Patent Description:
In a procedure to implant a transcatheter prosthetic heart valve, the prosthetic heart valve is typically positioned in the annulus of a native heart valve and expanded or allowed to expand to its functional size. In order to retain the prosthetic heart valve at the desired location, the prosthetic heart valve may be larger than the diameter of the native valve annulus such that it applies force to the surrounding tissue in order to prevent the prosthetic heart valve from becoming dislodged. In other configurations, the prosthetic heart valve may be expanded within a support structure that is located within the native annulus and configured to retain the prosthetic heart valve at a selected position with respect to the annulus. Over time, relative motion of the prosthetic heart valve and tissue of the native heart valve (e.g., native valve leaflets, chordae tendineae, etc.) in contact with the prosthetic heart valve may cause damage to the tissue. Accordingly, there is a need for improvements to prosthetic heart valves.

International application <CIT> provides a quick-connect heart valve prosthesis that can be quickly and easily implanted during a surgical procedure. The heart valve includes a substantially non-expandable, non-compressible prosthetic valve and a plastically-expandable stent frame, thereby enabling attachment to the annulus without sutures. The prosthetic valve may be a commercially available valve with a sewing ring and the stent frame attached thereto. The stent frame may expand from a conical deployment shape to a conical expanded shape, and may have a cloth covering its entirety as well as a plush sealing flange around its periphery to prevent paravalvular leaking.

Disclosed are coverings for prosthetic heart valves and methods of making and using the same. The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

The present disclosure concerns implantable prosthetic heart valves and methods of making and using such devices. In one aspect, a prosthetic heart valve includes an outer covering having a backing layer and a main cushioning layer disposed on the backing layer such that the cushioning layer is oriented radially outward about the circumference of the valve. The cushioning layer can be soft and compliant in order to reduce damage to native tissues of the heart valve and/or of the surrounding anatomy at the implantation site due to, for example, relative movement or friction between the prosthetic valve and the tissue as the heart expands and contracts. The covering can also include an inflow protective portion and an outflow protective portion to cushion the surrounding anatomy and prevent the native tissue of the heart valve from contacting the apices of the strut members of the frame, thereby protecting the surrounding tissue. In another example, the covering can include an inflow strip member and an outflow strip member secured to the cushioning layer and folded over the apices of the strut members to form the inflow and outflow protective portions.

The disclosed technology can be used in combination with various prosthetic heart valves configured for implantation at various locations within the heart. A representative example is a prosthetic heart valve for replacing the function of the native mitral valve. <FIG> illustrate the mitral valve of the human heart. The mitral valve controls the flow of blood between the left atrium and the left ventricle. After the left atrium receives oxygenated blood from the lungs via the pulmonary veins, the mitral valve permits the flow of the oxygenated blood from the left atrium into the left ventricle. When the left ventricle contracts, the oxygenated blood that was held in the left ventricle is delivered through the aortic valve and the aorta to the rest of the body. Meanwhile, the mitral valve closes during ventricular contraction to prevent any blood from flowing back into the left atrium.

When the left ventricle contracts, the blood pressure in the left ventricle increases substantially, which urges the mitral valve closed. Due to the large pressure differential between the left ventricle and the left atrium during this time, a possibility of prolapse, or eversion of the leaflets of the mitral valve back into the atrium, arises. A series of chordae tendineae therefore connect the leaflets of the mitral valve to papillary muscles located on the walls of the left ventricle, where both the chordae tendineae and the papillary muscles are tensioned during ventricular contraction to hold the leaflets in the closed position and to prevent them from extending back towards the left atrium. This generally prevents backflow of oxygenated blood back into the left atrium. The chordae tendineae are schematically illustrated in both the heart cross-section of <FIG> and the top view of the mitral valve of <FIG>.

A general shape of the mitral valve and its leaflets as viewed from the left atrium is shown in <FIG>. Various complications of the mitral valve can potentially cause fatal heart failure. One form of valvular heart disease is mitral valve leak or mitral regurgitation, characterized by abnormal leaking of blood from the left ventricle through the mitral valve back into the left atrium. This can be caused by, for example, dilation of the left ventricle, which can cause incomplete coaptation of the native mitral leaflets resulting in leakage through the valve. Mitral valve regurgitation can also be caused by damage to the native leaflets. In these circumstances, it may be desirable to repair the mitral valve, or to replace the functionality of the mitral valve with that of a prosthetic heart valve, such as a transcatheter heart valve.

Some transcatheter heart valves are designed to be radially crimped or compressed to facilitate endovascular delivery to an implant site at a patient's heart. Once positioned at a native valve annulus, the replacement valve is then expanded to an operational state, for example, by an expansion balloon, such that a leaflet structure of the prosthetic heart valve regulates blood flow through the native valve annulus. In other cases, the prosthetic valve can be mechanically expanded or radially self-expand from a compressed delivery state to the operational state under its own resiliency when released from a delivery sheath. One example of a prosthetic heart valve is illustrated in <FIG>. A transcatheter heart valve with a valve profile similar to the prosthetic valve shown in <FIG> is the Edwards Lifesciences SAPIEN XT™ valve. The prosthetic valve <NUM> in <FIG> has an inflow end <NUM> and an outflow end <NUM>, includes a frame or stent <NUM>, and a leaflet structure <NUM> supported inside the frame <NUM>. A skirt <NUM> can be attached to an inner surface of the frame <NUM> to form a more suitable attachment surface for the valve leaflets of the leaflet structure <NUM>.

The frame <NUM> can be made of any body-compatible expandable material that permits both crimping to a radially collapsed state and expansion back to the expanded functional state illustrated in <FIG>. For example, where the prosthetic valve is a self-expandable prosthetic valve that expands to its functional size under its own resiliency, the frame <NUM> can be made of Nitinol or another self-expanding material. Alternatively, the prosthetic valve can be a plastically expandable valve that is expanded to its functional size by a balloon or another expansion device, in which case the frame can be made of a plastically expandable material, such as stainless steel or a cobalt chromium alloy. Other suitable materials can also be used.

The frame <NUM> can comprise an annular structure having a plurality of vertically extending commissure attachment posts <NUM>, which attach and help shape the leaflet structure <NUM> therein. Additional vertical posts or strut members <NUM>, along with circumferentially extending strut members <NUM>, help form the rest of the frame <NUM>. The strut members <NUM> of the frame <NUM> zig-zag and form edged crown portions or apices <NUM> at the inflow and outflow ends <NUM>, <NUM> of the valve <NUM>. Furthermore, the attachment posts <NUM> can also form edges at one or both ends of the frame <NUM>.

In prosthetic valve <NUM>, the skirt <NUM> is attached to an inner surface of the valve frame <NUM> via one or more threads <NUM>, which generally wrap around to the outside of various struts <NUM>, <NUM>, <NUM> of the frame <NUM>, as needed. The skirt <NUM> provides a more substantive attachment surface for portions of the leaflet structure <NUM> positioned closer to the inflow end <NUM> of the valve <NUM>.

<FIG> and <FIG> show side cross-sectional views of different anchors that can be used to facilitate implantation of the valve <NUM> at the mitral position of a patient's heart. As shown in <FIG> and <FIG>, a left side of a heart <NUM> includes a left atrium <NUM>, a left ventricle <NUM>, and a mitral valve <NUM> connecting the left atrium <NUM> and the left ventricle <NUM>. The mitral valve <NUM> includes anterior and posterior leaflets <NUM> that are connected to an inner wall of the left ventricle <NUM> via chordae tendineae <NUM> and papillary muscles <NUM>.

