Patent Description:
The present disclosure relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present disclosure relates to collapsible prosthetic transcatheter heart valves that minimize or reduce paravalvular leaks.

Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two common types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To load such valves into a delivery apparatus and deliver them into a patient, the valve is first collapsed or crimped to reduce its circumferential size. An example of such valves is disclosed in <CIT>.

When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as a sheath covering the valve is withdrawn.

After implantation, imperfect sealing between the prosthetic valve and the native tissue at the site of implantation may cause complications such as paravalvular leakage ("PV leak") in which retrograde blood flows through one or more gaps formed between the structure of the implanted valve and cardiac tissue as a result of the imperfect sealing.

According to one aspect of the disclosure, a prosthetic heart valve for replacing a native valve includes a stent extending in a longitudinal direction from an inflow end to an outflow end. A valve assembly may be disposed within the stent. A first cuff may be annularly disposed adjacent the stent. A second cuff may have a proximal edge facing toward the inflow end of the stent and a distal edge facing toward the outflow end of the stent. The second cuff may be annularly disposed about the stent radially outward of the first cuff. The distal edge of the second cuff may be coupled to at least one of the first cuff and the stent at a plurality of locations spaced apart in a circumferential direction of the stent to form at least one pocket between the first cuff and the second cuff. The proximal edge of the second cuff may be coupled to at least one of the first cuff and the stent at a spaced distance from the inflow end of the stent.

According to another aspect of the disclosure, a method of implanting a prosthetic heart valve into a valve annulus of a patient may include introducing the prosthetic heart valve into the valve annulus of the patient. The prosthetic heart valve may include a stent, a valve assembly disposed within the stent, a first cuff annularly disposed adjacent the stent, and a second cuff annularly disposed on an exterior of the stent radially outward of the first cuff. The method may include positioning the prosthetic heart valve in the valve annulus of the patient so that a sub-annular portion of the stent extends beyond the native valve annulus so that the sub-annular portion of the stent is not in direct contact with the native valve annulus. The sub-annular portion of the stent includes an inflow end of the stent. A portion of the second cuff may be in direct contact with the native valve annulus. The sub-annular portion of the stent is uncovered by the second cuff.

Various embodiments of the presently disclosed prosthetic heart valve may be more fully understood with reference to the following detailed description when read with the accompanying drawings, in which:.

As used herein in connection with a prosthetic heart valve, the term "inflow end" refers to the end of the heart valve through which blood enters when the valve is functioning as intended, and the term "outflow end" refers to the end of the heart valve through which blood exits when the valve is functioning as intended. As used herein, the term "proximal" refers to the inflow end of a prosthetic heart valve or to elements of a prosthetic heart valve that are relatively close to the inflow end, and the term "distal" refers to the outflow end of a prosthetic heart valve or to elements of a prosthetic heart valve that are relatively close to the outflow end. As used herein, the terms "generally," "substantially," and "about" are intended to mean that slight deviations from absolute are included within the scope of the term so modified. Like numbers refer to similar or identical elements throughout. When used herein in the context of a prosthetic heart valve, or a component thereof, the lengthwise or axial direction refers to a direction parallel to a longitudinal axis passing through the center of the stent or heart valve from the inflow end to the outflow end. When used herein in the context of a prosthetic heart valve, or a component thereof, the circumferential direction refers to a direction extending along the circumference of the prosthetic heart valve.

