DEVICE AND METHOD FOR REPLACING MITRAL VALVE
A prosthetic mitral valve assembly and method of inserting the same is disclosed. In certain disclosed embodiments, the prosthetic mitral valve assembly has a flared upper end and a tapered portion to fit the contours of the native mitral valve. The prosthetic mitral valve assembly can include a stent or outer support frame with a valve mounted therein, The assembly can be adapted to expand radially outwardly and into contact with the native tissue to create a pressure fit. One embodiment of a method includes positioning the mitral valve assembly below the annulus such that the annulus itself can restrict the assembly from moving in an upward direction towards the left atrium. The mitral valve assembly is also positioned so that the leaflets of the mitral valve hold the assembly to prevent downward movement of the assembly towards the left ventricle.
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The present disclosure concerns a prosthetic mitral heart valve and a method for implanting such a heart valve.
BACKGROUNDProsthetic cardiac valves have been used for many years to treat cardiac valvular disorders. The native heart valves (such as the aortic, pulmonary and mitral valves) serve critical functions in assuring the forward flow of an adequate supply of blood through the cardiovascular system. These heart valves can be rendered less effective by congenital, inflammatory or infectious conditions. Such damage to the valves can result in serious cardiovascular compromise or death. For many years the definitive treatment for such disorders was the surgical repair or replacement of the valve during open heart surgery, but such surgeries are prone to many complications. More recently a transvascular technique has been developed for introducing and implanting a prosthetic heart valve using a flexible catheter in a manner that is less invasive than open heart surgery.
In this technique, a prosthetic valve is mounted in a crimped state on the end portion of a flexible catheter and advanced through a blood vessel of the patient until the valve reaches the implantation site. The valve at the catheter tip is then expanded to its functional size at the site of the defective native valve such as by inflating a balloon on which the valve is mounted.
Another known technique for implanting a prosthetic aortic valve is a transapical approach where a small incision is made in the chest wall of a patient and the catheter is advanced through the apex (i.e., bottom tip) of the heart. Transapical techniques are disclosed in U.S. Patent Application Publication No. 2007/0112422, which is hereby incorporated by reference. Like the transvascular approach, the transapical approach includes a balloon catheter having a steering mechanism for delivering a balloon-expandable prosthetic heart valve through an introducer to the aortic annulus. The balloon catheter includes a deflecting segment just proximal to the distal balloon to facilitate positioning of the prosthetic heart valve in the proper orientation within the aortic annulus.
The above techniques and others have provided numerous options for high-risk patients with aortic valve stenosis to avoid the consequences of open heart surgery and cardiopulmonary bypass. While procedures for the aortic valve are well-developed, such procedures are not necessarily applicable to the mitral valve.
Mitral valve repair has increased in popularity due to its high success rates, and clinical improvements noted after repair. However, a significant percentage (i.e., about 33%) of patients still receive open-heart surgical mitral valve replacements due to calcium, stenosis, or anatomical limitations. There are a number of technologies aimed at making mitral repair a less invasive procedure. These technologies range from iterations of the Alfieri stitch procedure to coronary sinus-based modifications of mitral anatomy to subvalvular placations or ventricular remodeling devices, which would incidently correct mitral regurgitation.
However, for mitral valve replacement, few less-invasive options are available. There are approximately 60,000 mitral valve replacements (MVR) each year and it is estimated that another 60,000 patients should receive MVR, but are denied the surgical procedure due to risks associated with the patient's age or other factors. One potential option for a less invasive mitral valve replacement is disclosed in U.S. Patent Application 2007/0016286 to Herrmann. However, the stent disclosed in that application has a claw structure for attaching the prosthetic valve to the heart. Such a claw structure could have stability issues and limit consistent placement of a transcatheter mitral replacement valve.
Accordingly, further options are needed for less-invasive mitral valve replacement.
SUMMARYA prosthetic mitral valve assembly and method of inserting the same is disclosed.
In certain disclosed embodiments, the prosthetic mitral valve assembly has a flared upper end and a tapered portion to fit the contours of the native mitral valve. The prosthetic mitral valve assembly can include a stent or outer support frame with a valve mounted therein. The assembly is adapted to expand radially outwardly and into contact with the native tissue to create a pressure fit. With the mitral valve assembly properly positioned, it will replace the function of the native valve.
In other embodiments, the mitral valve assembly can be inserted above or below an annulus of the native mitral valve. When positioned below the annulus, the mitral valve assembly is sized to press into the native tissue such that the annulus itself can restrict the assembly from moving in an upward direction towards the left atrium. The mitral valve assembly is also positioned so that the native leaflets of the mitral valve are held in the open position.
