Abstract:
A prosthetic heart valve includes an annularly collapsible and re-expandable supporting structure extending between an inflow end and an outflow end and including a plurality of struts, the inflow end having an inflow edge, a plurality of leaflets disposed inside the supporting structure and operative to allow flow in an antegrade direction from the inflow end to the outflow end but to substantially block flow in a retrograde direction from the outflow end to the inflow end, a first material disposed on a luminal surface of the supporting structure adjacent the inflow end, and a second material disposed on an abluminal surface of the supporting structure adjacent the inflow end, the first material and the second material being secured to selected struts of the supporting structure, and separately secured to each other adjacent the inflow edge.

Description:
[0001]    The present application is a continuation of U.S. patent application Ser. No. 13/848,466, filed Mar. 21, 2013, which is a continuation of Ser. No. 12/733,759, filed Mar. 18, 2010, now U.S. Pat. No. 8,425,593, which is a national phase entry under 35 U.S.C. §371 of International Application No. PCT/US2008/011153 filed Sep. 26, 2008, published in English, which claims the benefit of U.S. Provisional Application No. 60/995,648 filed Sep. 26, 2007, all of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Current collapsible prosthetic heart valve designs are for use within patients who may need a valve replacement (e.g., an aortic valve replacement), but who are not treated adequately by other means. A collapsible prosthetic heart valve is designed to be delivered into the patient in a collapsed condition via tube-like delivery apparatus. In the collapsed condition the valve has a reduced annular, radial, or circumferential size. Delivery of the valve into the patient can be less invasive than traditional open-chest/open-heart surgery. When the valve reaches the intended implant site in the patient, the valve re-expands or is expanded (e.g., balloon expanded) to operating size. The collapsing and re-expansion of the valve are preferably elastic, but may alternatively be plastic, the result of shape-memory properties of certain components of the valve, or various combinations of elastic, plastic, and/or shape-memory. Again, plastic expansion may be as a result of inflation of a balloon that is temporarily disposed inside the valve. Known designs of this general kind can be implanted percutaneously, trans-apically, or surgically, with or without resected and/or debrided native heart valve leaflets. 
       SUMMARY OF THE INVENTION 
       [0003]    The prosthetic heart valves disclosed herein incorporate a collapsible valve (which may or may not include independently flexing commissure posts) and unique ways in which to assemble the leaflets and ancillary components. 
         [0004]    In accordance with certain possible aspects of the invention, a prosthetic heart valve may include an annular, annularly collapsible and re-expandable supporting structure, and a sheet-like, flexible, leaflet member mounted inside the supporting structure so that a free edge portion of the leaflet forms a flexible chord across an interior of the supporting structure. Material of the leaflet may extend beyond an end of the chord and form a flap that is folded to lie, at least in part, in a cylindrical surface defined by one of the inner and outer surfaces of the supporting structure. 
         [0005]    The above-mentioned flap may be secured to the supporting structure. For example, the flap may be sutured to the supporting structure to secure the flap to the supporting structure. As a more particular example, the flap may lie, at least in part, in the cylindrical surface defined by the inner surface of the supporting structure. Alternatively, the flap may pass through the supporting structure to lie, at least in part, in the cylindrical surface defined by the outer surface of the supporting structure. 
         [0006]    The leaflet may have a secured line portion which is spaced from the free edge portion across an intervening belly portion of the leaflet. The secured line portion may be secured to the supporting structure, and additional material of the leaflet beyond the secured line portion away from the belly portion may form a second flap that is folded to lie, at least in part, in a cylindrical surface defined by one of the inner and outer surfaces of the supporting structure. 
         [0007]    The above-mentioned second flap may be folded toward the free edge portion of the leaflet and secured to the supporting structure inside the supporting structure. Alternatively, the second flap may be folded away the free edge portion and secured to the supporting structure inside the supporting structure. Especially in the latter case, the second flap may continue beyond an axial end of the supporting structure and may be additionally folded over that axial end and back outside of the supporting structure for additional securement to the outside of the supporting structure. 
         [0008]    A prosthetic heart valve in accordance with the invention may additionally include sheet-like, flexible, buffer material between the supporting structure and the leaflet. Buffer material can alternatively be provided so that it only outlines (covers) certain members of the supporting structure, instead of forming a more extensive continuous sheet that covers not only members of the supporting structure but also otherwise open cells of that structure. For example, such outlining or less extensive buffer material can be a dip-coated or sprayed-on polymer. 
         [0009]    The supporting structure of a prosthetic heart valve in accordance with the invention may include a plurality of annularly spaced commissure posts, each of which may be cantilevered from other structure of the supporting structure. The above-mentioned flap that extends beyond an end of the above-mentioned free edge chord of the leaflet may be secured to an associated one of the commissure posts. For example, this securement may be by suture material that passes through the flap and apertures through the associated commissure post. The flap may be folded around the associated commissure post. The associated commissure post may be bifurcated into two spaced apart members. The flap may pass through the commissure post between those two members. 
         [0010]    In accordance with another possible aspect of the invention, the supporting structure may include a plurality of annular, annularly collapsible and re-expandable substructures that are spaced from one another along an axis about which the supporting structure is annular. The supporting structure may further include a plurality of linking members that are substantially parallel to the above-mentioned axis and that interconnect the substructures without the linking members deforming when the substructures annularly collapse and re-expand. 
         [0011]    In accordance with yet another possible aspect of the invention, a leaflet structure for a prosthetic heart valve may include a sheet of flexible leaflet material having a central opening with three sides, each of the sides being shaped to form the free edge of a respective one of three operating leaflet portions of the leaflet structure. The sheet may additionally have three secured line portions, each of which is radially outward from a respective, associated one of the free edges, and each of which is arcuate so that it is radially farther from a midpoint of the associated free edge than from endpoints of the associated free edge. 
         [0012]    The above-mentioned sheet may define three leaflet-linking areas, each of which extends from a junction of a respective pair of the free edges to a junction of the secured line portions that are radially outward from the free edges in that pair. 
         [0013]    For use of the above-mentioned sheet, a prosthetic heart valve in accordance with the invention may include an annular, annularly collapsible and re-expandable supporting structure. The above-mentioned sheet may then be disposed in the supporting structure with the secured line portions and the leaflet-linking areas secured to the supporting structure so that the free edges can come together in the interior of the supporting structure. The supporting structure may include three annularly spaced commissure posts, each of which may or may not be cantilevered from other structure of the supporting structure. Each of the leaflet-linking areas may be secured to a respective one of the commissure posts. At least one of the leaflet-linking areas may pass outside the supporting structure at the commissure post to which that leaflet-linking area is secured. At least one of the commissure posts may be bifurcated into two spaced apart members, and the leaflet-linking area that is secured to that commissure post may pass between the two members of that commissure post. 
         [0014]    The above-mentioned sheet may continue radially outwardly beyond at least a portion of at least one of the secured line portions to form a flap. In use of the sheet in a prosthetic heart valve that includes a supporting structure as mentioned above, such a flap may be secured to the supporting structure. For example, the flap may be secured inside the supporting structure. Alternatively, the flap may be secured outside the supporting structure. 
         [0015]    As another possibility, in use of the above-mentioned sheet in a prosthetic heart valve that includes a supporting structure (as also mentioned above), the valve may also include sheet-like, flexible, buffer material between the supporting structure and the leaflet material. 
         [0016]    In accordance with other possible aspects of the invention, a prosthetic heart valve may include an annular, annularly collapsible and re-expandable supporting structure, which in turn includes a plurality of members disposed in a zig-zag pattern that extends in a direction that is annular of the supporting structure. At least two of the members forming such a zig-zag pattern meet at an apex that points away from the supporting structure parallel to an axis about which the supporting structure is annular. The valve may further include a sheet of flexible material secured to the supporting structure, and a plurality of flexible leaflets disposed inside the supporting structure and at least partly secured to the sheet. The sheet may be at least partly secured to the supporting structure via a suture attachment at the apex. The apex may be shaped to prevent the suture attachment from moving away from the apex in a direction opposite to a direction in which the apex points. 
         [0017]    As a specific example, the above-mentioned apex may include an eyelet through which the suture attachment passes. As another example, the apex may include an enlarged head on the end of a reduced neck that extends in the direction that the apex points, and a suture attachment for the above-mentioned sheet may be wound around the neck. As still another example, the apex may comprise a notch that opens in the direction that the apex points, and the above-mentioned suture attachment may be wound around the inside of the apex and the inside of the notch. The above-mentioned notch may be narrowed near its entrance to form an open eyelet. Such an open eyelet may be too small for passage of a suture needle, but the entrance may be large enough for suture material to slip through. 
