WO2008013915A2

WO2008013915A2 - Percutaneous valve prosthesis and system and method for implanting same

Info

Publication number: WO2008013915A2
Application number: PCT/US2007/016855
Authority: WO
Inventors: Arshad Quadri
Original assignee: Arshad Quadri
Priority date: 2006-07-28
Filing date: 2007-07-27
Publication date: 2008-01-31
Also published as: US11141265B2; WO2008013915A9; US20220023039A1; US20160331532A1; WO2008013915A3; US10350065B2; US20190321174A1; US20090306768A1

Abstract

A heart valve prosthesis includes a cylindrical valve cage stent constructed to be implanted percutaneously in the planar axis of a native valve annulus, an elastic and compressible, multi-leaflet valve insertable percutaneously into the body, and an attachment mechanism for attaching the valve to the superior rim of the valve cage stent. The valve can be of a bi-leaflet or a tri-leaflet type and includes a valve frame made from a memory metal and a tissue cover attached to the valve frame. The valve cage stent is self-expanding or balloon expandable, made respectively from memory metal or stainless steel but otherwise structurally the same.

Description

PERCUTANEOUS VALVE PROSTHESIS AND SYSTEM AND METHOD FOR IMPLANTING SAME

CROSS-REFERENCE TO RELATED APPLICATIONS The present patent application is based on, and claims priority from, U.S. provisional

Application No. 60/833,791, filed July 28, 2006, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to heart valve prostheses, preferably to aortic valve prostheses. More specifically, the invention relates to heart valve prostheses that can be implanted percutaneously by means of a catheter from a remote location without opening the chest cavity.

2. Related Art

. Heart valve surgery is used to repair or replace diseased heart valves. Valve surgery is an open-heart procedure conducted under general anesthesia. An incision is made through the patient's sternum (sternotomy), and the patient's heart is stopped while blood flow is rerouted through a heart-lung bypass machine.

Valve replacement may be indicated when there is a narrowing of the native heart valve, commonly referred to as stenosis, or when the native valve leaks or regurgitates. When replacing the valve, the native valve is excised and replaced with either a biologic or a mechanical valve. Mechanical valves require lifelong anticoagulant medication to prevent clot formation around the valve, which can lead to thromboembolic complications and catastrophic valve failure. Biologic tissue valves typically do not require such medication. Tissue valves can be obtained from cadavers (homografts) or can be from pigs (porcine valve) and cows (bovine pericardial valves). Recently equine pericardium has also been used for making valves. These valves are designed to be attached to the patient using a standard surgical technique.

Valve replacement surgery is a highly invasive operation with significant concomitant risk. Risks include bleeding, infection, stroke, heart attack, arrhythmia, renal failure, and adverse reactions to the anesthesia medications, as well as sudden death. Two to five percent of patients die during surgery. Post-surgery, patients temporarily may be confused due to emboli and other factors associated with the heart-lung machine. The first two to three days following surgery are spent in an intensive care unit where heart functions can be closely monitored. The average hospital stay is between one and two weeks, with several more weeks to months required for complete recovery.

In recent years, advancements in minimally invasive, endoaortic, surgery interventional cardiology, and intervention radiology have encouraged some investigators to pursue percutaneous replacement of the aortic heart valve. Percutaneous Valve Technologies ("PVT") of Fort Lee, N.J., has developed a balloon-expandable stent integrated with a bioprosthetic valve, which is the subject of U.S. Patents Nos. 5,411,552, 5,840,081, 6,168,614, and 6,582,462 to Anderson et al. The stent/valve device is deployed across the native diseased valve to permanently hold the valve open, thereby alleviating a need to excise the native valve and to position the bioprosthetic valve in place of the native valve. PVT's device is designed for delivery in a cardiac catheterization laboratory under local anesthesia using fluoroscopic guidance, thereby avoiding general anesthesia and open-heart surgery. The device was first implanted in a patient in April of 2002.

PVT's device suffers from several drawbacks. Deployment of PVT's stent has several drawbacks, including that there is very little control over its deployment. This lack of control can endanger the coronary ostea above the aortic valve and the anterior leaflet of the mitral valve below the aortic valve.