In <FIG>, a first anchoring device includes a flexible ring or halo <NUM> that surrounds the native leaflets <NUM> of the mitral valve <NUM> and/or the chordae tendineae <NUM>. The ring <NUM> pinches or urges portions of the leaflets inwards, in order to form a more circular opening at the mitral position, for more effective implantation of the prosthetic valve <NUM>. The valve prosthesis <NUM> is retained in the native mitral valve annulus <NUM> by the ring anchor <NUM>, and can be delivered to the position shown, for example, by positioning the valve <NUM> in the mitral annulus <NUM> while the valve <NUM> is crimped, and then expanding the valve <NUM> once it is positioned as shown in <FIG>. Once expanded, the valve <NUM> pushes outwardly against the ring anchor <NUM> to secure the positions of both the valve <NUM> and the ring anchor <NUM>. An undersized ring anchor <NUM> with an inner diameter that is slightly smaller than the diameter of the prosthetic valve <NUM> in its expanded state can be used, to provide stronger friction between the parts, leading to more secure attachment. As can be seen in <FIG>, at least a portion of the native mitral valve leaflets <NUM> and/or a portion of the chordae tendineae <NUM> are pinched or sandwiched between the valve <NUM> and the ring anchor <NUM> to secure the components to the native anatomy.

<FIG> is similar to <FIG>, except instead of a ring anchor <NUM>, a helical anchor <NUM> is utilized instead. The helical anchor <NUM> can include more coils or turns than the ring anchor <NUM>, and can extend both upstream and downstream of the mitral valve annulus <NUM>. The helical anchor <NUM> in some situations can provide a greater and more secure attachment area against which the valve <NUM> can abut. Similar to the ring anchor <NUM> in <FIG>, at least a portion of the native mitral valve leaflets <NUM> and/or the chordae <NUM> are pinched between the valve <NUM> and the helical anchor <NUM>. Methods and devices for implanting helical anchors and prosthetic valves are described in <CIT>, and <CIT>.

<FIG> illustrates another helical anchor <NUM> that can be used in combination with any of the prosthetic valves described herein. The anchor <NUM> can be configured as a coil having a central region <NUM>, a lower region <NUM>, and an upper region <NUM>. The lower region <NUM> includes one or more turns in a helical arrangement that can be configured to encircle or capture the chordae tendineae and/or the leaflets of the mitral valve. The central region <NUM> includes a plurality of turns configured to retain the prosthetic valve in the native annulus. The upper region <NUM> includes one or more turns, and can be configured to keep the anchor from being dislodged from the valve annulus prior to implantation of the prosthetic valve. The upper region <NUM> can be positioned over the floor of the left atrium, and can be configured to keep the turns of the central region <NUM> positioned high within the mitral apparatus.

The anchor <NUM> also includes an extension portion <NUM> positioned between the central region <NUM> and the upper region <NUM>. Alternatively, the extension portion <NUM> can be positioned, for example, wholly in the central region <NUM> (e.g., at an upper portion of the central region) or wholly in the upper region <NUM>. The extension portion <NUM> includes a part of the coil that extends substantially parallel to a central axis of the anchor. Alternatively, the extension portion <NUM> can be angled relative to the central axis of the anchor. The extension portion <NUM> can serve to space the central region <NUM> and the upper region <NUM> apart from one another in a direction along the central axis so that a gap is formed between the atrial side and the ventricular side of the anchor.

The extension portion <NUM> of the anchor is intended to be positioned through or near the native valve annulus, in order to reduce the amount of the anchor that passes through, pushes, or rests against the native annulus and/or the native leaflets when the anchor is implanted. This can reduce the force applied by the anchor on the native mitral valve and reduce abrasion of the native leaflets. In one arrangement, the extension portion <NUM> is positioned at and passes through one of the commissures of the native mitral valve. In this manner, the extension portion <NUM> can space the upper region <NUM> apart from the native leaflets of the mitral valve to prevent the upper region <NUM> from interacting with the native leaflets from the atrial side. The extension portion <NUM> also elevates the upper region <NUM> such that the upper region contacts the atrial wall above the native valve, which can reduce the stress on and around the native valve, as well as provide for better retention of the anchor.

The anchor <NUM> can further include one or more openings configured as through holes <NUM> at or near one or both of the proximal and distal ends of the anchor. The through holes <NUM> can serve, for example, as suturing holes for attaching a cover layer over the coil of the anchor, or as an attachment site for delivery tools such as a pull wire for a pusher or other advancement device. A width or thickness of the coil of the anchor <NUM> can also be varied along the length of the anchor. For example, a central portion of the anchor can be made thinner than end portions of the anchor. This can allow the central portion to exhibit greater flexibility, while the end portions can be stronger or more robust. In certain examples, making the end portions of the coil relatively thicker can also provide more surface area for suturing or otherwise attaching a cover layer to the coil of the anchor.

The helical anchor <NUM> can be configured for insertion through the native valve annulus in a counter-clockwise direction. For example, the anchor can be advanced through commissure A3P3, commissure A1P1, or through another part of the native mitral valve. The counter-clockwise direction of the coil of the anchor <NUM> can also allow for bending of the distal end of the delivery catheter in a similar counter-clockwise direction, which can be easier to achieve than to bend the delivery catheter in the clockwise direction. However, it should be understood that the anchor can be configured for either clockwise or counter-clockwise insertion through the valve, as desired.

Returning to the prosthetic valve of <FIG>, the prosthetic valve <NUM> generally includes a metal frame <NUM> that forms a number of edges. In addition, many frames <NUM> are constructed with edged crowns or apices <NUM> and protruding commissure attachment posts <NUM>, as well as threads <NUM> that can be exposed along an outer surface of the frame <NUM>. These features can cause damage to the native mitral tissue, such as tissue lodged between the prosthetic valve <NUM> and the anchor <NUM>, <NUM>, for example, by movement or friction between the native tissue and the various abrasive surfaces of the prosthetic valve <NUM>. In addition, other native tissue in close proximity to the prosthetic valve <NUM>, such as the chordae tendinae, can also potentially be damaged.

<FIG> illustrate a prosthetic heart valve <NUM> similar to the Edwards Lifesciences SAPIEN™ <NUM> valve, which is described in detail in <CIT>. The prosthetic valve <NUM> includes a frame <NUM> formed by a plurality of angled strut members <NUM>, and having an inflow end <NUM> and an outflow end <NUM>. The prosthetic valve <NUM> also includes a leaflet structure comprising three leaflets <NUM> situated at least partially within the frame <NUM> and configured to collapse in a tricuspid arrangement similar to the aortic valve, although the prosthetic valve can also include two leaflets configured to collapse in a bicuspid arrangement in the manner of the mitral valve, or more than three leaflets, as desired. The strut members <NUM> can form a plurality of apices <NUM> arranged around the inflow and outflow ends of the frame.

The prosthetic heart valve can include an outer covering <NUM> configured to cushion (protect) native tissue in contact with the prosthetic valve after implantation, and to reduce damage to the tissue due to movement or friction between the tissue and surfaces of the valve. The covering <NUM> can also reduce paravalvular leakage. In <FIG>, the covering <NUM> includes a first layer configured as a backing layer <NUM> (see, e.g., <FIG>), and a second layer configured as a cushioning layer <NUM>. The cushioning layer <NUM> can be disposed on the backing layer <NUM>, and comprises a soft, plush surface <NUM> oriented radially outward so as to protect tissue or objects in contact with the cushioning layer. The covering <NUM> also includes an atraumatic inflow protective portion <NUM> extending circumferentially around the inflow end <NUM> of the frame, and an atraumatic outflow protective portion <NUM> extending circumferentially around the outflow end <NUM> of the frame. The portion of the cushioning layer <NUM> between the inflow and outflow protective portions <NUM>, <NUM> can define a main cushioning portion <NUM>.

