Patent Description:
The human heart can suffer from various valvular diseases. These valvular diseases can result in significant malfunctioning of the heart and ultimately require replacement of the native valve with an artificial valve. There are a number of known artificial valves and a number of known methods of implanting these artificial valves in humans.

Various surgical techniques may be used to replace or repair a diseased or damaged valve. Due to stenosis and other heart valve diseases, thousands of patients undergo surgery each year wherein the defective native heart valve is replaced by a prosthetic valve. Another less drastic method for treating defective valves is through repair or reconstruction, which is typically used on minimally calcified valves. The problem with surgical therapy is the significant risk it imposes on these chronically ill patients with high morbidity and mortality rates associated with surgical repair.

When the native valve is replaced, surgical implantation of the prosthetic valve typically requires an open-chest surgery during which the heart is stopped and patient placed on cardiopulmonary bypass (a so-called "heart-lung machine"). In one common surgical procedure, the diseased native valve leaflets are excised and a prosthetic valve is sutured to the surrounding tissue at the valve annulus. Because of the trauma associated with the procedure and the attendant duration of extracorporeal blood circulation, some patients do not survive the surgical procedure or die shortly thereafter. It is well known that the risk to the patient increases with the amount of time required on extracorporeal circulation. Due to these risks, a substantial number of patients with defective native valves are deemed inoperable because their condition is too frail to withstand the procedure. By some estimates, more than <NUM>% of the subjects suffering from valve stenosis who are older than <NUM> years cannot be operated on for valve replacement.

Because of the drawbacks associated with conventional open-heart surgery, percutaneous and minimally-invasive surgical approaches are garnering intense attention. In one technique, a prosthetic valve is configured to be implanted in a much less invasive procedure by way of catheterization. For instance, <CIT> and <CIT>, describe collapsible transcatheter heart valves that can be percutaneously introduced in a compressed state on a catheter and expanded in the desired position by balloon inflation or by utilization of a self-expanding frame or stent.

<CIT> discloses a stented valve including a stent structure including a generally tubular body portion that has a first end and a second end. The stented valve further includes a valve structure attached within the generally tubular portion.

An important design parameter of a transcatheter heart valve is the diameter of the folded or crimped profile. The diameter of the crimped profile is important because it directly influences the physician's ability to advance the transcatheter heart valve through the femoral artery or vein. More particularly, a smaller profile allows for treatment of a wider population of patients, with enhanced safety.

The claimed invention is defined in independent claim <NUM> and relates to an implantable prosthetic heart valve that is collapsible to a collapsed configuration and expandable to an expanded configuration. Preferred configurations of the claimed invention are defined in dependent claims <NUM> to <NUM>. Certain aspects and/or particularly preferred configurations of the claimed invention are discussed hereafter for example in conjunction with <FIG>. Also described herein are related aspects, examples, embodiments and arrangements useful for understanding the claimed invention.

The present disclosure is directed toward methods and apparatuses relating to prosthetic valves, such as heart valves, delivery apparatuses, and assemblies of heart valves mounted on delivery apparatuses.

An exemplary embodiment of an assembly for implanting a prosthetic heart valve in a patient's body comprises a delivery apparatus comprising an elongated shaft and a radially expandable prosthetic heart valve mounted on the shaft in a radially collapsed configuration for delivery into the body. The prosthetic heart valve comprises an annular frame having an inflow end portion and an outflow end portion, and a leaflet structure positioned within the frame. The outer diameter of the inflow end portion of the frame is smaller than the outer diameter of the outflow end portion of the frame. The reduced diameter of the inflow end can be due to a reduce amount of materials positioned within the inflow end portion of the frame. The reduced diameter at the inflow end portion can make room for an outer skirt positioned around the inflow end portion.

In some embodiments, the heart valve can further comprise an outer skirt positioned around an outer surface of the inflow end portion of the frame such that an outer diameter of an inflow end portion of the prosthetic valve, inclusive of the outer skirt, is still less than or equal to an outer diameter of an outflow end portion of the prosthetic valve.

In some embodiments, the leaflet structure can comprise a plurality of leaflets that each comprises opposing side tabs on opposite sides of the leaflet. The side tabs can be secured to the outflow end portion of the frame. Each leaflet can further comprise a free outflow edge portion extending between the side tabs adjacent to the outflow end of the frame and an inflow edge portion extending between the side tabs adjacent to the inflow end of the frame. The inflow edge portion can comprise opposing axial edge portions that extend from the side tabs toward the inflow end in a generally axial direction and an intermediate edge portion that extends between the axial edge portions. The intermediate edge portion can comprise a curved apex portion adjacent to the inflow end of the frame and a pair of oblique portions that extend between the axial edge portions and the apex portion. The oblique portions can have a greater radius of curvature than the apex portion, forming a generally V-shaped leaflet.

In some embodiments, the frame comprises a plurality of angularly spaced commissure windows each comprising an enclosed opening between first and second axially oriented side struts. In these embodiments, the leaflet structure comprises a plurality of leaflets each comprising two opposing side tabs, each side tab being paired with an adjacent side tab of an adjacent leaflet to form commissures of the leaflet structure. Each commissure extends radially outwardly through a corresponding commissure window of the frame to a location outside of the frame and is sutured to the side struts of the commissure window. In some of these embodiments, the commissure windows of the frame are depressed radially inwardly relative to the portions of the frame extending between adjacent commissure windows when the prosthetic valve is in the collapsed configuration on the shaft.

The frame comprises an inflow row of openings at the inflow end portion of the frame, an outflow row of openings at the outflow end portion of the frame, and at least one intermediate row of openings between the inflow row of openings and outflow row of openings. The openings of the inflow row of openings are larger than the openings of the at least one intermediate row of openings.

In some embodiments, portions of the leaflet structure protrude through openings in the frame while in the collapsed configuration on the shaft.

In some embodiments, the inflow end portion of the frame comprises a frame thickness that is less than a frame thickness of an intermediate portion of the frame between the inflow end portion and the outflow end portion.

Embodiments disclosed here can comprise an implantable prosthetic valve that is radially collapsible to a collapsed configuration and radially expandable to an expanded configuration. Such prosthetic valves can comprise an annular frame, a leaflet structure positioned within the frame, and an annular outer skirt positioned around an outer surface of the frame. The outer skirt can comprise an inflow edge secured to the frame at a first location, an outflow edge secured to the frame at a second location, and an intermediate portion between the inflow edge and the outflow edge. When the valve is in the expanded configuration, the intermediate portion of the outer skirt comprises slack in the axial direction between the inflow edge of the outer skirt and the outflow edge of the outer skirt, and when the valve is collapsed to the collapsed configuration, the axial distance between the inflow edge of the outer skirt and the outflow edge of the outer skirt increases, reducing the slack in the outer skirt in the axial direction.

In some of these embodiments, the outer skirt is not stretched in the axial direction when the valve is radially collapsed to the collapsed configuration and slack is removed from the intermediate portion of the outer skirt.

Some embodiments of an implantable prosthetic valve comprise an annular frame comprising a plurality of leaflet attachment portions, and a leaflet structure positioned within the frame and secured to the leaflet attachment portions of the frame. The leaflet structure comprises a plurality of leaflets, each leaflet comprising a body portion, two opposing primary side tabs extending from opposite sides of the body portion, and two opposing secondary tabs extending from the body adjacent to the primary side tabs. The secondary tabs are folded about a radially extending crease such that a first portion of the secondary tabs lies flat against the body portion of the respective leaflet, and the secondary tabs are folded about an axially extending crease such that a second portion of the secondary tabs extends in a different plane than the first portion. The second portion of each secondary tab is sutured to a respective primary tab and the secondary tabs are positioned inside of the frame.

In some of these embodiments, the first portion of each the secondary tab pivots about the axially extending crease and lays flat against the second portion of the secondary tab when the valve is collapsed to a radially collapsed configuration. The first portion of each secondary tab comprises an inner edge spaced radially from an inner surface of the frame, and the body portion of the leaflet articulates about the inner edges of the two secondary tabs of the leaflet in response to blood flowing through the valve when the valve is in operation within a patient's body.

