Patent Publication Number: US-11638643-B1

Title: Prosthetic heart valves

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 63/390,810, filed Jul. 20, 2022. The disclosure of the prior application is considered part of (and is incorporated by reference in) the disclosure of this application. 
    
    
     FIELD OF INVENTION 
     This disclosure generally relates to prosthetic heart valve systems. For example, this disclosure relates to transcatheter deliverable prosthetic heart valves that are adapted to be used to replace a sub-optimally functioning native heart valve, including but not limited to a tricuspid valve. 
     BACKGROUND 
     A human heart includes four types of heart valves that are arranged to ensure blood flow in specific directions: mitral, tricuspid, aortic and pulmonary valves. The aortic and pulmonary valves are semilunar valves, which are in the arteries leaving the heart, and prevent blood from flowing back into left ventricle and right ventricle respectively when closed. The mitral and tricuspid valves are atrio-ventricular valves, which are between the atria and the ventricles, and prevent blood from flowing back into left atrium and right atrium respectively when closed. Conditions of stenosis (when valve does not open fully) as well as regurgitation/insufficiency (when valve does not close properly resulting in leaks) are recognized as significant contributors to mortality and morbidity. 
     Some valve replacement systems include valve prostheses that are compressed into a delivery catheter, also referred to as transcatheter valves, so as to avoid open-heart surgery. Many transcatheter valve prostheses have a tubular frame that may or may not be axisymmetric, and include two or more leaflets. While these transcatheter valve prostheses can be compressed into a catheter, they may still require a large delivery system (for example, a required catheter size of 45 French). This is especially true in case of mitral valve replacement systems and tricuspid valve replacement systems, which often require valve prostheses with a larger profile. 
     SUMMARY 
     Some embodiments described herein include a prosthetic heart valve that may be delivered to a targeted native heart valve site via one or more delivery catheters. In some embodiments, a prosthetic heart valve includes structural features that securely anchor the prosthetic heart valve to the anatomy at the site of the native heart valve. Such structural features can provide robust migration resistance. In addition, the prosthetic heart valves can include structural features that improve sealing between the prosthetic valve and native valve anatomy to mitigate paravalvular leakage. In particular implementations, the prosthetic heart valves occupy a small delivery profile, thereby facilitating a smaller delivery catheter system for advancement to the heart. Some delivery catheter systems can include a curved inner catheter to facilitate deployment of the prosthetic heart valve to a native tricuspid valve site via a superior vena cava or inferior vena cava. 
     In one aspect, this disclosure is directed to a prosthetic heart valve that includes a main body comprising an inflow end portion and an outflow end portion, and an occluder extending between the inflow end and outflow end portions and comprising valve leaflets attached to the main body in an arrangement that: (i) allows blood flow through the occluder in a direction from the inflow end portion toward the outflow end portion along a central axis of the occluder and (ii) prevents blood flow through the occluder in a direction from the outflow end portion toward the inflow end portion. The prosthetic heart valve also includes a first anterior flap extending from the outflow end portion in a first direction that is transverse to the central axis; a posterior flap extending from the outflow end portion in a second direction that is opposite of the first direction; and a posterior arm extending from the inflow end portion in the second direction. 
     Such a prosthetic heart valve may optionally include one or more of the following features. The prosthetic heart valve may also include an anterior arm extending from the inflow end portion in the first direction. The prosthetic heart valve may also include a second anterior flap extending from the outflow end portion in the first direction. The first and second anterior flaps may overlap each other. A cross-sectional shape of the first and second anterior flaps taken perpendicularly to the first direction may be arcuate. 
     In another aspect, this disclosure is directed to another prosthetic heart valve. The prosthetic heart valve includes a main body comprising an inflow end portion and an outflow end portion, and an occluder extending between the inflow end and outflow end portions and comprising valve leaflets attached to the main body in an arrangement that: (i) allows blood flow through the occluder in a direction from the inflow end portion toward the outflow end portion along a central axis of the occluder and (ii) prevents blood flow through the occluder in a direction from the outflow end portion toward the inflow end portion. The prosthetic heart valve also includes an anterior flap extending from the outflow end portion in a first direction that is transverse to the central axis; a posterior flap extending from the outflow end portion in a second direction that is opposite of the first direction; and an anterior arm extending from the inflow end portion in the first direction. 
     In another aspect, this disclosure is directed to another prosthetic heart valve. The prosthetic heart valve includes a main body comprising an inflow end portion and an outflow end portion, and an occluder extending between the inflow end and outflow end portions and comprising valve leaflets attached to the main body in an arrangement that: (i) allows blood flow through the occluder in a direction from the inflow end portion toward the outflow end portion along a central axis of the occluder and (ii) prevents blood flow through the occluder in a direction from the outflow end portion toward the inflow end portion. The prosthetic heart valve also includes a first anterior flap extending from the outflow end portion in a first direction that is transverse to the central axis; and a second anterior flap extending from the outflow end portion in the first direction. A cross-sectional shape of the first and second anterior flaps taken perpendicularly to the first direction is arcuate from an outer edge of the first anterior flap to an outer edge of the second anterior flap. 
     In another aspect, this disclosure is directed to another prosthetic heart valve. The prosthetic heart valve includes a main body comprising an inflow end portion and an outflow end portion, and an occluder extending between the inflow end and outflow end portions and comprising valve leaflets attached to the main body in an arrangement that: (i) allows blood flow through the occluder in a direction from the inflow end portion toward the outflow end portion along a central axis of the occluder and (ii) prevents blood flow through the occluder in a direction from the outflow end portion toward the inflow end portion. The prosthetic heart valve also includes a first anterior flap extending from the outflow end portion in a first direction that is transverse to the central axis: a second anterior flap extending from the outflow end portion in the first direction; a first posterior flap extending from the outflow end portion in a second direction that is opposite of the first direction; and a second posterior flap extending from the outflow end portion in the second direction. A passageway is defined between the first and second posterior flaps. The first and second posterior flaps extend from the outflow end portion farther than the first and second anterior flaps. 
     In another aspect, this disclosure is directed to a method of deploying a prosthetic heart valve. The method includes engaging any of the prosthetic heart valves described herein with anatomical structures of a native tricuspid valve. The lateral anterior flap extends into a right ventricular outflow tract (RVOT) and engages with a lateral wall of the RVOT to provide anchoring during diastole. 
     In another aspect, this disclosure is directed to another method of deploying a prosthetic heart valve. The method includes engaging any of the prosthetic heart valves described herein with anatomical structures of a native tricuspid valve. A distal end portion of the posterior arm rests against an interior wall of an inferior vena cava, or coronary sinus, or a right atrium. 
     In another aspect, this disclosure is directed to another method of deploying a prosthetic heart valve. The method includes engaging any of the prosthetic heart valves described herein with anatomical structures of a native tricuspid valve. A distal end portion of the anterior arm rests against an interior wall of a right atrial appendage. 
     Various types of deployment systems may be used in combination with the prosthetic tricuspid valves described herein. In some embodiments described herein, such a deployment system may include an outer sheath catheter defining a first lumen; a middle deflectable catheter slidably disposed in the first lumen and defining a second lumen, the middle deflectable catheter comprising a selectively deflectable distal end portion with at least one plane of deflection; and an inner control catheter slidably disposed in the second lumen and including one or more control wires that configure the inner control catheter to releasably couple with a prosthetic heart valve. The inner control catheter includes a distal end portion that elastically transitions to a naturally curved configuration when the inner control catheter converts from being radially constrained to being radially unconstrained. In some embodiments, the distal end portion defines an interior angle of less than 135 degrees when in the naturally curved configuration. 
     In another aspect, this disclosure is directed to another method of deploying a prosthetic heart valve. The method includes advancing the prosthetic heart valve toward a native tricuspid valve, via a jugular vein and a superior vena cava, while the prosthetic heart valve is releasably coupled to a prosthetic heart valve deployment system and diametrically constrained in a low profile delivery configuration. The prosthetic heart valve deployment system includes an outer sheath catheter defining a first lumen; a middle deflectable catheter slidably disposed in the first lumen and defining a second lumen, the middle deflectable catheter comprising a selectively deflectable distal end portion; and an inner control catheter slidably disposed in the second lumen and including one or more control wires that are releasably coupled with the prosthetic heart valve. The inner control catheter includes a distal end portion constrained in the first lumen. The method also includes retracting the outer sheath relative to the inner control catheter to allow the distal end portion of the inner control catheter to become radially unconstrained and to elastically transition to a curved configuration; and deflecting the selectively deflectable distal end portion of the middle deflectable catheter so that the inner control catheter and the middle deflectable catheter in combination are curved by at least 90° relative to the outer sheath. 
