Abstract:
A prosthesis secures a replacement valve in a heart. The prosthesis includes a radially expandable inflow section and outflow section, and migration blocker rods. The inflow section has a tapered shape and is implanted within an atrium of a heart adjacent a native valve annulus. The outflow section couples to the inflow section, and is configured to be implanted through the native valve annulus and at least partially within a ventricle of the heart. The migration blocker rods extend circumferentially around at least a portion of the outflow section and hold native leaflets of the heart valve. In a contracted configuration, the prosthesis may be implanted through a catheter into the heart. In an expanded configuration, the tapered shape of the inflow section in the atrium cooperates with the migration blockers in the ventricle to hold the prosthesis against the native valve annulus.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is a divisional application of U.S. patent application Ser. No. 14/891,189 entitled, “TRANSCATHETER PROSTHETIC VALVE FOR MITRAL OR TRICUSPID VALVE REPLACEMENT,” filed on Nov. 13, 2015, which is a U.S. national stage filing under 35 U.S.C. §371 of International Application No. PCT/US2013/042275 filed on May 22, 2013 entitled “TRANSCATHETER PROSTHETIC VALVE FOR MITRAL OR TRICUSPID VALVE REPLACEMENT,” each of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to implantable prosthetic devices. The disclosure is particularly useful in prosthetic devices implantable by catheter for the treatment of mitral or tricuspid regurgitation. The cause of the regurgitation can be either functional or degenerative or any other reason. Certain disclosed embodiments may be used for other valvular lesions as well. 
       BACKGROUND 
       [0003]    Mitral Regurgitation is a valvular dysfunction that causes blood volume to flow during systolic (during left ventricular contraction) from the left ventricle to the left atrium as opposed to a healthy heart where this direction of flow is blocked by the mitral valve. The reverse flow during systolic causes a pressure rise in the left atrium. Maintaining a normal cardiac output results in an increased left ventricle pressure. 
         [0004]    Treating patients with MR or TR (mitral regurgitation or tricuspid regurgitation) could require valve replacement in order to reduce or eliminate the regurgitation. For many years, the acceptable common treatment was surgical repair or replacement of the native valve during open heart surgery. In recent years, a trans-vascular technique has been developed for introducing and implanting a prosthetic heart valve using a flexible catheter in a manner that is less invasive than open heart surgery. 
         [0005]    In the trans-vascular technique, the prosthetic is delivered to the target site (aortic valve, mitral valve, tricuspid valve, or other valve) through a catheter while the device is crimped to a low diameter shaft. When the prosthetic device is located in the correct position, it is expanded/deployed to a functional size. 
         [0006]    Advancing the catheter to the target site can be through: (a) The vascular system, where a catheter is advanced from the femoral vein/artery, or any other blood vessel that allows access to the target site; (b) Trans-apically where a catheter is advanced through a small incision made in the chest wall and then through the apex; or (c) Trans-atrially where a catheter is advanced through a small incision made in the chest wall and then through the left or right atrium. 
       SUMMARY 
       [0007]    A prosthesis secures a replacement valve in a heart. The prosthesis includes a radially expandable inflow section and outflow section and migration blocker rods. The inflow section has a tapered shape and is implanted within an atrium of a heart adjacent a native valve annulus. The outflow section couples to the inflow section and is configured to be implanted through the native valve annulus and at least partially within a ventricle of the heart. The migration blocker rods extend circumferentially around at least a portion of the outflow section and hold native leaflets of the heart valve. In a contracted configuration, the prosthesis may be implanted through a catheter into the heart. In an expanded configuration, the tapered shape of the inflow section in the atrium cooperates with the migration blockers in the ventricle to hold the prosthesis against the native valve annulus. 
         [0008]    Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A  illustrates a short axis view of a heart with four valves. 
           [0010]      FIG. 1B  illustrates a short axis view of mitral valve leaflets. 
           [0011]      FIG. 2A  illustrates a three-chamber view (long axis) of the heart. 
           [0012]      FIG. 2B  illustrates a two-chamber view (long axis) of the heart. 
           [0013]      FIG. 3  is an isometric view of a stent configured for placement in a native mitral or tricuspid valve according to one embodiment. 