         [0018]    Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1A  is a simplified elevational view of an illustrative embodiment of a component that can be used in prosthetic heart valves in accordance with the invention. 
           [0020]      FIG. 1B  is an isometric or perspective view of what is shown in  FIG. 1A . 
           [0021]      FIG. 2A  is a simplified elevational view of an alternative embodiment of what is shown in  FIG. 1A .  FIG. 2A  shows only the foreground portion of the depicted component. 
           [0022]      FIG. 2B  is similar to  FIG. 2A , but from a different angle and with parts of the background structure shown in addition to the foreground structure. 
           [0023]      FIG. 3A  is similar to  FIG. 2A , but with illustrative additional components added. 
           [0024]      FIG. 3B  is similar to  FIG. 3A , but with illustrative, still further components added. 
           [0025]      FIG. 4A  is a flat development of an illustrative embodiment of what is actually a cylindrical component, which can be used in prosthetic heart valves in accordance with the invention. 
           [0026]      FIG. 4B  is an elevational view of the cylindrical component that is shown in flat-development form in  FIG. 4A . 
           [0027]      FIG. 5A  is similar to  FIG. 4A  for another illustrative embodiment. 
           [0028]      FIG. 5B  is an enlargement of a portion of  FIG. 5A . 
           [0029]      FIG. 6  is an elevational view of an illustrative embodiment of another component that can be used in prosthetic heart valves in accordance with the invention. 
           [0030]      FIG. 7  is similar to  FIG. 6  for another illustrative embodiment. 
           [0031]      FIG. 8  is similar to  FIG. 7  for still another illustrative embodiment. 
           [0032]      FIG. 9  is similar to  FIG. 8  for yet another illustrative embodiment. 
           [0033]      FIG. 10  is an elevational view of an illustrative embodiment of still another component that can be used in prosthetic heart valves in accordance with the invention. 
           [0034]      FIG. 11  is a simplified perspective view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0035]      FIG. 12A  is a simplified, partial, top view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0036]      FIG. 12B  is similar to  FIG. 12A  for another illustrative embodiment. 
           [0037]      FIG. 12C  is similar to  FIG. 12B  for still another illustrative embodiment. 
           [0038]      FIGS. 13 and 14  are each generally similar to  FIG. 11 . 
           [0039]      FIG. 15A  is a simplified, partial, elevational view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0040]      FIG. 15B  is another view of the same general kind as  FIG. 15A . 
           [0041]      FIG. 16  is a bottom view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0042]      FIG. 17  is similar to  FIG. 5B  for another illustrative embodiment. 
           [0043]      FIG. 18A  is a simplified isometric or perspective view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0044]      FIG. 18B  is a simplified, partial, elevational view of an illustrative embodiment of several components in accordance with the invention. 
           [0045]      FIG. 19  is similar to  FIG. 10  for another illustrative embodiment. 
           [0046]      FIG. 20A  is a simplified, partial, top view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0047]      FIG. 20B  is a simplified sectional view of part of what is shown in  FIG. 20A . 
           [0048]      FIG. 21  is similar to  FIG. 19  for another illustrative embodiment. 
           [0049]      FIG. 22  is similar to  FIG. 18A  for another illustrative embodiment. 
           [0050]      FIG. 23A  is similar to  FIG. 12C  for another illustrative embodiment. 
           [0051]      FIG. 23B  is similar to  FIG. 23A  for another illustrative embodiment. 
           [0052]      FIG. 24A  is similar to  FIG. 5A  for another illustrative embodiment. 
           [0053]      FIG. 24B  is similar to  FIG. 5B  for another illustrative embodiment. 
           [0054]      FIGS. 25A and 25B  are each similar to  FIG. 21  for other illustrative embodiments. 
           [0055]      FIGS. 26A and 26B  are each similar to  FIG. 23B  for other illustrative embodiments. 
           [0056]      FIG. 27  is similar to  FIG. 22  for another illustrative embodiment. 
           [0057]      FIG. 28  is similar to  FIG. 24B  for another illustrative embodiment. 
           [0058]      FIGS. 29A and 29B  are respectively similar to  FIGS. 24A and 24B  for another illustrative embodiment. 
           [0059]      FIG. 30  is similar to  FIG. 1A  for another illustrative embodiment. 
           [0060]      FIG. 31  is similar to  FIG. 29B  for another illustrative embodiment. 
           [0061]      FIG. 32  is similar to  FIG. 8  for another illustrative embodiment. 
           [0062]      FIGS. 33A and 33B  are each similar to  FIG. 25B  for other illustrative embodiments. 
           [0063]      FIG. 34  is similar to  FIG. 26B  for another illustrative embodiment. 
           [0064]      FIGS. 35A and 35B  are each similar to  FIG. 15B  for another illustrative embodiment. 
           [0065]      FIG. 36  is similar to  FIG. 21  for another illustrative embodiment. 
           [0066]      FIG. 37  is similar to  FIG. 34  for another illustrative embodiment. 
           [0067]      FIGS. 38A and 38B  are respectively similar to  FIGS. 29A and 29B  for another illustrative embodiment. 
           [0068]      FIG. 39  is similar to  FIG. 30  for another illustrative embodiment. 
           [0069]      FIG. 40  is similar to  FIG. 32  for another illustrative embodiment. 
           [0070]      FIGS. 41A and 41B  are each similar to  FIG. 33B  for other illustrative embodiments. 
           [0071]      FIG. 42  is similar to  FIG. 37  for another illustrative embodiment. 
           [0072]      FIG. 43  is similar to  FIG. 35B  for another illustrative embodiment. 
           [0073]      FIG. 44  is similar to  FIG. 41B  for another illustrative embodiment. 
           [0074]      FIG. 45  is similar to  FIG. 42  for another illustrative embodiment. 
           [0075]      FIG. 46  is similar to  FIG. 43  for another illustrative embodiment. 
           [0076]      FIG. 47  is similar to  FIG. 36  for another illustrative embodiment. 
           [0077]      FIG. 48  is similar to  FIG. 5  for another illustrative embodiment. 
           [0078]      FIG. 49  is similar to  FIG. 46  for another illustrative embodiment. 
           [0079]      FIG. 50  is similar to  FIG. 38A  for another illustrative embodiment. 
           [0080]      FIG. 51  is similar to  FIG. 39  for another illustrative embodiment. 
           [0081]      FIG. 52  is similar to  FIG. 44  for another illustrative embodiment. 
           [0082]      FIGS. 53A and 53B  are each similar to  FIG. 7  for other illustrative embodiments. 
           [0083]      FIG. 54  is similar to  FIG. 35A  for another illustrative embodiment. 
           [0084]      FIG. 55  is similar to  FIG. 13  for another illustrative embodiment. 
           [0085]      FIG. 56  is similar to  FIG. 16  for another illustrative embodiment. 
           [0086]      FIG. 57  is similar to  FIG. 56  for another illustrative embodiment. 
           [0087]      FIG. 58  is similar to  FIG. 57  for another illustrative embodiment. 
           [0088]      FIG. 59  is similar to  FIG. 55  for another illustrative embodiment. 
           [0089]      FIG. 60  is similar to  FIG. 54  for another illustrative embodiment. 
           [0090]      FIG. 61  is similar to  FIG. 51  for another illustrative embodiment. 
           [0091]      FIG. 62  is similar to  FIG. 44  for another illustrative embodiment. 
           [0092]      FIG. 63  is similar to a portion of  FIG. 53B  for another illustrative embodiment. 
           [0093]      FIG. 64  is a simplified, partial, sectional view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0094]      FIG. 65  is a simplified, partial, elevational view of an illustrative embodiment of an assembly of several components in accordance with the invention. 
           [0095]      FIG. 66  is a simplified elevational view of an illustrative embodiment of a portion of a structure like that shown in  FIG. 65  in accordance with the invention. 
           [0096]      FIGS. 67, 68A, and 68B  are each similar to  FIG. 66  for other illustrative embodiments. 
           [0097]      FIGS. 69A and 69B  are each similar to  FIG. 48  for another illustrative embodiment. 
