Abstract:
The invention provides devices, systems and methods for tissue approximation and repair at treatment sites. The devices, systems and methods of the invention will find use in a variety of therapeutic procedures, including endovascular, minimally-invasive, and open surgical procedures, and can be used in various anatomical regions, including the abdomen, thorax, cardiovascular system, heart, intestinal tract, stomach, urinary tract, bladder, lung, and other organs, vessels, and tissues. The invention is particularly useful in those procedures requiring minimally-invasive or endovascular access to remote tissue locations, where the instruments utilized must negotiate long, narrow, and tortuous pathways to the treatment site. In addition, many of the devices and systems of the invention are adapted to be reversible and removable from the patient at any point without interference with or trauma to internal tissues.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional of U.S. patent application Ser. No. 13/231,586 filed Sep. 13, 2011, the entire contents of which is incorporated herein by reference. 
     
    
     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, percutaneous or minimally invasive surgical treatment of bodily tissues, such as tissue approximation or valve repair. More particularly, the present invention relates to repair of valves of the heart and venous valves. 
         [0004]    Surgical repair of bodily tissues often involves tissue approximation and fastening of such tissues in the approximated arrangement. When repairing valves, tissue approximation includes coapting the leaflets of the valves in a therapeutic arrangement which may then be maintained by fastening or fixing the leaflets. Such coaptation can be used to treat regurgitation which most commonly occurs in the mitral valve. 
         [0005]    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. 
         [0006]    Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve or the left ventricular wall. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, the papillary muscles or the left ventricular wall 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. 
         [0007]    The most common treatments for mitral valve regurgitation rely on valve replacement or repair including leaflet and annulus remodeling, the latter 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&#39;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 high mortality and morbidity. More recently, minimially invasive catheter based procedures have been developed to deliver implantable clips to the incompetent valve. These clips are used to fasten a portion of the valve leaflets together, thereby reducing the regurgitation. While the clips appear to be promising, delivery and deployment of the clip can be challenging. In some situations, it may be challenging to visualize the clip and valve leaflets using techniques such as fluoroscopy and echocardiography. Therefore, improved attachment mechanisms and attachment evaluation methods would be desirable. 
         [0008]    For these reasons, it would be desirable to provide improved methods, devices, and systems for performing the repair of mitral and other cardiac valves. Such methods, devices, and systems should preferably not require open chest access and be capable of being performed either endovascularly, i.e., using devices which are advanced to the heart from a point in the patient&#39;s vasculature remote from the heart or by a minimally invasive approach. Further, such devices and systems should provide features which allow easier delivery of fixation devices, as well as repositioning and optional removal of the fixation device prior to fixation to ensure optimal placement. Still more preferably, the methods, devices, and systems would be useful for repair of tissues in the body other than heart valves. At least some of these objectives will be met by the inventions described hereinbelow. 
         [0009]    2. Description of the Background Art 
         [0010]    Minimally invasive and percutaneous techniques for coapting and modifying mitral valve leaflets to treat mitral valve regurgitation are described in PCT Publication Nos. WO 98/35638; WO 99/00059; WO 99/01377; and WO 00/03759. 
         [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. 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. 
         [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.  48:670-676. 
         [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 PCT Publication No. 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 invention provides devices, systems and methods for tissue approximation and repair at treatment sites. The devices, systems and methods of the invention will find use in a variety of therapeutic procedures, including endovascular, minimally-invasive, and open surgical procedures, and can be used in various anatomical regions, including the abdomen, thorax, cardiovascular system, heart, intestinal tract, stomach, urinary tract, bladder, lung, and other organs, vessels, and tissues. The invention is particularly useful in those procedures requiring minimally-invasive or endovascular access to remote tissue locations, where the instruments utilized must negotiate long, narrow, and tortuous pathways to the treatment site. In addition, many of the devices and systems of the invention are adapted to be reversible and removable from the patient at any point without interference with or trauma to internal tissues. 
         [0018]    In preferred embodiments, the devices, systems and methods of the invention are adapted for fixation of tissue at a treatment site. Exemplary tissue fixation applications include cardiac valve repair, septal defect repair, vascular ligation and clamping, laceration repair and wound closure, but the invention may find use in a wide variety of tissue approximation and repair procedures. In a particularly preferred embodiment, the devices, systems and methods of the invention are adapted for repair of cardiac valves, and particularly the mitral valve, as a therapy for regurgitation. The invention enables two or more valve leaflets to be coapted using an “edge-to-edge” or “bow-tie” technique to reduce regurgitation, yet does not require open surgery through the chest and heart wall as in conventional approaches. Using the devices, systems and methods of the invention, the mitral valve can be accessed from a remote surgical or vascular access point and the two valve leaflets may be coapted using endovascular or minimally invasive approaches. While less preferred, in some circumstances the invention may also find application in open surgical approaches as well. According to the invention, the mitral valve may be approached either from the atrial side (antegrade approach) or the ventricular side (retrograde approach), and either through blood vessels or through the heart wall. 
         [0019]    The devices, systems and methods of the invention are centered on variety of devices which may be used individually or in a variety of combinations to form interventional systems. In preferred embodiments, the interventional system includes a multi-catheter guiding system, a delivery catheter and an interventional device. Each of these components will be discussed herein. 
         [0020]    In a first aspect of the present invention, a system for fixing tissue comprises an implantable tissue fixation device comprising a pair of fixation elements each having a first end, a free end opposite the first end, and an engagement surface therebetween for engaging the tissue. The fixation device further comprises a pair of gripping elements. Each gripping element is moveable with respect to one of the fixation elements and is disposed in opposition to one of the engagement surfaces so as to capture tissue therebetween. The system also comprises a gripper pusher releasably coupled to the implantable fixation device adjacent the pair of gripping elements. The gripper pusher has an expanded configuration and a collapsed configuration. In the expanded configuration the gripper pusher engages the pair of gripping elements and advances the pair of gripping elements toward the engagement surfaces of the fixation elements. In the collapsed configuration the gripper pusher has a reduced radial profile relative to the gripper pusher radial profile in the expanded configuration thereby allowing the pair of gripping elements to move away from the engagement surfaces of the fixation elements. 
         [0021]    The first ends of the fixation elements may be movably coupled together such that the fixation elements are moveable between a closed position and an inverted position. In the closed position, the engagement surfaces may face each other, and in the inverted position the engagement surfaces may face away from each other. Each fixation element may be at least partially concave such that each gripping element is separated from an opposing engagement surface in an undeployed configuration, and each gripping element may be at least partially recessed within a fixation element in a deployed configuration. The fixation elements may be further moveable to an open position between the closed position and the inverted position. 
         [0022]    The gripping elements may be movable independently of the fixation elements. They may be biased toward the engagement surfaces. The gripping elements may be approximately parallel to each other in an undeployed configuration. 
         [0023]    The gripper pusher may comprise a spring element that moves from the collapsed configuration to the expanded configuration when a compressive force is applied thereto. 
         [0024]    The spring element may comprise a longitudinal axis, and the compressive force may be applied in a direction substantially parallel thereto. The spring element may be resiliently biased to return to the collapsed configuration when the compressive force is released. The spring element may be resiliently biased to return to the expanded configuration. The gripper pusher may comprise two spring elements, or an elongate deflectable arm. The arm may comprise a plurality of peaks or bowed regions. The deflectable arm may be biased to return to the expanded configuration, and proximal retraction of the proximal elements may collapse the deflectable arm from the expanded configuration to the collapsed configuration. 
         [0025]    The gripper pusher may comprise an attachment mechanism for releasably attaching a distal portion of the gripper pusher to the implantable fixation device. The attachment mechanism may comprise a notched region on a distal portion of the gripper pusher, and a boss adjacent a proximal end of the implantable fixation device. The notched region may be sized to accept the boss. The system may further comprise an elongate delivery shaft having a proximal portion and a distal portion. The distal portion of the elongate delivery shaft may be releasably coupled to a proximal portion of the gripper pusher. The gripper pusher may comprise an attachment ring or coupling ring that may be coupled to the proximal portion thereof, and the attachment ring may be slidably disposed over the delivery shaft. 
         [0026]    The system may further comprise an actuation mechanism that may be coupled to the fixation elements, and that is adapted to move the fixation elements between the closed position and the inverted position. The system may also comprise a coupling member for detachably coupling the fixation device to an elongate delivery shaft. A covering may be disposed on the fixation elements that is adapted to promote tissue ingrowth. A coating may be disposed on the fixation elements that is adapted to deliver a therapeutic agent to the treatment tissue. 
         [0027]    In another aspect of the invention, a system for fixing tissue may comprise an implantable tissue fixation device and a first gripper actuator. The implantable tissue fixation device comprises a pair of fixation elements and a pair of gripping elements. The pair of fixation elements comprises a first fixation element and a second fixation element. Each fixation element has a first end, a free end opposite the first end, and an engagement surface therebetween for engaging the tissue. The pair of gripping elements comprises a first gripping element and a second gripping element. The first gripping element is moveable with respect to the first fixation element. The first gripping element is also disposed in opposition to the engagement surface of the first fixation element so as to capture tissue therebetween. Similarly, the second gripping element is moveable with respect to the second fixation element and is disposed in opposition to the engagement surface of the second fixation element so as to capture tissue therebetween. The first gripper actuator is releaseably coupled to the implantable fixation device adjacent to the first gripping element. The first gripper actuator has a first configuration and a second configuration. Actuating the first gripper actuator between the first configuration and the second configuration moves the first gripping element with respect to the first fixation element. Typically, the system further comprises a second gripper actuator. The second gripper actuator is releaseably coupled to the implantable fixation device adjacent to the second gripping element. The second gripper actuator similarly has a first configuration and a second configuration. Actuating the second gripper actuator between the first configuration and the second configuration moves the second gripping element with respect to the second fixation element. The first gripper actuator and the second gripper actuator are actuatable between their first configurations and their second configurations independently of each other. 
         [0028]    In many embodiments, the first ends are movably coupled together such that the fixation elements are moveable between a closed position and an inverted position. In the closed position, the first ends of the pair of fixation elements have their engagement surfaces facing each other. In the open position, the first ends of the pair of fixation elements have their engagement surfaces facing away from each other. The system may further comprise an actuation mechanism coupled to the fixation elements. The actuation mechanism is adapted to move the fixation elements between the closed position and the inverted position. 