Some embodiments disclosed herein comprise an implantable prosthetic valve that is radially collapsible to a collapsed configuration and radially expandable to an expanded configuration. The prosthetic valve comprises an annular frame having an inflow end portion and an outflow end portion, a leaflet structure positioned within the frame, and an annular inner skirt positioned within the frame. The inner skirt is secured to the inside of the frame and the inner skirt comprises a weave of a first set of strands with a second set of strands, both the first and second sets of strands being non-parallel with the axial direction of the valve. When the valve is collapsed from the expanded configuration to the collapsed configuration, the axial length of the frame increases and the both the first and second sets of strands rotate toward the axial direction of the valve, allowing the inner skirt to elongate in the axial direction along with the frame.

In some of these embodiments, the first set of strands are substantially perpendicular to the second set of strands when the valve is in the expanded configuration. In some embodiments, the first set of strands forms a first angle with the axial direction of the valve and the second set of strands forms a second angle with the axial direction of the valve, the first and second angles being substantially equal. In some of these embodiments, the first and second sets of strands comprise <NUM>-denier yarn.

Some embodiments of an implantable prosthetic valve comprise a radially collapsible and expandable annular frame comprising a plurality of angularly spaced commissure windows each comprising an enclosed opening between first and second axially oriented side struts. The valve also comprises a leaflet structure positioned within the frame and comprising a plurality of leaflets each comprising two opposing side tabs. Each side tab is paired with an adjacent side tab of an adjacent leaflet to form commissures of the leaflet structure. Each pair of side tabs extends radially outwardly through a corresponding commissure window to a location outside of the frame, the portions of the tabs located outside of the frame extending circumferentially away from one another and along an exterior surface of the side struts. The valve further comprises a plurality of wedges, each wedge being positioned between the side struts of a commissure window and separating the pair of side tabs extending through the commissure window, the wedge being urged radially inwardly against the side tabs.

The wedges can be elongated in an axial direction and correspond in axial length with an axial length of the side struts of the commissure windows. The wedges can further restrict rotational movement of the pair of side tabs relative to the commissure window. Each wedge can be sutured to a flexible reinforcing sheet that is also sutured to each of the pair of side tabs, and each can be sutured to the pair of side tabs. The wedges can comprise a non-metallic material, such as suture material.

<FIG> show various views of a prosthetic heart valve <NUM>, according to one embodiment. The illustrated valve is adapted to be implanted in the native aortic annulus, although in other embodiments it can be adapted to be implanted in the other native annuluses of the heart. The valve <NUM> can have four main components: a stent, or frame, <NUM>, a valvular structure <NUM>, an inner skirt <NUM>, and an outer skirt <NUM>.

The valvular structure <NUM> can comprise three leaflets <NUM>, collectively forming a leaflet structure, which can be arranged to collapse in a tricuspid arrangement, as best shown in <FIG>. The lower edge of leaflet structure <NUM> desirably has an undulating, curved scalloped shape (suture line <NUM> shown in <FIG> tracks the scalloped shape of the leaflet structure). By forming the leaflets with this scalloped geometry, stresses on the leaflets are reduced, which in turn improves durability of the valve. Moreover, by virtue of the scalloped shape, folds and ripples at the belly of each leaflet (the central region of each leaflet), which can cause early calcification in those areas, can be eliminated or at least minimized. The scalloped geometry also reduces the amount of tissue material used to form leaflet structure, thereby allowing a smaller, more even crimped profile at the inflow end of the valve. The leaflets <NUM> can be formed of pericardial tissue (e.g., bovine pericardial tissue), biocompatible synthetic materials, or various other suitable natural or synthetic materials as known in the art and described in <CIT>.

The bare frame <NUM> is shown in <FIG>. The frame <NUM> can be formed with a plurality of circumferentially spaced slots, or commissure windows, <NUM> (three in the illustrated embodiment) that are adapted to mount the commissures of the valvular structure <NUM> to the frame, as described in greater detail below. The frame <NUM> can be made of any of various suitable plastically-expandable materials (e.g., stainless steel, etc.) or self-expanding materials (e.g., Nitinol) as known in the art. When constructed of a plastically-expandable material, the frame <NUM> (and thus the valve <NUM>) can be crimped to a radially compressed state on a delivery catheter and then expanded inside a patient by an inflatable balloon or equivalent expansion mechanism. When constructed of a self-expandable material, the frame <NUM> (and thus the valve <NUM>) can be crimped to a radially compressed state and restrained in the compressed state by insertion into a sheath or equivalent mechanism of a delivery catheter. Once inside the body, the valve can be advanced from the delivery sheath, which allows the valve to expand to its functional size.

Suitable plastically-expandable materials that can be used to form the frame <NUM> include, without limitation, stainless steel, a nickel based alloy (e.g., a cobalt-chromium or a nickel-cobalt-chromium alloy), polymers, or combinations thereof. In particular embodiments, frame <NUM> is made of a nickel-cobalt-chromium-molybdenum alloy, such as MP35N™ (tradename of SPS Technologies), which is equivalent to UNS R30035 (covered by ASTM F562-<NUM>). MP35N™/UNS R30035 comprises <NUM>% nickel, <NUM>% cobalt, <NUM>% chromium, and <NUM>% molybdenum, by weight. It has been found that the use of MP35N to form frame <NUM> provides superior structural results over stainless steel. In particular, when MP35N is used as the frame material, less material is needed to achieve the same or better performance in radial and crush force resistance, fatigue resistances, and corrosion resistance. Moreover, since less material is required, the crimped profile of the frame can be reduced, thereby providing a lower profile valve assembly for percutaneous delivery to the treatment location in the body.

Referring to <FIG>, the frame <NUM> in the illustrated embodiment comprises a first, lower row I of angled struts <NUM> arranged end-to-end and extending circumferentially at the inflow end of the frame; a second row II of circumferentially extending, angled struts <NUM>; a third row III of circumferentially extending, angled struts <NUM>; a fourth row IV of circumferentially extending, angled struts <NUM>; and a fifth row V of circumferentially extending, angled struts <NUM> at the outflow end of the frame. A plurality of substantially straight axially extending struts <NUM> can be used to interconnect the struts <NUM> of the first row I with the struts <NUM> of the second row II. The fifth row V of angled struts <NUM> are connected to the fourth row IV of angled struts <NUM> by a plurality of axially extending window frame portions <NUM> (which define the commissure windows <NUM>) and a plurality of axially extending struts <NUM>. Each axial strut <NUM> and each frame portion <NUM> extends from a location defined by the convergence of the lower ends of two angled struts <NUM> to another location defined by the convergence of the upper ends of two angled struts <NUM>. <FIG>, <FIG> are enlarged views of the portions of the frame <NUM> identified by letters A, B, C, D and E, respectively, in <FIG>.

Each commissure window frame portion <NUM> mounts a respective commissure of the leaflet structure <NUM>. As can be seen each frame portion <NUM> is secured at its upper and lower ends to the adjacent rows of struts to provide a robust configuration that enhances fatigue resistance under cyclic loading of the valve compared to known cantilevered struts for supporting the commissures of the leaflet structure. This configuration enables a reduction in the frame wall thickness to achieve a smaller crimped diameter of the valve. In particular embodiments, the thickness T of the frame <NUM> (<FIG>) measured between the inner diameter and outer diameter is about <NUM> or less.

The struts and frame portions of the frame collectively define a plurality of open cells of the frame. At the inflow end of the frame <NUM>, struts <NUM>, struts <NUM>, and struts <NUM> define a lower row of cells defining openings <NUM>. The second, third, and fourth rows of struts <NUM>, <NUM>, and <NUM> define two intermediate rows of cells defining openings <NUM>. The fourth and fifth rows of struts <NUM> and <NUM>, along with frame portions <NUM> and struts <NUM>, define an upper row of cells defining openings <NUM>. The openings <NUM> are relatively large and are sized to allow portions of the leaflet structure <NUM> to protrude, or bulge, into and/or through the openings <NUM> when the frame <NUM> is crimped in order to minimize the crimping profile.

As best shown in <FIG>, the lower end of the strut <NUM> is connected to two struts <NUM> at a node or junction <NUM>, and the upper end of the strut <NUM> is connected to two struts <NUM> at a node or junction <NUM>. The strut <NUM> can have a thickness S <NUM> that is less than the thicknesses S2 of the junctions <NUM>, <NUM>. <FIG> shows a portion of the frame <NUM> in a crimped state. The junctions <NUM>, <NUM>, along with junctions <NUM>, prevent full closure of openings <NUM>. <FIG> shows the valve <NUM> crimped on a balloon catheter. As can be seen, the geometry of the struts <NUM>, and junctions <NUM>, <NUM> and <NUM> assists in creating enough space in openings <NUM> in the crimped state to allow portions of the leaflets to protrude (i.e., bulge) outwardly through openings. This allows the valve to be crimped to a relatively smaller diameter than if all of the leaflet material is constrained within the crimped frame.

