of the corresponding anchor assembly portion  200  or valve assembly portion  300 . 
       FIGS. 14-17  schematically depict an example serial process for deploying the anchor assembly portion  200  and the valve assembly portion  300  (collectively the two-portion prosthetic mitral valve  400  as described above in reference to  FIG. 12 ) in a native heart valve  17 . 
     It should be understood that retrieval of the anchor assembly portion  200  and the valve assembly portion  300  can be readily performed at any time during the depicted sequential procedures as long as at least one of the control wires remains coupled to the anchor assembly portion  200  and/or valve assembly portion  300 . For example, as long as the proximal end control wire  142  is coupled with the proximal ends of the anchor assembly portion  200  and the valve assembly portion  300 , retrieval can be performed, for example, using the following procedure. The mid-body control wire  148  can be released and/or removed from engagement with the anchor assembly  200 . Then, the valve assembly distal end control wire  144  can be tensioned to collapse the distal end of the valve assembly portion  300 . Next, the proximal end control wire  142  that is shared by the proximal ends of the anchor assembly portion  200  and the valve assembly portion  300  can be tensioned to collapse the proximal end of the anchor assembly portion  200  and the valve assembly portion  300  such that retrieval features (e.g., hooks, clips, slots, etc.) on the delivery catheter  140  become engaged with the framework of the anchor assembly portion  200  and/or valve assembly portion  300 . Next, the anchor assembly portion  200  and the valve assembly portion  300  can be retracted into sheath  120  (e.g., by pulling the delivery catheter  140  proximally in relation to the sheath  120 ). The retrieval features on the delivery catheter  140  (with which the anchor assembly portion  200  and/or the valve assembly portion  300  are engaged) and the tensioned valve assembly distal end control wire  144  facilitate the insertion of the valve assembly portion  300  (along with the delivery catheter  140 ) into the sheath  120 . 
     Referring to  FIG. 14 , as described above the transcatheter delivery system  100  can be been used to intravascularly navigate the two-portion prosthetic mitral valve  400  to the left atrium  16 . The anchor assembly portion  200  and the valve assembly portion  300  (positioned relative to each other in the nested arrangement as shown by virtue of the frame structures that are attached/affixed to one another along the entireties of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 12 ) can be simultaneously expressed from the sheath  120  while in the left atrium  16 . In some implementations, it is desirable to orient (e.g., laterally pivot, pan, steer, etc.) the nested anchor assembly portion  200  and valve assembly portion  300  within the atrium  16  so that their longitudinal axes are generally perpendicular to the native mitral valve  17 , and coaxial with the native mitral valve  17  (e.g., to center the nested anchor assembly portion  200  with the line of coaptation of the native mitral valve  17 ). Such orienting of the partially or fully expanded anchor assembly portion  200  and valve assembly portion  300  within the atrium  16  may be advantageous versus having to orient them while they are still constrained within the delivery sheath  120 , as the latter assembly can be a relatively large and stiff catheter assembly. 
     After the two-portion prosthetic mitral valve  400  is expressed from the sheath  120  in the left atrium  16 , a clinician can relax some tension from the mid-body control wire  148  to allow the anchor assembly portion  200  to partially expand. For example, in some cases the mid-body region of the anchor assembly portion  200  may be allowed to expand about 75% of its fully expanded radial size. Accordingly, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  ( FIG. 3 ) expand radially outward. Such expansion can be performed in preparation for seating the anchor feet  220   a ,  220   b ,  220   c , and  220   d  within the sub-annular gutter  19  of the native mitral valve  17 . At this stage, the other control wires (e.g., the proximal end control wire  142  and the valve assembly distal end control wire  144 ) can remain fully tensioned such that the proximal end regions of the two-portion prosthetic mitral valve  400  and the entirety of the valve assembly  200  remain radially contracted. 
     With the mid-body region of the anchor assembly portion  200  partially expanded, the nested anchor assembly portion  200  and valve assembly portion  300  can be pushed distally (inferiorly toward the left ventricle  18 ) as indicated by arrow  50 . The anchor feet  220   a ,  220   b ,  220   c , and  220   d  may physically help to proper align the anchor assembly portion  200  (and the two-portion prosthetic mitral valve  400  as a whole) to the native mitral valve  17  as the anchor assembly portion  200  is partially pushed through the annulus of the native mitral valve  17 . The distal portions of the nested anchor assembly portion  200  and valve assembly portion  300  will pass through the annulus of the native mitral valve  17  and into the left ventricle  18  as shown. With the anchor assembly portion  200  partially radially contracted in a desired orientation, and appropriately aligned with the native mitral valve  17 , the anchor assembly portion  200  can be safely passed through the native mitral valve  17  without damaging the native mitral valve  17  and/or entangling chordae tendineae of the native mitral valve  17 . 