         [0029]    In many embodiments, each fixation element is at least partially concave. By being at least partially concave, each gripping element is separated from an opposing engagement surface in an undeployed configuration and may be at least partially recessed within the fixation element in a deployed configuration. The fixation elements may further be moveable to an open position between the closed position and the inverted position. 
         [0030]    In addition to being independently moveable relative to one another, the gripping elements may be movable independently of the fixation elements. The gripping elements may be biased toward the engagement surfaces. The gripping elements may be approximately parallel to each other in an undeployed configuration. 
         [0031]    In many embodiments, the system further comprises a gripper pusher as described above. The gripper pusher is releasably coupled to the implantable fixation device adjacent the pair of gripping elements. The gripper pusher has an expanded configuration and a collapsed configuration. In the expanded configuration, the gripper pusher engages one or more of the pair of gripping elements and advances one or more of the pair of gripping elements toward the engagement surfaces of the fixation elements. In the collapsed configuration, the gripper pusher has a reduced radial profile relative to the gripper pusher radial profile in the expanded configuration. This reduced radial profile allows the pair of gripping elements to move away from the engagement surfaces of the fixation elements. 
         [0032]    In many embodiments, the first gripper actuator comprises a first wire and the second gripper actuator comprises a second wire. The first wire and the second wire may be substantially flat or have other profiles such as round, square, elliptical, etc. Preferably, the substantially flat sides of the first and second wire are positioned to engage the first and second gripping elements and are biased to bend or flex along the flat side. Thus, as the first and second wires are advanced, they will tend to deflect in the direction toward the first and second gripping elements. 
         [0033]    In many embodiments, at least one of a distal end of the first gripper actuator or a distal end of the second gripper actuator is releaseably coupled to the implantation fixation device by a suture knot. 
         [0034]    In many embodiments, the system further comprises an elongate delivery shaft having a proximal portion and a distal portion. The distal portion of the elongate delivery shaft is releasably coupled to a proximal portion of the fixation device. Each of the first and second gripper actuators may comprise distal portions. The distal portions of the first and second gripper actuators may be releasably coupled to at least one of the distal portion of the elongate delivery shaft or the proximal portion of the fixation device. For example, the distal portions of the first gripper actuator and second gripper actuator may each comprise a closed loop or a coiled distal end disposed over at least one of the distal portion of the elongate delivery shaft or the proximal portion of the fixation device. 
         [0035]    In many embodiments, the proximal portion of the fixation device comprises a channel having a pair of notches. The distal portion of the elongate delivery shaft comprises a pair of L-shaped ends resiliently biased to fit into the pair of notches. The distal portion of the elongate delivery shaft is releasably coupled to the proximal portion of the fixation device by placing the pair of L-shaped ends into channel of the fixation device and locking the pair of notches in the channel. The first and second gripper actuators each comprise distal ends. Placing the distal ends of the first and second gripper actuators and coupling the distal portion of the elongate delivery shaft to the proximal portion of the fixation device locks the distal ends of the first and second gripper actuators in place. The first and second gripper actuator may each comprise T-shaped distal ends. The system may further comprise a covering assembly coupled to and disposed over the distal portion of the elongate delivery shaft. The covering assembly comprises an outer slideable section and an inner section having a pair of T-shaped openings. The first and second gripper actuator are releaseably coupled to the fixation device by sliding the T-shaped distal ends of the first and second gripper actuators into the pair of the T-shaped opening of the inner section of the covering assembly and sliding the outer slideable section to cover the T-shaped openings. 
         [0036]    In many embodiments, the first and second gripper actuators are releaseably coupled to the first and second gripping elements, respectively. The first and second gripping elements may each comprise portions extending radially outward. The system may further comprise first and second holding elements. The first holding element is coupled to the first gripper actuator and releaseably coupled to the first gripping element at its portion extending radially outward. The second holding element is coupled to the second gripper actuator and releaseably coupled to the second gripping element at its portion extending radially outward. The first and second holding element may comprises a first and second ring, respectively. The rings are disposed over the portions extending radially outward of their respective gripping elements. Alternatively, the first and second holding elements may comprise a first and second clip, respectively. The clips are releaseably attached to the portion extending radially outward of their respective gripping elements. The first and second clips may each comprise a pair of legs disposed over the length of their respective gripping elements. The portions extending radially outward of the first and second gripping elements may each have apertures. The first and second gripper actuators may be threaded through the apertures of the radially outward portion of the first and second gripping elements, respectively. The first and second gripper actuators may each comprise an enlarged portion. The diameters of the enlarged portions of the first and second gripper actuator may be greater than that of the aperture of the portion extending radially outward of the first and second gripping elements, respectively, to facilitate moving the first and second gripping elements. The enlarged portions of the first and second gripper actuator may comprises a sleeve disposed over the first and second gripper actuators. 
         [0037]    In many embodiments, the first and second gripper actuator and the second gripper actuator each comprise an actuation line and a release line. Each actuation line may comprise a loop while each release line may comprises a single release cable. The single release cable is threaded through the loop of the actuation line when a gripper actuator is coupled a gripping element. Pulling the single release cable out through the loop of the actuation line allows a gripper actuator to be released from a gripping element. 
         [0038]    The system may further comprise a coupling member for detachably coupling the fixation device to an elongate delivery shaft, a covering on the fixation elements adapted for promoting tissue growth, and/or a coating on the fixation elements adapted for delivering a therapeutic agent. 
         [0039]    Another aspect of the invention provides a method for fixing tissue. An implantable tissue fixation device is provided. The fixation device comprises a pair of fixation elements. Each fixation element has a first end, a free end opposite the first end, and an engagement surface therebetween for engaging the tissue. The fixation device further comprises a pair of gripping elements. Each gripping element is moveable with respect to one of the fixation elements and is disposed in apposition to one of the engagement surfaces so as to capture tissue therebetween. The fixation element is positioned relative to tissue so that the tissue is disposed between the pair of gripping elements and the engagement surfaces of the pair of fixation element. The pair of gripping elements is advanced toward the engagement surfaces of the fixation elements. 
         [0040]    In many embodiments, a gripper pusher releasably coupled to the implantable fixation device adjacent the pair of gripping elements is provided, and the pair of gripping elements is advanced toward the engagement surfaces of the fixation elements by engaging the pair of gripping elements with the gripper pusher. Engaging the pair of gripping elements with the gripper pusher may comprise placing the gripper pusher into an expanded configuration from a collapsed configuration. The gripper pusher may comprise a spring element having a longitudinal axis, and the pair of gripping elements may be engaged with the gripper pusher by applying a compressive force to the spring element in a direction substantially parallel to the longitudinal axis to move the gripper pusher to the expanded configuration. The gripper pusher may be placed into the collapsed configuration from the expanded configuration to reduce the radial profile of the gripper pusher relative to the gripper pusher radial profile in the expanded configuration to allow the pair of gripping elements to move away from the engagement surfaces of the fixation elements. 
         [0041]    In many embodiments, the first ends of the pair of the fixation elements is moved between a closed position to an inverted position. The engagement surfaces face each other when the fixation element is in the closed position and away from each other when the fixation element is in the inverted position. The fixation elements may be moved to an open position between the closed position and the inverted position. 
         [0042]    Another aspect of the invention provides a method of fixing tissue. An implantable tissue fixation device is provided. The fixation device comprises a pair of fixation elements, which comprises a first fixation element and a second fixation element. Each fixation element has a first end, a free end opposite the first end, and an engagement surface therebetween for engaging the tissue. The fixation device further comprises a pair of gripping elements, which comprise a first gripping element and a second gripping element. The first gripping element is disposed in apposition to the engagement surface of the first fixation element. The second gripping element is likewise disposed in apposition to the engagement surface of the second fixation element. The fixation element is positioned relative to tissue so that the tissue is disposed between the first gripping element and the engagement surface of the first fixation element. The tissue is captured between the first gripping element and the engagement surface of the first fixation element by moving the first gripping element with respect to the first fixation element. The position of the second gripping element is maintained with respect to the second fixation element while the first gripping element is moved with respect to the first fixation element. 
         [0043]    In many embodiments, a first gripping element actuator coupled to the first gripping element and a second gripping element actuator coupled to the second gripping element are provided. The tissue between the first gripping element and the engagement surface of the first fixation element may be captured by moving the first gripping element actuator to move the first gripping element. The position of the second gripping element with respect to the second fixation element may be maintained by holding the second gripping element actuator stationary relative to the second gripping element. 
         [0044]    In many embodiments, the captured tissue between the first gripping element and the engagement surface of the first fixation element is released by moving the first gripping element away from the first fixation element. The fixation can then be repositioned relative to the tissue. 
         [0045]    In many embodiments, the fixation element is positioned relative to tissue so that the tissue is disposed between the second gripping element and the engagement surface of the second fixation element. The tissue between the second gripping element and the engagement surface of the second fixation element may be captured by moving the second gripping element with respect to the second fixation element. In some embodiments, the captured tissue between the pair of gripping elements and the engagement surfaces of the pair of fixation elements can be released by moving the pair of gripping elements away from the engagement surfaces of the pair of fixation elements. The fixation can then be repositioned relative to the tissue. 
         [0046]    Other aspects of the nature and advantages of the invention are set forth in the detailed description set forth below, taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0047]      FIG. 1  illustrates the left ventricle and left atrium of the heart during systole. 
           [0048]      FIG. 2A  illustrates free edges of leaflets in normal coaptation, and  FIG. 2B  illustrates the free edges in regurgitative coaptation. 
           [0049]      FIGS. 3A-3C  illustrate grasping of the leaflets with a fixation device, inversion of the distal elements of the fixation device and removal of the fixation device, respectively. 
           [0050]      FIG. 4  illustrates the position of the fixation device in a desired orientation relative to the leaflets. 
           [0051]      FIGS. 5A-5B  and  6 A- 6 B illustrate exemplary embodiments of coupling mechanisms of the instant application. 
           [0052]      FIG. 7  illustrates an embodiment of the fixation device of the present invention. 
           [0053]      FIGS. 8A-8B ,  9 A- 9 B,  10 A- 10 B,  11 A- 11 B, and  12 - 14  illustrate the fixation device of  FIG. 7  in various possible positions during introduction and placement of the device within the body to perform a therapeutic procedure. 
