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. 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 example, collapsible transcatheter prosthetic heart valves can be crimped to a compressed state and percutaneously introduced in the compressed state on a catheter and expanded to a functional size at the desired position by balloon inflation or by utilization of a self-expanding frame or stent.

A prosthetic valve for use in such a procedure can include a radially collapsible and expandable frame to which leaflets of the prosthetic valve can be coupled. For example, <CIT>, <CIT>,<CIT>, and <CIT> describe exemplary collapsible transcatheter heart valves (THVs).

A challenge in catheter-implanted prosthetic valves is the process of crimping such a prosthetic valve to a profile suitable for percutaneous delivery to a subject. Another challenge is the control of paravalvular leakage around the valve, which can occur for a period of time following initial implantation.

Paravalvular leakage has been a known problem since the first replacement valves were introduced. The earliest prosthetic heart valves, those that were implanted surgically, included a circumferential sewing ring that was adapted to extend into spaces in the tissue surrounding the implanted prosthesis to prevent paravalvular leaking. For example, <CIT> describes a prosthetic heart valve for surgical implantation that includes a rubber "cushion ring" that conforms to irregularities of the tissue to form an effective seal between the valve and the surrounding tissue. From there, vascular stents or stent grafts were developed that could be implanted by non-surgical catheterization techniques. These stents included a fabric covering that allowed the stent to be used to isolate and reinforce the wall of a blood vessel from the lumen of the vessel. These fabric coverings served essentially the same purpose on stents as did the sealing rings on surgical heart valves-they reduced the risk of blood leaking between the prosthesis and the surrounding tissue. Multiple graft designs were developed that further enhanced the external seal to prevent blood from flowing between the graft and surrounding cardiovascular tissue. For example, <CIT> to Thornton discloses a seal secured to the outer surface of a stent that is adapted to occlude leakage flow externally around the stent wall between the outer surface and the endolumenal wall when the stent is deployed, by conforming to the irregular surface of the surrounding tissue. <CIT> similarly discloses a tubular prosthesis having a stent and one or more fabric "skirts" to seal against endoleaks. <CIT> also recognized the potential for endoleaks, and describes a stent graft having a cuff portion that has an external sealing zone that extends around the body of the stent to prevent leakage. The cuff portion could be folded over to create a pocket that collects any blood passing around the leading edge of the graft to prevent an endoleak.

Building on this technology, in the late <NUM>'s, the first permanent bioprosthetic heart valve was implanted using transcatheter techniques. <CIT> describes a THV comprising a valve mounted within a collapsible and expandable stent structure. Certain embodiments have additional graft material used along the external and internal surface of the THV. As with stent grafts, the covers proposed to be used with THVs were designed to conform to the surface of the surrounding tissue to prevent paravalvular leaks.

Like with stents, "cuffs" or other outer seals were used on THVs. <CIT>describes a self-expanding THV having a cuff portion extending along the outside of the stent. Upon collapse of the stent for delivery, the outer seal collapses to form pleats, then expands with the stent to provide a seal between the THV and the surrounding tissue.

Thereafter, a different THV design was described by Pavcnik in <CIT>. The enhanced sealing structure of Pavcnik is in the form of corner "flaps" or "pockets" secured to the stent at the edges of each "flap" or "pocket" and positioned at discrete locations around the prosthesis. The corner flap was designed to catch retrograde blood flow to provide a better seal between the THV and the vessel wall, as well as to provide an improved substrate for ingrowth of native tissue.

Thus, fabric and other materials used to cover and seal both internal and external surfaces of THVs and other endovascular prostheses such as stents and stent grafts are well known. These covers can be made with low-porosity woven fabric materials, as described, for example, by <CIT>. , which describes a valve stent having an outer cover that can conform to the living tissue surrounding it upon implantation to help prevent blood leakage.

Several more recent THV designs include a THV with an outer covering. <CIT> discloses a THV having a cuff portion wrapped around the outer surface of the support stent at the inlet. The cuff portion is rolled up over the edge of the frame so as to provide a "sleeve-like" portion at the inlet to form a cuff over the inlet that helps prevent blood leakage. <CIT> describes an internal cover that extends from the base of the valve to the lower end of the stent and then up the external wall of the stent so as to form an external cover. The single-piece cover could be made with any of the materials disclosed for making the valve structure, which include fabric (e.g., Dacron), biological material (e.g., pericardium), or other synthetic materials (e.g., polyethylene).

While covers used on the external surface of an endovascular prosthesis to prevent paravalvular leaking are well known, there remains a need for improved coverings that provide enhanced sealing while still providing a small profile suitable for percutaneous delivery to a patient.

In <CIT> embodiments of a radially collapsible and expandable prosthetic heart valve are disclosed. The prosthetic valve comprises an annular frame, leaflets, an inner skirt, and an outer skirt. The outer skirt is secured to the outside of the inflow end portion of the frame, the outer skirt having longitudinal slack that buckles outward radially when the valve is in the expanded configuration and which lies flat when the valve is in the collapsed configuration. The outer skirt is stiffer in the axial direction of the valve than in the circumferential direction of the valve. The outer skirt comprises a self-expandable fabric comprising fibers made of a shape memory material having a shape memory set to enhance the radially outward buckling of the outer skirt. Methods of crimping such valves to a collapsed or partially collapsed configuration are also disclosed.

Embodiments of a radially collapsible and expandable prosthetic valve are disclosed herein that include an improved outer skirt for reducing perivalvular leakage, as well as related methods and apparatuses including such prosthetic valves. In several embodiments, the disclosed prosthetic valves are configured as replacement heart valves for implantation into a subject.

According to the invention, as defined by claim <NUM>, a prosthetic heart valve comprises an annular frame comprising an inflow end and an outflow end and being radially compressible and expandable between a radially compressed configuration and a radially expanded configuration having a cylindrical shape, wherein the frame comprises a plurality of rows of angled struts arranged end-to-end and extending circumferentially. A first, uppermost row of angled struts and a second row of angled struts immediately adjacent to the first row of angled struts along with frame portions and struts define an upper row of cells defining openings. A leaflet structure is positioned within the frame and secured thereto. An outer skirt is mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient, wherein the outer skirt comprises an inflow edge portion and an outflow edge portion defining a plurality of alternating projections and notches that follow the shape of a row of angled struts of the frame, wherein the outer skirt is sized and shaped relative to the frame such that when the prosthetic valve is in its radially expanded state, the outer skirt fits snugly against the outer surface of the frame. An inner skirt is mounted on an inner surface of the frame, the inner skirt having an inflow edge portion that is secured to an inflow edge portion of the outer skirt, wherein an outflow edge portion of the inner skirt is secured to the second row of angled struts such that the openings of the upper row of cells are not covered by the inner skirt.

In one representative embodiment, a prosthetic heart valve comprises an annular frame that comprises an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further includes a leaflet structure positioned within the frame and secured thereto, and an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member can comprise a mesh layer and pile layer comprising a plurality of pile yarns extending outwardly from the mesh layer.

In some embodiments, the mesh layer comprises a knit or woven fabric.

In some embodiments, the pile yarns are arranged to form a looped pile.

In some embodiments, the pile yarns are cut to form a cut pile.

In some embodiments, the height of the pile yarns varies along a height and/or a circumference of the outer skirt.

In some embodiments, the pile yarns comprise a first group of yarns along an upstream portion of the outer skirt and a second group of yarns along a downstream portion of the outer skirt, wherein the yarns of the first group have a height that is less than a height of the yarns of the second group.

In some embodiments, the pile yarns comprise a first group of yarns along an upstream portion of the outer skirt and a second group of yarns along a downstream portion of the outer skirt, wherein the yarns of the first group have a height that is greater than a height of the yarns of the second group.

In some embodiments, the pile yarns comprise a first group of yarns along an upstream portion of the outer skirt, a second group of yarns along a downstream portion of the outer skirt, and a third group of yarns between the first and second group of yarns, wherein the yarns of the first and second groups have a height that is greater than a height of the yarns of the third group.