The frame <NUM> is configured to prevent or at least minimize possible over-expansion of the valve at a predetermined balloon pressure, especially at the outflow end portion of the frame, which supports the leaflet structure <NUM>. In one aspect, the frame is configured to have relatively larger angles 42a, 42b, 42c, 42d, 42e between struts. The larger the angle, the greater the force required to open (expand) the frame. This phenomenon is schematically illustrated in <FIG> shows a strut <NUM> when the frame <NUM> is in its compressed state (e.g., mounted on a balloon). The vertical distance di between the ends of the struts is greatest when the frame is compressed, providing a relatively large moment between forces F<NUM> and F<NUM> acting on the ends of the strut in opposite directions upon application of an opening force from inflation of the balloon (or expansion of another expansion device). When the frame expands radially, the vertical distance between the ends of the strut decreases to a distance d<NUM>, as depicted in <FIG>. As the vertical distance decreases, so does the moment between forces F<NUM> and F<NUM>. Hence, it can be seen that a relatively greater expansion force is required as the vertical distance and the moment between the ends of the strut decreases. Moreover, strain hardening (stiffening) at the ends of the strut increases as the frame expands, which increases the expansion force required to induce further plastic deformation at the ends of the strut. As such, the angles between the struts of the frame can be selected to limit radial expansion of the frame at a given opening pressure (e.g., inflation pressure of the balloon). In particular embodiments, these angles are at least <NUM> degrees or greater when the frame is expanded to its functional size, and even more particularly these angles are at least <NUM> degrees or greater when the frame is expanded to its functional size.

In addition, the inflow and outflow ends of a frame generally tend to over-expand more so than the middle portion of the frame due to the "dog boning" effect of the balloon used to expand the valve. To protect against over-expansion of the leaflet structure <NUM>, the leaflet structure desirably is secured to the frame <NUM> below the upper row of struts <NUM>, as best shown in <FIG>. <FIG> shows a flattened view of the frame <NUM> similar to <FIG>, but showing a line <NUM> superimposed over the frame to indicate the position of the upper edges of the leaflets <NUM>. Thus, in the event that the outflow end of the frame is over-expanded, the leaflet structure is positioned at a level below where over-expansion is likely to occur, thereby protecting the leaflet structure from over-expansion.

In a known valve construction, the leaflets can protrude outwardly beyond the outflow end of the frame when the valve is crimped if the leaflets are mounted too close to the distal end of the frame. If the delivery catheter on which the crimped valve is mounted includes a pushing mechanism or stop member that pushes against or abuts the outflow end of the valve (for example, to maintain the position of the crimped valve on the delivery catheter), the pushing member or stop member can damage the exposed leaflets that extend beyond the outflow end of the frame. Another benefit of mounting the leaflets at a location spaced from the outflow end <NUM> of the frame is that when the valve is crimped on a delivery catheter, as shown in <FIG>, the leaflets <NUM> do not protrude beyond the outflow end <NUM> of the frame in the axial direction. As such, if the delivery catheter includes a pushing mechanism or stop member that pushes against or abuts the outflow end of the valve, the pushing mechanism or stop member can contact the end <NUM> of the frame, and not leaflets <NUM>, so as to avoid damage to the leaflets.

Also, as can be seen in <FIG>, the openings <NUM> of the lowermost row of openings in the frame are relatively larger than the openings <NUM> of the two intermediate rows of openings. As shown in <FIG>, this allows the frame, when crimped, to assume an overall tapered shape that tapers from a maximum diameter D<NUM> at the outflow end of the valve to a minimum diameter D<NUM> at the inflow end of the valve. When crimped, the frame <NUM> has a reduced diameter region extending along a portion of the frame adjacent the inflow end of the frame, indicated by reference number <NUM>, that generally corresponds to the region of the frame covered by the outer skirt <NUM>. The diameter of region <NUM> is reduced compared to the diameter of the upper portion of the frame (which is not covered by the outer skirt) such that the outer skirt <NUM> does not increase the overall crimp profile of the valve. When the valve is deployed, the frame can expand to the cylindrical shape shown in <FIG>. In one example, the frame of a <NUM>-mm valve, when crimped, had a diameter D<NUM> of <NUM> French at the outflow end of the valve and a diameter D<NUM> of <NUM> French at the inflow end of the valve.

<FIG> and <FIG> show an alternative frame <NUM> that can be incorporated in the valve <NUM>. The frame <NUM> comprises multiple rows of circumferentially extending, angled struts <NUM> that are connected to each other at nodes, or connecting portions, <NUM> and <NUM>. The uppermost row of struts <NUM> are connected to an adjacent row of struts by a plurality of axially extending struts <NUM> and commissure window frame portions <NUM>. Each commissure frame portion <NUM> defines a slot, or commissure window, <NUM> for mounting a respective commissure of the valvular structure, as described in greater detail below. In particular embodiments, the thickness T of the frame <NUM> is about <NUM> or less. <FIG> are enlarged views of the portions of the frame <NUM> identified by letters A and B, respectively, in <FIG>.

The main functions of the inner skirt <NUM> are to assist in securing the valvular structure <NUM> to the frame <NUM> and to assist in forming a good seal between the valve and the native annulus by blocking the flow of blood through the open cells of the frame <NUM> below the lower edge of the leaflets. The inner skirt <NUM> desirably comprises a tough, tear resistant material such as polyethylene terephthalate (PET), although various other synthetic or natural materials can be used. The thickness of the skirt desirably is less than <NUM> mil, and desirably less than <NUM> mil, and even more desirably about <NUM> mil. In particular embodiments, the skirt <NUM> can have a variable thickness, for example, the skirt can be thicker at its edges than at its center. In one implementation, the skirt <NUM> can comprise a PET skirt having a thickness of about <NUM> at its edges and about <NUM> at its center. The thinner skirt can provide for better crimping performances while still providing good perivalvular sealing.

The skirt <NUM> can be secured to the inside of frame <NUM> via sutures <NUM>, as shown in <FIG>. Valvular structure <NUM> can be attached to the skirt via one or more thin PET reinforcing strips <NUM> (which collectively can form a sleeve), discussed below, which enables a secure suturing and protects the pericardial tissue of the leaflet structure from tears. Valvular structure <NUM> can be sandwiched between skirt <NUM> and the thin PET strips <NUM> as shown in <FIG>. Sutures <NUM>, which secure the PET strip and the leaflet structure <NUM> to skirt <NUM>, can be any suitable suture, such as an Ethibond suture. Sutures <NUM> desirably track the curvature of the bottom edge of leaflet structure <NUM>, as described in more detail below.

Known fabric skirts comprise a weave of warp and weft fibers that extend perpendicular to each other and with one set of fibers extending perpendicularly to the upper and lower edges of the skirt. When the metal frame, to which the fabric skirt is secured, is radially compressed, the overall axial length of the frame increases. Unfortunately, a fabric skirt, which inherently has limited elasticity, cannot elongate along with the frame and therefore tends to deform the struts of the frame and prevents uniform crimping.

<FIG> shows an example of a crimped valve where the struts have been deformed in several places, as indicated by reference number <NUM>, by a skirt having fibers that extend perpendicular to the upper and lower edges of the skirt. Moreover, the fabric tends to bunch or create bulges of excess material in certain locations, which limits the minimum crimping profile and prevents uniform crimping.

Referring to <FIG>, in contrast to known fabric skirts, the skirt <NUM> desirably is woven from a first set of fibers, or yarns or strands, <NUM> and a second set of fibers, or yarns or strands, <NUM>, both of which are non-perpendicular to the upper edge <NUM> and the lower edge <NUM> of the skirt. In particular embodiments, the first set of fibers <NUM> and the second set of fibers <NUM> extend at angles of about <NUM> degrees relative to the upper and lower edges <NUM>, <NUM>. The skirt <NUM> can be formed by weaving the fibers at <NUM> degree angles relative to the upper and lower edges of the fabric. Alternatively, the skirt can be diagonally cut from a vertically woven fabric (where the fibers extend perpendicular to the edges of the material) such that the fibers extend at <NUM> degree angles relative to the cut upper and lower edges of the skirt. As further shown in <FIG>, the opposing short edges <NUM>, <NUM> of the skirt desirably are non-perpendicular to the upper and lower edges <NUM>, <NUM>. For example, the short edges <NUM>, <NUM> desirably extend at angles of about <NUM> degrees relative to the upper and lower edges and therefore are aligned with the first set of fibers <NUM>. Therefore the overall shape of the skirt is that of a rhomboid.