<FIG> is a cross-sectional view schematically illustrating the prosthetic valve <NUM> with the leaflet structure removed for purposes of illustration. The covering <NUM> extends around the exterior of the frame <NUM>, such that an interior surface of the backing layer <NUM> is adjacent or against the exterior surfaces of the strut members <NUM>. As illustrated in <FIG>, though not falling within the scope of the claims, the cushioning layer <NUM> can have a length that is greater than the length of the frame as measured along a longitudinal axis <NUM> of the frame. Thus, the covering <NUM> can be situated such that the cushioning layer <NUM> extends distally (e.g., in the upstream direction) beyond the apices <NUM> of the strut members at the inflow end <NUM> of the frame, with the portion of the cushioning layer extending beyond the apices being referred to herein as distal end portion <NUM>. At the opposite end of the valve, the cushioning layer <NUM> can extend proximally (e.g., in the downstream direction) beyond the apices <NUM> of the strut members, with the portion located beyond the apices being referred to as proximal end portion <NUM>. The distances by which the proximal and distal end portions <NUM>, <NUM> of the cushioning layer <NUM> extend beyond the apices at the respective end of the valve can be the same or different depending upon, for example, the dimensions of the valve, the particular application, etc..

The backing layer <NUM> can have sufficient length in the axial direction such that a proximal end portion or flap <NUM> of the backing layer <NUM> can be folded over the proximal end portion <NUM> of the cushioning layer <NUM> in the manner of a cuff to form the outflow protective portion <NUM>. Meanwhile, a distal end portion or flap <NUM> of the backing layer <NUM> can be folded over the distal end portion <NUM> of the cushioning layer <NUM> to form the inflow protective portion <NUM>. The proximal and distal flaps <NUM>, <NUM> of the backing layer <NUM> can be secured to the underlying section of the backing layer by, for example, sutures <NUM>. In this manner, the inflow and outflow protective portions <NUM>, <NUM> are constructed such that the proximal and distal end portions <NUM>, <NUM> of the cushioning layer <NUM> are at least partially enclosed by the flaps <NUM>, <NUM> of the backing layer <NUM>. This construction provides sufficient strength and resistance to bending to the inflow and outflow protective portions <NUM>, <NUM> so that they extend along the longitudinal axis <NUM> of the valve without bending or otherwise protruding into the inner diameter of the valve (e.g., by bending under their own weight, by blood flow, or by blood pressure). In this manner, the inflow and outflow protective portions <NUM>, <NUM> minimally impact flow through the prosthetic valve and avoid interfering with the prosthetic valve leaflets, reducing flow disturbances and the risk of thrombus.

In the illustrated configuration, the inflow protective portion <NUM> can extend beyond the apices <NUM> of the strut members at the inflow end of the frame by a distance d<NUM>, and the outflow protective portion <NUM> can extend beyond the apices <NUM> of the strut members at the outflow end of the frame by a distance d<NUM>. The distances d<NUM> and d<NUM> can be the same or different, depending upon the type of prosthetic valve, the treatment location, etc. For example, for a <NUM> prosthetic valve, the distances d<NUM> and d<NUM> can be from about <NUM> to about <NUM>. The distances d<NUM> and d<NUM> can be from about <NUM> to about <NUM>. Because the inflow and outflow protective portions <NUM>, <NUM> extend beyond the apices <NUM> of the respective ends of the frame, the inflow and outflow protective portions can shield adjacent tissue and/or another implant adjacent the prosthetic valve from contacting the apices <NUM> of the frame.

For example, <FIG> illustrates the prosthetic valve <NUM> implanted within a helical anchor <NUM> in the native mitral valve <NUM>, similar to <FIG> and <FIG> above. In the illustrated example, the inflow end portion of the prosthetic valve is positioned above the superior surface of the native mitral valve annulus and spaced from surrounding tissue. However, in other implementations, depending on the axial positioning of the prosthetic valve, the inflow protective portion <NUM> can contact the native leaflets <NUM> and prevent them from directly contacting the apices <NUM> at the inflow end of the frame. Depending on the diameter of the prosthetic valve at the inflow end, the inflow protective portion <NUM> can serve to prevent the atrium wall from directly contacting the apices <NUM> at the inflow end of the frame.

As shown in <FIG>, the anchor <NUM> can also rest against the compliant inflow protective portion <NUM>. Meanwhile, the portions of the native leaflets <NUM> captured between the anchor <NUM> and the prosthetic valve <NUM> is cushioned by the plush surface <NUM> of the main cushioning portion <NUM>. The soft, compliant nature and texture of the cushioning layer <NUM> can increase friction between the native leaflets and the prosthetic valve. This can reduce relative movement of the native leaflets and the prosthetic valve as the left ventricle expands and contracts, reducing the likelihood of damage to the native leaflets and the surrounding tissue. The cushioning layer <NUM> can also provide increased retention forces between the anchor <NUM> and the prosthetic valve <NUM>. The plush, compressible nature of the cushioning layer <NUM> can also reduce penetration of the covering <NUM> through the openings in the frame <NUM> caused by application of pressure to the covering, thereby reducing interference with the hemodynamics of the valve. Additionally, the outflow cushioning portion <NUM> can protect the chordae tendineae <NUM> from contacting the strut members of the frame, and in particular the apices <NUM> at the outflow end of the frame, thereby reducing the risk of injury or rupture of the chordae.

The backing layer <NUM> can comprise, for example, any of various woven fabrics, such as gauze, polyethylene terephthalate (PET) fabric (e.g., Dacron), polyester fabric, polyamide fabric, or any of various non-woven fabrics, such as felt. The backing layer <NUM> can also comprise a film including any of a variety of crystalline or semi-crystalline polymeric materials, such as polytetrafluorethylene (PTFE), PET, polypropylene, polyamide, polyetheretherketone (PEEK), etc. In this manner, the backing layer <NUM> can be relatively thin and yet strong enough to allow the covering <NUM> to be sutured to the frame, and to allow the prosthetic valve to be crimped, without tearing.

As stated above, the cushioning layer <NUM> comprises at least one soft, plush surface <NUM>. The cushioning layer <NUM> can be made from any of a variety of woven or knitted fabrics wherein the surface <NUM> is the surface of a plush nap or pile of the fabric. Exemplary fabrics having a pile include velour, velvet, velveteen, corduroy, terrycloth, fleece, etc. <FIG> illustrates an example of the cushioning layer <NUM> in greater detail. In <FIG>, the cushioning layer <NUM> can have a base layer <NUM> (a first layer) from which the pile <NUM> (a second layer) extends. The base layer <NUM> can comprise warp and weft yarns woven or knitted into a mesh-like structure. For example, in a representative configuration, the yarns of the base layer <NUM> can be flat yarns with a denier range of from about <NUM> dtex to about <NUM> dtex, and can be knitted with a density of from about <NUM> to about <NUM> wales per inch and from about <NUM> to about <NUM> courses per inch. The yarns can be made from, for example, biocompatible thermoplastic polymers such as PET, Nylon, ePTFE, etc., other suitable natural or synthetic fibers, or soft monolithic materials.