     Referring to  FIG. 15 , further distal movement of the two-portion prosthetic mitral valve  400  (the nested anchor assembly portion  200  and valve assembly portion  300 ) will cause the anchor feet  220   a ,  220   b ,  220   c , and  220   d  ( FIG. 3 ) to pass through the annulus of the native mitral valve  17  and into the left ventricle  18 . Then, the clinician can fully relax (or nearly fully relax) the tension from the mid-body control wire  148  to allow the mid-body region of the anchor assembly portion  200  and the valve assembly portion  300  to fully expand (or nearly fully expand). Accordingly, the anchor feet  220   a ,  220   b ,  220   c , and  220   d  can be then properly seated within the sub-annular gutter  19  of the native mitral valve  17 . 
     Referring to  FIG. 16 , as a next step of the process for implanting the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another along the entireties of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 12 ), the clinician can relax the proximal end control wire  142 . Doing so will allow the proximal end of the anchor assembly portion  200  (including the supra-annular structures of the anchor assembly portion  200 ) and the proximal end of the valve assembly portion  300  to self-expand. For example (referring also to  FIG. 3 ), relaxing the tension on the proximal end control wire  142  will allow radial expansion of the atrial holding features  240   a ,  240   b , and  240   c . The atrial holding features  240   a ,  240   b , and  240   c  are configured to contact the shelf-like supra-annular atrial tissue surface that is superior to the annulus of the native mitral valve  17 , and to thereby stabilize the anchor assembly portion  200  (and the two-portion prosthetic mitral valve  400  as a whole) in supra-annular areas while providing resistance against migration in the direction towards the left ventricle  18 . Relaxing the tension on the proximal end control wire  142  will also allow radial expansion of the supra-annular ring  250  (the lateral anterior anchor arch  250   a , the posterior anchor arch  250   b , and the medial anterior anchor arch  250   c ) and the undulating ring  310  of the valve assembly portion  300  (the three atrial leaflet arches  310   a ,  310   b , and  310   c ). 
     With the tensions from the proximal end control wire  142  and the mid-body control wire  148  removed, the anchor assembly portion  200  is fully expanded and engaged with the native mitral valve  17 . Thereafter, the clinician can remove the proximal end control wire  142  and the mid-body control wire  148  from engagement with the two-portion prosthetic mitral valve  400  if so desired. To do so, the clinician can simply pull on a first end of the control wire  142  and/or  148  while the second end of the control wire  142  and/or  148  is free to move. 
     Referring to  FIG. 17 , after a sufficient amount of pulling the control wires  142  and/or  148  by the clinician, the control wire  142  and/or  148  will become disengaged from the anchor assembly portion  200  as shown. In result, the anchor assembly portion  200  is fully expanded and engaged with the anatomical structure of the native mitral valve  17 . At this stage, the inner catheter  160  can continue to be coupled with the hub  210  of the anchor assembly  200 . Therefore, retrieval of the two-portion prosthetic mitral valve  400  is still possible even though the control wires  142  and  148  have been removed from engagement with the anchor assembly  200 . 
     The anchor assembly portion  200  is already deployed at this stage (other than the continued releasable coupling of the inner catheter  160  to the hub  210  of the anchor assembly  200 ). To allow the valve assembly portion  300  to fully radially expand while being nested within the anchor assembly  200 , the tension of the valve assembly distal end control wire  144  can be relaxed. Relaxing tension from the valve assembly distal end control wire  144  allows the valve assembly portion  300  to self-expand and to couple with the anchor assembly  200 . 
     In some cases, the tensions of the proximal end control wire  142  and the valve assembly distal end control wire  144  can be relaxed simultaneously. In some cases, the tensions of the proximal end control wire  142  and the valve assembly distal end control wire  144  can be relaxed serially (including any and all possible patterns of alternating, step-wise, and partial relaxations of the tensions). 
     When the valve assembly portion  300  and the anchor assembly portion  200  are coupled together, the valve assembly portion  300  is geometrically interlocked within the interior space of the anchor assembly portion  200 . In particular, in some embodiments the valve assembly portion  300  is contained within the interior space between the supra-annular ring  250  and the sub-annular support arms  230   a ,  230   b ,  230   c , and  230   d  (refer to  FIG. 3 ). 