<FIG> shows the skirt <NUM> after opposing edge portions <NUM>, <NUM> have been sewn together to form the annular shape of the skirt. As shown, the edge portion <NUM> can be placed in an overlapping relationship relative to the opposite edge portion <NUM>, and the two edge portions can be sewn together with a diagonally extending suture line <NUM> that is parallel to edges <NUM>, <NUM>. The upper edge portion of the skirt <NUM> can be formed with a plurality of projections <NUM> that define an undulated shape that generally follows the shape of the fourth row of struts <NUM> immediately adjacent the lower ends of axial struts <NUM>. In this manner, as best shown in <FIG>, the upper edge of skirt <NUM> can be tightly secured to struts <NUM> with sutures <NUM>. Skirt <NUM> can also be formed with slits <NUM> to facilitate attachment of the skirt to the frame. Slits <NUM> are dimensioned so as to allow an upper edge portion of skirt to be partially wrapped around struts <NUM> and reduce stresses in the skirt during the attachment procedure. For example, in the illustrated embodiment, skirt <NUM> is placed on the inside of frame <NUM> and an upper edge portion of the skirt is wrapped around the upper surfaces of struts <NUM> and secured in place with sutures <NUM>. Wrapping the upper edge portion of the skirt around struts <NUM> in this manner provides for a stronger and more durable attachment of the skirt to the frame. The skirt <NUM> can also be secured to the first, second, and third rows of struts <NUM>, <NUM>, and <NUM>, respectively, with sutures <NUM>.

Referring again to <FIG>, due to the orientation of the fibers relative to the upper and lower edges, the skirt can undergo greater elongation in the axial direction (i.e., in a direction from the upper edge <NUM> to the lower edge <NUM>).

Thus, when the metal frame <NUM> is crimped (as shown in <FIG>), the skirt <NUM> can elongate in the axial direction along with the frame and therefore provides a more uniform and predictable crimping profile. Each cell of the metal frame in the illustrated embodiment includes at least four angled struts that rotate towards the axial direction (i.e., the angled struts become more aligned with the length of the frame). The angled struts of each cell function as a mechanism for rotating the fibers of the skirt in the same direction of the struts, allowing the skirt to elongate along the length of the struts. This allows for greater elongation of the skirt and avoids undesirable deformation of the struts when the valve is crimped.

In addition, the spacing between the woven fibers or yarns can be increased to facilitate elongation of the skirt in the axial direction. For example, for a PET skirt <NUM> formed from <NUM>-denier yarn, the yarn density can be about <NUM>% to about <NUM>% less than a conventional PET skirt. In some examples, the yarn spacing of the skirt <NUM> can be from about <NUM> yarns per inch to about <NUM> yarns per inch, such about <NUM> yarns per inch, whereas in a conventional PET skirt the yarn spacing can be from about <NUM> yarns per inch to about <NUM> yarns per inch. The oblique edges <NUM>, <NUM> promote uniform and even distribution of the fabric material along inner circumference of the frame during crimping so as to minimize bunching of the fabric to facilitate uniform crimping to the smallest possible diameter. Additionally, cutting diagonal sutures in a vertical manner may leave loose fringes along the cut edges. The oblique edges <NUM>, <NUM> help minimize this from occurring. As noted above, <FIG> shows a crimped valve with a conventional skirt that has fibers that run perpendicular to the upper and lower edges of the skirt. Comparing <FIG>, it is apparent that the construction of skirt <NUM> avoids undesirable deformation of the frame struts and provides more uniform crimping of the frame.

In alternative embodiments, the skirt can be formed from woven elastic fibers that can stretch in the axial direction during crimping of the valve. The warp and weft fibers can run perpendicular and parallel to the upper and lower edges of the skirt, or alternatively, they can extend at angles between <NUM> and <NUM> degrees relative to the upper and lower edges of the skirt, as described above.

The inner skirt <NUM> can be sutured to the frame <NUM> at locations away from the suture line <NUM> so that the skirt can be more pliable in that area (see <FIG>). This can avoid stress concentrations at the suture line <NUM>, which attaches the lower edges of the leaflets to the skirt <NUM>.

As noted above, the leaflet structure <NUM> in the illustrated embodiment includes three flexible leaflets <NUM> (although a greater or fewer number of leaflets can be used). As best shown in <FIG>, each leaflet <NUM> in the illustrated configuration has an upper (outflow) free edge <NUM> extending between opposing upper tabs <NUM> on opposite sides of the leaflet. Below each upper tab <NUM> there is a notch <NUM> separating the upper tab from a corresponding lower tab <NUM>. The lower (inflow) edge portion <NUM> of the leaflet extending between respective ends of the lower tabs <NUM> includes vertical, or axial, edge portions <NUM> on opposites of the leaflets extending downwardly from corresponding lower tabs <NUM> and a substantially V-shaped, intermediate edge portion <NUM> having a smooth, curved apex portion <NUM> at the lower end of the leaflet and a pair of oblique portions <NUM> that extend between the axial edge portions and the apex portion. The oblique portions can have a greater radius of curvature than the apex portion. Each leaflet <NUM> can have a reinforcing strip <NUM> secured (e.g., sewn) to the inner surface of the lower edge portion <NUM>, as shown in <FIG>.

The leaflets <NUM> can be secured to one another at their adjacent sides to form commissures <NUM> of the leaflet structure. A plurality of flexible connectors <NUM> (one of which is shown in <FIG>) can be used to interconnect pairs of adjacent sides of the leaflets and to mount the leaflets to the commissure window frame portions <NUM>. The flexible connectors <NUM> can be made from a piece of woven PET fabric, although other synthetic and/or natural materials can be used. Each flexible connector <NUM> can include a wedge <NUM> extending from the lower edge to the upper edge at the center of the connector. The wedge <NUM> can comprise a non-metallic material, such as a rope or a piece of Ethibond <NUM>-<NUM> suture material, secured to the connector with a temporary suture <NUM>. The wedge <NUM> helps prevent rotational movement of the leaflet tabs once they are secured to the commissure window frame portions <NUM>. The connector <NUM> can have a series of inner notches <NUM> and outer notches <NUM> formed along its upper and lower edges.

<FIG> shows the adjacent sides of two leaflets <NUM> interconnected by a flexible connector <NUM>. The opposite end portions of the flexible connector <NUM> can be placed in an overlapping relationship with the lower tabs <NUM> with the inner notches <NUM> aligned with the vertical edges of the tabs <NUM>. Each tab <NUM> can be secured to a corresponding end portion of the flexible connector <NUM> by suturing along a line extending from an outer notch <NUM> on the lower edge to an outer notch <NUM> on the upper edge of the connector. Three leaflets <NUM> can be secured to each other side-to-side using three flexible connectors <NUM>, as shown in <FIG>.

Referring now to <FIG> and <FIG>, the adjacent sub-commissure portions <NUM> of two leaflets can be sutured directly to each other. In the example shown, PTFE-<NUM>-<NUM> suture material is used to form in-and-out stitches <NUM> and comb stitches <NUM> that extend through the sub-commissure portions <NUM> and the reinforcing strips <NUM> on both leaflets. The two remaining pairs of adjacent sub-commissure portions <NUM> can be sutured together in the same manner to form the assembled leaflet structure <NUM>, which can then be secured to the frame <NUM> in the following manner.

As noted above, the inner skirt <NUM> can be used to assist in suturing the leaflet structure <NUM> to the frame. As shown in <FIG>, the skirt <NUM> can have an undulating temporary marking suture <NUM> to guide the attachment of the lower edges of each leaflet <NUM>. The skirt <NUM> itself can be sutured to the struts of the frame <NUM> using sutures <NUM>, as noted above, before securing the leaflet structure <NUM> to the skirt <NUM>. The struts that intersect the marking suture <NUM> desirably are not attached to the skirt <NUM>. This allows the skirt <NUM> to be more pliable in the areas not secured to the frame and minimizes stress concentrations along the suture line that secures the lower edges of the leaflets to the skirt. The portion of the skirt <NUM> demarcated by rectangle <NUM> initially is left unsecured to the frame <NUM>, and is later secured to the frame after the leaflet structure <NUM> is secured to the skirt, as further described below. As noted above, when the skirt is secured to the frame, the fibers <NUM>, <NUM> of the skirt (see <FIG>) generally align with the angled struts of the frame to promote uniform crimping and expansion of the frame.

