Abstract:
A heart valve assembly has a frame comprising an inflow section, an outflow section, and a connecting section that is located between the inflow section and the outflow section. The inflow section has a plurality of legs that extend radially outwardly, and the connecting section has a greater flexibility than the inner section. The assembly also includes a plurality of leaflets coupled to the connecting section, a valve skirt extending from the leaflets towards the inflow section of the frame, and a cuff section, with the legs and the cuff section together defining a cuff for engagement with a native annulus.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to an aortic replacement valve, as well as methods and systems for transcatheter placement of the aortic replacement valve. 
         [0003]    2. Description of the Prior Art 
         [0004]    There are many aortic replacement valves that are available for trans-catheter replacement of a defective aortic valve. The current aortic valve designs are made of a metal frame with tissue valves, and skirt sutured on to the frame. The frame is mostly a skeleton-type design, allowing it to be crimped to a small profile for insertion and expansion in situ. 
         [0005]    Unfortunately, the current aortic valve designs still suffer from some important drawbacks. 
         [0006]    First, coronary access remains an issue. With the wire braided or slotted tube designs utilized by the current aortic valve frames, the cells are condensely-packed to achieve the required expansion force. The condensed cells could be too small to allow for catheters to pass through, and thereby make the later coronary access by catheters (for angioplasty and stenting) more difficult. 
         [0007]    Second, there is often a need to resheath the partially deployed valve assembly. The current aortic valves are either not retrievable upon partial deployment at regular body temperature due to its expansion force, or are retrievable only by reducing the frame&#39;s expansion force. In the latter situation, the reduced expansion force limits the suitability of the valve assembly to replacement of severely calcified native valves. 
         [0008]    Third, perivalvular leak (PVL) is still a problem with many of the existing transcatheter aortic valve assemblies. Many of the first generation valve assemblies did not address the PVL issue. The later generations started to add features, such as cuffs, to the inflow section. The cuff is essentially a separate component attached to the frame on the outside. However, adding such cuffs increases the profile of the valve assembly when crimped, thereby requiring a larger delivery system. 
         [0009]    Thus, there remains a need for a transcatheter aortic valve assembly that overcomes the shortcomings described above. 
       SUMMARY OF THE DISCLOSURE 
       [0010]    The present invention provides a way to make the valve assembly retrievable upon its deployment by up to two thirds of its length. Also, upon the expansion of its inflow end in the annulus, the valve assembly will form a soft cuff surrounding the inflow end to seal the gaps between the valve assembly and the annulus. 
         [0011]    The present invention accomplishes these objectives by providing a heart valve assembly having a frame comprising an inflow section, an outflow section, and a connecting section that is located between the inflow section and the outflow section. The inflow section has a plurality of legs that extend radially outwardly, and the connecting section has a greater flexibility than the inner section. The assembly also includes a plurality of leaflets coupled to the connecting section, a valve skirt extending from the leaflets towards the inflow section of the frame, and a cuff section, with the legs and the cuff section together defining a cuff for engagement with a native annulus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1A  is a perspective side view of an aortic valve assembly according to one embodiment of the present invention shown in an expanded configuration. 
           [0013]      FIG. 1B  is an enlarged side view of the inflow end of the assembly of  FIG. 1A . 
           [0014]      FIG. 2  is a top view of the assembly of  FIG. 1A . 
           [0015]      FIG. 3  is a perspective side view of the frame of the assembly of  FIG. 1A . 
           [0016]      FIG. 4  is a top view of the frame of  FIG. 3 . 
           [0017]      FIG. 5  is a bottom view of the frame of  FIG. 3 . 
           [0018]      FIG. 6  is a perspective view of the leaflet assembly of the valve assembly of  FIG. 1A . 
           [0019]      FIG. 7  is a side view of the leaflet assembly of  FIG. 6 . 
           [0020]      FIG. 8  is a top view of the leaflet assembly of  FIG. 6 . 
           [0021]      FIG. 9  is a side view of the frame of  FIG. 3  shown in its compressed configuration. 
           [0022]      FIG. 10A  illustrates a delivery system that can be used to deploy the valve assembly of  FIG. 1A , shown with the valve assembly inside the capsule of the delivery catheter. 
