Skirt assembly of an implantable prosthetic valve

Abstract

The present application relates to a skirt assembly for an implantable prosthetic valve. Embodiments of the implantable prosthetic valve are disclosed. The valve may have an annular frame having a plurality of frame members and a skirt assembly. The skirt assembly may include a laminate having a fabric layer sandwiched between a first cover member and a second cover member. At least one surface of the fabric layer may be exposed at one or more windows in the second cover member. The skirt assembly may be coupled to the annular frame by sutures extending through the fabric layer at the one or more windows and around at least one of the plurality of frame members. A method for manufacturing such an implantable prosthetic valve is also disclosed.

Description

[0001] This application is a divisional application of Chinese patent application 2018800648241 (PCT / US2018 / 046487) entitled “Skirt assembly for implantable prosthetic valve” filed on August 13, 2018. Technical Field

[0002] The present disclosure relates to embodiments of a prosthetic valve for implantation into a body conduit, such as a native heart valve annulus. Background Art

[0003] A person's heart may develop various valve diseases. These valve diseases can lead to serious heart malfunction and ultimately require replacement of the native valve with an artificial valve. There are many known artificial valves and many known methods for implanting these artificial valves in the human body.

[0004] Various surgical techniques can be used to replace or repair diseased or damaged valves. Due to stenosis and other heart valve diseases, thousands of patients undergo surgery each year in which the defective native heart valve is replaced with a prosthetic valve. Another less severe way to treat a defective valve is through repair or reconstruction, which is usually performed on valves with minimal calcification. The problem with surgical treatment is that it carries a significant risk to patients with these chronic conditions due to the high morbidity and mortality associated with surgical repair.

[0005] When replacing a native valve, surgical implantation of a prosthetic valve typically requires open-chest surgery during which the heart is stopped and the patient is placed on cardiopulmonary bypass (a so-called "heart-lung machine"). In one common surgical procedure, the diseased native valve leaflets are excised and the prosthetic valve is sutured to the surrounding tissue at the valve annulus. Due to the trauma associated with the procedure and the resulting duration of extracorporeal blood circulation, some patients do not survive the surgical procedure or die shortly thereafter. It is well known that the risk to the patient increases with the amount of time required for extracorporeal circulation. Due to these risks, a large number of patients with defective native valves are considered inoperable because their condition is too frail to withstand the procedure. According to some estimates, more than 50% of subjects over the age of 80 with valvular stenosis are unable to undergo valve replacement surgery.

[0006] Due to the drawbacks associated with conventional open-heart surgery, percutaneous and minimally invasive surgical approaches have received significant attention. In one technique, prosthetic valves are configured to be implanted in a less invasive procedure via catheterization. For example, U.S. Patents Nos. 5,411,522 and 6,730,118 describe collapsible transcatheter heart valves that can be percutaneously introduced over a catheter in a compressed state and expanded at a desired position by balloon inflation or by using a self-expanding frame or stent.

[0007] Known prosthetic valves include a frame having a valve structure (e.g., leaflets) mounted therein, an inner skirt secured to the interior of the frame, and optionally an outer skirt secured to the exterior of the frame. The inner skirt can serve a variety of functions. For example, the inner skirt can act as a sealing member to prevent (or reduce) paravalvular leakage, anchor the leaflets to the frame, and protect the leaflets from damage caused by contact with the frame during curling and during the operating cycle of the valve. The outer skirt can cooperate with the inner skirt to further reduce or avoid paravalvular leakage after the valve is implanted. The inner skirt ideally comprises a tough, tear-resistant material, such as polyethylene terephthalate (PET), although various other synthetic or natural materials can be used.

[0008] The inner and outer skirts are typically secured to the frame by suturing or sewing the fabric of the respective skirts to the frame. Suturing the inner skirt to the frame can expose the leaflets to the sutures. During the valve's operating cycle, repeated contact between the leaflets and the exposed sutures, as well as contact between the leaflets and the fabric material of the skirt, can lead to wear of the leaflets. Therefore, improvements in skirts for prosthetic valves are desirable. Summary of the Invention

[0009] The present disclosure relates to methods and apparatus relating to prosthetic valves, such as prosthetic heart valves.

[0010] Certain embodiments of the present disclosure relate to a method for manufacturing an implantable prosthetic valve. An exemplary embodiment of the method includes forming a laminate comprising a fabric layer disposed between a first covering member and a second covering member. The second covering member may include one or more windows through which the fabric layer is exposed. The method further includes placing the laminate against an annular frame, and suturing the laminate to the annular frame by passing sutures through the fabric layer at the one or more windows of the second covering member and around a portion of the frame.

[0011] In certain embodiments, the laminate may include an annular skirt sized and shaped to cover the opening in the frame to prevent blood from flowing through the frame opening.

[0012] In some embodiments, the skirt may be positioned interior to the annular frame.

[0013] In the aforementioned embodiments, the first covering member and the second covering member may be fused to each other through the openings in the fabric layer.

[0014] In the aforementioned embodiment, forming the laminate may include forming a first covering member by electrospinning, placing a fabric layer on the electrospun first covering member, and forming a second covering member on the fabric layer by electrospinning.

[0015] In certain embodiments, forming the laminate may further include masking one or more areas on the fabric layer prior to forming the second covering member so that when the second covering member is formed on the fabric layer, one or more windows are formed in the second covering member.

[0016] In some embodiments, forming the laminate may include masking one or more areas on at least one side of the fabric layer with a masking material, immersing the fabric layer in a liquefied polymer material, allowing the liquefied polymer material to solidify, and removing the masking material to form one or more windows in the laminate.

[0017] In certain embodiments, the one or more windows in the second covering member may extend continuously in a circumferential direction around the laminate.

[0018] In certain embodiments, the first cover member and the second cover member comprise an elastic material.

[0019] In certain embodiments, the elastic material may include expanded polytetrafluoroethylene (ePTFE) or ultra-high molecular weight polyethylene (UHMWPE) or polyurethane.

[0020] Certain embodiments of the present disclosure also relate to an implantable prosthetic valve. A representative implantable prosthetic valve may include a skirt assembly and an annular frame having a plurality of frame members. The skirt assembly may include a laminate having a fabric layer sandwiched between a first cover member and a second cover member. The fabric layer may be exposed at one or more windows in the second cover member. The skirt assembly may be coupled to the annular frame by sutures extending through the fabric layer at the one or more windows and around at least one of the plurality of frame members.

[0021] In certain embodiments, the skirt assembly may be positioned interior to the annular frame.

[0022] In some embodiments, the implantable prosthetic valve can further include a plurality of leaflets sewn to the skirt assembly. The leaflets can be configured to allow blood to flow through the prosthetic valve in a first direction and to prevent blood from flowing through the prosthetic valve in a second direction opposite to the first direction.

[0023] In the aforementioned embodiments of the implantable prosthetic valve, the first covering member and the second covering member can be fused to each other through the openings in the fabric layers.

