Abstract:
A mitral valve prosthesis and methods for implanting the prosthesis transapically (i.e., through the apex of the heart), transatrially (i.e., through the left atrium of the heart), and transseptally (i.e., through the septum of the heart). The prosthesis generally includes a self-expanding frame and two or more support arms. A valve prosthesis is sutured to the self-expanding frame. Each support arm corresponds to a native mitral valve leaflet. At least one support arm immobilizes the native leaflets, and holds the native leaflets close to the main frame.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit under 35 U.S.C. 119(e) to U.S. Provisional Patent Application 61/307,743, filed Feb. 24, 2010, which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is related to artificial heart valves. More specifically, the present invention is directed to an artificial mitral valve prosthesis and methods of implanting the prosthesis. 
         [0004]    2. Background Art 
         [0005]    The mitral valve exhibits two types of pathologies: regurgitation and stenosis. Regurgitation is the more common of the two defects. Typically, either defect is treated by a surgical repair. Under certain condition, however, the mitral valve must be replaced. Standard approaches to mitral valve replacement require cutting open the left side of the heart to access the native mitral valve. Such procedures are traumatic. Further, similar to aortic valve replacement, many patients requiring mitral valve replacement are inoperable or deemed to pose high surgical risk. This problem is lessened by the emerging techniques for minimally invasive mitral valve repair, but still many of those techniques require arresting the heart and funneling the blood through a heart-lung machine. What is needed is a mitral valve prosthesis and method of implantation that minimizes the traumatic impact on the heart while effectively replacing native leaflet function. A consistent, reproducible, and safe method to introduce a prosthesis into the mitral position in a minimally invasive fashion could be attractive for numerous reasons, such as: a) it can treat both functional and degenerative mitral regurgitation (MR); b) it can treat mitral stenosis; c) it can offer a remedy to inoperable patients, high risk surgical patients, and those that cannot tolerate bypass; d) it can allow less proficient surgeons to perform mitral valve procedures; and e) it can enable more consistency in measuring outcome. 
         [0006]    The following are herein incorporated by reference in their entirety: U.S. Pat. Nos. 5,354,330; 5,344,442; 5,908,451; 5,957,949; 6,296,662; 6,312,465; 6,458,153; 6,558,418; 6,730,118; 7,018,406; 7,018,408; and 7,137,184; U.S. Patent Application Publication Nos. 2003/0023300; 2003/0130729; 2004/0186563; 2004/0236411; 2004/0260389; 2005/0075720; 2005/0137688; 2005/0137690; 2005/0137691; 2005/0137695; 2005/0143809; 2005/0182483; 2005/0197695; 2005/0240200; 2006/0025857; 2006/0025855; 2006/0047338; 2006/0052867; 2006/0074485; 2006/0259136; 2006/0058872; 2006/0149360; and 2008/0071368; and PCT Publication Nos. WO 05/002466; and WO 06/070372; 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    Provided herein is a mitral valve prosthesis and methods for implanting the prosthesis transapically (i.e., through the apex of the heart), transatrially (i.e., through the left atrium of the heart), and transseptally (i.e., through the septum of the heart). The prosthesis generally includes a self-expanding frame and two or more support arms. A valve prosthesis is sutured to the self-expanding frame. Each support arm corresponds to a native mitral valve leaflet. One or more support arms act to immobilize the native leaflets, and hold the native leaflets close to the frame. Such configuration achieves numerous goals. For example, such configuration can: prevent the native leaflets from obstructing flow through the left ventricular outflow tract (LVOT); prevent the native leaflets from interacting with the prosthetic leaflets; recruit the native leaflets in minimizing peri-valvular leaks; maintain proper alignment of the valve prosthesis; avoid systolic anterior mobility; and maintain valve stability by preventing migration of the valve into the atrium or ventricle. The design of the prosthesis also mimics the native valve and supports a non-round in vivo configuration, which better reflects native valve function. 
