Prosthetic valve with concentric frames

Abstract

A unitary flexible sheet (612) is folded to define (i) a panel (608); (ii) a first tab (606a), having a first-tab outer layer and a first-tab inner layer, and protruding away from the panel; and (iii) a second tab (606b), having a second-tab outer layer and a second-tab inner layer, and protruding away from the panel. A commissural portion of a first prosthetic leaflet (58a), and a commissural portion of a second prosthetic leaflet (58b) are disposed between the first-tab inner layer and the second-tab inner layer. A first stitching (632) is stitched through the inner layer of each tab, and the commissural portion of each leaflet. A second stitching (634) is stitched through the outer and inner layers of each tab, and the commissural portion of each leaflet. The first-tab outer layer and the second-tab outer layer cover the first stitching. Other embodiments are also described.

1 . Apparatus, comprising:
 a unitary flexible sheet, folded to define:
 a panel, having a first side facing in a first direction, and a second side that is opposite the first side; 
 a first tab, disposed on the first side of the panel, having a first-tab outer layer and a first-tab inner layer, and protruding in the first direction away from the panel; and 
 a second tab, disposed on the first side of the panel, having a second-tab outer layer and a second-tab inner layer, and protruding in the first direction away from the panel; 
   a first prosthetic leaflet having a first-leaflet commissural portion disposed between the first-tab inner layer and the second-tab inner layer;   a second prosthetic leaflet having a second-leaflet commissural portion disposed between the first-tab inner layer and the second-tab inner layer;   a first stitching, stitched through the first-tab inner layer, the first-leaflet commissural portion, the second-leaflet commissural portion, and the second-tab inner layer; and   a second stitching, stitched through the first-tab outer layer, the first-tab inner layer, the first-leaflet commissural portion, the second-leaflet commissural portion, the second-tab inner layer, and the second-tab outer layer,   
       wherein the first-tab outer layer and the second-tab outer layer cover the first stitching. 
     
     
         2 . The apparatus according to  claim 1 , further comprising an adhesive disposed on at least one stitching selected from the group consisting of: the first stitching, and the second stitching. 
     
     
         3 . The apparatus according to  claim 1 , wherein:
 the sheet is folded along a first-tab fold line to define the first-tab outer layer and the first-tab inner layer, and the first-tab fold line is closer to the first stitching than to the second stitching, and   the sheet is folded along a second-tab fold line to define the second-tab outer layer and the second-tab inner layer, and the second-tab fold line is closer to the first stitching than to the second stitching.   
     
     
         4 . The apparatus according to  claim 1 , wherein:
 the sheet is folded along a first-tab fold line to define the first-tab outer layer and the first-tab inner layer, and an angle between the first-tab fold line and the first stitching is smaller than an angle between the first-tab fold line and the second stitching, and   the sheet is folded along a second-tab fold line to define the second-tab outer layer and the second-tab inner layer, and an angle between the second-tab fold line and the first stitching is smaller than an angle between the second-tab fold line and the second stitching.   
     
     
         5 . The apparatus according to  claim 1 , further comprising a separate flexible sheet, sandwiched between the first-leaflet commissural portion and the second-leaflet commissural portion. 
     
     
         6 . The apparatus according to  claim 1 , further comprising a tubular frame that defines a lumen, wherein:
 the panel is disposed against an inner surface of the tubular frame, and   the first prosthetic leaflet and the second prosthetic leaflet are secured within the lumen by the flexible sheet being connected to the tubular frame.   
     
     
         7 . The apparatus according to any one of  claims 1 - 6 , further comprising a separate flexible sheet, disposed between the first-leaflet commissural portion and the second-leaflet commissural portion, the first stitching being stitched through the separate flexible sheet. 
     
     
         8 . The apparatus according to  claim 7 , wherein the second stitching is stitched through the separate flexible sheet. 
     