In still other embodiments, when positioned above the annulus, prongs or other attachment mechanisms on an outer surface of the stent may be used to resist upward movement of the mitral valve assembly. Alternatively (or in addition), a tether or other anchoring member can be attached to the stent at one end and secured to a portion of the heart at another end in order to prevent movement of the mitral valve assembly after implantation. A tether may also be used to decrease the stress on the leaflets of the replacement valve and/or to re-shape the left ventricle.
In still other embodiments, the prosthetic mitral valve assembly can be inserted using a transapical procedure wherein an incision is made in the chest of a patient and in the apex of the heart. The mitral valve assembly is mounted in a compressed state on the distal end of a delivery catheter, which is inserted through the apex and into the heart. Once inside the heart, the valve assembly can be expanded to its functional size and positioned at the desired location within the native valve. In certain embodiments, the valve assembly can be self-expanding so that it can expand to its functional size inside the heart when advanced from the distal end of a delivery sheath. In other embodiments, the valve assembly can be mounted in a compressed state on a balloon of the delivery catheter and is expandable by inflation of the balloon.
These features and others of the described embodiments will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.
FIG, 4 is an enlarged cross-sectional view of a heart with an embodiment of the mitral valve assembly implanted below an annulus of the native mitral valve.
As used herein, the singular forms “a,” “an,” and “the” refer to one or more than one, unless the context clearly dictates otherwise.
As used herein, the term “includes” means “comprises.” For example, a device that includes or comprises A and B contains A and B but can optionally contain C or other components other than A and B. A device that includes or comprises A or B may contain A or B or A and B, and optionally one or more other components such as C.
In other embodiments, the stent 10 can be a balloon-expandable stent. In such a case, the stent can be formed from stainless steel or any other suitable materials. The balloon-expandable stent can be configured to be crimped to a reduced diameter and placed over a deflated balloon on the distal end portion of an elongate balloon catheter, as is well-understood in the art.
The flared end 14 of the stent 10 helps to secure the stent above or below the annulus of the native mitral valve (depending on the procedure used), while the tapered portion is shaped for being held in place by the native leaflets of the mitral valve.
The valve 18 can be made from biological matter, such as natural tissue, pericardial tissue (e.g., bovine, porcine or equine pericadium), a harvested natural valve, or other biological tissue. Alternatively, the valve can be made from biocompatible synthetic materials (e.g., biocompatible polymers), which are well known in the art. The valve can he shaped to fit the contours of the stent so as to have a flared upper end portion having an upper circumference larger than a lower circumference at the lower end of the valve. Blood flow through the valve proceeds in a direction from the upper portion 12 to the lower portion 16, as indicated by arrow 22 (
Contraction of the left ventricle 28 forces blood through the left ventricular outflow tract and into the aorta 32. The aortic valve 34 is located between the left ventricle 28 and the aorta 32 for ensuring that blood flows in only one direction (i.e., from the left ventricle to the aorta). As used herein, the left ventricular outflow tract (LVOT) is intended to generally include the portion of the heart through which blood is channeled from the left ventricle to the aorta.
On the right side of the heart, the tricuspid valve 40 is located between the right atrium 42 and the right ventricle 44. The right atrium 42 receives blood from the superior vena cava 46 and the inferior vena cava 48. The superior vena cava 46 returns de-oxygenated blood from the upper part of the body and the inferior vena cava 48 returns de-oxygenated blood from the lower part of the body. The right atrium 42 also receives blood from the heart muscle itself via the coronary sinus. The blood in the right atrium 42 enters into the right ventricle 44 through the tricuspid valve 40. Contraction of the right ventricle forces blood through the right ventricle outflow tract and into the pulmonary arteries. The pulmonic valve 50 is located between the right ventricle 44 and the pulmonary trunk for ensuring that blood flows in only one direction from the right ventricle to the pulmonary trunk.
The left and right sides of the heart are separated by a wall generally referred to as the septum 52. The portion of the septum that separates the two upper chambers (the right and left atria) of the heart is termed the artial (or interatrial) septum while the portion of the septum that lies between the two lower chambers (the right and left ventricles) of the heart is called the ventricular (or interventricular) septum. A healthy heart has a generally conical shape that tapers from a base to an apex 54.
As shown in
When properly positioned, the valve assembly avoids or at least minimizes paravalvular leakage. In tests performed on a porcine heart, approximately two pounds of force or greater were applied to stents in the left atrial direction with little or no dislodgement, movement or disorientation.