[0024] In the aforementioned embodiments of the implantable prosthetic valve, the first covering member or the second covering member can include a film of nonwoven fibers.

[0025] In the aforementioned embodiments of the implantable prosthetic valve, the first covering member or the second covering member can be non-absorbable and have a porous microstructure that promotes ingrowth of surrounding tissue to help secure the prosthetic valve in the body lumen.

[0026] In the aforementioned embodiments of the implantable prosthetic valve, the annular frame can have an inlet end and an outlet end and be configured to be radially collapsible and expandable. The plurality of frame members can define a plurality of gaps between the frame members, and the skirt assembly can be configured to prevent blood from flowing through those gaps in the frame covered by the skirt assembly.

[0027] In certain embodiments, the skirt assembly may be sewn to the frame only at the one or more windows in the second covering member.

[0028] In certain embodiments, the first cover member and the second cover member may comprise an elastic material.

[0029] In certain embodiments, the elastic material may include ePTFE or UHMWPE or polyurethane.

[0030] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A side view of an exemplary embodiment of an implantable prosthetic valve is shown.

[0032] Figure 2 Show Figure 1 A top perspective view of a prosthetic valve.

[0033] Figure 3 Show Figure 1 An exemplary frame for a prosthetic valve.

[0034] Figure 4 Show Figure 3 Flattened view of the frame shown.

[0035] Figure 5 Shown along Figure 1 The line 5-5 is intercepted Figure 1 Cross-sectional view of a prosthetic valve.

[0036] Figure 6 Shown according to the manufacturing Figure 1 An exemplary process for forming an inner skirt of a prosthetic valve forms a first cover member on a mandrel.

[0037] Figure 7 An exemplary process for manufacturing an inner skirt is shown. Figure 6 A fabric layer is shown positioned over the first covering member.

[0038] Figure 8 An exemplary process for manufacturing an inner skirt is shown. Figure 7 A plurality of masks are placed on the fabric layer shown.

[0039] Figure 9 An exemplary process for manufacturing an inner skirt is shown. Figure 8 The mask is shown with a second covering member formed on the fabric layer.

[0040] Figure 10 The exemplary process of manufacturing the inner skirt is shown in FIG. Figure 9 The second cover member is shown after which the mask is removed.

[0041] Figure 11 Shown is a cross-sectional view of a portion of an inner skirt having a window on one side of the inner skirt exposing the underlying woven fabric.

[0042] Figure 12 Shown in Figure 11 The suture is passed through the woven fabric at the window shown.

[0043] Figure 13 Show that Figure 11 The inner skirt is shown sutured to adjacent struts of a prosthetic valve frame. DETAILED DESCRIPTION

[0044] Figures 1 to 2 Two different views of a prosthetic valve 10 are shown according to one embodiment. The valve shown is adapted for implantation in the native aortic valve annulus, however, in other embodiments, it may be adapted for implantation in other native valve annuli of the heart. Valve 10 may have several main components: a stent or frame 12, a valve structure 14, and a skirt assembly 15. Skirt assembly 15 may include an inner skirt 16 and, optionally, an outer skirt 18.

[0045] The valve structure 14 (or leaflet structure) can include three leaflets 40 (although a greater or lesser number of leaflets can be used) that collectively form a leaflet structure that can be arranged to collapse in a tricuspid valve arrangement. The valve structure 14 is configured to allow blood to flow through the prosthetic valve 10 in a direction from an inlet end 48 of the prosthetic valve to an outlet end 50 of the prosthetic valve, and to prevent blood from flowing through the prosthetic valve in a direction from the outlet end 50 to the inlet end 48.

[0046] Each leaflet 40 ideally has a curved, generally U-shaped inlet or pointed edge 52. In this way, the inlet edge of the valve structure 14 has an undulating, curved, fan-shaped shape. By forming the leaflets in this fan-shaped geometry, the stress on the leaflets can be reduced, which in turn improves the durability of the valve. In addition, by the fan-shaped shape, wrinkles and ripples at the belly of each leaflet (the central area of each leaflet) that may cause early calcification in those areas can be eliminated or at least minimized. The fan-shaped geometry also reduces the amount of tissue material used to form the leaflet structure, thereby allowing a smaller, more uniform curl profile at the inflow end of the valve. The leaflets 40 can be formed of pericardial tissue (e.g., bovine pericardial tissue), biocompatible synthetic materials, or various other suitable natural or synthetic materials known in the art and described in U.S. Patent No. 6,730,118.

[0047] Figure 3 The frame 12 is shown bare. In the depicted embodiment, the frame 12 has an annular shape defining an inlet end 54 and an outlet end 56 and includes a plurality of struts (or frame members). The frame 12 can be formed with a plurality of circumferentially spaced slits or commissure windows 20 (three in the illustrated embodiment) adapted to mount the commissures 58 of the valve structure 14 to the frame, as more fully described in U.S. Patent Publication No. US2012 / 0123529.

[0048] The frame 12 can be made of any of various suitable plastic expansion materials (e.g., stainless steel, etc.) or self-expanding materials (e.g., Nitinol) known in the art. When constructed of a plastic expansion material, the frame 12 (and therefore the valve 10) can be curled into a radially compressed state on a delivery catheter and then expanded in the patient's body by an inflatable balloon or other suitable expansion mechanism. When constructed of a self-expanding material, the frame 12 (and therefore the valve 10) can be curled into a radially compressed state and be restrained in a compressed state by being inserted into a sheath or equivalent mechanism of a delivery catheter. Once in the body, the valve can be advanced from the delivery sheath, allowing the valve to expand to its functional size.

[0049] Suitable plastically expandable materials that can be used to form the frame 12 include, but are not limited to, stainless steel, nickel-based alloys (e.g., cobalt-chromium alloy or nickel-cobalt-chromium alloy), polymers, or combinations thereof. In certain embodiments, the frame 12 is made of a nickel-cobalt-chromium-molybdenum alloy, such as MP35N. TM (Trade name of SPS Technologies), which is equivalent to UNS R30035 (covered by ASTM F562-02). MP35N TMMP35N / UNS R30035 contains, by weight, 35% nickel, 35% cobalt, 20% chromium, and 10% molybdenum. It has been found that using MP35N to form the frame 12 provides structural advantages over stainless steel. Specifically, when MP35N is used as the frame material, less material is required to achieve the same or better radial and compressive force resistance, fatigue resistance, and corrosion resistance. Furthermore, because less material is required, the crimp profile of the frame can be reduced, thereby providing a lower-profile valve assembly for percutaneous delivery to a treatment site within the body.