Another drawback of the PVT device is its relatively large cross-sectional delivery profile. This is largely due to fabricating the tri-leafiet pericardial valve inside a robust stainless steel stent. Considering they have to be durable, the materials for the valve and the stent are very bulky, thus increasing the profile of the device. The PVT system's stent/valve combination is mounted onto a delivery balloon, making retrograde delivery through the aorta challenging. An antegrade transseptal approach may therefore be needed, requiring puncture of the septum and routing through the mitral valve, which significantly increases complexity and risk of the procedure. Very few cardiologists are currently trained in performing a transseptal puncture, which is a challenging procedure by itself. Another drawback of the PVT device is, its lack of fixation provision. It in effect uses its radial force to hold the stent in the desired position. For this to work, sufficient dilatation of 1he valve area has to be achieved; but this amount of dilation can cause damage to the arinulus. Also, due to its inability to have an active fixation mechanism, the PVT device cannot be used to treat aortic regurgitation. Another drawback to this system is that it does not address the leakage of blood around the implant, after its implantation.

Other prior art replacement heart valves use self-expanding stents that incorporate a valve. One such device is that disclosed in U.S. Patent No. 7,018,406 to Seguin et al. and assigned to and made by CoreValve SA. In the endovascular aortic valve replacement procedure, accurate placement of aortic valves relative to coronary ostia and the mitral valve is critical. Standard self-expanding systems have very poor accuracy in deployment, however. Often the proximal end of the stent is not released from the delivery system until accurate placement is verified by fluoroscopy and the stent typically jumps once released. It is therefore often impossible to know where the ends of the stent will be with respect to the native valve, the coronary ostia, and the mitral valve. The anchoring mechanism is not actively provided (that is, there is no method of fixation other than the use of radial force and barbs that project into the surrounding tissue and not used as positioning marker (that is, markers seen under fluoroscopy to determine the position of the device). A simple barb as used in the CoreValve device relies mainly on friction for holding the position.

Another drawback of prior art self-expanding replacement heart valve systems is their lack of radial strength. In order for self-expanding systems to be easily delivered through a delivery sheath, the metal needs to flex and bend inside the delivery catheter without being plastically deformed. In arterial stents, this is not a challenge, and there are many commercial arterial stent systems that apply adequate radial force against the vessel wall and yet can collapse to a small enough of a diameter to fit inside a delivery catheter without plastically deforming. However, when the stent has a valve fastened inside it, as is the case in aortic valve replacement, the anchoring of the stent to vessel walls is significantly challenged during diastole. The force required to hold back arterial pressure and prevent blood from going back inside the ventricle during diastole will be directly transferred to the stent/vessel wall interface. Therefore the amount of radial force required to keep the self expanding stent/valve in contact with the vessel wall and prevent it from sliding will be much higher than in stents that do not have valves inside of them. Moreover, a self-expanding stent without sufficient radial force will end up dilating and contracting with each heartbeat, thereby distorting the valve, affecting its function and resulting in dynamic repositioning of the stent during delivery. Stent foreshortening or migration during expansion may lead to improper alignment. Additionally, the stent disclosed in U.S. Patent No. 6,425,916 to Garrison simply crushes the native valve leaflets against the heart wall and does not engage the leaflets in a manner that would provide positive registration of the device relative to the native position of the valve. This increases an immediate risk of blocking the coronary ostia, as well as a longer-term risk of migration of the device post-implantation. Further still, the stent comprises openings or gaps in which the replacement valve is seated post-delivery. Tissue may protrude through these gaps, thereby increasing a risk of improper seating of the valve within the stent.

In view of drawbacks associated with previously known techniques for endovascularly replacing a heart valve, it would be desirable to provide methods and apparatus that overcome those drawbacks.

Sadra et al. (U.S. published application No. 20050137701) describes a mechanism for anchoring a heart valve, the anchoring mechanism having an actuation system operated remotely. This mechanism addresses the fixation issue; however, considering the irregular shape of the aortic annulus there is a real potential for deforming the prosthetic valve annulus; this may require additional balloon angioplasty to give it its final shape, and also make the new valve more prone to fatigue and fracture. Moreover if full expansion of the stent is prone to deformation, the leaflet coaptation of the valve will be jeopardized.

Sadra et al (U.S. published application No. 20050137691) describes a system with two pieces, a valve piece and an anchor piece. The valve piece connects to the anchor piece in such a fashion that it will reduce the effective valve area considerably. Valve area, i.e., the inner diameter of the channel after the valve leaflets open, is of prime importance when considering an aortic valve replacement in a stenotic valve. Garrison's valve is also implanted in the inner portion of the stent, compromising the effective valve outflow area. Sadra et al.'s and Garrison' s valves overlook this very critically important requirement.