First, an incision is made in the chest of a patient and in the apex 54 of the patient's heart. A guide wire 120 is inserted through the apex 54 and into the left ventricle. The guide wire 120 is then directed up through the mitral valve 24 and into the left atrium 26. An introducer 122 is advanced over the guide wire into the left atrium (see
In
Alternatively, the mitral valve assembly can be fully expanded directly in place at the implantation site by first aligning the valve assembly at the implantation site and then retracting the introducer relative to the delivery catheter to allow the entire valve assembly to expand to its functional size. In this case, there is no need to pull the mitral valve assembly down into the implantation site. Additional details of the transapical approach are disclosed in U.S. Patent Application Publication No. 2007/0112422 (mentioned above).
In another embodiment, the valve assembly 20 can be mounted on an expandable balloon of a delivery catheter and expanded to its functional size by inflation of the balloon. When using a balloon catheter, the valve assembly can be advanced from the introducer to initially position the valve assembly in the left atrium 26. The balloon can be inflated to fully expand the valve assembly. The delivery catheter can then be retracted to pull the expanded valve assembly into the desired implantation site (e.g., just below the annulus of the native valve). In another embodiment, the balloon initially can be partially inflated to partially expand the valve assembly in the left atrium. The delivery catheter can then be retracted to pull the partially expanded valve into the implantation site, after which the valve assembly can be fully expanded to its functional size.
Mitral regurgitation can occur over time due to the lack of coaptation of the leaflets in the prosthetic mitral valve assembly. The lack of coaptation in turn can lead to blood being regurgitated into the left atrium, causing pulmonary congestion and shortness of breath. To minimize regurgitation, the leaflets of the valve assembly can be connected to one or more tension members that function as prosthetic chordae tendinae.
In particular embodiments, the anchor member 174 can have a plurality of prongs that can grab, penetrate, and/or engage surrounding tissue to secure the device in place. The prongs of the anchor member 174 can be formed from a shape memory material to allow the anchor member to be inserted into the heart in a radially compressed state (e.g., via an introducer) and expanded when deployed inside the heart. The anchor member can be formed to have an expanded configuration that conforms to the contours of the particular surface area of the heart where the anchor member is to be deployed, such as described in co-pending application Ser. No. 11/750,272, published as US 2007/0270943 A1, which is incorporated herein by reference. Further details of the structure and use of the anchor member are also disclosed in co-pending application Ser. No. 11/695,583 to Rowe, filed Apr. 2, 2007, which is incorporated herein by reference.
Alternative attachment locations in the heart are possible, such as attachment to the papillary muscle (not shown). In addition, various attachment mechanisms can be used to attach tension members to the heart, such as a barbed or screw-type anchor member. Moreover, any desired number of tension members can be attached to each leaflet (e.g., 1, 2, 3 . . . et.). Further, it should be understood that tension members (e.g., tension members 160 or 170) can be used on any of the embodiments disclosed herein.
As discussed above,
Although groups of three tension members are illustrated, other connection schemes can be used. For example, each group can include any desired number of tension members (e.g., 1, 2, 3, . . . etc.). Additionally, the tension members can connect to any portion of the stent 194 and at spaced intervals, if desired. Likewise, the tension members can connect to the leaflets at a point of convergence, rather than at spaced intervals. Further, the tension members can be used on bicuspid or tricuspid valves. Still farther, it should be understood that tension members extending between the stent and the leaflets can be used on any of the embodiments disclosed herein.
Having illustrated and described the principles of the illustrated embodiments, it will be apparent to those skilled in the art that the embodiments can be modified in arrangement and detail without departing from such principles.
Although the transapical procedure shown in
Further, although the mitral valve assembly 20 is shown generally circular in cross section, as noted above, it can have a D-shape, an oval shape or any other shape suitable for fitting the contours of the native mitral valve. Furthermore, although the mitral valve assembly is shown as having a flared upper end, other embodiments are contemplated, such as, for example, wherein the stent is flared at both ends or has a substantially cylindrical shape. Furthermore, the stent may be coated to reduce the likelihood of thrombi formation and/or to encourage tissue ingrowth using coatings known in the art. Still further, it is contemplated that the stent may be replaced with an alternative structure, such as an expandable tubular structure, which is suitable for anchoring the prosthetic valve member in the heart.
Still further, although a transapical procedure is described in detail in
In view of the many possible embodiments, it will be recognized that the illustrated embodiments include only examples of the invention and should not be taken as a limitation on the scope of the invention. Rather, the invention is defined by the following claims. We therefore claim as the invention all such embodiments that come within the scope of these claims.