[0050] Reference Figure 3 and Figure 4 In the illustrated embodiment, the frame 12 includes a lower first row I of angled struts 22 arranged end-to-end and extending circumferentially at the inflow end of the frame; a second row II of circumferentially extending angled struts 24; a third row III of circumferentially extending angled struts 26; a fourth row IV of circumferentially extending angled struts 28; and a fifth row V of circumferentially extending angled struts 32 at the outflow end 56 of the frame. A plurality of substantially straight, axially extending struts 34 can be used to interconnect the first row I of struts 22 with the second row II of struts 24. The fifth row of angled struts 32 is connected to the fourth row IV of angled struts 28 via a plurality of axially extending window frame portions 30 (which define commissure windows 20) and a plurality of axially extending struts 31. Each axial strut 31 and each frame portion 30 extends from a position defined by the meeting point of the lower ends of two angled struts 32 to another position defined by the meeting point of the upper ends of two angled struts 28.

[0051] Each commissure window frame portion 30 mounts a corresponding commissure 58 of the leaflet structure 14. As can be seen, each frame portion 30 is fixed at its upper and lower ends to adjacent rows of struts to provide a robust configuration that enhances fatigue resistance under cyclic loading of the valve compared to known cantilever struts used to support the commissures of the leaflet structure. This configuration enables the thickness of the frame wall to be reduced to achieve a smaller crimped diameter of the valve. In certain embodiments, the frame 12 ( Figure 3 ) has a thickness T of about 0.48 mm or less.

[0052] 1 and 2. The struts and frame portions of the frame collectively define a plurality of openings of the frame. At the inflow end of the frame 12, struts 22, 24, and 34 define a lower row of cells that define openings 36. A second row of struts 24, a third row of struts 26, and a fourth row of struts 28 define two intermediate rows of cells that define openings 38. A fourth row of struts 28 and a fifth row of struts 32, together with the frame portion 30 and struts 31, define an upper row of cells that define openings 60. Openings 60 are relatively large and are sized to allow a portion of the leaflet structure 14 to protrude or bulge into and / or through openings 60 when the frame 12 is curled so as to minimize the curl profile.

[0053] like Figure 4 As shown, the lower ends of struts 31 are connected to two struts 28 at nodes or joints 44, and the upper ends of struts 31 are connected to two struts 32 at nodes or joints 46. The thickness of struts 31 can be less than the thickness of joints 44, 46. Joints 44, 46, together with joints 64 (each joint connecting two adjacent struts 32), prevent the opening 60 from being completely closed when the frame 12 is in the crimped state. Therefore, the geometry of struts 31 and joints 44, 46 and 64 helps to create sufficient space in the opening 60 in the crimped state to allow a portion of the leaflet to protrude outward (i.e., bulge) through the opening. This allows the valve to be crimped to a relatively smaller diameter than if all the leaflet material were confined within the crimped frame.

[0054] The frame 12 is configured to prevent or at least minimize possible over-expansion of the valve at a predetermined balloon pressure, particularly at the outflow end of the frame supporting the leaflet structure 14. In one aspect, the frame is configured to have relatively large angles 42a, 42b, 42c, 42d, 42e between the struts. The larger the angle, the greater the force required to open (expand) the frame. In this way, the angles between the struts of the frame can be selected to limit the radial expansion of the frame at a given opening pressure (e.g., the inflation pressure of the balloon). In particular embodiments, these angles are at least 110 degrees or greater when the frame is expanded to its functional size, and more particularly, these angles are at least 120 degrees or greater when the frame is expanded to its functional size. U.S. Patent Publication No. 2012 / 0123529 further describes other configurations of the frame 12 and frames that can be incorporated into prosthetic heart valves.

[0055] like Figures 1 to 2As shown, the skirt assembly 15 can include an inner skirt 16 located inside the frame 12 and an outer skirt 18 located outside the frame 12. The outer skirt 18 can include a plurality of circumferentially spaced extensions or protrusions 66 and recesses 68 between adjacent protrusions formed along the outflow edge (the upper edge in the illustrated embodiment) of the outer skirt. In other embodiments, the outer skirt 18 can have a straight outflow edge without any protrusions or recesses.

[0056] The inflow (lower) edge and the outflow (upper) edge of the outer skirt 18 can be secured to the frame 12 and / or the inner skirt 16 by, for example, heat bonding, adhesives, and / or suturing. As shown in the illustrated embodiment, the protrusions 66 along the outflow edge of the outer skirt 18 can be secured to the struts of the frame with sutures 70, while the recesses 68 between adjacent protrusions can be unattached to the frame 12 and the inner skirt 16. The outer skirt 18 serves as a sealing member for the prosthetic valve 10 by sealing against the tissue of the native valve annulus, thereby helping to reduce paravalvular leakage through the prosthetic valve 10.

[0057] In some embodiments, as Figures 1 to 2 As shown, when the prosthetic valve 10 is in a radially expanded configuration, the outer skirt 18 can be configured to extend radially outward from the frame 12. Alternatively, the outer skirt 18 can be configured to form a tight fit with the frame 12 so that when the prosthetic valve 10 is in a radially expanded configuration, the outer skirt abuts the outer surface of the frame 12. The outer skirt 18 can be formed from any of a variety of synthetic materials or natural tissues (e.g., pericardial tissue). Suitable synthetic materials include any of a variety of biocompatible fabrics (e.g., PET fabrics) or non-fabric membranes, including any material disclosed below for the reinforcement layer 88 of the inner skirt 16. Further details of the outer skirt 18 are also disclosed in U.S. Patent Publication US2012 / 0123529.

[0058] like Figures 1 to 2 As further shown, the inner skirt 16 in the illustrated embodiment extends from the inlet end 54 of the frame to the fourth row IV angled struts 28. In other embodiments, the inner skirt 16 can extend from the inlet end 54 of the frame to a position shorter than the fourth row IV struts (e.g., to the second row II struts or the third row III struts), or the inner skirt can extend the entire height of the frame 12 (e.g., from the inlet end 54 to the outlet end 56). In alternative embodiments, the inner skirt 16 can be positioned and / or sized to extend at a different height than the fourth row IV struts of the frame 12. Figures 1 to 2 For example, in some embodiments, the inflow end of the inner skirt 16 can be axially spaced from the inlet end 54 of the frame 12 .

[0059] Although the inner skirt 16 is generally tubular or cylindrical in shape (forming a complete circle in a cross-sectional profile in a plane perpendicular to the longitudinal axis of the valve), the inner skirt 16 need not extend 360 degrees in a circumferential direction along the inner surface of the frame 12. In other words, the inner skirt 16 can have a cross-sectional profile (in a plane perpendicular to the axis of the lumen of the valve) that is not a complete circle. The inner skirt 16 can first be formed as a flat strip and then formed into an annular shape by coupling the opposing edge portions together (e.g., by sewing, heat bonding, and / or adhesives). Alternatively, the inner skirt 16 can be formed directly into an annular shape, for example, by constructing the inner layer 16 on a cylindrical core shaft as described below.

[0060] Reference Figure 5 , the inner skirt 16 has a first side 72 defining an inner surface of the inner skirt and a second side 74 defining an outer surface of the inner skirt 16. As described more fully below, the frame-facing side 74 of the inner skirt 16 can have one or more windows or openings through which the otherwise enclosed fabric layer is exposed. Sutures can be passed through the fabric layer of the inner skirt 16 at those windows to secure the inner skirt 16 to the frame 12. For illustrative purposes, Figure 5 The outer skirt 18 is omitted.