           [0014]      FIG. 4  is a front view of the stent shown in  FIG. 3 . 
           [0015]      FIG. 5A  is a top view of a stent with an elliptical inflow and circular outflow according to one embodiment. 
           [0016]      FIG. 5B  is an isometric view of a stent with an elliptical inflow and a circular outflow according to one embodiment. 
           [0017]      FIG. 5C  is an isometric view of a stent with a circular inflow and a circular outflow according to one embodiment. 
           [0018]      FIG. 5D  is a top view of a stent with a circular inflow and a circular outflow according to one embodiment. 
           [0019]      FIG. 5E  is an isometric view of a stent with an elliptical inflow and an elliptical outflow according to one embodiment. 
           [0020]      FIG. 5F  is a top view of a stent with an elliptical inflow and an elliptical outflow according to one embodiment. 
           [0021]      FIG. 5G  is an isometric view of a stent with a circular inflow and an elliptical outflow according to one embodiment. 
           [0022]      FIG. 5H  is a top view of a stent with a circular inflow and an elliptical outflow according to one embodiment. 
           [0023]      FIG. 6A  is a front view of a stent having an outflow with one row of struts according to one embodiment. 
           [0024]      FIG. 6B  is a front view of a stent having an outflow with two rows of struts according to one embodiment. 
           [0025]      FIG. 7A  is a front view of migration blocking rods of a stent according to one embodiment. 
           [0026]      FIG. 7B  is a side view of the migration blocking rods of the stent shown in  FIG. 7A . 
           [0027]      FIG. 7C  is a bottom view of the migration blocking rods of the stent shown in  FIG. 7A . 
           [0028]      FIG. 8A  is a front view of migration blocking rods with ends close to each other according to one embodiment. 
           [0029]      FIG. 8B  is a front view of migration blocking rods with ends far from each other according to one embodiment. 
           [0030]      FIG. 9A  is a front view of a stent illustrating a curvature of the inflow (high profile inflow) according to one embodiment. 
           [0031]      FIG. 9B  is a front view of a stent illustrating a curvature of the inflow (low profile inflow) according to one embodiment. 
           [0032]      FIG. 10A  is an isometric view of a stent including migration rods with a leading mechanism at the distal end according to one embodiment. 
           [0033]      FIG. 10B  is an enlarged view of the leading mechanism at the distal end of the migration blocking rods shown in  FIG. 10A . 
           [0034]      FIG. 11A  is a front view of a stent including a migration locking mechanism with snapping according to one embodiment. 
           [0035]      FIG. 11B  is an enlarged view of the migration locking mechanism with snapping shown in  FIG. 11A . 
           [0036]      FIG. 11C  is an isometric enlarged view of the migration locking mechanism with snapping shown in  FIG. 11A . 
           [0037]      FIG. 12A  is an isometric view of a stent including barbs extending from the inflow section according to one embodiment. 
           [0038]      FIG. 12B  is an enlarged view of a barb shown in  FIG. 12A . 
           [0039]      FIG. 13A  is an isometric view of a stent including separate inflow and outflow sections according to one embodiment. 
           [0040]      FIG. 13B  is an isometric view of the separated inflow section shown in  FIG. 13A . 
           [0041]      FIG. 13C  is an isometric view of the separated outflow section shown in  FIG. 13A . 
           [0042]      FIG. 13D  is an enlarged isometric view of a connection area of the inflow and outflow sections shown in  FIG. 13A . 
           [0043]      FIG. 14A  illustrates a stent inside a heart in a three chamber view according to one embodiment. 
           [0044]      FIG. 14B  illustrates a stent inside a heart in a three chamber view according to one embodiment. 
           [0045]      FIG. 15  is a short axis view of a heart with a stent implanted therein according to one embodiment. 
           [0046]      FIG. 16A  is an enlarged view of a barb shown in  FIG. 16B  according to one embodiment. 
           [0047]      FIG. 16B  illustrates a locking mechanism between the migration blocker rods and the inlet according to one embodiment. 
           [0048]      FIG. 17  is a detailed cross-section view of migration blocker rods passing through the chordae according to one embodiment. 
           [0049]      FIG. 18  is a detailed cross-section view of a stent inside a heart, from a septal lateral perspective, according to one embodiment. 