           [0054]      FIGS. 15A-15H  illustrate the fixation device of  FIG. 7  with a gripper pusher. 
           [0055]      FIGS. 15I-15V  illustrate the fixation device of  FIG. 7  with independently actuatable proximal elements. 
           [0056]    FIGS.  15 W 1 - 15 AB 7  illustrate various embodiments of coupling a proximal element line to a proximal element of the fixation device of  FIG. 7 . 
           [0057]    FIGS.  15 AC 1 - 15 AC 4  illustrate various control mechanisms of the independently actuatable proximal element lines of the fixation device of  FIGS. 15I-15V . 
           [0058]      FIGS. 16A-16C  illustrate a covering on the fixation device wherein the device is in various positions. 
           [0059]      FIG. 17  illustrates an embodiment of the fixation device including proximal elements and a locking mechanism. 
           [0060]      FIG. 18  provides a cross-sectional view of the locking mechanism of  FIG. 17 . 
           [0061]      FIGS. 19-20  provide a cross-sectional view of the locking mechanism in the unlocked and locked positions respectively. 
           [0062]    FIGS.  21  and  22 A- 22 B illustrate another embodiment of a locking mechanism. 
           [0063]    FIGS.  23  and  24 A- 24 B illustrate yet another embodiment of a locking mechanism. 
           [0064]      FIG. 25  is a perspective view of an embodiment of a delivery catheter for a fixation device. 
           [0065]      FIG. 26  illustrates an embodiment of a fixation device coupled to the distal end of a delivery catheter. 
           [0066]      FIG. 27  illustrates a portion of the shaft of a delivery catheter and a fixation device which is coupleable with the catheter. 
           [0067]      FIGS. 28A-28B  illustrate an exemplary embodiment of an actuator rod assembly. 
           [0068]      FIGS. 29A-28B ,  30 A- 30 B,  31 A- 31 B, and  32 A- 32 B illustrate layers of an exemplary cable used in the actuator rod of  FIGS. 28A-28B . 
           [0069]      FIGS. 33A-33B ,  34 A- 34 B,  35 A- 35 B,  36 A- 36 B, and  37 A- 37 B illustrate layers in another exemplary cable used in the actuator rod of  FIGS. 28A-28B . 
           [0070]      FIGS. 38-40  are cross-sectional views of embodiments of the shaft of the delivery catheter. 
           [0071]      FIGS. 40A-40B  illustrate embodiments of the nose of the shaft of the delivery catheter. 
           [0072]      FIG. 41A-41C  illustrate various arrangements of lock lines engaging release harnesses of a locking mechanism. 
           [0073]      FIGS. 42A-42B  illustrate various arrangements of proximal element lines engaging proximal elements of a fixation device. 
           [0074]      FIG. 43  illustrates an embodiment of the handle of the delivery catheter. 
           [0075]      FIG. 44  is a cross-sectional view of the main body of the handle. 
           [0076]      FIG. 45  illustrates an embodiment of a lock line handle. 
           [0077]      FIG. 45A  illustrates the lock line handle of  FIG. 45  positioned within a semi-tube which is disposed within the sealed chamber. 
           [0078]      FIGS. 46A-46B  illustrate a mechanism for applying tension to lock lines. 
           [0079]    FIGS.  47  and  47 A- 47 B illustrate features of the actuator rod control and handle. 
           [0080]      FIG. 48  is a perspective view of an embodiment of a multi-catheter guiding system of the present invention, and an interventional catheter positioned therethrough. 
           [0081]      FIG. 49A  illustrates a primary curvature in an outer guide catheter. 
           [0082]      FIG. 49B  illustrates a secondary curvature in an inner guide catheter. 
           [0083]      FIGS. 49C-49D  illustrate example movement of an inner guide catheter through angle thetas. 
           [0084]      FIG. 50A  is a perspective side view of a multi-catheter guiding system having an additional curve in the outer guide catheter. 
           [0085]      FIG. 50B  illustrates lifting of the outer guide catheter due to the additional curve of  FIG. 49A . 
           [0086]      FIGS. 51A-51D  illustrate a method of using the multi-catheter guiding system for accessing the mitral valve. 
           [0087]      FIGS. 52A-52D  illustrate curvature of a guide catheter of the present invention by the actuation of one or more pullwires. 
           [0088]      FIG. 52E  illustrates attachment of a pullwire to a tip ring. 
           [0089]      FIGS. 53A-53I  illustrate embodiments of the present invention comprising sections constructed with the inclusion of braiding or a coil. 
           [0090]      FIGS. 54A-54C  illustrate a keying feature of the present invention. 
           [0091]      FIGS. 55A-55B  are perspective views of a guide catheter including a series of articulating members. 
           [0092]      FIG. 56  illustrates embodiments of the handles. 
           [0093]      FIG. 57  illustrates the handles of  FIG. 56  with a portion of the housing removed. 
           [0094]      FIG. 58  illustrates steering mechanisms within a handle. 
           [0095]      FIG. 59  illustrates attachment of a pullwire to a disk. 
           [0096]      FIGS. 60A-60B  illustrate a hard stop peg restricting rotation of a disk. 
           [0097]      FIGS. 61A-61C  illustrates a portion of a hard stop gear assembly. 
           [0098]      FIGS. 62A-62F  illustrate a ball restricting rotation of a disk. 
           [0099]      FIG. 63  illustrates an embodiment of a friction assembly. 
           [0100]      FIG. 64  illustrates an embodiment of an interventional system of the present invention. 
           [0101]      FIG. 64A  illustrates an embodiment of a hemostatic valve for use with the present invention. 
           [0102]      FIG. 64B  illustrates an embodiment of a fixation device introducer. 
           [0103]      FIG. 65  illustrates another embodiment of an interventional system of the present invention. 
           [0104]      FIGS. 66-68  illustrate an embodiment of a stabilizer base for use with the present invention. 
           [0105]      FIG. 69  illustrates a kit constructed in accordance with the principles of the present invention. 
           [0106]      FIG. 70  illustrates a handle in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     I. Cardiac Physiology 
       [0107]    The left ventricle LV of a normal heart H in systole is illustrated in  FIG. 1 . The left ventricle LV is contracting and blood flows outwardly through the tricuspid (aortic) valve AV in the direction of the arrows. Back flow of blood or “regurgitation” through the mitral valve MV is prevented since the mitral valve is configured as a “check valve” which prevents back flow when pressure in the left ventricle is higher than that in the left atrium LA. The mitral valve MV comprises a pair of leaflets having free edges FE which meet evenly to close, as illustrated in  FIG. 1 . The opposite ends of the leaflets LF are attached to the surrounding heart structure along an annular region referred to as the annulus AN. The free edges FE of the leaflets LF are secured to the lower portions of the left ventricle LV through chordae tendinae CT (referred to hereinafter as the chordae) which include a plurality of branching tendons secured over the lower surfaces of each of the valve leaflets LF. The chordae CT in turn, are attached to the papillary muscles PM which extend upwardly from the lower portions of the left ventricle and intraventricular septum IVS. 
         [0108]    A number of structural defects in the heart can cause mitral valve regurgitation. Regurgitation occurs when the valve leaflets do not close properly allowing leakage from the ventricle into the atrium. As shown in  FIG. 2A , the free edges of the anterior and posterior leaflets normally meet along a line of coaptation C. An example of a defect causing regurgitation is shown in  FIG. 2B . Here an enlargement of the heart causes the mitral annulus to become enlarged, making it impossible for the free edges FE to meet during systole. This results in a gap G which allows blood to leak through the valve during ventricular systole. Ruptured or elongated chordae can also cause a valve leaflet to prolapse since inadequate tension is transmitted to the leaflet via the chordae. While the other leaflet maintains a normal profile, the two valve leaflets do not properly meet and leakage from the left ventricle into the left atrium will occur. Such regurgitation can also occur in patients who have suffered ischemic heart disease where the left ventricle does not contract sufficiently to effect proper closure. 
       II. General Overview 
       [0109]    The present invention provides methods and devices for grasping, approximating and fixating tissues such as valve leaflets to treat cardiac valve regurgitation, particularly mitral valve regurgitation. The present invention also provides features that allow repositioning and removal of the device if so desired, particularly in areas where removal may be hindered by anatomical features such as chordae CT. Such removal would allow the surgeon to reapproach the valve in a new manner if so desired. 
         [0110]    Grasping will preferably be atraumatic providing a number of benefits. By atraumatic, it is meant that the devices and methods of the invention may be applied to the valve leaflets and then removed without causing any significant clinical impairment of leaflet structure or function. The leaflets and valve continue to function substantially the same as before the invention was applied. Thus, some minor penetration or denting of the leaflets may occur using the invention while still meeting the definition of “atraumatic.” This enables the devices of the invention to be applied to a diseased valve and, if desired, removed or repositioned without having negatively affected valve function. In addition, it will be understood that in some cases it may be necessary or desirable to pierce or otherwise permanently affect the leaflets during either grasping, fixing or both. In some of these cases, grasping and fixation may be accomplished by a single device. Although a number of embodiments are provided to achieve these results, a general overview of the basic features will be presented herein. Such features are not intended to limit the scope of the invention and are presented with the aim of providing a basis for descriptions of individual embodiments presented later in the application. 
         [0111]    The devices and methods of the invention rely upon the use of an interventional tool that is positioned near a desired treatment site and used to grasp the target tissue. In endovascular applications, the interventional tool is typically an interventional catheter. In surgical applications, the interventional tool is typically an interventional instrument. In preferred embodiments, fixation of the grasped tissue is accomplished by maintaining grasping with a portion of the interventional tool which is left behind as an implant. While the invention may have a variety of applications for tissue approximation and fixation throughout the body, it is particularly well adapted for the repair of valves, especially cardiac valves such as the mitral valve. Referring to  FIG. 3A , an interventional tool  10 , having a delivery device, such as a shaft  12 , and a fixation device  14 , is illustrated having approached the mitral valve MV from the atrial side and grasped the leaflets LF. The mitral valve may be accessed either surgically or by using endovascular techniques, and either by a retrograde approach through the ventricle or by an antegrade approach through the atrium, as described above. For illustration purposes, an antegrade approach is described. 