In some embodiments, the prosthetic heart valve further comprises an inner skirt mounted on an inner surface of the frame, the inner skirt having an inflow end portion that is secured to an inflow end portion of the outer sealing member.

In some embodiments, the inflow end portion of the inner skirt is wrapped around an inflow end of the frame and overlaps the inflow end portion of the outer sealing member on the outside of the frame.

In some embodiments, the mesh layer comprises a first mesh layer and the outer sealing member further comprises a second mesh layer disposed radially outside of the pile layer.

In some embodiments, the outer sealing member is configured to stretch axially when the frame is radially compressed to the radially compressed state.

In some embodiments, the mesh layer comprises warp yarns and weft yarns woven with the warp yarns, and the pile layer comprises the warp yarns or the weft yarns of the mesh layer that are woven or knitted to form the pile yarns.

In some embodiments, the mesh layer comprises a woven fabric layer and the pile layer comprises a separate pile layer that is stitched to the woven fabric layer.

In some embodiment, the mesh layer has a first height extending axially along the frame and the pile layer comprises a second height extending axially along the frame, wherein the first height is greater than the second height.

In some embodiment, the mesh layer extends closer to the outflow end of the frame than the pile layer.

In another representative embodiment, a prosthetic heart valve comprises an annular frame that comprises an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a leaflet structure positioned within the frame and secured thereto, an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member can comprise a fabric having a variable thickness.

In some embodiments, the thickness of the fabric layer varies along a height and/or a circumference of the outer sealing member.

In some embodiments, the fabric comprises a plush fabric.

In some embodiments, the fabric comprises a plurality of pile yarns and the height of the pile yarns varies along a height and/or a circumference of the outer skirt.

In another representative embodiment, a prosthetic heart valve comprises an annular frame that comprises an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a leaflet structure positioned within the frame and secured thereto, an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member can comprise a pile fabric comprising a plurality of pile yarns, wherein the density of the pile yarns varies in an axial direction and/or a circumferential direction along the sealing member.

In some embodiments, the pile yarns are arranged in circumferentially extending rows of pile yarns and the density of the pile yarns varies from row to row.

In some embodiments, the pile yarns are arranged in axially extending rows pile yarns and the density of the pile yarns varies from row to row.

In some embodiments, the sealing member comprises a mesh layer and a pile layer comprising the pile yarns. In some embodiments, the weave density of the mesh layer varies in an axial direction and/or a circumferential direction along the sealing member. In some embodiments, the mesh layer comprises one or more rows of higher-density mesh portions and one or more rows of lower-density mesh portions. The one or more rows of higher-density mesh portions and the one or more rows of lower-density mesh portions can be circumferentially extending rows and/or axially extending rows.

In another representative embodiment, a prosthetic heart valve comprises an annular frame that comprises an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a leaflet structure positioned within the frame and secured thereto, an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member comprises a textile formed from a plurality fibers arranged in a plurality of axially extending rows of higher stitch density interspersed between a plurality of axially extending rows of lower stitch density. The sealing member is configured to stretch axially between a first, substantially relaxed, axially foreshortened configuration when the frame is the radially expanded configuration and a second, axially elongated configuration when the frame is in the radially compressed configuration.

In some embodiments, each of the rows of higher stitch density can extend in an undulating pattern when the sealing member is in the axially foreshortened configuration. When the sealing member is in the axially elongated configuration, the rows of higher stitch density move from the undulating pattern toward a straightened pattern.

In another representative embodiment, a prosthetic heart valve comprises an annular frame that comprises an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a leaflet structure positioned within the frame and secured thereto, an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member comprises a fabric comprising a plurality of axially extending filaments and a plurality of circumferentially extending filaments. The sealing member is configured to stretch axially when the frame is radially compressed from the radially expanded configuration to the radially compressed configuration. The axially extending filaments move from a deformed or twisted state when the frame is in the radially expanded configuration to a less deformed or less twisted state when the frame is in the radially compressed configuration.

In some embodiments, the axially extending filaments are heat set in the deformed or twisted state.

In some embodiments, the thickness of the sealing member decreases when the axially extending filaments move from the deformed or twisted state to the less deformed or twisted state.

<FIG> shows a prosthetic heart valve <NUM>, according to one embodiment. The illustrated prosthetic 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 (e.g., the pulmonary, mitral, and tricuspid valves). The prosthetic valve can also be adapted to be implanted in other tubular organs or passageways in the body. The prosthetic valve <NUM> can have four main components: a stent or frame <NUM>, a valvular structure <NUM>, an inner skirt <NUM>, and a perivalvular outer sealing member or outer skirt <NUM>. The prosthetic valve <NUM> can have an inflow end portion <NUM>, an intermediate portion <NUM>, and an outflow end portion <NUM>.

The valvular structure <NUM> can comprise three leaflets <NUM> (<FIG>), collectively forming a leaflet structure, which can be arranged to collapse in a tricuspid arrangement. 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 prosthetic 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 prosthetic 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., nickel titanium alloy (NiTi), such as nitinol) as known in the art. When constructed of a plastically-expandable material, the frame <NUM> (and thus the prosthetic valve <NUM>) can be crimped to a radially collapsed configuration 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 prosthetic valve <NUM>) can be crimped to a radially collapsed configuration and restrained in the collapsed configuration by insertion into a sheath or equivalent mechanism of a delivery catheter. Once inside the body, the prosthetic valve can be advanced from the delivery sheath, which allows the prosthetic 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 biocompatible, high-strength alloys (e.g., a cobalt-chromium or a nickel-cobalt-chromium alloys), polymers, or combinations thereof. In particular embodiments, frame <NUM> is made of a nickel-cobalt-chromium-molybdenum alloy, such as MP35N® alloy (SPS Technologies, Jenkintown, Pennsylvania), which is equivalent to UNS R30035 alloy (covered by ASTM F562-<NUM>). MP35N® alloy/UNS R30035 alloy comprises <NUM>% nickel, <NUM>% cobalt, <NUM>% chromium, and <NUM>% molybdenum, by weight. It has been found that the use of MP35N® alloy to form frame <NUM> provides superior structural results over stainless steel. In particular, when MP35N® alloy 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 prosthetic 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 prosthetic 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 prosthetic 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 S1 that is less than the thicknesses S2 of the junctions <NUM>, <NUM>. The junctions <NUM>, <NUM>, along with junctions <NUM>, prevent full closure of openings <NUM>. The geometry of the struts <NUM>, and junctions <NUM>, <NUM>, and <NUM> assists in creating enough space in openings <NUM> in the collapsed configuration to allow portions of the prosthetic leaflets to protrude or bulge outwardly through openings. This allows the prosthetic valve to be crimped to a relatively smaller diameter than if all of the leaflet material were constrained within the crimped frame.

The frame <NUM> is configured to reduce, to prevent, or to minimize possible over-expansion of the prosthetic 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, as shown in <FIG>. The larger the angle, the greater the force required to open (expand) the frame. 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 up to about <NUM> degrees 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 prosthetic 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>. 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 prosthetic valve construction, portions of the leaflets can protrude longitudinally beyond the outflow end of the frame when the prosthetic 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 prosthetic valve is mounted includes a pushing mechanism or stop member that pushes against or abuts the outflow end of the prosthetic valve (for example, to maintain the position of the crimped prosthetic valve on the delivery catheter), the pushing member or stop member can damage the portions of the exposed leaflets that extend beyond the outflow end of the frame. Another benefit of mounting the leaflets at a location spaced away from the outflow end of the frame is that when the prosthetic valve is crimped on a delivery catheter, the outflow end of the frame <NUM> rather than the leaflets <NUM> is the proximal-most component of the prosthetic valve <NUM>. As such, if the delivery catheter includes a pushing mechanism or stop member that pushes against or abuts the outflow end of the prosthetic valve, the pushing mechanism or stop member contacts the outflow end 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. This allows the frame, when crimped, to assume an overall tapered shape that tapers from a maximum diameter at the outflow end of the prosthetic valve to a minimum diameter at the inflow end of the prosthetic 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 that generally corresponds to the region of the frame covered by the outer skirt <NUM>. In some embodiments, the reduced diameter region 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 prosthetic valve. When the prosthetic valve is deployed, the frame can expand to the generally cylindrical shape shown in <FIG>. In one example, the frame of a <NUM>-mm prosthetic valve, when crimped, had a first diameter of <NUM> French at the outflow end of the prosthetic valve and a second diameter of <NUM> French at the inflow end of the prosthetic valve.

