BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to medical methods, devices, and systems. In particular, the present invention relates to methods, devices, and systems for the endovascular or minimally invasive surgical repair of the atrioventricular valves of the heart, particularly the mitral valve.

[0004] Mitral valve regurgitation is characterized by retrograde flow from the left ventricle of a heart through an incompetent mitral valve into the left atrium. During a normal cycle of heart contraction (systole), the mitral valve acts as a check valve to prevent flow of oxygenated blood back into the left atrium. In this way, the oxygenated blood is pumped into the aorta through the aortic valve. Regurgitation of the valve can significantly decrease the pumping efficiency of the heart, placing the patient at risk of severe, progressive heart failure.

[0005] Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, or the papillary muscles themselves may be damaged or otherwise dysfunctional. Commonly, the valve annulus may be damaged, dilated, or weakened limiting the ability of the mitral valve to close adequately against the high pressures of the left ventricle.

[0006] The most common treatments for mitral valve regurgitation rely on valve replacement or strengthening of the valve annulus by implanting a mechanical support ring or other structure. The latter is generally referred to as valve annuloplasty. A recent technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the “bow-tie” or “edge-to-edge” technique. While all these techniques can be very effective, they usually rely on open heart surgery where the patient's chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated morbidity.

[0007] For these reasons, it would be desirable to provide alternative and additional methods, devices, and systems for performing the repair of mitral and other cardiac valves, particularly the tricuspid valve which is the other atrioventricular valve. Such methods, devices, and systems should preferably not require open chest access and be capable of being performed endovascularly, i.e., using devices which are advanced to the heart from a point in the patient's vasculature remote from the heart. Still more preferably, the methods, devices, and systems should not require that the heart be bypassed, although the methods, devices, and systems should be useful with patients who are bypassed and/or whose heart may be temporarily stopped by drugs or other techniques. At least some of these objectives will be met by the inventions described hereinbelow.

[0008] 2. Description of the Background Art

[0009] Minimally invasive and percutaneous techniques for coapting and modifying mitral valve leaflets to treat mitral valve regurgitation are described in WO 98/35638; WO 99/00059; WO 99/01377; and WO 00/03759.

[0010] Dec and Fuster (1994) N. Engl. J. Med. 331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg. 112:238-247 are review articles discussing the nature of and treatments for dilated cardiomyopathy.

[0011] Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci et al. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al. (1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgical procedures for performing “edge-to-edge” or “bow-tie” mitral valve repair where edges of the opposed valve leaflets are sutured together to lessen regurgitation.

[0012] Mitral valve annuloplasty is described in the following publications. Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996) Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J. 129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmental annuloplasty for mitral valve repair is described in Ricchi et al. (1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty is described in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268; Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989) Ann. Thorac. Surg. 48:670676.

[0013] Percutaneous transluminal cardiac repair procedures are described in Park et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am. Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc. Diagn. 23:257-262.

[0014] Endovascular cardiac valve replacement is described in U.S. Pat. Nos. 5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854. See also U.S. Pat. No. 3,671,979 which describes a catheter for temporary placement of an artificial heart valve.

[0015] Other percutaneous and endovascular cardiac repair procedures are described in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and WO 91/01689.

[0016] Thoracoscopic and other minimally invasive heart valve repair and replacement procedures are described in U.S. Pat. Nos. 5,855,614; 5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.

BRIEF SUMMARY OF THE INVENTION

[0017] The present invention provides methods, devices, and systems for the endovascular repair of cardiac valves, particularly the atrioventricular valves which inhibit back flow of blood from a heart ventricle during contraction (systole), most particularly the mitral valve between the left atrium and the left ventricle. By “endovascular,” it is meant that the procedure(s) of the present invention are performed with interventional tools and supporting catheters and other equipment introduced to the heart chambers from the patient's arterial or venous vasculature remote from the heart. The interventional tools and other equipment may be introduced percutaneously, i.e., through an access sheath, or may be introduced via a surgical cut down, and then advanced from the remote access site through the vasculature until they reach the heart. Thus, the procedures of the present invention will generally not require penetrations made directly through the exterior heart muscle, i.e., myocardium, although there may be some instances where penetrations will be made interior to the heart, e.g., through the interatrial septum to provide for a desired access route. While the procedures of the present invention will usually be percutaneous and intravascular, many of the tools will find use in minimally invasive and open surgical procedures as well. In particular, the tools for capturing the valve leaflets prior to attachment can find use in virtually any type of procedure for modifying cardiac valve function.

[0018] The atrioventricular valves are located at the junctions of the atria and their respective ventricles. The atrioventricular valve between the right atrium and the right ventricle has three valve leaflets (cusps) and is referred to as the tricuspid or right atrioventricular valve. The atrioventricular valve between the left atrium and the left ventricle is a bicuspid valve having only two leaflets (cusps) and is generally referred to as the mitral valve. In both cases, the valve leaflets are connected to the base of the atrial chamber in a region referred to as the valve annulus, and the valve leaflets extend generally downwardly from the annulus into the associated ventricle. In this way, the valve leaflets open during diastole when the heart atria fill with blood, allowing the blood to pass into the ventricle. During systole, however, the valve leaflets are pushed together and closed to prevent back flow of blood into the atria. The lower ends of the valve leaflets are connected through tendon-like tissue structures called the chordae, which in turn are connected at their lower ends to the papillary muscles. Interventions according to the present invention may be directed at any one of the leaflets, chordae, annulus, or papillary muscles, or combinations thereof. It will be the general purpose of such interventions to modify the manner in which the valve leaflets coapt or close during systole so that back flow or regurgitation is minimized or prevented. While the procedures of the present invention will be most useful with the atrioventricular valves, at least some of the tools described hereinafter may be useful in the repair of other cardiac valves, particularly the aortic valve.

[0019] The methods of the present invention will usually comprise accessing a patient's vasculature at a location remote from the heart, advancing an interventional tool through the vasculature to a ventricle and/or atrium, and engaging the tool against a tissue structure which forms or supports the atrioventricular valve. By engaging the tool against the tissue structure, the tissue structure is modified in a manner that reduces valve leakage or regurgitation during ventricular systole. The tissue structure may be any of one or more of the group consisting of the valve leaflets, chordae, the valve annulus, and the papillary muscles. Optionally, the interventional tool will be oriented relative to the atrioventricular valve and/or tissue structure prior to engaging the tool against the tissue structure. The interventional tool may be self-orienting (e.g., pre-shaped) or may include active mechanisms to steer, adjust, or otherwise position the tool. Alternatively, orientation of the interventional tool may be accomplished in whole or in part using a separate guide catheter, where the guide catheter may be pre-shaped and/or include active steering or other positioning means. In all cases, it will usually be desirable to confirm the position prior to engaging the valve leaflets or other tissue structures. Such orienting step may comprise positioning the tool relative to a line of coaptation in the atrioventricular valve, e.g., engaging positioning elements in the valve commissures.

[0020] In a first aspect of the method of the present invention, the tissue structure comprises the valve leaflets and the engaging step comprises attaching one or more opposed points on or along the valve leaflets together. In the case of the bicuspid mitral valve, the attachment points may be located at or near the center of each leaflet, creating a generally symmetric structure with two openings, i.e., between the attachment point(s) and each of the two commissures. Alternatively, the attachment points may be close to each of the commissures. Both will effectively reduce the area in which the valve can open. In the case of the tricuspid valve, any two of the three leaflets can be partially or totally closed together or all three may be partially closed together.

[0021] In both cases, the attachment of the valve leaflets may be performed in a variety of ways, including suturing, clipping, stapling, riveting, gluing, fusing, or the like. While each of these approaches may differ significantly in the protocols and devices used for performing them, the end result will be the same, i.e., improved ability of the atrioventricular valve to close against the elevated pressures within the ventricle during systole. In order to improve apposition of the valve leaflets, it may be preferred to attach the leaflets at a point spaced inwardly from the free edge of the leaflet. Usually, the attachment point within the valve leaflet will be located from 1 mm to 4 mm inward from the free edge.

[0022] It will frequently be desirable to stabilize the interventional tool relative to the valve leaflets and other heart tissue structures at least some points during the interventional procedure. In a broad sense, such stabilization is intended primarily to couple motion of the interventional tool to the motion of the heart so that the tool may then engage the valve leaflets or other target tissue structures with minimum differential motion. The stabilization may be achieved either through the interventional tool or through a guide catheter or other platform which is used to deliver the interventional tool. In both cases, stabilization will usually be achieved by engaging a tissue structure of the heart, such as the interatrial septum, the atrial wall, the valve annulus, the valve chordae, the papillary muscles, or the like. For antegrade approaches, immobilization of either the guide catheter, the interventional tool, or both relative to the valve annulus or valve commissures will be particularly effective. For retrograde approaches, immobilization against the papillary muscles, the chordae, or the valve leaflets themselves may be particularly effective. Stabilization should be distinguished from valve capture which is usually performed after the interventional tool and/or guide catheter have been stabilized within the heart. Thus, the methods of the present invention may comprise up to four separate steps or phases prior to valve affixation. First, the interventional tool and/or guide catheter may be positioned, either actively or passively. Second, the interventional tool and/or guide catheter may be stabilized within the heart. Next, the interventional tool may be used to capture the valve leaflets. Then, prior to affixation, the valve leaflets may be positioned and, if necessary, repositioned in order to determine that a particular coaptation and affixation are capable of inhibiting the valve regurgitation. Finally, once adequate regurgitation inhibition has been confirmed, the valve leaflets may be affixed in any of the manners described below.

[0023] In a particular approach, the interventional tool may be stabilized by mechanically fixing the shape of the tool after the tool has been advanced to a position proximate the atrioventricular valve. For example, the interventional tool can comprise a plurality of linked elements which can be locked into place, e.g., a “goose-neck” device. Such mechanically lockable devices may be used by themselves or in conjunction with any of the other stabilization devices described herein.

[0024] When attaching portions of the valve leaflets together, it will frequently be desirable to temporarily capture the valve leaflets before implementing the final attachment step. For example, the leaflets can be captured using forceps or other graspers introduced as part of or separately from the interventional tool. After capturing the valve leaflets, flow through the valve can be observed by conventional cardiac imaging techniques, such as trans-esophegeal echocardiography (TEE), intracardiac echocardiography (ICE) or other ultrasonic imaging technique, fluoroscopy, angioscopy, catheter based magnetic resonance imaging (MRI), computed tomography (CT) and the like. By thus observing the flow through the valves, and more importantly whether or not back flow or regurgitation continues or has been sufficiently inhibited, the desired attachment configuration for the leaflets can be determined. If continued regurgitation is observed, the valve leaflets may be repositioned and the presence or absence of regurgitation again determined. Such repositioning steps may be continued until a position is identified in which the regurgitation is sufficiently inhibited. Additionally, other considerations, such as position of the attachment within the leaflet, stress placed on the leaflet, and other factors can be visualized before deciding on the final attachment point(s). In a preferred example, the valve leaflets may be coapted by a grasping instrument which also has a fixation mechanism, such as stapling, suturing, clipping or riveting as previously described, so that once a desirable attachment configuration is temporarily achieved, the final attachment can be made using the same instrument. Grasping of the valve leaflets can be accomplished using articulated graspers, vacuum-assisted graspers, grasping pins, or other temporary attachment modes as described in more detail below. After the leaflets are in the desired configuration, they may be permanently secured together by any of the techniques described above.

[0025] In a second aspect of the method of the present invention, the tissue structure comprises the chordae and the engaging step comprises linking opposed chordae together, i.e., chordae attached to different valve leaflets. Usually, the chordae will be partially gathered or coupled together using a suture or other loop structure. In some instances it may be desirable to closely tie the chordae together at one or more locations.

[0026] In a third aspect of the method of the present invention, the tissue structure comprises the chordae and the engaging step comprises applying energy to shorten the chordae. Particular forms of heat energy, most particularly radiofrequency energy, have been found to be able to modify and shrink collagen so that supporting chordae may be tightened. By applying energy to shorten one or more of the chordae attaching either or both (or all three in the case of the tricuspid valve) valve leaflets, the flow through the atrioventricular valve can be modified and regurgitation minimized. In a preferred aspect of the present invention, the chordae will be initially grasped or captured and manipulated to temporarily apply tension to the valve leaflets. The effect of such temporary shortening can then be visually assessed and, if a desired improvement in valve performance is observed, energy can be applied to shorten the chordae. In many cases, however, it may be preferable to apply a clip, ring, suture loop, or other mechanical element to permanently twist, plicate, or otherwise shorten the chordae, as described elsewhere herein.

[0027] In a fourth aspect of the method of the present invention, the tissue structure comprises the valve annulus and the engaging step comprises circumferentially tightening or shortening the annulus. In a preferred technique, the annulus will be strengthened by positioning and attaching a supporting structure over the annulus in a manner broadly analogous to the open surgical placement of an annuloplasty ring. Alternatively, the annulus can be tightened by surgical plication techniques, or in some instances by shrinking tissue within the annulus by applying radiofrequency energy as generally described above in connection with shortening of the chordae.

[0028] In a fifth aspect of the method of the present invention, the tissue structure comprises the papillary muscles and the engaging step comprises capturing and drawing opposed points or portions of the papillary muscles together. This approach is similar in many respects to capture of the chordae, and will generally comprise suturing or otherwise forming a linkage between the opposed portions of the papillary muscles. As with the chordae, it will generally not be desirable to fully close the papillary muscles together, although in some instances such an approach may also find use.

[0029] In all the aspects of the method described above, the heart will usually remain beating while the interventional tool is engaged against the tissue structure. When the heart is beating, however, it may be desirable to temporarily stop valve action during at least a portion of the procedure, particularly to facilitate grasping of the valve leaflets when such a technique is being employed. The valve action can be slowed temporarily by decreasing the heart rate with intravenous infusion of a beta blocker, such as esmolol, or can be completely stopped for a brief time, e.g., five to ten seconds, by infusion of a drug, such as adenosine. Alternatively, the valve action can be stopped by temporarily raising the pressure in the associated ventricle to a pressure above that in the atrium during diastole. While the heart will continue to beat, the motion of the valve leaflets opening and closing will be stopped to facilitate grasping. As a further alternative, it will be possible to mechanically restrain the leaflets directly or by capturing the chordae, as described in more detail below. While such an approach may be effective for some purposes, the difficulty in capturing the valve leaflets initially may still be present.

[0030] While the methods of the present invention are particularly desirable since they permit interventions to occur without stopping the heart, they may also be used with patients undergoing cardiopulmonary bypass. Such cardiopulmonary bypass can be achieved by any presently available technique, including both conventional systems and recently developed endovascular bypass systems, such as those available from Heartport, Inc., Redwood City, Calif.

[0031] During the procedures performed while the heart is beating, it will often be desirable to stabilize the interventional tool against one or more cardiac structures prior to grasping the leaflets with the interventional tool. Such stabilization will lessen the relative motion between the tool and the structure. Stabilization mechanisms may be separate from or integral with any part of the system or device, including but not limited to guidewires, guiding catheters and interventional tools. Likewise, the stabilization mechanisms may provide one or more additional functions in the tissue modification procedure, such as steering, orientation assessment, grasping, coaptation, adjustment and fixation. Therefore, many components in the system may have dual purposes.

[0032] Coaptation may be performed by a number of methods, such as capturing the leaflets or by releasably capturing the chordae attached to each leaflet. An exemplary capture device will comprise a snare, or a pair of snares, which are advanced through the chordae to capture or entangle individual chordae. This snare or snares may then be tightened to draw the chordae partially together and limit valve motion, at least partially. After such coaptation is achieved, the valve leaflets, chordae, papillary muscles, or annulus may then be engaged and modified, e.g., the leaflets may be attached, using a separate interventional tool, as described above and elsewhere herein. Alternatively, it will be possible to form a permanent link, bridge, or capture of the chordae if the temporary coaptation appears sufficient to repair valve function. In some instances, it may be sufficient to simply detach the snare or other capture mechanism and leave it in place permanently. In other instances, it will be possible to exchange the snare for a more permanent attachment structure, such as a suture loop or metallic coil. For example, once the snare is in place, if the valve function is acceptably repaired, the snare may be drawn out from the chordae through the placement catheter, where the snare pulls a length of suture in the manner of a needle passing through tissue. The suture can then be tied or otherwise fastened to form a permanent capture loop for the chordae. Alternatively, a separate attachment structure, such as a metal coil, barb, malecot, or the like, may be advanced around the snared chordae to effect permanent capture, where a structure will be detached and left in place.

[0033] The methods described above may be performed using either antegrade or retrograde endovascular access through the vasculature. The following description will describe both antegrade and retrograde access approaches for gaining access to the mitral valve. Mitral valve access is generally more difficult than tricuspid valve access. In a retrograde approach, the interventional tool, optional guiding catheter, and any other supporting devices, will be introduced through distal arterial vasculature and over the aortic arch and into the left ventricle through the aortic valve. Typically, the aortic arch or via a brachial approach will be approached through a conventional femoral artery access route, but could also be approached through the brachial artery, axillary artery, or a carotid artery. When entering the left ventricle, the interventional tool will generally be directed downwardly and away from the mitral valve structure. Thus, the interventional tool will usually be curved or turned so that it approaches the mitral valve from below, usually through the chordae toward the valve annulus. For example, the interventional tool can enter the left ventricle through the aortic valve and then be deflected or otherwise steered to turn 90° to directly approach the mitral valve and chordae. Steering of the tool can be accomplished by deflecting a supporting catheter using pull wires, pre-formed curved catheters, or the like. In some instances, the papillary muscles could be more directly accessed since they generally lie below the aortic valve and inline with the tool as it enters the left ventricle.

[0034] Often, it will be desirable to position the interventional tool toward the target tissue structure using a preformed and/or steerable guide catheter. In a retrograde approach, the guide catheter may be placed from an access point, e.g., the femoral artery at the patient's groin, so that it passes over the aortic arch, through the aortic valve, and into the left ventricle where it will form an access path to the target tissue structure. When the tissue structure is the chordae or valve leaflets, the guide catheter will usually have to be curved or be everted or turned backward so that it can turn the interventional tool around. Additionally, it may be desirable to provide for stabilization of the distal end of the guide catheter. Stabilization may be provided by extendible elements, wires, cages, balloons, or other structures which engage the valve annulus, chordae or ventricular wall portions. Alternatively, two or more stabilizing extensions may be provided to project forwardly from the guide catheter and seat in the valve commissures to position and hold the guide catheter in place. Such extendible elements may also be used to stabilize guidewires, interventional tools and other types of catheter systems. Specific stabilization structures will be described in more detail below.

[0035] Access for an antegrade endovascular approach will be through the inferior vena cava or superior vena cava into the right atrium. Such antegrade access may, in itself, be sufficient to perform procedures on the tricuspid valve from the top of the valve. Such procedures, however, will not be described in detail herein. To access the mitral valve, it will be necessary to pass from the right atrium into the left atrium, typically by passing the tool through the interatrial septum. The interatrial septum may be endovascularly penetrated by conventional techniques, typically using a Brockenbrough needle, as described in the valvuloplasty literature. Once the interatrial septum has been penetrated, the interventional tool may be passed into the left atrium so that it approaches the mitral valve from the top. Such an approach will require that the access path turn downward, typically through an angle in the range from 0° to 120°.

[0036] The superior vena cava may be accessed through a variety of conventional peripheral access sites, such as the internal jugular vein, while the inferior vena cava may be accessed through the femoral vein. Such access may be performed percutaneously or by surgical cut down techniques.

[0037] As with the retrograde arterial approach, the antegrade venous approach may utilize placement of a guide catheter. With the use of a guidewire, the guide catheter will be configured to pass from the initial access location, through either the superior vena cava or inferior vena cava into the right atrium. The guide catheter will then be adapted to pass through an interatrial penetration and into the left atrium, where it will be pre-shaped or deflected to approach the mitral valve from the top. The guidewire, guide catheter and/or the interventional catheter which carries the interventional tool may be steerable and may optionally have stabilizing elements. For example, in this specific embodiment, the guide catheter may have two or more laterally extensible steering wires and/or a plurality of stabilizing arms which project forwardly and seat around the valve annulus or commissures to hold the guide catheter in place. The interventional tool may then be deployed through the guide catheter to perform the desired valve repair technique.

[0038] Systems according to the present invention comprise a guide catheter configured to pass from the remote vasculature of a patient to a position within the heart adjacent to a target atrioventricular or other cardiac valve. The systems further comprise an interventional catheter configured to pass through the guide catheter and to engage the atrioventricular or other cardiac valve and/or associated cardiac structures and an interventional tool on the interventional catheter adapted to modify the atrioventricular or other cardiac valve leaflets, valve annulus, valve chordae or papillary muscles to reduce regurgitation. In particular, the guide catheter can be configured for either an antegrade or retrograde approach to the mitral valve, as described above. The guide catheter may further comprise a stabilizing element for engaging tissue within the heart to reduce relative movement between the guide catheter and the tissue while the heart remains beating. The structure can be any of the cages, wires, or the like, which have previously been described in connection with the method. Additionally, the interventional catheter may also comprise a stabilizing element for engaging a tissue structure within the heart to reduce relative motion between the interventional catheter and the tissue. The stabilizing element can also be an expansible cage, steering wires, or the like and may include vacuum and/or surface finishes to enhancing coupling. Specific interventional tools include suturing devices, stapling devices, clip-applying devices, radiofrequency electrodes, surgical adhesive applicators, annuloplasty rings, and the like.

[0039] Both the interventional tool and the guide catheter may employ stabilizing mechanisms intended to engage a tissue structure within the heart to reduce relative movement between the interventional tool and/or guide catheter relative to the heart, and in particular relative to the atrioventricular valve. The stabilization mechanisms in both cases may be the same. Typically, the stabilization mechanisms will be adapted to engage at least one tissue structure selected from the group consisting of the interatrial septum, the atrial wall, the valve annulus, the valve commissures, the valve chordae, and the papillary muscles. For example, the stabilizing mechanism may comprise one or more extensible wires which are deployable radially outwardly to engage the tissue structure, such as the valve commissures. Alternatively, the stabilizing mechanism could comprise an expansible cage that can be deployed to occupy all or at least a major portion of the atrium above the atrioventricular valve. As a still further alternative, the stabilizing mechanism could be a pair of inflatable balloons which are spaced-apart and adapted to engage the interatrial septum when the interventional tool and/or guide catheter are passed therethrough.

[0040] In further specific aspects of the systems of the present invention, the interventional tool may comprise a valve leaflet capture device intended for temporarily holding the valve leaflets prior to modification, e.g., affixation. For example, the valve leaflet capture device may comprise a pair of extensible elements which may be advanced from a distal end of the interventional tool to engage and capture the two mitral valve leaflets or three aortic valve leaflets. The particular capture tools may grasp the leaflets by pinching, partially or fully penetrating or piercing, and/or suctioning the leaflets. The tools may comprise jawed devices, looped devices, coiled devices or pronged devices, or vacuum devices to grasp and hold the leaflets.