           [0050]      FIGS. 19A, 19B, 20, and 21  show an example of a trans atrial approach for trans catheter implantation of a stent in the mitral position according to one embodiment. 
           [0051]      FIGS. 22A, 22B, 23, and 24  show an example of a trans apical approach for trans catheter implantation of a stent in the mitral position according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0052]    When used the singular form “a”, “an”, “the” refers to one or more than one, unless the context clearly dictates otherwise. 
         [0053]    As used herein, the term “includes” means “comprise” for example, a device that includes or comprises A and B contains A and B but can optionally contain C or other components other than A and B. A device that includes or comprises A and B may contain A or B, or A and B, and optionally one or more other components such as C. 
         [0054]    When the words “stent” and “frame” are used they refer to the same element (e.g., see stent  30  in  FIG. 3 ). 
         [0055]      FIG. 1A  shows a short axis section of the four valves in a heart: the aortic valve  7 , pulmonary valve  10 , tricuspid valve  9 , and mitral valve with anterior leaflet  5  and posterior leaflet  4 . In  FIG. 1B , there is an illustration of the mitral valve with posterior leaflet  4  sectioned into P 1 , P 2 , P 3  and anterior leaflet  5  sectioned into A 1 , A 2 , and A 3 . These sectioning methods are common knowledge and acceptable among those skilled in the art.  FIG. 1B  also shows a commissure  19  between A 1  and P 1  and a commissure  20  between A 3  and P 3 . 
         [0056]      FIG. 2A  is a three chamber view (long axis) of the heart. In this view, the left atrium  8 , left ventricle  2 , and right ventricle  1  are shown. The aortic valve  7  is at the end of the left ventricle outflow tract (LVOT)  13 . The mitral valve apparatus with mitral leaflets includes anterior leaflet  5  and posterior leaflet  4  attached to the chordae tandea  6  and papillary muscles  3 . This view is a section of the mitral valve through the A 2  (shown as area  22  in  FIG. 1B ) and P 2  (shown as area  21  in  FIG. 1B ) areas of the mitral leaflets. 
         [0057]      FIG. 2B  is a two chamber view (long axis) of the heart. In this view the left atrium  8  and left ventricle  2  are shown. The mitral valve apparatus includes the posterior mitral leaflet  4  attached to the chordae tandea  6  and papillary muscles  3 . This view is a section of the mitral valve through the commissures  19  and  20  of the mitral leaflets. 
         [0058]      FIG. 3  is a perspective view of a stent  30  configured for placement in a native mitral or tricuspid valve. The stent  30  in  FIG. 4  is a front view of the stent  30  shown in  FIG. 3 . In this embodiment, the stent  30  includes an upper section  31  (also referred to herein as “inflow section”  31 ) having an enlarged diameter (circumference) or flared end that tapers into a lower section  32  (also referred to herein as “outflow section”  32 ) of the frame having a reduced diameter (circumference). The upper section  31  and/or the lower section  32  may have different shape than circular. The stent  30  may have any combination of shapes  FIGS. 5A-5H  are only examples of the different shapes possible and other shapes may apply as well. Migration blocker rods  33  shown in  FIGS. 3 and 4  are separated rods, which after deployment lean against the native annulus and prevent migration of the stent into the atrium  8  shown in  FIG. 2A . The migration blocker rods  33  can have different lengths with different ends and additional features can be included, such as: A. a leading mechanism to ensure connectivity, after deployment, between different migration blocker rods; B. a locking mechanism between the rods; C. barbs to prevent rocking; and D. features that lock the migration blocker rods against the upper section  31  of the frame  30 . 
         [0059]    Inside the stent assembly, a prosthetic valve (not shown) may be added. The valve can be either bi-leaflet or tri-leaflet as long as it performs as required and can be made out of any tissue, polymer, or other material, as long as it is biocompatible. The stent  30  can be a self-expanding stent made of a shape memory material such as, for example, Nitinol. It can be cut from a tube, sheet, and/or a pattern that allows crimping and expanding like braided wires or any other technique that attaches wires. 