<FIG> shows a collapsible stent-supported prosthetic heart valve <NUM> according to the prior art, the prosthetic heart valve being shown in an expanded condition. Prosthetic heart valve <NUM> is designed to replace the function of the native aortic valve of a patient. Prosthetic heart valve <NUM> includes a stent <NUM> which serves as a frame for the valve elements. Stent <NUM> extends along a lengthwise or longitudinal axis L from an inflow or annulus end <NUM> to an outflow or aortic end <NUM>, and includes an annulus section <NUM> adjacent inflow end <NUM> and an aortic section <NUM> adjacent outflow end <NUM>. Annulus section <NUM> may be in the form of a cylinder having a substantially constant diameter along its length, and may have a relatively small transverse cross-section in the expanded condition in comparison to the transverse cross-section of aortic section <NUM>. A transition section <NUM> may taper outwardly from annulus section <NUM> to aortic section <NUM>. Each of the sections of stent <NUM> includes a plurality of cells <NUM> formed by interconnected struts <NUM>. Each cell <NUM> may include four struts <NUM> connected together generally in a diamond shape so as to form a cell that may be readily collapsed and expanded. It will be appreciated that a smaller or larger number of struts may be used to form cells having a different shape. The cells <NUM> in each section of stent <NUM> may be connected to one another in one or more annular rows around the stent. For example, as shown in <FIG>, annulus section <NUM> may have two annular rows of complete cells <NUM>, with the cells in one annular row offset by one-half cell width in the circumferential direction from the cells in the other annular row. Aortic section <NUM> and transition section <NUM> may each have one or more annular rows of complete or partial cells <NUM>. The cells in aortic section <NUM> may be larger than the cells in annulus section <NUM> so as to better enable prosthetic valve <NUM> to be positioned within the aortic annulus without the structure of stent <NUM> interfering with blood flow to the coronary arteries. At least partly due to the shape of cells <NUM>, stent <NUM> elongates in the direction of longitudinal axis L as the cells collapse when the stent transitions from the expanded condition to the collapsed condition, and shortens in the direction of longitudinal axis L as the stent transitions from the collapsed condition to the expanded condition.

Stent <NUM> may include one or more retaining elements <NUM> at outflow end <NUM>, the retaining elements being sized and shaped to cooperate with retaining structures provided on a deployment device (not shown). The engagement of retaining elements <NUM> with the retaining structures on the deployment device may help maintain prosthetic heart valve <NUM> in assembled relationship with the deployment device, minimize longitudinal movement of the prosthetic heart valve relative to the deployment device during unsheathing or resheathing procedures, and help prevent rotation of the prosthetic heart valve relative to the deployment device as the deployment device is advanced to the target location and during deployment. One such deployment device is described in <CIT>.

Stent <NUM> may also include a plurality of commissure attachment features <NUM> for mounting the commissures of the valve assembly to the stent. As can be seen in <FIG>, each commissure attachment feature <NUM> may lie at the intersection of four cells <NUM>, two of the cells being adjacent one another in the same annular row, and the other two cells being in different annular rows and lying in end-to-end relationship. Commissure attachment features <NUM> may be positioned entirely within annulus section <NUM> or at the juncture of annulus section <NUM> and transition section <NUM>, and may include one or more eyelets or apertures which facilitate the suturing of the leaflet commissures to stent <NUM>. Stent <NUM> may be formed as a unitary structure, for example, by laser cutting or etching a tube of a superelastic and/or shape-memory metal alloy, such as a nickel-titanium alloy of the type sold under the designation nitinol. Such a unitary structure may be referred to as a "non-woven" structure in that it is not formed by weaving or winding one or more filaments.

Prosthetic heart valve <NUM> includes a valve assembly <NUM> positioned in the annulus section <NUM> of stent <NUM>. Valve assembly <NUM> includes a plurality of leaflets <NUM> that collectively function as a one way valve by coapting with one another, and a cuff <NUM> positioned on the luminal surface of stent <NUM> surrounding leaflets <NUM>. As prosthetic heart valve <NUM> is intended to replace the aortic valve (which ordinarily is a tri-leaflet valve), it is shown in <FIG> with three leaflets <NUM>. Adjacent leaflets <NUM> join one another at leaflet commissures. Each of the leaflet commissures may be sutured to a respective one of the three commissure attachment features <NUM>. Between the leaflet commissures, each leaflet <NUM> may be sutured to stent <NUM> and/or to cuff <NUM> along a leaflet belly B, indicated with broken lines in <FIG>. Leaflets <NUM> may be joined to stent <NUM> and/or to cuff <NUM> by techniques known in the art other than suturing. Above belly B, leaflets <NUM> are free to move radially inward to coapt with one another along their free edges. When prosthetic heart valve <NUM> is implanted in the native aortic valve annulus, blood flows in an antegrade direction from inflow end <NUM>, past leaflets <NUM>, and toward outflow end <NUM>. This occurs when the pressure in the left ventricle is greater than the pressure in the aorta, forcing leaflets <NUM> to open. When the pressure in the aorta is greater than the pressure in the left ventricle, leaflets <NUM> are forced closed and coapt with one another along their free edges, blocking blood from flowing through prosthetic heart valve <NUM> in a retrograde direction from outflow end <NUM> to inflow end <NUM>. It will be appreciated that prosthetic heart valves according to aspects of the present disclosure may have more or less than the three leaflets <NUM> and commissure attachment features <NUM> shown in <FIG> and described above.