     
         9 . The apparatus according to any one of  claims 1 - 6 , wherein:
 the flexible sheet is a first flexible sheet, the first-leaflet commissural portion is a first first-leaflet commissural portion, and the second-leaflet commissural portion is a first second-leaflet commissural portion,   the first flexible sheet, the first first-leaflet commissural portion, and the first second-leaflet commissural portion are arranged to collectively define a first commissure,   the first leaflet has a second first-leaflet commissural portion,   the second leaflet has a second second-leaflet commissural portion,   the apparatus further comprises:
 a tubular frame that defines a lumen, 
 a second flexible sheet, 
 a third flexible sheet, and 
 a third prosthetic leaflet, having a first third-leaflet commissural portion and a second third-leaflet commissural portion, 
   the second second-leaflet commissural portion, the first third-leaflet commissural portion, and the second flexible sheet are arranged to collectively define a second commissure,   the second first-leaflet commissural portion, the second third-leaflet commissural portion, and the third flexible sheet are arranged to collectively define a third commissure,   the first commissure, the second commissure, the third commissure, the first leaflet, the second leaflet, and the third leaflet, are arranged to define a valvular assembly that is secured within the lumen by the first flexible sheet, the second flexible sheet, and the third flexible sheet being connected to the tubular frame, and   the valvular assembly is configured to facilitate upstream-to-downstream fluid flow through the lumen by the first, second, and third prosthetic leaflets opening, and to inhibit downstream-to-upstream fluid flow through the lumen by the first, second, and third prosthetic leaflets closing.   
     
     
         10 . The apparatus according to  claim 9 , wherein, for each of the commissures, the first tab and the second tab each defines a loose region, radially inward from the first stitching and the second stitching, that is loose with respect to the prosthetic leaflets that meet at the commissure. 
     
     
         11 . The apparatus according to  claim 9 , wherein the valvular assembly is configured such that, for each of the commissures, in response to the first, second, and third prosthetic leaflets opening, at least part of the first tab and at least part of the second tab move away from each other, and in response to the first, second, and third prosthetic leaflets closing, at least part of the first tab and at least part of the second tab move toward each other. 
     
     
         12 . The apparatus according to any one of  claims 1 - 6 , further comprising a tubular frame that is shaped to define a lumen, wherein the panel is secured against an inner surface of a tubular frame, such that (i) the first tab, the second tab, the first prosthetic leaflet, and the second prosthetic leaflet extend away from the panel into the lumen, and (ii) the first and second leaflets are arranged to facilitate upstream-to-downstream fluid flow through the lumen, and to inhibit downstream-to-upstream fluid flow through the lumen. 
     
     
         13 . The apparatus according to  claim 12 , wherein the sheet defines a plurality of flaps extending from the panel, and wherein the panel is secured against the inner surface of the tubular frame by each flap of the plurality of flaps being folded around a respective component of the tubular frame. 
     
     
         14 . The apparatus according to  claim 13 , wherein each flap of the plurality of flaps is stitched to the respective component of the tubular frame. 
     
     
         15 . The apparatus according to  claim 12 , wherein the sheet is folded to define a first cushion at a downstream edge of the first tab, and a second cushion at a downstream edge of the second tab. 
     
     
         16 . The apparatus according to  claim 15 , wherein the first cushion and the second cushion are disposed downstream of the first prosthetic leaflet and the second prosthetic leaflet. 
     
     
         17 . The apparatus according to  claim 15 , wherein neither the first cushion nor the second cushion are in contact with the first prosthetic leaflet or the second prosthetic leaflet. 
     
     
         18 . The apparatus according to  claim 15 , wherein the first tab defines a downstream opening between the first-tab inner layer and the first-tab outer layer, and the second tab portion defines a downstream opening between the second-tab inner layer and the second-tab outer layer. 
     
     
         19 . The apparatus according to  claim 15 , wherein:
 the sheet defines a first-tab fold and a second-tab fold,   the first cushion comprises the first-tab fold, folded between the first-tab inner layer and the first-tab outer layer, and   the second cushion comprises the second-tab fold, folded between the second-tab inner layer and the second-tab outer layer.   
     
     
         20 . The apparatus according to  claim 19 , wherein:
 the first-tab fold is a first-tab outer fold, continuous with the first-tab outer layer,   the second-tab fold is a second-tab outer fold, continuous with the second-tab outer layer,   the sheet further defines:
 a first-tab inner fold, continuous with the first-tab inner layer, and 
 a second-tab inner fold, continuous with the second-tab inner layer, the first cushion comprises: 
 the first-tab outer fold, folded between the first-tab outer layer and the first-tab inner fold, and 
 the first-tab inner fold, folded between the first-tab inner layer and the first-tab outer fold, and 
   the second cushion comprises:
 the second-tab outer fold, folded between the second-tab outer layer and the second-tab inner fold, and 
 the second-tab inner fold, folded between the second-tab inner layer and the second-tab outer fold. 
   