         [0008]    The prosthesis is generally designed to include two or more commissural posts that are relatively parallel with and level to the ends of the prosthetic valve leaflets, which prevents interaction between the prosthesis and the LVOT and/or native aortic valve. The prosthesis is also generally designed such that diverging commissures are not required because the orifice area is sufficiently large and pressure recovery is not a concern. The inlet end of the prosthesis is wider than the valve segment at the native annular level to prevent migration into the ventricle and to improve sealing of the valve against the atrial wall. The inlet end of the prosthesis may also be designed asymmetrically to accommodate the anterior horn of the atrium, which is associated anatomically with the position of the aortic valve. Fixation barbs at the level of the inlet may provide further fixation to prevent device migration into the ventricle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
         [0009]    The accompanying figures, which are incorporated herein, form part of the specification and illustrate embodiments of a mitral valve prosthesis and methods of implantation. Together with the description, the figures further serve to explain the principles of and to enable a person skilled in the relevant art(s) to make, use, and implant the valve prosthesis described herein. In the drawings, like reference numbers indicate identical or functionally similar elements. 
           [0010]      FIG. 1A  is a perspective view of a mitral valve prosthesis, in accordance with one embodiment presented herein. 
           [0011]      FIG. 1B  is a perspective view of a mitral valve prosthesis, in accordance with an alternative embodiment. 
           [0012]      FIG. 2  is a side view of a mitral valve prosthesis, in accordance with an alternative embodiment presented herein. 
           [0013]      FIG. 3  is another side view of the mitral valve prosthesis of  FIG. 2 . 
           [0014]      FIG. 4  is a perspective view of the mitral valve prosthesis of  FIG. 2 . 
           [0015]      FIG. 5  is another perspective view of the mitral valve prosthesis of  FIG. 2 . 
           [0016]      FIG. 6  is a perspective view of a mitral valve prosthesis, in accordance with an alternative embodiment presented herein. 
           [0017]      FIGS. 7A-7F  depict a method of implanting a mitral valve prosthesis transapically. 
           [0018]      FIGS. 8A-8F  depict a method of implanting a mitral valve prosthesis transatrially. 
           [0019]      FIG. 9  is a view of an implanted mitral valve prosthesis, in accordance with one embodiment presented herein. 
           [0020]      FIGS. 10A-10D  show alternative embodiments of engagement arms for a mitral valve prosthesis. 
           [0021]      FIG. 11A  is a saggital cut through a human heart depicting the implanted mitral valve prosthesis of  FIG. 6 . 
           [0022]      FIG. 11B  is a saggital cut through a human heart depicting an implanted alternative embodiment to the mitral valve prosthesis of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The following detailed description of mitral valve prostheses and methods for implantation refers to the accompanying figures that illustrate exemplary embodiments. Other embodiments are possible. Modifications can be made to the embodiments described herein without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not meant to be limiting. 
         [0024]      FIG. 1A  is a perspective view of a mitral valve prosthesis  100 A, in accordance with one embodiment presented herein. Mitral valve prosthesis  100 A includes an inner support structure (or main frame)  102  and an outer support structure  104 . Outer support structure  104  includes outer engagement arms (or outer support arms)  106 . As shown, mitral valve prosthesis  100 A includes two outer engagement arms  106  to anatomically match the native mitral valve leaflets. Upon implantation outer engagement arms  106  clamp and immobilize the native mitral valve leaflets, and hold the native leaflets close to inner support structure  102 . Each outer engagement arm  106  includes a trough  110  and takes an upward concave structure having ends meeting at junctures, or commissure post  108 . 