Although cuff <NUM> is shown in <FIG> as being disposed on the luminal or inner surface of annulus section <NUM>, the cuff may be disposed on the abluminal or outer surface of the annulus section, or may cover all or part of either or both of the luminal and abluminal surfaces of the annulus section. Cuff <NUM> may be scalloped at the inflow end <NUM> of stent <NUM>, and may have a zig-zag structure at its outflow end, following certain stent struts <NUM> up to commissure attachment features <NUM> and other stent struts closer to the inflow end of the stent at circumferential positions between the commissure attachment features. As is shown in <FIG>, in one example, the entirety of valve assembly <NUM>, including the leaflet commissures, is positioned in the annulus section <NUM> of stent <NUM>. When open, leaflets <NUM> may remain substantially completely within annulus section <NUM>, or they may be designed to extend into transition section <NUM>. In the embodiment shown, substantially the entirety of valve assembly <NUM> is positioned between the inflow end <NUM> of stent <NUM> and commissure attachment features <NUM>, and none of the valve assembly is positioned between the commissure attachment features and the outflow end <NUM> of the stent.

In operation, prosthetic heart valve <NUM> described above may be used to replace a native heart valve, such as the aortic valve; a surgical heart valve; or a heart valve that has undergone a surgical procedure. Prosthetic heart valve <NUM> may be delivered to the desired site (e.g., near the native aortic annulus) using any suitable delivery device. During delivery, prosthetic heart valve <NUM> is disposed inside the delivery device in the collapsed condition. The delivery device may be introduced into the patient using any known percutaneous procedure, such as a transfemoral, transapical, or transseptal delivery procedure. Once the delivery device has reached the target site, the user may deploy prosthetic heart valve <NUM>. Upon deployment, prosthetic heart valve <NUM> expands into secure engagement within the native aortic annulus. When prosthetic heart valve <NUM> is properly positioned inside the heart, it works as a one-way valve, allowing blood to flow in one direction and preventing blood from flowing in the opposite direction.

<FIG> is a highly schematic transverse cross-sectional illustration taken along line <NUM>-<NUM> of <FIG> and showing prosthetic heart valve <NUM> with leaflets <NUM> disposed within native valve annulus <NUM>. As can be seen, the substantially circular annulus section <NUM> of stent <NUM> is disposed within a non-circular native valve annulus <NUM>. At certain locations around the perimeter of prosthetic heart valve <NUM>, gaps <NUM> are formed between the heart valve and native valve annulus <NUM>. Retrograde blood flow through these gaps and around the outside of the valve assembly <NUM> of prosthetic heart valve <NUM> can result in PV leak or regurgitation and other inefficiencies which can reduce cardiac performance. Such improper fitment may be due to suboptimal native valve annulus geometry, for example, as a result of the calcification of the tissue of native valve annulus <NUM> or the presence of unresected native leaflets.

<FIG> illustrates the stent <NUM> of a prosthetic heart valve according to an aspect of the disclosure. <FIG> illustrates a prosthetic heart valve <NUM> that includes the stent <NUM> of <FIG>. Stent <NUM> may be similar or identical to stent <NUM> described above, with certain exceptions. For example, the annulus section <NUM> of stent <NUM> may include three rows of cells <NUM> instead of two rows, although in some embodiments stent <NUM> may include only two rows of cells in the annulus section, or any other number of rows of cells. Although commissure attachment features <NUM> of stent <NUM> are illustrated schematically as open rectangles in <FIG>, the commissure attachment features may have a form similar to commissure attachment features <NUM> shown in <FIG>, or any other suitable form having any number of rows or columns of eyelets and/or eyelets of different sizes and/or shapes positioned in any arrangement on the commissure attachment feature. For example, as shown in <FIG>, commissure attachment features <NUM> may include a single elongated eyelet extending in a circumferential direction on a proximal end portion of the commissure attachment feature, with two rows and two columns of substantially rectangular-shaped eyelets positioned distally of the elongated eyelet. A cuff <NUM> similar or identical to cuff <NUM> may be positioned on the luminal and/or abluminal surface of stent <NUM>. Rather than a scalloped inflow end as with cuff <NUM>, however, cuff <NUM> may have a straight inflow end. As shown in <FIG>, prosthetic heart valve <NUM> may include a valve assembly <NUM> having a plurality of leaflets, similar or identical to those of valve assembly <NUM>, positioned radially inwardly of cuff <NUM> and attached to that cuff.