<FIG> is a cross-sectional view of a portion of the frame and leaflet structure showing the adjacent tab portions of two leaflets secured to a corresponding window frame portion <NUM>. <FIG> show one specific approach for securing the commissure portions <NUM> of the leaflet structure <NUM> to the commissure window frame portions <NUM> of the frame. First, as shown in <FIG>, the flexible connector <NUM> securing two adjacent sides of two leaflets is folded widthwise and the upper tab portions <NUM> are folded downwardly against the flexible connector. As best shown in <FIG> and <FIG>, each upper tab portion <NUM> is creased lengthwise (vertically) to assume an L-shape having an inner portion <NUM> folded against the inner surface of the leaflet and an outer portion <NUM> folded against the connector <NUM>. The outer portion <NUM> can then be sutured to the connector <NUM> along a suture line <NUM>. Next, as shown in <FIG>, the commissure tab assembly (comprised of a pair of lower tab portions <NUM> connected by connector <NUM>) is inserted through the commissure window <NUM> of a corresponding window frame portion <NUM>. <FIG> is a side view of the frame <NUM> showing the commissure tab assembly extending outwardly through the window frame portion <NUM>.

As best shown in <FIG> and <FIG>, the commissure tab assembly is pressed radially inwardly at the wedge <NUM> such that one of the lower tab portions <NUM> and a portion of the connector <NUM> is folded against the frame <NUM> on one side of the window frame portion <NUM> and the other lower tab portion <NUM> and a portion of the connector <NUM> is folded against the frame <NUM> on other side of the window frame portion <NUM>. A pair of suture lines <NUM> are formed to retain the lower tab portions <NUM> against the frame <NUM> in the manner shown in <FIG>. Each suture line <NUM> extends through connector <NUM>, a lower tab portion <NUM>, the wedge <NUM>, and another portion of connector <NUM>. Then, as shown in <FIG> and <FIG>, each lower tab portion <NUM> is secured to a corresponding upper tab portion <NUM> with a primary suture line <NUM> that extends through one layer of connector <NUM>, the lower tab portion <NUM>, another layer of connector <NUM>, another layer of connector <NUM>, and the upper tab portion <NUM>. Finally, as shown in <FIG> and <FIG>, the suture material used to form the primary suture line <NUM> can be used to further form whip stitches <NUM> at the edges of the tab portions <NUM>, <NUM> that extend through two layers of connector <NUM> sandwiched between tab portions <NUM>, <NUM>.

As shown in <FIG> and <FIG>, the folded down upper tab portions <NUM> form a double layer of leaflet material at the commissures. The inner portions <NUM> of the upper tab portions <NUM> are positioned flat abutting layers of the two leaflets <NUM> forming the commissures, such that each commissure comprises four layers of leaflet material just inside of the window frames <NUM>. This four layered portion of the commissures can be more resistant to bending, or articulating, than the portion of the leaflets <NUM> just radially inward from the relatively more rigid four layered portion. This causes the leaflets <NUM> to articulate primarily at inner edges <NUM> of the folded-down inner portions <NUM> in response to blood flowing through the valve during operation within the body, as opposed to articulating about the axial struts of the window frames <NUM>. Because the leaflets articulate at a location spaced radially inwardly from the window frames <NUM>, the leaflets can avoid contact with and damage from the frame. However, under high forces, the four layered portion of the commissures can splay apart about a longitudinal axis <NUM> (<FIG>) adjacent to the window frame <NUM>, with each inner portion <NUM> folding out against the respective outer portion <NUM>. For example, this can occur when the valve <NUM> is compressed and mounted onto a delivery shaft, allowing for a smaller crimped diameter. The four layered portion of the commissures can also splay apart about axis <NUM> when the balloon catheter is inflated during expansion of the valve, which can relieve some of the pressure on the commissures caused by the balloon and so the commissures are not damaged during expansion.

After all three commissure tab assemblies are secured to respective window frame portions <NUM>, the lower edges of the leaflets <NUM> between the commissure tab assemblies can be sutured to the inner skirt <NUM>. For example, as shown in <FIG>, each leaflet <NUM> can be sutured to the skirt <NUM> along suture line <NUM> using, for example, Ethibond thread. The sutures can be in-and-out sutures extending through each leaflet <NUM>, the skirt <NUM> and each reinforcing strip <NUM>. Each leaflet <NUM> and respective reinforcing strip <NUM> can be sewn separately to the skirt <NUM>. In this manner, the lower edges of the leaflets are secured to the frame <NUM> via the skirt <NUM>. As shown in <FIG>, the leaflets can be further secured to the skirt with blanket sutures <NUM> that extend through each reinforcing strip <NUM>, leaflet <NUM> and the skirt <NUM> while looping around the edges of the reinforcing strips <NUM> and leaflets <NUM>. The sutures <NUM> can be formed from PTFE suture material. <FIG> show the frame <NUM>, leaflet structure <NUM> and the skirt <NUM> after securing the leaflet structure and the skirt to the frame and the leaflet structure to the skirt.

<FIG> shows a flattened view of the outer skirt <NUM> prior to its attachment to the frame <NUM>. The outer skirt <NUM> can be laser cut or otherwise formed from a strong, durable piece of material, such as woven PET, although other synthetic or natural materials can be used. The outer skirt <NUM> can have a substantially straight lower edge <NUM> and an upper edge <NUM> defining a plurality of alternating projections <NUM> and notches <NUM>. As best shown in <FIG>, the lower edge <NUM> of the skirt <NUM> can be sutured to the lower edge of the inner skirt <NUM> at the inflow end of the valve. As shown in <FIG>, each projection <NUM> can be sutured to the second rung II of struts <NUM> of the frame <NUM>. The corners <NUM> of the projections <NUM> can be folded over respective struts of rung II and secured with sutures <NUM>.

As can be seen in <FIG> and <FIG>, the outer skirt <NUM> is secured to the frame <NUM> such that when the frame is in its expanded state, there is excess material or slack between the outer skirt's lower and upper edges <NUM>, <NUM> that does not lie flat against the outer surface of the frame <NUM>. In other words, the outer skirt is configured with excess material which causes the outer skirt to bulge outwardly as the frame foreshortens (i.e., shortens in length) during radial expansion. Accordingly, when the valve <NUM> is deployed within the body, the excess material of the outer skirt <NUM> can fill in gaps between the frame <NUM> and the surrounding native annulus to assist in forming a good fluid-tight seal between the valve and the native annulus. The outer skirt <NUM> therefore cooperates with the inner skirt <NUM> to avoid perivalvular leakage after implantation of the valve <NUM>. In another advantageous feature, the slack between the lower and upper edges of the outer skirt <NUM> allows the frame <NUM> to elongate axially during crimping without any resistance from the outer skirt and the outer skirt does not substantially affect the outer diameter of the prosthetic valve in the crimped condition.

<FIG> shows the valve <NUM> of <FIG> and <FIG> mounted on an elongated shaft <NUM> of a delivery apparatus, forming a delivery assembly for implanting the valve <NUM> in a patient's body. The valve <NUM> is mounted in a radially collapsed configuration for delivery into the body. The shaft <NUM> comprises an inflatable balloon <NUM> for expanding the balloon within the body, the crimped valve <NUM> being positioned over the deflated balloon. The frame <NUM> of the valve <NUM>, when in the radially compressed, mounted configuration, comprises an inflow end portion <NUM> (see <FIG>) that has an outer diameter D<NUM> that is smaller than the outer diameter D<NUM> of the outflow end portion of the frame. The tapering of the frame can be at least partially due to the V-shaped leaflets <NUM>, as the V-shaped leaflets have less leaflet material within the inflow end portion of the frame <NUM> compared to a more rounded, U-shaped leaflet. Due to the tapered shape of the frame <NUM> in the mounted state, even with the additional thickness of the outer skirt <NUM> positioned around the inflow end portion <NUM> of the frame <NUM> the overall outer diameter of the inflow end portion of the valve <NUM> can be about equal to, or less than, the overall outer diameter of the outflow end portion of the valve.

