Patent Description:
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two common types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve may first be collapsed or crimped to reduce its circumferential size and diameter.

When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating use range. For balloon-expandable valves, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn. <CIT> discloses a prosthetic heart valve. <CIT> discloses a leaflet-sensitive valve fixation member. <CIT> discloses a collapsible prosthetic heart valve. <CIT> discloses a leaflet in configuration for function in various shapes and sizes.

The present invention is defined by the scope of the appended claims.

According to the invention, a prosthetic heart valve includes a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of commissure features. The heart valve further includes a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the leaflets having a free edge having a first end and a second end, and a second edge secured to the cuff, the second edge having a first end, a second end, a first folded portion adjacent the first end, a second folded portion adjacent the second end, and an unfolded portion between the first and second folded portions. The first and second folded portions couple the leaflet to ones of the commissure features.

In some examples, a prosthetic valve assembly includes a substantially cylindrical cuff, a plurality of leaflets disposed inside the cuff, a reverse-running stitch coupled to unfolded portions of each of the leaflets, the reverse-running stitch having an outer part disposed between the cuff and each of the leaflets and an inner part disposed on an opposite side of each of the leaflets and a suture for coupling the cuff to each of the leaflets.

Various examples of the present invention are disclosed herein with reference to the drawings, wherein:.

Various examples of the present invention will now be described with reference to the appended drawings. It is to be appreciated that these drawings depict only some examples and are therefore not to be considered limiting of its scope.

As used herein, the term "proximal," when used in connection with a prosthetic heart valve, refers to the end of the heart valve closest to the heart when the heart valve is implanted in a patient, whereas the term "distal," when used in connection with a prosthetic heart valve, refers to the end of the heart valve farthest from the heart when the heart valve is implanted in a patient. When used in connection with devices for delivering a prosthetic heart valve into a patient, the terms "proximal" and "distal" are to be taken as relative to the user of the delivery devices. "Proximal" is to be understood as relatively close to the user, and "distal" is to be understood as relatively farther away from the user. Also, as used herein, the words "substantially," "generally" and "about" are intended to mean that slight variations from absolute are included within the scope of the structure or process recited.

<FIG> shows a typical collapsible prosthetic heart valve <NUM>. The prosthetic heart valve <NUM> is designed to replace the function of a native aortic valve of a patient. Examples of collapsible prosthetic heart valves are described in International Patent Application Publication No. <CIT>; <CIT>; and <CIT>. As discussed in detail below, the prosthetic heart valve has an expanded condition and a collapsed condition. Although the invention is described herein as applied to a prosthetic heart valve for replacing a native aortic valve, the invention is not so limited, and may be applied to prosthetic valves for replacing other types of cardiac valves.

The prosthetic heart valve <NUM> includes a stent or frame <NUM>, which may be wholly or partly formed of any biocompatible material, such as metals, synthetic polymers, or biopolymers capable of functioning as a stent. Suitable biopolymers include, but are not limited to, elastin, and mixtures or composites thereof. Suitable metals include, but are not limited to, cobalt, titanium, nickel, chromium, stainless steel, and alloys thereof, including nitinol. Suitable synthetic polymers for use as a stent include, but are not limited to, thermoplastics, such as polyolefins, polyesters, polyamides, polysulfones, acrylics, polyacrylonitriles, polyetheretherketone (PEEK), and polyaramides. The stent <NUM> may have an annulus section <NUM>, an aortic section (not shown), and an intermediate section (not shown) disposed between the annulus and aortic sections. Each of the annulus section <NUM>, the intermediate section, and the aortic section of the stent <NUM> includes a plurality of cells <NUM> connected to one another around the stent. The annulus section <NUM>, the intermediate section, and the aortic section of the stent <NUM> may include one or more annular rows of cells <NUM> connected to one another. For instance, the annulus section <NUM> may have two annular rows of cells <NUM>. When the prosthetic heart valve <NUM> is in the expanded condition, each cell <NUM> may be substantially diamond shaped. Regardless of its shape, each cell <NUM> is formed by a plurality of struts <NUM>. For example, a cell <NUM> may be formed by four struts <NUM>.

The stent <NUM> may include commissure features or commissure posts (not shown) connecting at least two cells <NUM> in the longitudinal direction of the stent <NUM>. The commissure features may include eyelets that facilitate the suturing of a valve assembly <NUM> to the sent <NUM>.

The prosthetic heart valve <NUM> also includes a valve assembly <NUM> attached inside the annulus section <NUM> of the stent <NUM>. <CIT>, and <CIT> describe suitable valve assemblies. The valve assembly <NUM> may be wholly or partly formed of any suitable biological material, fabric or a polymer. Examples of biological materials suitable for the valve assembly <NUM> include, but are not limited to, porcine or bovine pericardial tissue. Examples of polymers suitable for the valve assembly <NUM> include, but are not limited to, polyurethane and polyester.

The valve assembly <NUM> may include a cuff <NUM> disposed on the luminal surface of annulus section <NUM>, on the abluminal surface of the annulus section, or on both surfaces, and the cuff may cover all or part of either or both of the luminal and abluminal surfaces of the annulus section. <FIG> shows cuff <NUM> disposed on the luminal surface of annulus section <NUM> so as to cover part of the annulus section while leaving another part thereof uncovered. In addition to the materials for forming valve assembly <NUM> noted above, the cuff <NUM> and/or any of the sutures described herein may include ultra-high-molecular-weight polyethylene. The valve assembly <NUM> may further include a plurality of leaflets <NUM> which collectively function as a one-way valve.

The cuff <NUM> of the prosthetic heart valve <NUM> of <FIG> tends to experience relatively high strain and/or stress at certain locations. In such heart valves <NUM>, the pressure of blood that leaflets <NUM> keep from flowing into the heart may subject leaflets <NUM> to a load in the direction indicated by arrow L, shown in <FIG>. This load may cause high stress and/or strain on the cuff and/or leaflets. Moreover, a typical load may cause wear over time. To manage the increased stress and strain on the cuff <NUM>, some conventional heart valves <NUM> have made the cuff thicker. However, thicker cuffs generally lead to a larger heart valve that is more difficult to deliver and implant.