     
     
         21 . The apparatus according to any one of  claims 1 - 6 , wherein:
 the first stitching is stitched along a first stitch line,   the second stitching is stitched along a second stitch line, and   the first stitch line and the second stitch line diverge from each other at 10-45 degrees.   
     
     
         22 . The apparatus according to  claim 21 , wherein the first stitch line and the second stitch line diverge from each other at 10-30 degrees. 
     
     
         23 . The apparatus according to  claim 22 , wherein the first stitch line and the second stitch line diverge from each other at 15-25 degrees. 
     
     
         24 . The apparatus according to  claim 23 , wherein the first stitch line and the second stitch line diverge from each other at 20 degrees. 
     
     
         25 . Apparatus, comprising:
 a unitary flexible sheet that, in an unfolded state of the sheet, defines:
 a panel portion at a medial region of the sheet, 
 a first tab portion disposed peripherally to the panel, and having (i) a first part, and (ii) a second part that is disposed peripherally to the first part of the first tab portion, and 
 a second tab portion disposed peripherally to the panel opposite the first tab portion, and having (i) a first part, and (ii) a second part that is disposed peripherally to the first part of the second tab portion, 
   
       the sheet being folded into a folded state in which the sheet defines:
 a panel, defined by the panel portion, having a first side facing in a first direction, and a second side that is opposite the first side; 
 a first tab, defined by the first tab portion, the first tab being disposed on the first side of the panel, and having:
 a first-tab inner layer defined by the first part of the first tab portion extending away from the panel in the first direction, and 
 a second-tab outer layer defined by the second part of the first tab portion being folded back over the first part of the first tab portion, and extending back toward the panel; 
 
 a second tab, defined by the second tab portion, the second tab being disposed on the first side of the panel, and having:
 a second-tab inner layer defined by the first part of the second tab portion extending away from the panel in the first direction, and 
 a second-tab outer layer defined by the second part of the second tab portion being folded back over the first part of the second tab portion, and extending back toward the panel; 
 
 a first prosthetic leaflet having a first-leaflet commissural portion sandwiched between the first-tab inner layer and the second-tab inner layer; 
 a second prosthetic leaflet having a second-leaflet commissural portion sandwiched between the first-tab inner layer and the second-tab inner layer. 
 
     
     
         26 . The apparatus according to  claim 25 , further comprising a stitching, stitched through the first-tab inner layer, the first-leaflet commissural portion, the second-leaflet commissural portion, and the second-tab inner layer. 
     
     
         27 . The apparatus according to  claim 26 , wherein the first-tab outer layer and the second-tab outer layer cover the stitching. 
     
     
         28 . The apparatus according to  claim 27 , wherein the stitching is a first stitching, and wherein the apparatus further comprises a second stitching, stitched through the first-tab outer layer, the first-tab inner layer, the first-leaflet commissural portion, the second-leaflet commissural portion, the second-tab inner layer, and the second-tab outer layer. 
     
     
         29 . A method for use with a flexible sheet that, in an unfolded state of the sheet, defines a panel at a medial region of the sheet, a first tab portion disposed peripherally to the panel, and a second tab portion disposed peripherally to the panel opposite the first tab portion, the method comprising:
 sandwiching, between the first tab portion and the second tab portion, (i) a first commissural portion of a first prosthetic leaflet, and (ii) a second commissural portion of a second prosthetic leaflet;   attaching the first tab portion and the second tab portion to the flexible sheet by stitching a first stitching through the first tab-portion, the first commissural portion, the second commissural portion, and the second tab-portion;   subsequently, covering the first stitching by:
 folding the first tab portion back against itself to form the first tab portion into a first tab having first-tab outer layer and a first-tab inner layer, such that the first-tab inner layer is sandwiched between the first-tab outer layer and the first commissural portion, and 
 folding the second tab portion back against itself to form the second tab portion into a second tab having a second-tab outer layer and a second-tab inner layer, such that the second-tab inner layer is sandwiched between the second-tab outer layer and the second commissural portion; and 
   subsequently, stitching a second stitching through the first-tab outer layer, the first-tab inner layer, the first commissural portion, the second commissural portion, the second-tab inner layer, and the second-tab outer layer.   
     
     
         30 . The method according to  claim 29 , wherein the step of sandwiching comprises sandwiching a separate flexible sheet between the first commissural portion and the second commissural portion. 
     