     In another aspect, this disclosure is directed to a prosthetic heart valve deployment system that includes: an outer sheath catheter defining a first lumen; a middle deflectable catheter slidably disposed in the first lumen and defining a second lumen, the middle deflectable catheter comprising a selectively deflectable distal end portion with at least one plane of deflection; and an inner control catheter slidably disposed in the second lumen and including one or more control wires that configure the inner control catheter to releasably couple with a prosthetic heart valve. The inner control catheter includes a distal end portion that elastically transitions to a naturally curved configuration when the inner control catheter converts from being radially constrained to being radially unconstrained. 
     In another aspect, this disclosure is directed to another method of deploying a prosthetic heart valve. The method includes advancing the prosthetic heart valve toward a native tricuspid valve, via a femoral vein and an inferior vena cava, while the prosthetic heart valve is releasably coupled to a prosthetic heart valve deployment system and diametrically constrained in a low profile delivery configuration. The prosthetic heart valve deployment system includes an outer sheath catheter defining a first lumen; a middle deflectable catheter slidably disposed in the first lumen and defining a second lumen, the middle deflectable catheter comprising a selectively deflectable distal end portion; and an inner control catheter slidably disposed in the second lumen and including one or more control wires that are releasably coupled with the prosthetic heart valve. The inner control catheter includes a curved distal end portion that is curved by less than 20° when constrained in the first lumen. The method also includes advancing the inner control catheter relative to the outer sheath to allow the curved distal end portion to become unconstrained and to elastically transition to a curved configuration that is curved by at least 45° relative to the outer sheath; and deflecting the selectively deflectable distal end portion of the middle deflectable catheter so that the inner control catheter and the middle deflectable catheter in combination are curved by at least 90° relative to the outer sheath. 
     Any of the prosthetic heart valves described herein may optionally include one or more of the following additional features. In some embodiments, portions of the first anterior flap and the second anterior flap overlap each other. The prosthetic tricuspid valve may also include a posterior flap extending laterally from the end of the main body in an opposite direction as the first and second anterior flaps. In some embodiments, the first and second anterior flaps extend farther laterally than the posterior flap. In particular embodiments, the first and second anterior flaps in combination are wider (in the septal to lateral direction) than the posterior flap. A framework of the prosthetic tricuspid valve (that comprises the main body, the first and second anterior flaps, and the posterior flap) may be made of a single, unitary material that was cut and expanded. In some embodiments, a distal tip portion of the posterior flap extends along an axis that is at a non-zero angle relative to a portion of the posterior flap that extends directly from the main body. In some examples, having the portions of the first anterior flap and the second anterior flap that overlap each other increases a bending resistance of the first anterior flap and the second anterior flap in combination as compared to the first anterior flap and the second anterior flap individually. Having the portions of the first anterior flap and the second anterior flap as separate members can configure the prosthetic tricuspid valve to have a pacemaker lead pass through the prosthetic tricuspid valve between the first and second anterior flaps. The prosthetic tricuspid valve may also include one or more additional antenor flaps extending laterally from the end of the main body in the same direction as the first and second anterior flaps. The prosthetic tricuspid valve may also include two or more posterior flaps extending laterally from the end of the main body in an opposite direction as the first and second anterior flaps. Having the portions of the first posterior flap and the second posterior flap as separate members can configure the prosthetic tricuspid valve to have a pacemaker lead pass through the prosthetic tricuspid valve between the first and second posterior flaps. In some embodiments, a transverse cross-section of the main body has an oval shaped outer profile that defines a major diameter and a minor diameter. The minor diameter is shorter than the major diameter. The occluder may have a circular cross-sectional shape, and the anterior and posterior flaps may extend transversely to the major diameter. The prosthetic heart valve may also include a leaflet engagement member extending from the main body, a portion of the leaflet engagement member extending toward the inflow end portion and terminating at a free end. The leaflet engagement member may extend in the second direction. The posterior flap may extend farther away from the main body than the leaflet engagement member. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG.  1    shows a sectional view of a human heart including four heart valves (mitral valve, tricuspid valve, aortic valve, and pulmonary valve) that allow blood flow through specific pathways. The mitral and tricuspid valve are arranged to prevent backflow of blood into left atrium and right atrium respectively when the left and right ventricle contract respectively. 
         FIG.  2    shows a top view of the tricuspid valve of  FIG.  1    and including three native leaflets: anterior, posterior and septal. 
         FIG.  3    shows another sectional view of a human heart including the four chambers (right atrium, right ventricle, left atrium, and left ventricle) and major conduits that deliver blood to the heart and transport blood away from the heart. 
         FIG.  4    shows a schematic view of the right side of the heart of  FIG.  3   , including the right atrium (“RA”), right ventricle (“RV”), and right ventricle outflow tract (“RVOT”), in accordance with some native anatomies. 
         FIG.  5    shows another schematic view of the right side of the heart of  FIG.  3   , including the RA, RV, and RVOT, in accordance with some native anatomies. 
         FIG.  6    shows a side view of an example prosthetic heart valve in accordance with some embodiments described herein. 
         FIG.  7    shows a side view of the prosthetic heart valve of  FIG.  6    engaged within a native tricuspid valve. 
         FIG.  8    shows a top view of the prosthetic heart valve of  FIG.  6   . 
         FIG.  9    shows a top view of a frame of another example prosthetic heart valve in accordance with some embodiments described herein. 
         FIG.  10    schematically illustrates a transverse plane view of a native tricuspid valve annulus and RVOT. 
         FIG.  11    schematically illustrates a top view of the prosthetic heart valve of  FIG.  6   . 
         FIG.  12    schematically illustrates the prosthetic heart valve of  FIG.  11    engaged with the native tricuspid valve annulus and RVOT of  FIG.  10   . 
         FIG.  13    schematically illustrates a cross-section view taken along the cutting plane  13 - 13  of  FIG.  12    and including the anterior flaps of the prosthetic heart valve and the RVOT. 
         FIG.  14    schematically shows a longitudinal plane cross-section view of an anterior portion of a native tricuspid valve annulus and the anterior flaps of prosthetic heart valves described herein. 
         FIG.  15    is an anterior side view of the prosthetic heart valves described herein showing a cross-sectional shape of the anterior flaps. 
         FIG.  16    shows a top view of some prosthetic heart valves described herein. 
         FIG.  17    shows a plan view of an example prosthetic heart valve deployment system in accordance with some embodiments. 
         FIG.  18    shows an expanded view of a distal end portion of the prosthetic heart valve deployment system of  FIG.  17   . 
         FIG.  19    schematically illustrates a side view of the prosthetic tricuspid valves described herein. 
         FIG.  20    schematically shows the prosthetic tricuspid valve of  FIG.  19    coupled with the prosthetic heart valve deployment system of  FIG.  17   . 
         FIGS.  21  through  30    show an example trans-jugular method of deploying the prosthetic tricuspid valves described herein using the prosthetic heart valve deployment system of  FIG.  17   . 
         FIG.  31    schematically shows a top view of another example prosthetic heart valve in accordance with some embodiments described herein. 
         FIGS.  32 - 37    schematically depict an example trans-femoral method of deploying the prosthetic heart valve of  FIG.  31    using the prosthetic heart valve deployment system of  FIG.  17   . 
         FIG.  38    is a perspective view of an example frame that can be used for the prosthetic heart valves described herein. 
         FIG.  39    is a top view of the frame of  FIG.  38   . 
         FIG.  40    is a side view of the frame of  FIG.  38   . 
         FIG.  41    is a perspective view of another example frame that can be used for the prosthetic heart valves described herein. 
         FIG.  42    is a top view of the frame of  FIG.  41   . 
         FIG.  43    is a side view of the frame of  FIG.  41   . 