One method of redistributing the load has been to attach the leaflets to the struts. Alternatively, it may be advantageous to attach the leaflets substantially entirely to the cuff and not to the struts. In certain procedures, collapsible valves may be implanted in a native valve annulus without first resecting the native valve leaflets. Additionally, other patients may have uneven calcification, bi-cuspid disease, and/or valve insufficiency.

To reduce adverse events, (e.g., (<NUM>) perivalvular leakage (PV leak), (<NUM>) valve migration, (<NUM>) mitral valve impingement, (<NUM>) conduction system disruption, (<NUM>) coronary blockage, etc.) adequate sealing and anchoring without excessive radial force may be advantageous. Examples of the present invention which attach the leaflets mainly to the cuff are able to achieve better coaptation of the leaflets, reducing the risk of leakage.

Moreover, the annulus section of the prosthetic valve may have a generally regular cylindrical shape by which is meant that the structure has a generally circular cross-section with a substantially constant diameter along its length. When placed in the annulus of a native heart valve, such as, for example, the tricuspid aortic valve, and expanded, a substantially fluid-tight fit should result. However, the native valve annulus may not be circular, and, in fact, may vary from patient to patient, as may the shape of the aortic sinus or aorta, the angle of the junction between the valve annulus and the aortic sinus, and other local anatomical features. When a prosthetic valve is deployed and expanded, it is advantageous that it accommodates these anatomical variations in order to function properly. This may result in distortion of the shape of the stent and/or valve assembly, and the repositioning of leaflets relative to one another, which can affect the coaptation of these leaflets.

As the stent of a collapsible prosthetic heart valve distorts during implantation, during beating of the heart, or because of irregularities in the patient's anatomy or the condition of the native valve, such distortion may be translated to the valve assembly, such that not all of the valve leaflets meet to form effective coaptation junctions. This can result in leakage or regurgitation and other inefficiencies which can reduce cardiac performance. Moreover, if the prosthetic valve is not placed optimally and the valve leaflets are not coapting as intended, other long term effects, such as uneven wear of the individual leaflets or increased stress on the cuff and/or stent, may be postulated.

Prosthetic valves in accordance with certain aspects of the present invention, however, can function properly notwithstanding the distortion of the stent and/or valve assembly because the leaflets are substantially attached to the cuff and not to the stent. Without wishing to be held to any particular theory, it is believed that a valve design having leaflets mostly sewn to the cuff may be better able to adjust to less than perfect annulus geometry. Such leaflet-cuff arrangements may be more insulated from imperfect geometry-induced stresses on the struts than those arrangements having the leaflets completely or predominantly sewn to the stent. Thus, the possibility of uneven wear due to anatomical variations is greatly reduced by attaching the leaflets entirely or predominantly to the cuff.

Moreover, by sewing the leaflets to the cuff and not to the struts, greater flexibility is afforded in positioning the leaflets and in varying the height, width and shape of the leaflets. Specifically, because the leaflets in conventional heart valves are attached to the struts, the leaflet shape and positioning is limited by the location of the struts. In contrast, suturing patterns may be varied with greater benefits when the leaflets are attached predominantly to the cuff.

Having outlined some of the benefits of a leaflet-cuff attachment, the features of this example will be described in connection with the prosthetic heart valve <NUM> shown in <FIG>. It will also be noted that while the inventions herein described are predominately discussed in terms of a tricuspid valve and a stent having a shape as illustrated in <FIG>, the valve could be a bicuspid valve, such as the mitral valve, or include more than three leaflets, and the stent could have different shapes, such as a flared or conical annulus section, a less-bulbous aortic section, and the like, and a differently shaped intermediate section.

In attaching the plurality of leaflets, each leaflet <NUM> may be first attached to the stent <NUM> by suturing through the eyelets of commissure features <NUM>. Additional examples of leaflet-commissure feature attachments are disclosed in <CIT>. In addition to the commissure features <NUM>, the plurality of leaflets may be attached to the cuff <NUM> as described below.

<FIG> and <FIG> illustrate one such example in which the leaflets <NUM> have been attached by suturing substantially entirely to the cuff <NUM>. In the illustrated example, the leaflets <NUM> are coupled to the cuff <NUM> after they have been attached to the commissure features <NUM>. It will be understood, however, that the order of attachment may be changed or varied as necessary by those skilled in the art.

<FIG> illustrate a cuff <NUM> and one or more leaflets <NUM>. Each leaflet <NUM> includes a proximal end <NUM> for attachment to the cuff <NUM> and a free distal end <NUM> for coapting with the other leaflets to form a closed valve. As seen in <FIG>, each leaflet <NUM> may be folded upon itself at the proximal end <NUM> to form a belly flap <NUM> for attaching the leaflet to the cuff <NUM>. The belly flap <NUM> may be formed by folding the proximal end of the leaflet <NUM> once over itself toward the cuff <NUM> so that the belly flap is disposed between a portion of the leaflet and the cuff. The width x of the belly flap <NUM> between fold line 356a and free edge 356b may vary from valve to valve, and also within a valve. For example, the belly flap <NUM> may have a width x between about <NUM> and about <NUM>. Variants of the belly flap <NUM> are also contemplated herein. For example, the belly flap <NUM> may be formed by folding the leaflet <NUM> more than once (e.g., twice, thrice or more). Additionally, the belly flap <NUM> may be formed along only a portion of the proximal end of the leaflet <NUM> if the entire proximal end will not be sutured to the cuff <NUM>. Still further, the belly flap <NUM> may be formed by folding the proximal end of the leaflet <NUM> away from the cuff <NUM>, rather than toward the cuff as described above.

After folding each leaflet <NUM> to form a belly flap <NUM>, the leaflets <NUM> may be attached to the cuff <NUM> in accordance with the attachment pattern shown in <FIG>. For the purpose of clarity, the leaflet-cuff attachment pattern will be described with reference to <FIG> without showing a belly flap. It will be understood, however, that a belly flap as described above and shown in <FIG> may be disposed either on the inner or luminal side of the leaflet <NUM> or between the leaflet and the cuff <NUM>.