[0061] When the inner skirt 16 is mounted to the frame 12, the first side 72 of the inner skirt 16 faces inwardly toward the leaflet structure 14 located inside the prosthetic valve 10, and the second side 74 of the inner skirt 16 faces outwardly toward the inner surface of the frame 12. In certain embodiments, the inner skirt 16 may include a reinforcement layer 88 sandwiched between a first covering member 84 and a second covering member 86. In a representative embodiment, the reinforcement layer 88 may be a fabric layer. The first covering member 84 and the second covering member 86 may also be referred to as encapsulation layers and form the inner and outer layers, respectively, of the illustrated inner skirt 16. In certain embodiments, the inner surface of the reinforcement layer 88 may be completely covered by the first covering member 84 on the first side 72, and the outer surface of the reinforcement layer 88 may be partially covered by the second covering member 86 on the second side 74, wherein the second covering member 86 defines one or more windows or openings 90 (see Figure 10 ), these windows or openings 90 expose the reinforcement layer 88 on the second side 74.

[0062] The reinforcement layer 88 can reinforce the inner skirt 16 to resist tearing. It can also serve as an anchoring layer for suturing the inner skirt 16 to the frame 12 and for supporting the pointed edge portions of the leaflets 40, as described more fully below. In addition, when in the expanded configuration, the reinforcement layer 88, in cooperation with the encapsulating layers 84, 86, can help reduce (or prevent) paravalvular leakage through the prosthetic valve 10.

[0063] In certain embodiments, reinforcing layer 88 can comprise the woven fabric that is woven (woven) by various types of natural or synthetic fibers (or long filament or yarn or ply), and these natural or synthetic fibers include but are not limited to: gauze, PET fiber (for example Dacron), polyester fiber, polyamide fiber etc.In certain embodiments, reinforcing layer 88 can have knitting or braiding structure rather than woven structure.In certain embodiments, reinforcing layer 88 can comprise any one in various nonwoven fabrics, such as felt.The thickness of reinforcing layer 88 can change, but can be less than 6 mils (mil), and ideally less than 4 mils, even more ideally be about 2 mils.

[0064] Alternatively, the reinforcement layer 88 may include one or more layers or films formed from any of a variety of semi-crystalline polymer materials or thermoplastics having aligned or partially aligned (e.g., parallel) molecular chains. Such materials may exhibit anisotropic mechanical properties, such as increased mechanical strength along the longitudinal direction of the molecular chains. Suitable semi-crystalline polymer materials may include, for example, PTFE, PET, polypropylene, polyamide, polyetheretherketone (PEEK), etc., a layer or film of which may be located between and encapsulated by the encapsulating layers 84, 86 to reinforce the inner skirt 16. Unless otherwise noted, in the following description, a fabric layer is described as an exemplary reinforcement layer for illustrative purposes, but it should be understood that a non-woven layer having a sufficiently high tensile strength may also be used as a reinforcement layer.

[0065] The encapsulating layers 84, 86 can be made of any suitable biocompatible material. Ideally, the encapsulating layers 84, 86 include a material that is relatively less abrasive than the fabric layer to reduce wear on the leaflet 40. The encapsulating layers 84, 86 can include, for example, a film or membrane formed from a non-woven fiber or non-fibrous material. The biocompatible material used to form the layers 84, 86 can be a non-absorbable polymer material (i.e., a material that will not dissolve once implanted in the body), and the material can be elastic. In addition, any encapsulating layer 84, 86 can have a porous microstructure that promotes ingrowth of surrounding tissue to help secure the prosthetic valve 10 in the body cavity.

[0066] Examples of encapsulating layer materials include, but are not limited to, ePTFE, unexpanded porous PTFE, polyester or expanded PTFE yarn, PTFE, ultra-high molecular weight polyethylene (UHMWPE), other polyolefins, composite materials (such as ePTFE with PTFE fibers, or UHMWPE membrane with embedded UHMWPE fibers), polyimide, silicone, polyurethane, hydrogel, fluoroethyl polypropylene (FEP), polypropylamine fluoride (PFA), other related fluorinated polymers, or various combinations of any of these materials. In certain embodiments, the encapsulating layers 84, 86 can be formed by respective tubes made of a suitable polymeric material (e.g., ePTFE tube or UHMWPE tube) that can bond to each other when subjected to a heat treatment. In some embodiments, the encapsulating layers 84, 86 can be formed of the same type of material, however, different materials can be used to form the encapsulating layers depending on the specific application.

[0067] Microporous ePTFE tubes can be manufactured using a number of well-known methods. Expanded PTFE is typically produced by mixing granular, dry polytetrafluoroethylene resin with a liquid lubricant to form a viscous slurry. The mixture can be poured into a mold, typically a cylindrical mold, and compressed to form a cylindrical billet. The billet can then be extruded through an extrusion die into a tubular or sheet-like structure, known in the art as an extrudate. The extrudate contains the extruded PTFE-lubricant mixture, known as "wet PTFE." Wet PTFE has a microstructure of agglomerated, bonded PTFE resin particles in a highly crystalline state. After extrusion, the wet PTFE can be heated to a temperature below the flash point of the lubricant to volatilize a substantial portion of the lubricant from the PTFE extrudate. The resulting PTFE extrudate, free of a substantial portion of the lubricant, is known in the art as dried PTFE. The dried PTFE can then be expanded uniaxially, biaxially, or radially using suitable mechanical equipment known in the art. Expansion is typically performed at an elevated temperature, for example, above room temperature but below 327°C, the crystalline melting point of PTFE. Uniaxial, biaxial, or radial expansion of dry PTFE causes the coalesced, bonded PTFE resin to form fibrils emanating from nodes (coalesced PTFE regions), wherein the fibrils are oriented parallel to the axis of expansion. Once expanded, dry PTFE is referred to as expanded PTFE ("ePTFE") or microporous PTFE.

[0068] UHMWPE is made from very long polyethylene chains with molecular weights in the millions, typically between 2 and 6 million. It is highly resistant to corrosive chemicals, has very low moisture absorption, and a very low coefficient of friction. It is self-lubricating and highly wear-resistant. UHMWPE is processed using compression molding, ram extrusion, gel spinning, and sintering. UHMWPE is commercially available in powder, sheet or rod form, and fiber form.

