SEALING MEMBER WITH PROSTHETIC HEART VALVE.

Abstract

A prosthetic heart valve includes an annular frame having an inflow end and an outflow end, and which is radially compressible and expandable between a radially compressed and a radially expanded configuration. The prosthetic heart valve further includes a blade structure positioned within and secured to the frame, and an external sealing member mounted on the outside of the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within a patient's native heart valve ring. The sealing member may include a mesh layer and a hair layer comprising a plurality of hair strands extending outward from the mesh layer.

Description

SEALING MEMBER WITH PROSTHETIC HEART VALVE Field of Invention This description relates to 5 expandable and implantable prosthetic devices and to methods and apparatus for these prosthetic devices. Background of the Invention The human heart can suffer from various valvular diseases. These valvular diseases can result in significant heart dysfunction and eventually require replacement of the native valve with an artificial valve. Numerous artificial valves are known, as are many methods for implanting them in humans. Due to the drawbacks associated with conventional open-heart surgery, percutaneous and minimally invasive surgical approaches are gaining intense attention. In one technique, a prosthetic valve is configured for implantation in a much less invasive procedure via catheterization. For example, collapsible transcatheter prosthetic heart valves can be corrugated to a compressed state and percutaneously introduced in this compressed state over a catheter and expanded to a functional size in the desired position by inflating a balloon. I laughed. 302828 or by using a self-expanding frame or endoprosthesis. A prosthetic valve for use in this procedure may include a radially expandable, foldable frame to which prosthetic valve cups can be attached. For example, U.S. Patents Nos. 6,730,118; 7,393,360; 7,510,575 and 7,993,3.94 describe foldable transcatheter cardiac valves (THV). One challenge with catheter-implanted prosthetic valves is the corrugation process, given that a prosthetic valve has a profile suitable for percutaneous delivery to a patient. Another challenge is controlling valve leakage around the valve, which can occur for a period of time after initial implantation. Valve leakage has been a known problem since replacement valves were first introduced. The earliest prosthetic heart valves, those that were surgically implanted, included a circumferential suture ring that was adapted to extend into the spaces in the tissue surrounding the implanted prosthesis to prevent valve leakage. For example, U.S. Patent No. 2.5 3,365,728 describes a prosthetic heart valve for surgical implantation that includes a rubber cushion ring that conforms to tissue irregularities to form an effective seal between the valve and the surrounding tissue. From this, vascular endoprostheses or endoprosthesis grafts have been developed for implantation by non-surgical catheterization techniques. These endoprostheses include a fabric covering that allows the endoprosthesis to be used to isolate and reinforce the wall of a blood vessel from the vessel lumen. These fabric coverings serve essentially the same purpose on the endoprosthesis as sealing rings do on surgical heart valves—to reduce the risk of blood leakage between the prosthesis and the surrounding tissue. Multiple graft designs have been developed that further enhance the external seal to prevent blood from flowing between the graft and the surrounding cardiovascular tissue.For example, U.S. Patent No. 6,015,431 to Thornton describes a seal secured to the outer surface of an endoprosthesis that is adapted to obstruct leakage flow externally around the endoprosthesis wall between the outer surface and the endoluminal wall when the endoprosthesis is deployed, by conforming to the regular surface of the surrounding tissue. U.S. Patent Publication 2003 / 0236567 to Elliot similarly describes a tubular prosthesis having an endoprosthesis and one or more fabric skirts for sealing against endoleaks. U.S. Patent Publication 2004 / 0082989 to Cook et al. also recognizes the potential for endoleaks and describes an endoprosthesis graft having a cuff portion with an external sealing strip that stretches around the endoprosthesis body to prevent leakage.The fist portion can fold over itself to create a receptacle that collects any blood that passes around the front edge of the graft to prevent endoleakage. Building on this technology, the first permanent bioprosthetic heart valve was implanted using transcatheter techniques in the late 1980s. U.S. Patent No. 5,411,552 for 15 Ande raen describes a heart valve (HV) comprising a valve mounted within a foldable and expandable endoprosthesis structure. Certain modalities have additional graft material used along the external and internal surfaces of the HV. Similar to endoprosthesis grafts, the proposed covers for use with HVs have been designed to conform to the surrounding tissue surface to prevent paravalvular leakage. Similar to endoprostheses, cuffs or other external seals have been used over THVs. U.S. Patent No. 5,855,601 for B. Essler describes a THV. - 5 self-expanding which has a cuff portion that extends along the outside of the endoprosthesis. Before folding the endoprosthesis for delivery, the outer seal collapses to form folds, then expands with the endoprosthesis to provide a seal between the THV and the surrounding tissue. Subsequently, a different THV design was described by Pavc.nik in U.S. patent application 2001 / 0039450. Pavcnik's enhanced sealing structure consists of corner fins or receptacles secured to the endoprosthesis at the edges of each fin or receptacle and positioned at different locations around the prosthesis. The corner fin is designed to retain retrograde blood flow to provide a better seal between the THV and the vessel wall, as well as to provide an improved substrate for ingrown native tissue. Thus, the fabric and other materials used to cover and seal both the internal and external surfaces of THVs and other endovascular prostheses—such as endoprostheses and endoprosthesis grafts—are well known. These coverings can be made from low-porosity woven fabric materials, as described, for example, in U.S. Patent No. 5,957,949 for Leonhardt et al. describe a valve endoprosthesis that has an outer covering that can adapt to the surrounding living tissue before implantation to help prevent blood leakage. Several more recent THV designs include a 5 THV with an outer cover. US Patent No. U.S. Patent No. 7,510,575 to Spenser describes a THV having a cuff portion wrapped around the outer surface of the support endoprosthesis at the inlet. The cuff portion is rolled over the rim of the frame so that it provides a sleeve-like portion at the inlet to form a cuff over the inlet that helps prevent blood leakage. U.S. Patent No. 8,002,825 to Le tac and Cribier describes an inner cover that extends from the base of the valve to the lower end of the endoprosthesis and then upward to the outer wall of the endoprosthesis so that it forms an outer cover. The one-piece cover can be made of any of the materials described for fabricating the valve structure, which include fabric (for example, Dacron), biological material (for example, pericardium), or other synthetic materials (for example, polyethylene). Although the covers used on the external surface of an endovascular prosthesis to prevent leakage 25 for valve are well known, there remains a need for improved covers that provide improved sealing but also provide a small profile suitable for percutaneous delivery to a patient. Summary of the Invention The various configurations of a radially expandable, foldable prosthetic valve are described herein, including an improved outer skirt to reduce perivalvular leakage, as well as related methods and devices incorporating these prosthetic valves. In several configurations, the prosthetic valves described are configured as replacement heart valves for implantation in a subject. In a representative embodiment, a prosthetic heart valve comprises an annular frame having an inflow end and an outflow end, and being radially compressible and expandable between a radially compressed and a radially expanded configuration. The prosthetic heart valve further includes a box structure positioned within and secured to the frame, and an external sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within the annulus of a patient's native heart valve. The sealing member may comprise a mesh layer and a hair layer comprising a plurality of hair strands extending outward from the mesh layer. In some versions, the mesh layer comprises a knitted fabric. In some forms, the strands of hair are distributed to form a set of hairs with loops. In some forms, the strands of hair are cut to form a set of cut hairs. In some models, the height of the .10 hair threads varies along a height and / or circumference of the outer skirt. In some forms, the hair threads comprise a first group of threads along an upstream portion of the outer skirt and a second group of threads along a downstream portion of the outer skirt, wherein the threads of the first group have a height that is less than a height of the threads of the second group. In some forms, the .20 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 in the first group have a height that is greater than a height of the yarns in the second group. In some forms, the hair threads comprise a first group of threads along an upstream portion of the outer skirt, a second group of threads along a downstream portion of the outer skirt, and a third group of threads between the first and second groups of threads, wherein the threads of the first and second groups have a height that is greater than the height of the threads of the third group. In some embodiments, the 1:0 prosthetic heart valve further comprises an inner skirt mounted on an inner surface of the frame; the inner skirt has an inlet flow end portion that is secured to an inlet flow end portion of the outer sealing member. In some embodiments, the inlet flow end portion of the inner skirt is wrapped around an inlet flow end of the frame and overlaps the inlet flow 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 positioned radially outside the hair layer. In some embodiments, the outer sealing member is configured to stretch axially when the frame is compressed radially to the radially compressed state. In some forms, the mesh layer comprises warp and weft yarns woven with the warp yarns, and the pile layer comprises the warp or 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 hair layer comprises a separate hair layer that is knitted to the woven fabric layer. In some forms, the mesh layer has a first height that extends axially along the frame and the hair layer comprises a second height that extends axially along the frame, wherein the first height is greater than the second height. In some models, the mesh layer extends closer to the output flow end of the frame compared to the hair layer. In another representative embodiment, 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. The prosthetic heart valve further comprises a blade structure positioned within and secured to the frame, and an external sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within a patient's native heart valve ring. The sealing member may comprise a fabric having a variable thickness. In some modalities, the thickness of the 10 fabric layer varies along with the height and / or circumference of the outer sealing member. In some versions, the fabric comprises a plush fabric. In some forms, the fabric comprises a plurality of pile threads and the height of the pile threads varies along with the height and / or circumference of the outer f a1don. In some forms, the hair threads comprise a first group of threads along a portion upstream of the outer skirt and a second group of threads along a portion downstream of the outer skirt, wherein the threads of the first group have a height that is less than the height of the threads of the second group. In some forms, the hair threads comprise a first group of threads along an upstream portion of the outer skirt and a second group of threads along a downstream portion of the outer skirt, wherein the threads of the first group have a height that is greater than a height of the threads of the second group. In some forms, the hair threads comprise a first group of threads along an upstream portion of the outer skirt, a second group of threads along a downstream portion of the outer skirt, and a third group of threads between the first and second groups of threads, wherein the threads of the first and second groups have a height that is greater than the height of the threads of the third group. In another representative embodiment, a prosthetic heart valve comprises an annular frame having an inflow end and an outflow end, and being radially compressible and expandable between a radially