         [0112]    The fixation device  14  is releasably attached to the shaft  12  of the interventional tool  10  at its distal end. When describing the devices of the invention herein, “proximal” shall mean the direction toward the end of the device to be manipulated by the user outside the patient&#39;s body, and “distal” shall mean the direction toward the working end of the device that is positioned at the treatment site and away from the user. With respect to the mitral valve, proximal shall refer to the atrial or upstream side of the valve leaflets and distal shall refer to the ventricular or downstream side of the valve leaflets. 
         [0113]    The fixation device  14  typically comprises proximal elements  16  (or gripping elements) and distal elements  18  (or fixation elements) which protrude radially outward and are positionable on opposite sides of the leaflets LF as shown so as to capture or retain the leaflets therebetween. The proximal elements  16  are preferably comprised of cobalt chromium, nitinol or stainless steel, and the distal elements  18  are preferably comprised of cobalt chromium or stainless steel, however any suitable materials may be used. The fixation device  14  is coupleable to the shaft  12  by a coupling mechanism  17 . The coupling mechanism  17  allows the fixation device  14  to detach and be left behind as an implant to hold the leaflets together in the coapted position. 
         [0114]    In some situations, it may be desired to reposition or remove the fixation device  14  after the proximal elements  16 , distal elements  18 , or both have been deployed to capture the leaflets LF. Such repositioning or removal may be desired for a variety of reasons, such as to reapproach the valve in an attempt to achieve better valve function, more optimal positioning of the device  14  on the leaflets, better purchase on the leaflets, to detangle the device  14  from surrounding tissue such as chordae, to exchange the device  14  with one having a different design, or to abort the fixation procedure, to name a few. To facilitate repositioning or removal of the fixation device  14  the distal elements  18  are releasable and optionally invertible to a configuration suitable for withdrawal of the device  14  from the valve without tangling or interfering with or damaging the chordae, leaflets or other tissue.  FIG. 3B  illustrates inversion wherein the distal elements  18  are moveable in the direction of arrows  40  to an inverted position. Likewise, the proximal elements  16  may be raised, if desired. In the inverted position, the device  14  may be repositioned to a desired orientation wherein the distal elements may then be reverted to a grasping position against the leaflets as in  FIG. 3A . Alternatively, the fixation device  14  may be withdrawn (indicated by arrow  42 ) from the leaflets as shown in  FIG. 3C . Such inversion reduces trauma to the leaflets and minimizes any entanglement of the device with surrounding tissues. Once the device  14  has been withdrawn through the valve leaflets, the proximal and distal elements may be moved to a closed position or configuration suitable for removal from the body or for reinsertion through the mitral valve. 
         [0115]      FIG. 4  illustrates the position of the fixation device  14  in a desired orientation in relation to the leaflets LF. This is a short-axis view of the mitral valve MV from the atrial side, therefore, the proximal elements  16  are shown in solid line and the distal elements  18  are shown in dashed line. The proximal and distal elements  16 ,  18  are positioned to be substantially perpendicular to the line of coaptation C. The device  14  may be moved roughly along the line of coaptation to the location of regurgitation. The leaflets LF are held in place so that during diastole, as shown in  FIG. 4 , the leaflets LF remain in position between the elements  16 ,  18  surrounded by openings O which result from the diastolic pressure gradient. Advantageously, leaflets LF are coapted such that their proximal or upstream surfaces are facing each other in a vertical orientation, parallel to the direction of blood flow through mitral valve MV. The upstream surfaces may be brought together so as to be in contact with one another or may be held slightly apart, but will preferably be maintained in the vertical orientation in which the upstream surfaces face each other at the point of coaptation. This simulates the double orifice geometry of a standard surgical bow-tie repair. Color Doppler echo will show if the regurgitation of the valve has been reduced. If the resulting mitral flow pattern is satisfactory, the leaflets may be fixed together in this orientation. If the resulting color Doppler image shows insufficient improvement in mitral regurgitation, the interventional tool  10  may be repositioned. This may be repeated until an optimal result is produced wherein the leaflets LF are held in place. 
         [0116]    Once the leaflets are coapted in the desired arrangement, the fixation device  14  is then detached from the shaft  12  and left behind as an implant to hold the leaflets together in the coapted position. As mentioned previously, the fixation device  14  is coupled to the shaft  12  by a coupling mechanism  17 .  FIGS. 5A-5B ,  6 A- 6 B illustrate exemplary embodiments of such coupling mechanisms.  FIG. 5A  shows an upper shaft  20  and a detachable lower shaft  22  which are interlocked at a joining line or mating surface  24 . The mating surface  24  may have any shape or curvature which will allow or facilitate interlocking and later detachment. A snuggly fitting outer sheath  26  is positioned over the shafts  20 ,  22  to cover the mating surface  24  as shown.  FIG. 5B  illustrates detachment of the lower shaft  22  from the upper shaft  20 . This is achieved by retracting the outer sheath  26 , so that the mating surface  24  is exposed, which allows the shafts  20 ,  22  to separate. 
         [0117]    Similarly,  FIG. 6A  illustrates a tubular upper shaft  28  and a detachable tubular lower shaft  30  which are interlocked at a mating surface  32 . Again, the mating surface  32  may have any shape or curvature which will allow or facilitate interlocking and later detachment. The tubular upper shaft  28  and tubular lower shaft  30  form an outer member having an axial channel. A snuggly fitting rod  34  or inner member is inserted through the tubular shafts  28 , to bridge the mating surface  32  as shown. The rod  34  may also be used to actuate the fixation device, such as actuator rod  64  seen in  FIG. 26  or actuator rod  64   a  illustrated in  FIGS. 28A-28B , described below.  FIG. 6B  illustrates detachment of the lower shaft  30  from the upper shaft  28 . This is achieved by retracting the rod  34  to a position above the mating surface  32  which in turn allows the shafts  28 ,  30  to separate. Other examples of coupling mechanisms are described and illustrated in U.S. Pat. No. 6,752,813 (Attorney Docket No. 020489-000400), and U.S. Patent Publication No. 2009/0163934 (Attorney Docket No. 020489-001470US), the entire contents of each of which are incorporated herein by reference for all purposes. 
         [0118]    In a preferred embodiment, mating surface  24  (or mating surface  32 ) is a sigmoid curve defining a male element and female element on upper shaft  20  (or upper shaft  28 ) which interlock respectively with corresponding female and male elements on lower shaft  22  (or lower shaft  30 ). Typically, the lower shaft is the coupling mechanism  17  of the fixation device  14 . Therefore, the shape of the mating surface selected will preferably provide at least some mating surfaces transverse to the axial axis of the a mechanism  19  to facilitate application of compressive and tensile forces through the coupling mechanism  17  to the fixation device  14 , yet causing minimal interference when the fixation device  14  is to be released from the upper shaft. 
       III. Fixation Device 
       [0119]    A. Introduction and Placement of Fixation Device 
         [0120]    The fixation device  14  is delivered to the valve or the desired tissues with the use of a delivery device. The delivery device may be rigid or flexible depending on the application. For endovascular applications, the delivery device comprises a flexible delivery catheter which will be described in later sections. Typically, however, such a catheter comprises a shaft, having a proximal end and a distal end, and a fixation device releasably attached to its distal end. The shaft is usually elongate and flexible, suitable for intravascular introduction. Alternatively, the delivery device may comprise a shorter and less flexible interventional instrument which may be used for trans-thoracic surgical introduction through the wall of the heart, although some flexibility and a minimal profile will generally be desirable. A fixation device is releasably coupleable with the delivery device as illustrated in  FIG. 3A . The fixation device may have a variety of forms, a few embodiments of which will be described herein. 
         [0121]      FIG. 7  illustrates another embodiment of a fixation device  14 . Here, the fixation device  14  is shown coupled to a shaft  12  to form an interventional tool  10 . The fixation device  14  includes a coupling member  19  and a pair of opposed distal elements  18 . The distal elements  18  comprise elongate arms  53 , each arm having a proximal end  52  rotatably connected to the coupling member  19  and a free end  54 . The free ends  54  have a rounded shape to minimize interference with and trauma to surrounding tissue structures. Preferably, each free end  54  defines a curvature about two axes, one being an axis  66  perpendicular to longitudinal axis of arms  53 . Thus, the engagement surfaces  50  have a cupped or concave shape to surface area in contact with tissue and to assist in grasping and holding the valve leaflets. This further allows arms  53  to nest around the shaft  12  in the closed position to minimize the profile of the device. Preferably, arms  53  are at least partially cupped or curved inwardly about their longitudinal axes  66 . Also, preferably, each free end  54  defines a curvature about an axis  67  perpendicular to axis  66  or the longitudinal axis of arms  53 . This curvature is a reverse curvature along the most distal portion of the free end  54 . Likewise, the longitudinal edges of the free ends  54  may flare outwardly. Both the reverse curvature and flaring minimize trauma to the tissue engaged therewith. 
         [0122]    In a preferred embodiment suitable for mitral valve repair, the transverse width across engagement surfaces  50  (which determines the width of tissue engaged) is at least about 2 mm, usually 3-10 mm, and preferably about 4-6 mm. In some situations, a wider engagement is desired wherein the engagement surfaces  50  are larger, for example about 2 cm, or multiple fixation devices are used adjacent to each other. Arms  53  and engagement surfaces  50  are configured to engage a length of tissue of about 4-10 mm, and preferably about 6-8 mm along the longitudinal axis of arms  53 . Arms  53  further include a plurality of openings to enhance grip and to promote tissue ingrowth following implantation. 
         [0123]    The valve leaflets are grasped between the distal elements  18  and proximal elements  16 . In some embodiments, the proximal elements  16  are flexible, resilient, and cantilevered from coupling member  19 . The proximal elements are preferably resiliently biased toward the distal elements. Each proximal element  16  is shaped and positioned to be at least partially recessed within the concavity of the distal element  18  when no tissue is present. When the fixation device  14  is in the open position, the proximal elements  16  are shaped such that each proximal element  16  is separated from the engagement surface  50  near the proximal end  52  of arm  53  and slopes toward the engagement surface  50  near the free end  54  with the free end of the proximal element contacting engagement surface  50 , as illustrated in  FIG. 7 . This shape of the proximal elements  16  accommodates valve leaflets or other tissues of varying thicknesses. 