The prosthetic heart valve <NUM> of <FIG> includes a stent or frame <NUM> having an annulus section <NUM> and an aortic section (not shown). Each of the annulus section <NUM> and the aortic section of the stent <NUM> includes a plurality of cells <NUM> connected to one another around the circumference of the stent. The annulus section <NUM> and the aortic section of the stent <NUM> may include one or more annular rows of cells <NUM> connected to one another. For instance, the annulus section <NUM> may have two annular rows of cells <NUM>. When the prosthetic heart valve <NUM> is in the expanded condition, each cell <NUM> may be substantially diamond shaped. Regardless of its shape, each cell <NUM> is formed by a plurality of struts <NUM>. For example, a cell <NUM> may be formed by four struts <NUM>.

The stent <NUM> may include commissure features <NUM> connecting at least two cells <NUM> in the longitudinal direction of the stent. The commissure features <NUM> may include eyelets for facilitating the suturing of a valve assembly <NUM> to the stent <NUM>.

A cuff <NUM> may be disposed on the luminal surface of annulus section <NUM>, on the abluminal surface of the annulus section, or on both surfaces, and the cuff may cover all or part of either or both of the luminal and abluminal surfaces of the annulus section. <FIG> shows cuff <NUM> disposed on the luminal surface of annulus section <NUM> so as to cover part of the annulus section while leaving another part thereof uncovered. In particular, the cuff <NUM> covers substantially all of the annulus section <NUM> between the proximal edge of stent <NUM> and the commissure features <NUM>, but a much lesser area of the annulus section between the commissure features. The valve assembly <NUM> may further include a plurality of leaflets <NUM> which collectively function as a one-way valve.

As shown in <FIG>, struts 314a, 314b, and 314c may be connected to one another in substantially end-to-end fashion diagonally along three cells <NUM>, beginning with an end of the strut 314a connected to a commissure feature 316a and ending with an end of strut 314c connected to an end of strut 314d. Struts 314c and 314d are part of the same cell 312a. Struts 314d, 314e, and 314f may be connected to one another in substantially end-to-end fashion diagonally along three cells <NUM>, beginning with an end of the strut 314f connected to a commissure feature 316b and ending with the connection between an end of strut 314d and an end of strut 314c. For the sake of completeness, cell 312a includes strut 314c connected to strut 314d at the bottom of the cell and struts <NUM> and <NUM> connected to one another at the top of the cell, as well as to struts 314d and 314c, respectively.

In addition to being connected to one another around the circumference of stent <NUM>, cells <NUM> may be connected to one another in the longitudinal direction of the stent. Two adjacent struts, for example struts 314e and <NUM>, merge near the bottom of the cell before splitting off into two different struts. The meeting point where two struts <NUM> merge or where one strut splits into two components is defined as an ancon <NUM>. The ancons <NUM> in two longitudinally adjacent rows of cells <NUM> may be joined by runners r.

The plurality of leaflets <NUM> may be attached directly to the cuff <NUM> near struts 314a, 314b, 314e, and 314f, such as by suturing. As shown in <FIG>, the leaflets <NUM> may be attached to cuff <NUM> just proximally of the aforementioned struts <NUM> along an attachment line R. Specifically, a distance y may be maintained between the attachment line R and the struts <NUM>. This distance may be greater than, less than or equal to <NUM>, and may vary as necessary. By attaching the leaflets <NUM> to the cuff <NUM> in a pattern that follows the curvature of some of the struts <NUM>, stress on the cuff <NUM> may be reduced while maintaining a degree of flexibility.

As described above, the attachment line R includes an initial descent from just proximal of commissure feature 316a and continues proximally of struts 314a and 314b while substantially maintaining a distance y from the struts. At the proximal end of strut 314b, the attachment line R begins to flatten out, passing through cell 312a, and then ascends proximally of struts 314e and 314f, maintaining substantially the same or a similar distance y from the struts, until it reaches a point just proximal of commissure feature 316b. Between the descending seam and the ascending seam, the attachment line may cross a pair of runners r1 and r2 and form a vertex therebetween. In at least some other examples, attachment line R may pass above or below at least one of the runners r1 and r2.

<FIG> shows runners r1 and r2 in more detail. As described above, the attachment line R generally descends from a point just proximal of commissure feature <NUM>, travels proximally of struts 314a and 314b, crosses runner r1, changes direction and crosses runner r2, and then ascends proximally of struts 314e and 314f until it reaches a point just proximal of commissure feature 316b.

The foregoing discussion describes the general pattern by which leaflets <NUM> may be attached directly to cuff <NUM>. Having generally described the attachment pattern, the following description provides one exemplary method of suturing the leaflets <NUM> to the cuff <NUM>. As will be understood by those of ordinary skill in the art, the description below is for one of many possible methods, and the distances, configurations and arrangements described are merely exemplary and not limiting. For example, instead of using a single suture around the perimeter of the valve assembly, leaflets <NUM> may be sutured to the cuff <NUM> using a plurality of sutures, staples, bioglue or any other suitable method of attachment.

Initially, the leaflets <NUM> are aligned with the cuff <NUM> and struts <NUM> at the desired locations, typically in the annulus section <NUM>. The ends of the distal free edge of each leaflet <NUM> are then sutured to both the cuff <NUM> and the stent <NUM> through the eyelets of an adjacent pair of commissure features <NUM>. The belly of the leaflets <NUM> may then be sutured to the cuff <NUM> around the circumference of the heart valve <NUM> proximally of the commissure features <NUM>.

With reference to <FIG>, a first leaflet <NUM> may be sutured to the cuff <NUM> by first passing a suture from the abluminal side of the cuff <NUM> to the luminal side of the cuff about <NUM> to about <NUM> proximally of a first commissure feature 316a. This location will be referred to as the origination stitch. A suture tail segment may be maintained at the origination stitch in order to tie to the end of the pattern after stitching around the circumference of the cuff <NUM> has been completed. The leaflet <NUM> may then be stitched to the cuff <NUM> using a series of whip stitches. In at least some other examples, a running, or reverse-running stitch may be used instead of a whip stitch. Stitches from the abluminal side to the luminal side of the heart valve <NUM> pass through the cuff <NUM> only. Stitches from the luminal side to the abluminal side of the heart valve <NUM> pass through both layers of the leaflet <NUM> (e.g., the leaflet as well as the folded belly flap <NUM>) and the cuff <NUM>. Thus, with each whip stitch the suture is passed from the abluminal side to the luminal side of the heart valve <NUM> through the cuff <NUM> only and then through both layers of the leaflet <NUM> and the cuff <NUM> from the luminal side of the valve to the abluminal side thereof.