           [0023]      FIG. 10B  illustrates the valve assembly being partially released from the capsule of  FIG. 10A . 
           [0024]      FIG. 10C  illustrates the valve assembly being fully released from the capsule of  FIG. 10A . 
           [0025]      FIG. 11A  illustrates the delivery of the delivery catheter of  FIG. 10A  with the valve assembly in its capsule to the location of the aortic annulus. 
           [0026]      FIG. 11B  illustrates the valve assembly partially expanded at the location of the aortic annulus. 
           [0027]      FIG. 11C  illustrates the valve assembly fully deployed at the location of the aortic annulus. 
           [0028]      FIG. 12A  is a perspective side view of an aortic valve assembly according to another embodiment of the present invention shown in an expanded configuration. 
           [0029]      FIG. 12B  is an enlarged side view of the inflow end of the assembly of  FIG. 12A . 
           [0030]      FIG. 13  is a perspective side view of the frame of the assembly of  FIG. 12A . 
           [0031]      FIG. 14  is a side view of the leaflet assembly of the valve assembly of  FIG. 12A . 
           [0032]      FIG. 15  illustrates the valve assembly of  FIG. 12A  fully deployed at the location of the aortic annulus. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. 
         [0034]    The present invention provides an aortic replacement valve assembly  100  that is shown in fully assembled form in  FIGS. 1A, 1B and 2 . The assembly  100  has a frame  101  (see  FIGS. 3-5 ) that has an inflow section IS and an outflow section OS that is connected by a connecting section CS. The assembly  100  also has an integrated leaflet and skirt assembly  102  (see  FIGS. 6-8 ) that comprises a plurality of leaflets  106 , with the leaflet and skirt assembly secured to the inflow section IS and a portion of the connecting section CS. The assembly  100  can be effectively secured at the native aortic annulus. The overall construction of the assembly  100  is simple, and effective in promoting proper aortic valve function. 
         [0035]    As shown in  FIGS. 3-5 , the inflow section IS and the outflow section OS of the frame  101  can be made of one continuous wire, and can be made from a thin wall biocompatible metallic element (such as stainless steel, Co—Cr based alloy, Nitinol™, Ta, and Ti etc.). As an example, the wire can be made from a Nitinol™ wire that is well-known in the art, and have a diameter of 0.02″ to 0.04″. The inner and outer sections IS and OS define open cells within the frame  101 . Starting with the inflow section IS, the inflow section IS has a body portion that is made up by a plurality of annular rows of diamond-shaped cells  170  that are defined by a plurality of struts  152  connecting at apices  158  to encircle the cell  170 .  FIG. 3  shows three rows of staggered or alternating cells  170 , although two or four or more rows of cells  170  can be provided. A plurality of flared legs  171  extends from the outer-most apices  156  of the cells  170  to form an annular flange of legs  171 . Specifically, each leg  171  has a first part  172  which extends vertically from an apex  156  along the same plane as the struts  152  of the cell  170 , and then transitions to a first bend  155  to a second part  173  which extends radially outwardly (perpendicular to the first part  172 ), and then transitions to a second bend  153  to a third part  174  which extends vertically (perpendicular to the second part  173 ) which terminates at an ear  157 . 
         [0036]    The outflow section OS has a body portion that is made up one row of diamond-shaped cells  170  that are similar to the cells  170  in the inflow section IS. Connection beams  159  of the connector section CS connect the apices  160  of the cells  170  in the outflow section OS with the apices  154  of the inflow section IS. Another row of cells  180  is provided in the outflow section OS downstream from the row of cells  170  for the outflow section OS. The cells  180  are formed by struts  161  connecting at apices (e.g.,  151 ). The cells  180  can also be diamond-shaped but can be larger and shaped a little differently. The outflow end of the cells  180  terminate at apices  151 , and ears  162  are provided at selected apices  151 . 
         [0037]    The connecting section CS comprises the beams  159  that connect corresponding apices (e.g.,  154  and  160 ) of the cells  170  in the inflow section IS and the outflow section OS. Cells  190  are defined by the beams  159  and the struts of the cells  170  that are located at the boundaries of the inflow section IS and outflow section OS, and these cells  190  are generally shaped as a hexagon with two longer base sides defined by the beams  159  and four other shorter sides. These beams  159  can be made thicker (i.e., widened) by providing or cutting them to be thicker than the other struts. 