         [0025]    Inner support structure  102  includes a distal section  112 , a relatively narrow throat section  114 , and a proximal section  116 . As used herein the term “distal” is understood to mean downstream in the direction of blood flow. The term “proximal” is intended to mean upstream in the direction of blood flow. Inner support structure  102  includes a generally uniform, circular cross-section along the length of the longitudinal axis of valve prosthesis  100 A. As shown, distal section  112 , narrow throat section  114 , and proximal section  116  include diamond-shaped cells  103 . Alternative shapes and configurations of the cells (or struts)  103  may be employed. Distal section  112  can be formed in a straight fashion (i.e., cylindrical and parallel to the longitudinal axis of prosthesis  100 A) or in a flared fashion (i.e., diverging away from the longitudinal axis of prosthesis  100 A). Proximal section  116  is generally formed to bulge outward from narrow throat section  114 , and may be formed straight or flared outward. Proximal section  116  is the blood inlet end of valve prosthesis  100 A. Proximal section  116  is generally wider than narrow throat section  114 , and is generally wider than the native valve segment at the native annular level. Such a configuration prevents migration of prosthesis  100 A into the ventricle and improves sealing of prosthesis  100 A against the atrial wall. 
         [0026]    Inner support structure  102  is also configured to be expandable (preferably self-expandable), and may be formed of a memory alloy such as NITINOL. Other biocompatible metals may also be used. Outer support structure  104  may also be formed of a memory alloy such as NITINOL, or other biocompatible metals. Inner support structure  102  and outer support structure  104  may be integrally formed, or may comprise separate modular components that are attached to one another. In one embodiment, inner support structure  102  is designed to flex and deform so as to mimic the natural cardiac movements of the heart through the cardiac cycle. In another embodiment, inner support structure  102  is designed in a rigid fashion to avoid flexing or deformation during the cardiac cycle. 
         [0027]    Sutured to inner support structure  102  is a prosthetic valve  118 . In one embodiment, valve  118  is sewn onto inner support structure  102  as described in U.S. Patent Application Publication No. 2008/0071368, which is incorporated herein, in its entirety, by reference. Valve  118  may be formed of a biocompatible synthetic material, synthetic polymer, an autograft tissue, xenograft tissue, or other alternative materials. 
         [0028]    Alternative designs may include three engagement arms, three leaflets, and/or three commissure posts. 
         [0029]      FIG. 1B  is a perspective view of a mitral valve prosthesis  100 B, in accordance with an alternative embodiment. Mitral valve prosthesis  100 B differs from prosthesis  100 A only in that proximal section  116  includes fixation barbs  190  to provide further fixation support and to prevent migration of prosthesis  100 B into the ventricle. 
         [0030]      FIG. 2  is a side view of a mitral valve prosthesis  200 , in accordance with an alternative embodiment presented herein.  FIG. 3  is another side view of valve prosthesis  200 .  FIG. 4  is a perspective view of valve prosthesis  200 .  FIG. 5  is another perspective view of valve prosthesis  200 . Similar to mitral valve prosthesis  100 A of  FIG. 1A , mitral valve prosthesis  200  includes an inner support structure  102  and an outer support structure  204 . However, outer support structure  204  differs from the outer support structure  104  of  FIG. 1A  in that outer support structure  204  includes outer engagement arms  106  that couple to the proximal end of commissure post  208 . 
         [0031]    As shown in  FIG. 3 , commissure post  208  extends upward from the ends of engagement arms  106 . In this embodiment, commissure posts  208  are parallel to and level with the ends of prosthetic valve leaflets  118 . In other words, the distal ends of commissure posts  208  are on plane with the ends of the valve leaflets  118 . When valve prosthesis  200  is implanted in the native mitral valve, the commissures of the native mitral valve sit within the vertex formed by the two ends of outer engagement arms  106 . As such, valve prosthesis  200  avoids interaction between valve  118  and the LVOT and/or native aortic valve. 