compressed and a radially expanded configuration. The prosthetic heart valve further comprises a blade structure positioned within and secured to the frame, and an external sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within the annulus of a patient's native heart valve. The sealing member may comprise a pile fabric comprising a plurality of pile threads, wherein the density of the pile threads varies in an axial and / or circumferential direction along the sealing member. In some forms, the hair strands are distributed in rows that extend circumferentially, and the density of the hair strands varies from row to row. In some forms, the hair strands are distributed in rows that extend axially from one row of hair strands and the density of the hair strands varies from row to row. In some embodiments, the sealing member comprises a mesh layer and a pile layer comprising the pile fibers. In some embodiments, the crimp density of the mesh layer varies in an axial and / or circumferential direction along the sealing member. In some embodiments, the mesh layer comprises one or more rows of mesh portions of higher density and one or more rows of mesh portions of lower density. One or more rows of mesh portions of higher density and one or more rows of mesh portions of lower density may be circumferentially extending and / or axially extending. In another representative embodiment, a prosthetic heart valve comprises an annular frame comprising an inflow end and an outflow end, and which is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a blade structure positioned within and secured to the frame, and an external sealing member mounted outside the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a patient's native heart valve ring. The sealing member comprises a textile formed from a plurality of fibers distributed in a plurality of axially extending rows of higher stitch density interposed 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 shortened configuration when the frame is in the radially expanded configuration, and a second axially lengthened configuration when the frame is in the radially compressed configuration. In some configurations, each of the higher stitch density rows may extend in a wavy pattern when the sealing member is in the axially shortened configuration. When the sealing member is in the axially lengthened configuration, the higher stitch density rows move from the wavy pattern to a straight pattern. In another representative embodiment, a prosthetic heart valve comprises an annular frame comprising an inflow end and an outflow end, and which is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further comprises a blade structure positioned within and secured to the frame, an external sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within a patient's native heart valve ring. 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 compressed radially from the...The filaments that extend axially 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 forms, the axially extending filaments are shaped by heat 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 a less deformed or twisted state. Brief Description of the Figures Figure 1 is a perspective view of a prosthetic heart valve, according to one modality. Figure 2 is an enlarged .15 perspective view of the inflow end portion of the prosthetic heart valve in Figure 1. Figure 3 is a cross-sectional view of the prosthetic heart valve in Figure 1, showing the joining of the outer skirt to the inner skirt and frame. Figures 4 to 10 show an exemplary frame of the prosthetic heart valve of Figure 1. Figures 11 to 12 show an exemplary inner skirt of the prosthetic heart valve of Figure 1. Figures 13 to 15 show the assembly of the inner skirt of Figure 1.1 with the frame of Figure 1.1. Figures 16 to 17 show the assembly of an exemplary box-shaped structure. Figure 18 shows the assembly of the commissure portions of the box structure with window frame portions of the frame. Figures 19 to 20 show the assembly of the box structure with the inner skirt along the lower edge of the boxes. Figures 21 to 23 are different views of an exemplary outer skirt of the prosthetic heart valve of Figure 1. Figures 24 to 26 are cross-sectional views similar to those in Figure 3 but showing different types of outer skirt. Figures 27 to 28 show an alternative way of securing an outer skirt to an inner skirt and / or frame of a prosthetic heart valve. Figures 29 to 32 show another way of securing an outer skirt to an inner skirt and / or frame of a prosthetic heart valve. Figures 33 to 35 show another modality of an external sealing member for a prosthetic heart valve Figure 36 shows another modality of an external sealing member, which is shown mounted on the frame of a prosthetic heart valve. Figure 37 shows a flattened view of a 5-layer woven mesh of the sealing member of Figure 36. Figure 38 is a flattened view of a hair layer of the sealing member of Figure 36. Figure 39 is a flattened view of the outer surface of an outer sealing member for a prosthetic heart valve, according to another modality. Figure 39A is an enlarged view of a portion of the sealing member of Figure 39. Figure 40 is a flattened view of the inner surface of the sealing member of Figure 39. Figure 40I is an enlarged view of a portion of the sealing member of Figure 40. Figure 41 is a flattened view of an outer sealing member for a prosthetic heart valve shown in a relaxed state when the prosthetic heart valve 20 is expanded radially to its functional size, according to another modality. Figure 42 is a flattened view of the outer sealing member of Figure 41 shown in a tensioned, axially elongated state when the prosthetic heart valve 25 is in a radially compressed state for placement. Figure 43A is an enlarged view of a portion of another modality of an external sealing member for a prosthetic heart valve, wherein the sealing member is shown in a relaxed state when the prosthetic heart valve is expanded radially to its functional size. Figure 43B is an enlarged view of the sealing member of Figure 43A shown in an axially elongated tensioned state when the prosthetic 1'0 heart valve is in a radially compressed state for placement. Figure 44A is a cross-sectional view of the sealing member fabric of Figure 43A in a relaxed state. Figure 44B is a cross-sectional view of the fabric of the sealing member of Figure 43B in a tensioned state. Detailed Description of the Invention Figure 1 shows a prosthetic heart valve 2 0 10, according to one modality. The prosthetic valve illustrated is adapted to be implanted in the native aortic annulus, although in other modalities it can be adapted to be implanted in other native annuluses of the heart (e.g., the pulmonic, mitral, and tricuspid valves). The prosthetic valve may also be adapted for implantation in other organs or tubular passages in the body. The prosthetic valve 10 may have four main components: an endoprosthesis or frame 12, a valve structure 14, an inner skirt 16, and a perivalvular outer sealing member 5 or outer skirt 18. The prosthetic valve 10 may have an inflow end portion 1.5, an intermediate portion 1.7, and an outflow end portion 19. The valve structure 14 may comprise three leaflets (Figure 17) that collectively form a leaflet structure, which may be arranged to fold into a tricuspid arrangement. The lower edge of the leaflet structure 14 desirably has a curved, scalloped shape (suture line 154 shown in Figure 20, which follows the scalloped shape of the leaflet structure). By shaping the leaflets with this scalloped geometry, stresses on the leaflets are reduced, which in turn improves the durability of the prosthetic valve. Furthermore, due to the scalloped shape, the folds and curls in the mid-portion of each leaflet (the central region of each leaflet), which can lead to early calcification in these areas, can be eliminated or at least miniaturized.The scalloped geometry also reduces the amount of tissue material used to form the leaflet structure, thereby allowing for a smaller, even more corrugated profile at the inlet flow end of the prosthetic valve. The leaflets can be formed from pericardial tissue (e.g., bovine pericardial tissue), biocompatible synthetic materials, or various other suitable natural or synthetic materials as known in the field and as described in U.S. Patent No. 6,730,118. The bare frame 12 is shown in Figure 4. The frame 12 may be formed with a plurality of circumferentially spaced grooves, or commissure windows 20 (three are illustrated in the embodiment), which are adapted for mounting the commissures of the valve structure 14 to the frame, as described in more detail below. The frame 12 may 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 is known in the field. When constructed of a plastically expandable material, the frame 12 (and therefore the prosthetic valve 10) may be corrugated into a radially folded configuration over a placement catheter and then expanded within a patient by an inflatable balloon or equivalent expansion mechanism.When constructed from a self-expanding material, the frame 12 (and therefore the prosthetic valve 10) can be corrugated into a radially collapsed configuration and retained in this configuration by insertion into a sheath or equivalent placement catheter mechanism. Once 5 inside the body, the prosthetic valve can be advanced from the placement sheath, allowing it to expand to its functional size. Suitable plastically expandable materials that can be used to form the frame 12 include, without limitation, stainless steel, biocompatible high-strength alloys (e.g., cobalt-chromium alloys or a nickel-cobalt-chromium alloy), polymers, or combinations thereof. In particular embodiments, the frame 12 is made from a nickel-cobalt-chromium-molybdenum alloy, such as the MP35NMR alloy (SPS Technologies, Jenkintown, Pennsylvania), which is equivalent to UNS R30035 alloy (covered by ASTM F562-Q2). The MPSSN / UNS R3003.5 alloy comprises 35% nickel, 3.5% cobalt, 20% chromium, and 10% molybdenum by weight. It has been found that the use... Using MP35JF® alloy to form frame 12 provides superior structural results compared to stainless steel.In particular, when MP35NMR alloy is used as the frame material, less material is required to achieve equal or better performance in radial and compressive strength, toughness, fatigue resistance, and corrosion resistance. Furthermore, because less material is required, the corrugated profile of the frame can be reduced, resulting in a lower-profile prosthetic valve assembly for percutaneous placement at the treatment site in the body. With reference to Figures 4 and 5, the frame 12 in the illustrated embodiment comprises a lower first row 1 of angled endoprostheses 22 distributed end-to-end and extending circumferentially at the inflow end of the frame; a second row II of circumferentially extending angled endoprostheses 24; a third row III of circumferentially extending angled endoprostheses 26; a fourth row IV of circumferentially extending angled endoprostheses 28; and a fifth row V of circumferentially extending angled endoprostheses 32 at the outflow end of the frame. A plurality of substantially straight axially extending endoprostheses 34 can be used to interconnect the endoprostheses 22 of the first row 1 with the endoprostheses 24 of the second row II.The fifth row V of angled endoprostheses 32 are connected to the fourth row IV of angled endoprostheses 28 by a plurality of axially extending window frame portions (which define the commissure windows 20) and a plurality of axially extending endoprostheses 31. Each axial endoprosthesis 31 and each frame portion 30 extends from a location defined by the convergence 5 of the inner ends of the two angled endoprostheses to another location defined by the convergence of the upper ends of the two angled endoprostheses 28. Figures 6, 7, 8, Θ, and 10 are enlarged views of the frame portions 12 identified by the letters A, B, C, D, and E, respectively, in Figure 5. Each commissure window frame portion 30 supports a respective commissure of the leaf structure 14. As can be seen, each frame portion 30 is secured at its upper and lower ends to the adjacent rows 15 of endoprosthesis to provide a robust configuration that increases the fatigue strength under cyclic loading of the prosthetic valve compared to known cantilever endoprostheses supporting the leaf structure commissures. This configuration 20 allows for a reduction in frame wall thickness to obtain a smaller corrugated diameter of the prosthetic valve. In particular modalities, the thickness T of the frame 12 (Figure 4) measured between the inner and outer diameters is approximately 0.48 ± 25 mm or less. The endoprosthesis and frame portions of the frame collectively define a plurality of open frame cells. At the inflow end of frame 12, endoprostheses 22, 24, and 34 define a bottom row of cells that define openings 36. The second, third, and fourth rows of endoprostheses 24, 26, and 28 define two middle rows of cells that define openings 38. The fourth and fifth