Patent Description:
The present invention relates to collapsible prosthetic heart valves, and more particularly, to prosthetic heart valves having commissure attachment features that reduce strain on the leaflets of the prosthetic valve and methods of manufacturing the commissure attachment features.

Diseased and/or defective heart valves may lead to serious health complications. One method of addressing this condition is to replace a non-functioning heart valve with a prosthetic valve. 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 types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed to reduce its circumferential size.

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 repaired by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and expanded to its full operating size. For balloon-expandable valves, this generally involves releasing the entire 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 For self-expanding valves, on the other hand, the stent automatically expands as the stent is withdrawn from the delivery apparatus.

Properly functioning prosthetic heart valves maintain unidirectional blood flow in the circulatory system by opening and closing, depending on the difference in the pressure on opposite sides of the valve. Prosthetic aortic heart valves prevent backflow from the aorta into the left ventricle during systole.

Despite the improvements that have been made to prosthetic heart valves, various shortcomings remain. For example, prosthetic heart valves have limited life expectancies for a variety of reasons. Thrombus buildup, for example, may prevent the prosthetic leaflets from properly coapting. Moreover, the prosthetic heart valve may be susceptible to failure at high stress regions, such as the leaflet commissure attachment feature, causing the prosthetic leaflets to tear and/or the sutures that attach the prosthetic valve assembly to the stent to tear.

Therefore, there is a need for improvements to the commissure attachment features of prosthetic heart valves that adequately secure the prosthetic leaflets to the stent in a manner that reduces the strain placed on the valve assembly without affecting the prosthetic heart valve's ability to collapse.

<CIT> discloses a prosthetic valve with expandable frame. Some aspects are directed to a diametric taper for the prosthetic valve for achieving enhanced performance of the prosthetic valve under operational conditions, enhanced compressibility and delivery characteristics, and other additional or alternative advantages.

Embodiments not falling within the scope of the claims are exemplary. In accordance with a first aspect of the present invention, a commissure attachment feature extends in a medial direction of a stent for coupling a valve assembly to the stent. Among other advantages, this attachment feature permits adjacent leaflets to be sutured to one another to improve blood washout of the neo-sinus of the prosthetic heart valve to prevent the formation of thrombus, and to redistribute strain from the commissure of the leaflets to the stent. Redistributing the strain in this manner reduces the likelihood that the prosthetic leaflets will tear.

One embodiment of the device includes a stent extending in a longitudinal direction and having a collapsed condition and an expanded condition. The stent includes a plurality of struts forming cells and a plurality of commissure attachment features spaced apart in an annular direction of the stent. Each of the plurality of commissure attachment features has a side attached to the stent and an arcuate edge extending between a first end joined to the side, and a second end spaced from the stent in the medial direction, a spacing of the second end and the stent defining a width of the commissure attachment feature. Each of the commissure attachment features is attached to select ones of the struts and extends in a medial direction of the stent. A valve assembly is secured to the plurality of commissure attachment features, the valve assembly including a cuff and a plurality of leaflets, each of the leaflets having a free edge and being capable of alternating between an open position and a closed position.

A method of manufacturing a prosthetic heart valve is also provided. The method includes cutting a tubular material to form a stent, the stent extending in a longitudinal direction and having a collapsed condition and an expanded condition. The stent includes a plurality of struts forming cells and a plurality of commissure attachment features spaced apart in an annular direction of the stent. Each of the plurality of commissure attachment features has a side attached to the stent and an arcuate edge extending between a first end joined to the side and a second end. The method further includes bending each of the commissure attachment features from a first orientation to a second orientation different from the first orientation, and coupling a valve assembly to the commissure attachment features, the valve assembly including a cuff and a plurality of leaflets, each of the leaflets having a free edge and being capable of alternating between an open position and a closed position. The first orientation is an annular direction of the stent and the second orientation is a medial direction of the stent, so that the second end of the arcuate edge is spaced from the stent in the medial direction, a spacing of the second end and the stent defining a width of the commissure attachment feature.

Various embodiments of the present invention are described herein with reference to the drawings, wherein:.

As used herein, the term "proximal," when used in connection with a prosthetic heart valve, refers to the end of the heart valve closest to the heart when the heart valve is implanted in a patient, whereas the term "distal," when used in connection with a prosthetic heart valve, refers to the end of the heart valve farthest from the heart when the heart valve is implanted in a patient. As used herein, the terms "generally," "substantially," "approximately" and "about" are intended to mean that slight deviations from absolute are included within the scope of the term so modified.