The pile <NUM> can comprise pile yarns <NUM> woven or knitted into loops. In certain configurations, the pile yarns <NUM> can be the warp yarns or the weft yarns of the base layer <NUM> woven or knitted to form the loops. The pile yarns <NUM> can also be separate yarns incorporated into the base layer, depending upon the particular characteristics desired. The loops can be cut such that the pile <NUM> is a cut pile in the manner of, for example, a velour fabric. <FIG> illustrate an example of the cushioning layer <NUM> configured as a velour fabric. Alternatively, the loops can be left intact to form a looped pile in the manner of, for example, terrycloth. <FIG> illustrates an example of the cushioning layer <NUM> in which the pile yarns <NUM> are knitted to form loops <NUM>. <FIG> illustrates an example of the covering <NUM> incorporating the cushioning layer <NUM> of <FIG>.

In some configurations, the pile yarns <NUM> can be textured yarns having an increased surface area due to, for example, a wavy or undulating structure. In configurations such as the looped pile cushioning layer of <FIG>, the loop structure and the increased surface area provided by the textured yarn of the loops <NUM> can allow the loops to act as a scaffold for tissue growth into and around the loops of the pile. Promoting tissue growth into the pile <NUM> can increase retention of the valve at the implant site and contribute to long-term stability of the valve.

The cushioning layers described herein can also contribute to improved compressibility and shape memory properties of the covering <NUM> over known valve coverings and skirts. For example, the pile <NUM> can be compliant such that it compresses under load (e.g., when in contact with tissue, implants, or the like), and returns to its original size and shape when the load is relieved. This can help to improve sealing between the cushioning layer <NUM> and, for example, support structures or other devices such as the helical anchor <NUM> in which the prosthetic valve is deployed, or between the cushioning layer and the walls of the native annulus. The compressibility provided by the pile <NUM> of the cushioning layer <NUM> is also beneficial in reducing the crimp profile of the prosthetic valve. Additionally, the covering <NUM> can prevent the leaflets <NUM> or portions thereof from extending through spaces between the strut members <NUM> as the prosthetic valve is crimped, thereby reducing damage to the prosthetic leaflets due to pinching of the leaflets between struts.

Alternatively, the cushioning layer <NUM> be made of non-woven fabric such as felt, or fibers such as non-woven cotton fibers. The cushioning layer <NUM> can also be made of porous or spongey materials such as, for example, any of a variety of compliant polymeric foam materials, or woven or knitted fabrics, such as woven or knitted PET. Still alternatively, the proximal and distal end portions of the cushioning layer <NUM> of <FIG> can be free of loops <NUM>, and the inflow and outflow protective portions <NUM>, <NUM> can be formed by folding the base layer <NUM> back on itself to form cuffs at the inflow and outflow ends of the valve.

In <FIG>, the covering <NUM> of <FIG> can be made by cutting a fabric material (e.g., a PET fabric) with a stencil <NUM> to form the backing layer <NUM>. The stencil <NUM> is shaped like a parallelogram, although other configurations are possible. The angles of the corners of the stencil <NUM> can be shaped such that the fabric material is cut at about a <NUM> degree angle relative to the direction of the fibers of the fabric. This can improve the crimpability of the resulting backing layer <NUM> by, for example, allowing the backing layer to stretch along a direction diagonal to the warp and weft yarns. <FIG> illustrates a plan view of a representative example of the backing layer <NUM> after being cut using the parallelogram stencil <NUM>.

The cushioning layer <NUM> can be attached (e.g., by sutures, adhesive, etc.) to the backing layer <NUM>. In <FIG>, the location of the proximal and distal ends of the frame <NUM> when the covering is attached to the frame are represented as dashed lines <NUM>, <NUM> on the backing layer <NUM>. Meanwhile, dashed lines <NUM>, <NUM> represent the location of the proximal and distal edges of the cushioning layer <NUM> once the cushioning layer is secured to the backing layer. For example, the cushioning layer <NUM> can be sutured to the backing layer <NUM> along the proximal and distal edges at or near lines <NUM>, <NUM>. As shown in <FIG>, line <NUM> representing the proximal edge of the cushioning layer <NUM> can be offset from the proximal edge <NUM> of the backing layer <NUM> by a distance d<NUM> to create the proximal flap <NUM>. Meanwhile, line <NUM> representing the distal edge of the cushioning layer <NUM> can be offset from the distal edge <NUM> of the backing layer <NUM> by a distance d<NUM> to create the distal flap <NUM>. The distances d<NUM> and d<NUM> can be the same or different, as desired. For example, depending upon the size of the valve and the size of the inflow and outflow cushioning portions, the distances d<NUM> and d<NUM> can be, for example, about <NUM>-<NUM>. The distances d<NUM> and d<NUM> can be about <NUM>.

Once the cushioning layer <NUM> is secured to the backing layer <NUM>, the resulting swatch can be folded and sutured into a cylindrical shape. The flaps <NUM>, <NUM> of the backing layer <NUM> can be folded over the edges of the cushioning layer <NUM> and sutured to form the inflow and outflow protective portions <NUM>, <NUM>. The resulting covering <NUM> can then be secured to the frame <NUM> by, for example, suturing it the strut members <NUM>.

<FIG> illustrate an example of the covering <NUM> in which the inflow and outflow protective portions <NUM>, <NUM> are formed with separate pieces of material that wrap around the ends of the cushioning layer <NUM> at the inflow and outflow ends of the valve. For example, the proximal end portion <NUM> of the cushioning layer <NUM> can be covered by a member configured as a strip <NUM> of material that wraps around the cushioning layer from the interior surface <NUM> (e.g., the surface adjacent the frame) of the cushioning layer <NUM>, over the circumferential edge of the proximal end portion <NUM>, and onto the exterior surface <NUM> of the cushioning layer to form the outflow protective portion <NUM>. Likewise, a material strip member <NUM> can extend from the interior surface <NUM> of the cushioning layer, over the circumferential edge of the distal end portion <NUM>, and onto the exterior surface of the cushioning layer to form the inflow protective portion <NUM>. The strip members <NUM>, <NUM> can be sutured to the cushioning layer <NUM> along the proximal and distal edge portions <NUM>, <NUM> of the cushioning layer at suture lines <NUM>, <NUM>, respectively.

In certain configurations, the strip members <NUM>, <NUM> can be made from any of various natural materials and/or tissues, such as pericardial tissue (e.g., bovine pericardial tissue). The strip members <NUM>, <NUM> can also be made of any of various synthetic materials, such as PET and/or expanded polytetrafluoroethylene (ePTFE). In some configurations, making the strip members <NUM>, <NUM> from natural tissues such as pericardial tissue can provide desirable properties such as strength, durability, fatigue resistance, and compliance, and cushioning and reduced friction with materials or tissues surrounding the implant.

<FIG> illustrates a prosthetic valve <NUM> including an outer covering <NUM> comprising a cushioning layer <NUM> made of a spacer fabric and thus not falling within the scope of the claims. The outer covering <NUM> is shown without inflow and outflow protective portions, and with the cushioning layer <NUM> extending along the full length of the frame from the inflow end to the outflow end of the valve. However, the outer covering <NUM> may also include inflow and/or outflow protective portions, as described elsewhere herein.

Referring to <FIG> and <FIG>, the spacer fabric cushioning layer can comprise a first layer <NUM>, a second layer <NUM>, and a spacer layer <NUM> extending between the first and second layers to create a three-dimensional fabric. The first and second layers <NUM>, <NUM> can be woven fabric or mesh layers. In certain configurations, one or more of the first and second layers <NUM>, <NUM> can be woven such that they define a plurality of openings <NUM>. In some examples, openings such as the openings <NUM> can promote tissue growth into the covering <NUM>. Alternatively, the layers <NUM>, <NUM> need not define openings, but can be porous, as desired.