rows of endoprostheses 28 and 32, along with portions of frame 30 and endoprosthesis 31, define a top row of cells that define openings 40. The openings 41 are relatively large and are sized to allow portions of the sheet structure 14 to protrude or extend into and / or through the openings 40 when frame 12 is corrugated in order to minimize the corrugation profile. As best shown in Figure 7, the lower end of endoprosthesis 31 connects to two endoprostheses 28 at a node or junction 44, and the upper end of endoprosthesis 31 connects to two endoprostheses 32 at a node or junction 46. Endoprosthesis 31 may have a thickness SI that is less than the thickness S2 of the junctions 44 to 46. Junctions 44, 46, together with junction 64, prevent complete closure of the openings 40. The geometry of endoprosthesis 31 and the junctions 4, 46 help create sufficient space in the openings 41 in the collapsed configuration to allow portions of the prosthetic leaflets to protrude or bulge outward through the openings. This allows the prosthetic valve to be corrugated to a relatively smaller diameter than if the entire leaflet material were restricted within a corrugated frame. Frame 12 is configured to reduce or. To avoid or minimize possible excessive expansion of the prosthetic valve at a predetermined balloon pressure, especially at the outlet-flow portion of the frame, which supports the blade structure. In one aspect, the frame is configured to have relatively larger angles between endoprostheses, as shown in Figure 5. The larger the angle, the greater the force required to open (expand) the frame. Thus, the angles between the frame endoprostheses can be selected to limit the radial expansion of the frame to a given opening pressure (e.g., balloon inflation pressure).In particular modalities, these angles are at least 110 degrees or greater when the frame is expanded to its functional size, and even more specifically these angles are up to approximately 120 degrees when the frame is expanded to its functional size. Furthermore, the inflow and outflow ends of the frame generally tend to over-expand, such that the middle portion of the frame is affected by a "dog bone" effect of the balloon used to expand the prosthetic valve. To protect against over-expansion of the blade structure 14, the blade structure is, ideally, secured to the frame 12 below the upper row 10 of the endoprosthesis 32, as best shown in Figure 1. In this way, if the outflow end of the frame over-expands, the blade structure is positioned at a lower level where excessive expansion is likely to occur, thereby protecting the blade structure from over-expansion. In a known prosthetic valve construction, portions of the leaflets may protrude longitudinally beyond the outflow end 20 of the frame when the prosthetic valve is compressed if the leaflets are mounted too close to the distal end of the frame. If the placement catheter on which the corrugated prosthetic valve is mounted includes a pusher mechanism or a stop member that pushes against, or makes contact 25 with, the outflow end of the prosthetic valve (e.g., to maintain the corrugated prosthetic position on the placement catheter), the pusher or stop member may damage the exposed leaflet portions that extend beyond the outflow end 5 of the frame.Another benefit of mounting the leaflets in a separate location from the frame's outflow end is that when the prosthetic valve is corrugated onto a placement catheter, the frame's outflow end 12, rather than the leaflets 40, is the most proximal component of the prosthetic valve 10. In this way, if the placement catheter includes a pusher mechanism or a stop member that pushes against or makes contact with the prosthetic valve's outflow end, the pusher mechanism or stop member 15 makes contact with the frame's outflow end and not the leaflets 40, thus preventing damage to the leaflets. Furthermore, as can be seen in Figure 5, the openings 36 in the lowest row of openings in the frame 20 are relatively larger than the openings 38 in the two intermediate rows of openings. This allows the frame, when compressed, to assume an overall tapered shape that tapers from a maximum diameter at the outlet flow end of the prosthetic valve to a minimum diameter 25 at the inlet flow end of the prosthetic valve. When corrugated, the frame 12 has a reduced diameter region that extends along a portion of the frame adjacent to the inlet flow end of the frame, which generally corresponds to the region of the frame covered by the outer skirt 18. In some embodiments, the reduced diameter region is smaller compared to thediameter of the upper portion of the frame (which is not covered by the outer skirt) so that the outer skirt 18 does not increase the overall corrugation profile of the prosthetic valve. When the prosthetic valve is deployed, the frame can expand into a generally cylindrical shape as shown in Figure 4. In one example, the frame of a 26 mm prosthetic valve, when corrugated, has a first diameter of 14 French at the outlet flow end of the prosthetic valve and a second diameter of 12 French at the inlet flow end of the prosthetic valve. The primary functions of the inner skirt 16 2 0 are to help secure the valve structure 1.4 to the frame 1.2 and to assist in forming a good seal between the prosthetic valve and the native annulus by blocking blood flow through the open cells of the frame 12 below the lower edge of the leaflets. The inner skirt 25 16 desirably comprises a tear-resistant, tough material, such as polyethylene terephthalate (PET), although various other synthetic or natural materials (e.g., pericardial tissue) may be used. The skirt thickness is desirably less than approximately 0.15 mm (approximately 6 mils), and ideally less than approximately 0.1 mm (approximately 4 mils), and even more desirably less than approximately 0.05 mm (approximately 2 mils).In certain configurations, the skirt 16 may have a variable thickness; for example, the skirt may be thicker at at least one of its edges than in its center. In one implementation, the skirt 1.6 may comprise a PET skirt that is approximately 0.07 µm thick at its edges and approximately 0.06 mm thick in its center. The thinner skirt may provide better corrugation performance while still providing a good perivalvular seal. The inner skirt 16 can be secured to the inside of the frame 12 by means of sutures 70, as shown in Figure 20. The valve structure 14 can be attached to the skirt by means of one or more reinforcing strips 72 (which collectively can form a cuff), for example, thin PET reinforcing strips, described later, which allows for a secure suture and protects the pericardial tissue from the blade structure by preventing tearing. The valve structure 14 can be interposed between the skirt 16 and the thin PET strips 72, as shown in Figure 19. The sutures 154, which secure the PET strip and the blade structure 14 to the skirt 16, can be any suitable suture, such as Ethibond Ex.celMR PET suture (Johnson & Johnson, Brunswick, New Jersey). Sutures 154 desirably follow the curvature of the lower edge of the 10 blade structure 14, as described in more detail below. Known fabric skirts may comprise a wavy pattern of warp and weft fibers extending perpendicularly to each other and a set of fibers extending longitudinally between the upper and lower edges of the skirt. When the metal frame to which the fabric skirt is secured is compressed radially, the overall axial length of the frame increases. Unfortunately, a fabric skirt with limited elasticity cannot lengthen along with the frame and therefore tends to deform the frame struts and prevent uniform corrugation. With reference to Figure 12, in contrast to known fabric skirts, skirt 16 is desirablely woven from a first set of fibers or yarns or strands 78 and a second set of fibers or yarns or strands 80, both of which are not perpendicular to the upper edge 82 and the lower edge 84 of the skirt. In particular embodiments, the first set of fibers 78 and the second set of fibers 80 extend at angles of approximately 45 degrees (or 15 to 75 degrees or 30 to <50 degrees) relative to the upper and lower edges 82, 84. For example, skirt 16 may be formed by crimping the fibers at angles of 45 degrees relative to the upper and lower edges of the fabric. Alternatively, the...Skirt 16 can be cut diagonally (cut on a bias) from a vertically woven fabric (where the fibers extend perpendicularly to the edges of the material) so that the fibers extend at 45-degree angles relative to the top and bottom cut edges of the skirt. As further shown in Figure 12, the opposite short edges 86, 88 of the skirt are desirablely not perpendicular to the top and bottom edges 82, 84. For example, the bottom edges 86, 88 are desirablely extended at angles of approximately 45 degrees relative to the top and bottom edges and thus align with the first set of fibers 7S. Therefore, the overall shape of the skirt is that of a rhomboid or parallelogram. Figures 13 and 14 show the inner skirt 16 after which the opposing short edge portions 90, 92 have been sewn together to form the annular shape of the skirt. As shown, the edge portion 90 can be placed in an overlapping relationship with the opposite edge portion 92, and the two edge portions can be joined by stitching with a diagonally extending suture line 94 that is parallel to the short edges 86, 88. The upper edge portion of the inner skirt 16 can be shaped with a plurality of projections 96 that define a wavy shape that generally follows the shape or contour of the fourth row of struts 28 immediately adjacent to the lower ends of the axial struts 31. In this way, as best shown in Figure 15, the upper edge of the inner skirt 16 can be securely fastened to the struts 28 with sutures 70. The inner skirt 16 can also be shaped with.Slots to facilitate joining the skirt to the frame. The slots 98 are dimensioned so as to allow the upper edge portion of the inner skirt 16 to be partially wrapped around the struts 28 to reduce stress on the skirt during the joining procedure. For example, in the illustrated embodiment, the inner skirt 16 is placed on the inside of the frame 12, and a portion of the upper edge of the skirt is wrapped around the upper surfaces of the struts 28 and secured in place with sutures 70. Wrapping the upper edge portion of the inner skirt 16 around the struts 28 in this manner provides a stronger and more durable connection of the skirt to the frame. The inner skirt 16 can also be secured to the first, second, and / or third rows of struts 22, 24, and 26, respectively, with sutures 70. Due to the angled orientation of the figures relative to the upper and lower edges, the skirt can experience greater elongation in the axial direction (i.e., in a direction from the upper edge 82 to the lower edge 84). Thus, when the metal frame 12 is corrugated, the inner skirt 16 can elongate in the axial direction along with the frame, thereby providing a more uniform and predictable screening profile. Each cell of the metal frame, as illustrated, includes at least four angled struts that rotate axially over the screening (i.e., the angled struts are more aligned with the length of the frame). The angled struts in each cell function as a mechanism to rotate the skirt fibers in the same direction as the struts, allowing the skirt to elongate along the length of the struts. This enables greater elongation. - 35 of the skirt and avoids undesirable deformation of the struts when the prosthetic valve is corrugated. Furthermore, 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 16 inner skirt made of 20 denier yarn, the yarn density can be approximately 15% to approximately 30% or less than a typical PET skirt. In some examples, the yarn spacing of the 16 inner skirt can be approximately 60 threads per cm (approximately 155 threads per inch) to approximately 70 threads per cm (approximately 180 threads per inch), such as approximately 63 threads per cm (approximately 160 threads per inch), whereas in a typical PET skirt the yarn spacing can be approximately 85 threads per cm (approximately 217 threads per inch) to approximately 97 threads per cm (approximately 247 threads per inch).The oblique edges 86, 88 promote a uniform and even distribution of the fabric material along the inner circumference 20 of the frame during corrugation, thus reducing or minimizing fabric buildup and facilitating uniform corrugation at the smallest possible diameter. Additionally, diagonally cut seams can leave loose overhangs along the cut edges. The oblique edges 86, 88 help minimize this. Compared to a typical skirt construction (fibers running perpendicular to the top and bottom edges of the skirt), the inner skirt construction 16 prevents undesirable deformation of the frame struts and provides more uniform frame corrugation. In alternative embodiments, the skirt may be formed from woven elastic fibers that can stretch in the axial direction during the corrugation of the prosthetic valve. The warp and weft fibers may run perpendicular and parallel to the upper and lower edges of the skirt or, alternatively, may extend at angles between 0 and 90 degrees relative to the upper and lower edges of the skirt, as described above. The inner skirt 16 can be sutured to frame 12 at locations away from suture line 154 so that the skirt can be more flexible in that area. This configuration can avoid stress concentrations at suture line 154, which joins the lower edges of the blades to the inner skirt 16. As indicated above, the sheet structure 14 in the illustrated embodiment includes three flexible sheets 40 (although a greater or lesser number of sheets may be used). Additional information regarding the sheets, as well as additional information regarding skirt material, can be found, for example, in U.S. Patent Application No. 14 / 704,861, filed May 5, 2015. The 40 blades can be secured to each other on their adjacent sides to form commissures 122 of the blade structure (Figure 20). A plurality of flexible connectors 124 (one of which is shown in Figure 16) can be used to interconnect pairs of adjacent blade sides 10 and to mount the blades to the commissure window frame portions 30 (Figure 5). Figure 16 shows the adjacent sides of two 40 blades interconnected by a flexible connector 124. Three 40 blades can be secured to each other, side by side, using three flexible connectors 124, as shown in Figure 17. Additional information regarding the connection of the blades to each other, as well as the connection of the blades to the frame, can be found, for example, in US Patent Application Publication No. 2012 / 0123529. 