         [0060]    In other embodiments, the stent  30  can be a combination of a self-expanding stent and a balloon expandable stent. For example,  FIGS. 13A-13D  demonstrate an upper section  31  including a shape memory alloy that functions as a self-expandable frame, and a lower section  32  including a balloon expandable stent that requires balloon inflation for final deployment. The two sections can be attached in any way. For example, welding, mechanical attachment (as shown in  FIGS. 13A-13D ), and/or additional features that attach them are only some of the ways to attach the two sections of the stent assembly. 
         [0061]    The raw material of the stent  30  can be a metal of any kind that is biocompatible. The stent  30  may include a combination of two or more different materials. For example, the stent  30  may be one part stainless steel 316/316L and another part Nitinol. Other materials such as cobalt chrome may be used. The above materials are only examples, and other materials can be used as well. 
         [0062]    The design of the frame  30 , whether one part or more, is configured to allow crimping the prosthesis into a low profile shaft (equal to or less than 13 mm outer diameter (OD)). Patterns that allow this are known and crisscross patterns as shown for example in  FIGS. 3 and 4  for the outflow section  32  or braided stents are two examples, and other patterns may be applied as well. 
         [0063]    The migration blocker rods  33  of the stent  30  lean against the native annulus of the tricuspid or mitral valve, in general. When used in the mitral position, the migration blocker rods  33  may lean, in particular, against the mitral groove  14  shown in  FIG. 2A  in the posterior side and against the left fibrous trigon  18  and the right fibrous trigon  17  in the anterior side shown in  FIG. 1A . 
         [0064]    On the atrium side, the flared upper section  31  prevents any migration of the stent  30  into the ventricle  1  or  2  shown in  FIG. 2A  and helps provide sealing between the stent and the native apparatus by verifying good intimate contact and correlation between the inflow section geometry and the native shape of the mitral annulus and left atrium. 
         [0065]    The combination of the migration blocker rods  33  from the ventricle side of the native annulus and the upper section  31  flared stent from the atrium side of the annulus create a clamping effect on the annulus and provide a positive axial anchoring of the stent  30  to its target site. 
         [0066]    For the upper section  31 , according to certain embodiments, an elliptical shape allows reducing the inflow section projection and therefore reduces the area that faces high pressure during systole. This feature reduces the axial forces that the prosthesis faces and needs to be anchored against. At the same time, an elliptical shape assures continuous contact between the upper section  31  and the atrium and prevents any para-valvular leakage (PVL). Any other shape that will at the same time prevent PVL and minimize the projection of the inflow may also be used. 
         [0067]    The curvature that defines the transition zone and/or the inflow section profile may be configured to increase or decrease the clamping effect between migration blocker rods  33  and the inflow section  31 .  FIGS. 9A and 9B  show two examples and any other curvature that allows the upper section to be fixated in the atrium and the migration blocker rods to stay under the native annulus in the ventricle is acceptable. 
         [0068]    In the area of connection between the upper section  31  and lower section  32  of the stent  30  are attached migration blocker rods  33  which prevent the valve from migrating into the left atrium. The migration blocker rods  33  go in between the chordae under the native commissures  19  and  20  shown in  FIG. 1B  and lean against the mitral annulus from behind the native leaflets.  FIGS. 14A, 14B, 15, 16A, 16B, and 17  show the extraction of the migration blocker rods from the stent, passing through the chordae and turning around the native leaflets. At the final position, the rods  33  lean against the native annulus. 
         [0069]      FIGS. 5A-5H  represents different combinations of the inflow and outflow profiles. The inflow profile in the illustrated embodiments can be either circular  57  (as shown in  FIGS. 5C, 5D, 5G, and 5H ) or elliptical  54  (as shown in  FIG. 5A, 5B, 5E, and 5F ), or any other shape that fits the native anatomy of the atrium. The outflow profile can be either circular  58  (as shown in  FIGS. 5A, 5B, 5C and 5D ) or elliptical  59  (as shown in  FIGS. 5E, 5F, 5G and 5H ), or any other shape that fits to withhold a prosthetic valve inside, either bi leaflet or tri leaflet.  FIGS. 5A-5H  illustrate, by way of example, only four combinations out of many possible options for the design of the stent  30 . 