The stitch spacing and bite size may vary. In at least some examples, the stitch spacing and bite size may be from about <NUM> to about <NUM>, and preferably is about <NUM>. Stitches may be approximately perpendicular to the leaflet edge when viewed from the side of the valve <NUM>. Beginning just proximally of commissure feature 316a, the sutures may travel approximately at a distance y proximally of struts 314a and 314b, across a first runner r1, form a vertex, across a second runner r2, and approximately at a distance y proximally of struts 314e and 314f until reaching a point just proximal of commissure feature 316b. The sutures may begin at a point A about <NUM> to about <NUM> proximal of commissure feature 316a, and may end at a point B about <NUM> to about <NUM> proximal of commissure feature 316b.

Thus, between the first commissure feature 316a and the second commissure feature 316b, a substantially symmetrical parabola is formed by the suture line R. This parabolic pattern may be repeated between commissure features 316b and 316c and between commissure features 316c and 316a around the circumference of the cuff <NUM>, ending at or near point A where the suture line R began. Upon returning to point A, the concluding tail of the suture line R may be tied to the origination stitch using a single double knot or any other suitable knot.

<FIG> show a comparison between a heart valve <NUM> according to one example of the present invention and a conventional heart valve <NUM>'. As can be seen, the heart valve <NUM> according to the present invention includes an enlarged cuff <NUM> that overlaps with a portion of the leaflets <NUM>. In contrast, the heart valve <NUM>' includes no such overlap between the leaflets <NUM>' and the cuff <NUM>'. Rather, the leaflets <NUM>' and cuff <NUM>' are attached to one another in an edge-to-edge fashion. The leaflet-cuff overlap provided by the heart valve <NUM> of the present invention forms a pocket P and allows for the suture pattern discussed above. Pocket P formed by the leaflet-cuff overlap minimizes perivalvular leakage and acts as a tissue buffer for improved durability. Compared to conventional devices, this configuration also provides a larger buffer against fretting corrosion. Thus, by providing an enlarged cuff, the stress on the cuff may be decreased, the durability of the cuff increased and the flexibility of the heart valve increased to allow for applications such as partial deployment of the heart valve, for example, for testing.

In this manner, by attaching the leaflets <NUM> to the cuff <NUM>, a host of benefits as enumerated above, as well as others, may be achieved. Moreover, the description above provides one method by which stress on the cuff can be reduced. Namely, by suturing the leaflets to the cuff, maintaining the spacing between the suture line and the struts described above, and passing the sutures across the runners, the load on the cuff can be partially redistributed to the struts to prevent possible wear and/or failure. Thus, the foregoing example describes one method for reducing stress on the cuff at critical junctions. This method provides a solution by suturing the leaflets to the cuff without providing a thicker cuff or using different materials for the cuff.

The above example notwithstanding, it will be understood that the leaflets need not be coupled only (except for the commissure features) to the cuff. In other examples, not falling under the scope of the claims, instead of suturing the leaflets to only the cuff, selected regions of each leaflet, or the proximal edge thereof, may be attached to an underwire disposed on or coupled to the cuff to relieve additional stress from the cuff. These examples will be described in more detail with reference to <FIG>.

<FIG> is a partial side view of a prosthetic heart valve <NUM> having a stent <NUM> and a valve assembly <NUM> disposed in the annulus section <NUM> of the stent. Within the heart valve <NUM>, leaflets <NUM> are attached to cuff <NUM> via sutures. <FIG> shows a potential leaflet-cuff attachment load distribution in the valve assembly. When leaflets <NUM> coapt to form a closed configuration, load is transferred from the leaflet structure to the attachment points along the leaflet belly contour. As described in the above examples, these attachment points coincide with attachment line R. The load distribution diagram shows that high point loads are generated at individual sutures at certain regions L along attachment line R. If the point loads at regions L are sufficiently high, they will pull the suture through the material of the cuff <NUM>. Repetitive wear may pull the suture through the material of cuff <NUM>. Thus, regions L may be prone to failure. This failure may occur by tearing of the cuff <NUM>, the leaflet <NUM>, the sutures attaching the cuff <NUM> to the leaflet <NUM> or any combination thereof.

A suture underwire may be attached to the prosthetic heart valve externally of the cuff to redistribute the load at the points at which the leaflets attach to the cuff, reducing the risk of valve structural damage due to a break in the joint/subassembly formed between the cuff and the leaflet attachment line R. Without being bound to any particular theory, it is believed that the underwire may improve cuff durability, improve valve function, reduce perivalvular leakage due to cuff billowing, achieve an optimal leaflet contour and aid in reducing the implant catheter profile.

<FIG> is a highly schematic view of an underwire <NUM> secured to a cuff <NUM>. The underwire <NUM> may be formed of a suture, wire, fabric, polymers, reinforced polymers, a metal such as nitinol, a biomaterial such as pericardial tissue, stainless steel or the like, or any combination thereof, such as a braided wire or metal-suture combination. In some examples, underwire <NUM> may be formed of an ultra-high-molecular-weight polyethylene, such as FORCE FIBER®. The underwire <NUM> may also be formed as a solid rod, a tube or a wire to provide support at certain portions of the cuff <NUM>. In one specific example, the underwire <NUM> may be formed of a nitinol wire that is heat-set to the counter of the cuff <NUM>. As seen in the schematic view of <FIG>, the underwire <NUM> may be attached to the cuff in a parabolic pattern complementing attachment line R. The attachment patterns and configurations of underwire <NUM> will be discussed in more detail below. It is sufficient from this diagram and from the highly schematic diagram of <FIG> to appreciate that the underwire <NUM> will assist in supporting the suturing between the cuff <NUM> and the leaflets <NUM> by providing a reinforcement to redistribute the load between the leaflets and the cuff.