         [0124]    Proximal elements  16  include a plurality of openings  63  and scalloped side edges  61  to increase grip on tissue. The proximal elements  16  optionally include frictional accessories, frictional features or grip-enhancing elements to assist in grasping and/or holding the leaflets. In preferred embodiments, the frictional accessories comprise barbs  60  having tapering pointed tips extending toward engagement surfaces  50 . It may be appreciated that any suitable frictional accessories may be used, such as prongs, windings, bands, barbs, grooves, channels, bumps, surface roughening, sintering, high-friction pads, coverings, coatings or a combination of these. Optionally, magnets may be present in the proximal and/or distal elements. It may be appreciated that the mating surfaces will be made from or will include material of opposite magnetic charge to cause attraction by magnetic force. For example, the proximal elements and distal elements may each include magnetic material of opposite charge so that tissue is held under constant compression between the proximal and distal elements to facilitate faster healing and ingrowth of tissue. Also, the magnetic force may be used to draw the proximal elements  16  toward the distal elements  18 , in addition to or alternatively to biasing of the proximal elements toward the distal elements. This may assist in deployment of the proximal elements  16 . In another example, the distal elements  18  each include magnetic material of opposite charge so that tissue positioned between the distal elements  18  is held therebetween by magnetic force. Actuation of the proximal elements may also be accomplished using one or more proximal element lines or actuators such as those described below. 
         [0125]    The proximal elements  16  may be covered with a fabric or other flexible material as described below to enhance grip and tissue ingrowth following implantation. Preferably, when fabrics or coverings are used in combination with barbs or other frictional features, such features will protrude through such fabric or other covering so as to contact any tissue engaged by proximal elements  16 . 
         [0126]    In an exemplary embodiment, proximal elements  16  are formed from metallic sheet of a spring-like material using a stamping operation which creates openings  63 , scalloped edges  61  and barbs  60 . Alternatively, proximal elements  16  could be comprised of a spring-like material or molded from a biocompatible polymer. It should be noted that while some types of frictional accessories that can be used in the present invention may permanently alter or cause some trauma to the tissue engaged thereby, in a preferred embodiment, the frictional accessories will be atraumatic and will not injure or otherwise affect the tissue in a clinically significant way. For example, in the case of barbs  60 , it has been demonstrated that following engagement of mitral valve leaflets by fixation device  14 , should the device later be removed during the procedure barbs  60  leave no significant permanent scarring or other impairment of the leaflet tissue and are thus considered atraumatic. 
         [0127]    The fixation device  14  also includes an actuation mechanism  58 . In this embodiment, the actuation mechanism  58  comprises two link members or legs  68 , each leg  68  having a first end  70  which is rotatably joined with one of the distal elements  18  at a riveted joint  76  and a second end  72  which is rotatably joined with a stud  74 . The legs  68  are preferably comprised of a rigid or semi-rigid metal or polymer such as Elgiloy®, cobalt chromium or stainless steel, however any suitable material may be used. While in the embodiment illustrated both legs  68  are pinned to stud  74  by a single rivet  78 , it may be appreciated, however, that each leg  68  may be individually attached to the stud  74  by a separate rivet or pin. The stud  74  is joinable with an actuator rod  64  (not shown) which extends through the shaft  12  and is axially extendable and retractable to move the stud  74  and therefore the legs  68  which rotate the distal elements  18  between closed, open and inverted positions. Likewise, immobilization of the stud  74  holds the legs  68  in place and therefore holds the distal elements  18  in a desired position. The stud  74  may also be locked in place by a locking feature which will be further described in later sections. 
         [0128]    In any of the embodiments of fixation device  14  disclosed herein, it may be desirable to provide some mobility or flexibility in distal elements  18  and/or proximal elements  16  in the closed position to enable these elements to move or flex with the opening or closing of the valve leaflets. This provides shock absorption and thereby reduces force on the leaflets and minimizes the possibility for tearing or other trauma to the leaflets. Such mobility or flexibility may be provided by using a flexible, resilient metal or polymer of appropriate thickness to construct the distal elements  18 . Also, the locking mechanism of the fixation device (described below) may be constructed of flexible materials to allow some slight movement of the proximal and distal elements even when locked. Further, the distal elements  18  can be connected to the coupling mechanism  19  or to actuation mechanism  58  by a mechanism that biases the distal element into the closed position (inwardly) but permits the arms to open slightly in response to forces exerted by the leaflets. For example, rather than being pinned at a single point, these components may be pinned through a slot that allowed a small amount of translation of the pin in response to forces against the arms. A spring is used to bias the pinned component toward one end of the slot. 
         [0129]      FIGS. 8A-8B ,  9 A- 9 B,  10 A- 10 B,  11 A- 11 B, and  FIGS. 12-14  illustrate embodiments of the fixation device  14  of  FIG. 7  in various possible positions during introduction and placement of the device  14  within the body to perform a therapeutic procedure.  FIG. 8A  illustrates an embodiment of an interventional tool  10  delivered through a catheter  86 . It may be appreciated that the interventional tool  10  may take the form of a catheter, and likewise, the catheter  86  may take the form of a guide catheter or sheath. However, in this example the terms interventional tool  10  and catheter  86  will be used. The interventional tool  10  comprises a fixation device  14  coupled to a shaft  12  and the fixation device  14  is shown in the closed position.  FIG. 8B  illustrates a similar embodiment of the fixation device of  FIG. 8A  in a larger view. In the closed position, the opposed pair of distal elements  18  are positioned so that the engagement surfaces  50  face each other. Each distal element  18  comprises an elongate arm  53  having a cupped or concave shape so that together the arms  53  surround the shaft  12  and optionally contact each other on opposite sides of the shaft. This provides a low profile for the fixation device  14  which is readily passable through the catheter  86  and through any anatomical structures, such as the mitral valve. In addition,  FIG. 8B  further includes an actuation mechanism  58 . In this embodiment, the actuation mechanism  58  comprises two legs  68  which are each movably coupled to a base  69 . The base  69  is joined with an actuator rod  64  which extends through the shaft  12  and is used to manipulate the fixation device  14 . In some embodiments, the actuator rod  64  attaches directly to the actuation mechanism  58 , particularly the base  69 . However, the actuator rod  64  may alternatively attach to a stud  74  which in turn is attached to the base  69 . In some embodiments, the stud  74  is threaded so that the actuator rod  64  attaches to the stud  74  by a screw-type action. However, the rod  64  and stud  74  may be joined by any mechanism which is releasable to allow the fixation device  14  to be detached from shaft  12 . Other aspects of the actuator rod and its coupling with the fixation device are disclosed below. 
         [0130]      FIGS. 9A-9B  illustrate the fixation device  14  in the open position. In the open position, the distal elements  18  are rotated so that the engagement surfaces  50  face a first direction. Distal advancement of the stud  74  relative to coupling member  19  by action of the actuator rod  64  applies force to the distal elements  18  which begin to rotate around joints  76  due to freedom of movement in this direction. Such rotation and movement of the distal elements  18  radially outward causes rotation of the legs  68  about joints  80  so that the legs  68  are directed slightly outwards. The stud  74  may be advanced to any desired distance correlating to a desired separation of the distal elements  18 . In the open position, engagement surfaces  50  are disposed at an acute angle relative to shaft  12 , and are preferably at an angle of between 90 and 180 degrees relative to each other. In one embodiment, in the open position the free ends  54  of arms  53  have a span therebetween of about 10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm. 
         [0131]    Proximal elements  16  are typically biased outwardly toward arms  53 . The proximal elements  16  may be moved inwardly toward the shaft  12  and held against the shaft  12  with the aid of proximal element lines  90  which can be in the form of sutures, wires, nitinol wire, rods, cables, polymeric lines, or other suitable structures. The proximal element lines  90  may be connected with the proximal elements  16  by threading the lines  90  in a variety of ways. When the proximal elements  16  have a loop shape, as shown in  FIG. 9A , the line  90  may pass through the loop and double back. When the proximal elements  16  have an elongate solid shape, as shown in  FIG. 9B , the line  90  may pass through one or more of the openings  63  in the element  16 . Further, a line loop  48  may be present on a proximal element  16 , also illustrated in  FIG. 9B , through which a proximal element line  90  may pass and double back. Such a line loop  48  may be useful to reduce friction on proximal element line  90  or when the proximal elements  16  are solid or devoid of other loops or openings through which the proximal element lines  90  may attach. A proximal element line  90  may attach to the proximal elements  16  by detachable means which would allow a single line  90  to be attached to a proximal element  16  without doubling back and would allow the single line  90  to be detached directly from the proximal element  16  when desired. Examples of such detachable means include hooks, snares, clips or breakable couplings, to name a few. By applying sufficient tension to the proximal element line  90 , the detachable means may be detached from the proximal element  16  such as by breakage of the coupling. Other mechanisms for detachment may also be used. Similarly, a lock line  92  may be attached and detached from a locking mechanism by similar detachable means. 
         [0132]    In the open position, the fixation device  14  can engage the tissue which is to be approximated or treated. The embodiment illustrated in  FIGS. 7-9B  is adapted for repair of the mitral valve using an antegrade approach from the left atrium. The interventional tool  10  is advanced through the mitral valve from the left atrium to the left ventricle. The distal elements  18  are oriented to be perpendicular to the line of coaptation and then positioned so that the engagement surfaces  50  contact the ventricular surface of the valve leaflets, thereby grasping the leaflets. The proximal elements  16  remain on the atrial side of the valve leaflets so that the leaflets lie between the proximal and distal elements. In this embodiment, the proximal elements  16  have frictional accessories, such as barbs  60  which are directed toward the distal elements  18 . However, neither the proximal elements  16  nor the barbs  60  contact the leaflets at this time. 
         [0133]    The interventional tool  10  may be repeatedly manipulated to reposition the fixation device  14  so that the leaflets are properly contacted or grasped at a desired location. Repositioning is achieved with the fixation device in the open position. In some instances, regurgitation may also be checked while the device  14  is in the open position. If regurgitation is not satisfactorily reduced, the device may be repositioned and regurgitation checked again until the desired results are achieved. 