In order to help minimize or eliminate PV leak, for example through the gaps <NUM> shown in <FIG>, additional material may be coupled to the exterior of stent <NUM> as an outer cuff <NUM>. In the illustrated example, outer cuff <NUM> may have a substantially rectangular shape and may be wrapped around the circumference of stent <NUM> at the inflow end of the stent so as to overlap in the longitudinal direction of the stent with cuff <NUM>. Outer cuff <NUM> may be a single piece of material having a proximal edge <NUM>, two side edges <NUM>, <NUM>, and a distal edge <NUM>. Preferably, the proximal edge <NUM> of outer cuff <NUM> is coupled to stent <NUM> and/or to inner cuff <NUM> at or near the inflow end of the stent, for example by a continuous line of sutures (not shown), with the side edges <NUM> and <NUM> of the outer cuff joined to one another so that retrograde blood flow entering the space between the outer cuff and the inner cuff cannot pass in the retrograde direction beyond the combined cuffs. In order to allow retrograde blood flow to enter the space between outer cuff <NUM> and inner cuff <NUM>, the distal edge <NUM> of the outer cuff may be attached to stent <NUM> and/or to inner cuff <NUM> at locations that are spaced apart in the circumferential direction. The distal edge <NUM> of outer cuff <NUM> may, for example, be sutured to stent <NUM> at attachment points S1 located where each cell <NUM> in the proximalmost row of cells intersects with an adjacent cell in that same row. In the illustrated example, since there are nine cells <NUM> in the proximalmost row, there are nine separate attachment points S1 at which the distal edge <NUM> of outer cuff <NUM> is sutured or otherwise attached to stent <NUM>. Retrograde blood flow around the abluminal surface of stent <NUM> may enter the pocket or space between outer cuff <NUM> and inner cuff <NUM> via the spaces between adjacent attachment points S1. Once retrograde blood flow enters this space, outer cuff <NUM> may tend to billow outwardly, helping to fill any of gaps <NUM> between the prosthetic heart valve and native valve annulus <NUM>. Although the foregoing description uses the term "inner" in connection with cuff <NUM>, that is merely intended to indicate that cuff <NUM> is positioned radially inward of outer cuff <NUM>. Inner cuff <NUM> may be located either on the luminal or abluminal side of stent <NUM>, or on both sides.

Although described as a single piece of material above, outer cuff <NUM> may comprise multiple pieces of material that, when joined together, form a similar shape and provide similar function as described above for the outer cuff. Also, rather than being formed of a single substantially rectangular piece of material that is wrapped around the circumference of stent <NUM>, outer cuff <NUM> may be formed as a continuous annular web without side edges <NUM>, <NUM>. Preferably, outer cuff <NUM> has an axial height measured from its proximal edge <NUM> to its distal edge <NUM> that is approximately half the axial height of a cell <NUM> in the proximalmost row of cells in stent <NUM> as measured along the major axis of the cell between two of its apices when the cell is in an expanded condition. However, outer cuff <NUM> may have other suitable heights, such as the full axial height of a cell <NUM> in the proximalmost row of cells, or more or less than the full axial height of a cell <NUM> in the proximalmost row of cells. Still further, although inner cuff <NUM> and outer cuff <NUM> are described above as separate pieces of material joined to stent <NUM> and to each other, the cuffs may be formed integrally with one another from a single piece of material that is wrapped around the proximal edge of the stent, with the distal edge <NUM> of the outer portion of the cuff joined to the stent and/or to the inner portion of the cuff at attachment points S1 as described above. With this configuration, the proximal edge <NUM> of outer cuff <NUM> does not need to be sutured to stent <NUM>, although it still may be preferable to provide such attachment. Inner cuff <NUM> and outer cuff <NUM> may be formed of the same or different materials, including any suitable biological material or polymer such as, for example, polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE), polyurethane, polyvinyl alcohol, silicone, or combinations thereof.

