US 20050267573 A9
Devices, systems and methods supplement, repair, or replace a native heart valve. The devices, systems, and methods employ an implant that, in use, extends adjacent a valve annulus. The implant includes a mobile neoleaflet element that occupies the space of at least a portion of one native valve leaflet. The implant mimics the one-way valve function of a native leaflet, to resist or prevent retrograde flow. The implant restores normal coaptation of the leaflets to resist retrograde flow, thereby resisting eversion and/or prolapse, which, in turn, reduces regurgitation.
1. An implant that supplements, repairs, or replaces a native heart valve leaflet or leaflets comprising
a scaffold sized and configured to rest adjacent all or a portion of a native heart valve annulus, at least a portion of the scaffold defining a pseudo-annulus,
a neoleaflet element coupled to the scaffold within pseudo-annulus and being sized and shaped to occupy the space of at least a portion of one native heart valve leaflet to provide a one-way valve function that, in response to a first pressure condition, assumes a valve opened condition within the pseudo-annulus and, in response to a second pressure condition, assumes a valve closed condition within the pseudo-annulus, and
spaced-apart struts appended to the scaffold and being sized and configured to contact tissue near or within the heart valve annulus to brace the scaffold against migration within the annulus during the one-way valve function.
2. An implant according to
wherein the scaffold comprises a wire-form structure.
3. An implant according to
wherein at least one of the struts comprises a wire-form structure.
4. An implant according to
wherein the scaffold and the struts each comprises a wire-form structure.
5. An implant according to
wherein the neoleaflet element includes a bridge appended to the scaffold.
6. An implant according to
wherein the neoleaflet element includes a material covering the bridge.
7. An implant according to
wherein the bridge is a wire-form structure.
8. An implant according to
wherein the neoleaflet element includes a duckbill valve within the psuedo-annulus.
9. An implant according to
wherein the neoleaflet element includes a membrane within the pseudo-annulus.
10. An implant according to
wherein the neoleaflet element is sized and configured to coapt with a native leaflet when in the valve closed condition.
11. An implant according to
wherein the scaffold, neoleaflet element, and the struts are collapsible for placement within a catheter.
12. An implant according to
wherein at least one of the struts carries a structure sized and configured to increase a surface area of contact with tissue at, above, or below the annulus.
13. An implant according to
further including at least one structure appended to the scaffold and being sized and configured to contact tissue at, above, or below the heart valve annulus to stabilize the scaffold.
14. An implant according to
wherein the scaffold, neoleaflet element, and struts include materials and shapes to provide a spring-like bias for compliance with anatomy near or within the heart valve annulus.
15. An implant according to
wherein the struts apply tension to tissue.
16. An implant according to
wherein the struts apply tension to tissue to reshape the heart valve annulus.
17. An implant according to
wherein the struts apply tension to separate tissue along an axis of the heart valve annulus.
18. An implant according to
further including a second heart valve treatment element appended to the scaffold to affect a heart valve function.
19. An implant according to
wherein the second heart valve treatment element includes means for reshaping the heart valve annulus for leaflet coaptation.
20. An implant according to
wherein the second heart valve treatment element includes means for stretching leaftlet commissures for leaflet coaptation.
21. A method for supplementing, repairing, or replacing a native heart valve leaflet or leaflets comprising the steps of
introducing an implant as defined in
providing a one-way valve function that, in response to a first pressure condition, assumes a valve opened condition and, in response to second pressure condition, assumes a valve closed condition by locating the scaffold as defined in
22. A method according to
wherein the introducing step comprises using an open heart surgical procedure.
23. A method according to
wherein the introducing step comprises using a surgical procedure in which the implant is carried within a catheter.
24. A method according to
wherein the introducing step comprises using an intravascular surgical procedure.