The technologies described above and other technologies (for example, those disclosed in U.S. Patent No. 4,908,028 to Colon et al.; U.S. Published Application No. 2003/0014104, U.S. Published Application No. 2003/0109924, U.S. Published Application No. 2005/0251251, U.S. Published Application No. 2005/0203616, and U.S. Patent No. 6,908,481 to Cribier; U.S. Patent No. 5,607,469 to Frey; U.S. Patent No. 6,723,123 to Kazatchkov et al.; Germany Patent No. DE 3,128,704 Al to Kuepper; U.S. Patent No. 3,312,237 to Mon et al.; U.S. Published Application No. 2005/0182483 to Osbourne et al.; U.S. Patent No. 1,306,391 to Romanoff; U.S. Published Application No. 2005/0203618 to Sharkawy et al.; U.S. Published Application No. 2006/0052802 to Sterman et al.; U.S. Patent No. 5,713,952; and U.S. Patent No. 5,876,437 to Vanney et al.) also use various biological, or othei synthetic materials for fabrication of the prosthetic valve. The duration of function and physical deterioration of these new valves have not been addressed. Their changeability has not been addressed, in the percutaneous situation. It is to the solution of these and other problems that the present invention is directed.

SUMMARY OF THE INVENTION

It is accordingly a primary object of the present invention to provide to methods and apparatus for endovascularly replacing a heart valve. In is another object of the present invention to provide methods and apparatus for endovascularly replacing a heart valve with a replacement valve prosthesis using a balloon expandable and/or self expanding valve cage stent upon which a bi-leaflet or tri-leaflet elastic valve is inserted.

It is also a feature of this invention that the valve piece of the implant is removable, and thus exchangeable, in the event of long or medium term failure of the implanted valve.

It is another object of this invention to provide maximal valve area to the out flow tract of the left ventricle, thus minimizing the gradient across the valve, by using a supra annular implant of the valve piece to the valve cage stent.

These and other objects are achieved by a heart valve prosthesis comprising a cylindrical valve cage stent constructed to be implanted percutaneously in the planar axis of a native valve annulus, the valve cage stent having a superior rim; and an elastic and compressible, multi-leaflet valve insertable percutaneously into the body, the valve including a valve frame made from a memory metal and a tissue cover attached to the valve frame; and attachment means for attaching the valve to the superior rim of the valve cage. The valve can. be a bi-leaflet or a tri-leaflet valve. The bi-leaflet valve includes a frame, a tissue cover, a deformable hinge, and means for detachably connecting the valve to the valve cage stent. The frame has two substantially semicircular, expandable, and compressible parts, and the tissue cover is configured to cover the two parts of the frame with the straight sides of the two parts in spaced-apart relation. The tissue cover has a central aperture and the two parts of the frame have respective slots. The deformable binge has oppositely extending arms extending through the slots and a stem received through the aperture. The superior rim of the valve cage stent has a valve mount affixed thereto for receiving a mating part on the hinge, thereby defining the attachment means. The tri-leaflet valve includes a frame, a tissue cover, and means for detachably connecting the valve to the valve cage stent. The frame is cylindrical and has three commissural posts mounted thereon. The tissue cover has three cusps fitted and sewn to the valve frame, the commissural posts being sized to maintain the commissural height of the cusps. The valve cage stent has three commissural pins extending from the superior rim thereof, and the commissural posts of the frame are cannulated to receive the commissural pins of the valve cage stent, thereby defining the attachment means.

Other objects, features and advantages of the present invention will be apparent to those skilled in the art upon a reading of this specification including the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is better understood by reading the following Detailed Description of the Preferred Embodiments with reference to the accompanying drawing figures, in which like reference numerals refer to like elements throughout, and in which:

FIGURE 1 is a diagram of a valve prosthesis in accordance with the present invention.

FIGURE 2A is a diagrammatic plan view of a frame for a bi-leaflet percutaneous heart valve in accordance with the present invention. FIGURE 2B is a diagrammatic plan view of a tissue cover for the frame of FIGURE

2A.