     
         31 . The method according to  claim 29 , wherein stitching the first stitching comprises stitching the first stitching through (i) the first tab-portion, (ii) the first commissural portion, (iii) a separate flexible sheet disposed between the first commissural portion and the second commissural portion, (iv) the second commissural portion, and (v) the second tab-portion. 
     
     
         32 . The method according to  claim 29 , wherein the step of sandwiching comprises sandwiching a fabric divider between the first tab portion and the second tab portion. 
     
     
         33 . The method according to any one of  claims 29 - 32 , wherein the step of sandwiching comprises sandwiching a separate flexible sheet between the first commissural portion and the second commissural portion, and wherein stitching the first stitching comprises stitching the first stitching through the separate flexible sheet. 
     
     
         34 . The method according to  claim 33 , wherein stitching the second stitching comprises stitching the second stitching through the separate flexible sheet. 
     
     
         35 . The method according to any one of  claims 29 - 32 , wherein the flexible sheet is a first flexible sheet, and the steps of sandwiching, attaching, covering, and stitching the second stitching, are steps in assembling the first flexible sheet into a first commissure at which the first prosthetic leaflet and the second prosthetic leaflet meet, and wherein the method further comprises:
 assembling a valvular assembly that includes the first commissure, a second commissure, a third commissure, the first prosthetic leaflet, the second prosthetic leaflet, and a third prosthetic leaflet, by:
 assembling a second flexible sheet into a second commissure at which the second prosthetic leaflet and a third prosthetic leaflet meet; and 
 assembling a third flexible sheet into a third commissure at which the third prosthetic leaflet and the first prosthetic leaflet meet; and 
   subsequently to assembling the valvular assembly, securing the valvular assembly within a lumen defined by a tubular frame, such that:
 the first, second, and third prosthetic leaflets are arranged within the lumen to facilitate upstream-to-downstream fluid flow through the lumen by the first, second, and third prosthetic leaflets opening, and to inhibit downstream-to-upstream fluid flow through the lumen by the first, second, and third prosthetic leaflets closing, and 
 for each of the commissures:
 the panel is disposed against an inner surface of the tubular frame, and 
 the first tab and the second tab extend away from the panel into the lumen. 
 
   
     
     
         36 . The method according to  claim 35 , wherein for each of the commissures, assembling the flexible sheet into the commissure comprises assembling the flexible sheet into the commissure such that the first tab and the second tab each define a loose region, radially inward from the first stitching and the second stitching, that is loose with respect to the prosthetic leaflets that meet at the commissure. 
     
     
         37 . The method according to  claim 35 , wherein securing the valvular assembly within the lumen comprises securing the valvular assembly within the lumen such that, for each of the commissures, in response to the first, second, and third prosthetic leaflets opening, at least part of the first tab and at least part of the second tab move away from each other, and in response to the first, second, and third prosthetic leaflets closing, at least part of the first tab and at least part of the second tab move toward each other. 
     
     
         38 . The method according to any one of  claims 29 - 32 , further comprising, subsequently to stitching the second stitching, securing the panel against an inner surface of a tubular frame, such that (i) the first tab, the second tab, the first prosthetic leaflet, and the second prosthetic leaflet extend away from the panel into a lumen defined by the tubular frame, and (ii) the first and second leaflets are arranged to facilitate upstream-to-downstream fluid flow through the lumen, and to inhibit downstream-to-upstream fluid flow through the lumen. 
     
     
         39 . The method according to  claim 38 , wherein the sheet, in its unfolded state, further defines a plurality of flaps disposed peripherally to the panel, and wherein securing the panel against the inner surface of the tubular frame comprises folding each flap of the plurality of flaps around a respective component of the tubular frame. 
     
     
         40 . The method according to  claim 39 , wherein securing the panel against the inner surface of the tubular frame further comprises stitching each flap of the plurality of flaps to the respective component of the tubular frame. 
     
     
         41 . The method according to  claim 38 , further comprising (i) forming a first cushion by folding a first-tab fold in a downstream edge of the first tab portion, and (ii) forming a second cushion by folding a second-tab fold in a downstream edge of the second tab portion. 
     
     
         42 . The method according to  claim 41 , wherein forming the first cushion and forming the second cushion comprise forming the first cushion and forming the second cushion such that, after the panel has been secured against the inner surface of the inner frame, the first cushion and the second cushion are disposed downstream of the first prosthetic leaflet and the second prosthetic leaflet. 
     