         [0038]    The cells  170 ,  180  and  190  have different shapes and sizes because it is preferred that the cells  190  and  180  have less expansion force than the cells  170 . The cells  170  on the inflow section IS are provided to be stiffer and less compressible than the cells  190  so as to ensure the expansion force needed for access to the annulus region when dealing with a calcified valve, while allowing the connecting section CS to be relatively easy to compress so that the connecting section CS can be retrieved during the deployment of the valve assembly. Also, the beam  159  is strong enough to withstand the deflection exerted from the commissure. Thus, the three sections IS, CS and OS are provided with the different cell size, cell shapes and beam width for the purpose of varying the flexibility and stiffness at the different sections IS, CS and OS. 
         [0039]    The valve assembly  100  is intended for use as an aortic replacement valve for the following valve sizes: 23 mm, 26 mm, 29 mm, 32 mm and 35 mm. As such, the height H 3  of the outflow section OS can be about 10-12 mm, the height H 2  of the connecting section CS and a portion of the inflow section IS (see  FIG. 1A ) can be about 10-12 mm, and the height H 1  of a portion of the inflow section IS can be about 10-12 mm. The three heights H 1 , H 2  and H 3  show the division of the frame  101  into three equally-divided lengths. As shown in  FIG. 9 , when the valve assembly  100  is in the compressed configuration, most of the valve assembly  100  along H 3  and H 2  can still be retrievable because of the compressibility of the connecting section CS, and this retrievable length is almost two-thirds of the overall length (H 1 +H 2 +H 3 ) of the valve assembly  100 . Also, as shown in  FIG. 9 , the legs  171  are straightened (instead of being bent into the parts  172 ,  173 ,  174  when in its deployed configuration) during delivery so that the row of legs  171  has a diameter that is the same as the diameter of the rest of the compressed frame  101 , thereby ensuring that the valve assembly  100  has a low profile when crimped. When the inflow section IS is released from the delivery capsule  2010  (see below), the shape-memory characteristic of the material will cause the legs  171  to be bent to form the various parts  172 ,  173  and  174 , thereby forming a row of legs  171  that has a diameter greater than the diameter of the remainder of the frame  101 . 
         [0040]    The leaflet and skirt assembly  102  is shown in  FIGS. 6-8 , and it includes three leaflets  106  sewn together at the commissures  111 . An inner tubular valve skirt  107  extends from the leaflets  106  to a flanged inflow skirt  109 . The leaflets  106  and the inner valve skirt  107  (including a concealed portion  113 ) are sewn to the inside of the struts  152  of the cells  170  in the inflow section IS. As shown in  FIG. 1A , the leaflets  106  are preferably positioned at the border between the connector section CS and the inflow section IS. The flanged inflow skirt  109  is formed by folding the skirt material over the ears  157  of the flanged legs  171 . The skirt material that is folded over the ears  157  is then extended at an angle along the outer surface of the struts  152  to form an angled outer skirt or cuff section  108 , which terminates at an annular stitch line  110 . As a result of the folding over of the skirt material, an empty space  112  is defined between the concealed portion  113 , the outer skirt  108 , and the inflow skirt  109 . As best shown in  FIGS. 2 and 11C , the valve assembly  100  is preferably deployed at the native aortic annulus in a manner such that the native aortic annulus impinges against the outer skirt  108 , with this portion of the outer skirt  108  (and the space  112  inside) acting both as a seal to prevent PVL, and as a buffer or cushion to protect the native annulus from impinging on the hard surface of the frame  101 . 
         [0041]    The skirt and leaflet material can be made from a treated animal tissue such as pericardium, or from biocompatible polymer material (such as PTFE, Dacron, etc.). The leaflets  106  and the skirts can also be provided with a drug or bioagent coating to improve performance, prevent thrombus formation, and promote endothelialization, and can also be treated (or be provided) with a surface layer/coating to prevent calcification. 