FIGURE 2C is a diagrammatic plan view of an assembled bi-leaflet percutaneous heart valve in accordance with the present invention, incorporating the frame of FIGURE 2A and the tissue cover of FIGURE 2B. FIGURE 2D is a diagrammatic side elevational view of the bi-leaflet percutaneous heart valve of FIGURE 2C in the open position.

FIGURE 2E is a diagrammatic side elevational view of the bi-leaflet percutaneous heart valve of FIGURE 2C in the closed position.

FIGURE 2F is a top perspective view of an assembled bi-leaflet percutaneous heart valve in accordance with the present invention, in the closed position.

FIGURES 2G and 2H are top and side perspective views of the bi-leaflet percutaneous heart valve of FIGURE 2F in the open position.

FIGURES 21 and 2 J are side perspective views of the valve cage stent for use with the bi-leaflet percutaneous heart valve of FIGURE 2F. FIGURE 2K is a partial perspective view of the bi-leaflet percutaneous heart valve of FIGURE 2F mounted on the valve cage stent of FIGURE 21, with the valve in the closed position.

FIGURE 2L is a partial perspective view of the bi-leaflet percutaneous heart valve of FIGURE 2F mounted on the valve cage stent of FIGURE 21, with the valve in the open position.

FIGURE 3A is a diagrammatic perspective view of a frame for a tri-leaflet percutaneous heart valve in accordance with the present invention.

FIGURE 3B is a perspective view of a tissue cover for the frame of FIGURE 3 A. FIGURE 3C is a perspective view of an assembled tri-leaflet percutaneous heart valve in accordance with the present invention, incorporating the frame of FIGURE 3A and the tissue cover of FIGURE 3B.

FIGURE 3D is a side perspective view of the valve cage stent for use with the tri- leaflet percutaneous heart valve of FIGURE 3C. FIGURES 3E and 3F are top perspective views of the valve cage stent for use with the tri-leaflet percutaneous heart valve of FIGURE 3C.

FIGURE 3 G is a diagrammatic view of a portion the valve cage stent for use with the tri-leaflet percutaneous heart valve of FIGURE 3C₅ which as been opened up and flattened for purposes of illustration. FIGURE 3H is a partially cut-away perspective view of the tri-leaflet percutaneous heart valve of FIGURE 3C mounted on the valve cage stent of FIGURE 3D, in the undeployed condition.

FIGURE 31 is a partially cut-away perspective view of the tri-leaflet percutaneous heart valve of FIGURE 3C mounted on the valve cage stent of FIGURE 3D, in the deployed condition.

FIGURES 4A-4G show the sequence of steps in implantation of the bi-leaflet percutaneous heart valve prosthesis of FIGURE 2C in an aorta, in which the valve is attached to the valve cage stent outside the delivery catheter.

FIGURES 5A-5I are diagrammatic representations of the sequence of steps in implantation of the bi-leaflet percutaneous heart valve of FIGURE 2C, the aorta being omitted from ail of FIGURES 5A-5I and the valve cage being omitted from FIGURES 5A-5F for clarity. FIGURES 6A-6J show the sequence of steps in Implantation of the tri-leaflet percutaneous heart valve of FIGURE 3C in an aorta, in which the valve is attached to the valve cage stent outside the delivery catheter.

FIGURES 7 A and 7B are exploded and assembled views, respectively, of the delivery system apparatus used in implantation of the bi-leaflet and tri-leaflet valves in accordance with the present invention.

FIGURE 7C is an end view of the flexible sheath of the delivery system apparatus of FIGURES 7A and 7B.

FIGURE 8 is a side view of a valve cage stent mounted on a balloon catheter. FIGURES 9A-9T show the sequence of steps in implantation of the tri-leaflet percutaneous heart valve of FIGURE 3C in an aorta, in which the valve is attached to the valve cage stent within the delivery catheter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. The present invention relates to heart valve prostheses that can be implanted percutaneously by means of a catheter from a remote location without opening the chest cavity. As shown in FIGURE I₃ the valve prosthesis 10 comprises two parts, (1) a valve cage stent 20 constructed to be implanted in the planar axis of the native valve annulus, (2) an elastic and compressible valve 30, and (3) an attachment mechanism for attaching the valve 30 to the superior rim of the above mentioned valve cage stent 20. In accordance with the present invention, two types 110 and 210 of heart valve prosthesis 10 are contemplated, one type 110 incorporating an elastic and compressible bi-leaflet hinged valve 130 (shown in FIGURES 2A-2E) and the other type 210 incorporating an elastic and compressible tri-leaflet biologic valve 230 (shown in FIGURES 3A-3C). A system and method for implanting the valves (shown in FIGURES 4A-4G, 5A-5I, and 6A-6J) is also encompassed by the invention. Referring now to FIGURES 2A-2H, the bi-leaflet tissue valve 130 comprises a two- part (that is, a two-leaflet) frame 132 made from a memory metal wire or strip and a tissue cover 133. As best shown in FIGURE 2A, each part 132a and 132b of the frame 132 is substantially semicircular. Portions of each part 132a and 132b of the frame 132 (for example, the straight side and the center portion of the curved side) are configured (for example, by having a sinusoidal configuration, shown by broken lines in FIGURES 2A and 2C) so that each part 132a and 132b of the frame 132, as well as the frame 132 as a whole, is expandable and compressible, while the remaining portions of the frame 132 are not expandable and compressible.