Furthermore, as shown in <FIG>, the valve <NUM> comprises commissure portions of the leaflets extending radially outwardly through corresponding window frame portion <NUM> to locations outside of the frame and sutured to the side struts of the commissure window frame. To minimize the crimp profile of the valve, the window frame portions <NUM> can be depressed radially inwardly relative to the surrounding portions of the frame, such as the frame portions extending between adjacent commissure windows, when the valve is radially compressed to the collapsed configuration on the shaft. For example, the commissure windows <NUM> of the frame can be depressed inwardly a radial distance of between <NUM> and <NUM> relative to the portions of the frame extending between adjacent commissure windows when the valve is radially collapsed. In this way, the outer diameter of the outflow end portion the valve comprising the commissure portions can be generally consistent, as opposed to the commissure portions jutting outward from the surrounding portions of the valve, which could hinder delivery of the valve into the body. Even with the radially depressed commissure window frames <NUM>, the outer diameter of the inflow end portion of the frame can still be smaller than, or about equal to, the outer diameter of the outflow end portion of the frame when the valve is radially collapsed on the shaft, allowing for a minimal maximum overall diameter of the valve. By minimizing the diameter of the valve when mounted on the delivery shaft, the assembly can contained within a smaller diameter catheter and thus can be passed through smaller vessels in the body and can be less invasive in general.

<FIG> illustrates a prosthetic heart valve <NUM>. The heart valve <NUM> includes a frame, or stent, <NUM> and a leaflet structure <NUM> mounted on the stent. The leaflet structure <NUM> can include a plurality of leaflets <NUM> (e.g., three, as depicted), which can be sutured to each other and to the frame <NUM> using suitable techniques and/or mechanisms. The frame <NUM> can be adapted to include commissure frame portions <NUM> (as shown in <FIG>) to assist in suturing the leaflets to the frame.

The frame <NUM> shares some design features of the frame <NUM> described above. In particular, like frame <NUM>, the frame <NUM> has relatively large frame openings <NUM> along the area of the frame that supports the leaflet structure, as shown in <FIG>. The openings <NUM> are defined by a row of angled struts <NUM> at the outflow end of the frame, a plurality of axially extending, circumferentially spaced struts <NUM>, and an intermediate row of angled struts <NUM>. As shown, the axial struts <NUM> desirably are thinner than the junctions <NUM> connecting the opposite ends of the axial struts <NUM> to the convergence of two struts <NUM> and to the convergence of two struts <NUM>. By virtue of this configuration, the width of openings <NUM> remain large enough when the valve is radially compressed to a delivery configuration to allow portions of the leaflet structure <NUM> to protrude outwardly through the openings, as indicated at <NUM> in <FIG>. This allows the valve to be crimped to a relatively smaller diameter than if all of the leaflet material is constrained within the crimped frame.

For purposes of comparison, <FIG> is a cross section of a known prosthetic valve <NUM> showing the valve in its crimped state. When the valve is radially compressed, the spacing between adjacent struts is relatively small and does not allow portions of the leaflet structure to protrude outwardly through the frame. Consequently, the presence of all of the leaflet material being constrained within the inside of the frame limits the crimping diameter of the valve.

<FIG> show a flattened section of an alternative frame construction that can allow portions of the leaflets to protrude outwardly through the frame in the crimped state. This frame construction can be implemented in the valve <NUM> described above. <FIG> shows the frame section in the radially compressed state while <FIG> shows the frame section in the radially expanded state. The frame (only a portion of which is shown) includes a first, circumferentially extending row of angled struts <NUM> and at least a second, circumferentially extending row of angled struts <NUM>. Some openings in the frame are diamond shaped openings <NUM> formed by adjacent struts <NUM> connected to each other at their upper ends and adjacent struts <NUM> connected to each other at their lower ends. The frame also includes larger openings <NUM> that are formed by adjacent struts <NUM> connected at their upper ends to respective ends of a horizontal strut <NUM> and by adjacent struts <NUM> connected at their lower ends to respective ends of a horizontal strut <NUM>. When the frame is radially compressed, the horizontal struts <NUM>, <NUM> maintains the width W of openings <NUM> large enough to permit portions of the valve's leaflets to protrude outwardly through the frame. Thus, the width of openings <NUM> is greater than the width of openings <NUM> when the frame is crimped. The frame can be formed with openings <NUM>, <NUM> alternating around the circumference of the frame. Alternatively, openings <NUM> can be located at selected positions along the frame's length and circumference to correspond to areas where the leaflet material tend to bunch up within the frame, such as between the commissures.

<FIG> show a flattened section of another frame construction that can allow portions of the leaflets to protrude outwardly through the frame in the crimped state. This frame construction can be implemented in the valve <NUM> described above. <FIG> shows the frame section in the radially compressed state while <FIG> shows the frame section in the radially expanded state. The frame (only a portion of which is shown) includes a first, circumferentially extending row of angled struts <NUM> and at least a second, circumferentially extending row of angled struts <NUM>. Some openings in the frame are diamond shaped openings <NUM> formed by adjacent struts <NUM> connected to each other at their upper ends and adjacent struts <NUM> connected to each other at their lower ends. The frame also includes openings <NUM> that are formed by adjacent struts <NUM> connected at their upper ends to an enlarged node or junction <NUM> and by adjacent struts <NUM> connected at their lower ends to an enlarged node or junction <NUM>. The junctions <NUM>, <NUM> add rigidity to the frame at those locations such that when the frame is radially compressed, the width W of openings <NUM> remains large enough to permit portions of the valve's leaflets to protrude outwardly through the frame. Thus, the width of openings <NUM> is greater than the width of openings <NUM> when the frame is crimped. The frame can be formed with openings <NUM>, <NUM> alternating around the circumference of the frame. Alternatively, openings <NUM> can be located at selected positions along the frame's length and circumference to correspond to areas where the leaflet material tend to bunch up within the frame, such as between the commissures.

<FIG> shows a leaflet <NUM> for a prosthetic valve (e.g., valve <NUM> or <NUM>), according to another embodiment. The leaflet <NUM> has an overall V-shape, similar to leaflets <NUM> described above. The leaflet <NUM> has two tab portions <NUM> on opposite sides of the leaflets which are secured to adjacent tab portions of other leaflets to form the commissures of the leaflet structure. The sub-commissure portion of the leaflet <NUM> (the portion below the tabs <NUM>) include two substantially straight edges <NUM> that extend from respective locations just below the tabs <NUM> to a curved lower edge <NUM>. <FIG> shows the general shape of the leaflet <NUM> when the valve is crimped. The frame (not shown in <FIG>) slightly elongates when crimped, causing the leaflet <NUM> to become slightly elongated.

The tapered profile of the sub-commissure portion of the leaflet reduces the amount of leaflet material in the lower half of the crimped valve to minimize the crimp diameter of that portion of the valve. Thus, if additional components are mounted to that portion of the valve, such as an outer skirt <NUM>, the reduced profile of that portion of the valve can help offset or minimize the increase in diameter caused by the additional component. Additionally, the commissure tabs <NUM> are relatively short and require less sutures for forming the commissures of the leaflet structure than known leaflet designs (such as T-shaped and scalloped leaflets), which better distributes and reduces the bulkiness of the leaflet material when the valve is crimped.

<FIG> shows a cross-sectional view of a valve <NUM>, according to another embodiment. The valve <NUM> comprises a frame <NUM>, leaflets <NUM>, and an outer skirt <NUM> mounted (e.g., by sutures) to the outer surface of the frame <NUM>. The frame <NUM> has a thickness that varies along its length to optimize strength where needed, yet minimize material (and therefore crimp profile) at selected regions of the frame. In the embodiment shown, the outflow end portion <NUM> of the frame has a maximum thickness T<NUM> (measured from the inside diameter to the outside diameter of that portion of the frame) and the inflow end portion <NUM> of the frame has a minimum thickness T<NUM> (measured from the inside diameter to the outside diameter of that portion of the frame). It should be noted that the struts of the frame <NUM> (which are not shown in <FIG>) that form the outflow end portion <NUM> have a thickness T<NUM> and the struts that form the inflow end portion <NUM> have a thickness T<NUM>. The frame <NUM> can have an identical construction to the frame <NUM> described above, except for the variable thickness of the frame. The areas of reduced thickness can be formed using a variety of manufacturing techniques, such as electro-polishing selected portions of the frame (the non-polished portions can be masked), grinding selected portions of the frame, wire cutting, or other suitable techniques.