         [0134]    It may also be desired to invert the fixation device  14  to aid in repositioning or removal of the fixation device  14 .  FIGS. 10A-10B  illustrate the fixation device  14  in the inverted position. By further advancement of stud  74  relative to coupling member  19 , the distal elements  18  are further rotated so that the engagement surfaces  50  face outwardly and free ends  54  point distally, with each arm  53  forming an obtuse angle relative to shaft  12 . The angle between arms  53  is preferably in the range of about 270 to 360 degrees. Further advancement of the stud  74  further rotates the distal elements  18  around joints  76 . This rotation and movement of the distal elements  18  radially outward causes rotation of the legs  68  about joints  80  so that the legs  68  are returned toward their initial position, generally parallel to each other. The stud  74  may be advanced to any desired distance correlating to a desired inversion of the distal elements  18 . Preferably, in the fully inverted position, the span between free ends  54  is no more than about 20 mm, usually less than about 16 mm, and preferably about 12-14 mm. In this illustration, the proximal elements  16  remain positioned against the shaft  12  by exerting tension on the proximal element lines  90 . Thus, a relatively large space may be created between the elements  16 ,  18  for repositioning. In addition, the inverted position allows withdrawal of the fixation device  14  through the valve while minimizing trauma to the leaflets. Engagement surfaces  50  provide an atraumatic surface for deflecting tissue as the fixation device is retracted proximally. It should be further noted that barbs  60  are angled slightly in the distal direction (away from the free ends of the proximal elements  16 ), reducing the risk that the barbs will catch on or lacerate tissue as the fixation device is withdrawn. 
         [0135]    Once the fixation device  14  has been positioned in a desired location against the valve leaflets, the leaflets may then be captured between the proximal elements  16  and the distal elements  18 .  FIGS. 11A-11B  illustrate the fixation device  14  in such a position. Here, the proximal elements  16  are lowered toward the engagement surfaces  50  so that the leaflets are held therebetween. In  FIG. 11B , the proximal elements  16  are shown to include barbs  60  which may be used to provide atraumatic gripping of the leaflets. Alternatively, larger, more sharply pointed barbs or other penetration structures may be used to pierce the leaflets to more actively assist in holding them in place. This position is similar to the open position of  FIGS. 9A-9B , however the proximal elements  16  are now lowered toward arms  53  by releasing tension on proximal element lines  90  to compress the leaflet tissue therebetween. At any time, the proximal elements  16  may be raised and the distal elements  18  adjusted or inverted to reposition the fixation device  14 , if regurgitation is not sufficiently reduced. 
         [0136]    After the leaflets have been captured between the proximal and distal elements  16 ,  18  in a desired arrangement, the distal elements  18  may be locked to hold the leaflets in this position or the fixation device  14  may be returned to or toward a closed position. Such locking will be described in a later section.  FIG. 12  illustrates the fixation device  14  in the closed position wherein the leaflets (not shown) are captured and coapted. This is achieved by retraction of the stud  74  proximally relative to coupling member  19  so that the legs  68  of the actuation mechanism  58  apply an upwards force to the distal elements  18  which in turn rotate the distal elements  18  so that the engagement surfaces  50  again face one another. The released proximal elements  16  which are biased outwardly toward distal elements  18  are concurrently urged inwardly by the distal elements  18 . The fixation device  14  may then be locked to hold the leaflets in this closed position as described below. 
         [0137]    As shown in  FIG. 13 , the fixation device  14  may then be released from the shaft  12 . As mentioned, the fixation device  14  is releasably coupleable to the shaft  12  by coupling member  19  (best seen in  FIG. 17 ).  FIG. 13  illustrates the coupling structure, a portion of the shaft  12  to which the coupling member  19  of the fixation device  14  attaches. As shown, the proximal element lines  90  may remain attached to the proximal elements  16  following detachment from shaft  12  to function as a tether to keep the fixation device  14  connected with the catheter  86 . Optionally, a separate tether coupled between shaft  12  and fixation device  14  may be used expressly for this purpose while the proximal element lines  90  are removed. In any case, the repair of the leaflets or tissue may be observed by non-invasive visualization techniques, such as echocardiography, to ensure the desired outcome. If the repair is not desired, the fixation device  14  may be retrieved with the use of the tether or proximal element lines  90  so as to reconnect coupling member  19  with shaft  12 . 
         [0138]    In an exemplary embodiments, proximal element lines  90  are elongated flexible threads, wire, cable, sutures or lines extending through shaft  12 , looped through proximal elements  16 , and extending back through shaft  12  to its proximal end. When detachment is desired, one end of each line may be released at the proximal end of the shaft  12  and the other end pulled to draw the free end of the line distally through shaft  12  and through proximal element  16  thereby releasing the fixation device. 
         [0139]      FIG. 14  illustrates a released fixation device  14  in a closed position. As shown, the coupling member  19  remains separated from the shaft  12  of the interventional tool  10  and the proximal elements  16  are deployed so that tissue (not shown) may reside between the proximal elements  16  and distal elements  18 . 
         [0140]    While the above described embodiments of the invention utilize a push-to-open, pull-to-close mechanism for opening and closing distal elements  18 , it should be understood that a pull-to-open, push-to-close mechanism is equally possible. For example, distal elements  18  may be coupled at their proximal ends to stud  74  rather than to coupling member  19 , and legs  68  may be coupled at their proximal ends to coupling member  19  rather than to stud  74 . In this example, when stud  74  is pushed distally relative to coupling member  19 , distal elements  18  would close, while pulling on stud  74  proximally toward coupling member  19  would open distal elements  18 . 
         [0141]    In some situations, the valve leaflets may fully or partially detach from the fixation device due to poor leaflet insertion between the proximal and distal elements. Evaluation of valve leaflet insertion in the fixation device is therefore performed using standard imaging technology such as echocardiography and fluoroscopy. However, depending on the angle and/or position of the proximal and distal elements relative to the delivery catheter, it can be challenging to assess the depth of valve leaflet insertion into the fixation device, or to differentiate between the leaflets and the proximal and distal elements of the fixation device. Visualization is therefore preferably performed with the distal elements in a more open configuration with the distal elements displaced from one another. However, since many current embodiments of the fixation device only permit the proximal elements to open up to an included angle of about 85°, the distal elements therefore must be closed up to an included angle of between about 45° and preferably 60° in order securely grasp the valve leaflets between the proximal and distal elements. While this configuration helps an operator visualize and differentiate between the valve leaflets and the fixation device, it is preferable to further open up the distal elements to an included angle of greater than 90°, and more preferably to 120° or more. Thus, it would be desirable to modify the proximal elements to open up further. 
         [0142]      FIGS. 15A-15H  illustrate an embodiment of a fixation device similar to the device of  FIGS. 7A-14 , with a major difference being that this embodiment includes a gripper pusher.  FIG. 15A  illustrates fixation device  14  that generally takes the same form as fixation device  14  previously described. In addition to the features previously described, fixation device  14  also includes a gripper pusher  81 . The gripper pusher  81  deflects radially outward resulting in a bowed region  83  that expands outward until the bowed region  83  engages a superior surface of the proximal elements  16 . As the bowed region  83  continues to deflect radially outward, it further pushes on the proximal elements  16  such that the proximal elements are deflected and rotated outward toward the engagement surface of the distal elements  18 . Thus, the proximal elements  16  may be deflected outward further than they normally would, and therefore the valve leaflets may be captured between the proximal and distal elements when the distal elements are disposed in a more open position with a larger included angle therebetween. In preferred embodiments, the included angle between the distal elements is greater than about 90°, preferably greater than about 110°, and more preferably greater than about 120°. In the embodiment of  FIG. 15A , the gripper pusher  81  includes two arms formed from a metal, polymer or other wire-like material. Exemplary materials include cobalt chromium alloy, stainless steel, nitinol, and the like. Polymers may also be used to fabricate the gripper pusher. The gripper pusher  81  may be actuated to bow outwards upon application of an axially oriented compressive force that is generally parallel to the longitudinal axis of the gripper pusher arms. During compression, the gripper pusher bows outward forming bowed region  83 . In other embodiments, the gripper pusher may be a spring which is resiliently biased to bow outward forming bowed region  83 . However, when proximal element lines (not illustrated here) are tensioned to lift the proximal elements  16 , the gripper pusher springs will collapse to a reduced profile. 
         [0143]      FIG. 15B  illustrates the fixation device  14  having a covering for tissue ingrowth that is substantially the same as discussed in  FIGS. 16A-16C  below, and with the gripper pusher  81  expanded such that the proximal elements  16  (also referred to as gripping elements) are in engagement with the distal elements  18  (also referred to as fixation elements). The valve leaflets (not shown for convenience) are pinched therebetween.  FIG. 15C  illustrates the gripper pusher  81  in the collapsed configuration. The bowed region  83  collapses, allowing the proximal elements  16  to retract towards shaft  12 , allowing the valve leaflets (not shown) to be released from the fixation device  14 . The gripper pusher  83  is offset from the proximal elements  16  so that the proximal elements can retract without interfering with the gripper pusher  81 . 
         [0144]      FIG. 15D  highlights the gripper pusher  83  which preferably includes two spring arms  99 . Each arm  99  is formed from wire or machined from a sheet or other stock material and in this embodiment has a rectangular cross-section, although other cross-sections are also contemplated. A distal portion  91  of each arm  99  has a notched region  93  forming a pair of fingers that can engage with a boss or other attachment mechanism on the fixation device. The notch may be released from the boss when the fixation device  14  is detached from the delivery catheter shaft  12 . Additionally, each arm includes two bowed regions, or peaks, including a larger distal bowed region  83 , and a smaller proximal bowed region  95 . The larger bowed region  83  flares outwardly a greater distance so as to engage and push the proximal elements  16  into engagement with the distal elements  18 . When the distal bowed region  83  relaxes and collapses away from the proximal elements  16 , or when collapsed by retraction of the proximal elements, the smaller proximal bowed regions  95  expand radially outward. An attachment ring or coupling collar  97  is adjacent nose  318  (described in greater detail below) and is slidably disposed over the shaft  12  and allows coupling of the gripper arms  99  to the shaft  12 .  FIG. 15E  illustrates the distal bowed region  83  in engagement with the proximal elements  16 , and also illustrates engagement of the notch  93  on the distal portion of each arm  99  with a boss  94  on the fixation device  14 . 