Each part 132a and 132b of the frame 132 includes a slot 134 for receiving a hinge 135 having a shape when deployed that is similar to a lower-case "t", as shown in FIGURES 2D and 2E. having two arms 135a and 135b and a stem 135c. The slot 134 is formed unitarily with the frame 132. The "t"-shaped hinge 135 is stamped out of memory metal (for example, nitinol) sheeting so that it is deformable. The arms 135 and 135b of the hinge 135 have projections 135d at their ends, which function as stops for the leaflets. The stem 135c of the hinge 135 has a snap-on or screw-in mechanism 141 for attachment to a valve mount 142 (shown in FIGURES 2I-2L), as described below.

The tissue cover 133 (shown in FIGURE 2B) is made, for example, of equine or bovine pericardium, or various synthetic materials, for example, or medical grade silicone, fabric, or other compressible, materials, and is configured to cover the two parts 132a and 132b of the frame 132 with their straight sides in spaced apart relation, with a central aperture 133a in the center for receiving the stem of the "t"-shaped hinge 135 and two side apertures 133b in alignment with the slots 134 for receiving the arms 135a and 135b of the hinge 135. The tissue cover 133 is sewn to each part 132a and 132b of the frame 132, as shown in FIGURES 2C and 2F-2H, and thus connects the two parts 132a and 132b of the frame 132 in spaced-apart relation.

As discussed in greater detail below, in use, the bi-leaflet valve 130 is detachably connected to a valve mount 142 (shown in FIGURES 21 and 2J) via the "t"-shaped hinge 135, as shown in FIGURES 2K-2N, 4D-4G, and 5G-5I. The valve mount 142 is also made from a memory metal so that it is collapsible. More specifically, the valve mount 142 has arms 142a and 142b on either side of a receptacle 142c, which are folded up vertically when the valve cage stent 120 is in its compressed (undeployed) condition, the ends of the arms 142a and 142b being affixed to the valve cage stent 120. The detachable and collapsible bi-leafiet construction of the valve 130 enables the valve 130 in conjunction with its entire delivery system to be sized down so that it can be inserted percutaneously using a catheter, as described below.

Referring now to FIGURES 3A-3C, the tri-leafiet tissue valve 230 comprises an expandable and compressible valve frame 232 (shown in FIGURE 3A) made from a memory metal wire or strip and a tissue cover 233 (shown in FIGURE 3B and 3C). The tissue cover 233 is made from the individual cusps of a porcine aortic valve sewn to appropriate fabric. Three identical cusps are selected. Two or more pigs are used to get ideal sized aortic cusps. The muscle bar cusp is preferably not used; and all of the sinus and surrounding tissue is discarded. The commissural height is maintained at all cost. The tissue cover 233 (that is, the cusps sewn to the fabric) is fitted and sewn to the valve frame 232. The valve frame 232 has three cannulated commissural posts 240a, 240b, and 240c mounted thereon, and the tissue cover 233 is sewn to the commissural posts 240a, 240b, and 240c to complete the tri-leaflet valve 230 (FIGURE 3C). As shown in FIGURES 3A-3C, the tri-leaflet valve 230 is mounted on commissural pins 240aa, 240bb, and 240cc provided on a valve cage stent 220 of the type disclosed in provisional application No. 60/735,221, Attorney Docket P70721US0, which is incorporated herein by reference in its entirety. More specifically, the commissural posts 240a, 240b, and 240c of the valve frame 232 are cannulated to receive the commissural pins 240aa, 240bb, and 240cc, respectively, of the valve cage stent 220, thereby connecting the valve frame 232 (and thus the valve 230) to the valve cage stent 220. As described below, the heart valve prosthesis 210 incorporating the tri-leaflet valve 230 is delivered using a catheter.