<FIG> illustrates a collapsible prosthetic heart valve <NUM> that is designed to replace the function of the native aortic valve of a patient. Prosthetic heart valve <NUM> includes an expandable stent <NUM> which may be formed from biocompatible materials that are capable of self-expansion, for example, shape memory alloys such as nitinol. Stent <NUM> extends from a proximal or annulus end <NUM> to a distal or aortic end <NUM>, and includes an annulus section <NUM> adjacent the proximal end and an aortic section <NUM> adjacent the distal end. Annulus section <NUM> has a relatively small cross-section in an expanded condition compared to aortic section <NUM> in the expanded condition. Annulus section <NUM> maybe in the form of a cylinder having a substantially constant diameter along its length. A transition section <NUM> tapers outwardly from annulus section <NUM> to aortic section <NUM>. Each of the sections of stent <NUM> includes a plurality of struts <NUM> which form a plurality of cells <NUM> that are connected to one another in one or more annular rows around the stent. Annulus section <NUM> may have two annular rows of complete cells and aortic section <NUM> and transition section <NUM> may each have one or more annular rows of partial cells. The cells in aortic section <NUM> may be larger than the cells in annulus section <NUM>. The larger cells in aortic section <NUM> facilitate positioning prosthetic valve <NUM> within the native aortic annulus such that stent <NUM> does not interfere with blood flow to the coronary arteries.

Stent <NUM> includes one or more retaining elements <NUM> at distal end <NUM>. Retaining elements <NUM> are sized to cooperate with a corresponding retaining structure on a delivery device. This cooperation minimizes axial movement of the prosthetic heart valve relative to the delivery device during unsheathing or resheathing procedures, and prevents rotation of the prosthetic heart valve relative to the delivery device as the delivery device is advanced to the target location and during deployment.

Stent <NUM> may also include a plurality of commissure attachment features <NUM> for attaching the commissure between two adjacent leaflets to the stent. As shown in <FIG>, commissure attachments features <NUM> are disposed within the wall of stent <NUM> and may lie at the intersection of four cells <NUM>, two of the cells being adjacent to 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> are preferably positioned entirely within annulus section <NUM>, or at the juncture of the annulus section and transition section <NUM>. Commissure attachment features <NUM> may include one or more eyelets <NUM> which facilitate the suturing of the leaflet commissure to stent <NUM>.

Prosthetic heart valve <NUM> also includes a valve assembly <NUM>, which may be positioned entirely within annulus section <NUM> and secured to stent <NUM> by suturing the valve assembly to struts <NUM> and/or to commissure attachment features <NUM>. That is, the entire valve assembly <NUM> may be axially positioned between the proximal end <NUM> of stent <NUM> and commissure attachment features <NUM>, such that none of the valve assembly is positioned between the commissure attachment features and the distal end <NUM> of the stent. Valve assembly <NUM> includes a cuff <NUM> and a plurality of leaflets <NUM> which open and close collectively to function as a one-way valve. Both cuff <NUM> and leaflets <NUM> may be wholly or partly formed of any suitable biological material, such as bovine or porcine pericardium, or biocompatible polymers, such as PTFE, urethanes and the like.

Prosthetic heart valve <NUM> may be used to replace a native 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 a collapsed condition. The delivery device may be introduced into a patient using a transfemoral, transapical, transseptal or any other percutaneous approach. Once the delivery device has reached the target site, the user may deploy prosthetic heart valve <NUM>. Upon deployment, prosthetic heart valve <NUM> expands so that the annulus section <NUM> of stent <NUM> is in secure engagement within the native annulus.

<FIG> is a highly schematic cutaway view showing prosthetic heart valve <NUM> disposed within the native aortic annulus of a patient. When prosthetic heart valve <NUM> is properly positioned within the native annulus, it works as a one-way valve, allowing blood to flow from the left ventricle of the heart to the aorta during systole, and preventing blood from flowing in the opposite direction. Long term clinical success, and ultimately the life of prosthetic heart valve <NUM> is dependent, in part, on the ability of the free edges of leaflets <NUM> to properly coapt. Thrombus buildup in the neo-sinus NS of prosthetic heart valve <NUM> may restrict motion of leaflets <NUM> and prevent the leaflets from coapting.