         [0145]    Additional components may be provided to facilitate maintaining the alignment of the gripper pushers  83  relative to the delivery catheter shaft  12 . FIG.  15 E 1  shows a cross-sectional view of the delivery catheter shaft  12  with the gripper pusher  83  and FIG.  15 E 2  shows a side view of the same. As shown in FIGS.  15 E 1  and  15 E 2 , each arm  99  may have a slot  8112  and the delivery catheter shaft  12  may have one or more protrusions  1281  which the slots  8112  straddle to maintain the alignment of the gripper pusher  83  relative to the delivery catheter shaft  12 . The region of the arm  99  having the slot  8112  is wider than the remainder of the arm  99  to accommodate the slot  8112 . The greater width may also allow the arm  99  to be pushed to the side without becoming misaligned relative to the delivery catheter shaft  12 . FIG.  15 E 3  shows a cross-sectional view of the delivery catheter shaft  12  and FIG.  15 E 4  shows a side view of the same. As shown in FIGS.  15 E 3  and  15 E 4 , each arm  99  may have one or more inwardly bowed regions  8212  and the delivery catheter shaft  12  may have one or more troughs  1282  which accommodate the inwardly bowed regions  8212  to maintain the alignment of the gripper pusher  83  relative to the delivery catheter shaft  12 . 
         [0146]      FIG. 15F  illustrates a top view of the gripper pusher  81  having two arms  99 .  FIG. 15F  illustrates that the two arms  99  are offset from one another such that in this exemplary embodiment, angle α is about 160° and angle θ is about 200°, as opposed to positioning the arms 180° apart from one another. Asymmetrically positioning the arms about the shaft creates a larger gap on one side, and allows the proximal elements  16  to avoid colliding with the gripper pusher arms  99  when the proximal elements retract against shaft  12 .  FIG. 15G  is a top view of collar  97 , and  FIG. 15H  is a side view of gripper pusher arm  99 . A cutout  98  on one side of arm  99  creates additional room between arms  99 , thereby also helping to prevent the proximal elements  16  from interfering with the gripper pusher  83  when the proximal elements  16  are retracted. The cutouts are on both arms  99  and face the larger gap represented by angle θ to maximize room for the proximal elements  16 . 
         [0147]    As described above, for example, with reference to  FIGS. 9A and 9B , actuation of the proximal elements  16  may be accomplished by using one or more proximal element lines or actuators  90 . Such actuation can be achieved in various ways. For example, as shown in  FIG. 15I , the proximal element actuators  90 A and  90 B could be threaded through line loops  48 A and  48 B, which are disposed on the radially outward and proximal sides of the proximal elements  16 A and  16 B, respectively. The distal ends of proximal element actuators  90 A and  90 B may comprise closed loops  95 A and  95 B, which encircle the shaft  12  and the coupling member  19  shown in  FIG. 15I  as coupled together. As discussed above, the shaft  12  and the coupling member  19  can be releasably coupled together. To have the closed loops  95 A and  95 B surround shaft  12  and the coupling member  19 , the closed loops  95 A and  95 B are placed over the shaft  12  and/or the coupling member  19  prior to the coupling shaft  12  and the coupling member  19  together. When the closed loops  95 A and  95 B encircle the shaft  12  and the coupling member  19 , the closed loops  95 A and  95 B hold the distal ends of the proximal element actuators  90 A and  90 B in place relative to the shaft  12  and the coupling member  19  and restrict the degree to which the proximal element actuators  90 A and  90 B can be retracted. By being threaded through the line loops  48 A and  48 B, the proximal element actuators  90 A and  90 B are mechanically linked to the proximal elements  16 A and  16 B, respectively. Thus, as shown in  FIG. 15J , when the proximal element actuators  90 A and  90 B are retracted proximally in a direction  96 , they move the proximal elements  16 A and  16 B away from the distal elements  18 A and  18 B, respectively. Similarly, pushing the proximal element actuators  90 A and  90 B distally moves the proximal elements  16 A and  16 B toward the distal elements  18 A and  18 B. 
         [0148]    The proximal element actuators  90 A and  90 B may be moved so that the proximal elements  16 A and  16 B are moved at a variety of angles and distances from the distal elements  18 A and  18 B. And, the degree to which the proximal element actuators  90 A and  90 B are pushed or pulled can be maintained to keep the positions the proximal elements  16 A and  16 B have relative to the distal elements  18 . For example, as shown in  FIG. 15K , the proximal element actuators  90 A and  90 B are pulled proximally and maintained in the position shown so as to maintain the proximal elements  16 A and  16 B in an intermediate position relative to the distal elements  18 . This intermediate position is between the position the proximal elements  16 A and  16 B are biased toward and that in which the proximal elements  16 A and  16 B are fully retracted as in  FIG. 15J . As shown in  FIG. 15N , once the proximal elements  16 A and  16 B are in a desired position, the shaft  12  and the coupling member  19  can be decoupled so that proximal retraction of the proximal element actuators  90 A and/or  90 B decouples the proximal element lines from the proximal elements  16 . Thus, the fixation device  14  can be left in place while the shaft  12 , the proximal element actuators  90 A and  90 B, and other parts can be removed from a site of operation. As shown in  FIGS. 15I through 15O , the fixation device  14  typically includes a covering  100  substantially the same as discussed in  FIGS. 16A-16C  below. 
         [0149]    It may be desirable to provide for independent actuation of the proximal elements  16 A and  16 B. For example, as shown in  FIG. 15L , the proximal element actuator  90 A is proximally retracted and rotates the proximal element  16 A away from the distal element  18 A, while the proximal element actuator  90 B is pushed distally and rotates the proximal element  16 B toward the distal element  18 B. Similarly, as shown in  FIG. 15M , the proximal element actuator  90 A is left alone, allowing the proximal element  16 A to maintain the position it is biased toward, while the proximal element actuator  90 B is proximally retracted, moving the proximal element  16 B away from the distal element  18 B. Providing for the independent actuation of the proximal elements  16 A and  16 B allows leaflets to be independently grasped by the proximal elements  16 A and  16 B and the distal elements  18 A and  18 B. Thus, the fixation device  14  can coapt leaflets more easily and at more optimal locations. For example, as opposed to grasping two leaflets simultaneously, a first leaflet can be grasped at a desired position and the fixation device  14  can then be repositioned so that a second leaflet can be grasped at a more optimal position. Alternatively, leaflets may be still be simultaneously grasped if desired as the independently actuatable proximal element actuators can still be moved simultaneously. Also, after leaflets are grasped, they can be released and the leaflets can be grasped again, for example, if the leaflets are malcoapted at the first grasp. 
         [0150]    Embodiments of the fixation device similar to the devices described above may include both a gripper pusher  81  and independently actuatable proximal elements  16 A and  16 B, as shown for example in  FIG. 15O . Having both a gripper pusher  81  and independently actuatable proximal elements  16 A and  16 B may allow the fixation device to have many of the advantages described above such as to more accurately and more strongly grasp leaflets. 
         [0151]      FIG. 15P  shows the distal end of a proximal element actuator  90 . The proximal element actuator  90  comprises a round section  90 R and a flat section  90 F distal of the round section  90 R. When this proximal element actuator  90  is threaded through a proximal element  16  and coupled to a fixation device  14 , the flatter portion of the flat section may be positioned so that it faces proximal element  16 . As the proximal element actuator  90  is proximally advanced, it will therefore tend to deflect it in the direction toward the proximal element  16  instead of in other directions and push the proximal element. The proximal element actuator  90  further comprises a looped end  95 . As shown in  FIG. 15P , the looped end  95  may comprise a separate loop of wire attached with the distal end of the flat section  90 F at its distal end, for example, with solder  94 . 
         [0152]    The proximal element actuator  90  may also be releaseably coupled to the fixation device  14  in other ways. For example, as shown in  FIGS. 15Q and 15R , the proximal element actuator  90  comprises a spiraled distal section  95 L which is releaseably coupled to the fixation device  14 . The spiraled distal section  95 L is wrapped about the shaft  12  and/or the coupling mechanism  19 . Retracting the proximal element actuator  90  with sufficient force may deform the spiraled distal section  95 L so that it is released from the fixation device  14 . Alternatively or in combination, the spiraled distal section  95 L may comprise a shape memory material such that the spiraled distal section  95 L is straightened upon the application of a sufficient amount of heat, facilitating the proximal retraction of the proximal element actuator  90  away from the fixation device  14 . 
         [0153]    The proximal element actuator  90  may be releaseably coupled to the fixation device  14  by suture. As shown in  FIGS. 15S and 15T , a proximal element actuator  90  is releaseably coupled to the fixation device  14  via a suture knot  95 S. Each proximal actuator  90  may be coupled to the fixation device  14  by a separate suture knot  95 S. Alternatively, a pair of proximal actuators  90  may be coupled to the fixation device  14  by a single suture knot. 
         [0154]    A proximal element actuator  90  may comprise an enlarged section  90 T as shown in  FIGS. 15U and 15V . The diameter of the enlarged section  90 T exceeds the diameter of the opening of the loop line  48 . As the proximal element actuator  90  is retracted, the loop line  48  restricts the proximal movement of the enlarged section  90 T. Thus, a pulling force is exerted on the loop line  48  and proximal element  16 , which facilitates the actuation of a proximal element  16 . The enlarged section  90 T may be a sleeve attached over the proximal element actuator  90 . 
         [0155]    The proximal element actuator  90  may be releaseably coupled to the proximal element  16  at the radially outward ends of the proximal element  16  by an attachment device, for example, as shown in FIGS.  15 W 1  to  15 W 2 . The attachment device may comprise a ring  90 CR as shown in a perspective view in FIG.  15 W 1 , a short clip  90 CC as shown in a perspective view in FIG.  15 W 2 , or a long clip  90 CL as shown in FIGS.  15 W 3  to FIG.  15 W 5 . FIG.  15 W 3  shows a perspective view of the long clip  90 CL attaching the proximal element actuator  90  to a proximal element  16 . FIGS.  15 W 4  and  15 W 5  show a front and side view of the same, respectively. The long clip  90 CL may comprise a pair of legs  90 CLL which traverse the length of the proximal element  16 . As shown in FIG.  15 W 5 , a leg  90 CLL is disposed between two rows of barbs  60 . 
         [0156]    The above described attachment devices may be spring loaded to latch onto or sized to slip fit into the radially outward ends of the proximal element  16 . As the proximal element actuator  90  is retracted, the attachment device continues to be attached to the proximal element  16 . As the proximal element  16  is rotated to be substantially parallel to a shaft  19 , however, further proximal retraction of the proximal element actuator  90  can release the attachment device from the outer end of the proximal element  16 . A mechanical mechanism may be provided to limit the degree to which the proximal element actuator  90  can be proximally retracted so that the attachment device is not detached inadvertently. Instead, detachment will occur only upon retraction of the whole delivery device, including the proximal element actuators  90 , from the fixation device  14 . 