     
    
    
     DETAILED DESCRIPTION 
     Some embodiments described herein include a prosthetic heart valve that may be delivered to a targeted native heart valve site via one or more delivery catheters. In some embodiments, a prosthetic heart valve includes structural features that securely anchor the prosthetic heart valve to the anatomy at the site of the native heart valve. Such structural features can provide robust migration resistance during diastole and systole. In addition, the prosthetic heart valves can include structural features that improve sealing between the prosthetic valve and native valve anatomy to mitigate paravalvular leakage. In particular implementations, the prosthetic heart valves occupy a small delivery profile, thereby facilitating a smaller delivery catheter system for advancement to the heart. Some catheter-based prosthetic heart valve deployment systems can include a curved inner catheter to facilitate deployment of the prosthetic heart valve to a native tricuspid valve site via a superior vena cava or inferior vena cava. 
     Referring to  FIG.  1   , certain aspects of the concepts described herein regarding the heart valve replacement systems can be implemented in prosthetic valve designs that are intended for use at any of the four heart valves that allow blood flow through a specific pathway: mitral valve, tricuspid valve, aortic valve and the pulmonary valve.  FIG.  2    depicts, for example, a targeted site at a tricuspid valve of the heart. The tricuspid valve  10  includes an anterior leaflet  11   a , a posterior leaflet  11   p , and a septal leaflet  11   s , and an annulus  12 . In some circumstances, the tricuspid valve  10  may undergo stenosis or anatomical changes that cause tricuspid regurgitation, such as instances in which the distance between the anterio-septal commissure and the anterio-posterior commissure of the native tricuspid valve increases with the progression of a diseased state due to dilation of the annulus  12  of the tricuspid valve  10 . 
       FIG.  3    illustrates a longitudinal sectional view of a human heart  1  that shows the four chambers (right atrium, right ventricle, left atrium, and left ventricle) and the major conduits that deliver blood to the heart  1  and transport blood away from the heart  1 . The tricuspid valve  10  is located between the right atrium and the right ventricle. Blood enters the right atrium from the superior vena cava and the inferior vena cava. Blood flows from the right atrium to the right ventricle through the tricuspid valve  10 . The blood exits the right ventricle and enters the main pulmonary artery (“MPA”) via the RVOT that is adjacent to the tricuspid valve  10 . 
       FIGS.  4  and  5    schematically illustrate the right side of the heart  1 , including the right atrium, right ventricle, and tricuspid valve  10  therebetween. Naturally, there is anatomical variability among the human population.  FIGS.  4  and  5    depict some of the anatomical variability. In particular,  FIG.  4    shows a heart  1   a  that includes the presence of a posterior shelf  11 . In contrast,  FIG.  5    shows a heart  1   b  with a lack of any such posterior shelf. Some human hearts (such as the heart  1   a ) have a posterior shelf  11 , but some human hearts (such as the heart  1   b ) do not have a distinct posterior shelf. The prosthetic tricuspid valves disclosed herein are designed to be implantable in the native tricuspid valve  10  of both types of anatomies (e.g., both the heart  1   a  with the posterior shelf  11 , and the heart  1   b  without the posterior shelf). 
     The posterior shelf  11 , when present, provides an anatomical structure that can be used advantageously for the anchorage of a prosthetic tricuspid valve (as described further herein). When no such posterior shelf is present (e.g., as shown in  FIG.  5   ), robust anchorage of a prosthetic tricuspid valve at the site of the native tricuspid valve  10  is more challenging. Nevertheless, and as described in U.S. patent application Ser. No. 17/747,507 filed on May 18, 2022) which is hereby incorporated by reference in its entirety and for all purposes), the prosthetic tricuspid valves described herein can be successfully used in such a case. 
       FIGS.  6 - 8    illustrate an example prosthetic tricuspid valve  100  (or simply “valve  100 ”) in accordance with some example embodiments of this disclosure. The valve  100  includes a frame  102  and a covering  104  attached to the frame  102 .  FIG.  7    shows the valve  100  engaged with a native tricuspid valve  10  between the right atrium and the right ventricle. 
     The frame  102  comprises a cellular structure that provides mechanical support for the shape and structures of the valve  100 . In some embodiments, the frame  102  is made from nitinol (NiTi), stainless steel, cobalt chromimum, MP35N, titanium, polymeric materials, other biocompatible materials, or any combination thereof. Some or all parts of the frame  102  may be covered by the covering  104 . 
     The frame  102  can be made of a laser cut, expanded, and shape-set material in some embodiments. The frame  102  is self-expanding in some embodiments. In some embodiments, the precursor material is tubular NiTi, a NiTi sheet, or other suitable types of precursor materials. 
     The covering  104  may made of a biocompatible polymer material (e.g., expanded polytetrafluoroethylene (ePTFE), UHMWPE (ultra-high molecular weight polyethylene), nylon, polyester (e.g., DACRON), or another synthetic material), natural tissues (e.g., bovine, porcine, ovine, or equine pericardium), or any combination thereof. The covering  104  can be attached to the frame  102  by suturing, using clips, adhesives, and/or any other suitable attachment process. 
     The valve  100  includes a main body  106 . The main body  106  includes an occluder  110  (e.g., a one-way valve) that defines a central axis  101 . The occluder  110  has flexible leaflets  111   a ,  111   b , and  111   c  (collectively  111   a - c ) that cause the occluder  110  to function as a one-way valve (in a manner like a native tricuspid valve). The occluder  110  defines a circular inlet where the edges of leaflets  111   a - c  are attached to the frame  102 . Other side edges of the leaflets  111   a - c  are attached to posts  112   a ,  112   b , and  112   c  of the frame  102 . The leaflets  111   a - c  also have distal free edges that are coaptable with each other to facilitate the opening and sealing of the occluder  110 . 
     The main body  106  of the valve  100  includes an inflow end portion  102   i , a mid-body portion  102   m , and an outflow end portion  102   o . The inflow end portion  102   i  includes a series of arch shapes in the frame  102 , circumscribing the axis  101  of the occluder  110 . The occluder leaflets  111   a - c  allow blood to directionally flow through the occluder  110  from the inflow end portion  102   i  to the outflow end portion  102   o . The leaflets  111   a - c  of the occluder  110  close against each other (e.g., coapt) to prevent blood flow in the other direction (to prevent blood flow from the outflow end portion  102   o  to the inflow end portion  102   i ). 
     The embodiments of the valve  100  depicted in this disclosure employ three occluder leaflets  111   a - c , which is referred to as tri-leaflet occluder. The occluder  110  of the valve  100  can optionally employ configurations other than a tri-leaflet occluder. For example, bi-leaflet, quad-leaflet, or mechanical valve constructs can be used in some embodiments. In particular implementations described herein, the flexible leaflets  111   a - c  are made of natural tissues such as porcine or bovine or equine or ovine pericardium. In such embodiments, the tissues are chemically cross-linked using glutaraldehyde or formaldehyde, or other aldehydes commonly used as crosslinking agents. In other embodiments, the flexible leaflets  111   a - c  are made of polymers such as polyurethane, polyester (DACRON) or expanded polytetrafluoroethylene (ePTFE). In some embodiments, the flexible leaflets  111   a - c  are attached to structural frame  102  using sutures that could be made of materials including but not limited to UHMWPE, nylon, or polyester (e.g., DACRON). 
     The valve  100  also includes a first anterior flap  120   a  (or septal anterior flap  120   a ), a second anterior flap  120   b  (or lateral anterior flap  120   b ), and at least one posterior flap  130 . The frame  102  and the covering  104  combine to form the anterior flaps  120   a - b  and the posterior flap  130 . The frame  102  provides the structure of the anterior flaps  120   a - b  and the posterior flap  130 , and the covering  104  provides occlusion. While the depicted embodiment includes two anterior flaps  120   a - b , in some embodiments one, three, four, or more than four anterior flaps can be included. While the depicted embodiment includes a single posterior flap  130 , in some embodiments two, three, four, or more than four posterior flaps can be included. For instance,  FIG.  31    refers to an embodiment with two posterior flaps  330   a  and  330   b.    
     The anterior flaps  120   a - b  and the posterior flap  130  extend away from the outflow end portion  102   o  of the main body  106  in opposite directions away from the axis  101 . That is, the posterior flap  130  extends directionally opposite from the extension direction of the first and second anterior flaps  120   a - b . In some embodiments, the posterior flap  130  extends 180° opposite from the extension direction of the first and second anterior flaps  120   a - b . In particular embodiments, the anterior flaps  120   a - b  and the posterior flap  130  extend away from the outflow end portion  102   o  of the main body  106  transverse to the axis  101  of the occluder  110 . 