         [0070]    In  FIGS. 5A-5H , the circumference of the inflow section  31  and its upper end  55  can vary between about 225 mm to 90 mm. This large variation is due to the target population of the device, which some have a very large atrium. The circumferences of the outflow section  32  and its lower end  56  can vary between about 110 mm to 60 mm. This variation is to allow different sizes of valves inside the outflow according to the acceptable standards, if they exist, for the mitral and tricuspid position. The height of the stent may vary between about 20 mm to 60 mm, as long as it doesn&#39;t injure the left ventricle walls by the lower section  32  and lower end  56  and doesn&#39;t interfere with the flow from the pulmonary veins and/or cause any risk relative to the left appendage. The valve  52  (shown in  FIGS. 5A, 5C, 5F, and 5H ) can be either bi-leaflet or tri-leaflet as long as it performs as required and can be made out of any tissue, polymer, or other material as long as it is biocompatible. The stent  30  can be a self-expanding stent made of a shape memory material such as, for example, Nitinol. It can be cut from a tube, sheet, and/or a pattern that allows crimping and expanding like braided wires or any other technique that attaches wires as long as it performs well. 
         [0071]    In  FIGS. 5A and 5D , an illustrated tri leaflet valve  52  is mounted in the circular outflow section  32 . The valve  52  is configured such that the flow of blood goes substantially only in one direction and that substantially no back flow will occur through the valve according to the acceptable standards. 
         [0072]    The valve  52  can be composed from biological tissue such as pericardium or alternatively from a polymer, fabric, or the like. 
         [0073]    In other embodiments, such as shown in the  FIGS. 5F and 5H , the valve  52  in the outflow section  32  can be bi leaflet. 
         [0074]    In  FIGS. 6A and 6B , there is a front view of the stent  30  according to certain embodiments. It is illustrated as an example that the stent  30  can have any number of rows of struts (illustrated as “V” shaped structural supports), as long as the struts allow crimping into a catheter and deployment to the final configuration. The outflow section  32  can have either 1 (one) row of struts or more. In the illustrated embodiments, there is an example of an outflow section  32  with 1 (one) row of struts in  FIG. 6A , and an embodiment of an outflow section  32  with 2 (two) rows of struts in  FIG. 6B . This is not limiting and more rows can be added. In certain embodiments, the inflow section  31  also includes expandable struts. For example, the inflow section  31  may be designed in a similar manner as that of the outflow section  32  with a criss-cross pattern and/or any number of rows of struts, as long as the expandable struts allow crimping and expanding of the inflow section  31  to its different configurations. 
         [0075]      FIGS. 7A, 7B, and 7C  illustrate the migration blocker rods  33  from three different views.  FIG. 7A  illustrates the migration blocker rods  33  in stent  30  from a front view,  FIG. 7B  illustrates the migration blocker rods  33  in stent  30  from a side view, and  FIG. 7C  illustrates the migration blocker rods  33  in stent  30  from a bottom view. The rods  33  are configured to be attached to the stent  30  either to the inflow section  31  or to the outflow section  32  at the area where these sections are attached to each other, and to provide axial fixation of the stent  30  at the target site. 
         [0076]    The migration blocker rods  33  around the posterior leaflet  4  are configured to lean against the mitral groove  14  and prevent any migration and axial movement in the posterior side. 
         [0077]    The migration blocker rods  33  around the anterior leaflet  5  are configured to lean against the left and right fibrous trigons  17  and  18  and prevent any migration and axial movement in the anterior side. 
         [0078]    There are one, two, or more migration blocker rods  33  around the posterior leaflet  4 . There are another one, two, or more migration blocker rods  33  around the anterior leaflet  5 . The quantity of the migration blockers can vary from two to multiple rods and in the certain illustrated embodiments there are four of them only for visualization and as example. In other embodiments, the quantity of migration blocker rods  33  can be any number from two to eighteen. 
         [0079]    The migration blocker rods  33  can have ends separated from one another, can meet each other behind the leaflets  4  and  5 , may include a leading mechanism behind the leaflet to ensure the attachment of the rods to one another and may include a locking mechanism that prevents them from separating after deployment. 