In operation, prosthetic heart valve <NUM> may be transitioned into a collapsed condition and loaded onto a delivery device for delivery into a patient. Prosthetic heart valve <NUM> may be advanced to the aortic valve of the patient while it is maintained in the collapsed condition, for example by an overlying sheath of the delivery device that radially constrains the prosthetic heart valve. Once at the desired location, such as the native aortic valve, the overlying sheath may be removed from prosthetic heart valve <NUM>, removing the constraining force. In the absence of any constraining forces, prosthetic heart valve <NUM> returns to the expanded condition. During normal operation, if any blood flows in the retrograde direction around the outside of stent <NUM>, that blood may flow into the space between outer cuff <NUM> and inner cuff <NUM>. Blood flowing into the space between inner cuff <NUM> and outer cuff <NUM> may result in the outer cuff billowing outwardly to some degree to further seal any remaining spaces between prosthetic heart valve <NUM> and the native aortic valve annulus, helping to mitigate or eliminate PV leak.

<FIG> illustrates a prosthetic heart valve, for example prosthetic heart valve <NUM> or prosthetic heart valve <NUM>, implanted in the native valve annulus <NUM> of an aortic valve. As shown in <FIG>, the inflow end of the prosthetic heart valve is typically positioned between about <NUM> and about <NUM> below native valve annulus <NUM>. In other words, when the prosthetic heart valve replaces the function of a native aortic valve, the prosthetic heart valve will typically have a sub-annular portion SA that includes about <NUM> to about <NUM> of structure that extends beyond native valve annulus <NUM> in a direction toward the left ventricle. It may be desirable to have sub-annular portion SA extend a distance beyond native valve annulus <NUM> to help assure full contact around the entire annulus section of the stent. For prosthetic heart valve <NUM>, which does not include a second outer cuff as described in connection with prosthetic heart valve <NUM>, the sub-annular portion SA may not pose any particular problems with the operation of the prosthetic heart valve. However, for prosthetic heart valve <NUM>, the sub-annular portion SA may cause certain undesirable results in the functioning of the prosthetic heart valve. As described above, outer cuff <NUM> may tend to at least partially fill with blood and billow outwardly to help prevent PV leak. However, as blood flows into the space between outer cuff <NUM> and inner cuff <NUM>, that blood flow may apply pressure to the inner cuff in a direction radially inwardly toward the center longitudinal axis of prosthetic heart valve <NUM>. Because sub-annular portion SA is at the terminal (inflow) end of the stent, the portions of inner cuff <NUM> and stent <NUM> that are within the sub-annular portion of prosthetic heart valve <NUM> are essentially cantilevered. Thus, when retrograde blood flow enters between outer cuff <NUM> and inner cuff <NUM> and applies pressure in a radially inward direction on the inner cuff, the portion of sub-annular portion SA closest to the terminal (inflow) end of the stent is subject to the largest moment. Thus, the terminal end of the stent will tend to deflect inwardly more than portions of the stent farther away from the terminal end of the stent. The inward deflection of the sub-annular portion SA of stent <NUM> creates an additional mode of loading which may contribute to concerns of stent fatigue. It should be understood that prosthetic heart valves of a particular design are often provided in various sizes to account for the natural variations in size of patients' native heart valves. Given two prosthetic heart valves having the same design as prosthetic heart valve <NUM>, with the exception that one of the prosthetic heart valves is larger than the other, the relatively large prosthetic valve may experience greater deflection in the sub-annular portion SA of the prosthetic heart valve due to this additional mode of loading, which may result in a greater concern of stent fatigue compared to the relatively small prosthetic valve.

In order to reduce the concern of additional stent fatigue due to blood flowing in the retrograde direction into the space between outer cuff <NUM> and inner cuff <NUM>, without changing the positioning of prosthetic heart valve <NUM> relative to native valve annulus <NUM>, the outer cuff may be provided in a modified or elevated position relative to stent <NUM>. <FIG> illustrate a prosthetic heart valve <NUM> according to an embodiment of the disclosure which may be identical or substantially identical to prosthetic heart valve <NUM>, with the exception that outer cuff <NUM> is positioned farther from the inflow end of stent <NUM> compared to the positioning of outer cuff <NUM> with respect to the inflow end of stent <NUM>. Prosthetic heart valve <NUM> may include a stent <NUM> forming a plurality of cells <NUM>, and may include a valve assembly <NUM> including a plurality of leaflets attached to the stent at commissure attachment features <NUM>, an inner cuff <NUM>, and an outer cuff <NUM>. It should be understood that, with the exception of outer cuff <NUM>, the remaining components of prosthetic heart valve <NUM> may be identical to the corresponding components of prosthetic heart valve <NUM> described above and are not described in any further detail herein.