This application claims the benefit of co-pending U.S. patent application Ser. No. 09/666,617, filed Sep. 20, 2000 and entitled “Heart Valve Annulus Device and Methods of Using Same,” which is incorporated herein by reference. This application also claims the benefit of Patent Cooperation Treaty Application Ser. No. PCT/US 02/31376, filed Oct. 1, 2002 and entitled “Systems and Devices for Heart Valve Treatments,” which claimed the benefit of U.S. Provisional Patent Application Ser. No. 60/326,590, filed Oct. 1, 2001, which are incorporated herein by reference. This application also claims the benefit of U.S. Provisional Application Ser. No. 60/429,444, filed Nov. 26, 2002, and entitled “Heart Valve Remodeling Devices;” U.S. Provisional Patent Application Ser. No. 60/429,709, filed Nov. 26, 2002, and entitled “Neo-Leaflet Medical Devices;” and U.S. Provisional Patent Application Ser. No. 60/429,462, filed Nov. 26, 2002, and entitled “Heart Valve Leaflet Retaining Devices,” which are each incorporated herein by reference.
The invention is directed to devices, systems, and methods for improving the function of a heart valve, e.g., in the treatment of mitral valve regurgitation.
I. The Anatomy of a Healthy Heart
The heart (see
The heart has four chambers, two on each side—the right and left atria, and the right and left ventricles. The atria are the blood-receiving chambers, which pump blood into the ventricles. A wall composed of membranous and muscular parts, called the interatrial septum, separates the right and left atria. The ventricles are the blood-discharging chambers. A wall composed of membranous and muscular parts, called the interventricular septum, separates the right and left ventricles.
The synchronous pumping actions of the left and right sides of the heart constitute the cardiac cycle. The cycle begins with a period of ventricular relaxation, called ventricular diastole. The cycle ends with a period of ventricular contraction, called ventricular systole.
The heart has four valves (see
At the beginning of ventricular diastole (i.e., ventricular filling)(see
The opening and closing of heart valves occur primarily as a result of pressure differences. For example, the opening and closing of the mitral valve occurs as a result of the pressure differences between the left atrium and the left ventricle. During ventricular diastole, when ventricles are relaxed, the venous return of blood from the pulmonary veins into the left atrium causes the pressure in the atrium to exceed that in the ventricle. As a result, the mitral valve opens, allowing blood to enter the ventricle. As the ventricle contracts during ventricular systole, the intraventricular pressure rises above the pressure in the atrium and pushes the mitral valve shut.
The mitral valve consists of two leaflets, an anterior leaflet 110, and a posterior leaflet 115, attached to chordae tendineae 120 (or chords), which in turn are connected to papillary muscles 130 within the left atrium 140. Typically, the mitral valve has a D-shaped anterior leaflet 110 oriented toward the aortic valve, with a crescent shaped posterior leaflet 115. The leaflets intersect with the atrium 170 at the mitral annulus 190.
In a healthy heart, these muscles and their chords support the mitral and tricuspid valves, allowing the leaflets to resist the high pressure developed during contractions (pumping) of the left and right ventricles. In a healthy heart, the chords become taut, preventing the leaflets from being forced into the left or right atria and everted. Prolapse is a term used to describe the condition wherein the coaptation edges of each leaflet initially may coapt and close, but then the leaflets rise higher and the edges separate and the valve leaks. This is normally prevented by contraction of the papillary muscles and the normal length of the chords. Contraction of the papillary muscles is simultaneous with the contraction of the ventricle and serves to keep healthy valve leaflets tightly shut at peak contraction pressures exerted by the ventricle.
II. Characteristics and Causes of Mitral Valve Dysfunction
Valve malfunction can result from the chords becoming stretched, and in some cases tearing. When a chord tears, the result is a flailed leaflet. Also, a normally structured valve may not function properly because of an enlargement of the valve annulus pulling the leaflets apart. This condition is referred to as a dilation of the annulus and generally results from heart muscle failure. In addition, the valve may be defective at birth or because of an acquired disease, usually infectious or inflammatory.