         [0042]    In addition, the length of the inflow section IS and the connecting section CS can vary depending on the number of leaflets  106  supported therein. For example, in the embodiment illustrated in  FIGS. 1A-8  where three leaflets  106  are provided, the length of the connector section CS can be 15-20 mm and the length of the inflow section IS can be 10-15 mm. If four leaflets  106  are provided, the respective lengths can be shorter, such that the length of the connector section CS can be 10-15 mm and the length of the inflow section IS can be 10-15 mm. These exemplary dimensions can be used for an assembly  100  that is adapted for use at the native aortic annulus for a generic adult. 
         [0043]    The assembly  100  of the present invention can be compacted into a low profile and loaded onto a delivery system, and then delivered to the target location by a minimally invasive medical procedure, such as by the use of a delivery catheter through transapical, or transfemoral, or transaortic procedures. The assembly  100  can be released from the delivery system once it reaches the target implant site, and can expand to its normal (expanded) profile either by inflation of a balloon (for a balloon expandable frame  101 ) or by elastic energy stored in the frame  101  (for a device where the frame  101  is made of a self-expandable material). 
         [0044]      FIGS. 10A-11C  illustrate how the assembly  100  can be deployed through the aorta of a patient using a transfemoral delivery. The delivery system includes a delivery catheter having an outer shaft  2020  that extends through a core body  2035  inside a handle  2050  at its proximal end, and has a capsule  2010  provided at its distal end. The valve assembly  100  is contained in its compressed configuration inside the capsule  2010 . The ears  162  of the outflow section OS are removably attached to ear hubs  2030  that are connected to an inner core  2025 . The inner core  2025  extends through the outer shaft  2020 , the capsule  2010  and the lumen defined by the valve assembly  100  to a distal tip  2015  that is at the distal-most part of the inner core  2025 . 
         [0045]    As shown in  FIGS. 10A and 11A , the valve assembly  100  is crimped and loaded inside the capsule  2010 , and the capsule  2010  is delivered to the location of the aortic annulus so that the valve assembly  100  is positioned at the location of the native aortic annulus. As shown in  FIGS. 10B and 11B , the capsule  2010  is slowly withdrawn to allow the inflow section IS to slowly expand at the location of the native aortic annulus. During this step, the distal tip  2015  and the capsule  2010  can still be pushed into the left ventricle or withdrawn from it to adjust the position of the valve assembly  100 . The greater expansion force imparted by the cuff section formed by the inflow section IS will help to secure or anchor the cuff formed by the annular row of legs  171  at the aortic annulus. If the positioning is not accurate, the valve assembly  100  can still be retrievable into the capsule  2010  simply by reversing the deployment and advancing the capsule  2010  to crimp it and reload the valve assembly  100  back into the capsule  2010 . Here, the varying flexibility allows the connecting section CS to be retrievable into the capsule  2010 , while the inflow section IS still has sufficient expansion force to anchor or secure the valve assembly  100  at the aortic annulus. 
         [0046]    As shown in  FIGS. 10C and 11C , further withdrawal of the capsule  2010  will release the remainder of the valve assembly  100 . The ears  162  become disengaged from the ear hubs  2030 , and the assembly  100  is completely expanded, and the entire delivery system can then be removed. As best shown in  FIGS. 1B and 11C , the valve assembly  100  is deployed at the native aortic annulus in a manner such that the native aortic annulus impinges against the outer skirt  108 , with this portion of the outer skirt  108  (and the space  112  inside) acting as a seal ring to prevent PVL. 
         [0047]    The assembly  100  of the present invention provides a number of benefits which address the shortcomings described hereinabove. 
         [0048]    First, the present invention provides improved access. The frame  101  has multiple zones, with the inflow section IS having the strongest expansion force to effectively expand the calcified leaflets and to secure the frame&#39;s position in the annulus. This is achieved by the condensed smaller cells  170  in the inflow section IS. In addition, the middle (connecting) section CS is to be deployed in the aortic sinus with no resistance to its expansion. It does not need the strong expansion but needs to support the force on the commissure generated by pressure on the prosthetic leaflets. Therefore, it is required to have minimum deflection in each valve closing cycle. This vertical rigidity is achieved in the present invention with a hexagon-shaped middle (connecting) section CS that has widened strut beams  159 . This design increases the open space for later catheter access to the coronary artery while keeping its rigidity for supporting the commissure. 