     The next step of the process for deploying the two-portion prosthetic mitral valve  400  can include removal of the valve assembly distal end control wire  144  from engagement with the valve assembly distal end coupling sites  326 . The removal of the valve assembly distal end control wire  144  can be performed as described above in reference to the proximal end control wire  142  and the mid-body control wire  148 . 
     After the valve assembly portion  300  has been expanded into a coupled relationship with the anchor assembly  200 , the clinician can verify that the anchor assembly portion  200  and the valve assembly portion  300  are in the desired positions. Additionally, the clinician may verify other aspects such as, but not limited to, the hemodynamic performance and sealing of the anchor assembly portion  200  and the valve assembly portion  300 . 
     The anchor assembly portion  200  and the valve assembly portion  300  of the two-portion prosthetic mitral valve  400  are deployed at this stage (other than the continued releasable coupling of the inner catheter  160  to the hub  210  of the anchor assembly  200 ). 
     The process of deploying the two-portion prosthetic mitral valve  400  arranged in the nested configuration can be completed by disengaging the inner catheter  160  from the hub  210  of the anchor assembly  200 , and removing the delivery system  100  from the patient. The SAM containment member  212  ( FIG. 3 ) may also be deployed as a result of this step. The two-portion prosthetic mitral valve  400  engaged with the native mitral valve  17  is thereafter able to take over the performance the native mitral valve function. 
     While the components of the delivery system  100  and the two-portion prosthetic mitral valve  400  are depicted in particular relative orientations and arrangements, it should be understood that the depictions are non-limiting. 
     Referring to  FIG. 18 , in some example implementations of the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another along the entireties of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 12 ), fewer than three control wires are included. For example, in the depicted implementation the mid-body control wire  148  is not included, while the proximal end control wire  142  and the valve assembly distal end control wire  144  are included, for a total of two control wires. 
     In this example that uses only the two control wires  142  and  144 , the relative positioning of the inner catheter  160  (coupled to the hub  210 ) compared to the delivery catheter  140  can be adjusted to control the radial expansion of the mid-body of the anchor assembly  210  (and to control of the positions of the anchor feet  220   a ,  220   b ,  220   c , and  220   d  relative to the sub-annular gutter  19 , as shown in  FIGS. 2 and 3 ). For example, extending the inner catheter  160  further distally in comparison to the delivery catheter  140  can cause a radial contraction of the mid-body region of the anchor assembly  200 . Conversely, pulling the inner catheter  160  further proximally in comparison to the delivery catheter  140  can cause or allow a radial expansion of the mid-body region of the anchor assembly  200 . In effect, such making adjustments of the inner catheter  160  proximally/distally in comparison to the delivery catheter  140  replaces the functionality of the mid-body control wire  148  ( FIGS. 13-15 ). Accordingly, just the two control wires  142  and  144  are needed to perform the deployment and implantation of the two-portion prosthetic mitral valve  400  in this example. 
     Referring to  FIG. 19 , in some additional example implementations of the two-portion prosthetic mitral valve  400  arranged in the nested configuration (with the frame structures of the anchor assembly portion  200  and the valve assembly portion  300  attached/affixed to one another along the entireties of the supra-annular ring  250  and undulating ring  310  as described above, e.g., in reference to  FIG. 12 ), fewer than three control wires are included. For example, in the depicted implementation the valve assembly distal end control wire  144  is not included, while the proximal end control wire  142  and the mid-body control wire  148  are included, for a total of two control wires. In this case, the mid-body control wire  148  is releasably coupled to the mid-body regions of both the anchor assembly portion  200  and the valve assembly portion  300 . Accordingly, when tension on the mid-body control wire  148  is relaxed, the mid-body portions of both the anchor assembly portion  200  and the valve assembly portion  300  will self-expand (e.g., to allow the anchor feet  220   a ,  220   b ,  220   c , and  220   d  to become positioned in the sub-annular gutter  19 , as shown in  FIGS. 2 and 3 ). The tension on the proximal end control wire  142  can be thereafter relaxed to allow the proximal end portions of the anchor assembly portion  200  and the valve assembly portion  300  to expand such that the atrial holding features  240   a ,  240   b , and  240   c  are in contact with or adjacent to the shelf-like supra-annular tissue surface above the annulus of the native mitral valve  17 . 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the scope of the invention. Accordingly, other embodiments are within the scope of the following claims.