         [0080]    The migration blocker rods  33  can be in different lengths with different ends  81  and additional features can be added on them. The ends  81  of the migration blocker rods  33  can be seen in  FIGS. 8A and 8B . It can be seen that the distance between them can vary from zero, at minimum (they can touch each other), to, at maximum, half the circumference of the outflow section. In the later, the length of the rods  33  is very short and the point of leaning against the annulus is under the commissures  19  and  20  in  FIG. 1B . 
         [0081]    In  FIGS. 10A and 10B , there is a leading mechanism  100  at the end  81  of the migration blocker rods  33  that allows connecting two migration blocker rods  33  that come from opposite commissures  19  and  20 . The leading mechanism  100  allows two different migration blocker rods  33  to meet and attach to each other. Due to the nature of beating heart procedures and no direct visualization (only through X-ray and ultrasound), it may be useful to have such a mechanism  100  that allows leading one rod  33  into the other to assure that the two can be connected. The illustrated mechanism  100  is only one example. Others can be designed and might include wire, suture, metallic, and/or plastic members, etc. 
         [0082]    In  FIGS. 11A, 11B, and 11C , there is a snapping mechanism  110  at the end  81  of the migration blocker rods  33  that allows connecting two migration blocker rods  33  that come from opposite commissures  19  and  20  and lock them one into the other. Once two migration blocker rods  33  are attached and locked the stent is firmly secured in place and the rods  33  can&#39;t be crimped back to the crimped configuration unless the snap mechanism  110  is released. The snap illustrated in  FIGS. 11A, 11B, and 11C  is one example for such mechanism and others with additional members as metallic and/or plastic parts, wire, suture can be added. 
         [0083]      FIGS. 12A and 12B  illustrate migration blocker rods  33  that include barbs  120  configured to penetrate the mitral annulus from the ventricle side and ensure no relative movement between the frame  30  and the mitral annulus. The barbs  120  that penetrated the mitral annulus can be locked into the inflow section of the frame from the atrium side or locked into an additional ring.  FIG. 12B  is a zoom on the isometric view of a barb that is part of a migration blocker rod  33  that penetrated through the annulus into the inflow section  31 . 
         [0084]    The migration blocker rods  33  can be cut from the same tube and heat treated to the final shape. The migration blocker rods  33  can be cut from different tube and be attached to the main frame differently using a direct attachment such as welding or with additional members such as sutures, metallic parts, etc. The migration blocker rods  33  can be crimped distally to the main frame, proximally to the main frame and on top of it. The migration blocker rods  33  might be covered with a fabric, soft tissue, and/or polymer to prevent any damage to the annulus apparatus. 
         [0085]      FIGS. 13A, 13B, 13C and 13D  illustrate a stent  30  that includes two different sections. The inflow section  31  is a self-expanding stent made from a shape memory alloy and functions as a self-expandable frame, and the outflow section  32  is a balloon expandable stent that requires balloon inflation for final deployment. 
         [0086]      FIG. 13A  is an isometric view of the two sections attached together through an attachment member  130 . The attachment member  130  can be part of the inflow section  31 , outflow section  32 , both the inflow section  31  and the outflow section  32 , and/or as an additional member. 
         [0087]      FIG. 13B  illustrates an example of an inflow section  31  made out of shape memory alloy where the migration blocker rods  33  are part of it. For example, inflow section  31  and the migration blocker rods  33  may be formed from the same piece of shape memory material. In other embodiments of the inflow section  31 , the migration blocker rods  33  can be omitted or designed differently. In addition or in other embodiments of the inflow section  31 , an attachment feature for connecting to the outflow section  32  can be added. An example of such a feature is a metallic flange that is cut from the frame and illustrated in the attached embodiments as attachment member  130 . 
         [0088]      FIG. 13C  illustrates an example of an outflow section  32  made out of an alloy such as stainless steel (StSt), such as StSt 316/StSt 316L. In other embodiments, the outflow section  32  can be made out of a self-expandable alloy, such as, a shape memory alloy, and might include the migration blocker rods  33 . In addition or in other embodiments of the outflow section  32 , an attachment feature for connecting to the inflow section  31  can be added. An example of such a feature is a metallic flange that is cut from the frame and illustrated in the attached embodiments as attachment member  130 . 