<FIG>, <FIG> describe several patterns for attaching the underwire to the cuff. Though these specific attachment patterns are described herein, it will be understood that any of the patterns described above with reference to attachment line R of <FIG> may be used for attaching the underwire to the cuff. The attachment line may be sutured around or through the underwire to provide additional support. Moreover, it will be understood that the underwire may be attached to the cuff prior to suturing the leaflets to the cuff. For example, the underwire may be attached to the cuff before attaching the cuff to the stent or after attaching the cuff to the stent. Additionally, the underwire may be attached to the cuff at the same time that the leaflets are sutured to the cuff.

In a first example, shown in <FIG>, a prosthetic heart valve <NUM> includes a stent <NUM> and a valve assembly <NUM> disposed in the annulus section <NUM> of the stent. A cuff <NUM> is attached to the stent <NUM> on the luminal side of annulus section <NUM>. Stent <NUM> includes a plurality of struts <NUM> connected to one another to define open cells <NUM>. Struts 814a, 814b, and 814c may be connected to one another in substantially end-to-end fashion diagonally along three cells <NUM>, beginning with an end of the strut 814a connected to a commissure feature 816a and ending with an end of strut 814c connected to an end of strut 814d. Struts 814c and 814d are part of the same cell 812a. For the sake of completeness, cell 812a includes strut 814c connected to strut 814d at the bottom of the cell and struts <NUM> and <NUM> connected to one another at the top of the cell, as well as to struts 814d and 814c, respectively.

Underwire <NUM> may form a pattern around the circumference of cuff <NUM>. As with the attachment line R described above, the pattern of underwire <NUM> may likewise include an initial descent from just proximal of commissure feature 816a and may continue proximally of struts 814a and 814b while substantially maintaining a distance y from the struts. At the proximal end of strut 814b, the pattern of underwire <NUM> begins to flatten out, passing through cell 812a, and then ascends proximally of the next set of struts (not shown in <FIG>), until it reaches a point just proximal of the next commissure feature. It should be noted that the underwire <NUM> in <FIG> is attached to the cuff <NUM> and is disposed between the cuff and the stent <NUM>. With this arrangement, loads from the underwire <NUM> are distributed directly to the cuff <NUM> only and not to the struts <NUM>. Additionally, the pattern of underwire <NUM> in the example of <FIG> begins and ends at points proximal of the commissure features <NUM> as discussed.

<FIG> is a side view of a second example of the attachment of an underwire <NUM> to a cuff <NUM>. The prosthetic heart valve <NUM> is similar to the prosthetic heart valve <NUM> described above, and therefore like elements are identified by like reference numerals that begin with the numeral "<NUM>", instead of the numeral "<NUM>". The manner of attachment for underwire <NUM> is similar to the manner of attachment for underwire <NUM>, with two exceptions. First, underwire <NUM> is attached directly to commissure features <NUM> instead of ending at points proximal of the commissure features. In addition, the underwire <NUM> is disposed outwardly of stent <NUM> as shown in the enlarged view of <FIG>. That is, stent <NUM> is disposed between cuff <NUM> and underwire <NUM>. By attaching underwire <NUM> to the commissure features <NUM> and/or by passing underwire <NUM> outwardly of stent <NUM>, loads may be redistributed from the underwire to the stent struts <NUM>.

It should be understood that any combination of these arrangements may be utilized to attach the underwire <NUM> to the cuff <NUM>. For example, underwire <NUM> may be arranged between cuff <NUM> and stent <NUM> as described in <FIG>, but also may attach to the commissure features <NUM> as described in <FIG>. Alternatively, underwire <NUM> may be arranged outwardly of stent <NUM> at select points only or may be attached to select commissure features or no commissure features. In this manner, the load may be distributed from the underwire to the cuff and/or the stent as desired.

Having described the manner of attaching the underwire to the cuff and stent, some possible arrangements for attaching the leaflets to the cuff and underwire will now be described. Several alternatives for such attachment are shown in <FIG>.

<FIG> is a highly schematic cross-sectional view of a portion of a collapsible prosthetic heart valve <NUM>. Heart valve <NUM> has leaflets <NUM> sutured to both an underwire <NUM> and a cuff <NUM>. Each leaflet <NUM> may be folded upon itself at its proximal end to form a belly flap <NUM> for attaching the leaflet <NUM> to the cuff <NUM>. The belly flap <NUM> may take any of the configurations or arrangements discussed above with reference to <FIG> or may not include a fold at all. The structure of heart valve <NUM> as described in connection with <FIG> may be the same for <FIG>.

The manner in which leaflets <NUM> are attached to cuff <NUM> and underwire <NUM>, as in <FIG>, will be referred to as the "wrapped" configuration. In this wrapped configuration, leaflet <NUM> is folded upon itself to form belly flap <NUM>. A suture T begins from the interior of valve <NUM> and passes through the leaflet <NUM>, the leaflet belly flap <NUM>, and the cuff <NUM>. The suture T then wraps around underwire <NUM> and is passed back toward the interior of the valve through the cuff <NUM> and under the folded edge of leaflet <NUM>, creating a whip stitch. This stitch pattern may be repeated around the entire circumference of valve <NUM> to secure each of leaflets <NUM> and underwire <NUM> to cuff <NUM>.

A second configuration, shown in <FIG>, will be referred to as the "pierced" configuration. In the pierced configuration, the suture T begins at the interior of valve <NUM> and is passed through the leaflet <NUM>, the belly flap <NUM> and the cuff <NUM>. Instead of wrapping around underwire <NUM>, the suture is pierced through underwire <NUM> and passed back toward the interior of the valve through the cuff <NUM> and under the folded edge of leaflet <NUM>. Obviously, in this example the underwire <NUM> must be formed of a material capable of receiving the suture T therethrough. This stitch pattern may be repeated around the entire circumference of valve <NUM> to secure each of leaflets <NUM> and underwire <NUM> to cuff <NUM>.

In a third configuration, the underwire <NUM> is cinched as shown in <FIG>. The "cinched" configuration may begin in a manner similar to the wrapped configuration of <FIG>, with suture T passing from the interior of the valve <NUM> through leaflet <NUM>, belly flap <NUM> and cuff <NUM>. Suture T may then be wrapped in a full loop around the underwire <NUM> and then passed back to the interior of the valve through cuff <NUM> and under the folded edge of leaflet <NUM>. It will be understood that this cinched configuration is not limited to a single loop around underwire <NUM>, and that suture T may wrap around the underwire <NUM> any number of revolutions as desired before passing back to the interior of the valve.