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 prosthetic 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 materials or natural materials (e.g., pericardial tissue) can be used. The thickness of the skirt desirably is less than about <NUM> (about <NUM> mil), and desirably less than about <NUM> (about <NUM> mil), and even more desirably about <NUM> (about <NUM> mil). In particular embodiments, the skirt <NUM> can have a variable thickness, for example, the skirt can be thicker at at least one of 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 inner 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 reinforcing strips <NUM> (which collectively can form a sleeve), for example thin, PET reinforcing strips, 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 Ethibond Excel® PET suture (Johnson & Johnson, New Brunswick, New Jersey). Sutures <NUM> desirably track the curvature of the bottom edge of leaflet structure <NUM>, as described in more detail below.

Known fabric skirts may comprise a weave of warp and weft fibers that extend perpendicularly to each other and with one set of the fibers extending longitudinally between 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 with limited elasticity cannot elongate along with the frame and therefore tends to deform the struts of the frame and to prevent 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 (or <NUM>-<NUM> degrees or <NUM>-<NUM> degrees) relative to the upper and lower edges <NUM>, <NUM>. For example, 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 <NUM> can be diagonally cut (cut on a bias) from a vertically woven fabric (where the fibers extend perpendicularly 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 general shape of the skirt is that of a rhomboid or parallelogram.

<FIG> show the inner skirt <NUM> after opposing short 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 short edges <NUM>, <NUM>. The upper edge portion of the inner skirt <NUM> can be formed with a plurality of projections <NUM> that define an undulating shape that generally follows the shape or contour 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 the inner skirt <NUM> can be tightly secured to struts <NUM> with sutures <NUM>. The inner 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 the inner skirt <NUM> to be partially wrapped around struts <NUM> and to reduce stresses in the skirt during the attachment procedure. For example, in the illustrated embodiment, the inner 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 inner skirt <NUM> around struts <NUM> in this manner provides for a stronger and more durable attachment of the skirt to the frame. The inner skirt <NUM> can also be secured to the first, second, and/or third rows of struts <NUM>, <NUM>, and <NUM>, respectively, with sutures <NUM>.

Due to the angled 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, the inner skirt <NUM> can elongate in the axial direction along with the frame and therefore provide 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 on crimping (e.g., 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 prosthetic 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 inner skirt <NUM> formed from <NUM>-denier yarn, the yarn density can be about <NUM>% to about <NUM>% lower than in a typical PET skirt. In some examples, the yarn spacing of the inner skirt <NUM> can be from about <NUM> yarns per cm (about <NUM> yarns per inch) to about <NUM> yarns per cm (about <NUM> yarns per inch), such as about <NUM> yarns per cm (about <NUM> yarns per inch), whereas in a typical PET skirt the yarn spacing can be from about <NUM> yarns per cm (about <NUM> yarns per inch) to about <NUM> yarns per cm (about <NUM> yarns per inch). The oblique edges <NUM>, <NUM> promote a uniform and even distribution of the fabric material along inner circumference of the frame during crimping so as to reduce or 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. Compared to the construction of a typical skirt (fibers running perpendicularly to the upper and lower edges of the skirt), the construction of the inner 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 prosthetic valve. The warp and weft fibers can run perpendicularly 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. This configuration can avoid stress concentrations at the suture line <NUM>, which attaches the lower edges of the leaflets to the inner skirt <NUM>.

As noted above, the leaflet structure <NUM> in the illustrated embodiment includes three flexible leaflets <NUM> (although a greater or a smaller number of leaflets can be used). Additional information regarding the leaflets, as well as additional information regarding skirt material, can be found, for example, in <CIT>.

The leaflets <NUM> can be secured to one another at their adjacent sides to form commissures <NUM> of the leaflet structure (<FIG>). A plurality of flexible connectors <NUM> (one of which is shown in <FIG>) can be used to interconnect pairs of adj acent sides of the leaflets and to mount the leaflets to the commissure window frame portions <NUM> (<FIG>). <FIG> shows the adjacent sides of two leaflets <NUM> interconnected by a flexible connector <NUM>. Three leaflets <NUM> can be secured to each other side-to-side using three flexible connectors <NUM>, as shown in <FIG>. Additional information regarding connecting the leaflets to each other, as well as connecting the leaflets to the frame, can be found, for example, in <CIT>.

As noted above, the inner skirt <NUM> can be used to assist in suturing the leaflet structure <NUM> to the frame. The inner skirt <NUM> can have an undulating temporary marking suture to guide the attachment of the lower edges of each leaflet <NUM>. The inner 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 desirably are not attached to the inner skirt <NUM>. This allows the inner 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. 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> shows one specific approach for securing the commissure portions <NUM> of the leaflet structure <NUM> to the commissure window frame portions <NUM> of the frame. The flexible connector <NUM> (<FIG>) securing two adjacent sides of two leaflets is folded widthwise and the upper tab portions <NUM> are folded downwardly against the flexible connector. 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, the commissure tab assembly is inserted through the commissure window <NUM> of a corresponding window frame portion <NUM>, and the folds outside of the window frame portion <NUM> can be sutured to portions <NUM>.

<FIG> also shows that the folded down upper tab portions <NUM> can form a double layer of leaflet material at the commissures. The inner portions <NUM> of the upper tab portions <NUM> are positioned flat against 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 prosthetic valve during operation within the body, as opposed to articulating about or proximal to 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 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 prosthetic 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 the longitudinal axis when the balloon catheter is inflated during expansion of the prosthetic valve, which can relieve some of the pressure on the commissures caused by the balloon, reducing potential damage to the commissures 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 inner skirt <NUM> along suture line <NUM> using, for example, Ethibond Excel® PET thread. The sutures can be in-and-out sutures extending through each leaflet <NUM>, the inner skirt <NUM>, and each reinforcing strip <NUM>. Each leaflet <NUM> and respective reinforcing strip <NUM> can be sewn separately to the inner skirt <NUM>. In this manner, the lower edges of the leaflets are secured to the frame <NUM> via the inner 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 inner skirt <NUM> while looping around the edges of the reinforcing strips <NUM> and leaflets <NUM>. The blanket sutures <NUM> can be formed from PTFE suture material. <FIG> shows a side view of the frame <NUM>, leaflet structure <NUM> and the inner skirt <NUM> after securing the leaflet structure <NUM> and the inner skirt <NUM> to the frame <NUM> and the leaflet structure <NUM> to the inner skirt <NUM>.

<FIG> is a flattened view of the outer skirt <NUM> prior to its attachment to the frame <NUM>, showing the outer surface of the skirt. <FIG> is a flattened view of the outer skirt <NUM> prior to its attachment to the frame <NUM>, showing the inner surface of the skirt. <FIG> is a perspective view of the outer skirt prior to its attachment to the frame <NUM>. The outer skirt <NUM> can be laser cut or otherwise formed from a strong, durable material such as PET or various other suitable synthetic or natural materials configured to restrict and/or prevent blood-flow therethrough. The outer skirt <NUM> can comprise a substantially straight lower (inflow or upstream) edge portion <NUM> and an upper (outflow or downstream) edge portion <NUM> defining a plurality of alternating projections <NUM> and notches <NUM>, or castellations, that generally follow the shape of a row of struts of the frame. The lower and upper edge portions <NUM>, <NUM> can have other shapes in alternative embodiments. For example, in one implementation, the lower edge portion <NUM> can be formed with a plurality of projections generally conforming to the shape of a row of struts of the frame <NUM>, while the upper edge portion <NUM> can be straight.