         [0049]    Second, the present invention allows for the valve assembly  100  to be easily resheathed. The present invention has an elongated hexagon-shaped connecting section CS which is relatively easier to collapse than the inflow section IS, which has smaller diamond-shaped cells, thereby making the valve assembly  100  retrievable even when deployed by up to two-thirds of its length. Meanwhile, the inflow section IS has a condensed cell design to ensure the expansion force needed for access even when dealing with a calcified valve. 
         [0050]    Third, the present invention minimizes PVL. The present invention extends the frame  100  into the cuff region, which is made of the extended metal frame and tissue material wrapped around the inflow edge of the frame. During the crimping and loading of the valve assembly  100  into the delivery catheter, the inflow section IS is extended and the skirt material around it is stretched so that the profile is the same as the other tissue-covered sections of the frame  101 , thereby resulting in no additional profile increase. Upon the release of the valve assembly  102  in situ, the extended frame section IS curls up to its preset shape and the tissue around it is folded back with it, thereby creating a soft cuff that functions to effectively seal against PVL. 
         [0051]      FIGS. 12A, 12B and 13-15  illustrate a second embodiment of the present invention. The valve assembly  100 A is essentially the same as the valve assembly  100  of the first embodiment except that the legs  174 A of the inflow section IS have a reversed configuration, and the leaflet and skirt assembly  102 A is configured to correspond to the configuration of the legs  174 A. The connecting section CS and the outflow section OS of the valve assembly  100 A can be the same for the embodiment shown in  FIGS. 1-11C , so the same numerals are used in both embodiments to represent the same or corresponding elements. 
         [0052]    As with the first embodiment, a plurality of flared legs  171 A extends from the outer-most apices  156  of the cells  170  to form an annular flange of legs  171 A. Specifically, each leg  171 A has a first part  173 A which extends radially outwardly (perpendicular to the plane of the inflow section IS), and then transitions to a second part  174 A which extends vertically (perpendicular to the first part  173 A) upwardly and which terminates at an ear  157 A. The second part  174 A is generally parallel to the plane of the inflow section IS. The elements  173 A,  174 A and  157 A correspond to similar elements  173 ,  174  and  157 , respectively. 
         [0053]    The leaflet and skirt assembly  102 A is shown in  FIG. 14 , and it includes three leaflets  106 A sewn together at the commissures  111 A. An inner tubular valve skirt  107 A extends from the leaflets  106 A to a flanged inflow skirt  109 A. The leaflets  106 A and the inner valve skirt  107 A are sewn to the inside of the struts  152  of the cells  170  in the inflow section IS. As shown in  FIG. 12A , the leaflets  106 A are preferably positioned at the border between the connector section CS and the inflow section IS. The flanged inflow skirt  109 A is formed by folding the skirt material over the parts  173 A and  174 A of the flanged legs  171 A, and then secured to the ears  157 A to form an outer skirt or cuff section  108 A, which terminates at an annular stitch line  110 A. As a result of the folding over of the skirt material, an empty space  112 A is defined between the outer skirt  108 A, and the inner valve skirt  107 A. As best shown in  FIG. 12B , the valve assembly  100 A is preferably deployed at the native aortic annulus in a manner such that the native aortic annulus impinges against the outer skirt  108 A, with this portion of the outer skirt  108 A (and the space  112 A inside) acting both as a seal to prevent PVL, and as a buffer or cushion to protect the native annulus from impinging on the hard surface of the frame  101 . 
         [0054]    The second embodiment bends the legs  171 A in an opposing way, with diamond cells underneath them. The cuff section defined by the outer skirt  108 A would be strong from the support of the main frame  107 A, and yet provide a soft cuff by the tissues sutured around the bent legs  171 A. The crimped profile is the same as main frame since the bent legs  171 A will be straightened out in the chilled saline and loaded into the delivery catheter. As with the first embodiment, the folding-over to form a cuff will occur at the body temperature upon deployment. With this second embodiment, the cuff section can be deployed directly in the annulus to expand and seal the calcified annulus. 
         [0055]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.