[0069] The encapsulating layers 84 and 86 can be formed in a variety of ways. For example, in one example, an electrospinning process can be used to form the encapsulating layers 84 and 86, which uses electricity to pull a charged line of a polymer solution or polymer melt until the fiber diameter is on the order of several hundred nanometers. In another example, centrifugal spinning technology can be used to form the encapsulating layers 84 and 86. In centrifugal spinning, the spinning solution is placed in a rotating spinning head. When the rotation speed reaches a critical value, the centrifugal force overcomes the surface tension of the spinning solution, thereby ejecting a liquid jet from the nozzle tip of the spinning head. The jet then undergoes a stretching process and is eventually deposited on a collector to form solidified nanofibers. In another example, the encapsulating layers 84 and 86 can be formed using atmospheric plasma spraying (APS) technology, which is a special variant of the thermal spraying process. APS uses an electric arc to ionize a flowing process gas, and can control the hot air flow to melt a very wide range of powder raw materials, thereby applying high-quality coatings to the target object. In other embodiments, the encapsulation layers 84, 86 may be formed using any other suitable method, including, for example, dipping, spraying, or melt spinning. For example, either of the encapsulation layers 84, 86 may be formed by dipping the fabric layer 88 into a liquefied polymer material and then allowing the liquefied polymer material to solidify.

[0070] Figures 6 to 10 An exemplary process for forming the inner skirt 16 is shown. Although the use of electrospinning is described below, this is exemplary in nature and is not intended to be limiting. It should be understood that other processes for depositing the polymer layer may also be used, such as centrifugal spinning, APS, dip coating, and other processes as described above.

[0071] First, if Figure 6 As depicted, the first covering member 84 comprising the first coating material can be deposited circumferentially around the outer surface of cylindrical mandrel 100 by electrospinning (or using other techniques). As known in the art, electrospinning systems can include a spinneret for extruding a polymer solution or a polymer melt to form a fiber. In order to deposit the first covering member 84 on mandrel 100, the electrospinning system can be configured to rotate the fiber extrusion spinneret around mandrel 100 in a circular motion. Alternatively, the fiber extrusion spinneret can be configured to be stationary, and mandrel 100 is placed in front of the spinneret and rotates around its longitudinal axis.

[0072] Second, if Figure 7As depicted, the fabric layer 88 can be placed on the first covering member 84. The fabric layer 88 can be in the form of a piece of fabric material that is tightly wrapped around the first covering member 84. For example, as depicted above, the fabric layer 88 can have a woven structure that includes lines of warp fibers and weft fibers extending perpendicular to each other. In alternative embodiments, the fabric layer 88 can also be deposited on the first covering member 84. For example, as described above, the fabric layer 88 can include a non-woven fabric, which itself can be formed by electrospinning and ideally has a relatively higher tensile strength than layers 84, 86. In another example, the layer 88 can be a pre-formed woven material that is wrapped around the first covering member 84. In another example, the layer 88 can be formed by weaving one or more yarns or filaments around the first covering member 84 to form a woven layer around the first covering member.

[0073] Third, if Figure 8 As depicted, one or more masks 92 may be placed on the fabric layer 88 at selected areas 94 of the fabric. Figure 9 As depicted, a second covering member 86 comprising a second coating material may be deposited on the masked fabric layer 88 by electrospinning (or using other techniques). Figure 10 As depicted, mask 92 is removed after deposition of second cover member 86. Thus, one or more windows 90 corresponding to selected areas 94 are created such that windows 90 expose fabric layer 88 underneath.

[0074] exist Figures 8 and 9 In the illustrated embodiment, the mask 92 can temporarily cover selected areas 94 of the fabric layer 88 and prevent these selected areas 94 from being deposited with the second coating material of the second cover member 86. Alternatively, the selected areas 94 can be functionally masked without the application of a physical mask 94. For example, the relative movement and operation (e.g., activation and / or deactivation) of the fiber extrusion spinneret relative to the mandrel 100 can be programmed such that the second coating material of the second cover member 86 can only be deposited on portions of the fabric layer 88 outside of the selected areas 94.

[0075] exist Figures 8 and 9 In the embodiment depicted in FIG, three annular bands of mask 92 are shown, corresponding to three selected areas 94 along the outer periphery of fabric layer 88. As a result, after removing mask 92, three annular windows 90 are created, as shown in FIG. Figure 10As depicted. In other embodiments, any of the masks 92 can have a non-annular shape so that the corresponding selected area 94 and the resulting window 90 do not completely surround the fabric layer 88. For example, any of the masks 92 can have a customized shape at a customized location to create a customized window 90. Furthermore, although three windows 90 are shown in the illustrated embodiment, the inner skirt can be formed with a fewer or greater number of windows, and these windows can be positioned anywhere along the skirt. For example, in some embodiments, the inner skirt can be formed with one or more rows of circumferentially extending windows, wherein each row includes a plurality of circumferentially spaced windows. In other embodiments, one or more windows can be formed along the inlet edge and / or outlet edge of the inner skirt.

[0076] Although not shown, it should be understood that an anchoring mechanism may be provided to temporarily secure the position of each layer during each of the above steps. As a non-limiting example, a layer of PTFE tape may be wrapped around one or both ends of the second cover member 86 to help secure the orientation of the second cover member 86 to the underlying layer of the assembly and the mandrel 100 during subsequent processing.

[0077] In a representative embodiment, the fabric layer 88 has a plurality of openings that allow the first cover member 84 and the second cover member 86 to be fused together through those openings. In one example, the openings in the fabric layer 88 can be created by weaving, braiding, or knitting fibers or yarns to form the fabric layer. In another example, the fabric layer 88 can have a non-woven porous structure with openings. In another example, such as when a non-woven fabric (e.g., felt) is used to form the fabric layer, the openings in the fabric layer 88 can be formed by cutting (e.g., laser cutting) openings in the fabric layer.

[0078] In one exemplary embodiment, the fusing of the first cover member 84 and the second cover member 86 through the openings in the fabric layer 88 can occur simultaneously with the deposition of the second cover member 86 onto the masked fabric layer 88. When the second coating material extruded from the spinneret is deposited onto the fabric layer 88 to form the second cover member 86, some of the second coating material can penetrate through the openings in the fabric layer 88 and fuse with the fibers in the first cover member 84.

[0079] In other embodiments, the fusion between the first cover member 84 and the second cover member 86 may occur after the second cover member 86 is deposited on the masked fabric layer 88. For example, Figure 10The assembly shown can undergo an encapsulation process, whereby the assembly is subjected to heat and / or pressure to bond the first and second cover members 84, 86 to each other through the openings in the fabric layer 88. Furthermore, the fabric layer 88 can be shorter in axial length than the first and second cover members 84, 86 to facilitate bonding of the first and second cover members 84, 86 at their respective ends to encapsulate the fabric layer 88 therebetween. Similar encapsulation processes are described in U.S. Patent Publications US2014 / 0209238 and US2016 / 0317305.

[0080] In an exemplary embodiment, ePTFE may be used as the first coating material for depositing the first covering member 84 and / or the second coating material for depositing the second covering member 86. Alternatively, other materials may be used, such as UHMWPE, polyurethane composites, or any other non-absorbable polymer materials described above. The inner skirt 16 may ideally have a laminated structure in which the fabric layer 88 is sandwiched between two fused layers (the first covering member 84 and the second covering member 86). In some embodiments, the same material may be used to deposit the first covering member 84 and the second covering member 86. Due to the interlayer fusion or bonding, the first covering member 84 and the second covering member 86 may be merged together, effectively creating a single structure (i.e., no physical interlayer boundary) in which the fabric layer 88 is encapsulated. The density of the first covering member 84 may be the same as or different from the density of the second covering member 86. In other embodiments, the first coating material used to deposit the first covering member 84 may be different from the second coating material used to deposit the second covering member 86.