Claims
1. A prosthetic mitral valve assembly, comprising:
- a radially-expandable stent including a first portion sized to be held in place by leaflets of a native mitral valve and a second portion having a flared end, the flared end sized to implant above or below an annulus of the mitral valve with a pressure or friction fit, wherein the stent tapers from the flared end to an opposite end of the stent; and
- a valve portion coupled to the stent
2. The prosthetic mitral valve assembly of claim 1, wherein the mitral valve assembly is adapted to expand into contact with the native mitral valve tissue to create the pressure or friction fit and secure the mitral valve assembly in a fixed position in the heart.
3. The prosthetic mitral valve assembly of claim 1, wherein the valve portion includes a bicuspid or tricuspid valve.
4. The prosthetic mitral valve assembly of claim 3, wherein the bicuspid valve includes two leaflets that differ in size.
5. The prosthetic mitral valve assembly of claim 4, further including tension members coupled between the leaflets and the stent.
6. The prosthetic mitral valve assembly of claim 5, wherein the tension members are coupled at different heights, relative to one another, along a length of the stent.
7. The prosthetic mitral valve assembly of claim 1, wherein the stent has a truncated conical shape.
8. The prosthetic mitral valve assembly of claim 1 wherein the stent includes a non-uniform, cross-sectional shape conforming to the native mitral valve.
9. The prosthetic mitral valve assembly of claim 1, wherein the flared end is scalloped.
10. The prosthetic mitral valve assembly of claim 1, wherein the prosthetic mitral valve assembly is held in place without clamping onto tissue surrounding the assembly.
11. The prosthetic mitral valve assembly of claim 1, wherein the stent includes external prongs to assist in holding the prosthetic mitral valve assembly in place.
12. The prosthetic mitral valve assembly of claim 1, wherein the stent and the valve portion are collapsible to a reduced diameter for insertion into the heart on a delivery catheter for implantation.
13. The prosthetic mitral valve assembly of claim 1, further including a tether coupled to the stent on one end thereof the tether being configured to couple the stent to a portion of the heart remote from the stent.
14. The prosthetic mitral valve assembly of claim 11 wherein the valve portion further includes prosthetic leaflets and further including tension members coupled to the prosthetic leaflets for preventing the prosthetic leaflets from everting and reducing stresses induced by ventricular contraction.
15. The prosthetic mitral valve assembly of claim 14, wherein the tension members are coupled to the prosthetic leaflets at a first end of the tension members and coupled at an opposite end to the stent or to a patient's heart.
16. The prosthetic mitral valve assembly of claim 14, wherein the tension members are coupled to the stent at a first end of the tension members and coupled at an opposite end to a portion of the patient's heart.
17. A method of implanting a prosthetic mitral heart valve, comprising:
- inserting a prosthetic mitral valve assembly in a collapsed state into a heart using a delivery catheter;
- expanding the mitral valve assembly; and
- positioning the mitral valve assembly within a native valve so that solely pressure exerted radially outward by the mitral valve assembly holds the mitral valve assembly in position;
- wherein positioning the mitral valve assembly includes pulling the mitral valve assembly from the left atrium so that a flared end of the mitral valve assembly sits below an annulus of the native mitral valve and wherein the mitral valve assembly is held in place solely through radial outward pressure from the mitral valve assembly and contact between the native mitral valve leaflets and the outer surface of the valve assembly.
18. The method of claim 17, wherein inserting includes inserting the catheter through an apex of the heart into the left ventricle, through the mitral valve and into the left atrium.
19. An apparatus for replacement of a mitral valve, comprising:
- a stent having an upper end, a lower end, and an aperture there through extending from the upper to the lower end;
- a valve having a plurality of leaflets mounted within the stent; and
- at least one tension member connected at one end to at least one of the leaflets and connected at another end to the stent to lessen the amount of stress transferred to the at least one leaflet.
20. The apparatus of claim 19, wherein the stent has prongs on an outer surface thereof to assist in securing the stent when in contact with native tissue.
21. The apparatus of claim 19, wherein the valve is bicuspid or tricuspid.
22. The apparatus of claim 19, wherein the bicuspid valve includes leaflets of different sizes.
23. The apparatus of claim 19, wherein the upper end of the stent is scalloped.
24. The apparatus of claim 19, wherein the stent and the valve are collapsible for insertion into the heart on a catheter.
25. The apparatus of claim 19, wherein the at least one tension member comprises a plurality of tension members, each having a first end connected to one of the leaflets and a second end connected to the valve.
Type: Application
Filed: May 1, 2008
Publication Date: Nov 5, 2009
Applicant: Edwards Lifesciences Corporation (Irvine, CA)
Inventors: Stanton Rowe (Newport Beach, CA), Mark Chau (Aliso Viejo, CA), Son V. Nguyen (Irvine, CA)
Application Number: 12/113,418