As shown in FIGURE 3G, the valve cage stent 220 for use with the tri-leaflet valve 230 has three different zones 221, 222, and 223 along its longitudinal axis, the different zones having different geometric configurations so as to perform different functions. The first, or center, zone 221 functions as the stent connector, which is identical to the stent disclosed in Int'al Patent Application No. PCT/US2006/043526, filed November 9, 2006 (which is based on U.S. Provisional Application No. 60/735,221), and which connects to the native valve annulus. The second and third zones 222 and 223, at either end of the center zone 221, function respectively as the superior valve rim carrying the commissural pins in the tri-leaflet valve prosthesis 210 or the valve mount in the bi-leaflet valve prosthesis 110, and the inferior valve skirt. The valve skirt 223 provides additional support, as well as a fabric/tissue attachment area to minimize leaking.

The present invention also encompasses a system and method for implanting the above-described percutaneous valve prostheses 10 in the body. In a first embodiment, the system comprises a valve cage stent 20 for implantation in the body by the use of a first catheter of a delivery system 500 (shown in FIGURES 8A and 8B, and as described in greater detail hereinafter) to provide a stable, fixed, and sturdy frame within which an elastic, compressible valve 30 can be inserted and secured by a second catheter (not shown), and the valve 30 is attached to the valve cage stent 20 after they are discharged from their respective catheters. Performing the procedure in two parts at the same session downsizes the devices considerably, so that the procedure can be performed percutaneously. In a second embodiment, the system comprises a valve cage stent 20 and an elastic, compressible valve 30 which are inserted using the same catheter, and the valve 30 is attached to the valve cage stent 20 within the catheter, as shown in FIGURES 9A-9T.

The valve cage stent 20 is a self-expanding or balloon expandable cylindrical valve cage stent 20, made from memory metal, or stainless steel respectively. The self-expanding valve cage stent and the balloon expandable valve cage stent are structurally the same (that is, they differ only in the material from which they are made). The valve cage stent 20 is fabricated from metal tubing (memory metal or stainless steel), so that it is cylindrical in shape, with the stent pattern being cut into the tubing by laser.

The expansion of the valve cage stent 20 produces maximal foreshortening of the ovals in the mid portion of the stent and thus provides active fixation of the stent to the annulus of the valve being replaced. The valve cage stent 20 has a fabric covering on its interior and parts of its exterior surfaces so in its expanded state it forms a complete seal and does not allow any leakage of blood.

For delivery, the valve cage stent 20 is mounted on a balloon 600 (FIGURE 8), or in a restraining sheath if self-expandable. The delivery system apparatus 500 is shown in FIGURES 7A-7C. The delivery system apparatus 500 comprises a flexible outer sheath 510, in which the valve cage stent 20 is inserted with a first set of guide wires 520 attached thereto, followed by a slotted nosecone 530 having another set of guide wires 540 attached thereto.

The valve cage stent 20 has provisions for the attachment of the prosthetic valve, depending on the type of prosthetic valve contemplated to be used. For example, in the case of a bi-leaflet valve, the valve is attached to the valve cage stent 120 via a valve mount affixed to the valve cage stent 120, as shown in FIGURES 4D-4G and 5G-5L In the case of a tri-leaflet valve, the valve is attached to the valve cage stent 220 via engagement of the valve commissural posts 240a, 240b, and 240c with the commissural pins 240aa, 240bb, and 240cc of the valve cage stent 220, as shown in FIGURES 6H-6J.

The delivery system employs a two stage procedure, both stages of which can be performed at the same session, only minutes apart. The first stage is insertion of the valve cage stent 20. In the case of a bi-leaflet valve, as shown in FIGURE 4 A, the valve cage stent 120 has a valve mount connected thereto and a guide wire connected to the valve mount. In the case of a tri-leaflet valve, as shown in FIGURES6 A-6G and as described above, the valve cage stent 220 has three commissural pins 240aa, 240bb, and 240cc provided thereon and guide wires connected thereto.