0 As indicated above, the inner skirt can be used to assist in suturing the blade structure 14 to the frame. The inner skirt 16 can have a temporary wavy marking suture to guide the attachment to the lower edges of each blade 40. The inner skirt 16 itself can be sutured to the frame struts 12 using sutures 70, as indicated above, before securing the blade structure 14 to the skirt 16. The struts that intercept the marking suture are, ideally, not attached to the inner skirt 16. This allows the inner skirt 16 to be more flexible in areas not secured to the frame and minimizes stress concentrations along the suture line that secures the lower edges of the blades to the skirt. As indicated above, when the skirt is secured to the frame, the fibers of the skirt (see figure) are 78, 80.12) They are generally aligned with the angled struts of the frame to promote uniform screening and frame expansion. Figure 18 shows a specific solution for securing the commissure portions 12 2 of the sash structure 14 to the commissure window frame portions 3.0 of the frame. The flexible connector 124 (Figure 17) secures two adjacent sides of two sashes that are folded widthwise, and the top tab portions 112 20 are folded down against the flexible connector. Each top tab portion 112 is folded lengthwise (vertically) to an L-shape, with an inner portion 142 folded against the inner surface of the sash and an outer portion 25 144 folded against the connector 124.The outer portion 144 can be sutured to connector 124 along a suture line 146. Next, the commissure tab assembly is inserted through the commissure window 20 of a corresponding window frame portion 30 and the folds 5 outside the window frame portion 30 can be sutured to portions 144. Figure 18 also shows that the downward-folded upper tongue portions 112 can form a double layer of veneer material at the commissures. The inner portions 142 of the upper tongue portions 112 are laid flat against the two-leaf layers 40 that form the commissures, so that each commissure comprises four layers of veneer material just inside the window frames 30. This four-layer portion of the commissures can be more resistant to bending or hinges compared to the leaf portion 40 just radially inward from a relatively stiff, four-layered portion.This causes the leaflets 40 to primarily articulate at the inner edges 143 of the downward-folded inner portions 142 in response to blood flowing through the prosthetic valve during surgery within the body, as opposed to articulation around or near the axial struts of the window frames 30. Because the leaflets articulate at a location radially inward from the window frames 30, the leaflets can avoid contact with and damage to the frame. However, under high forces, the four-layered portion of the commissures 5 can unfold away around a longitudinal axis adjacent to the window frame 30, with each inner portion 142 folding outward against its respective outer portion 144. For example, this can occur when the prosthetic valve 10 is compressed and mounted on a positioning shaft, allowing for a smaller corrugated diameter.The four-layered portion of the commissures can also unfold apart around the longitudinal axis when the balloon catheter is inflated during prosthetic valve expansion, which can relieve some of the pressure on the commissures caused by the balloon, thus reducing potential damage to the commissures during expansion. After all three commissure flap assemblies have been secured to the respective window frame portions 30, the lower edges of the flaps 40 between the commissure flap assemblies can be secured to the inner skirt 16. For example, as shown in Figure 19, each flap 40 can be sutured to the inner skirt 16 along the suture line 154 25 using, for example, a strand of Ethcbond Excel® PET. The sutures can be inside-out sutures, extending through each flap 40, the inner skirt 16, and each reinforcement strip 72. Each flap 40 and respective reinforcement strip 72 can be sewn separately to the inner skirt 5 16.In this way, the lower edges of the blades are secured to the frame 12 by means of the inner skirt 16. As shown in Figure 19, the blades can be further secured to the skirt with sheet sutures 156 that extend through each reinforcing strip 72, blade 40, and inner skirt 16, while forming loops around the edges of the reinforcing strips 72 and the blades 40. The sheet sutures 156 can be formed from PTFE suture material. Figure 20 shows a side view of the frame 12, the blade suture 14, and the inner skirt 16 after the blade structure 14 and the inner skirt 16 have been secured to the frame 12 and the blade structure 14 to the inner skirt 16. Figure 21 is a flattened view of the outer skirt 18 before its attachment to the frame 12, showing the outer surface of the skirt. Figure 22 is a flattened view of the outer skirt 18 before its attachment to the frame 12, showing the inner surface of the skirt. Figure 23 is a perspective view of the outer skirt before its attachment to the frame 12. The outer skirt 18 25 can be laser-cut or otherwise shaped from a durable and strong material such as PET or various other suitable synthetic or natural materials configured to limit and / or prevent the flow of blood through them.The outer skirt 5 18 may comprise a substantially straight lower edge portion (inflow or upstream) 160 and an upper edge portion (outflow or downstream) 162 defining a plurality of alternating projections 164 and tiled notches 166, 10 generally following the shape of a row of frame struts. The lower and upper edge portions 160, 162 may have other shapes in alternative embodiments. For example, in one implementation, the ISO lower edge portion may be formed with a plurality of projections 15 generally conforming to the shape of a row of frame struts 12, while the upper edge portion 162 may be straight. In particular embodiments, the outer skirt 18 may comprise at least one soft plush surface 20 168 oriented radially outward so as to cushion and seal against native tissues surrounding the prosthetic valve. In certain examples, the outer skirt 18 may be made from any of a variety of woven, knitted, or crocheted fabrics, wherein the 25 surface 168 is the surface of a pile or pile of the fabric. Exemplary fabrics having pile include velour, velvet, corduroy, corded corduroy, terry cloth, fleece, etc. As best shown in Figure 23, the outer skirt may have a base layer 170 5 which may comprise warp and weft yarns woven or knitted in a mesh-like structure. For example, in a configuration.Representatively, the 170 base layer yarns can be plain yarns and can have a denier range from approximately 7 dtex to approximately 10,100 dtex, and can be knitted with a density from approximately 8 columns / cm (20 columns per inch) to approximately 39 columns / cm (100 columns per inch) and from approximately 12 courses / cm (30 courses per inch) to approximately 43 courses / cm (110 courses per inch). The 15 yarns can be made, for example, from biocompatible thermoplastic polymers such as PEI, polytetrafluoroethylene (PTFE), nylon, etc., or any other suitable natural or synthetic fiber. The pile layer 172 may comprise pile yarns 174 woven or knitted into loops. In certain configurations, the pile yarns 174 may be warp or weft yarns of the base layer 170 woven or knitted to form the loops. The pile yarns 174 25 may also be separate yarns—incorporated into the base layer, based on the particular characteristics desired. In a representative configuration, the pile yarns 174 may be plain yarns and may have a denier range of approximately 7 dtex to approximately 100 dtex, 5 and may be knitted with a density from approximately 8 columns / cm (20 columns per inch) to approximately 39 columns / cm (100 columns per inch) and from approximately 12 courses / cm (30 courses per inch) to approximately 43 courses / cm (110 courses per inch). The 10 strands of hair can be made, for example, from biocompatible thermoplastic polymers such as PET, PTFE, nylon, etc.or any other suitable natural or synthetic fiber. In certain embodiments, the loops can be cut so that the pile layer is a pile cut in a manner, for example, of velvet fabric. Figures 1 and 21 illustrate a representative embodiment of the outer skirt configured as velvet fabric. In other embodiments, the loops can remain intact to form a pile with loops in the manner of, for example, terry cloth. Figure 23 illustrates a representative embodiment of the outer skirt in which the pile threads are knitted to form loops. The height of the 174 pile yarns (e.g., the 176 loops) can be the same for all pile yarns across the entire length of the outer skirt, thus providing an outer skirt of constant thickness. In alternative embodiments, the height of the 174 pile yarns can vary along the height and / or circumference of the outer skirt, thereby varying the thickness of the outer skirt along its height and / or circumference, as further described below. The 172 hair layer has a much larger surface area than similarly sized skirts made from flat or woven materials and can therefore increase internal tissue ingrowth compared to known skirts. Promoting tissue ingrowth within the 172 hair layer can decrease perivalvular leakage, increase valve retention at the implant site, and contribute to the long-term stability of the valve. In some configurations, the surface area of ​​the 174 hair threads can be further increased by using textured threads that have an increased surface area due, for example, to a wavy or rippled structure, such as the looped hair configuration in Figure 23. The looped structure and the increased surface area 5 provided by the textured yarn of the loops 176 can allow the loops to act as a scaffold for tissue growth within and around the loops the hairs. The outer skirt designs described herein may also contribute to improved compression susceptibility and shape memory properties of the outer skirt compared to known outer skirts and covers. For example, the hair layer 172 may be flexible so 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 removed. This may help improve the seal between the outer skirt and the tissue of the inactive rings or the surrounding support structure in which the prosthetic valve is deployed. Designs of an implantable support structure adapted to receive and retain a prosthetic valve within the mitral valve are described in related application No. 62 / 449,320 filed on January 23, 2017, and application No. 15 / 876,053 filed on January 19, 2018.The susceptibility to compression provided by the pile layer 172 of the outer skirt 18 is also beneficial in reducing the valve's corrugation profile. Additionally, the outer skirt 18 can prevent portions of the leaf blades from extending. of spaces between the frame struts 12 as the prosthetic valve is corrugated, thus protecting against damage to the blades due to blade perforation between struts. In alternative embodiments, the outer skirt 18 is made of a non-woven fabric such as felt or fibers such as non-woven cotton fibers. The outer skirt 18 can also be made of porous or spongy materials such as, for example, any of a variety of flexible polymer foam materials, or woven fabrics such as woven PET. Various techniques and configurations can be used to secure the outer skirt 18 to the frame 12 and / or the inner skirt 1.6. As best shown in Figure 3, a lower edge portion 180 of the inner skirt 16 can be folded back around the inlet flow end 15 of the frame 12, and the lower edge portion 160 of the outer skirt 18 can be attached to the lower edge portion 180 of the inner skirt 16 and / or