In another configuration, shown in <FIG>, leaflet <NUM> is folded over itself to form belly flap <NUM> and a reverse-running stitch B holds belly flap <NUM> to leaflet <NUM> to create a thickened portion, which will then be coupled to cuff <NUM>. Heart valve <NUM> has leaflets <NUM> sutured to both an underwire <NUM> and a cuff <NUM> as shown in <FIG>. Specifically, a suture T passes through reverse-running stitch B, leaflet <NUM>, leaflet belly flap <NUM>, the other side of revere-running stitch B and cuff <NUM>. The suture T then wraps around underwire <NUM> and is passed back toward the interior of the valve through the cuff <NUM> and under the folded edge of leaflet <NUM>, creating a whip stitch. This stitch pattern may be repeated around the entire circumference of valve <NUM> to secure each of leaflets <NUM> and underwire <NUM> to cuff <NUM>. Folding leaflet <NUM> over itself to create a belly flap and using a reverse-running stitch B to secure the two together produces a thickened portion that provides enhanced structural integrity for attaching the leaflet to cuff <NUM> and underwire <NUM>.

<FIG> are highly schematic cross-sectional views of various configurations for attaching underwire <NUM> to cuff <NUM>. As will be appreciated from these figures, suture T may pass through or around any combination of the reverse-running stitch B, leaflet <NUM>, belly flap <NUM>, cuff <NUM>, and underwire <NUM>. In addition to these configurations, underwire <NUM> may be moved to a different location, or multiple underwires may be utilized. For example, a second underwire <NUM> may be disposed between leaflet <NUM> and belly flap <NUM> to form the thickened portion in addition to underwire <NUM> disposed outside cuff <NUM>. Underwire <NUM> could also be disposed inside cuff <NUM> (e.g., between cuff <NUM> and belly flap <NUM>) or at any other suitable position so long as it helps redistribute load over the cuff and helps prevent tearing of the cuff.

In other variations, underwire <NUM> may be disposed on the outside of the stent struts in certain portions and on the inside of the stent struts in other portions. Underwire <NUM> may also be weaved in and out of cuff <NUM>, and may be attached to the commissure features to provide additional support. Additionally, underwire <NUM> need not be continuous and may be formed of discrete portions disposed around the circumference of the heart valve.

Though the previous configurations have shown a leaflet <NUM> folded over toward the cuff <NUM> to form a belly flap <NUM>, it will be appreciated that the cuff-leaflet assembly, also referred to as a belly attachment contour, is not limited to this configuration. In other examples, the cuff-leaflet assembly may include a leaflet that is folded away from cuff <NUM> to form a belly flap <NUM> on the side of the leaflet <NUM> opposite the cuff. Additionally, leaflet <NUM> of the cuff-leaflet assembly need not form a two-layered belly flap <NUM> at all but may lay flat against cuff <NUM>. It is also contemplated that cuff <NUM> itself may be folded over and that multiple reverse-running stitches may be utilized instead of a single stitch as described above.

As shown in <FIG>, and according to the invention, leaflet <NUM> is folded along only a part of its belly contour. Leaflet <NUM> extends between proximal end <NUM> and distal end <NUM> and includes a belly <NUM> having a free edge <NUM> stretching between attachment regions <NUM>, which couple to the commissure features of a stent. A substantially parabolic belly contour <NUM> is formed between attachment regions <NUM> on the edge of leaflet <NUM> opposite free edge <NUM>. Portions of belly contour <NUM> are folded over to form two-layered folded portions <NUM>. Folded portions <NUM> may be formed with any length f1. In one example, folded portions <NUM> each include about <NUM>/<NUM> to about <NUM>/<NUM> of the length of belly contour <NUM>. In some examples, the length t1 of each folded portion <NUM> is between about <NUM> and about <NUM>, and may be about <NUM>. Folded portions <NUM> may include the end of belly contour <NUM> that are closest to attachment regions <NUM>. Thus, the portion of belly contour <NUM> between folded portions <NUM> may remain substantially flat. By creating an unfolded region spaced from the end of belly contour <NUM>, the bulk of the leaflet may be decreased. To reinforce the belly <NUM> of leaflet <NUM>, which will be attached to a cuff, reverse-running stitch B2 may be formed a distance f2 from belly contour <NUM> and may follow the curvature of the belly contour. As stitch B2 extends through folded portions <NUM> it may secure together the two layers forming folded portions <NUM>. Reverse-running stitch B2 may terminate prior to reaching free edge <NUM> so as not to affect the coaptation of free edge <NUM> with the free edges of the other leaflets, which collectively form the valve assembly. Thus, reverse-running stitch B2 may be spaced from free edge <NUM> by a distance f3. In at least some examples, distance f3 may be between about <NUM> and about <NUM>.

A leaflet having an unfolded belly such as that shown in <FIG> may be coupled to a cuff in a variety of configurations. <FIG> are highly schematic cross-sectional views of some permutations for attaching an underwire <NUM> to a cuff <NUM> having an unfolded belly. As will be appreciated from these figures, sutures T2A-H may pass through or around any combination of reverse-running stitches B2, leaflet <NUM>, underwire <NUM>, and cuff <NUM>.

In <FIG>, suture T2A passes, through inner reverse-running stitch B2I, leaflet <NUM>, outer reverse-running stitch B2O and cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time and under the edge of leaflet <NUM>. Thus, in this configuration, suture T2A passes through both inner reverse-running stitch B2I and outer reverse-running stitch B2O and wraps around underwire <NUM>.

In <FIG>, suture T2B passes, through inner reverse-running stitch B2I and leaflet <NUM>, above outer reverse-running stitch B2O, and through cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time and under the edge of leaflet <NUM>. Thus, in this configuration, suture T2B passes through only inner reverse-running stitch B2I and wraps around both outer reverse-running stitch B2O and underwire <NUM>.

<FIG> show a configuration similar to that of <FIG> except that suture T2C passes under outer reverse-running stitch B2O instead of above it. Thus, in this configuration, suture T2C passes through only inner reverse-running stitch B2I and wraps around only underwire <NUM>.