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

In certain examples, the pile yarns <NUM> can have a rigidity that is greater than the rigidity of the fabric of the first and second layers <NUM>, <NUM> such that the pile yarns <NUM> can extend between the first and second layers <NUM>, <NUM> without collapsing under the weight of the second layer <NUM>. The pile yarns <NUM> can also be sufficiently resilient such that the pile yarns can bend or give when subjected to a load, allowing the fabric to compress, and return to their non-deflected state when the load is removed.

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

<FIG> illustrate a prosthetic heart valve <NUM> including an outer covering with inflow and outflow protective portions that encapsulate the apices of the strut members. For example, the prosthetic valve can include a frame <NUM> formed by a plurality of strut members <NUM> defining apices <NUM> (<FIG> and <FIG>), and can have an inflow end <NUM> and an outflow end <NUM>. A plurality of leaflets <NUM> can be situated at least partially within the frame <NUM>.

The prosthetic valve can include an outer covering <NUM> situated about the frame <NUM>. The outer covering <NUM> includes a main cushioning layer <NUM> including a plush exterior surface <NUM> (e.g., a first surface), similar to the cushioning layer <NUM> of <FIG> above. The covering <NUM> can also include an inflow protective portion <NUM> extending circumferentially around the inflow end <NUM> of the valve, and an outflow protective portion <NUM> extending circumferentially around the outflow end <NUM> of the valve. The inflow and outflow protective portions <NUM>, <NUM> can be formed with separate pieces of material that are folded around the circumferential ends of the cushioning layer <NUM> at the inflow and outflow ends of the valve such that the protective portions encapsulate the apices <NUM> of the strut members.

For example, with reference to <FIG>, the inflow protective portion <NUM> can comprise a member configured as a strip <NUM> of material including a first circumferential edge portion <NUM> and a second circumferential edge portion <NUM>. The strip member <NUM> of material can be folded such that the first circumferential edge portion <NUM> is adjacent (e.g., contacting) an inner skirt <NUM> disposed within the frame <NUM>. The first circumferential edge portion <NUM> thereby forms a first or inner layer of the inflow protective portion <NUM>. The strip member <NUM> can extend over the apices <NUM> of the strut members, and over an inflow end portion <NUM> of the cushioning layer <NUM> such that the second circumferential edge portion <NUM> is disposed on the exterior surface <NUM> of the cushioning layer <NUM>. In this manner, the inflow end portion <NUM> of the cushioning layer <NUM> can form a second layer of the inflow protective portion <NUM>, and the second circumferential edge portion <NUM> can form a third or outer layer of the inflow protective portion. The first and second circumferential edge portions <NUM>, <NUM> of the strip member <NUM> can be secured to the strut members <NUM> (e.g., the rung of struts nearest the inflow end <NUM>) with sutures <NUM>, <NUM>. Thus, the strip member <NUM> can encapsulate the apices <NUM>, along with the inflow end portion <NUM> of the cushioning layer <NUM>, between the first and second circumferential edge portions <NUM>, <NUM>.

In the illustrated configuration, the inflow protective portion <NUM> can extend beyond the apices <NUM> of the frame, similar to what is described above. In particular, the inflow end portion <NUM> of the cushioning layer <NUM> can extend beyond the apices <NUM> of the frame and into the inflow protective portion <NUM> within the folded strip <NUM>. In this manner, the inflow end portion <NUM> of the cushioning layer <NUM>, together with the strip member <NUM>, can impart a resilient, cushioning quality to the inflow protective portion <NUM>. This can also allow the inflow protective portion <NUM> to resiliently deform to accommodate and protect, for example, native tissue, other implants, etc., that come in contact with the inflow protective portion.

The inflow end portion <NUM> can extend beyond the apices <NUM> by a distance d<NUM>. The distance d<NUM> can be configured such the inflow end portion <NUM> can extend over or cover the apices <NUM> when the inflow protective portion <NUM> comes in contact with, for example, native tissue at the treatment site. The strip member <NUM> can also form a dome over the edge of the of the inflow end portion <NUM> such that the edge of the inflow end portion <NUM> is spaced apart from the domed portion of the strip member <NUM>. Alternatively, the strip member <NUM> can be folded such that it contacts the edge of the inflow edge portion <NUM>, similar to <FIG>.

The outflow protective portion <NUM> includes a member configured as a strip <NUM> of material folded such that a first circumferential edge portion <NUM> is adjacent (e.g., contacting) inner surfaces <NUM> of the strut members, and a second circumferential edge portion <NUM> is disposed on the exterior surface <NUM> of the cushioning layer <NUM>, similar to the inflow protective portion <NUM>. An outflow end portion <NUM> of the cushioning layer <NUM> can extend beyond the apices <NUM> by a distance d<NUM>, and can be encapsulated by the strip member <NUM> together with the apices <NUM> between the first and second circumferential edge portions <NUM>, <NUM>. The distance d<NUM> can be the same as distance d<NUM> or different, as desired. The strip member <NUM> can be secured to the strut members <NUM> with sutures <NUM>, <NUM>. The strip member <NUM> can also form a domed shape similar to the strip member <NUM>.

The cushioning layer <NUM> is a fabric including a plush pile, such as a velour fabric, or any other type of plush knitted, woven, or non-woven material, as described above. In certain configurations, the strip members <NUM>, <NUM> can be made of resilient natural tissue materials such as pericardium. Alternatively, the strip members can also be made from fabric or polymeric materials such as PTFE or ePTFE.

<FIG> illustrate a representative method of making the outer covering <NUM> and attaching the covering to the prosthetic valve <NUM> to form the inflow and outflow protective portions <NUM>, <NUM>. <FIG> illustrates the outer covering <NUM> in an unfolded configuration prior to securing the covering to the frame <NUM>. As illustrated in <FIG>, the second circumferential edge portion <NUM> of the strip member <NUM> can be sutured to the plush surface <NUM> (e.g., the first surface) of the cushioning layer <NUM> at the inflow end portion <NUM> of the cushioning layer. The second circumferential edge portion <NUM> of the strip member <NUM> can be sutured to the plush surface <NUM> of the cushioning layer <NUM> at the outflow end portion <NUM> of the cushioning layer.

In the illustrated configuration, the cushioning layer <NUM> and the strip members <NUM>, <NUM> can have a length dimension L corresponding to a circumference of the frame <NUM>. In a representative example, the length dimension L can be about <NUM>. The strip members <NUM>, <NUM> can also have respective width dimensions W<NUM>, W<NUM>. Referring to width dimension W<NUM> for purposes of illustration, the width dimension W<NUM> can be configured such that the strip member <NUM> extends from the interior of the valve to the exterior of the valve without contacting the apices <NUM> of the strut members, as shown in <FIG>. For example, the width dimension W<NUM> can be configured such that the strip member <NUM> extends from adjacent the rung of strut members <NUM> at the inflow end <NUM> of the frame to the exterior of the valve adjacent the same rung of strut members and forms a domed shape over the apices <NUM>. In certain configurations, the width dimension W<NUM> can be about <NUM>. The width dimension W<NUM> can be the same as W<NUM> or different, as desired.

Referring to <FIG>, the outer covering <NUM> can be folded and sutured into a cylindrical shape. The outer covering <NUM> can then be situated around the frame <NUM> such that a second or interior surface <NUM> of the cushioning layer <NUM> is oriented toward the frame. In certain configurations, the frame <NUM> can already include the inner skirt <NUM> and the leaflet structure <NUM>, as shown in <FIG>.