     In the depicted embodiment, the first anterior flap  120   a  and the second anterior flap  120   b  each include a mid-body portion  124  ( FIG.  6   ) that is bent at an angle so as to direct terminal end portions of the anterior flaps  120   a - b  toward the inlet end of the main body  106 . In some embodiments, the anterior flaps  120   a - b  initially extend away from the main body  106  substantially perpendicularly (e.g., within about 80° to 100°) to the central axis  101 . Then, at the mid-body portion  124 , the anterior flaps  120   a - b  have a bend that defines an angle θ in a range of between 20° to 60°, or 30° to 60°, or 30° to 70°, or 40° to 60°, or 40° to 70°, or 40° to 50°, without limitation. 
     The bends in the mid-body  106  of the anterior flaps  120   a - b  can allow the anterior flaps  120   a - b  to conform to the contours of the wall that defines the RVOT (as shown in  FIG.  7   ). Accordingly, the bent anterior flaps  120   a - b  can reduce the potential of the anterior flaps  120   a - b  to restrict blood flow through the RVOT in some cases. 
     As shown in  FIG.  8   , the depicted embodiment includes an opening  126   a  that is defined by the covering  104  located at a terminal end portion of the first anterior flap  120   a . Additionally, the covering  104  on the second anterior flap  120   b  defines an opening  126   b  at a terminal end portion of the second anterior flap  120   b.    
     The openings  126   a - b  in the end portions of the anterior flaps  120   a - b  allow blood to flow through the anterior flaps  120   a - b  (via the openings  126   a - b ). This can be beneficial because in some implementations the anterior flaps  120   a - b  extend into the RVOT. Accordingly, such openings  126   a - b  may in some cases reduce the potential of the anterior flaps  120   a - b  to restrict blood flow through the RVOT. 
     In the depicted embodiment, the posterior flap  130  includes a first portion  130   a  and a second portion  130   b  that are arranged at an angle in relation to each other. The first portion  130   a  extends away from the outflow end portion  102   o  of the main body  106  generally transverse to the axis  101  of the occluder  110 . The second portion  130   b  of the posterior flap  130  extends from the first portion  130   a . In the depicted embodiment, the second portion  130   b  extends generally parallel to the axis  101  of the occluder  110 . The angle defined between the first portion  130   a  and the second portion  130   b  can be in a range of 80° to 100°, or 70° to 110°, or 60° to 120°, or 50° to 130°, or 40° to 140°, without limitation. 
     The first anterior flap  120   a  and the second anterior flap  120   b  each extend in the same direction, which is opposite of the direction that the posterior flap  130  extends. In the depicted embodiment, portions of the first anterior flap  120   a  and the second anterior flap  120   b  overlap each other. An advantage of having the two separate anterior flaps  120   a - b  (rather than a single larger anterior flap) is that the anterior flap portion of the valve  100  can be radially compressed to a smaller profile for transcatheter delivery by the virtue of having the two separate anterior flaps  120   a - b  (as compared to having a single larger anterior flap). 
     In some embodiments, as shown in  FIG.  7   , the first and second anterior flaps  120   a - b  extend into the RVOT and overlap one axially on top of the other. This arrangement is functionally akin to a cantilevered beam arrangement. With the first and second anterior flaps  120   a - b  overlapping on each other, the bending resistance of the first and second anterior flaps  120   a - b  is increased (as compared to a single flap or non-overlapping flaps). This arrangement enables an advantageous extent of rigidity, without having to use framework members that are larger in cross-section. That is, the overlapping arrangement of the first and second anterior flaps  120   a - b  allow for the use of smaller framework members, which in turn importantly allows for a smaller collapsed delivery size (diameter). In other words, overlapping arrangement of the first and second anterior flaps  120   a - b  provides a support structure that is thicker without having to use a material with higher wall thickness (from which the framework is created); ultimately providing the bending stiffness or rigidity that keeps the valve  100  stable when RV pressure acts on the valve  100 . 
     In the depicted embodiment, an open passage  122  (e.g., see  FIG.  16   ) is defined between the first anterior flap  120   a  and the second anterior flap  120   b . The open passage  122  can be used, for example, for passing a pacemaker lead through the valve  100 , without disturbing the functioning of the occluder  110 . 
     Accordingly, the valve  100  can facilitate the pass-through of the pacemaker lead while still providing sealing to prevent tricuspid valve regurgitation from the RV to the RA. In some cases, the pacemaker lead is pre-existing and the valve  100  is implanted subsequently (with the open passage  122  being used to receive the pacemaker lead). In other cases, the valve  100  can be pre-existing and the pacemaker lead can be subsequently passed through the open passage  122 . This could take place both during the same implant procedure, or as a subsequent procedure. 
       FIG.  31    illustrates another example prosthetic valve  300 . The valve  300  defines an open passage  332  between the posterior flaps  330   a  and  330   b  that can be used, for example, for passing a pacemaker lead through the valve  300 , without disturbing the functioning of the occluder  310 . In some cases, the pacemaker lead is pre-existing and the valve  300  is implanted subsequently (with the open passage  322  being used to receive the pacemaker lead). In other cases, the valve  300  can be pre-existing and the pacemaker lead can be subsequently passed through the open passage  322 . 
     Still referring to  FIGS.  6 - 8   , the valve  100  also includes one or more leaflet engagement members  140 . In the depicted embodiment, the valve  100  includes two leaflet engagement members: a first leaflet engagement member  140   a  and a second engagement member  140   b . In the depicted embodiment, the leaflet engagement members  140   a - b  extend from the outflow end portion  102   o  of the main body  106 . In some embodiments, the leaflet engagement members  140   a - b  extend from the mid-body portion  102   m  of the main body  106 . 
     The leaflet engagement members  140   a - b  extend from the frame  102  and bend toward the inflow end portion  102   i  of the main body  106 . In other words, a portion of each leaflet engagement member  140   a - b  extends toward the inflow end portion  102   i  of the main body  106 . A space, groove, or slot is defined between the leaflet engagement members  140   a - b  and the outer surface of the frame  102  (with the covering  104  being present on the frame  102  and leaflet engagement members  140   a - b ). As described further below, the space, groove, or slot receives and mechanically captures/holds a portion of a native leaflet (e.g., the posterior leaflet  11   p  and/or the septal leaflet  11   s ) to provide migration resistance for the valve  100 . 
     In the depicted embodiment, the leaflet engagement members  140   a - b  extend from the frame  102  of the main body  106  in the same direction as the posterior flap  130 . The posterior flap  130  extends away from the main body  106  farther than the leaflet engagement members  140   a - b . Various other arrangements of the leaflet engagement members  140   a - b  and the posterior flap  130  are also envisioned and within the scope of this disclosure. 
     The leaflet engagement members  140   a - b  may be U-shaped wire loops, as in the depicted embodiment. The wire loops that make up the leaflet engagement members  140   a - b  can be continuous with the wire members of the frame  102 . 
     In the depicted embodiment, the leaflet engagement members  140   a - b  terminate at free ends. Accordingly, the leaflet engagement members  140   a - b  point toward the inflow end portion  102   i  of the main body  106 , with the free ends of the leaflet engagement members  140   a - b  being the closest to the inflow end portion  102   i . This arrangement defines the space, groove, or slot receives and mechanically captures/holds a portion of a native leaflet to provide migration resistance for the valve  100 . 
     The depicted embodiment of the valve  100  includes an optional posterior arm  150 . The posterior arm  150  comprises a wire member (e.g., an elongated loop) that extends from the frame  102  and includes a free end  150   e  (which can also be said to be located at a distal end portion of the posterior arm  150 ). In some embodiments, the posterior arm  150  is a wire member that is constructed unitarily with wire members of the frame  120 . Hence, it can be said that the posterior arm  150  is a portion of the frame  120 . In the depicted embodiment, the covering  104  is attached to the posterior arm  150 , including the free end  150   e.    