In particular embodiments, the outer skirt <NUM> can comprise at least one soft, plush surface <NUM> oriented radially outward so as to cushion and seal against native tissues surrounding the prosthetic valve. In certain examples, the outer skirt <NUM> can be made from any of a variety of woven, knitted, or crocheted fabrics wherein the surface <NUM> is the surface of a plush nap or pile of the fabric. Exemplary fabrics having a pile include velour, velvet, velveteen, corduroy, terry cloth, fleece, etc. As best shown in <FIG>, the outer skirt can have a base layer <NUM> (a first layer) from which a pile layer <NUM> (a second layer) extends. The base layer <NUM> can comprise warp and weft yarns woven or knitted into a mesh-like structure. For example, in a representative configuration, the yarns of the base layer <NUM> can be flat yarns and can have a denier range of from about <NUM> dtex to about <NUM> dtex, and can be knitted with a density of from about <NUM> to about <NUM> wales per inch and from about <NUM> to about <NUM> courses per inch. The yarns can be made from, for example, biocompatible thermoplastic polymers such as PET, PTFE (polytetrafluoroethylene), Nylon, etc., or any other suitable natural or synthetic fibers.

The pile layer <NUM> can comprise pile yarns <NUM> woven or knitted into loops. In certain configurations, the pile yarns <NUM> can be the warp yarns or the weft yarns of the base layer <NUM> woven or knitted to form the loops. The pile yarns <NUM> can also be separate yarns incorporated into the base layer, depending upon the particular characteristics desired. In a representative configuration, the pile yarns <NUM> can be flat yarns and can have a denier range of from about <NUM> dtex to about <NUM> dtex, and can be knitted with a density of from about <NUM> to about <NUM> wales per inch and from about <NUM> to about <NUM> courses per inch. The pile yarns can be made from, for example, biocompatible thermoplastic polymers such as PET, PTFE, Nylon, etc., or any other suitable natural or synthetic fibers.

In certain embodiments, the loops can be cut such that the pile layer <NUM> is a cut pile in the manner of, for example, a velour fabric. <FIG> and <FIG> illustrate a representative embodiment of the outer skirt <NUM> configured as a velour fabric. In other embodiments, the loops can be left intact to form a looped pile in the manner of, for example, terrycloth. <FIG> illustrates a representative embodiment of the outer skirt <NUM> in which the pile yarns <NUM> are knitted to form loops <NUM>.

The height of the pile yarns <NUM> (e.g., the loops <NUM>) can be the same for all pile yarns across the entire extent of the outer skirt so as to provide an outer skirt having a constant thickness. In alternative embodiments, the height of the pile yarns <NUM> can vary along the height and/or circumference of the outer skirt so as to vary the thickness of the outer skirt along its height and/or circumference, as further described below.

The pile layer <NUM> has a much greater surface area than similarly sized skirts formed from flat or woven materials, and therefore can enhance tissue ingrowth compared to known skirts. Promoting tissue growth into the pile layer <NUM> can decrease perivaluvular leakage, increase retention of the valve at the implant site and contribute to long-term stability of the valve. In some configurations, the surface area of the pile yarns <NUM> can be further increased by using textured yarns having an increased surface area due to, for example, a wavy or undulating structure. In configurations such as the looped pile embodiment of <FIG>, the loop structure and the increased surface area provided by the textured yarn of the loops <NUM> can allow the loops to act as a scaffold for tissue growth into and around the loops of the pile.

The outer skirt embodiments described herein can also contribute to improved compressibility and shape memory properties of the outer skirt over known valve coverings and skirts. For example, the pile layer <NUM> can be compliant such that it compresses under load (e.g., when in contact with tissue, other implants, or the like), and returns to its original size and shape when the load is relieved. This can help to improve sealing between the outer skirt and the tissue of the native annulus, or a surrounding support structure in which the prosthetic valve is deployed. Embodiments of an implantable support structure that is adapted to receive a prosthetic valve and retain it within the native mitral valve are disclosed in co-pending Application No. <CIT>, and Application No. <CIT>. The compressibility provided by the pile layer <NUM> of the outer skirt <NUM> is also beneficial in reducing the crimp profile of the valve. Additionally, the outer skirt <NUM> can prevent the leaflets <NUM> or portions thereof from extending through spaces between the struts of the frame <NUM> as the prosthetic valve is crimped, thereby protecting against damage to the leaflets due to pinching of the leaflets between struts.

In alternative embodiments, the outer skirt <NUM> be made of a non-woven fabric such as felt, or fibers such as non-woven cotton fibers. The outer skirt <NUM> can also be made of porous or spongey materials such as, for example, any of a variety of compliant polymeric foam materials, or woven fabrics, such as woven PET.

Various techniques and configurations can be used to secure the outer skirt <NUM> to the frame <NUM> and/or the inner skirt <NUM>. As best shown in <FIG>, a lower edge portion <NUM> of the inner skirt <NUM> can be wrapped around the inflow end <NUM> of the frame <NUM>, and the lower edge portion <NUM> of the outer skirt <NUM> can be attached to the lower edge portion <NUM> of the inner skirt <NUM> and/or the frame <NUM>, such as with one or more sutures or stitches <NUM> (as best shown in <FIG>) and/or an adhesive. In lieu of or in addition to sutures, the outer skirt <NUM> can be attached to the inner skirt <NUM>, for example, by ultrasonic welding. In the illustrated embodiment, the lower edge portion <NUM> of the outer skirt <NUM> can be free of loops, and the lower edge portion <NUM> of the inner skirt <NUM> can overlap and can be secured to the base layer <NUM> of the outer skirt <NUM>. In other embodiments, the lower edge portion <NUM> of the inner skirt <NUM> can extend over one or more rows of loops <NUM> of the pile layer <NUM> (see <FIG>), as further described below. In other embodiments, the lower edge portion <NUM> of the inner skirt <NUM> can be wrapped around the inflow end of the frame and extend between the outer surface of the frame and the outer skirt <NUM> (i.e., the outer skirt <NUM> is radially outward of the lower edge portion <NUM> of the inner skirt <NUM>).

As shown in <FIG>, each projection <NUM> of the outer skirt <NUM> can be attached to the third row III of struts <NUM> (<FIG>) of the frame <NUM>. The projections <NUM> can, for example, be wrapped over respective struts <NUM> of row III and secured with sutures <NUM>. The outer skirt <NUM> can be further secured to the frame <NUM> by suturing an intermediate portion of the outer skirt (a portion between the lower and upper edge portions) to struts of the frame, such as struts <NUM> of the second row II of struts.

The height of the outer skirt (as measured from the lower edge to the upper edge) can vary in alternative embodiments. For example, in some embodiments, the outer skirt can cover the entire outer surface of the frame <NUM>, with the lower edge portion <NUM> secured to the inflow end of the frame <NUM> and the upper edge portion secured to the outflow end of the frame. In another embodiment, the outer skirt <NUM> can extend from the inflow end of the frame to the second row II of struts <NUM>, or to the fourth row IV of struts <NUM>, or to a location along the frame between two rows of struts. In still other embodiments, the outer skirt <NUM> need not extend all the way to the inflow end of the frame, and instead the inflow end of the outer skirt can secured to another location on the frame, such as to the second row II of struts <NUM>.

The outer skirt <NUM> desirably is sized and shaped relative to the frame such that when the prosthetic valve <NUM> is in its radially expanded state, the outer skirt <NUM> fits snugly (in a tight-fitting manner) against the outer surface of the frame. When the prosthetic valve <NUM> is radially compressed to a compressed state for delivery, the portion of the frame on which the outer skirt is mounted can elongate axially. The outer skirt <NUM> desirably has sufficient elasticity to stretch in the axial direction upon radial compression of the frame so that it does not to prevent full radial compression of the frame or deform the struts during the crimping process.