         [0089]      FIG. 13D  illustrates an enlarged view of the attachment feature  130  between the inflow section  31  and the outflow section  32 . In this embodiment, the attachment feature  130  includes two metallic flanges. One is part of the inflow section  31 , and one is part of the outflow section  32 . The two flanges can be attached together by snapping one to another, suturing them together, or any other attachment method. 
         [0090]      FIG. 14A and 14B  illustrate how the stent  30  may be positioned in the mitral valve. In  FIG. 14A , the section of the heart illustrates a two chamber view and the cross-section of the drawing passes through the mitral valve commissures. It can be seen that the stent  30  is behind the posterior leaflet  4 , the migration blocker rods  33  pop out from the commissures  19  and  20 , and the end  81  of the migration blocker rods  33  is in the P 2  section of the leaflet (area  21  in  FIG. 1B ). In  FIG. 14B , the section of the heart illustrates a three chamber view and the cross-section of the drawing passes through the A 2  and P 2  (areas  21  and  22  in  FIG. 1B ) of the native valve. It can be seen that the stent  30  is between the posterior leaflet  4  and anterior leaflet  5 , the migration blocker rods  33  pop out from the commissures area, and the ends  81  of the migration blocker rods  33  are located in the posterior side under the mitral groove  14  and under the left and right fibrous trigons ( 18  and  17  in  FIG. 1A ) in the anterior side. 
         [0091]      FIG. 15  illustrates the stent  30  in the mitral valve from a short axis view from the atrial side. The migration blocker rods  33  are located in the ventricle side under the mitral leaflets. 
         [0092]      FIGS. 16A and 16B  illustrate an additional feature that can be added to the migration blocker rods  33 . The barbs  120  are part of the migration blocker rods  33  and are designed in a way that after deployment they penetrate the mitral annulus and/or mitral leaflets and anchor the stent to the annulus. The barbs  120  can be an integral part of the migration blocker rods  33  or an additional member that is assembled on the barbs. The barbs  120  may be configured so that they have an opposite member or feature in the inflow section  31  in a way that after crossing the tissue they lock into the inflow section. 
         [0093]      FIG. 17  is an additional illustration that shows how the migration blocker rods  33  pass between the chordae tandea  6  in the commissures  19  and  20 . 
         [0094]      FIG. 18  is an additional drawing illustrating how the migration blocker rod  33  leans against the mitral groove  14  in the posterior side and the left and right fibrous trigons on the anterior side. 
         [0095]      FIGS. 19A, 19B, 20, and 21  show an example of a trans atrial approach for trans catheter implantation in the mitral position. In  FIGS. 19A and 19B , the catheter is advanced through the left atrium  8  and then through the native mitral valve to the left ventricle. The stent  30  in  FIGS. 19A and 19B  is crimped into the catheter shaft  220 . The migration blocker rods are as well crimped in the shaft  220  and can be crimped distally toward the apex  16 , proximally toward the entering point to the left atrium, or on top of the main frame  30 .  FIG. 20  shows the deployment of the stent  30 . The migration blocker rods  33  pass through the chordae  6  under the native commissures and circle the native leaflets. The migration blocker rods  33  are configured, in certain embodiments, to bypass or encircle the native leaflets without clamping them to the main frame  30 . Then, a completion of the deployment results in clamping the native annulus and allowing the rods  33  to prevent migration and rocking.  FIG. 21  shows that the catheter  220  is withdrawn backwards after completion of the deployment. 
         [0096]      FIGS. 22A, 22B, 23, and 24  show an example of a trans apical approach for trans catheter implantation in the mitral position. In  FIGS. 22A and 22B , the catheter shaft  220  is advanced through the apex  16  of the heart and then through the native mitral valve to the left atrium. The stent  30  in  FIGS. 22A and 22B  is crimped into the catheter shaft  220 . The migration blocker rods are as well crimped in the shaft and can be crimped distally toward the atrium, proximally toward the entering point to the apex  16 , or on top of the main frame  30 .  FIG. 23  shows the deployment of the stent  30 . The migration blocker rods  33  pass through the chordae  6  under the native commissures and circle the native leaflets. Then, a completion of the deployment results in clamping the native annulus and allowing the rods  33  to prevent migration and rocking.  FIG. 24  shows that the catheter is withdrawn backwards after completion of the deployment. 
         [0097]    It will be understood by those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.