         [0032]      FIG. 6  is a perspective view of a mitral valve prosthesis  600 A, in accordance with another embodiment presented herein. Similar to mitral valve prosthesis  100 A of  FIG. 1A , mitral valve prosthesis  600 A includes an inner support structure  602  and outer support structure  104 . However, the shape of inner support structure  602  differs from the shape of inner support structure  102  of  FIG. 1A . Specifically, proximal section  616  of inner support structure  602  is formed asymmetrically to accommodate the anterior horn of the atrium, which is associated anatomically with the position of the aortic valve. Proximal section  616  is generally wider than narrow throat section  614 , and is generally wider than the native valve segment at the native annular level. Such a configuration prevents migration of prosthesis  600 A into the ventricle and improves sealing of prosthesis  600 A against the atrial wall. In one embodiment, narrow throat section  614  may have a circular cross-section, while proximal section  616  has a non-circular cross-section (e.g., oval, asymmetric, etc.). In an alternative embodiment, proximal section  616  may also include fixation barbs  690  (as shown with reference to prosthesis  600 B in  FIG. 11B ) to provide further fixation and to prevent migration of prosthesis  600 B into the ventricle. In general, the cross-section of inner support structure  602  is a non-uniform, non-circular shape. As shown, distal section  112 , narrow throat section  614 , and proximal section  616  include generally diamond-shaped cells. Alternative shapes and configurations of the cells (or struts) may be employed. 
         [0033]      FIGS. 7A-7F  depict a method of implanting a mitral valve prosthesis (e.g., prosthesis  100 A,  100 B,  200 ,  600 A, or  600 B) through a transapical procedure. As shown in  FIG. 7A , a trocar (or overtube)  730  is inserted into the left ventricle  728  through an incision created in the apex  724  of a patient&#39;s heart  720 . A dilator  732  is used to aid in the insertion of trocar  730 . In this transapical approach, the native mitral valve  722  is approached from the downstream relative to the blood flow. In  FIG. 7B , trocar  730  is retracted sufficiently to release the self-expanding engagement arms  106  of the mitral valve prosthesis. Dilator  732  is preferable presented between valve leaflets  722 . Trocar  730  can be rotated and adjusted as necessary to properly align the valve prosthesis. In  FIG. 7C , trocar  730  and the valve prosthesis is advanced forward such that outer engagement arms  106  clamp the native mitral valve leaflets  722 . As shown in  FIG. 7D , dilator  732  is advanced into the left atrium to further expose inner support structure  102  (or  602 ), and more specifically to begin disengaging proximal section  116  (or  616 ) from dilator  732 .  FIG. 7E  shows proximal section  116  (or  616 ) released from dilator  732 , and expanded to press against the interior wall for native mitral valve  722 . In  FIG. 7F , trocar  730  is withdrawn from heart  720  and the incision in apex  724  is closed. 
         [0034]      FIGS. 8A-8F  depict a method of implanting a mitral valve prosthesis (e.g., prosthesis  100 A,  100 B,  200 ,  600 A, or  600 B) through a transatrial procedure. As shown in  FIG. 8A , dilator  732  and trocar  730  are inserted through an incision  840  made in the wall of the left atrium of heart  720 . Dilator  732  and trocar  730  are advanced through the native mitral valve  722  and into the left ventricle of heart  720 . In  FIG. 8B , dilator  732  is withdrawn from trocar  732 . In  FIG. 8C , a guide wire  842  is advanced through trocar  730  to the point where the mitral valve prosthesis  100 A (or  100 B, or  200 , or  600 A, or  600 B) comes to the end of trocar  730 . As shown in  FIG. 8D , mitral valve prosthesis  100 A is advanced sufficiently to release the self-expanding engagement arms  106  from trocar  730 . Trocar  730  can be rotated and adjusted as necessary to properly align the valve prosthesis. In  FIG. 8E , trocar  730  is withdrawn slightly so as to clamp engagement aims  106  on the outside of native valve leaflets  722 .  FIG. 8F  shows trocar  730  completely withdrawn from heart  720  such that mitral valve prosthesis  100 A (or  100 B, or  200 , or  600 A, or  600 B) self-expands into position and assumes the function of native mitral valve  722 . 