Known skirts that have material slack or folds when the prosthetic valve is expanded to its functional size are difficult to assemble because the material must be adjusted as it is sutured to the frame. In contrast, because the outer skirt <NUM> is sized to fit snugly around the frame in its fully expanded state, the assembly process of securing the skirt to the frame is greatly simplified. During the assembly process, the outer skirt can be placed around the frame with the frame in its fully expanded state and the outer skirt in its final shape and position when the valve is fully functional. In this position, the skirt can then be sutured to the frame and/or the inner skirt. This simplifies the suturing process compared to skirts that are designed to have slack or folds when radially expanded.

As shown in <FIG>, the height of the loops of the pile layer <NUM> can be constant across the entire extent of the outer skirt such that the outer skirt <NUM> has a constant thickness, except along the upper and lower edge portions which can be free of loops to facilitate attachment of the outer skirt to the frame and/or the inner skirt <NUM>. The "height" of the loops is measured in the radial direction when the skirt is mounted on the frame. In another embodiment, as shown in <FIG>, the loops can comprise lower loops 176a along the lower or upstream portion of the skirt that are relatively shorter in height (as represented by a thinner cross-sectional area) than upper loops 176b (as represented by a thicker cross-sectional area) along the upper or downstream portion of the skirt. The skirt <NUM> can further include a group of intermediate loops 176c that gradually increase in height from the lower loops 176a to the upper loops 176b. Thus, in the embodiment of <FIG>, the thickness of outer skirt <NUM> increases from a minimum thickness along the lower portion to a maximum thickness along the upper portion.

<FIG> shows another embodiment in which the loops of the outer skirt comprise lower loops 176d along the lower portion of the skirt that are relatively higher or longer in height than upper loops 176e along the upper portion of the skirt. The skirt <NUM> can further include a group of intermediate loops 176f that gradually decrease in height from the lower loops 176d to the upper loops 176e. Thus, in the embodiment of <FIG>, the thickness of outer skirt <NUM> decreases from a maximum thickness along the lower portion to a minimum thickness along the upper portion.

<FIG> shows another embodiment in which the loops comprise lower loops <NUM>, upper loops <NUM>, and intermediate loops 176i that are relative shorter in height than the lower and upper loops. As shown, the lower loops <NUM> can gradually decrease in height from the lower edge of the skirt toward the intermediate loops 176i, and the upper loops <NUM> can gradually decrease in height from the upper edge of the skirt toward the intermediate loops 176i. Thus, in the embodiment of <FIG>, the thickness of the outer skirt decreases from a maximum thickness along the lower portion to a minimum thickness along the intermediate portion, and then increases from the intermediate portion to the maximum thickness along the upper portion. In the illustrated embodiment, the upper portion of the skirt containing the upper loops <NUM> has the same thickness as the lower portion of the skirt containing the lower loops <NUM>. In other embodiments, the thickness of the upper portion of the skirt containing the upper loops <NUM> can be greater or less than the same thickness of the lower portion of the skirt containing the lower loops <NUM>.

Further, in any of the embodiments described above where the height of the loops vary along the height of the skirt, the height of the loops need not vary gradually from one section of the skirt to another section of the skirt. Thus, an outer skirt can have loops of different heights, wherein the height of the loops change abruptly at locations along the skirt. For example, in the embodiment of <FIG>, the lower portion of the skirt containing the lower loops 176a can extend all the way to the upper portion of the skirt containing the upper loops <NUM> without the intermediate loops 176c forming a transition between the upper and lower portions.

In lieu of or in addition to having loops that vary in height along the height of the skirt, the height of the loops <NUM> (and therefore the thickness of the outer skirt) can vary along the circumference of the outer skirt. For example, the height of the loops can be increased along circumferential sections of the skirt where larger gaps might be expected between the outer skirt and the native annulus, such as circumferential sections of the skirt that are aligned with the commissures of the native valve.

<FIG> show an alternative configuration for mounting the outer skirt <NUM> to the frame <NUM>. In this embodiment, as best shown in <FIG>, the lower edge portion <NUM> of the inner skirt <NUM> is wrapped around the inflow end of the frame and extended over one or more rows of loops along the lower edge portion <NUM> of the outer skirt. The lower edge portion <NUM> of the inner skirt <NUM> can then be secured to the lower edge portion <NUM> of the outer skirt, such as with sutures or stitching <NUM> (<FIG>), an adhesive, and/or welding (e.g., ultrasonic welding). The stitching <NUM> can also extend around selected struts adjacent the inflow end of the frame. The lower edge portion <NUM> of the inner skirt is effective to partially compress the loops of the pile layer <NUM>, which creates a tapered edge at the inflow end of the prosthetic valve. The tapered edge reduces the insertion force required to push the prosthetic valve through an introducer sheath when being inserted into a patient's body. In one specific implementation, the stitching <NUM> secures the lower edge portion <NUM> of the inner skirt to the outer skirt <NUM> at a distance of at least <NUM> from the lowermost edge of the outer skirt. The upper edge portion <NUM> and the intermediate portion of the outer skirt can then be secured to the frame as previously described.

<FIG> show another configuration for mounting the outer skirt <NUM> to the frame <NUM>. In this embodiment, the outer skirt <NUM> is initially placed in a tubular configuration with the base layer <NUM> facing outwardly and the lower edge portion <NUM> (which can be free of loops <NUM>) can be placed between the inner surface of the frame <NUM> and the lower edge portion <NUM> of the inner skirt <NUM>, as depicted in <FIG>. The lower edge portions of the outer skirt and the inner skirt can be secured to each other, such as with stitches, an adhesive, and/or welding (e.g., ultrasonic welding). In one implementation, the lower edge portions of the outer skirt and the inner skirt are secured to each other with in-and-out stitches and locking stitches. The outer skirt <NUM> is then inverted and pulled upwardly around the outer surface of the frame <NUM> such that the base layer <NUM> is placed against the outer surface of the frame and the pile layer <NUM> faces outwardly, as depicted in <FIG>. In this assembled configuration, the lower edge portion <NUM> of the outer skirt wraps around the inflow end of the frame and is secured to the inner skirt inside of the frame. The upper edge portion <NUM> and the intermediate portion of the outer skirt can then be secured to the frame as previously described.

The prosthetic valve <NUM> can be configured for and mounted on a suitable delivery apparatus for implantation in a subject. Several catheter-based delivery apparatuses are known; a non-limiting example of a suitable catheter-based delivery apparatus includes that disclosed in <CIT> and <CIT>.

To implant a plastically-expandable prosthetic valve <NUM> within a patient, the prosthetic valve <NUM> including the outer skirt <NUM> can be crimped on an elongated shaft of a delivery apparatus. The prosthetic valve, together with the delivery apparatus, can form a delivery assembly for implanting the prosthetic valve <NUM> in a patient's body. The shaft can comprise an inflatable balloon for expanding the prosthetic valve within the body. With the balloon deflated, the prosthetic valve <NUM> can then be percutaneously delivered to a desired implantation location (e.g., a native aortic valve region). Once the prosthetic valve <NUM> is delivered to the implantation site (e.g., the native aortic valve) inside the body, the prosthetic valve <NUM> can be radially expanded to its functional state by inflating the balloon or equivalent expansion mechanism.

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 prosthetic valve <NUM> and the native annulus. The outer skirt <NUM> therefore cooperates with the inner skirt <NUM> to avoid perivalvular leakage after implantation of the prosthetic valve <NUM>. Additionally, as discussed above, the pile layer of the outer skirt further enhances perivalvular sealing by promoting tissue ingrowth with the surrounding tissue.

Alternatively, a self-expanding prosthetic valve <NUM> can be crimped to a radially collapsed configuration and restrained in the collapsed configuration by inserting the prosthetic valve <NUM>, including the outer skirt <NUM>, into a sheath or equivalent mechanism of a delivery catheter. The prosthetic valve <NUM> can then be percutaneously delivered to a desired implantation location. Once inside the body, the prosthetic valve <NUM> can be advanced from the delivery sheath, which allows the prosthetic valve to expand to its functional state.

<FIG> illustrates a sealing member <NUM> for a prosthetic valve, according to another embodiment. The sealing member <NUM> in the illustrated embodiment is formed from a spacer fabric. The sealing member <NUM> can be positioned around the outer surface of the frame <NUM> of a prosthetic valve (in place of the outer skirt <NUM>) and secured to the inner skirt <NUM> and/or the frame using stitching, an adhesive, and/or welding (e.g., ultrasonic welding).

As best shown in <FIG>, the spacer fabric can comprise a first, inner layer <NUM>, a second, outer layer <NUM>, and an intermediate spacer layer <NUM> extending between the first and second layers to create a three-dimensional fabric. The first and second layers <NUM>, <NUM> can be woven fabric or mesh layers. In certain configurations, one or more of the first and second layers <NUM>, <NUM> can be woven such that they define a plurality of openings <NUM>. In some examples, openings such as the openings <NUM> can promote tissue growth into the sealing member <NUM>. In other embodiments, the layers <NUM>, <NUM> need not define openings, but can be porous, as desired.

The spacer layer <NUM> can comprise a plurality of pile yarns <NUM>. The pile yarns <NUM> can be, for example, monofilament yarns arranged to form a scaffold-like structure between the first and second layers <NUM>, <NUM>. For example, <FIG> illustrate an embodiment in which the pile yarns <NUM> extend between the first and second layers <NUM>, <NUM> in a sinusoidal or looping pattern.

In certain examples, the pile yarns <NUM> can have a rigidity that is greater than the rigidity of the fabric of the first and second layers <NUM>, <NUM> such that the pile yarns <NUM> can extend between the first and second layers <NUM>, <NUM> without collapsing under the weight of the second layer <NUM>. The pile yarns <NUM> can also be sufficiently resilient such that the pile yarns can bend or give when subjected to a load, allowing the fabric to compress, and return to their non-deflected state when the load is removed. For example, when the prosthetic valve is radially compressed for delivery into a patient's body and placed in a delivery sheath of a delivery apparatus or advanced through an introducer sheath, the pile yarns <NUM> can compress to reduce the overall crimp profile of the prosthetic valve, and then return to their non-deflected state when deployed from the delivery sheath or the introducer sheath, as the case may be.

The spacer fabric can be warp-knitted, or weft-knitted, as desired. Some configurations of the spacer cloth can be made on a double-bar knitting machine. In a representative example, the yarns of the first and second layers <NUM>, <NUM> can have a denier range of from about <NUM> dtex to about <NUM> dtex, and the yarns of the monofilament pile yarns <NUM> can have a denier range of from about <NUM> mil to about <NUM> mil. The pile yarns <NUM> can have a knitting density of from about <NUM> to about <NUM> wales per inch, and from about <NUM> to about <NUM> courses per inch. Additionally, in some configurations (e.g., warp-knitted spacer fabrics) materials with different flexibility properties may be incorporated into the spacer cloth to improve the overall flexibility of the spacer cloth.

<FIG> shows an outer sealing member <NUM>' mounted on the outside of the frame <NUM> of a prosthetic heart valve <NUM>, according to another embodiment. <FIG> shows the base layer <NUM> of the sealing member <NUM>' in a flattened configuration. <FIG> shows the pile layer <NUM> of the sealing member <NUM>' in a flattened configuration. The outer sealing member <NUM>' is similar to the sealing member <NUM> of <FIG> and <FIG>, except that the height (Hi) of the base layer <NUM> is greater than the height (H<NUM>) of the pile layer <NUM>. Like the previously described embodiments, the sealing member <NUM>' desirably is sized and shaped relative to the frame <NUM> such that when the prosthetic valve is in its radially expanded state, both layers <NUM>, <NUM> of the sealing member <NUM> fit snugly (in a tight-fitting manner) around the outer surface of the frame.

In the illustrated configuration, the base layer <NUM> extends axially from the inlet end of the frame <NUM> to the third row III of struts <NUM> of the frame <NUM>. The upstream and downstream edges of the base layer <NUM> can be sutured to the struts <NUM> of the first row I and to the struts <NUM> of the third row III with sutures <NUM> and <NUM>, respectively, as previously described. The pile layer <NUM> in the illustrated configuration extends from the inlet end of the frame <NUM> to a plane that intersects the frame at the nodes formed at the intersection of the upper ends of struts <NUM> of the second row II and the lower ends of struts <NUM> of the third row III, wherein the plane is perpendicular to the central axis of the frame.

The pile layer <NUM> can be separately formed from and subsequently attached to the base layer <NUM>, such as with sutures, an adhesive, and/or welding. Alternatively, the pile layer <NUM> can be formed from yarns or fibers woven into the base layer <NUM>. The pile layer <NUM> can have any of the configurations shown in <FIG>.

In particular embodiments, the height Hi of the base layer <NUM> can be about <NUM> to about <NUM> or about <NUM> to about <NUM>, with about <NUM> being a specific example. The height H<NUM> of the pile layer <NUM> can be at least <NUM> less than Hi, at least <NUM> less than H<NUM>, at least <NUM> less than H<NUM>, at least <NUM> less than H<NUM>, at least <NUM> less than Hi, at least <NUM> less than Hi, at least <NUM> less than Hi, at least <NUM> than Hi, or at least <NUM> less than Hi. The height of the frame <NUM> in the radially expanded state can be about <NUM> to about <NUM> or about <NUM> to about <NUM>, with about <NUM> being a specific example.

The relatively shorter pile layer <NUM> reduces the crimp profile along the mid-section of the prosthetic valve <NUM> but still provides for enhanced paravalvular sealing along the majority of the landing zone of the prosthetic valve. The base layer <NUM> also provides a sealing function downstream of the downstream edge of the pile layer <NUM>.

<FIG> show an outer sealing member <NUM> for a prosthetic heart valve (e.g., a prosthetic heart valve <NUM>), according to another embodiment. <FIG> are magnified views of portions of the sealing member shown in <FIG>, respectively. The sealing member <NUM> can be mounted on the outside of the frame <NUM> of a prosthetic valve <NUM> in lieu of sealing member <NUM> using, for example, sutures, ultrasonic welding, or any other suitable attachment method. Like the previously described embodiments, the sealing member <NUM> desirably is sized and shaped relative to the frame <NUM> such that when the prosthetic valve is in its radially expanded state, the sealing member <NUM> fits snugly (in a tight-fitting manner) against the outer surface of the frame.

The sealing member <NUM>, like sealing members <NUM>, <NUM>', can be a dual-layer fabric comprising a base layer <NUM> and a pile layer <NUM>. <FIG> shows the outer surface of the sealing member <NUM> defined by the pile layer <NUM>. <FIG> shows the inner surface of the sealing member <NUM> defined by the base layer <NUM>. The base layer <NUM> in the illustrated configuration comprises a mesh weave having circumferentially extending rows or stripes <NUM> of higher-density mesh portions interspersed with rows or stripes <NUM> of lower-density mesh portions.

In particular embodiments, the yarn count of yarns extending in the circumferential direction (side-to-side or horizontally in <FIG> and <FIG>) is greater in the higher-density rows <NUM> than in the lower-density rows <NUM>. In other embodiments, the yarn count of yarns extending in the circumferential direction and the yarn count of yarns extending in the axial direction (vertically in <FIG> and <FIG>) is greater in the higher-density rows <NUM> than in the lower-density rows <NUM>.

The pile layer <NUM> can be formed from yarns woven into the base layer <NUM>. For example, the pile layer <NUM> can comprise a velour weave formed from yarns incorporated in the base layer <NUM>. The pile layer <NUM> can comprise circumferentially extending rows or stripes <NUM> of pile formed at axially-spaced locations along the height of the sealing member <NUM> such that there are axial extending gaps between adjacent rows <NUM>. In this manner, the density of the pile layer varies along the height of the sealing member. In alternative embodiments, the pile layer <NUM> can be formed without gaps between adjacent rows of pile, but the pile layer can comprise circumferentially extending rows or stripes of higher-density pile interspersed with rows or stripes <NUM> of lower-density pile.