The second stage is insertion of the elastic and compressible valve, which is restrained in another catheter (not shown) for delivery into the valve cage stent 20. As shown in

FIGURES 4A-4D, 5A-5F, and 6A-6H, in the second stage, the valve is placed over the guide wire (in the case of a bi-Ieaflet valve) or guide wires (in the case of the tri-leaflet valve) connected to the valve cage stent 20 in order to ensure proper positioning of the valve relative to the stent. Once the valve is seated, the guide wire or wires are withdrawn (FIGURES 4D- 4G₅ 5G-5I, and 61-6 J).

Because the bi-leaflet valve is detachable from the valve mount, it can be replaced when necessary. The valve mount has a snap-on or screw-in mechanism for attachment of the

"t"-shaped hinge 135 thereto, as well as the above-described guide wire attached to it for placement of the valve. The use of a valve cage 20 allows for fabrication of a tri-leaflet tissue valve.

In addition, the connection of valve 30 to the valve cage stent 20 provides the best effective flow dynamics, the flexibility of the whole system 500 is greatly increased, and the profile of the whole system 500 is reduced so that it can be inserted through a small opening in the access vessel. Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.

Claims

I CLAIM:

1. A heart valve prosthesis comprising: an expandable and compressible, cylindrical valve cage stent constructed to be implanted endovascularly in the planar axis of a native valve annulus, the valve cage stent having a superior rim; an elastic and compressible, multi-leaflet valve insertable endovascularly into the body, the valve including an expandable and compressible valve frame and a tissue cover attached to the valve frame; and attachment means for attaching the valve to the superior rim of the valve cage.

2. The heart valve prosthesis of claim 1, wherein the valve frame is made from a memory metal.

3. The heart valve prosthesis of claim 1 , wherein: the valve cage stent has a fabric covering on the interior surfaces thereof and on parts of the exterior surfaces thereof to provide a complete seal and prevent leakage of blood when the valve cage stent is expanded; and the valve cage stent has first, second, and third zones along its longitudinal axis, the first zone being between the second and third zones, the first zone being configured to connect the valve cage stent to the native valve annulus, the second zone being configured as the superior valve rim, and the third zone being configured as an inferior valve skirt for providing additional support and as an attachment area for the fabric covering and surrounding tissue to minimize leaking.

4. The heart valve prosthesis of claim 1, wherein the valve is a bi-leaflet valve, the frame has two substantially semicircular, expandable, and compressible parts, and the tissue cover is configured to cover the two parts of the frame with the straight sides of the two parts in spaced-apart relation.

5. The heart valve prosthesis of claim 4, wherein the tissue cover has a central aperture and the two parts of the frame have respective slots, and wherein the heart valve prosthesis further comprises a deformable hinge having oppositely extending arms extending through the slots and a stem received through the aperture, and wherein the attachment means comprises a valve mount affixed to the superior rim of the valve cage stent and a mating part on the hinge receivable in the valve mount.

6. The heart valve prosthesis of claim 5, wherein the oppositely extending arms of the hinge have stops at the ends thereof for limiting movement of the leaflets.

7. The heart valve prosthesis of claim 5, wherein the mating part on the hinge is removable from the valve mount, whereby the valve is replaceable.

8. The heart valve prosthesis of claim 1, wherein the valve is a tri-leaflet valve, the frame is cylindrical and has three commissural posts mounted thereon, the tissue cover has three cusps fitted and sewn to the valve frames, the commissural posts being sized to maintain the commissural height of the cusps.

9. The heart valve prosthesis of claim 8, wherein the valve cage stent has three commissural pins extending from the superior rim thereof, wherein the commissural posts of the frame are cannulated to receive the commissural pins of the valve cage stent, and wherein the commissural pins and the commissural posts define the attachment means.

10. The heart valve prosthesis of claim 8, wherein the tissue cover comprises fabric and three substantially identical aortic cusps affixed to the fabric.

11. A method for implanting the percutaneous valve prostheses of claim 1 in a body, comprising the steps of: endovascularly inserting the valve cage stent in the planar axis of a native valve annulus; and endovascularly attaching the valve to the superior rim of the valve cage stent so that the valve is in a supra annular position.

12. The method of claim 11, wherein the valve cage stent and the valve are inserted using respective catheters, and wherein the valve is attached to the valve cage stent after they are discharged from their respective catheters.

13. The method of claim 11, wherein the valve cage stent and the valve are inserted using the same catheter, and the valve is attached to the valve cage stent within the catheter.