As a result of regurgitation, “extra” blood back flows into the left atrium. During subsequent ventricular diastole (when the heart relaxes), this “extra” blood returns to the left ventricle, creating a volume overload, i.e., too much blood in the left ventricle. During subsequent ventricular systole (when the heart contracts), there is more blood in the ventricle than expected. This means that: (1) the heart must pump harder to move the extra blood; (2) too little blood may move from the heart to the rest of the body; and (3) over time, the left ventricle may begin to stretch and enlarge to accommodate the larger volume of blood, and the left ventricle may become weaker.
Although mild cases of mitral valve regurgitation result in few problems, more severe and chronic cases eventually weaken the heart and can result in heart failure. Mitral valve regurgitation can be an acute or chronic condition. It is sometimes called mitral insufficiency.
III. Prior Treatment Modalities
In the treatment of mitral valve regurgitation, diuretics and/or vasodilators can be used to help reduce the amount of blood flowing back into the left atrium. An intra-aortic balloon counterpulsation device is used if the condition is not stabilized with medications. For chronic or acute mitral valve regurgitation, surgery to repair or replace the mitral valve is often necessary.
To date, invasive, open heart surgical approaches have been used to repair or replace the mitral valve with either a mechanical valve or biological tissue (bioprosthetic) taken from pigs, cows, or horses.
The need remains for simple, cost-effective, and less invasive devices, systems, and methods for treating dysfunction of a heart valve, e.g., in the treatment of mitral valve regurgitation.
The invention provides devices, systems and methods that supplement, repair, or replace a native heart valve leaflet. The devices, systems, and methods include an implant that, in use, rests adjacent a valve annulus. The implant defines a pseudo-annulus. The implant includes a neoleaflet element that occupies the space of at least a portion of one native valve leaflet. The implant allows the native leaflets to coexist with the implant, or if desired or indicated, one or more native leaflets can be removed and replaced by the implant. The neoleaflet element of the implant is shaped and compressed to mimic the one-way valve function of a native leaflet. The implant includes spaced-apart struts that are sized and configured to contact tissue near or within the heart valve annulus to brace the implant against migration within the annulus during the one-way valve function.
Other features and advantages of the invention shall be apparent based upon the accompanying description, drawings, and claims.
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention, which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.
In its most basic form, the implant 400 is made—e.g., by machining, bending, shaping, joining, molding, or extrusion—from a biocompatible metallic or polymer material, or a metallic or polymer material that is suitably coated, impregnated, or otherwise treated with a material to impart biocompatibility, or a combination of such materials. The material is also desirably radio-opaque to facilitate fluoroscopic visualization.
The base 420 supports a bridge 430 that extends into the valve. The bridge 430 is sized and configured (see
Together, the bridge 430 and the spanning material 410 comprise a neoleaflet element 470 coupled to the base 420. The neoleaflet element 470 may be rigid, semi-rigid, or flexible. The neoleaflet element 470 is coupled to the base 420 in a manner that exerts a mechanical, one-way force to provide a valve function that responds to differential pressure conditions across the neoleaflet element. In response to one prescribed differential pressure condition, the neoleaflet element 470 will deflect and, with a native leaflet, assume a valve opened condition. In response to another prescribed pressure condition, the neoleaflet element 470 will resist deflection and, by coaptation with a native leaflet (or a companion neoleaflet element) at, above, or below the annulus plane, maintain a valve closed condition.
In the context of the illustrated embodiment (when installed in a mitral valve annulus), the neoleaflet element resists being moved in the cranial (superior) direction (into the atrium), when the pressure in the ventricle exceeds the pressure in the atrium—as it would during ventricular systole. The neoleaflet element 470 may move, however, in the caudal (inferior) direction (into the ventricle), when the pressure in the ventricle is less than the pressure in the atrium—as it would during ventricular diastole. The neoleaflet element 470 thereby mimics the one-way valve function of a native leaflet, to prevent retrograde flow.