The outflow end portion <NUM> generally corresponds to the region of the frame that supports the commissures of the leaflets <NUM> and typically experiences the greatest loading on the valve. Therefore the outflow end portion <NUM> of the frame has a greater thickness T<NUM> selected to provide the required strength under anticipated loads. The inflow end portion <NUM> supports an additional layer of material by virtue of the outer skirt <NUM>. The reduced thickness of the inflow end portion <NUM> allows the inflow end portion to be crimped to a smaller diameter than the outflow end portion. This offsets or minimizes the increase in the crimp diameter caused by the addition of the outer skirt <NUM>.

<FIG> show an another embodiment of an implantable prosthetic valve <NUM> that comprises a leaflet structure <NUM> and a radially collapsible and expandable frame <NUM> (similar to the frame <NUM> shown in <FIG>) having a plurality of radially spaced commissure windows <NUM> that are used to secure the leaflet structure within the frame. The valve <NUM> also comprises a skirt <NUM> secured between the inner surface of the frame <NUM> and the curved lower edges <NUM> of the leaflet structure <NUM>. The valve <NUM> has a lower, inflow end <NUM> and an upper, outflow end <NUM>.

As shown in <FIG>, each window <NUM> comprises an enclosed opening <NUM> between two axially extending side struts <NUM>, respectively. Each side strut comprises a generally rectangular, e.g. square, cross-sectional profile, as shown in <FIG>. Each rectangular side strut <NUM> comprises four surfaces: an exterior surface <NUM> on a radially outward facing side, and interior surface <NUM> on a radially inward facing side, a medial surface <NUM> on a side facing the other side strut, and a lateral surface <NUM> on a side facing away from the other side strut. In other embodiments, side struts can comprise other cross-sectional shapes, such circular or hexagonal.

The leaflet structure comprises a plurality of leaflets <NUM>, each comprising a pair of side tabs <NUM> secured to the frame <NUM>, a curved lower edge <NUM> secured to the skirt <NUM>, and an articulation portion <NUM> between the side tabs and the lower edge. Each side tab <NUM> is paired with an adjacent side tab of another leaflet <NUM> to form commissures <NUM> of the leaflet structure <NUM>. Each pair of side tabs <NUM> extends radially outwardly through a corresponding commissure window <NUM> to a location outside of the frame <NUM> and is secured to the side struts <NUM> of the window, such as with sutures, as shown in <FIG>. In some embodiments, each side tab <NUM> comprises an end portion <NUM> (see <FIG>) and the two side tab end portions <NUM> of each commissure <NUM> extend circumferentially away from one another and along the exterior surfaces <NUM> of respective side struts <NUM> of the window <NUM>.

In some embodiments, each commissure <NUM> further comprises at least one non-rigid reinforcing sheet <NUM> sutured to the side tabs <NUM> and to the side struts <NUM>. The sheets <NUM> can comprise a flexible, tear resistant material, including a variety of natural and/or synthetic biocompatible materials. Exemplary synthetic materials can include polymers such as nylon, silicone, and polyesters, including PET. In one example, the sheets <NUM> comprise a woven PET fabric.

Each reinforcing sheet <NUM> can be generally rectangular (when laid flat) and can comprise a middle portion <NUM> and opposing end portions <NUM>. In some embodiments, a first end portion <NUM> of the sheet is secured to a first side strut <NUM> and a second end portion <NUM> of the sheet is secured to the second side strut <NUM>, as shown in <FIG>. The sheet <NUM> separates the side tabs <NUM> from the side struts <NUM> such that side tabs do not contact the side struts. For example, each end portion <NUM> of the sheet can be wrapped completely around a respective side strut <NUM>, as shown in <FIG>.

The side tabs <NUM> and the reinforcing sheet <NUM> can be secured to the side struts <NUM> in multiple stages. For example, <FIG> shows an exemplary first suturing stage wherein the sheet is positioned such that the middle portion <NUM> of the sheet extends circumferentially across outer surfaces of the end portions <NUM> of the side tabs <NUM> and each end portion <NUM> of the sheet extends between a respective side tab <NUM> and the exterior, medial and interior surfaces <NUM>, <NUM>, <NUM>, respectively, of a respective side strut <NUM>. The sheet <NUM> surrounds the side tabs <NUM> and protects the side tabs from edges of the side struts <NUM>. A pair of in-and-out sutures <NUM> can secure each side tab <NUM> and one end of the sheet <NUM> to a respective strut <NUM>. As shown in <FIG>, each suture <NUM> can be oriented generally perpendicularly to the circumference of the frame <NUM> along the lateral surfaces <NUM> of the side struts <NUM> and can pass radially back and forth through the commissure <NUM> at a plurality of difference longitudinal positions. Each suture <NUM> can intersect a first layer of the sheet <NUM>, a side tab end portion <NUM>, a second layer of the sheet, and a third layer of the sheet, in that order moving radially inward. The sutures <NUM> secure the sheet <NUM> to the side tab end portions <NUM> and tighten the sheet end portions <NUM> around the side struts <NUM>, thereby securing the side tabs <NUM> to the side struts <NUM> and securing the leaflet structure <NUM> to the frame <NUM>.

<FIG> shows an exemplary second suturing stage wherein a second pair of sutures <NUM> are used to tie down loose portions of the reinforcing sheet <NUM>. For example, the second sutures <NUM> can intersect the portions of the middle portion <NUM> and the end portions <NUM> of the sheet that extend laterally beyond the first sutures <NUM>. The second sutures <NUM> can be helical whip stitches that intersect the commissures <NUM> at a plurality of different longitudinal positions, as shown in <FIG>, and secure the loose portions of the sheet <NUM> tightly against the lateral surfaces <NUM> of the side struts.

Both the first sutures <NUM> and the second sutures <NUM> can be positioned adjacent to the lateral surfaces <NUM> of the struts <NUM> and spaced away from the window opening <NUM>. This placement of the sutures can reduce the stress on the sutures caused by movement of the articulation portions <NUM> of the leaflets. Instead, much of this stress is transferred from flex hinges <NUM> of the leaflets to the side struts <NUM> near interior-medial edges <NUM> of the struts.

The reinforcing sheet <NUM> protects the flex hinges <NUM> from damage caused by the interior-medial edges <NUM> of the struts <NUM> as the leaflets articulate between open and closed positions, as shown in <FIG>. In addition, some embodiments can also include longitudinally extending cushion strips <NUM> positioned between the flex hinges <NUM> and the struts <NUM>, such as adjacent to the interior-medial edges <NUM>, as shown in <FIG>, to further protect the flex hinges from damage caused by the struts. The cushion strips <NUM> can comprise a flexible, compressible material, such as PET fabric, pericardial tissue, or various other biocompatible materials. In some embodiments, the cushion strips can comprise a tube filled with a resilient material. For example, the cushion strip can comprise a PET tube filled with pericardial tissue. In other embodiments, the outer tubular covering of the cushion strips can be formed from sheet <NUM> and can be filled with a resilient material. The sheet can be secured around the resilient material with sutures to retain the cushioning strips properly located as shown in <FIG>. In other embodiments, separate cushion strips <NUM> can be sutured to the reinforcing sheet <NUM>. The cushion strips <NUM> can have a thickness similar to the bars <NUM> to provide a radial clearance between the side struts <NUM> and the articulating portions <NUM> of the leaflets to prevent or minimize contact between the leaflets and the inner surface of the frame during the cardiac cycle.

<FIG> shows an embodiment similar to <FIG> but with a different suturing pattern. In <FIG>, the sutures <NUM> are replaced with sutures <NUM> that secure the sheet <NUM> around the end portions <NUM> of the side tabs. Each suture <NUM> intersects the middle portion <NUM> of the sheet, one of the side tabs <NUM>, and a second layer of the sheet adjacent to the medial-exterior edge <NUM> of each side strut. The sutures <NUM> can comprise in-and-out stitches that intersect the commissures at a plurality of different longitudinal positions. Each end portion of the sheet <NUM> can comprise a folded portion <NUM> that is folded under to form a double layer of the sheet <NUM> along the surface of the respective side strut <NUM>. The sutures <NUM> secure the end portions <NUM> of the sheet and the end portions <NUM> of the side tabs tightly around the lateral surfaces <NUM> of the side struts.