In alternative embodiments, the base layer <NUM> can comprise a uniform mesh weave (the density of the weave pattern is uniform) and the pile layer <NUM> has a varying density.

Varying the density of the pile layer <NUM> and/or the base layer <NUM> along the height of the sealing member <NUM> is advantageous in that it facilitates axially elongation of the sealing member <NUM> caused by axial elongation of the frame <NUM> when the prosthetic heart valve is crimped to a radially compressed state for delivery. The varying density also reduces the bulkiness of the sealing member in the radially collapsed state and therefore reduces the overall crimp profile of the prosthetic heart valve.

In alternative embodiments, the density of the sealing member <NUM> can vary along the circumference of the sealing member to reduce the bulkiness of the sealing member in the radially collapsed state. For example, the pile layer <NUM> can comprise a plurality of axially-extending, circumferentially-spaced, rows of pile yarns, or alternatively, alternating axially-extending rows of higher-density pile interspersed with axially-extending rows of lower-density pile. Similarly, the base layer <NUM> can comprise a plurality axially-extending rows of higher-density mesh interspersed with rows of lower-density mesh.

In other embodiments, the sealing member <NUM> can include a base layer <NUM> and/or a pile layer <NUM> that varies in density along the circumference of the sealing member and along the height of the sealing member.

In other embodiments, a sealing member can be knitted, crocheted, or woven to have rows or sections of higher stitch density and rows or sections of lower stitch density without two distinct layers. <FIG>, for example, shows a sealing member <NUM> comprising a fabric having a plurality of axially-extending rows <NUM> of higher-density stitching alternating with axially-extending rows <NUM> of lower-density stitching. The sealing member <NUM> can be formed, for example, by knitting, crocheting, or weaving a single layer fabric having rows <NUM>, <NUM> formed by increasing the stitch density along the rows <NUM> and decreasing the stitch density along the rows <NUM> while the fabric is formed. The sealing member <NUM> can be mounted on the outside of the frame <NUM> of a prosthetic valve <NUM> in lieu of sealing member <NUM> using, for example, sutures, ultrasonic welding, or any other suitable attachment method. Like the previously described embodiments, the sealing member <NUM> desirably is sized and shaped relative to the frame <NUM> such that when the prosthetic valve is in its radially expanded state, the sealing member <NUM> fits snugly (in a tight-fitting manner) against the outer surface of the frame.

The sealing member <NUM> can be resiliently stretchable between a first, substantially relaxed, axially foreshortened configuration (<FIG>) corresponding to a radially expanded state of the prosthetic valve, and a second, axially elongated, or tensioned configuration (<FIG>) corresponding to a radially compressed state of the prosthetic valve. As shown in <FIG>, when the prosthetic valve is radially expanded and the sealing member <NUM> is in the first configuration, the higher-density rows <NUM> extend in an undulating pattern from the lower (upstream edge) to the upper (downstream edge) of the sealing member <NUM>. In the illustrated embodiment, for example, each of the higher-density rows <NUM> comprises a plurality of straight angled sections 406a, 406b arranged end-to-end in a zig-zag or herringbone pattern extending from the lower (upstream edge) to the upper (downstream edge) of the sealing member <NUM>. In alternative embodiments, the rows <NUM> can be sinusoidal-shaped rows having curved longitudinal edges.

When the prosthetic valve is crimped to its radially compressed state, the frame <NUM> elongates, causing the sealing member to stretch in the axial direction, as depicted in <FIG>, to its second configuration. The lower-density rows <NUM> facilitate elongation of the sealing member and permit straightening of the higher-density rows <NUM>. <FIG> depicts the higher-density rows <NUM> as straight sections extending from the inflow edge to the outflow edge of the sealing member. However, it should be understood that the higher-density rows <NUM> need not form perfectly straight rows when the prosthetic valve is in the radially compressed state. Instead, "straightening" of the higher-density rows <NUM> occurs when the angle <NUM> between adjacent angled segments 406a, 406b of each row increases upon axial elongation of the sealing member.

The varying stitch density of the sealing member <NUM> reduces overall bulkiness of the sealing member to minimize the crimp profile of the prosthetic valve. The zig-zag or undulating pattern of the higher-density rows <NUM> in the radially expanded state of the prosthetic valve facilitates stretching of the sealing member in the axial direction upon radial compression of the prosthetic valve and allows the sealing member to return to its prestretched state in which the sealing member fits snugly around the frame upon radial expansion of the prosthetic valve. Additionally, the zig-zag or undulating pattern of the higher-density rows <NUM> in the radially expanded state of the prosthetic valve eliminates any straight flow paths for blood between adjacent rows <NUM> extending along the outer surface of the sealing member from its outflow edge to its inflow edge to facilitate sealing and tissue ingrowth with surrounding tissue.

In alternative embodiments, a sealing member <NUM> can have a plurality of circumferentially extending higher-density rows (like rows <NUM> but extending in the circumferential direction) interspersed with a plurality of circumferentially extending lower-density rows (like rows <NUM> but extending in the circumferential direction). In some embodiments, a sealing member <NUM> can have axially-extending and circumferential-extending higher-density rows interspersed with axially-extending and circumferential-extending lower-density rows.

<FIG>, <FIG> illustrate an outer sealing member <NUM> for a prosthetic heart valve (e.g., a prosthetic heart valve <NUM>), according to another embodiment. The sealing member <NUM> can have a plush exterior surface <NUM>. The sealing member <NUM> can be secured to a frame <NUM> of the prosthetic valve using, for example, sutures, ultrasonic welding, or any other suitable attachment method as previously described herein. For purposes of illustration, enlarged or magnified portions of the sealing member <NUM> are shown in the figures. It should be understood that the overall size and shape of the sealing member <NUM> can be modified as needed to cover the entire outer surface of the frame <NUM> or portion of the outer surface of the frame, as previously described herein.

The sealing member <NUM> can comprise a woven or knitted fabric. The fabric can be resiliently stretchable between a first, natural, or relaxed configuration (<FIG>), and a second, axially elongated, or tensioned configuration (<FIG>). When disposed on the frame <NUM>, the relaxed configuration can correspond to the radially expanded, functional configuration of the prosthetic valve, and the elongated configuration can correspond to the radially collapsed delivery configuration of the prosthetic valve. Thus, with reference to <FIG>, the sealing member <NUM> can have a first length L<NUM> in the axial direction when the prosthetic valve is in the radially expanded configuration, and a second length L<NUM> (<FIG>) in the axial direction that is longer than L<NUM> when the valve is crimped to the delivery configuration, as described in greater detail below.

The fabric can comprise a plurality of circumferentially extending warp yarns <NUM> and a plurality of axially extending weft yarns <NUM>. In some embodiments, the warp yarns <NUM> can have a denier of from about <NUM> D to about <NUM> D, about <NUM> D to about <NUM> D, or about <NUM> D to about <NUM> D. In some embodiments, the warp yarns <NUM> can have a thickness t<NUM> (<FIG>) of from about <NUM> to about <NUM>, about. <NUM> to about <NUM>, or about <NUM> to about <NUM>. In some embodiments, the warp yarns <NUM> can have a thickness t<NUM> of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. In a representative embodiment, the warp yarns <NUM> can have a thickness of about <NUM>.