     In the depicted embodiment, the posterior arm  150  extends from the inflow end portion  102   i  of the frame  102 . The posterior arm  150  extends in a direction that is the same as, or that is generally (e.g., +/−20°) parallel to, the direction in which the posterior flap  130  extends. In some embodiments, the posterior arm  150  extends from the mid-body portion  102   m  of the frame  102 . The location of the free end  150   e  is within a transverse plane (e.g., taken perpendicular to the axis  101 ) that intersects the mid-body portion  102   m  of the frame  102  or the inflow end portion  102   i  of the frame  102 . 
     The posterior arm  150  provides additional anchorage and migration resistance for the valve  100 . As depicted in  FIG.  7   , the free end  150   e  of the posterior arm  150  abuts against an anatomical structure when the valve  100  is engaged in a native tricuspid valve  10 . In some cases, the free end  150   e  of the posterior arm  150  abuts against an interior wall of an inferior vena cava, or coronary sinus, or the right atrium, or another anatomical structure. Where it abuts can be largely a function of the variable anatomy from patient to patient. The migration resistance provided by the posterior arm  150  can be particularly advantageous during diastole when the occluder  110  is open to allow blood flow from the right atrium to the right ventricle via the occluder  110 . 
     Referring also to  FIG.  9   , in some embodiments the frame  102  can include an anterior arm  160 . The anterior arm  160  may also be covered similarly to the posterior arm  150 . The anterior arm  160  comprises a wire member (e.g., an elongated loop) that extends from the frame  102  and includes a free end  160   e  (which can also be said to be located at a distal end portion of the posterior arm  160 ). In some embodiments, the anterior arm  160  is a wire member that is constructed unitarily with wire members of the frame  120 . Hence, it can be said that the anterior arm  160  is a portion of the frame  120 . In the depicted embodiment, the covering  104  is attached to the anterior arm  160 , including the free end  160   e.    
     In the depicted embodiment, the anterior arm  160  extends from the inflow end portion  102   i  of the frame  102 . The anterior arm  160  extends in an anterior direction away from the axis  101  (e.g., a direction that is generally the same as the direction in which the anterior flaps  120   a - b  extend). In some embodiments, the anterior arm  160  extends from the mid-body portion  102   m  of the frame  102 . The location of the free end  160   e  is within a transverse plane (e.g., taken perpendicular to the axis  101 ) that intersects the mid-body portion  102   m  of the frame  102  or the inflow end portion  102   i  of the frame  102 . 
     The anterior arm  160  provides additional anchorage and migration resistance for the valve  100 . The free end  160   e  of the anterior arm  160  abuts against an anatomical structure when the valve  100  is engaged in a native tricuspid valve  10 . In some cases, the free end  160   e  of the anterior arm  160  abuts against an interior wall of a right atrial appendage or another anatomical structure. Where the anterior arm  160  lands relative to the anatomy can vary based on patient to patient variability. The migration resistance provided by the anterior arm  160  can be particularly advantageous during diastole when the occluder  110  is open to allow blood flow from the right atrium to the right ventricle via the occluder  110 . 
     Some embodiments of the valve  100  include the posterior arm  150 , but not the anterior arm  160 . Other embodiments of the valve  100  include the anterior arm  160 , but not the posterior arm  150 . Still other embodiments of the valve  100  include both the posterior arm  150  and the anterior arm  160 . 
       FIG.  10    schematically illustrates a transverse plane view of a native tricuspid valve  10 . The native tricuspid valve  10  includes the annulus  12 . The RVOT extends away from the native tricuspid valve  10  along an arcuate path. 
       FIG.  11    schematically illustrates a top view of the valve  100 . The valve  100  includes the main body  106 , the occluder  110 , the septal anterior flap  120   a , the lateral anterior flap  120   b , the posterior flap  130 , and the posterior arm  150 . 
       FIG.  12    schematically illustrates the valve  100  engaged in the anatomy of the native tricuspid valve  10  (that is also illustrated in  FIG.  10   ). In this illustration, it can be seen how the septal anterior flap  120   a  and the lateral anterior flap  120   b  extend into the RVOT. Moreover, it can be seen that an edge of the lateral anterior flap  120   b  abuts against and extends along a lateral wall  14  of the RVOT. 
       FIG.  13    schematically illustrates a cross-sectional view of the RVOT and distal end portions of the anterior flaps  120   a - b . This cross-sectional view is taken along the cutting plane  13 - 13  shown in  FIG.  12   . It can be seen that the edge of the lateral anterior flap  120   b  abuts against and engages with the anatomical topography of the lateral wall  14  of the RVOT. The interfacing relationship between the lateral anterior flap  120   b  and the lateral wall  14  of the RVOT provides anchorage and migration resistance of the valve  100  relative to the native tricuspid valve  10 . For example, there is a frictional migration resistance aspect provided by the normal forces exerted by the edge of the lateral anterior flap  120   b  against the lateral wall  14  of the RVOT. In addition, in some embodiments there is supplementary migration resistance provided because the edge of the lateral anterior flap  120   b  can seat against certain anatomical topographical features of the lateral wall  14  of the RVOT. In such a case, the lateral wall  14  physically supports the lateral anterior flap  120   b  and resists movement of the valve  10  relative to the anatomy of the native tricuspid valve  10  and RVOT. The interfacing relationship between the lateral anterior flap  120   b  and the lateral wall  14  of the RVOT provides anchorage and migration resistance of the valve  100  relative to the native tricuspid valve  10  that is particularly beneficial during diastole when the occluder  110  is open to allow blood flow from the right atrium to the right ventricle via the occluder  110 . 
     Referring again to  FIG.  10   , the shape of the annulus  12  of many tricuspid valves is not circular. Often, as depicted here, shape of the annulus  12  is oblong or ovoidal (oval shaped). That is, the distance between the posterior and anterior regions of the annulus  12  is longer than the distance between the septal and lateral regions of the annulus  12 . Accordingly, it can be said that the annulus  12  defines a major diameter  16  between the posterior and anterior regions, and a minor diameter  18  between the septal and lateral regions of the annulus  12 . 
     Also referring again to  FIG.  12   , in this embodiment of the valve  100 , the main body  106  has an ovular outer cross-sectional shape. In contrast, the occluder  110  within the main body  106  has a circular cross-sectional shape. The oval shaped main body  106  of the valve  100  has a major diameter  108  and a minor diameter  109 . The anterior flaps  120   a - b  and the posterior flap  130  extend from the main body  106  along a direction that is transverse to the major diameter  108  of the oval shaped main body  106 . In some embodiments, the anterior flaps  120   a - b  and/or the posterior flap  130  extend from the main body  106  substantially orthogonally or perpendicularly (e.g., 90°+/−5°, 90°+/−10°, 90°+/−15°, or 90° 30+/−20°,) to the major diameter  108  of the oval shaped main body  106 . 
     In some embodiments, as depicted in  FIG.  12   , the main body  106  is smaller than the full size/area of the annulus  12 . Accordingly, the anterior flaps  120   a - b  can be used to fill up the internal area defined the annulus  12  that is not occupied by the main body  106 . The occluder  110  occupies a circular cross-sectional area that is smaller than the cross-sectional area main body  106 , which is adequate for the hemodynamics of the blood flow between the atrium and the ventricle. In some embodiments, the percentage of the internal area defined by the annulus  12  that is occupied by the main body  106  is about 50% (with the remaining about 50% of the area of the annulus  12  being covered by the anterior flaps  120   a - b ). In some embodiments, the percentage of the area of the annulus  12  that is occupied by the main body  106  is in a range of about 50% to 60%, or 55% to 65%, or 60%, to 70%, or 65% to 75%, or 70% to 80%, or 75% to 85%, or 60% to 80%, without limitation, with the anterior flaps  120   a - b  covering the remainder of the area of the annulus  12 . In some embodiments, the anterior flaps  120   a - b  cover at least 50%, or at least 40%, or at least 30%, or at least 20%, or at least 10%, or at least 5% of the internal area defined by the annulus  12 . 
     The fact that the anterior flaps  120   a - b  cover at least a portion of the area defined within the annulus  12  can be beneficial for additional reasons. For example, if, at some point in the future after the valve  100  has been implanted in the annulus  12 , a pacemaker lead needs to be passed through the annulus  12 , then a location on the anterior flaps  120   a - b  can be punctured to allow the pacemaker lead to pass through the anterior flaps  120   a - b . The puncture can be at the open passage  122 , or at another location of the anterior flaps  120   a - b . The ability to pass a pacemaker lead through the anterior flaps  120   a - b  is advantageous because doing so does not affect the functionality of the occluder  110 . This is advantage is made possible by the fact that the anterior flaps  120   a - b  cover at least a portion of the area of the annulus  12 . 