<FIG> show an alternative method for suturing the side tabs <NUM> and the sheet <NUM> to the side struts <NUM>. <FIG> shows suture line <NUM> positioned along the exterior surfaces <NUM> of the side struts and generally perpendicular to the radius of the frame. The suture <NUM> intersects both side tabs <NUM> and both end portions <NUM> of the sheet <NUM>. The suture <NUM> secures each end portion <NUM> of the sheet tightly around the medial, interior, and lateral surfaces <NUM>, <NUM>, <NUM>, respectively, of the respective side strut <NUM>, and also secures the middle portion <NUM> of the sheet loosely around the end portions <NUM> of the side tabs <NUM>. In the embodiment shown in <FIG>, the suture <NUM> intersects a first sheet layer A, a second sheet layer B, the two side tabs <NUM>, a third sheet layer C, and a fourth sheet layer D, in that order.

After the first suture <NUM> is in place, the end portions <NUM> of the side tabs are spread apart and positioned adjacent to the exterior surfaces <NUM> of the side struts <NUM>, as shown in <FIG>. This tightens the loose middle portion <NUM> of the sheet around the end portions <NUM> of the side tabs. A pair of sutures <NUM> can then secure the middle portion <NUM> of the sheet tightly to the end portions <NUM> of the sheet to hold the end portions <NUM> of the side tabs in place, as shown in <FIG>. The sutures <NUM> can be looping whip stitches that intersect the commissure <NUM> at a plurality of different longitudinal positions, similar to the sutures <NUM> in <FIG>.

<FIG> show another alternative method for suturing the side tabs <NUM> and the sheet <NUM> to the side struts <NUM>. <FIG> shows a suture line <NUM> positioned along the exterior side of the window opening and oriented generally perpendicular to the radius of the frame. The suture <NUM> intersects both side tabs <NUM> and two portions of the sheet <NUM>. The suture <NUM> secures the middle portion <NUM> of the sheet which extends loosely around the end portions <NUM> of the side tabs <NUM>. In the embodiment shown in <FIG>, the suture <NUM> intersects a first sheet layer A, a first side tab B, a second side tab C, and a second sheet layer D, in that order.

After the first suture <NUM> is in place, the end portions <NUM> of the side tabs are spread apart and positioned adjacent to the exterior surfaces <NUM> of the side struts <NUM>, as shown in <FIG>. This tightens the loose middle portion <NUM> of the sheet around the end portions <NUM> of the side tabs. A pair of sutures <NUM> can then secure the middle portion <NUM> of the sheet tightly to the end portions <NUM> of the sheet to hold the end portions <NUM> of the side tabs in place, as shown in <FIG>. The end portions <NUM> of the sheet can comprise a folded under portion <NUM>, creating a double layer of sheet material to reinforce the sutures <NUM>. The sutures <NUM> can be looping whip stitches that intersect the commissure <NUM> at a plurality of different longitudinal positions, similar to the sutures <NUM> in <FIG>.

<FIG> show yet another alternative method for suturing the side tabs <NUM> and the sheet <NUM> to the side struts <NUM>. <FIG> shows the suture line <NUM> positioned along the exterior side of the window opening and oriented generally perpendicular to the radius of the frame. The suture <NUM> intersects both side tabs <NUM> and four portions or layers of the sheet <NUM>. Each end portion <NUM> of the sheet comprises a folded portion <NUM> that forms a double layer of sheet material between the side tabs <NUM> and the medial surfaces <NUM> of the side struts. The suture <NUM> secures the middle portion <NUM> of the sheet loosely around the end portions <NUM> of the side tabs <NUM>. As shown in <FIG>, each stitch of the suture <NUM> intersects a first pair of sheet layers comprising layers A and B, a first side tab C, a second side tab D, and a second pair of sheet layers comprising layers E and F, in that order.

After the first suture <NUM> is in place, the end portions <NUM> of the side tabs are spread apart and positioned adjacent to the exterior surfaces <NUM> of the side struts <NUM>, as shown in <FIG>. This tightens the middle portion <NUM> of the sheet around the end portions <NUM> of the side tabs. A pair of sutures <NUM> can then secure the middle portion <NUM> of the sheet tightly to the end portions <NUM> of the sheet to hold the end portions <NUM> of the side tabs in place, as shown in <FIG>. The folded portions <NUM> of the sheet create a double layer of sheet material to reinforce the sutures <NUM>. The sutures <NUM> can be looping whip stitches that intersect the commissure <NUM> at a plurality of different longitudinal positions, similar to the sutures <NUM> in <FIG>.

The commissure various configurations for attaching the leaflet structure <NUM> to the window frames <NUM> shown in <FIG> can also be used as alternative ways to attach the leaflet structure <NUM> of the valve <NUM> of <FIG> to the window frame portions <NUM> of frame <NUM>.

<FIG> show a prosthetic heart valve assembly <NUM> comprising an embodiment of a frame <NUM> for a prosthetic valve mounted on a balloon <NUM> of a delivery shaft <NUM>. The frame <NUM> can be similar in shape to the frame <NUM> and can comprise in inflow end portion <NUM>, an outflow end portion <NUM> and an intermediate portion <NUM>. For clarity, the other components of the valve, such as the leaflets and the skirts, are not shown. The frame <NUM> can have a reduced thickness at the inflow end portion <NUM> and at the outflow end portion <NUM>, relative to the thickness of the intermediate portion <NUM>. Due to the thinner end portions, when the balloon <NUM> is inflated the end portions <NUM>, <NUM> offer less resistance to expansion and expand faster than the intermediate portion <NUM>, as shown in <FIG>. Because the end portions expand faster than the intermediate portion, the frame <NUM> becomes confined on the balloon <NUM>, inhibiting the frame from sliding towards either end of the balloon and reducing the risk of the frame sliding off the balloon prematurely. As shown in <FIG>, further inflation of the balloon can cause the intermediate portion <NUM> of the frame to expand to the same final diameter as the end portions <NUM>, <NUM> for implantation, after which the balloon can be deflated and removed. Controlling the position of the valve on the balloon can be important during delivery, especially with frames that foreshorten during expansion and move relative to the balloon. In the embodiment shown in <FIG>, the intermediate portion <NUM> of the frame can be held constant relative to the balloon while the two end portions foreshorten towards the intermediate portion due to the "dog-bone" effect of the balloon. Any conventional means can be used to produce the frame <NUM> with reduced thickness at the end portions <NUM>, <NUM>, such as sanding down the end portions with sand paper or the like. In one embodiment, the end portions <NUM>, <NUM> of the frame have a thickness of about <NUM> while the intermediate portion <NUM> has a thickness of about <NUM>.

Claim 1:
An implantable prosthetic heart valve (<NUM>; <NUM>; <NUM>) that is collapsible to a collapsed configuration and expandable to an expanded configuration, the valve (<NUM>; <NUM>; <NUM>) comprising:
a balloon-expandable annular frame (<NUM>; <NUM>; <NUM>) having an inflow end portion (<NUM>; <NUM>; <NUM>) and an outflow end portion (<NUM>; <NUM>) and being formed from a plastically-expandable material including one or more of: stainless steel or a polymer or a nickel-cobalt-chromium alloy or combinations thereof, and
a leaflet structure (<NUM>; <NUM>; <NUM>) positioned within the frame (<NUM>; <NUM>; <NUM>),
wherein the frame (<NUM>; <NUM>; <NUM>) comprises:
an inflow row of openings (<NUM>) at the inflow end portion (<NUM>; <NUM>; <NUM>), an outflow row of openings (<NUM>) at the outflow end portion (<NUM>; <NUM>), and at least one intermediate row of openings (<NUM>) between the inflow row of openings (<NUM>) and the outflow row of openings (<NUM>), wherein the openings of the inflow row of openings (<NUM>) are larger than the openings of the at least one intermediate row of openings (<NUM>), wherein the openings (<NUM>) of the outflow row are larger than the openings (<NUM>) of the inflow row and the openings (<NUM>) of the at least one intermediate row; and
wherein the outflow row of openings (<NUM>) is formed by a first row of angled struts (<NUM>) and a second row of angled struts (<NUM>), connected to one another by a plurality of axially extending window frame portions (<NUM>) and a plurality of axially extending struts (<NUM>), said each of the plurality of axially extending window frame portions (<NUM>) configured to mount a respective commissure of the leaflet structure (<NUM>; <NUM>; <NUM>);
wherein each one of the plurality of axially extending window frame portions (<NUM>) and each one of the plurality of axially extending struts (<NUM>) extends from a first location defined by a convergence of two lower ends of two angled struts (<NUM>) of the first row of angled struts (<NUM>) to a second location defined by the convergence of two upper ends of two angled struts (<NUM>) of the second row of angled struts (<NUM>).