the frame 12, for example, with one or more sutures or stitches 182 (as best shown in Figure 2) and / or an adhesive. Instead of or in addition to sutures, the outer skirt 18 can be attached to the inner skirt 16, for example, by ultrasonic welding. In the embodiment illustrated, the lower edge portion 160 of the outer skirt 18 can be looped and the lower ISO edge portion of the inner skirt 16 can be overlapped and secured to the base layer 170 of the outer skirt 18.In other embodiments, the lower edge portion 180 of the inner skirt 16 may extend over one or more rows of loops 176 of the pile layer 172 (see Figure 27), as further described below. In other embodiments, the lower edge portion 180 of the inner skirt 18 may wrap around the inlet flow end of the frame and extend between the outer surface of the skirt and the outer skirt 18 (i.e., the outer skirt 18 is radially outward from the lower edge portion 180 of the inner skirt 18). As shown in Figure 1, each projection 164 of the outer skirt 18 can be attached to the third row III of struts 26 (FIG. 5) of the frame 12. The projections 164 can be wrapped, for example, over respective struts 26 of row III and can be secured with sutures 184. The outer skirt 18 can be further secured to the frame 12 by suturing an intermediate portion of the outer skirt (a portion between the lower and upper edge portions) to the frame struts, such as the struts 24 of the second row II of struts. The height of the outer skirt (as measured from the lower edge to the upper edge) may vary in alternative configurations. For example, in some configurations, the outer skirt may cover the entire outer surface of frame 122, with the lower edge portion 160 secured to the inflow end of frame 12 and an upper edge portion secured to the outflow end of the frame. In another configuration, the outer skirt 18 may extend from the inflow end of the frame to the second row II of the 10 struts 24, or to the fourth row IV of the struts 28, or to a location along the frame between two rows of struts.In other additional embodiments, the outer skirt 18 need not extend the entire length of the inflow end of the frame and, instead, the inflow end of the outer skirt 15 can be secured to another location on the frame, such as to the second row II of struts 24. The outer skirt 18 is desirably sized and shaped relative to the frame such that when the prosthetic valve 10 is in a radially expanded state, the outer skirt 18 fits tightly (in a leak-proof manner) against the outer surface of the frame. When the prosthetic valve 10 is radially compressed to a compressed state for its placement, the portion of the frame on which the outer skirt is mounted may lengthen axially. The outer skirt 18 desirably has sufficient elasticity to stretch in the axial direction under radial compression of the frame so as not to prevent full radial compression of the frame or deformation of the struts during the corrugating process. Traditional skirts that have material slack or folds when the prosthetic valve expands 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 18 is sized to fit tightly around the frame in its fully expanded state, the process of securing the skirt to the frame is greatly simplified. During assembly, the outer skirt can be positioned 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 designed to have slack or folds when they expand radially. As shown in Figure 3, the height of the hair layer 172 can be constant throughout the entire length of the skirt so that the outer skirt 18 has a constant thickness, except along the upper and lower edge portions which can be free of loops to facilitate joining the outer skirt to the frame and / or the inner skirt 16. 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 Figure 24, the loops may comprise lower loops 176a along the lower or upstream portion of the skirt that are of a relatively shorter height (as represented by a thinner cross-sectional area) compared to the upper loops 176b (as represented by a thicker cross-sectional area) along the upper or downstream portion of the skirt. Skirt 18 may 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 Figure 24, the thickness of the outer skirt 176b increases from a minimum thickness along the lower portion to a maximum thickness along the upper portion. Figure 25 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 taller or larger in height compared to the upper loops 176c along the upper portion of the skirt. The skirt 1S may 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 Figure 25, the thickness of the outer skirt 18 decreases from a maximum thickness along the lower portion to a minimum thickness along the upper portion. Figure 26 shows another embodiment 1.a in which the loops comprise lower loops 176g, upper loops 176h, and intermediate loops 176i, which are relatively shorter in height compared to the lower and upper loops. As shown, the lower loops 176g gradually decrease in height from the lower edge of the skirt towards the intermediate loops 1761, and the upper loops 176h gradually decrease in height from the upper edge of the skirt towards the intermediate loops 1761. Thus, in the embodiment of Figure 2.6, 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 a maximum thickness along the upper portion.53 illustrated, the upper portion of the skirt containing the upper loops 176h has the same thickness as the lower portion of the skirt containing the lower loops 176e. In ©other embodiments, the thickness of the skirt portion 5 containing the upper loops 176h may be greater or less than the same thickness of the lower skirt portion containing the lower loops 176g. Furthermore, in any of the forms described above where the loop height varies along with the skirt height, the loop height need not vary gradually from one section of the skirt to another. In this way, an outer skirt can have loops of different heights, where the loop height changes abruptly at locations along the skirt. For example, in the form of Figure 24, the lower portion of the skirt containing the lower loops 176a can extend the entire length of the upper portion of the skirt containing the upper loops 176g without the intermediate loops 176c that form a transition between the upper and lower portions. Instead of, or in addition to, having loops that vary in height along the skirt height, the height of the loops 176 (and therefore the thickness of the outer skirt) can vary along the circumference of the 25 outer skirt, for example, the height of the loops can be increased along the circumferential sections of the skirt where larger separations can be expected between the outer skirt and the native ring, such as the circumferential sections of the skirt that 5 align with the commissures of the native valve. Figures 27 and 28 show an alternative configuration for mounting the outer skirt 18 to the frame 12. In this embodiment, as best shown in Figure 27, the lower edge portion 18G of the inner skirt 16 is wrapped around the inlet flow end of the frame and extends over one or more rows of loops along the lower edge portion 160 of the outer skirt. The lower edge portion 180 of the inner skirt 16 can then be secured to the lower edge portion 160 of the outer skirt, for example, by stitches or seams 186 (Figure 28), an adhesive, and / or welding (e.g., ultrasonic welding). Stitches 186 can also extend around selected struts adjacent to the inlet flow end of the frame.The lower edge portion 180 of the inner skirt is effective in partially compressing the loops of the hair layer 172, which creates a tapered edge at the inlet flow end of the prosthetic valve. The tapered edge reduces the insertion force required 25 to push the prosthetic valve through the introducer sheath when it is being inserted into a patient's body. In a specific implementation, stitches 186 secure the lower edge portion 180 of the inner skirt to the outer skirt 18 at a distance of at least 5 minus 1 r from the lowest edge of the outer skirt. The upper edge portion 162 and the middle portion of the outer skirt can then be secured to the frame as previously described. Figures 29 to 32 show another configuration 10 for mounting the outer skirt 18 to the frame 12. In this embodiment, the outer skirt 18 is initially positioned in a tubular configuration with the base layer 170 facing outwards and the lower edge portion 160 (which may be free of loops 176) positioned 15 between the inner surface of the frame 12 and the lower edge portion 180 of the inner skirt 16, as shown in Figure 30. The lower edge portions of the outer skirt and the inner skirt may be secured to each other, for example, by stitching, an adhesive, and / or welding (for example, ultrasonic welding). In one implementation, the lower edge portions of the outer skirt and the inner skirt are secured to each other with inside-out stitching and locking stitches. The outer skirt 18 is then inverted and pulled upwards around the surface.25 exterior of frame 12 so that the base layer 170 is placed against the outer surface of the frame and the pile layer 172 faces outward, as shown in Figure 2.9. In this assembled configuration, the lower edge portion 1.60 of the outer skirt wraps around the inlet flow end of the frame and is secured to the inner skirt within the frame. The upper edge portion 162 and the middle portion of the outer skirt can then be secured to the frame as previously described. The prosthetic valve 10 can be configured and mounted on a suitable placement device for implantation in a subject. Various catheter-based placement devices are known; an example of a suitable catheter-based placement device includes the one described in U.S. Patent Application Publication No. 2013 / 00030519 and U.S. Patent Application Publication No. 2012 / 0123529. To implant a plastically expandable prosthetic valve 10 within a patient, the prosthetic valve 10, including the outer skirt 18, can be corrugated onto an elongated arrow of a placement device. The prosthetic valve, together with the placement device, can form a placement assembly for implanting the prosthetic valve 10 into a patient's body. The arrow can include an inflatable balloon to expand the prosthetic valve within the body. With the balloon deflated, the prosthetic valve 10 can then be percutaneously placed into a desired implantation location (e.g., a native aortic valve region). Once the prosthetic valve 10 is placed at the implantation site (e.g., the native aortic valve) within the body, the prosthetic valve 10 can be radially expanded to its functional state by infiltrating the balloon or equivalent expansion mechanism. The outer skirt 18 can fill gaps between the frame 12 and the surrounding native ring to help form a good fluid-tight seal between the prosthetic valve 10 and the native ring. The outer skirt 18 therefore cooperates with the inner skirt 16 to prevent perivalvular leakage after implantation of the prosthetic valve 10. Additionally, as described above, the hair layer of the outer skirt further enhances the perivalvular seal by promoting inward tissue growth with the surrounding tissue. Alternatively, a self-expanding prosthetic valve 10 can be corrugated to a radially collapsed configuration and constrained in the collapsed configuration by inserting the prosthetic valve 10, including the outer skirt 18, into a sheath or equivalent delivery catheter mechanism. The prosthetic valve 10 can then be delivered percutaneously to a desired implantation site. Once inside the body, the prosthetic valve 10 can be advanced from the delivery sheath, allowing it to expand to its functional state. Figure 33 illustrates a sealing member 200 for a prosthetic valve, according to another embodiment. The sealing member 200 in the embodiment illustrated is formed from a separating fabric. The sealing member 200 can be placed around the outer surface of the frame of a prosthetic valve (instead of the outer skirt) and is secured to the inner skirt and / or the frame using stitching, an adhesive, and / or welding (for example, ultrasonic welding). As best shown in Figure 34, the separating fabric may comprise a first inner layer 206, a second outer layer 208, and an intermediate separating layer 210 that spans between the first and second layers to create a three-dimensional fabric. The first and second layers 206 to 208 may be woven fabrics or mesh layers. In certain configurations, one or more of the first and second layers 206, 208 may be woven so as to define a plurality of openings 212. In some examples, openings such as 212 may promote tissue growth within the sealing member 200. In other embodiments, the layers 206, 208 need not define openings but may be porous as desired. The separating layer 210 may comprise a plurality of hair strands 214. The hair strands 214 may be, for example, monofilament strands distributed to form a scaffold-like structure between the first and second layers 206, 208. For example, Figures 34 and 35 illustrate an embodiment in which the hair strands 214 extend between the first and second layers 206, 208 in a sinusoidal pattern or in loops. In certain