The weft yarns <NUM> can be texturized yarns comprising a plurality of texturized filaments <NUM>. For example, the filaments <NUM> of the weft yarns <NUM> can be bulked, wherein, for example, the filaments <NUM> are twisted, heat set, and untwisted such that the filaments retain their deformed, twisted shape in the relaxed, non-stretched configuration. The filaments <NUM> can also be texturized by crimping, coiling, etc. When the weft yarns <NUM> are in a relaxed, non-tensioned state, the filaments <NUM> can be loosely packed and can provide compressible volume or bulk to the fabric, as well as a plush surface. In some embodiments, the weft yarns <NUM> can have a denier of from about <NUM> D to about <NUM> D, about <NUM> D to about <NUM> D, about <NUM> D to about <NUM> D, about <NUM> D to about <NUM> D, or about <NUM> D to about <NUM> D. In certain embodiments, the weft yarns <NUM> can have a denier of about <NUM> D. In some embodiments, a filament count of the weft yarns <NUM> can be from <NUM> filaments per yarn to <NUM> filaments per yarn, <NUM> filaments per yarn to <NUM> filaments per yarn, <NUM> filaments per yarn to <NUM> filaments per yarn, or about <NUM> filaments per yarn to <NUM> filaments per yarn. Additionally, although the axially-extending textured yarns <NUM> are referred to as weft yarns in the illustrated configuration, the fabric may also be manufactured such that the axially-extending textured yarns are warp yarns and the circumferentially-extending yarns are weft yarns.

<FIG> illustrate a cross-sectional view of the sealing member in which the weft yarns <NUM> extend into the plane of the page. With reference to <FIG>, the fabric of the sealing member <NUM> can have a thickness t<NUM> of from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> when in a relaxed state and secured to a frame. In some embodiments, the sealing member <NUM> can have a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> as measured in a relaxed state with a weighted drop gauge having a presser foot. In a representative example, the sealing member can have a thickness of about <NUM> when secured to a prosthetic valve frame in the relaxed state. The texturized, loosely packed filaments <NUM> of the weft yarns <NUM> in the relaxed state can also promote tissue growth into the sealing member <NUM>.

When the fabric is in the relaxed state, the textured filaments <NUM> of the weft yarns <NUM> can be widely dispersed such that individual weft yarns are not readily discerned, as depicted in <FIG>. When tensioned in the axial direction, the filaments <NUM> of the weft yarns <NUM> can be drawn together as the weft yarns elongate and the kinks, twists, etc., of the filaments are pulled straight such that the fabric is stretched and the thickness decreases. In certain embodiments, when sufficient tension is applied to the fabric in the axial direction (the weft direction in the illustrated embodiment), such as when the prosthetic valve is crimped onto a shaft of a delivery apparatus, the textured fibers <NUM> can be pulled together such that individual weft yarns <NUM> become discernable, as best shown in <FIG>.

Thus, for example, when fully stretched, the sealing member can have a second thickness t<NUM>, as shown in <FIG> that is less than the thickness t<NUM>. In certain embodiments, the thickness of the tensioned weft yarns <NUM> may be the same or nearly the same as the thickness t<NUM> of the warp yarns <NUM>. Thus, in certain examples, when stretched the fabric can have a thickness t<NUM> that is the same or nearly the same as three times the thickness t<NUM> of the warp yarns <NUM> depending upon, for example, the amount of flattening of the weft yarns <NUM>. Accordingly, in the example above in which the warp yarns <NUM> have a thickness of about <NUM>, the thickness of the sealing member can vary between about <NUM> and about <NUM> as the fabric stretches and relaxes. Stated differently, the thickness of the fabric can vary by <NUM>% or more as the fabric stretches and relaxes.

Additionally, as shown in <FIG>, the warp yarns <NUM> can be spaced apart from each other in the fabric by a distance y<NUM> when the outer covering is in a relaxed state. As shown in <FIG> and <FIG>, when tension is applied to the fabric in the direction perpendicular to the warp yarns <NUM> and parallel to the weft yarns <NUM>, the distance between the warp yarns <NUM> can increase as the weft yarns <NUM> lengthen. In the example illustrated in <FIG>, in which the fabric has been stretched such that the weft yarns <NUM> have lengthened and narrowed to approximately the diameter of the warp yarns <NUM>, the distance between the warp yarns <NUM> can increase to a new distance y<NUM> that is greater than the distance y<NUM>.

In certain embodiments, the distance y<NUM> can be, for example, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. In a representative example, the distance y<NUM> can be about <NUM>. In some embodiments, when the fabric is stretched as in <FIG> and <FIG>, the distance y<NUM> can be about <NUM> to about <NUM>. Thus, in certain embodiments, the length of the sealing member <NUM> in the axial direction can vary by <NUM>% or more between the relaxed length L<NUM> and the fully stretched length (e.g., L<NUM>). The fabric's ability to lengthen in this manner facilitates crimping of the prosthetic valve. Thus, the sealing member <NUM> can be soft and voluminous when the prosthetic valve is expanded to its functional size, and relatively thin when the prosthetic valve is crimped to minimize the overall crimp profile of the prosthetic valve.

It should be understood that the disclosed embodiments can be adapted to deliver and implant prosthetic devices in any of the native annuluses of the heart (e.g., the pulmonary, mitral, and tricuspid annuluses), and can be used with any of various approaches (e.g., retrograde, antegrade, transseptal, transventricular, transatrial, etc.). The disclosed embodiments can also be used to implant prostheses in other lumens of the body. Further, in addition to prosthetic valves, the delivery assembly embodiments described herein can be adapted to deliver and implant various other prosthetic devices such as stents and/or other prosthetic repair devices.

For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved.

As used in this application and in the claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Additionally, the term "includes" means "comprises. " Further, the terms "coupled" and "associated" generally mean electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

As used herein, the term "proximal" refers to a position, direction, or portion of a device that is closer to the user and further away from the implantation site. As used herein, the term "distal" refers to a position, direction, or portion of a device that is further away from the user and closer to the implantation site. Thus, for example, proximal motion of a device is motion of the device toward the user, while distal motion of the device is motion of the device away from the user. The terms "longitudinal" and "axial" refer to an axis extending in the proximal and distal directions, unless otherwise expressly defined.

As used herein, the terms "integrally formed" and "unitary construction" refer to a construction that does not include any welds, fasteners, or other means for securing separately formed pieces of material to each other.

As used herein, operations that occur "simultaneously" or "concurrently" occur generally at the same time as one another, although delays in the occurrence of one operation relative to the other due to, for example, spacing, play or backlash between components in a mechanical linkage such as threads, gears, etc., are expressly within the scope of the above terms, absent specific contrary language.

Claim 1:
A prosthetic heart valve, comprising:
an annular frame (<NUM>) comprising an inflow end and an outflow end and being radially compressible and expandable between a radially compressed configuration and a radially expanded configuration having a cylindrical shape,
wherein the frame (<NUM>) comprises a plurality of rows of angled struts (<NUM>) arranged end-to-end and extending circumferentially, wherein a first, uppermost row of angled struts (<NUM>) and a second row of angled struts (<NUM>) immediately adjacent to the first row of angled struts (<NUM>) along with frame portions (<NUM>) and struts (<NUM>) define an upper row of cells defining openings (<NUM>);
a leaflet structure (<NUM>) positioned within the frame (<NUM>) and secured thereto; and
an outer skirt (<NUM>) mounted outside of the frame (<NUM>) and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient,
wherein the outer skirt (<NUM>) comprises an inflow edge portion (<NUM>) and an outflow edge portion (<NUM>) defining a plurality of alternating projections (<NUM>) and notches (<NUM>) that follow the shape of a row of angled struts (<NUM>, <NUM>, <NUM>, <NUM>) of the frame (<NUM>),
wherein the outer skirt (<NUM>) is sized and shaped relative to the frame (<NUM>) such that when the prosthetic valve (<NUM>) is in its radially expanded state, the outer skirt (<NUM>) fits snugly against the outer surface of the frame (<NUM>), and
an inner skirt (<NUM>) mounted on an inner surface of the frame (<NUM>), the inner skirt (<NUM>) having an inflow edge portion that is secured to an inflow edge portion of the outer skirt (<NUM>),
wherein an outflow edge portion of the inner skirt (<NUM>) is secured to the second row of angled struts such that the openings (<NUM>) of the upper row of cells are not covered by the inner skirt (<NUM>).