Referring to <FIG>, the outer covering <NUM> can then be sutured to the frame. For example, as illustrated in <FIG>, the strip member <NUM> can be aligned with an adjacent rung of strut members <NUM> (e.g., the rung of strut members nearest the inflow end of the frame). The cushioning layer <NUM> and/or the strip member <NUM> can then be sutured to the strut members <NUM> at suture line <NUM>. The strip member <NUM> can then be folded over the apices <NUM> at the inflow end of the frame, and the first and second circumferential edge portions <NUM>, <NUM> can be sutured to each other at suture line <NUM> to form the inflow protective portion <NUM>. Alternatively, the strip member <NUM> can be folded and sutured to form the inflow protective portion <NUM> before the outer covering <NUM> is sutured to the frame.

The outflow protective portion <NUM> can be formed in a similar manner. For example, the strip member <NUM> can be aligned with the rung of strut members <NUM> adjacent the outflow end <NUM> of the frame, and the strip member <NUM> and/or the cushioning layer <NUM> can be sutured to the strut members. The strip member <NUM> can then be folded over the apices <NUM> and the cushioning layer <NUM> at the outflow end of the frame, and the first and second circumferential edge portions <NUM>, <NUM> can be sutured together, and to the rung of strut members <NUM> adjacent the outflow end of the frame, to form the outflow protective portion <NUM>. The covering <NUM> can also be sutured to the frame at one or more additional locations, such as at suture lines <NUM> and <NUM>, as shown in <FIG>.

<FIG> illustrate another prosthetic heart valve <NUM> including a frame <NUM> formed by a plurality of strut members <NUM> defining apices <NUM> (<FIG>), similar to the frame <NUM> described above and in <CIT>. The prosthetic valve <NUM> can have an inflow end <NUM> and an outflow end <NUM>, and can include a leaflet structure (not shown) situated at least partially within the frame.

The prosthetic valve can include an outer covering <NUM> situated about the frame <NUM>. The outer covering <NUM> can include a main cushioning layer <NUM> (also referred to as a main layer) having a cylindrical shape, and made from a woven, knitted, or braided fabric (e.g., a PET fabric, an ultra-high molecular weight polyethylene (UHMWPE) fabric, a PTFE fabric, etc.). The fabric of the main cushioning layer <NUM> can include a plush pile. The fabric of the main cushioning layer <NUM> can comprise texturized yarns in which the constituent fibers of the yarns have been bulked by, for example, being twisted, heat set, and untwisted such that the fibers retain their deformed, twisted shape and create a voluminous fabric. The volume contributed by the texturized yarns can improve the cushioning properties of the covering, as well as increase friction between the fabric and the surrounding anatomy and/or an anchoring device into which the valve is deployed.

The outer covering <NUM> can include an inflow protective portion <NUM> extending circumferentially around the inflow end <NUM> of the frame, and an outflow protective portion <NUM> extending circumferentially around the outflow end <NUM> of the frame. The inflow and outflow protective portions <NUM> and <NUM> can be formed on the fabric of the main cushioning layer <NUM> such that the outer covering <NUM> is a one-piece, unitary construction, as described further below.

Referring to <FIG>, the main cushioning layer <NUM> can include a first circumferential edge portion <NUM> (also referred to as an inflow edge portion) located adjacent the inflow end <NUM> of the valve, which can form a part of the inflow protective portion <NUM>. The cushioning layer <NUM> can further include a second circumferential edge portion <NUM> (also referred to as an outflow edge portion) located adjacent the outflow end <NUM> of the valve, and which can form a part of the outflow protective portion <NUM>. Referring still to <FIG>, the first circumferential edge portion <NUM> can comprise an edge <NUM>, and the second circumferential edge portion <NUM> can comprise an edge <NUM>. The first circumferential edge portion <NUM> can be folded or wrapped over the apices <NUM> of the strut members <NUM> such that the edge <NUM> is disposed on the inside of the frame <NUM>. The second circumferential edge portion <NUM> can be folded around the apices <NUM> at the outflow end <NUM> of the frame in a similar fashion such that the edge <NUM> is also disposed on the inside of the frame opposite the edge <NUM>.

In the illustrated configuration, the inflow protective portion <NUM> can include a second or outer layer configured as a lubricious layer <NUM> of material disposed on an outer surface <NUM> of the main cushioning layer <NUM>. The outflow protective portion <NUM> can also include a second or outer lubricious layer <NUM> of material disposed on the outer surface <NUM> of the main cushioning layer <NUM>. The layers <NUM> and <NUM> can be smooth, low-thickness coatings comprising a low-friction or lubricious material. For example, in certain configurations one or both of the layers <NUM>, <NUM> can comprise PTFE or ePTFE.

In the illustrated configuration, the lubricious layer <NUM> can have a first circumferential edge <NUM> (<FIG>) and a second circumferential edge <NUM> (<FIG>). The lubricious layer <NUM> can extend from the outer surface <NUM> of the main cushioning layer <NUM> and over the apices <NUM> such that the first circumferential edge <NUM> is disposed on the outside of the frame and the second circumferential edge <NUM> is disposed on the inside of the frame. The lubricious layer <NUM> can be configured similarly, such that a first circumferential edge <NUM> (<FIG>) is disposed outside the frame, the layer <NUM> extends over the apices <NUM> of the outflow end <NUM> of the frame, and a second circumferential edge <NUM> (<FIG>) is disposed inside the frame. Once implanted in a native heart valve, the protection portions <NUM> and <NUM> can prevent direct contact between the apices <NUM> and the surrounding anatomy. The lubricious material of the layers <NUM> and <NUM> can also reduce friction with tissue of the native valve (e.g., chordae) in contact with the inflow and outflow ends of the prosthetic valve, thereby preventing damage to the tissue. Alternatively, the entire outer surface <NUM> of the main cushioning layer <NUM>, or a portion thereof, can be covered with a lubricious coating such as ePTFE in addition to the inflow and outflow protective portions <NUM> and <NUM> such that the lubricious coating extends axially from the inflow end to the outflow end of the covering. Still alternatively, the cushioning layer <NUM> can be formed from woven, knitted, braided, or electrospun fibers of lubricious material, such as PTFE, ePTFE, etc., and can form the inflow and outflow protective portions.

<FIG> illustrate a representative method of making the covering <NUM>. <FIG> illustrates the main cushioning layer <NUM> formed into a cylindrical, tubular body. Referring to <FIG>, the first circumferential edge portion <NUM> of the cushioning layer <NUM> can then be folded over (e. g, inward toward the interior surface of the tubular body) in the direction of arrows <NUM> such that the lower edge <NUM> is inside the tubular body and disposed against the interior surface of the tubular body. The edge portion <NUM> can be folded in a similar manner as indicated by arrows <NUM> such that the top edge <NUM> is inside the tubular body and disposed against the interior surface.

Referring to <FIG>, the lubricious layers <NUM>, <NUM> can then be applied to the main layer <NUM> to form the inflow and outflow protection portions <NUM> and <NUM>. The lubricious layers <NUM>, <NUM> can be formed by electrospinning a low-friction material (e.g., PTFE, ePTFE, etc.) onto the first and second circumferential edge portions <NUM> and <NUM>. Forming the layers <NUM>, and <NUM> by electrospinning can provide a smooth, uniform surface, and keep the thickness of the layers within strictly prescribed specifications.