     Since, as depicted in the example of  FIG.  12   , in some cases a portion of the oval shaped annulus  12  is covered by the anterior flaps  120   a - b , the main body  106  need not be circular, and can be constructed to have various types of cross-sectional shapes. An oval shape (as shown) may be preferable in some cases, as it can be radially compressed well for fitting in a low-profile delivery catheter because it can have a smaller perimeter due to the minor diameter  109  of the main body  106  being shorter than the major diameter  108 . If, for example, the main body  106  had a circular cross-sectional shape with a diameter equal to the major diameter  108 , the main body  106  could not be radially crushed/compressed to as small of a size as the depicted oval shaped main body  106 . Hence, a larger delivery sheath would be required if the main body  106  was circular (as compared to ovular as shown). 
     Interestingly, in the example depicted in  FIG.  12   , while both the annulus  12  of the tricuspid valve  10  and the main body  106  of the valve  100  are oblong or oval shaped, the orientations of their major and minor diameters are about 90° (e.g., 90°+/−10°) offset in relation to each other when the valve  100  is implanted in the tricuspid valve  10 . That is, the major diameter  108  of the oval shaped main body  106  is substantially parallel (e.g., +/−10°) relative to the minor diameter  18  of the annulus  12 . Moreover, the minor diameter  109  of the oval shaped main body  106  is substantially parallel (e.g., +/−10°) relative to the major diameter  16  of the annulus  12 . These geometric relationships are beneficial because the annulus  12  is fully occluded by the valve  100  and the diameter of the radially compressed delivery configuration of the valve  100  can be reduced (as compared to having the main body  106  filling a larger area of the annulus  12 ). 
     Again, it is evident in  FIG.  12    that the opening defined by the native annulus  12  is not completely filled by the main body  106 . Instead, the laterally-extending first and second anterior flaps  120   a - b  help to cover and fluidly seal the native tricuspid valve opening which is not circular in this example (e.g., with the native valve opening being oblong, or irregularly shaped). In other words, in combination with the main body  106  of the valve  100 , the first and second anterior flaps  120   a - b  (and the laterally-extending posterior anchoring flap  130  in some cases) help to cover and fluidly seal the native tricuspid valve opening which is not circular in some cases. In addition, terminal end portions of the first and second anterior flaps  120   a - b  extend into the RVOT to provide anchoring and migration resistance. Accordingly, the first and second anterior flaps  120   a - b  perform both sealing and anchorage. 
     In some cases, the shape of a patient&#39;s native annulus  12  is generally circular. In such a case, the valve  100  can still provide much of the benefits described above. For example, the main body  106  can still have an oblong or oval-shaped outer cross-sectional shape that occupies less than the full circular area of the native annulus  12  (with the first and second anterior flaps  120   a - b  occupying the remainder). In that case, the valve  100  is implanted in the native annulus  12  such that the central axis  101  of the occluder  110  is laterally offset (e.g., in the posterior direction) from the geometric center of the generally circular native annulus  12 . In addition, the major diameter  108  of the main body  106  can be shorter than the diameter of the native annulus  12 . For example, in some embodiments the length of the major diameter  108  of the main body  106  is about 60% to 80% of the diameter of the native annulus  12 , or about 70% to 90% of the diameter of the native annulus  12 , or about 80% to 95% of the diameter of the native annulus  12 , without limitation. 
       FIG.  14    illustrates a longitudinal plane cross-section view (e.g., approximately parallel to the central axis of the annulus  12 ) near an anterior portion of the native tricuspid valve annulus  12 . This view is from the interface between the RVOT and the native tricuspid valve annulus  12 , looking toward the right atrium and right ventricle. In this view, it can be seen that the anterior annulus  12  is curved. 
       FIG.  15    shows an anterior end view of the frame  102  of the valve  100  (without the covering  104  in this example). The first and second anterior flaps  120   a - b  are in the foreground in this view, and the main body  106  is in the background. 
     A heavy line  121  has been superimposed on  FIG.  15    to represent the cross-sectional shape of the first and second anterior flaps  120   a - b  (when the covering  104  is attached to the frame  102 ). It can be seen that the cross-sectional shape of the first and second anterior flaps  120   a - b  (taken perpendicularly to the direction in which the first and second anterior flaps  120   a - b  extend from the main body  106 ) is curved or arcuate. The arc extends from the outflow end portion  102   o  of the frame  102  toward the inflow end portion  102   i , with the middle of the arc being the closest point of the arc to the inflow end portion  102   i.    
     The curved or arcuate cross-sectional shape of the first and second anterior flaps  120   a - b  is beneficial because, as described in reference to  FIG.  14   , the anterior portion of the native tricuspid valve annulus  12  with which the first and second anterior flaps  120   a - b  interface is also curved. Accordingly, a good sealing interface between the arced first and second anterior flaps  120   a - b  and the arced antenor portion of the native tricuspid valve annulus  12  is created by these complimentary curved shapes. This sealing arrangement between the arced first and second anterior flaps  120   a - b  and the native tricuspid valve annulus  12  can be beneficial for mitigating paravalvular leaks when the valve  100  is engaged with the native tricuspid valve  10 . 
     As shown in  FIG.  15   , in the depicted embodiment the arcuate cross-sectional shape of the first and second anterior flaps  120   a - b  is at least partially facilitated by the configuration of frame portions  128   a  and  128   b  (also visible in  FIG.  9   ). The frame portions  128   a  and  128   b  constitute interior parts of the outer edges of the first and second anterior flaps  120   a - b . The frame portions  128   a  and  128   b  are arranged at a non-zero angle in relation to the central axis  101  so as to help define the arcuate cross-sectional shape of the first and second anterior flaps  120   a - b  that is represented by the heavy line  121 . In some embodiments, the angle between the frame portions  128   a  and  128   b  and the central axis  101  is between 20° to 50°, or between 30° to 60°, or between 40° to 70°, without limitation. The frame portions  128   a  and  128   b  near the outer edges of the first and second anterior flaps  120   a - b  perform particularly advantageously to create good seals between the first and second anterior flaps  120   a - b  and the anterior portion of the native tricuspid valve annulus  12 , because paravalvular leaks are particularly prone to occur in those edge areas. 
       FIGS.  17  and  18    illustrate an example prosthetic heart valve deployment system  200  (or simply “deployment system  200 ”). The deployment system  200  includes a control handle  210 , an outer sheath catheter  220 , a middle deflectable catheter  230 , and an inner control catheter  240 . The outer sheath catheter  220  defines a first lumen. The middle deflectable catheter  230  is slidably disposed in the first lumen and defines a second lumen. The inner control catheter  240  is slidably disposed in the second lumen. 
     The inner control catheter  240  includes a curved portion  242 . The curved portion  242  is elastically deformable. That is, while the curved portion  242  is located within the confines of the first lumen of the outer sheath catheter  220 , the curved portion  242  is essentially linear (or at least more linear than when the curved portion  242  is radially unconstrained). When the curved portion  242  of the inner control catheter  240  is distally expressed out (either by pushing the inner control catheter  240  distally or by pulling the outer sheath catheter  220  proximally) from the confines of the first lumen of the outer sheath catheter  220 , the curved portion  242  then naturally elastically reconfigures to exhibit a pronounced curve (e.g., as shown in  FIG.  18   ). Thus, it can be said that the natural shape of the inner control catheter  240  includes the curved portion  242  that defines an interior angle θ. In some embodiments, the interior angle θ can be between 130° and 160°, or between 120° and 150°, or between 110° and 140°, or between 100° and 130°, or between 90° and 120°, or between 80° and 110°, or between 80° and 100°, without limitation. In some embodiments, the interior angle θ can be less than 160°, or less than 150°, or less than 140°, or less than 135°, or less than 130°, or less than 120°, or less than 110°, or less than 100°, or less than 90° without limitation. 
     The middle deflectable catheter  230  includes a selectively deflectable distal end portion  232  with at least one plane of deflection. In some embodiments, the selectively deflectable distal end portion  232  is deflectable in two planes. In some embodiments, the middle deflectable catheter  230  includes two or more separate selectively deflectable portions that are in same planes or in different planes. 