     
         43 . The method according to  claim 41 , wherein forming the first cushion and forming the second cushion comprise forming the first cushion and forming the second cushion such that, after the panel has been secured against the inner surface of the inner frame, neither the first cushion nor the second cushion are in contact with the first prosthetic leaflet or the second prosthetic leaflet. 
     
     
         44 . The method according to  claim 41 , wherein forming the first cushion comprises forming the first cushion such that, after the panel has been secured against the inner surface of the inner frame, the first tab defines a downstream opening between the first-tab inner layer and the first-tab outer layer, and forming the second cushion comprises forming the second cushion such that, after the panel has been secured against the inner surface of the inner frame, the second tab portion defines a downstream opening between the second-tab inner layer and the second-tab outer layer. 
     
     
         45 . The method according to  claim 41 , wherein:
 forming the first cushion comprises folding the first-tab fold such that, after the panel has been secured against the inner surface of the inner frame, the first-tab fold is disposed between the first-tab inner layer and the first-tab outer layer, and   forming the second cushion comprises folding the second-tab fold such that, after the panel has been secured against the inner surface of the inner frame, the second-tab fold is disposed between the second-tab inner layer and the second-tab outer layer.   
     
     
         46 . The method according to  claim 45 , wherein:
 the first-tab fold is a first-tab outer fold,   the second-tab fold is a second-tab outer fold,   forming the first cushion further comprises folding a first-tab inner fold in the downstream edge of the first tab portion, such that after the panel has been secured against the inner surface of the inner frame:
 the first-tab outer fold is continuous with the first-tab outer layer, and is disposed between the first-tab outer layer and the first-tab inner fold, and 
 the first-tab inner fold is continuous with the first-tab inner layer, and is disposed between the first-tab inner layer and the first-tab outer fold, and 
   forming the second cushion further comprises folding a second-tab inner fold in the downstream edge of the second tab portion, such that after the panel has been secured against the inner surface of the inner frame:
 the second-tab outer fold is continuous with the second-tab outer layer, and is disposed between the second-tab outer layer and the second-tab inner fold, and 
 the second-tab inner fold is continuous with the second-tab inner layer, and is disposed between the second-tab inner layer and the second-tab outer fold. 
   
     
     
         47 . The method according to  claim 41 , wherein forming the first-tab cushion comprises forming the first-tab cushion prior to folding the first tab-portion back against itself, and forming the second-tab cushion comprises forming the second-tab cushion prior to folding the second tab-portion back against itself. 
     
     
         48 . The method according to  claim 47 , wherein forming the first-tab cushion and forming the second-tab cushion comprises forming the first-tab cushion and forming the second-tab cushion subsequently to stitching the first stitching. 
     
     
         49 . The method according to any one of  claims 29 - 32 , wherein:
 the first tab portion defines a plurality of first-tab portion suture holes arranged in:
 a first row, 
 a second row, and 
 a third row, and 
   the second tab portion defines a plurality of second-tab portion suture holes arranged in:
 a fourth row, 
 a fifth row, and 
 a sixth row, and 
   stitching the first stitching through the first tab-portion, the first commissural portion, the second commissural portion, and the second tab-portion comprises stitching the first stitching through the second row, the first commissural portion, the second commissural portion, and the fifth row.   
     
     
         50 . The method according to  claim 49 , wherein, in the unfolded state of the sheet, the first row and the third row diverge at a diverging angle, and wherein folding the first tab portion back against itself comprises folding the first tab portion along a fold line such that an angle between the fold line and the first row is substantially equal to an angle between the fold line and the third row. 
     
     
         51 . The method according to  claim 50 , wherein folding the first tab portion back against itself comprises folding the first tab portion such that an angle between the fold line and the second row is smaller than both (i) the angle between the fold line and the first row, and (ii) the angle between the fold line and the third row. 
     
     
         52 . The method according to  claim 49 , wherein:
 folding the first tab portion back against itself comprises folding the first tab portion back against itself such that the first-tab outer layer covers the second row, and the third row is aligned with the first row, and   folding the second tab portion back against itself comprises folding the second tab portion back against itself such that the second-tab outer layer covers the fifth row, and the sixth row is aligned with the fourth row.   
     