For example, the layers <NUM> and <NUM> can be made relatively thin, which can reduce the overall crimp profile of the valve. A thickness of the layers <NUM> and <NUM> can be from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM>, or about <NUM>. Alternatively, the layer <NUM> and/or <NUM> can be made by dip-coating, spray-coating, or any other suitable method for applying a thin layer of lubricious material to the main cushioning layer <NUM>. The finished outer covering <NUM> can then be situated about and secured to the frame <NUM> using, for example, sutures, ultrasonic welding, or any other suitable attachment method. Alternatively, the main cushioning layer <NUM> can be situated about the frame <NUM> before the edges are folded, and/or before the lubricious layers <NUM> and <NUM> are applied.

In addition to covering the frame <NUM> and the apices <NUM>, the outer covering <NUM> can provide a number of other significant advantages. For example, the covering <NUM> can be relatively thin, allowing the prosthetic valve to achieve a low crimp profile (e.g., <NUM> Fr or below). The one-piece, unitary construction of the outer covering <NUM> and the protective portions <NUM> and <NUM> can also significantly reduce the time required to produce the covering and secure it to the frame, and can increase production yield.

One or both of the inflow and outflow protection portions can be configured as separate coverings that are spaced apart from the main outer covering, and may or may not be coupled to the main outer covering. For example, <FIG> illustrate another prosthetic heart valve <NUM> including a frame <NUM> formed by a plurality of strut members <NUM> defining apices <NUM>, similar to the frame <NUM> described above and in <CIT>. The prosthetic valve <NUM> can have an inflow end <NUM> and an outflow end <NUM>, and can include a plurality of leaflets <NUM> situated at least partially within the frame.

<FIG> illustrates a portion of the frame <NUM> in a laid-flat configuration for purposes of illustration. The strut members <NUM> can be arranged end-to-end to form a plurality of rows or rungs of strut members that extend circumferentially around the frame <NUM>. For example, with reference to <FIG>, the frame <NUM> can comprise a first or lower row I of angled strut members forming the inflow end <NUM> of the frame; a second row II of strut members above the first row; a third row III of strut members above the second row; a fourth row IV of strut members above the third row, and a fifth row V of strut members above the fourth row and forming the outflow end <NUM> of the frame. At the outflow end <NUM> of the frame, the strut members <NUM> of the fifth row V can be arranged at alternating angles in a zig-zag pattern. The strut members <NUM> of the fifth row V can be j oined together at their distal ends (relative to the direction of implantation in the mitral valve) to form the apices <NUM>, and joined together at their proximal ends at junctions <NUM>, which may form part of the commissure windows <NUM>. Additional structure and characteristics of the rows I-V of strut members <NUM> are described in greater detail in <CIT>.

Returning to <FIG> and <FIG>, the prosthetic valve can include a first covering <NUM> (also referred to as a main covering) situated about the frame <NUM>. The valve can also include an outflow protective portion configured as a second covering <NUM> disposed about the strut members <NUM> and the apices <NUM> of the fifth row V of strut members at the outflow end <NUM> of the frame. The first covering <NUM> can comprise a woven or knitted fabric made from, for example, PET, UHMWPE, PTFE, etc. Referring to <FIG>, the first covering <NUM> can include an inflow end portion <NUM> located at the inflow end <NUM> of the valve, and an outflow end portion <NUM> located at the outflow end <NUM> of the valve. The outflow end portion <NUM> of the first covering <NUM> can be offset toward the inflow end of the frame (e.g., in the upstream direction) from the fifth row V of strut members <NUM>. Stated differently, the strut members <NUM> of the fifth row V can extend beyond an uppermost circumferential edge <NUM> of the first covering <NUM> (e.g., distally beyond the edge <NUM> when the prosthetic valve is implanted in the mitral valve). A lowermost circumferential edge <NUM> of the main covering <NUM> can be disposed adjacent the first row I of strut members <NUM> at the inflow end <NUM> of the valve. The first covering <NUM> can extend over and cover the apices <NUM> at the inflow end <NUM> of the frame.

<FIG> illustrates the frame <NUM> including the second covering <NUM> and an inner skirt <NUM>, and without the first covering <NUM> for purposes of illustration. The second covering <NUM> can be configured as a wrapping that extends around the circumference of the frame <NUM> and surrounds the fifth row V of strut members <NUM>. For example, with reference to <FIG>, the covering <NUM> can be configured as one or more straps or strips <NUM> of material that are helically wrapped around the struts <NUM> and the apices <NUM> of the fifth row V of strut members at the outflow end <NUM> of the frame in the direction such as indicated by arrow <NUM>. In certain configurations, second covering <NUM> can be made of a lubricious or low-friction polymeric material, such as PTFE, ePTFE, UHMWPE, polyurethane, etc. In this manner, the second covering <NUM> can reduce friction between the second covering and native tissue that is in contact with the outflow end <NUM> of the valve. The covering <NUM> can also prevent injury to native tissue by preventing it from directly contacting the apices <NUM>.

The strip <NUM> can be relatively thick to improve the cushioning characteristics of the second covering <NUM>. For example, the strip <NUM> can be a PTFE strip having a thickness of from about <NUM> to about <NUM>, and a width of from about <NUM> to about <NUM>. The strip <NUM> can have a thickness of about <NUM>, and a width of about <NUM>. The second covering <NUM> can also include one or multiple layers. For example, the second covering <NUM> can include a single layer (e.g., a single strip <NUM>) wrapped around a row of struts of the frame. The second covering may also include two layers, three layers, or more of strips wrapped around a row of struts of the frame. The second covering <NUM> can comprise multiple layers made of different materials. In certain configurations, the second covering <NUM> can also be porous, and can have a pore size and pore density configured to promote tissue ingrowth into the material of the second covering.

The first covering <NUM> and/or the second covering <NUM> can be secured to the frame by, for example, suturing. The first and second coverings <NUM>, <NUM> can also be secured to each other. For example, with reference to <FIG> and <FIG>, the first covering <NUM> can include one or more sutures <NUM> extending circumferentially around the outflow end portion <NUM> of the first covering in, for example, a running stitch. At or near the junctions <NUM> (<FIG>) of the fifth row V of strut members <NUM>, the suture <NUM> can extend out of the stitch line (e.g., from the radially outward surface of the covering <NUM>), and loop over the second covering <NUM>. The suture <NUM> can then reenter the covering <NUM> (e.g., on the radially inward surface of the covering <NUM>) and resume the running stitch. The suture <NUM> can loop over the second covering <NUM> at the junctions <NUM>. The loops of suture <NUM> thereby rest in "valleys" between the apices <NUM>, and can serve to hold the second covering <NUM> in place on the strut members <NUM>. The suture <NUM> can also hold the first covering <NUM> in place while the valve is being crimped.

Still referring to <FIG> and <FIG>, the circumferential edge <NUM> of the first covering <NUM> can be relatively straight, while the second covering <NUM> can conform to the angled or zig-zag pattern of the fifth row V of strut members <NUM>. In this manner, the first and second coverings <NUM> and <NUM> can define a plurality of gaps or openings <NUM> through the frame <NUM> between the first and second coverings. The openings <NUM> have a triangular shape, with the base of the triangle being defined by the edge <NUM> of the first covering <NUM>, and the sides being defined by the second covering <NUM>. The openings <NUM> can be configured such that after the valve <NUM> is implanted, blood can flow in and/or out of the frame <NUM> through the openings. In this manner, the space between the interior of the frame <NUM> and the ventricular surfaces <NUM> of the leaflets <NUM> can be flushed or washed by blood flowing into and out of the openings <NUM> during operation of the prosthetic valve. This can reduce the risk of thrombus formation and left ventricular outflow tract obstruction.