           [0098]      FIG. 70  is similar to  FIG. 50  for another illustrative embodiment. 
           [0099]      FIG. 71  is similar to  FIG. 61  for another illustrative embodiment. 
           [0100]      FIG. 72  is similar to  FIG. 47  for another illustrative embodiment. 
           [0101]      FIG. 73  is similar to  FIG. 65  for another illustrative embodiment. 
           [0102]      FIGS. 74A-C  are each similar to  FIG. 65  for other illustrative embodiments. 
           [0103]      FIG. 75  is similar to  FIG. 62  for another illustrative embodiment. 
           [0104]      FIG. 76A  is similar to  FIG. 63  for another illustrative embodiment. 
           [0105]      FIG. 76B  is similar to  FIG. 76A  with another illustrative component shown. 
           [0106]      FIGS. 77A-G  are simplified sectional views showing various illustrative embodiments of leaflet attachment to other components of valves in accordance with the invention. 
           [0107]      FIGS. 78A and 78B  are each similar to FIGS. like  FIGS. 53A-B  for other illustrative embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0108]    As just one example of a context in which the present invention may be employed, thousands of high-risk patients with severe aortic stenosis go untreated each year because they are deemed inoperable for a heart valve replacement. In an attempt to treat these patients, collapsible prosthetic heart valves have been developed to be inserted within the stenotic leaflets of these patients via percutaneous and/or trans-apical means. However, known designs may not sufficiently address several aspects of an optimal valve design, such as: (1) long-term durability, (2) mitral valve impingement, (3) perivalvular leakage, etc. Leaflet attachment can be a key element when considering some of these issues. The designs disclosed herein provide these high-risk patients with superior valves by better addressing these and other issues. 
         [0109]      FIGS. 1A-B  provide a general overview of an illustrative embodiment of a stent structure  10  that can be used in valves in accordance with this invention. These FIGS. show an expanded stent with independently flexing commissure posts  20   a - c  to reduce stress imparted to the valve leaflets (not shown). (Although this embodiment and several other embodiments have independently flexing commissure posts, still other embodiments are shown that also increase valve durability and that have only partially or not independently flexing commissure posts.) The independent posts are partly separate from the anchoring structure  30  downstream from the patient&#39;s valsalva sinus (upper portion of structure as viewed in  FIGS. 1A-B ) and  40  adjacent the patient&#39;s native aortic valve annulus (lower portion of structure as viewed in  FIGS. 1A-B ). In particular, upper free end portions of posts  20   a - c  are cantilevered from the annulus portion  40  of stent  10 . (Again, however, other embodiments may have only partially cantilevered or non-cantilevered commissure posts.) 
         [0110]      FIGS. 2A-B  show an illustrative embodiment of an expanded and contoured stent  10  with skirt flare  50  on base  40  and an extra-expanded section  30  for the aorta. (Reference numbers are reused for generally similar features in different FIGS. and different embodiments. Some FIGS. do not show the rear or the complete rear of all structures to avoid over-complicating the depictions.) Attachment of leaflets (not shown) to posts  20   a - c  and covering of the stent are important aspects of this invention. 
         [0111]      FIGS. 3A-B  show an illustrative embodiment of an expanded and contoured stent  10  with valve leaflets  60   a - c  and buffer layer  70  and outer cuff material  80 . Note that commissure posts  20  can lie perfectly vertically, or alternatively they can be angled inwardly to bias the leaflets inwardly and thereby help to keep them from hitting the prosthetic valve frame and/or the surrounding patient anatomy during opening. 
         [0112]    Attachment steps (in any order) after a stent  10  is at a predetermined diameter and polished are generally the following:
       Flexible leaflets  60   a - c  (e.g., polymer sheet or pericardial tissue sheet) are processed and cut to shape.
           For example, tissue leaflets  60   a - c  can be laid flat and fixed with the use of glutaraldehyde or triglycidylamine before being treated with an anti-calcification treatment such as at least a 60% solution of ethanol.   
           Buffer material or materials  70  (e.g., polymer sheet or pericardial tissue sheet) are processed and cut to shape.   Cuff material  80  (e.g., polyester fabric sheet) is formed into a tube of the appropriate diameter and cut to length.   Cuff material  80  can cover the lower portion of stent  10 , the entire portion of where the leaflets are attached, and/or the entire stent including an aorta section.   Intermediate materials of one or more layers (sheets) between stent  10  and leaflet material  60  may be applied for attachment, friction buffering, and tissue in-growth purposes. For example, an interface between two polymer or tissue layers may be beneficial, as compared to an unbuffered interface between leaflets  60  and stent  10 , for the above-mentioned reasons (e.g., less friction on and therefore wear of leaflets  60 ). Lubricious polymer coating of the stent instead of just sheets may also be incorporated.   Leaflets  60  are attached to stent  10  and around the circumference of the stent base.       
 
         [0120]    Specific details as to how the valve is assembled for different types of stent posts  20  are given below. 
         [0121]      FIG. 4A  shows the flat and collapsed state of a stent model used to laser-cut a part (stent)  10  from a tube (e.g., of a super-elastic metal such as nitinol or a balloon-expandable material such as cobalt chromium).  FIG. 4B  shows a round laser-cut part (stent)  10  in the collapsed state. This stent embodiment has independent flexing commissure posts  20   a - c  that are solid except for one set of eyelets  22 . Note, however, that these eyelets can be converted to any orifice shape such as an elongated slot. 
         [0122]      FIGS. 5A-B  show the flat and collapsed state of a stent model used to laser cut a part (stent)  10  from a tube and a close-up of the independent commissure posts  20   a - c . This stent  10  has independent flexing posts  20   a - c  that are solid with two sets of eyelets  22 . However, these eyelets could be converted to any orifice shape such as elongated slots. Note the bend line  52  of the skirt  50  and the base line  54  of the stent discussed in connection with later FIGS. 
         [0123]      FIG. 6  shows a buffering layer  70  that outlines the inner surface of a stent  10  (actually stent portion  40 ) and posts  20   a - c  to ensure that there is no contact between the leaflets  60  and any other material. Each rectangular section  72  is sutured to the inner diameter of a respective one of posts  20 . Top lip  74  covers the inner portion of the stent cells above bend line  52  (see also  FIG. 5B ). Bottom lip  76  covers the inner portion of the stent cells below bend line  52  to the bottom  54  of the stent (see also  FIG. 5B ). If section  78  is present, it can be wrapped around the bottom edge  54  of the stent from the inner diameter to the outer diameter to be terminated at the bottom stent edge or farther up. Note that the triangular cut-outs  79  in this section allow for flexible movement of the edge and actually will meet when wrapped around the bottom edge, while the rounded extreme bottom edge sections  77  will meet to form one continuous circular path around the stent. The triangular cut-outs  79  also allow for a minimized chance of tearing during expansion and contraction of the valve. 
         [0124]      FIG. 7  shows that the buffering layer  70  of this and all presented designs in this invention disclosure can be made from three single sections as shown in this FIG. (in contrast to one single piece as shown in  FIG. 6 ). 
         [0125]      FIG. 8  shows additional features that can be included in buffering designs in accordance with the invention. (See  FIG. 6  for general features that apply to all buffering designs of the invention.) Top flaps  71  wrap around the tops of the posts  20  from the inner diameter (ID) to the outer diameter (OD). Side flaps  73  wrap around the left and rights sides of each post  20  from the ID to the OD and are secured by sutures. 
         [0126]      FIG. 9  shows that in areas of high complexity, individual buffering strips  70  of various sizes and shapes can be wrapped about the stent frame and sutured in place.  FIG. 9  shows a generic rectangular strip  70  as an example. A rectangular strip can be rolled to form a cylinder of a desired height to cover any portion of the stent as well. 
         [0127]      FIG. 10  shows a single leaflet design  60  that is the foundation for many of the following leaflet designs in this disclosure. Material  61  above the top-most horizontal dotted line is for redundant coaptation where all three leaflets  60   a - c  meet under back-pressure. (The various dotted lines are shown primarily for reference, although they can also actually appear on the leaflet (either temporarily or permanently) as a visual guide or aid for use during assembly of a valve.) Side flaps  62  bend at the angled lines and provide an area to suture to the commissure post  20  ID. Note that since the leaflet may be cut from a flat sheet, there may not be a belly-shaped contour in the leaflet body  63 ; but when the angled side flaps  62  are attached to a vertical post  20 , this allows for the top portion of the leaflet to be closer to the central axis of the stent than the bottom portion, thus creating central coaptation. Side flaps  62  wrap around the left and right sides of the commissure posts  20  from the ID to the OD and are sutured down. Bottom flap  64  covers the ID portion of the stent cells below the bend line  52  to the bottom  54  of the stent. If this section is present, it can be wrapped around the bottom edge  54  of the stent from the inner diameter to the outer diameter to be terminated at the bottom stent edge or farther up, depending on its length. Note that the triangular cut-out  65  in this section allows for flexible movement of the edge and actually will meet when wrapped, while the rounded lower edge sections  66  will meet to form one continuous circular path around the stent. If desired, the material along curve  67  can be sutured down to form a natural belly shape for the leaflet. The bottom side flap  68  allows for some overlapping of adjacent leaflets to ensure that the inflow skirt edge is fully sealed. Triangular cut-outs  65  also allow for a minimized chance of tearing during expansion and contraction of the valve. 
         [0128]      FIG. 11  shows three single leaflets  60   a - c  being attached to stent  10 . The bottom flaps  64  and side flaps  62  can easily be seen before attachment occurs. 
         [0129]      FIGS. 12A-C  show three illustrative methods for leaflet and ancillary component assembly. Each of these FIGS. shows a top view of a commissure post  20  on the stent. (The commissure post is the large rectangle  20  in each of these FIGS.) In  FIGS. 12A and 12C  the commissure post has a single set of orifices  22 . In  FIG. 12B  the commissure post has two sets of orifices  22   a  and  22   b . In  FIGS. 12A and 12B  a buffering layer  70  is only on the ID surface of the post (which is the upper surface as viewed in these FIGS.). In  FIG. 12C  buffering layer  70  is wrapped all the way around the post. Lines  60   a  and  60   b  illustrate representative leaflets, and the arrows at the top ends indicate that the leaflet material continues beyond what is seen in the FIG. toward the central axis of the valve. The dotted lines  90  indicate a suture passing through the eyelet(s)  22  and through the leaflets  60 . Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  60  reduces abrasion, (2) leaflets  60  are sutured together to minimize any post gapping, (3) suture knots are on the OD of the post so as not to interfere with leaflet movement/abrasion, and (4) free ends  62  of the leaflets are curled back (e.g., toward the center of the valve) to provide an additional buffering layer. Note that in  FIG. 12C  the leaflets can only be wrapped around the post from the ID to the OD (as at  62 ) if there is enough room between stent cells when the valve is collapsed. 
         [0130]      FIG. 13  shows that on the fabric covering  80  on the ID of the stent there is a thin buffering material  70  to protect the leaflets  60  from abrading against the other valve surfaces. The lack of post gapping and the curled back leaflet edge before it is trimmed can be seen here at  100  (see also  FIG. 12A ). 
         [0131]      FIG. 14  shows how angled side flaps ( 62  of  FIG. 10 ) allow leaflets  60   a - c  to coapt along the central axis  110 . Note that under blood flow back-pressure, the leaflets will close tightly together with redundant coaptation. 
         [0132]      FIGS. 15A-B  show two different valve variations that have a few key differences.  FIG. 15A  has a cuff and buffer section  70 / 80  that covers all of the expanding cells of stent portion  40 . In  FIG. 15B  structure  70 / 80  goes half of the way up the stent cells  40  to approximately the bend line  52 , which may leave metal exposed for leaflet contact during opening.  FIG. 15A  has a buffering layer and leaflets that terminate at the lower edge  54  of the stent, whereas the buffering layer and leaflets of  FIG. 15B  completely wrap over the bottom edge  54  and are anchored near bend line  52 . Any or all of these features can be combined. 
         [0133]      FIG. 16  shows that there is a complete seal from the leaflets  60  and buffering layer all of the way from the stent ID around the edge of the stent base skirt to allow for a complete seal. 
         [0134]      FIG. 17  shows that to allow for more transfer of leaflet load to the stent posts  20  (as opposed to almost entirely through point loads from the sutures  90  on the stent ID), sutures and/or leaflet material may need to be passed over the top of the post  20  and secured to the OD as indicated at  120 . 
         [0135]      FIGS. 18A-B  show that to allow for more transfer of leaflet load (high-stress region  130  near leaflet free edge) to the stent post  20  (as opposed to almost entirely through point loads from the sutures  90 ), individual leaflets  60   a - c  can be secured to caps  140  placed over the post tops. Caps  140  can be made from fabric, polymer, and/or tissue components. 
         [0136]      FIG. 19  shows another single leaflet design in which many of the same features as described in  FIG. 10  can be utilized. The primary difference in this design is that the edge  62 / 64  is curled back onto the OD of the leaflet along the illustrated indicator lines  67 / 69 , instead of folded around the base of the stent. So instead of the leaflet edge sealing for inflow of the stent skirt, this design forms a pocket under back-pressure, with no seams along the suture line. For a 3D illustration see the next FIGS. As with the previous design, when these flaps are folded back, the triangular sections  65  close so the leaflet does not buckle. Since these flaps are folded back up against the leaflet OD, when the leaflet opens, the flaps  64  actually form a buffer between the upper base stent portion  40  and the leaflet. 
         [0137]      FIGS. 20A-B  shows 3D views of single leaflets  60 .  FIG. 20A  is a top view cross section, and  FIG. 20B  is a side view cross section. The arrows indicate where the leaflet flaps  62 / 64  are folded back onto the leaflet OD for one representative leaflet  60   b . Note that the curled-back design illustrated in  FIGS. 12A-B  is similar, except that in this design it runs along the entire edge  67 / 69  instead of just along the post. 
         [0138]      FIG. 21  shows a flat cutout of a continuous leaflet  160 . Instead of three single leaflets  60   a - c  mating together to form an orifice  150 , this design achieves this with one single continuous piece  160  of leaflet material. The indicated edge  170  is sewn to the stent ID in a similar manner as already described. Dashed line  180  indicates where leaflet material  160  is creased to form a commissure and attached to a post  20 . When the flat portion  190  of this design is pushed toward the central axis, it forms a belly as shown in the next FIG. 
         [0139]      FIG. 22  shows a folded 3D illustration of continuous leaflets material  160 . See the above discussion of  FIG. 21  for item descriptions. 
         [0140]      FIGS. 23A-B  show two methods for leaflet  160  and ancillary component assembly. These are views similar to  FIGS. 12A and 12C , with the same reference numbers used again for similar components. Major features to note are as follows: (1) a buffering layer  70  between the stent  20  and the leaflet material  160  reduces abrasion, (2) leaflets  60  (from continuous leaflet structure  160 ) are sutured together to minimize any post gapping, (3) suture knots are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, and (4) bottom edge of the leaflets are curled back up toward the center of the valve to allow for an additional buffering layer (analogous to the folding along line  67  in  FIGS. 20A and 20B ). Note that the main difference in attachment techniques is that either the leaflet material  160  wraps around the entire stent post ( FIG. 23A ) if there is enough room between cells when the valve is collapsed, or the leaflet material  160  is folded on the post ID only ( FIG. 23B ) in a continuous manner. 
         [0141]      FIGS. 24A-B  show the flat and collapsed state of a stent model used to laser cut a part (stent  10 ) from a tube and a close-up of the independent posts  20 . This stent has independent flexing posts  20  that are solid, with two sets of eyelets  22 , and an open section  24  at the top that forks (bifurcates) into two separate portions. See  FIGS. 1-5  for general features that are applicable to this and other designs. 
         [0142]    A buffering layer  70  that can outline the ID of this stent  10  can be seen in  FIGS. 6-8 , but would have a fork-shaped top. 
         [0143]      FIGS. 25A-B  show single leaflet designs (with many of the same features as conveyed in  FIGS. 10 and 19 ) that can be used for this stent design. The main difference is that the side flaps  62  have a slit  200  in them that allows the flap to wrap around the OD of the fork (on both sides of open section  24 ) at the top of the stent post  20 . 
         [0144]      FIGS. 26A-B  show two methods for leaflet  60  and ancillary component assembly. Once again, these are views that are similar to FIGS. like  12  and  23 , with the same reference numbers being used again for similar components. Major features to note are as follows: (1) a buffering layer  70  between stent  10  and leaflets  60  reduces abrasion, (2) leaflets  60  are sutured together (using sutures  90 ) to minimize any post gapping, (3) suture knots are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, (4) free ends  62  of leaflets  60  are curled back toward the center of the valve to provide an additional buffering layer in  FIG. 26A , (5) the gap  24  between forked posts  20  is just large enough for leaflet thicknesses to eliminate post gapping, and (6) the leaflets attached to the OD as in  FIG. 26B  allow for stresses caused from blood flow back-pressure to be transferred to the stent frame  10  instead of point loads at suture attachments. 
         [0145]      FIG. 27  shows a 3D view of individual leaflets  60  and the top portion  202  of the side flaps (above slit  200  in  FIG. 25A or 25B ) that wrap around the forked top section of the stent post  20 . 
         [0146]      FIG. 28  shows that another variation of this stent design is to eliminate the eyelets  22  on the lower portion of posts  20 . If there are no orifices to attach the leaflet flaps  62  to the posts, the leaflet flaps can be sutured together along the length of this lower section and/or through cuff material surrounding the expandable stent portion. 
         [0147]      FIGS. 29A-B  show the flat and collapsed state of a stent model used to laser cut a part (stent  10 ) from a tube and a close-up of the independent posts  20 . This stent has independent flexing posts  20  that are open in the middle  24  (i.e., bifurcated) with two sets of eyelets  22 . It also has a terminating single eyelet  26  for anchoring the leaflet base and other materials. See again  FIGS. 1-5  for general features that are applicable to this and other designs. 
         [0148]      FIG. 30  shows an example of a design variation with the non-expanding open stent post  20  and flared skirt  50 . 
         [0149]      FIG. 31  shows a close-up of the flat and collapsed state of a stent model used to laser cut a part (stent  10 ) from a tube with independent commissure posts  20 . This stent has independent flexing posts  20  that are open in the middle (i.e., at  24 ), with two sets of eyelets  22 . Additionally, this design has a connection  28  higher up on the stent posts  20 , thus making the posts less cantilevered and therefore possibly less flexible if needed. However, the valve assembly is not disrupted when internally mounting the leaflets through the center slot  24  of the stent posts. See again  FIGS. 1-5 and 29  for general features that are applicable to this and other designs. 
         [0150]      FIG. 32  shows a buffering layer design including features that can be in addition to those shown in  FIG. 6 . Rectangular flaps  72  outline the ID of stent posts  20 . An “I” shaped slit  210  is cut through material  70  and the resulting flaps are wrapped through the middle portion  24  of the stent post  20  from the ID to the OD, then secured in place. 
         [0151]      FIGS. 33A-B  show single leaflet designs, with many of the same features as conveyed in  FIGS. 10 and 19 , which can be applied to this stent design. The main difference is that the entire side flaps  62  pass through the middle slot ( 24  of  FIG. 29 ) and around to the OD, where it is secured (see next FIG.). 
         [0152]      FIG. 34  shows one method for leaflet and ancillary component assembly. Once again, this is a view similar to FIGS. like  12  and  23 , with the same reference numbers being used again for similar elements. Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  60  reduces abrasion, (2) the gap  24  between sides of the post  20  is just large enough for leaflet thicknesses to eliminate post gapping, (3) suture knots (associated with sutures  90 ) are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, and (4) the leaflets  60  attached to the OD of posts  20  allow for stresses caused by blood-flow back-pressure to be transferred to the stent frame instead of point loads at suture attachments. 
         [0153]      FIGS. 35A-B  show an example of this type of design with single leaflets  60  pulled through a center slot  24  and wrapped around to the OD of the stent post  20 . Also note that the buffering material  70  and leaflets  60  wrap slightly around the stent base as indicated at  220 . In some areas these FIGS. show the leaflet material as though transparent. 
         [0154]      FIG. 36  shows a flat cutout of a continuous leaflet  160 . Instead of three single leaflets  60  mating together to form an orifice  150 , this design achieves this with one single continuous piece  160 . The indicated edge  170  is sewn to the stent ID in a similar manner as already described. Dashed lines  180  indicate where one representative commissure of the leaflets is creased and pulled through the central slot  24  of the post  20 . When the flat portion  190  of this design is pushed toward the central axis, it forms a belly as shown in previous FIGS. 
         [0155]      FIG. 37  shows one method for leaflet and ancillary component assembly. Again,  FIG. 37  is a view similar to FIGS. like  12  and  23 , and the same reference numbers are used in all FIGS. of this type to indicate similar components. Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  160  reduces abrasion, (2) the gap  24  between sides of the post  20  is just large enough for leaflet thicknesses to eliminate post gapping, (3) suture knots (associated with sutures  90 ) are on the OD of the post  20  so as not to interfere with leaflet  160  movement/abrasion, (4) the leaflets  160  attached to the OD (at  180 ) allow for stresses caused from back-pressure to be transferred to the stent frame  10  instead of point loads at suture attachments, and (5) the leaflet  160  is fully sealed at the commissures  20 . 
         [0156]      FIGS. 38A-B  show the flat and collapsed state of a stent model used to laser cut a part (stent  10 ) from a tube and a close-up of the independent commissure posts  20 . This stent has independent flexing posts  20  that are open in the middle  24  with two sets of eyelets  22 . Additionally, this design has an opening  28  at the bottom of the slot  24 , which allows the post  20  to expand into a triangular shape. See again  FIGS. 1-5  for general features that are applicable to this and other designs. 
         [0157]      FIG. 39  shows an example of a stent variation with a central vertical slot  24  when in a collapsed state that was formed into a triangular opening  24 / 28  in an expanded state. The triangular opening of this post  20  more closely mimics the contoured shape of a native valve than, say, a vertical non-expanding post. 
         [0158]      FIG. 40  shows a buffering layer design including features that can be in addition to those shown in  FIG. 6 . The upwardly extending post flaps  72  outline the ID of stent posts  20  when those posts are expanded into a triangular shape (e.g., as shown at  24 / 28  in  FIG. 39 ). A slit  210  is cut through buffering material  70  and the resulting flaps are wrapped through the middle portion  24 / 28  of the stent posts  20  from the ID to the OD, then secured in place. 
         [0159]      FIGS. 41A-B  show single leaflet designs, with many of the same features as conveyed in  FIGS. 10 and 19 , which can be applied to this stent design. The main difference is that the side flaps  62  at the commissures are spread apart (due to the triangular stent post opening  24 / 28 ), thus additional sealing measures are needed. 
         [0160]      FIG. 42  shows one method for leaflet and ancillary component assembly. This is yet another FIG. similar to FIGS. like  12  and  23 , and which uses the same reference numbers for similar elements. In addition, line  230  indicates a patch having the same or similar material properties as elements  70  or  60  that seals the triangular opening  24 / 28  in the posts  20 . Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  60  reduces abrasion, (2) suture knots (associated with sutures  90 ) are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, (3) the leaflets  60  attached to the OD via flaps  62  allow for stresses caused from back-pressure to be transferred to the stent frame  10  instead of point loads at suture attachments  90 , and (4) the triangular-shaped posts  20 / 24 / 28  more closely mimic the contour shape of a native valve, thus functioning more optimally. 
         [0161]      FIG. 43  shows an example of a stent variation with an open expanding post  20  that results in a triangular commissure area  24 / 28  that more closely mimics the contour shape of a native valve. A patch  230  is sutured through the eyelets  22  and around the base of the stent  10  to ensure a sealed environment. Note also that there is a double layer of cuff material  80  on the stent OD to aid in better sealing and tissue in-growth when pushed against native aortic root tissue. 
         [0162]      FIG. 44  shows a single leaflet design, with many of the same features as conveyed in  FIG. 10 , which can be applied to this stent design. The main difference is that one side flap  62  has an extension  162  that is used to seal the triangular-shaped opening. 
         [0163]      FIG. 45  shows one method for leaflet and ancillary component assembly. This is again similar to  FIG. 42 , and the same reference numbers are used for similar elements in both of these FIGS. Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  60  reduces abrasion, (2) suture knots are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, (3) the gap  24  is large enough for leaflet thicknesses to eliminate post gapping, (4) the leaflets  60  attached to the OD of post  20  allow for stresses caused from blood flow back-pressure to be transferred to the stent frame  10  instead of point loads at suture attachments  90 , and (5) the doubling back of the one leaflet at  162  aids in sealing the triangular stent post opening  24 / 28 . 
         [0164]      FIG. 46  shows an example of a single leaflet design with an enlarged triangular side flap  162  that is doubled back over itself to aid in sealing the triangular expanded post opening  24 / 28 .  FIG. 46  omits depiction of the sutures that are typically used to secure the leaflet and flap material to the stent frame. 
         [0165]      FIG. 47  shows a flat cutout of a continuous leaflet  160  with several features that aid in the attachment and sealing for an expanding post  20 / 24 / 28  design. Flaps  240  with triangular cutouts  242  are wrapped around the base of the stent  10 . Edge  250  is sutured to the stent  10  to form the base of the leaflet belly. Edge  244  is secured around the base of the stent  10 . Sections  260  are pulled through the triangular post opening  24 / 28 , folded around the OD of the post  20 , and doubled back on themselves. Sections  262  cover up the triangular openings  24 / 28 . Flaps  270  extend toward the base of the stent to enhance sealing of covers  262  and are joined to the other flaps  240  along their edges  246  and  276 . See the next FIG. for more detail. 
         [0166]      FIG. 48  shows one method for leaflet and ancillary component assembly. This is again similar to  FIG. 45 , and again uses the same reference numbers for similar elements. Major features to note are as follows: (1) a buffering layer  70  between the stent  10  and the leaflets  160  reduces abrasion, (2) the gap  24  between sides of the posts  20  at the upper apex of the triangular stent post opening is just large enough for leaflet thicknesses to eliminate post gapping at that location, (3) suture knots are on the OD of the post  20  so as not to interfere with leaflet movement/abrasion, (4) the leaflets  160  attached to the OD of post  20  allow for stresses caused from blood flow back-pressure to be transferred to the stent frame  10  instead of point loads at suture attachments  90 , and (5) the leaflets  160  are fully sealed at the triangular commissures  20 / 24 / 28  as indicated at  262 . 
         [0167]      FIG. 49  shows an example of a single leaflet design doubled over itself at the edges  260  with a triangular section  262  in the middle to achieve a continuous tight seal. 
         [0168]      FIG. 50  shows further development of structures like those shown in  FIGS. 5A and 5B .  FIG. 50  shows a combination of eyelets  22  and slots  23  (already mentioned as a possibility earlier in this specification). The top and bottom post eyelets  22  anchor the leaflets  60  into position, and the slots  23  allow for easier assembly and multiple passes of a stitching needle.  FIG. 50  shows the metal structure  10  in a flat or planar depiction and in its collapsed condition or configuration. Again, there is a combination of eyelets  22  and slots  23  on the commissure posts  20  for leaflet  60  attachment. Eyelets  21  in other areas can be variously used to attach leaflets  60 , cuff material  80 , and/or buffering material  70 .  FIG. 51  shows the  FIG. 50  structure in its expanded state. 
         [0169]      FIG. 52  shows an illustrative simplification of a single leaflet design of the general type that is shown in  FIGS. 10 and 19 . This simplified version allows the technician to assemble and trim the valve as needed, since there can be a variability in how the tissue behaves. This design also reduces the amount of openings to enhance sealing. The same principles apply as are discussed above in connection with  FIGS. 10 and 19 . Note also that this design can be used for  FIGS. 10 and 19  valves, and then trimmed to the shape of the stent  10  if needed. 
         [0170]      FIGS. 53A and 53B  show further development of structures of the type that are shown in  FIGS. 12A-C . In particular,  FIGS. 53A and 53B  show the front (outer diameter) view of a straight solid commissure post  20  and suture attachment  90   a  and/or  90   b  for leaflets  60 . Note that these basic concepts can be used on the other post designs.  FIG. 53A  shows sutures  90   a  only looped around the stent material in the vertical direction.  FIG. 53B  shows sutures  90   a  in the vertical direction and sutures  90   b  in the horizontal direction, which is more indicative of what is shown in the top views of  FIGS. 12A-C . 
         [0171]      FIGS. 54-57  show further development of structures of the general type shown in  FIGS. 13-16 .  FIGS. 54-57  are examples of modified stents  10  with tissue structures added.  FIG. 54  is a side view of a valve with tissue leaflet  60  attachment like  FIG. 53A .  FIG. 55  is a top view similar to  FIG. 13 , but with tissue leaflets  60 .  FIG. 56  is a bottom view with leaflet tissue wrapped around the bottom edge. (This leaflet tissue may also be over other layers of fabric and/or buffer material, depending on the design of the valve.)  FIG. 57  is a bottom view with tissue terminated at the bottom edge. Note also that the traces  300  for the leaflet shape are shown. These traces  300  can be temporary (or permanent) markings on the leaflet material to help the assembly technician properly shape and assemble the valve. 
         [0172]      FIGS. 58-60  show further development of structures like those shown in  FIG. 20 .  FIGS. 58-60  show valves built with this concept to further clarify how the valve actually looks.  FIG. 58  is a bottom view of leaflets folded to form pockets when the free edges of the leaflets are coapting.  FIG. 59  is a top view showing continuous pockets  310 .  FIG. 60  is a side view showing continuous pockets  310  and the rolled up leaflets trimmed to the outline of the stent at  320 . Buffer and cuff material can also be shaped to outline the contour of the expandable stent portion. 
         [0173]      FIG. 61  shows further development of structures like those shown in  FIGS. 30 and 31 .  FIG. 61  shows a further developed version of a nitinol part (stent)  10  that has been expanded. This design also incorporates eyelets  22  and slots  23 , as well as eyelets  21  in various locations around the stent for attachment. Note that this design also has an extra row of closed-perimeter, open-centered, circumferentially collapsible/expandable cells on the bottom section  40 / 50  as compared to the earlier examples. 
         [0174]      FIG. 62  shows a single leaflet shape  60  which may have several advantages. For example, as compared to some leaflet shapes described earlier in this specification, the  FIG. 62  shape can reduce the amount of leaflet tissue that needs to be collapsed when the prosthetic valve is collapsed. This can help the prosthetic valve collapse to a smaller size for less invasive delivery into a patient. This leaflet shape can also help to redistribute high stress areas in the base of the valve belly where tear-out might otherwise tend to occur. All of these modifications can improve valve function and durability. 
         [0175]    As in some earlier-described embodiments, lines  300  are indicator lines on leaflet  60  to help with assembly of the leaflet into a prosthetic valve. In addition, some of these lines serve to demarcate certain portions of the leaflet in the following discussion. Line  300   a - b  is a line along which leaflet material outside the line can be folded in on leaflet material inside the line. Especially line  300   b  is also a line along which the base of the leaflet may be sutured to other structure of the valve. For example, this may result in securing the base of the leaflet through cuff material  80  of the valve. This arrangement helps to distribute stresses at the base of the leaflet (e.g., in the area indicated generally by reference number  400 ) upwardly along curve  300   b  (e.g., into the areas indicated generally by reference number  410 ) to spread out these stresses and prevent them from concentrating right at the leaflet base. For example,  FIG. 64  shows how leaflet material  62   b  outside indicator line  300   b  may be folded up outside the remainder of a leaflet  60 . This produces a doubled-over layer of leaflet material, which can be sutured through (including to other structure of the valve) using sutures  90  to improve durability. 
         [0176]    Returning to  FIG. 62 , and also now referring to a representative prosthetic valve commissure post  20  as shown in  FIG. 63  for use with the  FIG. 62  leaflet, leaflet flap portion  62   a  may be positioned relative to post  20  so that portion  62   a  sits above the top-most horizontal eyelet  23   a  in post  20 . Leaflet flap portion  62   c  is then positioned between horizontal eyelet  23   a  and the top-most vertical eyelet  23   d  in post  20 . Below flap section  62   c  is a further leaflet flap section  62   d , which is positioned for attachment (e.g., via sutures) to three vertical eyelets  23   d  in the upper portion of stent post  20 . Dotted line  420  in  FIG. 63  indicates the approximate boundary of leaflet flap portion  62   d  when thus secured to post  20 . The area of post  20  below eyelets  23   d  can be used as additional area for, e.g., cuff  80  attachment, hiding suture knots, and other features. 
         [0177]    As compared to some earlier-described leaflet embodiments, the  FIG. 62  leaflet can include less leaflet material outside indicator line  300   b . As noted earlier, this can help reduce the amount of leaflet material in the valve and thereby facilitate collapsing the valve to a smaller circumferential size. 
         [0178]    Turning now to another consideration that may be important in construction of prosthetic heart valves in accordance with the invention, when a leaflet  60  is secured through cuff material  80 , it may be desirable to ensure a durable securement of the leaflet with reduced movement that could lead to cuff/suture/leaflet abrasion. Termination of a cuff  80  (especially when the stent is flared outward as at  50  in some embodiments herein) can be difficult.  FIG. 65  and several subsequent FIGS. show structures that can help to address these issues. 
         [0179]    As shown in  FIG. 65 , cuff  80  is secured by outlining the struts of the cells that form stent portions  40  and  50  with whip stitch sutures  90   a . In addition, stent portions  40  and  50  are constructed so that they include several annularly extending serpentine, undulating, or zig-zag members  42   a - c  that are connected to one another by vertical bars  44 . Serpentine members  42   a - c  annularly compress or expand to allow the prosthetic valve to circumferentially collapse or expand. But vertical members  44  do not change length during such annular compression or expansion of the serpentine members. This helps to reduce the amount by which the prosthetic valve changes axial length during circumferential compression or expansion. This in turn can help reduce any tendency of cuff  80  to shift relative to stent portion  40 / 50 . Vertical bars  44  can also be secured to cuff  80  by suture stitches  90   b . In this example, cuff  80  and buffer material (hidden between the fabric of cuff  80  and leaflets  60 ) are mounted in the inside diameter (“ID”) of the stent and can extend any distance up or down the height of the stent frame. (Although  FIG. 65  shows all of components  20 ,  42 , and  44  one-piece with one another, some or all of these components may initially be separate from one another and then assembled with the other components.) 
         [0180]    In addition to the above, the invention can address possible difficulty in firmly securing cuff  80  to stent cell ends. For example, especially when stent portion  40  is flared as at  50 , the adjacent cuff material  80  may have a tendency to slip vertically along the stent when a leaflet  60  is secured to the cuff material and under load. Reference number  440  in  FIG. 65  points to a representative location where this may be an issue. Passing a suture through an eyelet  91  at such a location  440  can help prevent material slip.  FIGS. 66-68  also show several others shapes that can be provided at the top and/or bottom of stent cells to help secure the cuff  80  to the stent more securely. For example,  FIG. 66  shows providing an enlarged knob  450  on the end of a representative stent cell  40 / 50 . Knob  450  is connected to the stent cell by a small neck region  452 . Suture material  90  can be wound around neck  452  as shown in  FIG. 66  to help prevent any other material that is secured to the stent by suture  90  from moving upwardly (in this example) away from the depicted stent cell end. 
         [0181]    As another example,  FIG. 67  shows a notch  460  in the stent material, which notch opens away from the associated stent cell end  40 / 50 . Suture material  90  can pass (repeatedly) from the stent cell end through notch  460  and back into the stent cell end to ensure that the suture (and anything secured by the suture) cannot shift upwardly (in this example) relative to the stent cell end. 
         [0182]    As still another example,  FIG. 68A  shows a partially formed eyelet  470  at the end of a stent cell  40 / 50 . Eyelet  470  is large enough for suture material  90  to pass through, but it may not be large enough for the suture needle to pass through. However, suture material  90  can be pulled into eyelet  470  through the open side  472  of the eyelet (which open side faces away from the apex or end of stent cell  40 / 50 ). Suture material  90  may pass (repeatedly) from inside stent cell  40 / 50  through eyelet  470  and back into stent cell  40 / 50  in a loop,  FIG. 8 , or other pattern to secure suture  90  and any other material (such as cuff  80 ) that is engaged by suture  90  to the end of the stent cell. Again, as in the case of the structures shown in  FIGS. 66 and 67 , this is done in such a way that other material (such as cuff  80 ) that is secured by suture  90  cannot move upwardly (in this example) relative to the end of stent cell  40 / 50 . 
         [0183]      FIG. 68B  shows an alternative to  FIG. 67  in which the suturing  90  is interlocked with itself as part of passing through notch  460 . The interlocking shown in  FIG. 68B  can also be used with other stent frame shapes such as the shape shown in  FIG. 68A . 
         [0184]      FIG. 69A  shows a possible modification of a structure like that shown in  FIG. 12B . In this alternative a reinforced core  500   a  or  500   b  lines the creased area that the flaps of leaflets  60   a  and  60   b  are folded around. The core material  500   a/b  can be other tissue, polymer, metal, and/or fabric. The flap of the leaflet  60   a  or  60   b  is sutured ( 90   a  or  90   b ) through the stent  20  in a manner similar to what has already been shown. The flaps of the leaflets  60   a  and  60   b  can be additionally wrapped around the core(s)  500   a/b  and secured via additional suturing  510  to form a bundle. This may add more reinforcement from tissue tears and may also mitigate leaflet abrasion as illustrated by  FIG. 69B . By binding the leaflet (e.g.,  60   b ) and core (e.g.,  500   b ), the leaflet is not allowed to open all of the way up to hit the frame  10  of the stent. In other words, a clearance like that indicated by double-headed arrow  520  in  FIG. 69B  is maintained. 
         [0185]      FIG. 70  shows an example of a self-expanding stent design with the downstream-most connections  530  between commissure posts  20  and the remainder of annulus portion  40  more than 50% up the post height in the direction of blood flow through the implanted valve. This means that in this embodiment the posts  20  are less cantilevered than in some other embodiments. This design still retains the ability to attach the leaflets to other structure of the valve in ways similar to what has been described for other embodiments. 
         [0186]      FIG. 71  shows an example of a balloon-expandable stent design with the downstream-most connections  530  between each stent post  20  and the remainder of the stent  10 / 40  all the way up to the top of the posts  20 .  FIG. 71  shows stent  10  in its fully expanded state. This design still retains the ability to attach the leaflets of the prosthetic valve to other structure of the valve in ways that are similar to what is shown and described for other embodiments. The  FIG. 71  stent includes attachment structures  470 / 472  at the base of the stent that are similar to what is shown in  FIG. 68 . These can also be used as interlocks for attachment of the prosthetic valve to a delivery system for that valve. 
         [0187]      FIG. 72  shows another example of one continuous sheet  160  of leaflet material that can be shaped (when attached to a valve stent, etc.) to provide all three leaflets of a valve.  FIG. 72  thus shows an alternative to what is shown in other FIGS. like  FIG. 21 . This continuous design has flaps  540  built in to attach to the tops of the commissure posts  20  as described elsewhere in this specification. Another difference is radially inward contour or bulge of the free edge  61  of what will be each leaflet. This bulge gives the leaflets additional coaptation when the valve is closed. 
         [0188]      FIG. 73  illustrates the point that several of the principles of this invention can be applied to collapsible and re-expandable prosthetic valves that use leaflets that are not just from sheet material. For example, a bovine jugular or porcine aortic root (or individual leaflets)  550  can be attached to the commissure posts  20  of a valve stent. In other words, in the prosthetic valve shown in  FIG. 73 , the valving action is provided by the inclusion of an intact tissue valve (or leaflet cusps)  550  taken from an animal. 
         [0189]      FIGS. 74A-C  show several illustrative variations on what is shown in  FIG. 65 . For example, in  FIG. 74A  reference line  560   a  indicates the contour of one representative leaflet where it is attached (near its bottom or upstream portion) to the cuff  80  of the valve. (Apart from reference line  560   a ,  FIG. 74A  omits leaflets  60  and does not attempt to show the rear of the structure. Reference line  560   a  is shown primarily for purposes of explanation. This line does not itself depict structure, but rather is primarily just for geometric reference. The same is true for reference lines  560   b  and  560   c  in later FIGS.)  FIG. 74A  may show a balloon-expandable valve with a fabric cuff  80  and a porcine tissue buffer layer (hidden on the inside diameter (“ID”) of fabric  80 ) attached to about 75% of the height of the annulus portion  40  of the stent (i.e., the lower 75% of the annulus portion  40  height). (Stent portion  40  may be called the annulus portion because it is typically implanted in or near the annulus of the patient&#39;s native heart valve annulus.) Reference line  560   a  in  FIG. 74A  shows the lower portion of the leaflet attached straight across from the bottom eyelet  22  of one commissure post  20  to the next commissure post  20 . See also  FIG. 75 , which shows an example of such a leaflet  60  with reference line  560   a  superimposed on it. 
         [0190]      FIG. 74B  may show a self-expanding valve with the fabric cuff  80  and porcine tissue buffer (hidden on ID of the fabric) attached to the full height of the annulus portion  40  of the stent. As indicated by the reference line  560   b , a typical leaflet  60  is attached part of the way up the posts  20 , and the belly section of the leaflet gradually contours (curves) toward the stent base below the posts (see also  FIGS. 76A-B , which are discussed below). 
         [0191]      FIG. 74C  may show a self-expanding valve with the fabric cuff  80  on the outside diameter (“OD”) of the stent and porcine tissue buffer (not visible) on the ID of the stent. (Note that  FIG. 74C  shows cuff  80  as though transparent, and that this FIG. omits depiction of the sutures that are typically used to secure cuff  80  to the stent frame.) As shown by the reference line  560   c , a typical leaflet  60  in this case is attached near the bottom of the posts  20 , and the leaflet belly section gradually contours toward the stent base, at which point it can be attached to the base of the stent, cuff  80 , and features like those shown in  FIGS. 66-68 . 
         [0192]      FIGS. 76A-B  show an illustrative variation of a commissure post  20  (e.g., as in  FIG. 63 ) and the matching leaflet  60  (e.g., as in  FIG. 74B ). From  FIGS. 76A-B  it can be seen how the leaflet  60  matches up with various features of the stent post  20  as described earlier (e.g., in connection with  FIG. 74B ). Note that the two bottom eyelets  23   e  are not needed for leaflet attachment, but are present for cuff  80  securement. Also, the pair of eyelets  23   d ′ are placed slightly farther apart than the eyelet pairs above to aid in the transition of the leaflet contour (curve). 
         [0193]      FIGS. 77A-G  illustrate several ways that leaflets can be assembled to other components of the valve. Whereas FIGS. like  69 A-B focus on the area of leaflet attachment to commissure posts  20 , FIGS. like  77 A-G can apply to leaflet attachment elsewhere than at commissure posts  20 . In each of these FIGS. the double vertical lines represent any desired arrangement and/or combination of elements like stent  10  (e.g., annulus portion  40 ), buffer layer  70 , and/or cuff layer  80 . Element  60  is leaflet material, element  90  is suture material, and element  500  is a reinforcing core (e.g., as in  FIGS. 69A-B ). The bottom portion  570  of a leaflet  570  can be folded and/or supported with core material  500  to create a stronger seam. This seam can then be secured to the cuff  80  and/or stent  10 / 40  via suture  90  using a variety of techniques. For example, the stitch  90  shown in  FIG. 77A  pierces through the layers of leaflet tissue  60 / 570  once and whips around the bottom. The stitch shown in  FIG. 77B  pierces through the layers of tissue  60 / 570  twice. A reinforced core  500  ( FIGS. 77C-F ) can be placed inside the folded leaflet  60 / 570 . The leaflet (main portion  60 ) can be folded between the cuff  80  and the core  500  as shown in  FIG. 77C . Alternatively, the main portion of the leaflet  60  can pass in front of the core  500  as shown in  FIG. 77D . With the addition of a core  500 , the leaflet  60  may not need to be folded at all, but may simply be attached to the front/back of the core as shown in  FIGS. 77E and 77F , respectively. Yet another option is to use a foldable core material  580 , by which to sandwich the end of the leaflet  60  as shown in  FIG. 77G . As noted earlier (e.g., in connection with  FIGS. 69A-B ), the material of a reinforcing core can be other tissue, polymer, metal and/or fabric. Thus a reinforcing core like  500  or  570  can be rigid (e.g., metal or the like) or soft (e.g., fabric, tissue, or the like). The reinforcement can run along dotted suture lines shown on the leaflets in some of the FIGS. herein (e.g., line  575  in  FIG. 76B ) or any portion of such a suture line. Rigid reinforcement members may have eyelets parallel and/or perpendicular to post  20  eyelets. 
         [0194]      FIGS. 78A and 78B  show some examples of suture patterns that may be used to attach leaflet flaps to commissure posts  20 . In  FIG. 78A  one suture  90  is used to attach a leaflet flap to a post  20 . Beginning at the bottom right eyelet, the suture  90  is temporarily anchored at or near  590  where a suture tail remains. Suture  90  then runs from the bottom eyelet  23  to the top (back and forth through successive eyelets and a leaflet flap (not shown)) and then returns back down the same side (again back and forth through successive eyelets and the above-mentioned leaflet flap). Suture  90  then crosses over near  590  to the other column of eyelets to repeat the same pattern. Ultimately the suture end is tied off to the suture tail at  590 . 
         [0195]    In the alternative shown in  FIG. 78B , each side of the post eyelets (i.e., the left side eyelets or the right side eyelets) are sutured independently (suture  90   a  starting from  590   a  on the left, and suture  90   b  starting from  590   b  on the right), and each suture is ultimately tied off to its own tail at  590   a  or  590   b , respectively. 
         [0196]    To some extent the appended claim terminology may differ from terminology used up to this point in this detailed description. Some specific examples of what certain claim terms refer to are as follows. Supporting structure  10 ; sheet-like, flexible, leaflet member  60 / 160 ; free edge portion of a leaflet  61 ; flexible chord across an interior of the supporting structure (see, for example, reference number  131  in  FIG. 18A  or  FIG. 20A ; such a chord is typically not a straight chord, but rather a loose and flexible chord); material of the leaflet beyond an end of the chord forming a flap  62 ; cylindrical surface defined by one of the inner and outer surfaces of the supporting structure (such cylindrical surfaces are abstract geometric shapes defined by what are earlier referred to, respectively, as the ID (inside diameter) and OD (outside diameter) of supporting structure  10 ; these cylindrical surfaces are not necessarily round, but may instead have other shapes such as oval, elliptical, etc.); suture  90 ; inner surface of the supporting structure (ID of supporting structure  10 ); outer surface of the supporting structure (OD of supporting structure  10 ); secured line portion(s)  67 / 170 / 250 / 300   b ; belly portion of the leaflet  63 / 190 / 310 ; additional material of the leaflet beyond the secured line portion away from the belly portion forming a second flap  64 / 240 / 270 / 62   b ; axial end of the supporting structure, e.g., lower end of structure  10  as viewed in  FIG. 1 a   ; sheet-like, flexible, buffer material  70 ; annularly spaced commissure posts  20   a - c ; cantilevered from other structure of the supporting structure, e.g., commissure posts  20  may have upper free end portions and are only attached to the remainder of supporting structure  10  below those upper free end portions (this cantilevering of the upper free end portions of the commissure posts gives the commissure posts what is sometimes referred to herein as independent flexibility, which means, for example, that the upper free end portion of a commissure post can flex radially inwardly and outwardly at least somewhat independently of other portions of supporting structure  10 ) (note that in  FIG. 65  the posts  20  are not cantilevered, but the entire stent frame flexes to reduce stress); commissure post bifurcated into two spaced apart members, e.g., the commissure post portions on opposite sides of notch or opening  24 ; annular, annularly collapsible and re-expandable substructures  42   a - c  that are spaced from one another along an axis about which the supporting structure is annular; linking members  44  that are substantially parallel to the above-mentioned axis and that interconnect the above-mentioned substructures  42   a - c ; sheet of flexible leaflet material  160  having a central opening  150  with three sides  61 ; leaflet-linking areas  180 ; the sheet  160  continues radially outwardly beyond at least a portion of at least one of the secured line portions  250  to form a flap  240 / 270 ; a plurality of members disposed in a zig-zag pattern, e.g.,  42   c , that extends in a direction that is annular of the supporting structure; at least two of the members (e.g., the two members that meet at  440 ) meeting at an apex  440  that points away from the supporting structure parallel to an axis about which the supporting structure is annular; a sheet of flexible material  70  and/or  80  secured to the supporting structure; a plurality of flexible leaflets  60 / 160 ; suture attachment  90  at the apex  440 ; the apex  440  includes an eyelet  21 ; an enlarged head  450  on the end of a reduced neck  452 ; a notch  460 ; the notch is narrowed near its entrance  462 . The examples for certain claim terms provided in this paragraph are only illustrative. As just one example of this, not all of the reference numbers that are used for certain features and elements in certain FIGS. are repeated in every FIG. for every reoccurrence of the same or similar features or elements. 
         [0197]    It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the number of cells employed in the stents in valves in accordance with the invention can be different from the numbers shown in the various illustrative embodiment described above.