     
         53 . The method according to  claim 49 , wherein stitching the second stitching through the first-tab outer layer, the first-tab inner layer, the first commissural portion, the second commissural portion, the second-tab inner layer, and the second-tab outer layer comprises stitching the second stitching through the third row, the first row, the first commissural portion, the second commissural portion, the fourth row, and the sixth row. 
     
     
         54 . The method according to any one of  claims 29 - 32 , further comprising, subsequently to stitching the second stitching, bringing the panel closer to the first prosthetic leaflet and the second prosthetic leaflet. 
     
     
         55 . The method according to  claim 54 , wherein bringing the panel closer comprises moving an unstitched part of the first commissural portion away from an unstitched part of the second commissural portion. 
     
     
         56 . The method according to  claim 54 , wherein bringing the panel closer comprises sandwiching unstitched parts of the first commissural portion and unstitched parts of the second commissural portion between the panel and another region of the sheet. 
     
     
         57 . The method according to  claim 54 , wherein bringing the panel closer to the first prosthetic leaflet and the second prosthetic leaflet comprises flattening the panel. 
     
     
         58 . The method according to  claim 57 , wherein the step of sandwiching comprises bending the panel. 
     
     
         59 . Apparatus, comprising:
 a unitary flexible sheet, folded to define:
 a panel, defining a plane, and having a first side facing in a first direction away from the plane, and a second side that is opposite the first side; 
 a first tab, disposed on the first side of the panel, and protruding in the first direction away from the panel; and 
 a second tab, disposed on the first side of the panel, and protruding in the first direction away from the panel; 
   a first prosthetic leaflet having a first-leaflet commissural portion disposed between the first tab and the second tab;   a second prosthetic leaflet having a second-leaflet commissural portion disposed between the first tab and the second tab;   
       wherein:
 at the first tab, the sheet is folded to define a first cushion at a downstream edge of the first tab, the first cushion being configured and positioned to inhibit deflection of a downstream portion of the first prosthetic leaflet away from the second prosthetic leaflet and toward the plane, and 
 at the second tab, the sheet is folded to define a second cushion at a downstream edge of the second tab, the second cushion being configured and positioned to inhibit deflection of a downstream portion of the second prosthetic leaflet away from the first prosthetic leaflet and toward the plane. 
 
     
     
         60 . The apparatus according to  claim 59 , further comprising a separate flexible sheet, sandwiched between the first-leaflet commissural portion and the second-leaflet commissural portion. 
     
     
         61 . The apparatus according to  claim 59 , wherein the first cushion and the second cushion are disposed downstream of the first prosthetic leaflet and the second prosthetic leaflet. 
     
     
         62 . The apparatus according to  claim 59 , wherein:
 the sheet is folded such that the first tab has a first-tab outer layer and a first-tab inner layer, and the second tab has a second-tab outer layer and a second-tab inner layer,   the first-leaflet commissural portion is disposed between the first-tab inner layer and the second-tab inner layer, and   the second-leaflet commissural portion is disposed between the first-tab inner layer and the second-tab inner layer.   
     
     
         63 . The apparatus according to  claim 62 , wherein the first tab defines a downstream opening between the first-tab inner layer and the first-tab outer layer, and the second tab defines a downstream opening between the second-tab inner layer and the second-tab outer layer. 
     
     
         64 . The apparatus according to  claim 62 , wherein:
 the sheet defines a first-tab fold and a second-tab fold,   the first cushion comprises the first-tab fold, folded between the first-tab inner layer and the first-tab outer layer, and   the second cushion comprises the second-tab fold, folded between the second-tab inner layer and the second-tab outer layer.   
     
     
         65 . The apparatus according to  claim 64 , wherein the first-tab fold is secured by stitching, and the second-tab fold is secured by stitching. 
     
     
         66 . The apparatus according to  claim 64 , wherein:
 the first-tab fold is a first-tab outer fold, continuous with the first-tab outer layer,   the second-tab fold is a second-tab outer fold, continuous with the second-tab outer layer,   the sheet further defines:
 a first-tab inner fold, continuous with the first-tab inner layer, and 
 a second-tab inner fold, continuous with the second-tab inner layer, the first cushion comprises: 
 the first-tab outer fold, folded between the first-tab outer layer and the first-tab inner fold, and 
 the first-tab inner fold, folded between the first-tab inner layer and the first-tab outer fold, and 
   the second cushion comprises:
 the second-tab outer fold, folded between the second-tab outer layer and the second-tab inner fold, and 
 the second-tab inner fold, folded between the second-tab inner layer and the second-tab outer fold. 
   
     
     
         67 . A method, comprising:
 folding a unitary flexible sheet to define:
 a panel, defining a plane, and having a first side facing in a first direction away from the plane, and a second side that is opposite the first side, 
 a first tab, disposed on the first side of the panel, and protruding in the first direction away from the panel, and 
 a second tab, disposed on the first side of the panel, and protruding in the first direction away from the panel; 
   securing, between the first tab and the second tab:
 a first-leaflet commissural portion of a first prosthetic leaflet, and 
 a second-leaflet commissural portion of a second prosthetic leaflet; 
   at the first tab, folding the sheet to define a first cushion at a downstream edge of the first tab, the first cushion being configured and positioned to inhibit deflection of a downstream portion of the first prosthetic leaflet away from the second prosthetic leaflet and toward the plane; and   at the second tab, folding the sheet to define a second cushion at a downstream edge of the second tab, the second cushion being configured and positioned to inhibit deflection of a downstream portion of the second prosthetic leaflet away from the first prosthetic leaflet and toward the plane.   
     
     
         68 . The method according to  claim 67 , further comprising sandwiching a separate flexible sheet between the first-leaflet commissural portion and the second-leaflet commissural portion. 
     
     
         69 . The method according to  claim 67 , wherein:
 folding the sheet to define the first cushion comprises folding the sheet to define the first cushion such that the first cushion is disposed downstream of the first prosthetic leaflet and the second prosthetic leaflet, and   folding the sheet to define the second cushion comprises folding the sheet to define the second cushion such that the second cushion is disposed downstream of the first prosthetic leaflet and the second prosthetic leaflet.   
     
     
         70 . The method according to  claim 67 , wherein:
 folding the sheet to define the first tab comprises folding the sheet such that the first tab has a first-tab outer layer and a first-tab inner layer,   folding the sheet to define the second tab comprises folding the sheet such that the second tab has a second-tab outer layer and a second-tab inner layer,   securing the first-leaflet commissural portion and the second-leaflet commissural portion between the first tab and the second tab comprises securing the first-leaflet commissural portion and the second-leaflet commissural portion between the first-tab inner layer and the second-tab inner layer.   
     
     
         71 . The method according to  claim 70 , wherein:
 folding the sheet such that the first tab has a first-tab outer layer and a first-tab inner layer comprises folding the sheet such that the first tab defines a downstream opening between the first-tab inner layer and the first-tab outer layer, and   folding the sheet such that the second tab has a second-tab outer layer and a second-tab inner layer comprises folding the sheet such that the second tab defines a downstream opening between the second-tab inner layer and the second-tab outer layer.   
     
     
         72 . The method according to  claim 70 , wherein:
 folding the sheet to define the first cushion comprises folding a first-tab fold of the sheet between the first-tab inner layer and the first-tab outer layer, and   folding the sheet to define the second cushion comprises folding a second-tab fold of the sheet between the second-tab inner layer and the second-tab outer layer.   
     
     
         73 . The method according to  claim 72 , further comprising securing the first-tab fold by stitching, and folding the second-tab fold by stitching. 
     
     
         74 . The method according to  claim 72 , wherein:
 the first-tab fold is a first-tab outer fold, continuous with the first-tab outer layer,   the second-tab fold is a second-tab outer fold, continuous with the second-tab outer layer,   the sheet further defines:
 a first-tab inner fold, continuous with the first-tab inner layer, and 
 a second-tab inner fold, continuous with the second-tab inner layer, folding the sheet to define the first cushion comprises: 
 folding the first-tab outer fold between the first-tab outer layer and the first-tab inner fold, and 
 folding the first-tab inner fold between the first-tab inner layer and the first-tab outer fold, and 
   folding the sheet to define the second cushion comprises:
 folding the second-tab outer fold between the second-tab outer layer and the second-tab inner fold, and 
 folding the second-tab inner fold between the second-tab inner layer and the second-tab outer fold. 
   
     
     
         75 . Apparatus for use with a prosthetic valve, the apparatus comprising a connector, the connector comprising a flexible sheet that is folded to define:
 a panel, having a first side facing in a first direction, and a second side that is opposite the first side;   a leaflet receptacle, disposed on the first side of the panel, and protruding in the first direction away from the panel; and   a plurality of flaps, each flap folded about a respective fold axis such that at least part of each flap is disposed on the second side of the panel.