     In the depicted embodiment, the selectively deflectable distal end portion  232  is deflectable in a same plane as the plane of the curved portion  242  of the inner control catheter  240 . Accordingly, when the selectively deflectable distal end portion  232  of the middle deflectable catheter  230  is deflected, the curvature of the combination of the middle deflectable catheter  230  and the inner control catheter  240  in relation to the axis of the outer sheath catheter  220  is increased beyond that of the interior angle θ alone. In some embodiments, the combined curvature of the middle deflectable catheter  230  and the inner control catheter  240  in relation to the axis of the outer sheath catheter  220  can define an interior angle between 90° and 110°, or between 80° and 100°, or between 700 and 90°, or between 60° and 80°, or between 50° and 70°, or between 30° and 60°, or between 0° and 30°, without limitation. This high degree of curvature can be beneficial during deployment of a prosthetic valve (such as the valve  100 ) using the deployment system  200 , as described further below. 
     The inner control catheter  240  can also include mechanical features for releasably coupling with a prosthetic valve (such as the valve  100 ). For example, in the depicted embodiment, the inner control catheter  240  includes one or more control wires and/or release pins  244  that can releasably couple the valve  100  to the inner control catheter  240  in a low profile delivery configuration. 
       FIG.  19    shows a schematic illustration of the valve  100 .  FIG.  20    schematically shows the valve  100  coupled to the inner control catheter  240  and located within the first lumen defined by the outer sheath catheter  220 . The distal tip of the middle deflectable catheter  230  is also visible. In this arrangement, the valve  100  is radially compressed to a low-profile delivery configuration while within the outer sheath catheter  220 . In some embodiments, the valve  100  (or portions thereof are wrapped or folded around the inner control catheter  240 . For example, in some embodiments the anterior flaps  120   a - b  are wrapped around the inner control catheter  240 . The valve  100  can self-expand as its emergence from the outer sheath catheter  220  takes place (e.g., by the manual retraction of the outer sheath catheter  220  relative to the middle deflectable catheter  230  and the inner control catheter  240 ). 
     In some embodiments, when the valve  100  is in its collapsed delivery configuration within the outer sheath catheter  220 , the portions of the valve  100  are arranged relative to each other as follows. The first and second anterior flaps  120   a - b  (which can be wrapped on each other) are distal-most. The occluder portion (or valve core)  110  with the flexible leaflets is proximal-most within the outer sheath catheter  220 . The posterior anchoring flap  130  is arranged between the distal-most first and second anterior flaps  120   a - b  and the proximal-most occluder portion  110 . 
     The valve  100  can be releasably coupled to the inner control catheter  240  using the one or more control wires and/or release pins  244  ( FIG.  18   ). In some embodiments, a first control wire is releasably coupled to a proximal end portion of the main body  106 , a second control wire is releasably coupled to a distal end portion of the main body  106 , and a third control wire is releasably coupled to the posterior flaps  120   a - b . The control wires can be tensioned to draw and maintain the associated portion of the valve  100  radially inward to be snug against the inner control catheter  240 . During deployment of the valve  100 , the control wires can be individually relaxed to allow the associated portion of the valve  100  to expand elastically toward its natural expanded shape. 
     Still referring to  FIG.  20   , in this delivery configuration the curved portion  242  of the inner control catheter  240  is being constrained in an essentially linear configuration by the outer sheath catheter  220 . However, when the inner control catheter  240  is expressed from the outer sheath catheter  220  (or as the outer sheath catheter  220  is pulled proximally relative to the inner control catheter  240 ), the curved portion  242  will become unconstrained and will elastically deflect to its natural curved configuration (e.g., as shown in  FIG.  18   ). The curved configuration of the curved portion  242  is beneficial for the deployment process of the valve  100  into engagement with a native tricuspid valve  10 , as described further below. 
       FIGS.  21 - 30    illustrate a series of steps for deploying a prosthetic heart valve (such as the heart valve  100  described herein in any of its variations) using the heart valve deployment system  200 . These figures illustrate a trans-jugular vein approach to the native tricuspid valve  10  (via the superior vena cava). 
       FIG.  21    shows a distal end portion of the deployment system  200  emerging into the right atrium via the superior vena cava. The deployment system  200  is being advanced over a guidewire that was installed previously. The valve  100  (not visible) is within the outer sheath catheter  220 . 
       FIG.  22    illustrates the valve  100  (while the valve  100  is releasably coupled to the inner control catheter  240 ) after the withdrawal of the outer sheath catheter  220  and/or the advancement of the inner control catheter  240  and the middle deflectable catheter  230 . At this stage, the curved portion  242  (not visible under the valve  100 ) has become unconstrained and has elastically deflected to its natural curved configuration. The natural curved configuration of the curved portion  242  facilitates the inner control catheter  240  to make a relatively tight turn within the right atrium to advance from the vena cava and through the annulus  12  of the native tricuspid valve  10  as depicted. 
       FIGS.  23  and  24    illustrate further advancement of the valve  100  (while the valve  100  is still releasably coupled to the inner control catheter  240 ). In these images, the middle deflectable catheter  230  is being deflected (by a first amount in  FIG.  23    and a greater amount in  FIG.  24   ). The deflection of the middle deflectable catheter  230  adds to the curvature of the inner control catheter  240  to enable the distal end portion of the inner control catheter  240  to become directed toward the RVOT after passing through the annulus  12  (as shown in  FIG.  24   ). 
       FIGS.  25  through  27    illustrate the release process of the portions of the valve  100  from the inner control catheter  240 . As the portions of the valve  100  are released, those portions become engaged in the targeted native anatomical locations. The control wires and/or release pins for the anterior flaps  120   a - b  and the posterior flap  130  are released (as best seen in  FIG.  26   ). In response, the anterior flaps  120   a - b  deploy into the RVOT and the posterior flap  130  deploys to the posterior area of the tricuspid valve  10  just inferior to the annulus  12 . In addition, as the posterior flap  130  deploys, the one or more leaflet engagement members  140  engage with and capture/hold a portion of the native leaflet (e.g., the posterior leaflet  11   p  and/or the septal leaflet  11   s ) to provide migration resistance for the valve  100 . At this stage, the posterior arm  150  and/or the anterior arm  160  ( FIGS.  6 - 9   ) can also be deployed if the valve  100  includes a posterior arm  150  and/or an anterior arm  160 .  FIG.  27    shows the release of control wires that are coupled to the main body  106 . In response, the main body  106  radially expands into contact and engagement with the annulus  12 . 
       FIGS.  28  through  30    illustrate withdrawal of the deployment system  200 . When the control wires are disengaged from the valve  100 , the inner control catheter  240  and the middle deflectable catheter  230  can then be withdrawn, leaving the valve  100  engaged with the anatomy in and around the native tricuspid valve  100 . 
       FIG.  31    illustrates another example prosthetic heart valve  300 . The valve  300  is similar to the valve  100  described above, but is modified to be better suited for trans-femoral delivery (via the inferior vena cava) to the native tricuspid valve  10 . 
     The valve  300  includes an ovular main body  306  that contains a circular occluder  310  that defines a central axis  301 . The occluder  310  extends between an inflow end and an outflow end portion of the main body  306 , and includes valve leaflets in an arrangement that: (i) allows blood flow through the occluder  310  in a direction from the inflow end portion toward the outflow end portion along a central axis  301  of the occluder  310  and (ii) prevents blood flow through the occluder  310  in a direction from the outflow end portion toward the inflow end portion. The valve  300  also includes a first anterior flap  320   a  extending from the outflow end portion of the main body  306  in a first direction that is transverse to the central axis  301 , and a second anterior flap  320   b  also extending from the outflow end portion in the first direction. The valve  300  also includes a first posterior flap  330   a  extending from the outflow end portion of the main body  306  in a second direction that is opposite of the first direction, and a second posterior flap  330   b  also extending from the outflow end portion in the second direction. A passageway  332  (e.g., for a pacemaker lead as described above) is defined between the first and second posterior flaps  330   a - b . In contrast to the valve  100 , the first and second posterior flaps  330   a - b  of the valve  300  extend from the outflow end portion of the main body  306  farther (a greater distance) than the first and second anterior flaps  320   a - b . This arrangement biases the main body  306  toward the anterior portion of the annulus  12  (refer to  FIG.  10   ), which is different from the valve  100  which is biased toward the posterior portion of the annulus  12  (refer to  FIG.  12   ). 