         [0035]    In an alternative embodiment, a mitral valve prosthesis (e.g., prosthesis  100 A,  100 B,  200 ,  600 A, or  600 B) may be implanted transseptally. In such embodiment, the prosthesis is snaked through the femoral vein, into the right atrium. An incision is made in the septum of the heart to provide access to the left atrium. The prosthesis is then advanced through the incision in the septum and is implanted through a technique similar to the one outlined with regard to  FIGS. 8C-8F . Such a method would include: making an incision in a femoral vein; inserting a trocar through the incision in the femoral vein and advancing the trocar into the right atrium of the heart; making an incision in the septum of the heart; advancing the trocar through the incision in the septum of the heart and into the left atrium; advancing a mitral valve prosthesis through the trocar and into the left atrium of the heart; advancing the trocar past the native mitral valve and into the left ventricle of the heart; releasing the engagement arms from the trocar; retracting the trocar such that the engagement arms sit on the outer surface of the native mitral valve leaflets; releasing the inner support structure from the trocar; closing the incision in the septum; and withdrawing the trocar from the heart. 
         [0036]      FIG. 9  shows a perspective view of mitral valve prosthesis  100 A having engagement arms  106  clamping onto native mitral valve leaflets  722 . The commissure posts  108  of prosthesis  100 A sit on top of native valve leaflets  722  and are in line with the prosthetic valve leaflets  118 . As such the commissure posts  108  avoid interference with the LVOT and/or aortic valve. 
         [0037]      FIGS. 10A-10D  show alternative embodiments for engagement arms  106 ,  1006 ,  1106 , and  1206 . In  FIG. 10A , engagement arm  106  forms a U-shaped trough  110 . In  FIG. 10B , engagement arm  1006  forms a circular-shaped trough  1010 . In  FIG. 10C , engagement arm  1106  forms a bulging flask-shaped trough  1110 . In  FIG. 10D , engagement arm  1206  forms an undulating, bottle-nipple shaped trough  1210 . In alternative embodiments (not shown), the engagement arms may be shaped to include two or more parallel arches. 
         [0038]      FIG. 11A  is a saggital cut through a human heart  720  depicting the implanted mitral valve prosthesis  600 A of  FIG. 6 . The mitral cords  1123  connect native mitral valve  722  to the papillary muscles  1125 . Engagement arms  106  wrap around and lock into native mitral valve  722 . As shown in  FIG. 11A , proximal section  616  has a non-circular, asymmetric shape to accommodate the anterior horn of atrium  726 , which is associated anatomically with the position of aortic valve  1127 . The shape of proximal section  616  ensures axial fixation, prevents outflow obstruction, and seals prosthesis  600 A against the wall of left atrium  726 . 
         [0039]      FIG. 11B  is a saggital cut through a human heart  720  depicting an implanted mitral valve prosthesis  600 B. The mitral cords  1123  connect native mitral valve  722  to the papillary muscles  1125 . Engagement aims  106  wrap around and lock into native mitral valve  722 . As shown in  FIG. 11B , proximal section  616  has a non-circular, asymmetric shape to accommodate the anterior horn of atrium  726 , which is associated anatomically with the position of aortic valve  1127 . The shape of proximal section  616  ensures axial fixation, prevents outflow obstruction, and seals prosthesis  600 B against the wall of left atrium  726 . Further, barbs  690  penetrate to the mitral annulus and serve as a locking mechanism, together with engagement arms  106 , to prevent migration of prosthesis  600 B into left ventricle  728 . 
         [0040]    The foregoing description has been presented for purposes of illustration and enablement, and is not intended to be exhaustive or to limit the invention to the precise form disclosed. Other modifications and variations may be possible in light of the above teachings. The embodiments and examples were chosen and described in order to best explain the principles of the invention and its practical application and to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention.