FIELD OF THE INVENTION

The present invention relates to methods and systems used to deliver a prosthetic valve to a heart. More specifically, the present invention relates to methods and apparatus for surgically replacing a heart valve without opening the chest cavity and with or without placing the patient on bypass, the latter being termed “off-pump.”

BACKGROUND OF THE INVENTION

Heart 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, such as when the leaflets are calcified. When replacing the valve, the native valve may be excised and replaced with either a biologic or a mechanical valve. Mechanical valves require lifelong anticoagulant medication to prevent blood clot formation, and clicking of the valve often may be heard through the chest. Biologic tissue valves typically do not require such medication. Tissue valves may be obtained from cadavers or may be porcine or bovine, and are commonly attached to synthetic rings that are secured to the patient's heart valve annulus.

Conventional heart 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 “cardiopulmonary” bypass machine. Valve replacement surgery is a highly invasive operation with significant concomitant risks including bleeding, infection, stroke, heart attack, arrhythmia, renal failure, adverse reactions to the anesthesia medications, as well as sudden death. Fully 2-5% 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 2-3 days following surgery are spent in an intensive care unit where heart functions can be closely monitored. The average hospital stay is between 1 to 2 weeks, with several more weeks to months required for complete recovery.

In recent years, advancements in “minimally-invasive” surgery and interventional cardiology have encouraged some investigators to pursue percutaneous replacement of the aortic heart valve. Percutaneous Valve Technologies (“PVT”), formerly of Fort Lee, N.J. and now part of Edwards Lifesciences of Irvine, Calif., has developed a balloon-expandable stent integrated with a bioprosthetic valve. 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. 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.

Other prior art minimally-invasive heart valves use self-expanding stents as anchors. In the percutaneous/endovascular aortic valve replacement procedure, accurate placement of the prosthetic valve relative to the coronary ostia is critical. Though the proximal end of the stent is not released from the delivery system until accurate placement is verified by fluoroscopy, the self-expanding stent may still jump once released. It is therefore often difficult to know where the ends of the stent will be with respect to the native valve and surrounding structures.

U.S. Patent Publication No. 2002/0151970 to Garrison et al. describes a two-piece device for replacement of the aortic valve that is adapted for delivery through a patient's aorta. A stent is endovascularly placed across the native valve, then a replacement valve is positioned within the lumen of the stent and connected thereto. By separating the stent and the valve during delivery, a so-called “two-stage” approach, the profile of the delivery system can be reduced. Both the stent and a frame of the replacement valve may be balloon- or self-expandable.

Some researchers propose implanting prosthetic heart valves at the aortic annulus through a ventricular approach. For instance, Christoph H. Huber of the Brigham and Women's Hospital of Harvard Medical School, and others, have proposed a procedure in which a self-expanding valve stent is implanted at the aortic position using a direct-access transapical approach. (E.g., Huber, et al. Direct-access valve replacement a novel approach for off-pump valve implantation using valved stents. J Am Coll Cardiol 2005; 46:366-70). The clinical studies by Huber, et al. recommend use of the procedure only for animals with normal, noncalcified leaflets. More recently, Bergheim in U.S. Patent Publication No. 2005/0240200 discloses another transapical approach in which either a balloon- or self-expanding valve may be implanted, and also proposes removing or decalcifying stenotic valves.

In view of drawbacks associated with previously known techniques for replacing a heart valve without open-heart surgery or cardiopulmonary bypass, i.e., minimally-invasive procedures, improved methods and apparatuses that are more robust and less invasive are needed.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a heart valve delivery system for delivery of a prosthetic (i.e., replacement) heart valve to a native valve site without an open chest procedure. The delivery system includes a valve delivery catheter having a steerable section to facilitate positioning of the valve.

In accordance with one aspect, the present invention provides an off-pump, minimally-invasive surgical method of implanting a prosthetic heart valve to an aortic valve annulus of a patient while the patient's heart remains beating. The method includes providing a balloon-expandable prosthetic heart valve mounted over a balloon on a distal end of a balloon catheter. The physician creates a puncture through the ventricle wall at or near the apex of the left ventricle of the patient and inserts an introducer sheath through the puncture. A balloon catheter passes through the introducer sheath into the left ventricle. The distal end of the balloon advances so that the prosthetic heart valve is positioned within the aortic annulus. Finally, the balloon inflates to expand the prosthetic heart valve at the aortic annulus.

The method may also include placing a first line of purse-string sutures generally in a first circle in one direction defining a perimeter at or near the apex of the left ventricle of the patient, and then placing a second line of purse-string sutures generally in a circle concentric to the first circle but in an opposite direction. The puncture is created within the perimeter, and after the introducer sheath is inserted through the puncture, the purse-string sutures are cinched to create a seal therearound.

Desirably, the balloon catheter incorporates a steering mechanism, and the method further includes steering the balloon catheter within the left ventricle to facilitate positioning the prosthetic heart valve within the aortic annulus. The balloon catheter may also include a deflecting segment located just proximal to the balloon which bends so as to angle the balloon and prosthetic heart valve mounted thereon. The balloon catheter may also have a pusher with a distal sleeve mounted over the deflecting segment and engaging a proximal end of the balloon. The method therefore includes using the pusher and sleeve to advance the balloon and prosthetic heart valve mounted thereon, and proximally displacing the pusher and sleeve with respect to the deflecting segment prior to inflating the balloon. Desirably, the pusher and sleeve are proximally displaced before the deflecting segment bends.

The exemplary method may further include leaving the native aortic valve leaflets in place such that inflating the balloon expands the prosthetic heart valve into contact therewith. Furthermore, a pre-dilation balloon catheter may be inserted prior to the introducer sheath and a balloon thereon inflated to pre-dilate the aortic annulus. Alternatively, the method may include expanding the prosthetic heart valve into contact with a prosthetic heart valve that was previously implanted at the aortic annulus

Another off-pump, minimally-invasive surgical method of delivering a prosthetic heart valve to an aortic valve annulus of a patient while the patient's heart remains beating includes providing an expandable prosthetic heart valve in an expanded state and a delivery catheter having a distal end. The heart valve is crimped to a contracted state over the delivery catheter distal end. An intercostal access opening is created to expose the left ventricular apex of the patient, and a puncture formed at or near the apex of the left ventricle. An introducer sheath inserts through the puncture, and the delivery catheter passes through the introducer sheath and into the left ventricle. The distal end of the delivery catheter is advanced and steered so that the prosthetic heart valve is properly positioned and oriented within the aortic annulus. Finally, the prosthetic heart valve expands at the aortic annulus into contact therewith.

The delivery catheter desirably includes a balloon on its distal end, and the prosthetic heart valve includes a balloon-expandable stent, wherein the step of expanding includes injecting fluid into the balloon to expand the prosthetic heart valve outward into contact with the aortic annulus. The native aortic valve leaflets may be left in place such that inflating the balloon expands the prosthetic heart valve into contact therewith. Preferably, prior to inserting the introducer sheath, a pre-dilation balloon catheter having a balloon on a distal end is inserted through the puncture and inflated to pre-dilate the aortic annulus.

The present invention further encompasses a minimally-invasive prosthetic heart valve delivery system, including an introducer sheath having a lumen therethrough of no greater than 24 French and a balloon catheter having a balloon on a distal end, the balloon catheter further including a steering mechanism for deflecting the distal end. The system includes a balloon-expandable prosthetic heart valve crimped over the balloon, wherein the outer dimension of the balloon catheter with the prosthetic heart valve crimped thereon is small enough to pass through the introducer sheath lumen.

Desirably, the steering mechanism includes a deflecting segment on the balloon catheter located just proximal to the balloon. A deflection wire may be attached to a distal end of the deflecting segment and extend through the balloon catheter to a proximal deflection handle. The system preferably has a pusher with a distal sleeve sized to encompass the deflecting segment and a proximal end of the balloon, the pusher being longitudinally movable with respect to the deflecting segment.

In one embodiment, the balloon catheter further includes inner and outer balloon inflation tubes attached to opposite ends of the balloon and arrange to concentrically slide with respect one another to alternately elongate and shorten the balloon. An inner tube handle displaces the inner balloon inflation tube. A balloon inflation connector through which the inner balloon inflation tube passes attaches to a proximal end of the outer balloon inflation tube. A side port opens to a space defined within the balloon inflation connector, the side port facilitating introduction of an inflation fluid into the space and into a tubular space between the inner and outer balloon inflation tubes for inflating the balloon. A deflection handle through which the outer balloon inflation tube passes may be attached just distal to the balloon inflation connector. The outer balloon inflation tube includes a first lumen for passage of the inner balloon inflation tube, and a second lumen. A deflection wire connects to an actuator on the deflection handle and passes through the second lumen of the outer balloon inflation tube to a distal end of the balloon catheter.

The system is desirably relatively short, such that the balloon catheter has a working length sized to fit into the introducer of no more than about 24 inches (61 cm). At the same time, the introducer preferably has a total length of no more than about 13 inches (33 cm).

A further understanding of the nature and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.