[0081] After the first and second covering members 84, 86 are securely fused together to encapsulate the fabric layer 88, the inner skirt 16 can be removed from the core shaft 100. One or both ends of the inner skirt 16 can be trimmed to achieve the desired height of the inner skirt. The inner skirt 16 can then be mounted to the frame 12.

[0082] although Figures 6 to 10 The above description shows a process for forming an annular inner skirt 16, but it should be understood that the same process can be used to form the outer skirt 18. In addition, as described above, the inner skirt 16 can be first formed into a flat strip and then formed into an annular shape by coupling its two opposing edges together. To form the flat strip, the first and second cover members 84, 86, and the fabric layer 88 can be constructed on a flat substrate instead of the cylindrical mandrel 100 described above.

[0083] While the above-described process uses a mask to create windows 90 in the second cover member 86 of the inner skirt 16, it should be understood that other methods can be used to create those windows 90. For example, the second cover member 86 can first be deposited over the entire surface of the fabric layer 88. Selected areas 94 on the second cover member 86 can then be located and removed, for example, by laser cutting, chemical etching, or other means. As a result, windows 90 can be created in the selected areas 94 on the second cover member 86, thereby exposing the underlying fabric layer 88 therein. In another example, the second cover member 86 can be prefabricated so that the second coating material is absent in the selected areas 94. The prefabricated second cover member 86 can then be wrapped around the fabric layer 88. As a result, the fabric layer 88 can be exposed through the windows 90 created in the selected areas 94. The assembly (first cover member 84, fabric layer 88, and second cover member 86) can then be subjected to a heat and / or pressure-based encapsulation process as described above, resulting in the first and second cover members 84, 86 being bonded to each other.

[0084] The inner skirt 16 can be sewn to the frame 12 at the location of the windows 90. For example, the inner skirt 16 can be placed inside the frame 12. The windows 90 can be positioned so as to generally correspond to the first row of struts 22, the second row of struts 26, and the third row of struts 28, respectively, although other configurations can be used. The inner skirt 16 can also be secured to the struts in the first row of struts, the third row of struts, and the fourth row of struts by stitching that surrounds the struts and extends through the fabric layer 88 at the location of the windows 90, as shown below in conjunction with Figures 11 to 13 Because the windows in the illustrated embodiment extend continuously around the entire periphery of the inner skirt, a continuous circumferentially extending whip stitch can be formed along each row of struts and in the fabric layer 88 at each window 90 .

[0085] As described above, the windows 90 can be created at selected locations and can have any of a variety of shapes, thereby allowing the inner skirt to be sewn to the frame at different locations. For example, as described above, the inner skirt can be formed with rows of circumferentially spaced windows, which can allow, for example, individual sutures or stitches to be placed at selected portions of the inner skirt that are more susceptible to tension or compression, which do not extend continuously along the entire row of struts.

[0086] Figures 11 to 13 An exemplary method of sewing the inner skirt 16 to the frame 12 is shown. Figure 11 A cross-sectional view of a portion of the inner skirt 16 is shown having a first side 72 and a second side 74. As described above, the inner skirt 16 has an encapsulated fabric layer 88 sandwiched between a first cover member 84 on the first side 72 and a second cover member 86 on the second side 74. Figure 11 Also depicted is a window 90 on the second cover member 86 of the inner skirt 16, which exposes the underlying fabric layer 88. When the same material is used to form the encapsulation layers 84, 86 that can be fused or bonded together to form a single, unitary structure of the encapsulation fabric, there may be no interlayer boundary (as shown by the dotted lines). In the depicted embodiment, the fabric layer 88 is shown as having a woven structure including woven filaments, fibers, or yarns 96. The woven filaments 96 ideally have sufficient strength to serve as anchors to hold sutures 98, as described below.

[0087] Figure 12 The diagram schematically illustrates how a suture 98 is threaded between the fabric layer 88 and the first covering member 84 through the window 90. In the depicted embodiment, the suture 98 is attached to a needle 102. The tip 108 of the needle 102 is ideally blunt. By sliding the needle 102 from the second side 74 and through the window 90 while applying a light force at the needle tip 108, the first covering member 84 can be slightly pushed away from the fabric layer 88, thereby creating space for the needle 102 to be inserted between the first covering member 84 and the fabric layer 88. As shown, the needle 102 and the attached suture 98 can be slid into the fabric layer 88 from the first end 104 of the window 90, passed behind one or more filaments 96 exposed by the window 90 (e.g., 96a and 96b), and then slid out of the fabric layer 88 at the second end 106 of the window 80. In this manner, the suture 98 does not extend through the entire thickness of the inner skirt 16. In some embodiments, the first covering member 84 may not be separated from the fabric layer 88 by the insertion needle 102 (e.g., Figure 12 ), in which case the needle 102 and attached suture 98 may partially penetrate the thickness of the first covering member 84 but not extend through the entire thickness of the inner skirt.

[0088] Figure 13 Schematically, the fabric layer 88 of the inner skirt 16 is sewn to the adjacent struts 22 of the frame 12. Ideally, the first side 72 of the inner skirt 16 faces inwardly toward the leaflet structure 14 located inside the prosthetic valve 10, and the second side 74 of the inner skirt 16 faces outwardly toward the frame 12. By passing a needle 102 and an attached suture 98 through the window 90 between the fabric layer 88 and the first covering member 84, the woven filaments 96 (e.g., 96a and 96b) between the first end 104 and the second end 106 of the window 80 can collectively serve as an anchor to secure the suture 98. The suture 98 can then be wrapped around the adjacent struts 22, thereby securing those woven filaments (e.g., 96a and 96b) to the adjacent struts 22. Thus, the inner skirt 16 can be securely attached to the frame 12. Figure 13For purposes of illustration, support 22 is depicted. It will be appreciated that the inner skirt 16 may be sewn to the other supports (eg, 26, 28, 32) of the frame in a similar manner.

[0089] As described above, the fabric layer 88 can also have a non-woven structure without a distinct weave 96. In this case, the suture 98 can be attached to a needle having a pointed tip. The needle can be used to pierce the fabric layer 88 and pass the suture 98 through the fabric layer. In this way, the portion of the fabric layer 88 between the first end 104 and the second end 106 of the window 90 can serve as an anchor for securing the suture 98, which in turn secures that portion of the fabric to the adjacent support 22. As a result, the inner skirt 16 can be securely attached to the frame 12.