Suturing the commissures of leaflets <NUM> radially inward of the commissure attachments features <NUM> of stent <NUM>, as shown in <FIG>, reduces the cross-sectional area of the lumen of prosthetic heart valve <NUM>, and results in increased velocity of blood flow through the neo-sinus during systole. The increased blood flow velocity is believed to improve blood wash out from the neo-sinus and reduce thrombus build up. However, the addition of sutures S places additional strain on the leaflets <NUM> of valve assembly <NUM> and increases the likelihood that the valve assembly will fail at this junction. Failure may, for example, include tearing of sutures S and/or the leaflets <NUM> of valve assembly <NUM>.

<FIG> illustrates a prosthetic heart valve <NUM> according to an embodiment of the present invention. Prosthetic heart valve <NUM> includes all of the features of prosthetic heart valve <NUM>, except for commissure attachment features <NUM>. Accordingly, each of the features of prosthetic heart valve <NUM> that correspond to features of prosthetic heart valve <NUM> are not described again hereinafter. Instead, when such features are referenced or illustrated in <FIG>, these features are described and illustrated using corresponding <NUM> series numerals.

Prosthetic heart valve <NUM> replaces commissure attachment features <NUM> with commissure attachment features <NUM>, shown in <FIG>. Commissure attachment features <NUM> are designed to redistribute strain from the leaflets <NUM> of prosthetic heart valve <NUM> to the stent <NUM> of the prosthetic heart valve. Commissure attachment features <NUM> are spaced apart from one another in an annular direction of stent <NUM> and disposed within a predetermined one of the annular rows of cells <NUM>. Preferably, commissure attachment features <NUM> are disposed in one of the rows of cells within the annulus section <NUM> of stent <NUM>, or in one of the rows of cells at the juncture of the annulus section and the transition section <NUM> of the stent. Since <FIG> illustrates a prosthetic heart valve <NUM> for replacing a native tricuspid valve, such as the aortic valve, prosthetic heart valve <NUM> is illustrated with three leaflets <NUM>, as well as three commissure attachment features <NUM>. However, it will be appreciated that prosthetic heart valves according to this aspect of the invention may have a greater or lesser number of leaflets <NUM> and/or commissure attachment features <NUM>. For example, if prosthetic heart valve <NUM> were a prosthetic heart valve for replacing a native bicuspid valve, such as a mitral valve, the prosthetic heart valve may include two commissure attachment features <NUM> for attaching each of the two prosthetic leaflets <NUM> to stent <NUM>.

Referring to <FIG>, each one of the plurality of commissure attachment features <NUM> includes a body <NUM> that has a length in a longitudinal direction of stent <NUM>, a width in a radial direction of the stent and a thickness (not shown) in an annular direction of the stent. The width of body <NUM> may be about <NUM> or less, and is preferably between about <NUM> and about <NUM>. Commissure attachment features <NUM> may be positioned above the bulk of leaflets <NUM>. In light of this and that the commissure attachment features have a relatively small dimension in the medial direction of stent <NUM>, the collapsibility of prosthetic heart valve <NUM> is not inhibited. Accordingly, prosthetic heart valve <NUM> can be collapsed into a competitive French delivery system, for example, an <NUM> French delivery device.

The body <NUM> of commissure attachment feature <NUM> has a side <NUM> that is attached to select struts <NUM> of stent <NUM>, and a free edge <NUM> that is disposed in an interior region the stent. That is, the body <NUM> of commissure attachment feature <NUM> extends from select struts <NUM> in a medial direction of stent <NUM> (i.e., toward the middle of the stent or radially inward). In other words, body <NUM> extends orthogonal to the annular direction of stent <NUM> toward the center of the stent. The body <NUM> of commissure attachment feature <NUM> may be shaped as a quarter ellipse, or a quarter circle, such that the free edge <NUM> of the body forms an arc extending from a distal end of the attached side <NUM> of the body to a proximal end of the free edge spaced radially inward from stent <NUM>.

The body <NUM> of commissure attachment feature <NUM> may include a plurality of apertures or eyelets for connecting valve assembly <NUM> to stent <NUM>. Thus, body <NUM> may include an eyelet <NUM> for coupling cuff <NUM> to stent <NUM>, and one or more smaller eyelets <NUM> for suturing adjacent leaflets <NUM> to one another and to the commissure attachment feature. At least one of leaflet attachment eyelets <NUM> may be spaced from the attached side <NUM> of commissure attachment feature <NUM> so as to be spaced from a luminal surface of stent <NUM>.