<FIG> illustrates the frame <NUM> including the second covering <NUM> in a radially collapsed or crimped delivery configuration on a shaft <NUM> of a delivery apparatus. As shown in <FIG>, the second covering <NUM> can conform to the closely-packed, serpentine shape of the strut members <NUM> as they move to the radially collapsed configuration. In certain configurations, the second covering <NUM> can closely mimic the shape and direction of the strut members <NUM> without bulging, pleating, creasing, or bunching to maintain a low crimp profile. Alternatively, the inflow end of the frame can also include a separate covering similar to the covering <NUM>.

<FIG>, <FIG> illustrate the prosthetic valve <NUM> of <FIG> including an outer covering <NUM>. The outer covering <NUM> can include a main cushioning layer <NUM> having a plush exterior surface <NUM>. The covering <NUM> can also include an inflow protection portion <NUM> extending circumferentially around the inflow end <NUM> of the valve, and an outflow protection portion <NUM> extending circumferentially around the outflow end <NUM> of the valve. As in <FIG>, the inflow and outflow protection portions <NUM>, <NUM> can be formed with separate pieces of material that are folded around the circumferential ends of the main layer <NUM> such that the cushioning portions encapsulate the apices <NUM> of the strut members at the inflow and outflow ends of the valve. For example, the inflow and outflow protection portions <NUM>, <NUM> can be constructed from strips of material (e.g., polymeric materials such as PTFE, ePTFE, etc., or natural tissues such as pericardium, etc.) folded such that one circumferential edge of the strips is disposed against the interior of the frame <NUM> (or an inner skirt within the frame), and the other circumferential edge is disposed against the outer surface of the main layer <NUM>. The outer covering <NUM> can be secured to the frame <NUM> using, for example, sutures, ultrasonic welding, or any other suitable attachment method.

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

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

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

<FIG> illustrate a cross-sectional view of the main layer <NUM> in which the weft yarns <NUM> extend into the plane of the page. With reference to <FIG>, the fabric of the main layer <NUM> can have a thickness t<NUM> of from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> when in a relaxed state and secured to a frame. The main layer <NUM> can have a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> as measured in a relaxed state with a weighted drop gauge having a presser foot. In a representative example, the main layer <NUM> can have a thickness of about <NUM> when secured to a prosthetic valve frame in the relaxed state. This can allow the fabric of the main layer <NUM> to cushion the leaflets between the valve body and an anchor or ring into which the valve is implanted, as well as to occupy voids or space in the anatomy. The texturized, loosely packed filaments <NUM> of the weft yarns <NUM> in the relaxed state can also promote tissue growth into the main layer <NUM>.

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

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

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

The distance y<NUM> can be, for example, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. In a representative example, the distance y<NUM> can be about <NUM>. When the fabric is stretched as in <FIG> and <FIG>, the distance y<NUM> can be about <NUM> to about <NUM>. Thus, the length of the outer covering <NUM> can vary by <NUM>% or more between the relaxed length L<NUM> and the fully stretched length (e.g., L<NUM>). The fabric's ability to lengthen in this manner can allow the prosthetic valve to be crimped to diameters of, for example, <NUM> Fr, without being limited by the outer covering's ability to stretch. Thus, the outer covering <NUM> can be soft and voluminous when the prosthetic valve is expanded to its functional size, and relatively thin when the prosthetic valve is crimped to minimize the overall crimp profile of the prosthetic valve.

<FIG> show an outer sealing member or covering <NUM> for a prosthetic heart valve (e.g., such as the prosthetic heart valve <NUM>). The sealing member <NUM> can be a dual-layer fabric comprising a base layer <NUM> and a pile layer <NUM>. <FIG> shows the outer surface of the sealing member <NUM> defined by the pile layer <NUM>. <FIG> shows the inner surface of the sealing member <NUM> defined by the base layer <NUM>. The base layer <NUM> in the illustrated configuration comprises a mesh weave having circumferentially extending rows or stripes <NUM> of higher-density mesh portions interspersed with rows or stripes <NUM> of lower-density mesh portions.

The yarn count of yarns extending in the circumferential direction (side-to-side or horizontally in <FIG>) can be greater in the higher-density rows <NUM> than in the lower-density rows <NUM>. Alternatively, the yarn count of yarns extending in the circumferential direction and the yarn count of yarns extending in the axial direction (vertically in <FIG>) can be greater in the higher-density rows <NUM> than in the lower-density rows <NUM>.

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

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

Alternatively, the density of the sealing member <NUM> can vary along the circumference of the sealing member. For example, the pile layer <NUM> can comprise a plurality of axially-extending, circumferentially-spaced, rows of pile yarns, or alternatively, alternating axially-extending rows of higher-density pile interspersed with axially-extending rows of lower-density pile. Similarly, the base layer <NUM> can comprise a plurality axially-extending rows of higher-density mesh interspersed with rows of lower-density mesh.

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

Varying the density of the pile layer <NUM> and/or the base layer <NUM> along the height and/or the circumference of the sealing member <NUM> is advantageous in that it reduces the bulkiness of the sealing member in the radially collapsed state and therefore reduces the overall crimp profile of the prosthetic heart valve.

The outer covering <NUM> can include inflow and/or outflow protective portions similar to the protective portions <NUM> and <NUM> above. However, the outer covering <NUM> need not include protective portions and can extend between the top and bottom row of strut members of a frame, or between intermediate rows of strut members, depending upon the particular application.

Although the prosthetic valve coverings described herein are presented in the context of mitral valve repair, it should be understood that the disclosed coverings can be used in combination with any of various prosthetic heart valves for implantation at any of the valves in the heart. For example, the prosthetic valve coverings described herein can be used in combination with transcatheter heart valves, surgical heart valves, minimally-invasive heart valves, etc. The coverings can be used in valves intended for implantation at any of the native annuluses of the heart (e.g., the aortic, pulmonary, mitral, and tricuspid annuluses), and include valves that are intended for implantation within existing prosthetics valves (so called "valve-in-valve" procedures). The coverings can also be used in combination with other types of devices implantable within other body lumens outside of the heart, or heart valves that are implantable within the heart at locations other than the native valves, such as trans-atrial or trans-ventricle septum valves.

For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved.

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

In the context of the present application, the terms "lower" and "upper" are used interchangeably with the terms "inflow" and "outflow", respectively. Thus, for example, the lower end of the valve is its inflow end and the upper end of the valve is its outflow end.

Claim 1:
A prosthetic heart valve (<NUM>), comprising:
a frame (<NUM>) comprising a plurality of strut members (<NUM>), and having an inflow end (<NUM>) and an outflow end (<NUM>);
a leaflet structure situated at least partially within the frame (<NUM>); and
a covering (<NUM>) disposed around the frame (<NUM>), the covering (<NUM>) comprising a cushioning layer (<NUM>), the cushioning layer (<NUM>) having a plush surface,
characterised in that the covering further comprises an inflow strip member (<NUM>) and an outflow strip member (<NUM>), the inflow strip member (<NUM>) being folded over an inflow end portion (<NUM>) of the cushioning layer (<NUM>) at the inflow end (<NUM>) of the frame (<NUM>) to form an inflow protective portion (<NUM>) that is located adjacent the inflow end (<NUM>) of the frame (<NUM>), and the outflow strip member (<NUM>) being folded over an outflow end portion (<NUM>) of the cushioning layer (<NUM>) at the outflow end (<NUM>) of the frame (<NUM>) to form an outflow protective portion (<NUM>) that is located adjacent the outflow end (<NUM>) of the frame (<NUM>), the inflow and outflow protective portions (<NUM>, <NUM>) extending beyond the strut members (<NUM>) in a direction along a longitudinal axis of the prosthetic heart valve (<NUM>).