[0041] The present invention further provides methods for grasping an atrioventricular or other cardiac valve, particularly the mitral valve, to facilitate subsequent intervention or for other purposes. The grasping method comprises capturing chordae attached to at least one leaflet of the valve while the heart is beating. Capture of the chordae from beneath the valve can modify leaflet movement and improve valve function, optionally closing portions of opposed valve leaflets against each other. Usually, chordae attached to valve leaflets (or possibly three valve leaflets in the case of tricuspid valves) are captured simultaneously. For example, one or more snares, such as helical coils, can be advanced into the chordae to capture and immobilize portions thereof. Alternatively, a loop element can be advanced through the valve chordae and tightened in order to modify valve function. In some instances, capture of the chordae can be made permanent and will be sufficient to treat the underlying regurgitation. In other cases, capture of the chordae will be primarily for leaflet coaptation, and the leaflets will be affixed by a subsequent interventional step. Preferably, the subsequent interventional step is performed while the chordae remain captured. The chordae can then be released after the leaflets or other tissue structures have been modified.

[0042] The present invention still further provides a chordae capture catheter comprising a catheter body having a proximal end and a distal end. Means are provided at or near the distal end of the catheter body for capturing the chordae. A first exemplary means comprises one or more coils which are extensible from the distal end of the catheter and which engage and entangle the chordae when they are advanced therein. A second exemplary capture means comprises a loop element which is extensible from the distal end of the catheter and which is pre-formed to pass through the chordae on one or both, preferably both valve leaflets in order to draw the chordae together and modify valve function.

[0043] A further method according to the present invention for grasping an atrioventricular or other cardiac valve leaflets comprises capturing two valve leaflets separately and preferably sequentially. Such capture is effected by a leaflet capture catheter having at least three grasping jaws or prongs. A first valve leaflet is captured between a first pair of prongs, and second valve leaflet is captured between a second pair of prongs. Optionally, the two prong pairs can have a common center prong, typically where the center prong is fixed (immobile) and the two outer prongs pivot in order to provide a pair of adjacent jaw-type graspers. By separately and sequentially grasping the two leaflets, the leaflets can be held in a preferred apposition and the improvement in valve function observed. Alternatively, the leaflets may be grasped simultaneously. If the improvement is adequate, the valves can be permanently affixed in a separate step. Optionally, the leaflet capture catheter can include a device for fixing the valves, e.g., it can carry a clip which can be applied on to the valves as the capture catheter is withdrawn.

[0044] The present invention still further provides leaflet capture catheters suited for performing the method just described. The catheters comprise a catheter body having a proximal end and a distal end. A leaflet grasper is provided at or near the distal end of the catheter body and includes at least three prongs wherein at least two of the three prongs are pivotable so that they may be separately actuated to separately capture individual leaflets or simultaneously actuated to capture the leaflets together. Optionally, the catheters further comprise means for affixing the valve leaflets after they have been captured, preferably comprising a clip-applier.

[0045] The present invention further includes leaflet capture catheters and tools which utilize a vacuum for grasping the valve leaflets and manipulating the post leaflets into a desired apposition. Usually, the catheter will have at least two vacuum channels at a distal end where the channels are preferably separately positionable and independently actuable. In that way, at least two valve leaflets can be separately captured and positioned while the base catheter remains stationary. The catheter may be positioned in an antegrade or retrograde manner with the tool entering between the valve leaflets and optionally between the chordae. The tool and/or catheter may optionally further include modification devices, such as suture appliers, clip appliers, staplers, rivet appliers, adhesive applicators, heating elements for shortening the chordae, and others of the specific interventional tools described hereinafter. Likewise, the present invention further includes catheters and tools which include lumens for monitoring pressures within the chambers of the heart, and/or infusion of radiopaque contrast solution.