The implant 400 is sized and shaped so that, in use adjacent the valve annulus of the mitral valve, it keeps the native valve leaflet closed during ventricular systole (as shown in
The functional characteristics of the implant 400 just described can be imparted to the neoleaflet element 470 in various ways. For example, hinges and springs (mechanical or plastic) can be used to couple the bridge to the base. Desirably, the implant 400 is made from materials that provide it with spring-like characteristics.
As shown in
More particularly, in the illustrated mitral valve embodiment, when greater pressure exists superior to the bridge 430 than inferior to the bridge (i.e., during ventricular diastole), the shape and material properties of the bridge 430 accommodate its deflection into the ventricle—i.e., an opened valve condition (as
The implant 400 may be delivered percutaneously, thoracoscopically through the chest, or using open heart surgical techniques. If delivered percutaneously, the implant 400 may be made from a superelastic material (for example superelastic Nitinol alloy) enabling it to be folded and collapsed such that it can be delivered in a catheter, and will subsequently self-expand into the desired shape and tension when released from the catheter.
For example, percutaneous vascular access can be achieved by conventional methods into the femoral or jugular vein. As
The distal end of the catheter 58 encloses an implant 400, like that shown in
The implant 400 may be fixed to the annulus in various ways. For example, the implant 400 may be secured to the annulus with sutures or other attachment means (i.e. barbs, hooks, staples, etc.) Also, the implant 400 may be secured with struts or tabs 450 (see
In this arrangement, the struts 450 are desirably sized and configured to contact tissue near or within the heart valve annulus to brace the base 420 against migration within the annulus during the one-way valve function of the neoleaflet element. In this arrangement, it is also desirable that the base 420 be “elastic,” i.e., the material of the base 420 is selected to possess a desired spring constant. This means that the base 420 is sized and configured to possess a normal, unloaded, shape or condition (shown in
As the preceding disclosure demonstrates, different forms of heart valve treatment can be performed using a single implant.
Implants having one or more of the technical features just described, to thereby function in situ as a neo-leaflet, may be sized and configured in various ways. Various illustrative embodiments will now be described.
In addition, the implant 600 includes an orientation and stabilization framework 610 that may extend from the annulus to the atrial dome. In
Preferably the framework 610 does not interfere with atrial contractions, but instead is compliant enough to contract with the atrium. As such, the implant 600 may have nonuniform flexibility to improve its function within the heart.
As can be seen, a given implant may carry various structures or mechanisms to enhance the anchorage and stabilization of the implant in the heart valve annulus. The mechanisms may be located below the plane of the annulus, to engage infra-annular heart tissue adjoining the annulus in the ventricle, and/or be located at or above the plane of the annulus, to engage tissue on the annulus or in the atrium. These mechanisms increase the surface area of contact between the implant and tissue. A given implant can also include tissue in-growth surfaces, to provide an environment that encourages the in-growth of neighboring tissue on the implant. Once in-growth occurs, the implant becomes resistant to migration or dislodgment from the annulus. Conventional in-growth materials such as polyester fabric can be used.
In this embodiment, the duckbill valve 1210 replaces the native anterior and posterior leaflets. The duckbill valve 1210 serves as dual neo-leaflets, which mutually open and close in response to changes in pressure, replacing the function of the native leaflets.
When the implant 1200 is used to replace a mitral valve (see
While the new devices and methods have been more specifically described in the context of the treatment of a mitral heart valve, it should be understood that other heart valve types can be treated in the same or equivalent fashion. By way of example, and not by limitation, the present systems and methods could be used to prevent or resist retrograde flow in any heart valve annulus, including the tricuspid valve, the pulmonary valve, or the aortic valve. In addition, other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The specification and examples should be considered exemplary and merely descriptive of key technical features and principles, and are not meant to be limiting. The true scope and spirit of the invention are defined by the following claims. As will be easily understood by those of ordinary skill in the art, variations and modifications of each of the disclosed embodiments can be easily made within the scope of this invention as defined by the following claims.