<FIG> is a flow chart depicting a method <NUM> of manufacturing prosthetic heart valve <NUM>. In a first step <NUM>, a tube of nitinol is placed around a mandrel and cut, preferably by a laser or other technique, to form stent <NUM>. A fragmentary view of stent <NUM> after the tube has been cut and radially expanded is illustrated in <FIG>. As shown, commissure attachment features <NUM> initially extend in a lateral direction relative to the struts <NUM> of stent <NUM>. That is, commissure attachment features <NUM> initially lie within the circumference of stent <NUM>. In a next step <NUM>, the user may bend commissure attachment features <NUM> from their initial positions (e.g., the lateral or circumferential direction) to final positions (e.g., the medial or radial direction) as shown in <FIG>. Commissure attachment features <NUM> are then heat set, or otherwise permanently set, in this position.

After commissure attachment features <NUM> are set in their final positions, cuff <NUM> may be attached to stent <NUM> in step <NUM>, for example, by suturing the cuff to the stent. Although not required, a suture may additionally be pierced through cuff <NUM> and passed through the cuff attachment eyelet <NUM> of commissure attachment feature <NUM> before the suture is again pierced through the cuff. This additional step may optionally be repeated for each one of commissure attachment features <NUM>. The ends of adjacent leaflets may then be sutured together and coupled to the commissure attachment feature <NUM>. In this step <NUM>, a suture may pierce through a first one of the leaflets, pass through at least one of the leaflet attachment eyelets <NUM> of commissure attachment feature <NUM>, and then pierce through an adjacent leaflet. In a final step <NUM>, the belly of each one of leaflets <NUM> may then be sutured to cuff <NUM> and stent <NUM>. In an exemplary embodiment, a series of suture loops extend along the belly of each one of the leaflets in a parabolic shape, and further secure the leaflets to the stent.

By connecting the leaflet commissures to commissure attachment feature <NUM> at a position spaced medially inward from stent <NUM>, the cross-sectional area of the lumen of prosthetic heart valve <NUM> is reduced, such that the velocity of blood flow through the lumen during systole will be increased. As a result of the increased blood flow velocity, some of the blood will form an eddy in the neo-sinus, and wash out from the neo-sinus is improved and thrombus build up is reduced. Moreover, because adjacent leaflets are sutured together via medially extending commissure attachment features <NUM>, when a stress is applied to the prosthetic valve leaflets <NUM>, the stress is transferred away from the prosthetic leaflets to the commissure attachment features and stent <NUM>. This reduces the likelihood that valve assembly <NUM> will fail under stress and prolongs the life of prosthetic heart valve <NUM>.

To summarize the foregoing, a prosthetic heart valve, includes a stent extending in a longitudinal direction and having a collapsed condition and an expanded condition, the stent including a plurality of struts forming cells and a plurality of commissure attachment features spaced apart in an annular direction of the stent, each of the commissure attachment features being attached to select ones of the struts and extending in a medial direction of the stent; and a valve assembly secured to the plurality of the commissure attachment features, the valve assembly including a cuff and a plurality of leaflets, each of the leaflets having a free edge and being capable of alternating between an open position and a closed position; and/or.

A method of manufacturing a prosthetic heart valve is also provided. The method includes cutting a tubular material to form a stent, the stent extending in a longitudinal direction and having a collapsed condition and an expanded condition, the stent including a plurality of struts forming cells and a plurality of commissure attachment features spaced apart in an annular direction of the stent; bending each of the commissure attachment features from a first orientation to a second orientation different from the first orientation; and.

Claim 1:
A prosthetic heart valve (<NUM>), comprising:
a stent (<NUM>) extending in a longitudinal direction and having a collapsed condition and an expanded condition, the stent (<NUM>) including a plurality of struts (<NUM>) forming cells (<NUM>) and a plurality of commissure attachment features (<NUM>) spaced apart in an annular direction of the stent (<NUM>), characterized in that each of the plurality of commissure attachment (<NUM>) features having a side attached to the stent (<NUM>) and an arcuate edge extending between a first end (<NUM>) joined to the side, and a second end (<NUM>) spaced from the stent in the medial direction, a spacing of the second end (<NUM>) and the stent (<NUM>) defining a width of the commissure attachment feature (<NUM>), each of the commissure attachment features (<NUM>) being attached to select ones of the struts (<NUM>) and extending in a medial direction of the stent (<NUM>); and
a valve assembly (<NUM>) secured to the plurality of the commissure attachment features (<NUM>), the valve assembly (<NUM>) including a cuff (<NUM>) and a plurality of leaflets (<NUM>), each of the leaflets (<NUM>) having a free edge and being capable of alternating between an open position and a closed position.