In <FIG>, suture T2D first passes inwardly through leaflet <NUM>, around inner reverse-running stitch B2I and outwardly through leaflet <NUM>, under outer reverse-running stitch B2O and through cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. Thus, in this configuration, suture T2D does not pass through any reverse-running stitches, wraps around only inner reverse-running stitch B2I and underwire <NUM>, and passes through leaflet <NUM> twice.

In <FIG>, suture T2E passes inwardly through leaflet <NUM>, around inner reverse-running stitch B2I and outwardly through leaflet <NUM>, through outer reverse-running stitch B2O and cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. Thus, in this configuration, suture T2E wraps around both inner reverse-running stitch B2I and underwire <NUM> and passes through outer reverse-running stitch B2O.

In <FIG>, suture T2F passes inwardly through leaflet <NUM>, above inner reverse-running stitch B2I outwardly through leaflet <NUM>, above outer reverse-running stitch B2O and through cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. Thus, in this configuration, suture T2F wraps around all of inner reverse-running stitch B2I, outer reverse-running stitch B2O and underwire <NUM>.

In <FIG>, suture T2G passes inwardly through leaflet <NUM>, through inner reverse-running stitch B2I, outwardly through leaflet <NUM>, above outer reverse-running stitch B2O and through cuff <NUM>, and finally wraps around underwire <NUM> passing through cuff <NUM> a second time. Thus, in this configuration, suture T2G passes through inner reverse-running stitch B2I, and wraps around both outer reverse-running stitch B2O and underwire <NUM>.

In <FIG>, suture T2H passes inwardly through leaflet <NUM>, through inner reverse-running stitch B2I, outwardly through leaflet <NUM>, through outer reverse-running stitch B2O, cuff <NUM>, and underwire <NUM>, and returns by passing through cuff <NUM> a second time. Thus, in this configuration, suture T2H passes through all of inner reverse-running stitch B2I, outer reverse-running stitch B2O and underwire <NUM>, as well as twice through each of cuff <NUM> and leaflet <NUM>.

In <FIG>, suture T2I passes inwardly through leaflet <NUM>, under inner reverse-running stitch B2I, outwardly through leaflet <NUM>, under outer reverse-running stitch B2O and through cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. In this configuration, suture T2I wraps around only underwire <NUM>.

In <FIG>, suture T2J passes inwardly through leaflet <NUM>, under inner reverse-running stitch B2I, outwardly through leaflet <NUM>, through outer reverse-running stitch B2O and cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. In this configuration, suture T2J wraps around only underwire <NUM> and passes through outer reverse-running stitch B2O.

In <FIG>, suture T2K passes inwardly through leaflet <NUM>, under inner reverse-running stitch B2I, outwardly through leaflet <NUM>, over outer reverse-running stitch B2O and through cuff <NUM>, and finally wraps around underwire <NUM> before passing through cuff <NUM> a second time. In this configuration, suture T2K wraps around underwire <NUM> and outer reverse-running stitch B2O.

In addition to these configurations, underwire <NUM> may be moved to a different location, or multiple underwires may be utilized. Moreover, multiple sutures T2 may be used to couple any combination of cuff <NUM>, leaflet <NUM>, reverse-running stitches B2 and underwire <NUM> and may be passed through or around any combination of these elements. <FIG> shows another example of a leaflet <NUM> that is folded along only a part of its belly contour. Leaflet <NUM> extends between proximal end <NUM> and distal end <NUM> and includes a belly <NUM> having a free edge <NUM> stretching between attachment regions <NUM>, which couple to commissure features as described above. A substantially parabolic belly contour <NUM> is formed between attachment regions <NUM> on the edge of leaflet <NUM> opposite free edge <NUM>. Two portions of belly contour <NUM> are folded over to form two-layered folded portions <NUM>. To reinforce belly <NUM>, which will be attached to a cuff, a reverse-running stitch B3 may be formed with two segments, B3a and B3b that follows the curvature of belly contour <NUM> at a spaced distance therefrom in a manner similar to that described with reference to <FIG>. Reverse-running stitch B3 is formed with a different pattern than that shown in <FIG>. Specifically, the first segment B3a of reverse-running stitch B3 has a recurring, substantially diamond-shaped pattern along the belly contour of the leaflet. The selected pattern affects load transfer properties, ease of assembly, and bulkiness. In this case, the pattern of the first segment B3a of reverse-running stitch B3 may provide a larger area to suture into instead of going through/around a single line of reverse-running stitch.

The first segment B3a of reverse-running stitch B3 may terminate prior to reaching folded portions <NUM>, the layers of which may be secured together by a curved second segment B3b or reverse-running stitch B3. Alternatively, first segment B3a may extend through folded portion <NUM>. Additionally, reverse-running stitch B3 may terminate prior to reaching free edge <NUM> so as not to affect the coaptation of free edge <NUM> with the free edges of the other leaflets, which collectively form the valve assembly.

<FIG> shows another example of a leaflet <NUM> that is folded along only part of its belly contour. Leaflet <NUM> extends between proximal end <NUM> and distal end <NUM> and includes a belly <NUM> having a free edge <NUM> stretching between attachment regions <NUM>, which couple to commissure features as described above. A substantially parabolic belly contour <NUM> is formed between attachment regions <NUM> on the edge of leaflet <NUM> opposite free edge <NUM>. Portions of belly contour <NUM> are folded over to form two-layered folded portions <NUM>. To reinforce belly <NUM>, which will be attached to a cuff, a reverse-running stitch B4 may be formed with two complementary second segments, B4a and B4b that follow the curvature of belly contour <NUM> at a spaced distance therefrom. In this example, segments B4a and B4b of reverse-running stitch B4 are not attached to one another.

First segment B4a may be substantially parabolic and may terminate prior to reaching folded portions <NUM>. Second segment B4b may follow the contour of first segment B4b at a spaced distance therefrom to define a coupling area <NUM> therebetween for suturing leaflet <NUM> to a cuff. Second segment B4b may extend through folded portions <NUM> to secure the two layers of each folded portion together. In either case, reverse-running stitch B4 may terminate prior to reaching free edge <NUM> so as not to affect the coaptation of free edge <NUM> with the free edges of the other leaflets, which collectively form the valve assembly.