[0090] Because suture 98 is routed between first covering member 84 and fabric layer 88, it is not exposed on first side 72 of inner skirt 16. In other words, suture 98 is covered by first covering member 84. The inner surface of the fabric layer is also covered by the first covering member. Thus, wear of the leaflets 40 caused by repeated contact between the leaflets 40 and inner skirt 16, and between the leaflets 40 and suture 98, during the operating cycle of prosthetic valve 10 is avoided. Ideally, inner skirt 16 is sutured to frame 12 only at one or more windows 90 in second covering member 86, thereby avoiding contact between the movable portions of leaflets 40 and suture 98. Furthermore, first covering member 84 ideally covers the entire extent of the inner surface of the fabric layer, or at least that portion of the fabric layer that would otherwise come into contact with the movable portions of the leaflets during the operating cycle of the prosthetic valve. In some embodiments, suture 98 may be threaded through the entire thickness of the inner skirt, such as at locations on the inner skirt that would not come into contact with the movable portions of the leaflets.

[0091] As described above, the leaflets 40 can be secured to each other on their adjacent sides to form commissures 58. Each commissure 58 can be secured to a corresponding commissure window 20 of the frame 12, as described in U.S. Patent Publication No. 2012 / 0123529. The inflow or pointed edge 52 of the leaflet 40 can be sutured to the inner skirt 16 along a suture guide that tracks the curvature of the scalloped inflow edge of the leaflet structure. The fabric layer 88 can provide the strength required to hold the suture. Any suitable suture, such as an Ethibond suture, can be used to secure the leaflet 40 to the fabric layer 88 of the inner skirt.

[0092] In some embodiments, the inflow edges 52 of the leaflets 40 are secured to the inner skirt 16 before the inner skirt 16 is mounted to the frame. After the leaflets 40 are secured to the inner skirt 16, the inner skirt is secured to the frame as described above, and the commissures 58 of the leaflets are mounted to the frame. In other embodiments, the inner skirt 16 can be mounted to the frame without the leaflets, after which the inflow edges 52 of the leaflets are then secured to the inner skirt.

[0093] In certain embodiments, the inflow edge 52 of the leaflet 40 can be secured to the inner skirt via a thin PET reinforcement strip (not shown), as disclosed in U.S. Patent No. 7,993,394. As described in U.S. Patent No. 7,993,394, the reinforcement strip can be sutured to the inflow edge of the leaflet. The reinforcement strip and the lower edge of the leaflet can then be sutured to the inner skirt 16. Ideally, the reinforcement strip is secured to the inner surface of the leaflet 40 so that when the leaflet and the reinforcement strip are secured to the inner skirt, the inflow edge 52 of the leaflet is sandwiched between the reinforcement strip and the inner skirt. The reinforcement strip provides a secure suture and protects the pericardial tissue of the leaflet structure from tearing.

[0094] As described above, the outer skirt 18 can be constructed in a similar manner to the inner skirt 16. That is, the outer skirt 18 can also have a reinforcement layer (e.g., a fabric layer 88) sandwiched between the encapsulating layers 84, 86. Similarly, the window 90 can be created in one of the encapsulating layers 84, 86. Since the outer skirt 18 is attached to the exterior of the frame 12, it is ideal that the outer layer 18 is arranged so that the frame 12 faces the side of the outer skirt 18 having the window 90. In this arrangement, the outer skirt 18 can be attached to the frame 12 by sewing the encapsulating fabric layer 88 to the frame 12 through the window 90 facing the frame.

[0095] In another embodiment, the outer skirt 18 can have a fabric layer 88 that is coated with only one of the encapsulation layers 84, 86. When the outer skirt 18 is attached to the frame 12, the outer skirt 18 can be arranged so that the uncoated side of the fabric layer 88 faces inwardly toward the frame 12, so that the outer skirt 18 can be attached to the frame 12 by sewing the exposed fabric layer 88 to the frame 12.

[0096] Alternatively, the outer skirt 18 can include only the fabric layer 88 without any of the encapsulation layers 84, 86. In this way, the outer skirt 18 can be sutured directly to the frame 12. Because the sutures on the outer skirt 18 are not subject to repeated contact due to the moving leaflets 40, the leaflets are less abraded due to the sutures on the outer skirt 18 than the sutures on the inner skirt 16. By eliminating one or both of the encapsulation layers 84, 86, the outer layer 18 can be constructed thinner, thereby reducing the overall profile of the valve 10 when the valve 10 is crimped into a radially compressed state.

[0097] General Notes

[0098] It should be understood that the disclosed embodiments can be suitable for delivering and implanting prosthetic devices in any native valve annulus of the heart (e.g., the pulmonary valve annulus, mitral valve annulus, and tricuspid valve annulus) and can be used with various delivery methods (e.g., retrograde, antegrade, transseptal, transventricular, transatrial, etc.).

[0099] For descriptive purposes, certain aspects, advantages and novel features of embodiments of the present disclosure are described herein. The disclosed methods, apparatus and systems should not be construed as limiting in any way. On the contrary, the present disclosure relates to all novel and non-obvious features and aspects of the various disclosed embodiments, either individually or in various combinations and sub-combinations of each other. The methods, apparatus and systems are not limited to any particular aspect or feature or combination thereof, nor do the disclosed embodiments require the presence of any one or more specific advantages or solutions to problems. The techniques in any example can be used in combination with the techniques described in any one or more of the other examples. In view of the many possible embodiments to which the principles of the disclosed techniques can be applied, it should be recognized that the embodiments shown are preferred examples only and should not be considered as limiting the scope of the disclosed techniques.

[0100] Although the operations of some disclosed embodiments are described in a particular sequential order for ease of presentation, it should be understood that this description includes rearrangement unless the specific language set forth later requires a particular order. For example, in some cases, the operations described in sequence can be rearranged or performed simultaneously. In addition, for simplicity, the accompanying drawings may not show the various ways in which the disclosed methods can be used in conjunction with other methods. In addition, the description sometimes uses terms such as "provide" or "implement" to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms can vary depending on the specific implementation and can be easily discerned by a person of ordinary skill in the art.

[0101] As used in this application and the claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Additionally, the term "including" means "comprising." Furthermore, the terms "coupled" and "connected" generally refer to electrical, electromagnetic, and / or physical (e.g., mechanically or chemically) coupling or connection, and, in the absence of specific language to the contrary, do not preclude the presence of intervening elements between coupled or associated items.

[0102] Directional and other relative references (e.g., inside, outside, up, down, etc.) may be used to facilitate the discussion of the figures and principles herein, but are not intended to be limiting. For example, certain terms such as "inside," "outside," "top," "downward," "inside," "outside," and the like may be used. When dealing with relative relationships, particularly with respect to the embodiments shown, such terms are used to provide some clarity of description where applicable. However, such terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, "upper" can become "lower" simply by turning the object over. However, it is still the same part, and the object is still the same. As used herein, "and / or" means "and" or "or," as well as "and" and "or."