       FIGS.  32 - 37    schematically illustrate a series of steps for deploying the heart valve  300  (as described herein in any of its variations) into the heart  1  using the heart valve deployment system  200  (e.g., refer to  FIGS.  17  and  18   ). These figures illustrate a trans-femoral vein approach to the native tricuspid valve  10  (via the inferior vena cava; “IVC”). 
       FIG.  32    illustrates the advancement of the deployment system  200  toward the right atrium (“RA”) via the IVC. The outer sheath catheter  220  (containing the heart valve  300  in its low-profile delivery configuration) can be advanced over a previously placed guidewire that extends into the right ventricle (“RV”) via the native tricuspid valve  10 . 
       FIG.  33    illustrates the emergence in the RA of the heart valve  300  from the outer sheath catheter  220  (e.g., by pulling the outer sheath catheter  220  proximally and/or by distally advancing the middle deflectable catheter  230  and inner control catheter  240 ). 
       FIGS.  34  and  35    illustrate the advancement of the heart valve  300  into position for engagement with the native tricuspid valve  10 . To accomplish this, the middle deflectable catheter  230  and inner control catheter  240  are both curved. That is, the inner control catheter  240  is naturally curved because of its curved portion  242 , and the middle deflectable catheter  230  is selectively deflected by a clinician operator who is performing the procedure. 
       FIG.  36    illustrates the release of the heart valve  300  from the inner control catheter  240 , and the resulting expansion/deployment of the heart valve  300  into engagement at the location of the native tricuspid valve  10 . The release of the various components/regions of the heart valve  300  can be performed in a controlled manner by manual manipulation of the one or more control wires and/or release pins  244  ( FIG.  18   ) by the clinician operator. The release of the heart valve  300  from the inner control catheter  240  results in the expansion of the main body  306 , the anterior flaps  320   a - b , and the posterior flaps  330   a - b  into engagement with the anatomy of the native tricuspid valve  10 , the RV, and the RVOT. 
     Lastly,  FIG.  37    illustrates the implanted heart valve  300  in engagement with the heart  1  and functioning as a prosthetic tricuspid valve between the RA and the RV. The deployment system  200  and guidewire have been withdrawn. It can be seen here (and in the top view of  FIG.  31   ) that the heart valve  300  is positioned such that the main body  306  is positionally biased toward the anterior portion of the annulus  12  (refer to  FIG.  10   ), which is adjacent the RVOT. Accordingly (and as shown in  FIG.  31   ), the laterally-extending first and second posterior flaps  330   a - b  help to cover and fluidly seal the native tricuspid valve opening within the annulus  12 , which is not circular in this example (e.g., with the native valve opening being oblong, oval, or irregularly shaped). In other words, in combination with the main body  306  of the valve  300 , the first and second posterior flaps  330   a - b  (and, in some cases, the laterally-extending anterior anchoring flaps  320   a - b  to a lesser extent) help to cover/occlude and fluidly seal the native tricuspid valve opening which is not circular in some cases. In addition, the end portions of the first and second posterior flaps  330   a - b  extend into engagement with the posterior shelf  11  ( FIG.  4   ) and/or with the wall of the RV just inferior to the annulus  12  to provide anchoring and migration resistance. Accordingly, the first and second posterior flaps  330   a - b  perform both sealing and anchorage. 
       FIGS.  38 - 40    illustrate the frame  102  that can be used in some embodiments of the prosthetic heart valves described herein. The frame  102  has a cellular construction that provides mechanical support for the shape and structures of the prosthetic heart valves. In some embodiments, the frame  102  is made from nitinol (NiTi), stainless steel, cobalt chromimum, MP35N, titanium, polymeric materials, other biocompatible materials, or any combination thereof. Some or all parts of the frame  102  may be covered (e.g., by the covering  104  described above). In some embodiments, the frame  102  can be made of a laser cut, expanded, and shape-set material. The frame  102  is self-expanding in some embodiments. In some embodiments, the precursor material is tubular NiTi, a NiTi sheet, or other suitable types of precursor materials. 
     In this example, the frame  102  includes the optional posterior arm  150  with the free end  150   e . The posterior arm  150  can also be referred to as a “diastolic anchoring tab,” because the posterior arm  150  helps to prevent migration of the prosthetic heart valve toward the right ventricle during diastole. In this example, the frame  102  does not include the anterior arm  160  (e.g., see  FIG.  9   ). However, in some embodiments the anterior arm  160  is included as part of the frame  102 . 
     In this example, the frame  102  does not include the frame portions  128   a  and  128   b  (e.g., see  FIG.  9   ). However, in some embodiments the frame portions  128   a  and  128   b  are included as part of the frame  102 . 
     As best seen in  FIG.  40   , the frame  102  includes an inflow end portion  102   i  and an outflow end portion  102   o . In the depicted embodiment, the cellular structure of the inflow end portion  102   i  and an outflow end portion  102   o  differ from each other. In particular, the size of the cells that make up the inflow end portion  102   i  are smaller than the size of the cells that make up the outflow end portion  102   o . For example, the cells of the inflow end portion  102   i  have a shorter longitudinal length (e.g., measured longitudinally parallel to the longitudinal axis  101 ) than the cells of the outflow end portion  102   o . Said another way, the cells of the outflow end portion  102   o  are longer when measured along the longitudinal direction of the frame  102  than the cells of the inflow end portion  102   i.    
     The differences in the sizes of the cells of the inflow end portion  102   i  as compared to the cells of the outflow end portion  102   o  causes the frame  102  to advantageously have different structural characteristics along the longitudinal length of the frame  102 . For example, the inflow end portion  102   i  of the frame  102  is structurally stiffer than the outflow end portion  102   o , particularly as related to radially directed forces. Conversely, the outflow end portion  102   o  of the frame  102  is structurally more flexible than the inflow end portion  102   i . Moreover, the structures of the anterior flaps  120   a - b  are very flexible because of the anterior flaps  120   a - b  are primarily made of large open areas within peripheral frame members (e.g., see  FIG.  39   ). 
     It can be advantageous for the inflow end portion  102   i  of the frame  102  to be structurally stiff. For example, such stiffness can help to maintain the circular cross-sectional shape of the occluder of the prosthetic valve (e.g., the occluder  110  shown in  FIGS.  6 - 8   ) while the heart muscle contracts to pump blood. Keeping such a circular cross-sectional shape of the occluder can serve to ensure that the leaflets of the occluder maintain their relative orientations in a predictable way. This can beneficially provide robust coaptation between the leaflets to mitigate the occurrence of regurgitation through the occluder, for example. 
     It can be advantageous for the outflow end portion  102   o  of the frame  102  and the anterior flaps  120   a - b  to be structurally flexible. For example, such flexibility can beneficially mitigate the amount of force from the frame  102  that is exerted onto the anatomy of the heart. In particular, having a flexible outflow end portion  102   o  and flexible anterior flaps  120   a - b  reduces or eliminates forces from the frame  102  from being applied to certain sensitive anatomical areas such as the AV node, the right coronary artery, and the annulus of the heart valve, to provide a few examples. 
       FIGS.  41 - 43    illustrate another example frame  102 ′ that can be used in some embodiments of the prosthetic heart valves described herein. This embodiment is different from the frame  102  in that the frame  102 ′ includes the frame portions  128   a  and  128   b  and does not include the posterior arm  150  (and also does not include an anterior arm  160 ). It should be understood that such features can be mixed and matched in any desired combination. 
     The frame  102 ′ shares the cell-size characteristics of the frame  102  as described above. That is, the cells that make up the inflow end portion  102   i  are smaller and stiffer than the cells that make up the outflow end portion  102   o . The cells of the anterior flaps  120   a - b  have the largest size (making them the most flexible portion of the frame  102 ′). 
     Alternative methods of achieving the variable stiffness characteristics described above are also contemplated. For example, the strut widths and/or thicknesses of different portions of the frame  102  could be different. 
     While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment in part or in whole. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described herein as acting in certain combinations and/or initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Although a number of implementations have been described in detail above, other modifications are possible. For example, the steps depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.