<FIG> shows another example that is similar to that of <FIG>, except for the pattern of reverse-running stitch B5. Leaflet <NUM> extends between proximal end <NUM> and distal end <NUM> and includes a belly <NUM> having a free edge <NUM> stretching between attachment regions <NUM>, and a substantially parabolic belly contour <NUM> formed between attachment regions <NUM> on the edge of leaflet <NUM> opposite free edge <NUM>. Reverse-running stitch B5 may be formed with two complementary segments, B5a and B5b that follow the curvature of belly contour <NUM> at a spaced distance therefrom. Segments B5a and B5b of reverse-running stitch B5 are attached to one another by segments B5c, thereby creating a number of coupling rectangles <NUM> for receiving sutures to couple leaflet <NUM> to a cuff.

First segment B5a may be substantially parabolic and may terminate prior to reaching folded portion <NUM>. Second segment B5b may follow the contour of first segment B5b at a spaced distance therefrom, and may extend through folded portions <NUM> to secure the two layers of each folded portion together. Suture <NUM> may couple leaflet <NUM> to a cuff through coupling rectangles <NUM>. Specifically, suture <NUM> may be passed through the perimeter of a coupling rectangle <NUM>. It may be advantageous to pierce the perimeter of coupling rectangle <NUM> without piercing through the interior of coupling rectangle <NUM> more than once and without piercing the belly <NUM> in regions outside of coupling rectangle <NUM>.

<FIG> shows another example that is similar to that of <FIG>, except for the pattern of reverse-running stitch B6. Leaflet <NUM> extends between proximal end <NUM> and distal end <NUM> and includes a belly <NUM> having a free edge <NUM> stretching between attachment regions <NUM>, and a substantially parabolic belly contour <NUM> formed between attachment regions <NUM> on the edge of leaflet <NUM> opposite free edge <NUM>. Reverse-running stitch B6 may be formed with two segments, B6a and B6b that follow the curvature of belly contour <NUM> at a spaced distance therefrom.

First segment B6a of reverse-running stitch B6 may include a recurring triangular pattern for accepting a suture therethrough. Suture <NUM> may couple leaflet <NUM> to a cuff through coupling triangles <NUM>. Specifically, suture <NUM> may be passed through the perimeter of a coupling triangle <NUM>. It may be advantageous to pierce the perimeter of coupling triangle <NUM> without piercing through the interior of coupling triangle <NUM> more than once and without piercing the belly <NUM> in regions outside of coupling triangle <NUM>.

In operation, any of the examples of the prosthetic heart valve described above may be used to replace a native heart valve, such as the aortic valve. The prosthetic heart valve may be delivered to the desired site (e.g., near a native aortic annulus) using any suitable delivery device. During delivery, the prosthetic heart valve is disposed inside the delivery device in the collapsed condition. The delivery device may be introduced into a patient using a transfemoral, transapical, transseptal, transradial, transaortic, transsubclavian or other percutaneous approach. Once the delivery device has reached the target site, the user may deploy the prosthetic heart valve. Upon deployment, the prosthetic heart valve expands into secure engagement within the native aortic annulus. When the prosthetic heart valve has been properly positioned inside the heart, it works as a one-way valve, allowing blood to flow in one direction and preventing blood from flowing in the opposite direction.

Although the invention herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the present invention. For example, in some examples, the underwire may include certain anchoring features, such as barbs for anchoring the heart valve or for valve-in-valve implantation. In at least some other examples, the underwire may include a surface finish or be doped with drugs or other material to ensure tissue ingrowth and sealing. Moreover, while the preceding discussion has provided examples by way of folded leaflets, it will be understood that the leaflet need not be folded and that the heart valve may instead include a belly attachment contour having an unfolded leaflet instead of a folded leaflet.

In some examples, a prosthetic heart valve includes a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of commissure features. The heart valve further includes a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the leaflets having a free edge having a first end and a second end, and a second edge secured to the cuff, the second edge having a first end, a second end, a first folded portion adjacent the first end, a second folded portion adjacent the second end, and an unfolded portion between the first and second folded portions. The first and second folded portions couple the leaflet to ones of the commissure features.

In some examples, a reinforcement may be disposed along the unfolded portion of each of the leaflets. The reinforcement may include a reverse-running stitch. The reverse-running stitch may be formed in a substantially parabolic pattern that follows the curvature of the unfolded portion. The reverse-running stitch may include multiple segments and at least one of the segments extends over one of the first folded portion and the second folded portion. The reverse-running stitch may include a recurring diamond-shaped pattern. The reverse-running stitch may include a recurring rectangular pattern. The reverse-running stitch may include a recurring triangular pattern. The reverse-running stitch may be spaced away from the free edge of the leaflet. The reverse-running stitch may be spaced away from the free edge of the leaflet. The reverse-running stitch may include two complementary parabolic curves defining a coupling region therebetween for receiving sutures. A reinforcing underwire may be coupled to the cuff. The underwire may form a repeating parabolic pattern about the circumference of the cuff.

Claim 1:
A prosthetic heart valve, comprising:
a stent (<NUM>) having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of commissure features (<NUM>), wherein the prosthetic heart valve further includes;
a valve assembly (<NUM>) secured to the stent, the valve assembly including a cuff (<NUM>) and a plurality of leaflets (<NUM>), each of the leaflets having a proximal end (<NUM>), a distal end (<NUM>), a belly (<NUM>) having a free edge (<NUM>) and a second edge opposite the free edge, and a belly contour (<NUM>) that is substantially parabolic, the free edge stretching between first and second attachment regions (<NUM>), the first attachment region attached to one of the plurality of commissure features and the second attachment region attached to another of the plurality of commissure features, the second edge secured to the cuff, the second edge having a first end, a second end, folded portions (<NUM>) adjacent the first end and the second end, and an unfolded portion between the folded portions, the folded portions coupling the leaflet to ones of the commissure features, the belly contour formed between the first and second attachment regions on the second edge; and
a reinforcement consisting solely of a reverse-running stitch disposed along the unfolded portion and spaced a distance (f2) from the second edge of each of the plurality of leaflets.