Although the position of outer cuff <NUM> relative to the remainder of prosthetic heart valve <NUM> is different than the position of outer cuff <NUM> relative to the remainder of prosthetic heart valve <NUM>, the outer cuffs themselves may otherwise be substantially the same. For example, outer cuff <NUM> may have a substantially rectangular shape and may be wrapped around the perimeter of stent <NUM> near the inflow end of the stent so as to overlap in the longitudinal direction of the stent with inner cuff <NUM>. Outer cuff <NUM> may be a single piece of material having a proximal edge <NUM>, a distal edge <NUM>, and two side edges, although the side edges may be omitted if the outer cuff takes the form of a continuous wrap of material. However, as with outer cuff <NUM>, outer cuff <NUM> may comprise multiple separate pieces of material that, when joined together, form a similar shape and provide similar function as shown and described herein for the outer cuff. Inner cuff <NUM> and outer cuff <NUM> may be formed of the same or different materials, including any of those described above in connection with inner cuff <NUM> and outer cuff <NUM>.

Rather than coupling proximal edge <NUM> to stent <NUM> and/or inner cuff <NUM> at or near the inflow edge of the stent, the proximal edge of the outer cuff is coupled to the stent and/or the inner cuff at a spaced distance from the inflow end of the stent toward the outflow end of the stent. As shown in <FIG>, this distance may be between about <NUM> and about <NUM> from the inflow edge, which is similar but not necessarily the same as the about <NUM> to about <NUM> length of the sub-annular portion SA.

As with outer cuff <NUM>, the proximal edge <NUM> of outer cuff <NUM> may be coupled to stent <NUM> and/or to inner cuff <NUM>, for example by a continuous line of sutures, so that retrograde blood flow entering the space between the outer cuff and the inner cuff cannot pass in the retrograde direction beyond the combined cuffs. If outer cuff <NUM> includes side edges, those side edges may be coupled to one another prior to, during, or after coupling the outer cuff to stent <NUM> and/or to inner cuff <NUM>. In order to allow retrograde blood flow to enter the space between outer cuff <NUM> and inner cuff <NUM>, the distal edge <NUM> of the outer cuff may be attached to stent <NUM> and/or to inner cuff <NUM> at locations that are spaced apart in the circumferential direction, similar to how outer cuff <NUM> is described and shown in <FIG> as being coupled to stent <NUM> and/or to inner cuff <NUM>. For example, the distal edge <NUM> of outer cuff <NUM> may be sutured to stent <NUM> at attachment points located where each cell <NUM> in the proximalmost row of cells intersects with an adjacent cell in that same row. In the illustrated example, since there are nine cells <NUM> in the proximalmost row, there are nine separate attachment points at which the distal edge <NUM> of outer cuff <NUM> is sutured or otherwise attached to stent <NUM>. Comparing the outer cuff <NUM> of prosthetic heart valve <NUM> shown in <FIG> to the outer cuff <NUM> of prosthetic heart valve <NUM> shown in <FIG>, it should be understood that the attachment of the distal edges of the outer cuffs to the respective stents are substantially identical in terms of positioning, with the main difference being that outer cuff <NUM> has a smaller dimension between its proximal edge <NUM> and its distal edge <NUM> compared to outer cuff <NUM>. As a result, the positions of the openings to the one or more pockets formed between outer cuff <NUM> and inner cuff <NUM> when prosthetic heart valve <NUM> is implanted are substantially identical to the positions of the openings to the one or more pockets formed between outer cuff <NUM> and inner cuff <NUM> when prosthetic heart valve <NUM> is implanted. Thus, the ability for retrograde blood flow around the abluminal surface of stent <NUM> to enter the pocket(s) or space(s) between outer cuff <NUM> and inner cuff <NUM> is substantially unchanged compared to prosthetic heart valve <NUM>. Further, it should be understood that the different dimensions and/or spacing of outer cuff <NUM> compared to inner cuff <NUM> need not result in a significant change in the ability of the outer cuff of prosthetic heart valve <NUM> to billow open to mitigate PV leak compared to the outer cuff of prosthetic heart valve <NUM>. At least one reason for this is that the sub-annular portion SA of outer cuff <NUM> does not significantly contribute to sealing upon entry of blood into the space between the outer cuff and inner cuff <NUM> when it is positioned beyond native valve annulus <NUM>. In other words, eliminating the sub-annular portion SA of outer cuff <NUM>, effectively resulting in the outer cuff <NUM> of prosthetic heart valve <NUM> shown in <FIG>, need not reduce the ability of the outer cuff to mitigate PV leak.