examples, the pile yarns 214 may have a stiffness that is greater than the stiffness of the fabric of the first and second layers 206, 208 so that the pile yarns 214 can extend between the first and second layers 206, 208 without collapsing under the weight of the second layer 208. The pile yarns 214 may also be sufficiently new so that the pile yarns can bend or yield when subjected to a load, allowing the fabric to compress and return to its unbent state when the load is removed.For example, when the prosthetic valve is radially compressed for placement in a patient's body and is placed in a placement sheath of a placement device or advanced through an introducer sheath, the strands of hair 214 may compress or reduce the overall corrugated profile of the prosthetic valve and then return to their undeflected state when deployed from the placement sheath or introducer sheath, as the case may be. The separator fabric can be warp-knitted or weft-knitted, as desired. Some configurations of the separator garment can be produced on a double-bar knitting machine. In a representative example, the first and second layer yarns 206, 208 can have a denier range from approximately 10 dtex to approximately 70 dtex, and the monofilament pile yarns 214 can have a denier range from approximately 51 g / m² (2 mils) to approximately 254 µm² (10 mils). The pile yarns 214 can have a knitting density from approximately 8 columns / cm² (20 columns per inch) to approximately 39 columns / cm² (1000 columns per inch), and from approximately 12 courses / cm² (30 courses per inch) to approximately 43 courses / cm² (110 courses per inch).Additionally, in some configurations (e.g., warp-knitted separator fabrics) materials with different flexibility properties can be incorporated into the separator garment to improve the overall flexibility of the separator garment. Figure 36 shows an outer sealing member 18' mounted on the outside of frame 12 of a prosthetic heart valve 10 according to another modality. Figure 37 shows the base layer 170 of the sealing member 18' in a flattened configuration. Figure 38 shows the hair layer 172 of the sealing member 18' in a flattened configuration. The outer sealing member 18' is similar to the sealing member 18 of Figures 1 and 21 to 23, except that the height (¾.) of the base layer 170 is greater than the height (H.<) of the hair layer 172. As with the embodiments described previously, the sealing member 18' is desirably sized and shaped relative to the frame 12 such that when the prosthetic valve is in its radially expanded state, both layers, 170 and 172, of the sealing member 18 fit tightly (in a hermetic fit) around the outer surface of the frame.In the configuration illustrated, the base layer 170 extends axially from the lead end of frame 12 to the third row III of the struts 26 of frame 12. The upstream and downstream edges of the base layer 170 can be sutured to the struts 22 of the first row I and the struts 26 of the third row III with sutures 182 and 184, respectively, as previously described. The hair layer 172 in the illustrated configuration extends from the lead end of frame 12 to a plane that intersects the frame at the nodes formed at the intersection of the upper ends of the struts 24 of a second row II and the lower ends of the struts 26 of the third row III, where the plane is perpendicular to the center axis of the frame. The 172 hair layer can be formed separately and subsequently bonded to the base layer 170, for example with sutures, an adhesive and / or welding. Alternatively, the hair layer 172 can be formed from yarns or fibers woven into the base layer 170. The hair layer 172 can have any of the configurations shown in Figures 24 to 26. In particular modalities, the height Hi of the base layer 170 can be from approximately 9 mm to approximately 25 mm or from approximately 13 mm to approximately 20 mm, with approximately 19 mm constituting a specific example. The height Hs of the 1-layer of pile 172 can be at least 2 mm less than Hi, at least 3 mm less than Hx, at least 4 mm less than Hi, at least 5 mm less than Hi, at least 0.6 mm less than Hi, at least 7 mm less than Hi, at least 8 mm less than Hi, at least 9 mm less than Hi, or at least 10 mm less than Hi. The height of the frame 12 in the radially expanded state can be from approximately 2 mm to approximately 27 mm or from approximately 15 mm to approximately 23 mm, with approximately 20 mm constituting a specific example. The relatively shorter 172 hair stage reduces the corrugated profile along the midsection of the prosthetic valve 10 while still providing increased valve sealing along most of the prosthetic valve placement zone. The 170 base layer 10 also provides a sealing function downstream of the downstream edge of the 172 hair layer. Figures 3.9 to 40 show an outer sealing member 300 for a prosthetic heart valve (e.g., a prosthetic heart valve 10) according to another modality. Figures 39A and 40A are enlarged views of portions of the sealing member shown in Figures 39 and 40, respectively. The sealing member 300 can be mounted on the outside of the frame 12 of a prosthetic valve 10 in view of the sealing member 18 using (e.g., sutures, ultrasonic welding, or any other suitable joining method). As with the modality described previously, the sealing member 300 is desirably sized and shaped relative to the frame 12 such that when the prosthetic valve is in its radially expanded state, the sealing member 300 fits tightly (in a hermetic fit) against the outer surface of the frame. The sealing member 300, like the sealing members 18, 18, can be a double-layered fabric comprising a base layer 302 and a pile layer 304. Figure 39 shows the outer surface of the sealing member 300 defined by the pile layer 304. Figure 40 shows the inner surface of the sealing member 300 defined by the base layer 302. The base layer 302 in the illustrated configuration comprises a crimped mesh having circumferentially extending rows or strips 306 of higher-density mesh portions interspersed with rows or strips 308 of lower-density mesh portions. In particular modalities, the thread count of threads extending in the circumferential direction (side to side or horizontally in Figures 40 and 40A) is greater in the rows of higher density 306 compared to the rows of lower density 308. In other modalities, the thread count of threads extending in the circumferential direction and the thread count of threads extending in the axial direction (vertically in Figures 40 and 40A) is greater in the rows of higher density 306 than in the rows of lower density 308. The pile layer 304 can be formed from yarns woven into the base layer 302. For example, the pile layer 304 can comprise a wavy velvet formed from yarns incorporated into the base layer 302. The pile layer 304 can comprise rows or strips that extend circumferentially 310 and are formed at axially spaced locations along the height of the sealing member 300, such that there are axially extending gaps between adjacent rows 310. In this way, the density of the pile layer varies along the height of the sealing member. In alternative embodiments, the pile layer 304 can be formed without gaps between adjacent rows of piles, but the pile layer can comprise circumferentially extending rows or strips of piles of higher density interspersed with rows or strips 312 of piles of lower density. In alternative modalities, the 302 base layer may comprise a uniform mesh crim (the density of the crim pattern is uniform) and the 30420 pile layer has a variable density. Varying the density of the 304 hair layer and / or the 302 base layer along the height of the sealing member 300 is advantageous because it facilitates axial elongation of the sealing member 300 caused by axial elongation of the frame 12 when the prosthetic heart valve is corrugated to a radially compressed state for placement. The variable density also reduces the volume of the sealing member in the radially collapsed state and thus reduces the overall corrugation profile of the prosthetic heart valve. In alternative embodiments, the density of the sealing member 300 may vary along with the circumference of the sealing member to reduce the volume of the sealing member in the radially collapsed state. For example, the hair layer 304 may comprise a plurality of circumferentially spaced, axially extending rows of hair strands, or alternatively, alternating axially extending rows of higher-density hairs interspersed with axially extending rows of lower-density hairs. Similarly, the base layer 302 may comprise a plurality of axially extending rows of higher-density mesh interspersed with rows of lower-density mesh. In other embodiments, the sealing member 300 20 may include a base layer 302 and / or a hair layer 304 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 25 may 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. Figure 41, for example, shows a sealing member 400 that is made of a fabric having a plurality of axially extending rows 402 of higher density joined by alternating stitches with axially extending rows 404 of lower stitch density. The sealing member 400 may be formed, for example, by knitting, crocheting, or crimping a single-layer fabric having rows 402, 406 formed by increasing the stitch density along row 402 and decreasing the stitch density along rows 404 while forming the fabric.The sealing member 400 can be mounted on the outside of the frame 12 of a prosthetic valve 10 in view of the sealing member 18 using, for example, sutures, ultrasonic welding, or any other suitable joining method. As with the embodiments described previously, the sealing member 400 is desirably sized and shaped relative to the frame 12 such that when the prosthetic valve is in its radially expanded state, the sealing member 400 fits tightly (in a hermetic fit) against the outer surface of the frame. The sealing member 400 can be resiliently stretched between a first substantially relaxed, axially shortened configuration (Figure 41) corresponding to a radially expanded state of the prosthetic valve and a second axially elongated or tensioned configuration (Figure 42) corresponding to a radially compressed state of the prosthetic valve. As shown in Figure 41, with the prosthetic valve radially expanded and the sealing member 400 in the first configuration, the larger density rows 402 extend in a wavy pattern from the bottom (upstream edge) to the top (downstream edge) of the sealing member 400.In the embodiment illustrated, for example, each of the higher density rows 402 comprises a plurality of right-angle sections 406a, 406b distributed end-to-end in a zigzag or herringbone pattern extending from the bottom (upstream edge) to the top (downstream edge) of the sealing member 400. In alternative embodiments, the rows 402 may be sinusoidal rows having curved longitudinal edges. When the prosthetic valve is corrugated to its radially compressed state, frame 12 elongates, causing the sealing member to stretch axially, as shown in Figure 42, to its second configuration. The lower density rows 404 facilitate the elongation of the sealing member and allow the higher density rows 402 to straighten. Figure 42 shows the higher density rows 402 as straight sections extending from the inlet flow edge to the outlet flow edge of the sealing member. However, it should be understood that the higher density rows 402 do not need to form perfectly straight rows when the prosthetic valve is in a radially compressed state. Instead, the straightening of the higher density rows 402 occurs when the angle 408 between adjacent angled segments 10 4 06 a, 406b of each row increases with axial elongation of the sealing member. The variable stitch density of the sealing member 400 reduces the overall volume of the sealing member to minimize the corrugation profile of the prosthetic valve 15. The zigzag or wavy pattern of the higher density rows 402 in the radially expanded state of the prosthetic valve facilitates stretching of the sealing member in the axial direction under radial compression of the prosthetic valve and allows the sealing member 20 to return to its pre-stretched state in which the sealing member fits tightly around the frame under radial expansion of the prosthetic valve.Additionally, the zigzag or wavy pattern of the higher density rows 402 in the radially expanded state of the prosthetic valve 25 eliminates any straight flow paths for blood between adjacent rows 402 that extend along the outer surface of the sealing member from its outflow edge to its inflow edge to facilitate sealing and inward tissue growth 5 with surrounding tissue. In alternative embodiments, a sealing member 400 may have a plurality of circumferentially extending rows of higher density (like rows 402 but extending in the circumferential direction) interposed with a plurality of circumferentially extending rows of lower density (like rows 404 but extending in the circumferential direction). In some embodiments, a sealing member 400 may have axially extending and circumferentially extending rows of higher density interposed with axially