[0103] In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are merely preferred examples of the invention and should not be considered as limiting the scope of the invention. Rather, the scope of the invention is defined by the appended claims. We therefore claim as our invention all that falls within the scope of these claims.

Claims

1. A method for manufacturing an implantable prosthetic valve, comprising: forming a laminate comprising a fabric layer disposed between a first cover member and a second cover member, wherein the second cover member comprises one or more windows at which the fabric layer is exposed; placing the laminate against the annular frame; stitching the laminate to the annular frame by passing a stitch through the fabric layer at the one or more windows of the second covering member and around a portion of the annular frame; and attaching one or more leaflets to the laminate within the annular frame, the leaflets configured to regulate blood flow through the prosthetic valve, wherein the stitching partially penetrates the thickness of the first covering member but does not extend through the entire thickness of the laminate.

2. The method of claim 1 , wherein the laminate includes an annular skirt sized and shaped to cover the opening in the frame to prevent blood from flowing through the opening in the frame.

3. The method of claim 2, wherein the skirt is positioned inside the annular frame. 4 . The method of claim 1 , wherein the first covering member and the second covering member are fused to each other through openings in the fabric layer.

5. The method of claim 1 , wherein the act of forming the laminate comprises: The first covering member is formed by electrospinning, the fabric layer is placed on the electrospun first covering member, and the second covering member is formed on the fabric layer by electrospinning.

6. The method of claim 5, wherein the act of forming the laminate further comprises: Prior to forming the second covering member, one or more areas are masked on the fabric layer so that when the second covering member is formed on the fabric layer, the one or more windows are formed in the second covering member.

7. The method of claim 1 , wherein the act of forming the laminate comprises: Masking one or more areas on at least one side of the fabric layer with a masking material, immersing the fabric layer in a liquefied polymer material, allowing the liquefied polymer material to solidify, and removing the masking material to form the one or more windows in the laminate.

8. The method of claim 2, wherein the one or more windows in the second covering member extend continuously in a circumferential direction around the laminate.

9. The method of claim 1, wherein the first cover member and the second cover member comprise an elastic material.

10. The method of claim 9, wherein the elastic material comprises ePTFE or UHMWPE or polyurethane.

11. The method of claim 1 , wherein the one or more leaflets are attached to the laminate prior to suturing the laminate to the annular frame.

12. The method of claim 1, wherein the one or more leaflets are attached to the laminate after the laminate is sutured to the annular frame.

13. The method of claim 1 , wherein each leaflet has a U-shaped inlet edge such that the inlet edge of the one or more leaflets forms a wavy, scalloped curvature, and wherein the one or more leaflets are sutured to the laminate along a suture guide that tracks the scalloped curvature of the inlet edge.

14. The method of claim 1 , wherein the suture is attached to a needle, and suturing the laminate to the annular frame comprises: The needle is inserted into the fabric layer in a first direction at a first end of the window, passed behind one or more filaments of the fabric layer, and removed from the fabric layer in a second direction at a second end of the window.

15. The method of claim 14, wherein the needle and attached suture extend through a space between the fabric layer and the first covering member.

16. The method of claim 1, wherein the seam does not extend through the entire thickness of the laminate.

17. A method for manufacturing an implantable prosthetic valve, comprising: attaching one or more leaflets to the inner skirt; and attaching the inner skirt to the annular frame; wherein the leaflets are configured to allow blood to flow from an inflow end to an outflow end of the frame and to prevent blood from flowing from the outflow end to the inflow end of the frame; wherein the inner skirt comprises a fabric layer disposed between a first cover member and a second cover member, the second cover member comprising at least one window exposing a portion of the fabric layer; wherein the inner skirt is attached to the annular frame via stitching, the stitching extending through the portion of the fabric layer exposed by the window; wherein the stitching partially penetrates the thickness of the first covering member but does not extend through the entire thickness of the inner skirt.

18. The method of claim 17, wherein the suture is routed between the first covering member and the fabric layer.

19. The method of claim 17, wherein the at least one window comprises one or more annular windows through which the inner skirt is sewn to the annular frame.

20. The method of claim 19, wherein the annular window comprises a first window positioned adjacent the inflow end of the frame, a second window positioned adjacent the outflow end of the frame, and a third window located between the first window and the second window.

21. An implantable prosthetic valve comprising: Ring frame; annular inner skirt; and one or more leaflets attached to the inner skirt; wherein the one or more leaflets are configured to allow blood to flow from an inflow end to an outflow end of the frame and to prevent blood from flowing from the outflow end to the inflow end of the frame; wherein the annular inner skirt comprises a fabric layer disposed between a first cover member and a second cover member, the second cover member comprising at least one window exposing a portion of the fabric layer; wherein the annular inner skirt is attached to the annular frame via stitching, the stitching extending through the portion of the fabric layer exposed by the window; wherein the suture partially penetrates the thickness of the first covering member but does not extend through the entire thickness of the annular inner skirt.

22. The implantable prosthetic valve of claim 21, wherein the suture extends between the first covering member and the fabric layer.

23. The implantable prosthetic valve of claim 21, wherein the window extends continuously around the entire circumference of the annular inner skirt.

24. The implantable prosthetic valve of claim 21, wherein the at least one window comprises a first window positioned adjacent the inflow end of the frame, a second window positioned adjacent the outflow end of the frame, and a third window located between the first and second windows.

25. The implantable prosthetic valve of claim 21, wherein the first and second covering members are fused to each other through the openings in the fabric layer.

26. The implantable prosthetic valve of claim 21, wherein the first covering member comprises a first elastic material and the second covering member comprises a second elastic material different from the first elastic material.

27. The implantable prosthetic valve of claim 21, wherein the first covering member comprises a first elastic material and the second covering member comprises a second elastic material that is the same as the first elastic material.

28. An implantable prosthetic valve according to claim 21, wherein each leaflet has a U-shaped inlet edge, so that the inlet edge of the one or more leaflets forms a wavy fan-shaped curvature, and wherein the one or more leaflets are sutured to the annular inner skirt along a suture guide line that tracks the fan-shaped curvature of the inlet edge.

29. An implantable prosthetic valve comprising: Ring frame; an inner skirt comprising a fabric layer sandwiched between a first cover member and a second cover member; and one or more leaflets attached to the inner skirt; wherein the one or more leaflets are configured to allow blood to flow from an inflow end to an outflow end of the frame and to prevent blood from flowing from the outflow end to the inflow end of the frame; wherein the first covering member faces inwardly toward the one or more leaflets and the second covering member faces outwardly toward the annular frame; wherein the inner skirt is coupled to the annular frame by stitching, the stitching extending through the fabric layer; wherein the suture is covered by the first covering member such that the one or more leaflets cannot directly contact the suture; and wherein the stitching partially penetrates the thickness of the first covering member but does not extend through the entire thickness of the inner skirt.

30. The implantable prosthetic valve of claim 29, wherein the second covering member includes at least one window exposing a portion of the fabric layer, and the suture extends through the portion of the fabric layer exposed by the window.

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