As noted above, the different position and/or geometry of outer cuff <NUM> compared to outer cuff <NUM> need not reduce the ability to mitigate PV leak, but there may be a significant reduction in the forces and/or moments applied on the inflow end of stent <NUM> in the radially inward direction from blood flowing in the retrograde direction around the abluminal surface of the stent into the space(s) between outer cuff <NUM> and inner cuff <NUM>. The reason for the reduction in thee forces can be seen in the force diagrams in <FIG> and <FIG>, and the corresponding representations of the resulting stent deflections shown in <FIG> and <FIG>.

<FIG> show that, as blood flows in the retrograde direction R into the space between inner cuff <NUM> and outer cuff <NUM>, forces F1 act radially inwardly in that area on the inner cuff and thus also the adjacent portions of stent <NUM>, causing an amount of deflection D1. The relatively large deflection of stent <NUM> in the sub-annular portion SA, caused at least in part by a cantilever effect on the free inflow end of the stent, is illustrated by the diagram of <FIG>. On the other hand, as shown in <FIG>, the same retrograde blood flow applies radially inward force F2 over the portion of stent <NUM> spaced away from the terminal inflow edge, resulting in a reduced moment and lessened cantilever effect. While forces F2 may still cause some amount of deflection D2 in the proximalmost end of stent <NUM>, the omission of radial inward forces being applied directly to the sub-annular portion SA of the stent results in a relatively small deflection compared to the deflection D1 expected in stent <NUM> when the remaining conditions are the same.

It should be understood that the forces and deflections shown in <FIG> are not expected to be static due to the pulsatile nature of blood flow. Stated otherwise, as the prosthetic heart valves <NUM>, <NUM> open and close during the cardiac cycle, the forces and deflections shown in <FIG> would be cyclical, occurring while the prosthetic heart valve is in the closed condition and blood attempts to flow in the retrograde direction R between the abluminal surface of the prosthetic valve and the native valve annulus <NUM>. This cyclical nature of the deflection may increase the stresses in stents <NUM>, <NUM> and cause stent fatigue, which may reduce the overall amount of time during which the prosthetic heart valves <NUM>, <NUM> are expected to function properly. The larger deflections D1 that may occur in prosthetic heart valve <NUM> may result in a corresponding shorter lifespan of the prosthetic heart valve compared to that of prosthetic heart valve <NUM>.

It should be understood that the deflections D1 and D2 shown in <FIG> are not intended to be to scale or to otherwise represent actual amounts of deflection, but rather are intended to illustrate schematically that a smaller deflection D2 is expected in stent <NUM> compared to the larger deflection D1 expected in stent <NUM>.

It may be possible to achieve similar or the same results of maintaining a suitable level of PV leak mitigation while reducing deflection-induced stent fatigue in manners other than that described in connection with <FIG>.

Referring now to <FIG>, a prosthetic heart valve <NUM>' is illustrated that is identical to prosthetic heart valve <NUM> with one exception. It should be understood that the part numbers in <FIG> that are identical to the part numbers in <FIG> indicate a similar or identical structure, and thus are not described in any further detail. The difference in prosthetic heart valve <NUM>' is found in outer cuff <NUM>'. Outer cuff <NUM>' may be generally identical in shape, size, and positioning to outer cuff <NUM>, but may be modified to decrease the available space between the outer cuff <NUM>' and inner cuff <NUM> that is available to receive retrograde blood flow therebetween. In the particular embodiment illustrated in <FIG>, one or more sutures (or other fasteners) <NUM>' coupled the outer cuff <NUM>' to the inner cuff <NUM> at positions near the terminal inflow end of the prosthetic heart valve <NUM>'. As illustrated, one suture <NUM>' (or one suture line) is provided for each cell <NUM> in the proximalmost row of cells. Each suture <NUM>' (or each suture line) extends from the terminal inflow end of the outer cuff <NUM>', and curves to reach its highest point near a circumferential center of the corresponding cell <NUM>, at which point the suture <NUM>' (or suture line) curves back down toward the terminal inflow end of the outer cuff <NUM>'. Because the suture <NUM>' couples the outer cuff <NUM>' to the inner cuff <NUM>, the space beneath the suture <NUM>' (or suture line) is not available for blood to flow into. In other words, rather than physically shortening the outer cuff <NUM>' to achieve a structure similar to outer cuff <NUM>, the suture <NUM>' effectively reduces the available area in which blood may flow, achieving a similar or identical effect without altering the height of outer cuff <NUM>. Thus, any retrograde blood flowing into the available space between outer cuff <NUM>' and inner cuff <NUM> will not be able to flow beyond the sutures <NUM>', minimizing the amount of deflection that may be expected at the terminal inflow end of stent <NUM>. It should be understood that a single suture may form the entire suture line <NUM>' extending around the circumference of the stent <NUM>, although more than one suture may be used to form the entirety of the suture line <NUM>'.