extending and circumferentially extending rows of lower density. Figures 4.3A, 4.3B, 4.4A, and 4.48 illustrate an outer sealing member 500 for a prosthetic heart valve 2.0 (e.g., a prosthetic heart valve 10), according to another modality. The sealing member 500 may have a plush outer surface 504. The sealing member 500 may be secured to the prosthetic valve frame 12 using, for example, sutures, ultrasonic welding 25, or any other suitable joining method as previously described herein. For illustrative purposes, enlarged or magnified portions of the sealing member 500 are shown in the figures. It should be understood that the overall size and shape of the sealing member 500 may be modified as required to cover the entire outer surface of the frame 12 or a portion of the outer surface of the frame, as previously described herein. The sealing member 500 may comprise a woven or knitted fabric. The fabric may be resiliently stretchable between a first natural or relaxed configuration (Figure 43A) and a second axially elongated or tensioned configuration (Figure 43E). When placed on the frame 12, the relaxed configuration may correspond to the radially expanded functional configuration of the prosthetic valve, and the elongated configuration may correspond to the radially collapsed placement configuration of the prosthetic valve. Thus, with reference to Figure 43A, the sealing member 500 may have a first length Li in the axial direction when the prosthetic valve is in the radially expanded configuration, and a second length La (Figure 43B) in the axial direction that is greater than Li when the valve is corrugated to the placement configuration, as described in more detail below. The fabric may comprise a plurality of circumferentially extending warp yarns 512 and a plurality of axially extending weft yarns 514. In some embodiments, the warp yarns 512 may have a thickness ti (Figure 44A) of approximately 0.01 mm to approximately 0.5 mm, approximately 0.02 mm to approximately 0.3 mm, or approximately 0.03 mm to approximately 0.1 mm. In some embodiments, the warp yarns 512 may have a thickness ti of approximately 0.03 mm, approximately 0.04 mm, approximately 0.05 mm, approximately 0.06 mm, approximately 0.07 mm, approximately 0.08 mm, approximately 0.09 mm, or approximately 0.1 mm. In a representative embodiment, the warp yarns 512 may have a thickness of approximately 0.06 mm. Weft yarns 514 may be textured yarns comprising a plurality of textured filaments. 516. For example, the filaments 516 of weft yarns 514 may have volume, wherein, for example, the filaments 516 are twisted, heat-set, and straightened so that the filaments retain their deformed, twisted shape in the relaxed, unstretched configuration. Filaments 516 may also be textured by corrugating, winding, etc. When weft yarns 514 25 are in a relaxed, unstretched state, the filaments 516 weft yarns can be loosely packed and can provide compressible bulk or volume to the fabric, as well as a plush surface. In some embodiments, 514 weft yarns can have a denier from approximately 1D to approximately 500D, approximately 10D to approximately 400D, approximately 20D to approximately 350D, approximately 20D to approximately 300D, or approximately 40D to approximately 200D. In certain embodiments, 514 weft yarns can have a denier of approximately 150D. In some embodiments, the filament count of 514 weft yarns can range from 2 filaments per yarn to 200 filaments per yarn, 10 filaments per yarn, 20 filaments per yarn to 80 filaments per yarn, or approximately 30 filaments per yarn to 60 filaments per yarn.Additionally, the axially extending textured yarns 514 are referred to as the weft yarns in the configuration illustrated; the tc-ibién fabric can also be manufactured so that the axially extending textured yarns are warp yarns and the circumferentially extending yarns are weft yarns. Figures 44A and 44B illustrate a cross-sectional view of the sealing member in which the 512 weft yarns are laid out in the plane of the page. With reference to Figure 44A, the sealing member fabric The 500 sealing member can have a thickness from approximately 0.1 mm to approximately 10 mm, approximately 1 mm to approximately 8 mm, approximately 1 mm to approximately mm, approximately 1 mm to approximately 3 mm, approximately mm, approximately mm, approximately 1 mm, approximately mm, approximately 2.5 mm, or approximately 3 mm when in a relaxed state and secured to a frame. In some embodiments, the 500 sealing member can have a thickness of approximately 0.1 mm, approximately 0.2 mm, approximately 0.3 mm, approximately 0.4 mm, or approximately 0.5 mm measured in a relaxed state with a weighted drop gauge having a pressing leg. In a representative example, the sealing member can have a thickness of approximately 1.5 mm when secured to a prosthetic valve frame in the relaxed state.Loosely packed and textured filaments 516 of weft yarns 514 in the relaxed state can also promote tissue growth within sealing member 500. When the fabric is in a relaxed state, the textured filaments 516 of the weft yarns 514 can be widely dispersed so that the individual weft yarns are not easily discernible, as shown in Figure 43A. When tension is applied in the direction. Axially, the filaments 516 of the weft yarns 514 can be pulled together as the weft yarns and the twists, turns, etc. of the filaments are pulled straightening them so 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 embodiment illustrated), for example when a prosthetic valve is corrugated over a shaft of a fitting appliance, the textured fibers 516 can be pulled together so that the individual weft yarns 514 become discernible, as best shown in Figure 43B. Thus, for example, when fully stretched, the sealing member may have a second thickness t3, as shown in Figure 44B, which is less than the thickness ti. In certain embodiments, the thickness of the tensioned weft yarns 514 may be equal to or nearly equal to the thickness ti of the weft yarns 512. Thus, in certain examples, when the fabric is stretched, it may have a thickness t3 that is equal to or equal to three times the thickness ti of the warp yarns 512, depending, for example, on the amount of flattening of the weft yarns 514. Consequently, in the previous example where the warp yarns 512 have a thickness of approximately 0.06 mm, the thickness of the sealing member 25 may vary between approximately 0.2 mm and approximately 1.5 mm as the fabric stretches and relaxes. In other words, fabric thicknesses can vary by 750% or more as the fabric stretches and relaxes. Additionally, as shown in Figure 44A, the warp threads 512 can be separated from each other in the fabric by a distance yi when the outer covering is in a relaxed state. As shown in Figures 43B and 44B, when tension is applied to the fabric in the direction perpendicular to the warp threads 512 and parallel to the weft threads 514, the distance between the warp threads 512 can be increased as the weft threads 514 are lengthened. In the example illustrated in Figure 44B, where the fabric has been stretched so that the weft threads 514 have been lengthened and narrowed to approximately the diameter of the warp threads 512, the distance between the warp threads 512 can be increased to a new distance since it is greater than the distance yi. In certain embodiments, the distance can be, for example, approximately 1 mm to approximately 10 mm, approximately 2 mm to approximately 8 mm, or approximately 0.3 mm to approximately 5 mm. In a representative example, the distance yi can be approximately 3 mm. In some embodiments, when the fabric is stretched 0.25 as in Figures 43B and 44B, the distance yi can be approximately 6 mm to approximately 10 mm. Thus, in certain embodiments, the length of the sealing member 50.0 in the axial direction can vary by 100% or more between the relaxed length Li and the fully stretched length (e.g., Li). The fabric's ability to elongate in this way facilitates the corrugation of the prosthetic valve.Thus, the sealing member 500 can be smooth and bulky when the prosthetic valve expands to its functional size and relatively thin when the prosthetic valve is corrugated, to minimize the overall corrugation profile of the prosthetic valve. GENERAL CONSIDERATIONS It should be understood that the described modalities can be adapted to place and implant prosthetic devices in any of the heart's native rings (e.g., the pulmonary, mitral, and tricuspid rings) and can be used with any of various solutions (e.g., retrograde, antegrade, transseptal, transventricular, transatrial, etc.). The described modalities can also be used to implant prostheses in other body lumens. Furthermore, in addition to prosthetic valves, the placement and assembly modalities described herein can be adapted for the placement and implantation of various other prosthetic devices, such as endoprostheses and / or other prosthetic repair devices. For the purposes of this description, certain aspects, advantages, and novel features of the modalities described herein are mentioned. The methods, apparatus, and systems described should not be considered limiting in any way. Instead, this description relates to all the novel and non-obvious features and aspects of the various modalities described, alone and in various combinations and secondary combinations with each other. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the modalities described require that any of one or more specific advantages be present or that any problems be solved. Although the operations of some of the mentioned modalities are described in a particular sequential order for convenient presentation, it should be understood that this mode of description includes rearrangement, unless a particular ordering is required by a specific language, which is established later. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Furthermore, for the sake of simplicity, the accompanying figures may not show the various ways in which the described methods can be used in conjunction with other methods. Additionally, the description sometimes uses terms such as “provide” or “obtain” to describe the methods shown. These terms are high-level abstractions of the actual operations performed.The actual operations that correspond to these terms may vary based on the particular implementation and are easily discernible by a person usually expert in the field. As used in this application and in the claims, the singular forms a, one, and the include the plural forms unless the context clearly determines otherwise. Additionally, the term "includes" means comprising. Furthermore, the terms coupled and associated generally mean coupled or linked electrically, electromagnetically, and / or physically (e.g., mechanically or chemically) and do not exclude the presence of intermediary elements between coupled or associated articles in the absence of 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 farther from the implantation site. As used herein, the term 'distal' refers to a position, direction, or portion of a device that is farther from the user and closer to the implantation site. Thus, for example, proximal movement of a device is movement of the device toward the user, while distal movement of the device is movement of the device away from the user. The terms 'longitudinal' and 'axial' refer to an axis extending in the proximal and distal directions, respectively, unless expressly defined otherwise. As used herein, the terms “integrally formed” and “unit construction” refer to a construction that does not include any type of welding, fastener, or other means of securing separately formed pieces or materials together. As used herein, operations that are carried out simultaneously or concurrently* generally occur at the same time as each other, although delays in the performance of one operation in relation to the other may occur, due, for example, to separation, clearance, or play between components at a joint. 2.0 mechanical elements such as threading, gears, etc. are expressly included within the scope of the above terms, in the absence of specific contrary language. In view of the many possible embodiments to which the principles of the described invention may be applied, it should be recognized that the embodiments illustrated are merely preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. Therefore, we claim as our invention everything that falls within the scope and spirit of these claims. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A prosthetic heart valve, characterized in that it comprises: an annular frame comprising an inflow end and an outflow end, both of which are radially compressible and expandable between a radially compressed configuration and a radially expanded configuration; a box structure positioned within and secured to the frame; an outer sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within the annulus of a patient's native heart valve, the sealing member comprising a mesh layer and a layer of 2. 20 hairs comprising a plurality of hair strands extending outward from the mesh layer.