In the particular embodiment of outer cuff <NUM>' illustrated in <FIG>, the peak of each suture <NUM>' (or suture line) may generally axially align with the proximal apex of a cell <NUM> in the proximalmost row of cells. However, such alignment is not required, and the sutures <NUM>' (or suture line) may be circumferentially offset compared to the embodiment illustrated in <FIG>. This curved or scalloped shape, however, is not required. For example, a substantially straight suture or suture line may extend circumferentially around stent <NUM>, attaching the outer cuff <NUM>' to the inner cuff <NUM> at a point between about <NUM> and about <NUM> or about <NUM> from the inflow end of stent <NUM>. Still further, sutures <NUM>' are illustrated in <FIG> as being substantially continuous around the circumference of stent <NUM>, but this is not required either. For example, sutures <NUM>' may be strategically positioned to couple outer cuff <NUM>' to inner cuff <NUM> at positions expected to be prone to the greatest amount of deflection. In one example, sutures <NUM>' may be provided on the inflow end of outer cuff <NUM>' in positions axially aligned with, or axially adjacent to, commissures attachment features <NUM>. The areas of inner cuff <NUM> that are aligned with commissure attachment features <NUM> may be relatively high pressure areas, and thus the portions of the terminal inflow end of stent <NUM> that are axially aligned with (or axially adjacent to) the commissure attachment features <NUM> may be most likely to experience the undesirable deflection described above. Thus, reducing the available space between outer cuff <NUM>' and inner cuff <NUM> at positions axially aligned with, or axially adjacent to, commissure attachment features <NUM> may provide similar functionality with fewer sutures <NUM>' (or less total suture material) required.

A prosthetic heart valve substantially similar to prosthetic heart valves <NUM>' and/or <NUM> may be used to replace the functioning of a native pulmonary valve. Similarly, the concepts described above in connection with the structure of outer cuff <NUM>' and/or the positioning of outer cuff <NUM> relative to a native valve annulus may be applied to prosthetic heart valves intended to replace the functioning of either the native mitral valve or native tricuspid valve. Despite these options, the configuration of outer cuff <NUM>' and/or outer cuff <NUM> described above may be most useful in prosthetic heart valves that replace the functioning of the native valve of the left heart, as pressures involved with pumping blood in the left heart are typically significantly larger than forces at the valves of the right heart. However, it should also be understood that modifications may be appropriate if being used for a different valve. For example, if the concepts described above were implemented in a prosthetic mitral valve, certain elements may appropriately be modified to account for the different anatomy in the mitral valve compared to the aortic valve.

Claim 1:
A prosthetic heart valve (<NUM>) for replacing a native valve, comprising:
a stent (<NUM>) extending in a longitudinal direction from an inflow end to an outflow end;
a valve assembly (<NUM>) disposed within the stent;
a first cuff (<NUM>) annularly disposed adjacent the stent; and
a second cuff (<NUM>) having a proximal edge (<NUM>) facing toward the inflow end of the stent and a distal edge (<NUM>) facing toward the outflow end of the stent, the second cuff being annularly disposed about the stent radially outward of the first cuff, the distal edge of the second cuff being coupled to at least one of the first cuff and the stent at a plurality of first locations spaced apart in a circumferential direction of the stent to form at least one pocket between the first cuff and the second cuff, the second cuff being coupled to the first cuff at a plurality of second locations positioned a spaced distance from the inflow end, such that areas proximal to the plurality of second locations between the first and second cuff are sealed against receiving retrograde blood flow therein and such that a sub-annular portion (SA) of the stent extending between the inflow end and the proximal edge of the second cuff is uncovered.