2. The prosthetic heart valve according to claim 1, characterized in that the mesh layer comprises a knitted or woven fabric. 25 3. The prosthetic heart valve according to any of the preceding claims, characterized in that the hair strands are distributed to form a set of looped hairs.

4. The prosthetic heart valve in accordance with any of the preceding claims, characterized in that the hair strands are cut to form a set of cut hairs.

5. The prosthetic heart valve according to any of the preceding claims, 10 characterized in that the height of the hair strands varies along the height and / or circumference of the outer skirt.

6. The prosthetic heart valve according to claim 5, characterized in that the 15-hair threads comprise a first group of threads along an upstream portion of the outer skirt and a second group of threads along a downstream portion of the outer skirt, wherein the threads of the first group have a height that is less than the height of the threads of the second group.

7. The prosthetic heart valve according to claim 5, characterized in that the hair strands comprise a first group of strands along an upstream portion of the outer skirt and a second group of strands along a downstream portion of the outer skirt, wherein the strands of the first group have a height that is greater than the height of the strands of the second group.

8. The prosthetic heart valve according to claim 5, characterized in that the hair strands comprise a first group of strands along an upstream portion of the outer skirt, a second group of strands along a downstream portion of the outer skirt, and a third group of strands between the first and second groups of strands, wherein the strands of the first and second groups have a height that is greater than the height of the strands of the third group.

9. The prosthetic heart valve according to any of the preceding claims, characterized in that it further comprises an inner skirt mounted on an inner surface of the frame, the inner skirt having an inlet flow end portion that is secured to an inlet flow end portion of the outer sealing member.

10. The prosthetic heart valve according to claim 9, characterized in that the inlet flow end portion of the inner skirt is wrapped around an inlet flow end of the frame and overlaps the inlet flow end portion of the outer sealing member on the outside of the frame.

11. The prosthetic heart valve according to any of the preceding claims, characterized in that the mesh layer comprises a first mesh layer and the outer sealing member further comprises a second mesh layer positioned radially outside the hair layer.

12. The prosthetic heart valve according to any of the preceding claims, characterized in that the outer sealing member is configured to stretch axially when the frame is radially compressed to the radially compressed state. 1.

3. The prosthetic heart valve according to any of the preceding claims, characterized in that the mesh layer comprises warp yarns and weft yarns woven with the warp yarns, and 1.a. the pile layer comprises the warp or weft yarns of the mesh layer woven or knitted to form the pile yarns.

13.

14. The prosthetic heart valve according to any of claims 1 to 12, characterized in that the mesh layer comprises a woven fabric layer and the hair layer comprises a separate hair layer that is sewn to the woven fabric layer.

14.

15. The prosthetic heart valve according to any of the preceding claims, characterized in that the mesh layer has a first height extending axially along the frame and the hair layer comprises a second height extending axially along the frame wherein the first height is greater than the second height.

15.

16. The prosthetic heart valve according to claim 15, characterized in that the mesh layer extends closer to the outflow end of the frame compared to the hair layer.

16.

17. A prosthetic heart valve, characterized in that it 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; a blade structure positioned within and secured to the frame; an outer sealing member mounted outside the frame and adapted to seal against the surrounding tissue when the prosthetic heart valve is implanted within a ring of a patient's native heart valve, the sealing member comprising a fabric having a variable thickness.

17.

18. The prosthetic heart valve according to claim 1.7, characterized in that the thickness of the fabric layer varies along the height and / or circumference of the outer sealing member. 5 18.

19. The prosthetic heart valve according to claims 17 or 18, characterized in that the fabric comprises a plush fabric.

19.

20. The prosthetic heart valve according to any of claims 17 to 19, 10 characterized in that the fabric comprises a plurality of hair threads and the height of the hair threads varies along the height and / or circumference of the outer skirt.

20.

21. The prosthetic heart valve according to claim 20, characterized in that the hair strands comprise a first group of strands along an upstream portion of the outer skirt and a second group of strands along a downstream portion of the outer skirt, wherein the strands of the first group have a height that is less than the height of the strands of the second group.

21.

22. The prosthetic heart valve according to claim 2.0, characterized in that the hair strands comprise a first group of strands along an upstream portion of the outer skirt and a second group of strands along a downstream portion of the outer skirt, wherein the strands of the first group have a height that is greater than the height of the strands of the second group. 5 23. The prosthetic heart valve according to claim 20, characterized in that the hair strands comprise a first group of strands along an upstream portion of the outer skirt, a second group of strands along the downstream portion of the outer skirt, and a third group of strands between the first and second groups of strands, wherein the strands of the first and second groups have a height that is greater than the height of the strands of the third group.

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