         [0157]    The proximal element actuator  90  may comprise two lines: an actuation line  90 AA and a release line  90 RR, for example, as shown in FIGS.  15 X 1  to  15 X 3 . FIG.  15 X 1  shows a perspective view of an radially outer end of a proximal element  16  having an aperture  48 A. FIG.  15 X 2  shows a cross-sectional view of the same. The actuation line  90 AA has a looped end  90 AAL which is threaded through the aperture  48 A to cross through proximal element  16 . The release line  90 RR is threaded through the portion of the looped end  90 AAL. In FIG.  15 X 3 , the actuation line  90 AA and the release line  90 RR are similarly positioned through loop line  48  of proximal element  16 . While the actuation line  90 AA and the release line  90 RR are positioned in the arrangement shown in FIGS.  15 X 1  to  15 X 3 , retracting the actuation line  90 AA rotates the proximal element  16  relative to a distal element  18  similarly to the embodiments described above. Retracting the release line  90 RR so that it no longer is threaded through the looped end  90 AAL allows the actuation line to be retracted away from the proximal element  16 . 
         [0158]    In many embodiments, the shaft  12  and the coupling member  19  are releaseably coupled together via an L-locking mechanism. For example, as shown in FIG.  15 Y 1 , the proximal element actuator  90  may comprise a round T-shaped end  90 T distal of the flat section  90 F and the shaft  12  may comprise L-shaped ends  12 L. As shown in the perspective view of FIG.  15 Y 2 , the proximal element actuator  90  is releaseably coupled to the coupling member  19  when it and shaft  12  are placed into the channel  19 C of the coupling member  19 . As the shaft  12  is placed through the channel  19 C, the L-shaped ends  12 L are forced inwardly until they reach apertures  19 A. At that point, the L-shaped ends  12 L expand outwardly to fit into the apertures  19 A, thereby locking the shaft  12  in place relative to the coupling member  19 , as shown in cross-sectional view of FIG.  15 Y 3 . The round T-shaped distal end  90 T will typically be placed in the channel  19 C prior to the shaft  12 . As shown in FIG.  15 Y 3 , the round T-shaped distal end  90 T then becomes trapped in the space  19 CA between the channel  19 C and a wider portion of the shaft  12  when the shaft is placed therein. Other L-locking or other locking mechanisms are described in commonly assigned U.S. patent application Ser. No. 12/393,452 entitled “Detachment Mechanism for Implantable Fixation Devices” and filed Feb. 26, 2009, the full contents of which are incorporated herein by reference. 
         [0159]    The round T-shaped end  90 T of the proximal element actuator  90  may also be used to facilitate releaseably coupling the proximal element line  90  to the shaft  12  and coupling member  19  is many other ways. For example, as shown in FIG.  15 Z 1 , the L-shaped end  12 L of the shaft  12  may comprise at least one proximal element line slot  12 S. As shown in FIGS.  15 Z 3  and  15 Z 4 , the T-shape end  90 T of the proximal element actuator  90  is slid into the proximal element line slot  12 L. Then, the shaft  12  is placed into the coupling member  19 , thereby also locking the proximal element line  90  in place. As shown in FIG.  15 Z 5 , removing the shaft  12  from the coupling member  19  allows the proximal element line  90  to be slid out of the proximal element line slot  12 S of L-shaped end  12 L, thereby decoupling the proximal element actuator  90  from both the shaft  12  and the coupling device  19 . 
         [0160]    As shown in FIG.  15 AA 1 , the proximal element actuator  90  may comprise a flat T-shaped end  90 TF. The shaft  12  may further comprise an inner distal covering  1511  surrounding a distal portion of the shaft  12  and an outer distal covering  1521  surrounding the inner distal covering. The inner distal covering  1511  will typically be in a fixed position relative to the shaft  12  while the outer distal covering will be moveable relative to the shaft  12  at a range determined by tabs  1515  of inner distal covering  1511  placed through side channels  1525  of the outer distal covering  1521 . To releaseably couple the proximal element actuator  90  to the shaft  12  and coupling line  19 , the T-shaped end  90 TF is fit into a T-shaped cutout  1513  of inner distal covering  1511 , and when the shaft  12  is placed into the coupling device  19 , the coupling device  19  pushes the outer distal covering  1521  over the inner distal covering  1511  to cover the T-shaped cutout  1513  as well as the T-shaped end  90 TF, as shown in FIG.  15 AA 2 . In some embodiments, the outer distal covering  1521  may be spring loaded against the inner distal cover  1523  so that tend to maintain their relative positions shown in FIG.  15 AA 1 . 
         [0161]    Proximal element actuators  90  may be releaseably coupled to the fixation device  14  in a variety of ways using variations of inner and outer distal collars over the distal portion of shaft  12 , for example, as shown in FIGS.  15 AB 1  to  15 AB 7 . FIG.  15 AB 1  shows an inner distal collar  1511 A having a pair of T-shaped cutouts  1513  and a tab  1514 . FIG.  15 AB 3  shows an outer distal collar  1521 A having a channel  1524 . The channel  1524  guides the inner distal collar  1511 A via its tab  1514  as the inner distal collar  1511 A is slid into the outer distal collar  1521 A, for example as shown in FIGS.  15 AB 3  through  15 AB 5 . As in the embodiment shown in FIGS.  15 AA 1  and  15 AA 2 , to releaseably couple the proximal element actuators  90  to the shaft  12  and coupling member  19 , the T-shaped end  90 TF is fit into a T-shaped cutout  1513  of inner distal collar  1511 S. When the shaft  12  is placed into the coupling device  19 , the coupling member  19  pushes the outer distal collar  1521 S over the inner distal collar  1511 S to cover the T-shaped cutout  1513  as well as the T-shaped end  90 TF, as shown in FIGS.  15 AB 6  and  15 AB 7 . 
         [0162]    As described below, a delivery device or delivery catheter  300  may be used to introduce and position fixation devices as described above. In embodiments of the invention with independently actuatable proximal element lines, the handle  304  of the delivery catheter will typically include control mechanisms for the independently actuable proximal element lines. For example, a control mechanism may comprise a pair of independently actuable proximal element line handles  393 A and  393 B placed in parallel, as shown in FIG.  15 AC 1 , or placed coaxially, as shown in FIG.  15 AC 2 . The proximal element line handles  393 A and  393 B are coupled to proximal element lines  90 A and  90 B and may share a common or interconnecting lumens in the delivery device. Stop may be provided to limit the degree to which the proximal element line handles  393 A and  393 B can be retracted or advanced, thereby limiting the degree to which the proximal element actuators  90 A and  90 B can be retracted or advanced. In some embodiments, for example, as shown by FIGS.  15 AC 3  and  15 AC 4 , a proximal element line handle  393  may be actuated by a rotatable switch 395 attached to it. 
         [0163]    B. Covering on Fixation Device 
         [0164]    The fixation device  14  may optionally include a covering. The covering may assist in grasping the tissue and may later provide a surface for tissue ingrowth. Ingrowth of the surrounding tissues, such as the valve leaflets, provides stability to the device  14  as it is further anchored in place and may cover the device with native tissue thus reducing the possibility of immunologic reactions. The covering may be comprised of any biocompatible material, such as polyethylene terepthalate, polyester, cotton, polyurethane, expanded polytetrafluoroethylene (ePTFE), silicon, or various polymers or fibers and have any suitable form, such as a fabric, mesh, textured weave, felt, looped or porous structure. Generally, the covering has a low profile so as not to interfere with delivery through an introducer sheath or with grasping and coapting of leaflets or tissue. 
         [0165]      FIGS. 16A-16C  illustrate a covering  100  on the fixation device  14  wherein the device  14  is in various positions.  FIG. 16A  shows the covering  100  encapsulating the distal elements  18  and the actuation mechanism  58  while the device  14  is in the open position. Thus, the engagement surfaces  50  are covered by the covering  100  which helps to minimize trauma on tissues and provides additional friction to assist in grasping and retaining tissues.  FIG. 16B  shows the device  14  of  FIG. 16A  in the inverted position. The covering  100  is loosely fitted and/or is flexible or elastic such that the device  14  can freely move to various positions and the covering  100  conforms to the contours of the device  14  and remains securely attached in all positions.  FIG. 16C  shows the device  14  in the closed position. Thus, when the fixation device  14  is left behind as an implant in the closed position, the exposed surfaces of the device  14  are substantially covered by the covering  100 . It may be appreciated that the covering  100  may cover specific parts of the fixation device  14  while leaving other parts exposed. For example, the covering  100  may comprise sleeves that fit over the distal elements  18  and not the actuation mechanism  58 , caps that fit over the distal ends  54  of the distal elements  18  or pads that cover the engagement surfaces  50 , to name a few. It may be appreciated that, the covering  100  may allow any frictional accessories, such as barbs, to be exposed. Also, the covering  100  may cover the proximal elements  16  and/or any other surfaces of the fixation device  14 . In any case, the covering  100  should be durable to withstand multiple introduction cycles and, when implanted within a heart, a lifetime of cardiac cycles. 
         [0166]    The covering  100  may alternatively be comprised of a polymer or other suitable materials dipped, sprayed, coated or otherwise adhered to the surfaces of the fixation device  14 . Optionally, the polymer coating may include pores or contours to assist in grasping the tissue and/or to promote tissue ingrowth. 
         [0167]    Any of the coverings  100  may optionally include drugs, antibiotics, anti-thrombosis agents, or anti-platelet agents such as heparin, COUMADIN® (Warfarin Sodium), to name a few. These agents may, for example, be impregnated in or coated on the coverings  100 . These agents may then be delivered to the grasped tissues surrounding tissues and/or bloodstream for therapeutic effects. 
         [0168]    C. Fixation Device Locking Mechanisms 
         [0169]    As mentioned previously, the fixation device  14  optionally includes a locking mechanism for locking the device  14  in a particular position, such as an open, closed or inverted position or any position therebetween. It may be appreciated that the locking mechanism includes an unlocking mechanism which allows the device to be both locked and unlocked.  FIGS. 17-20  illustrate an embodiment of a locking mechanism  106 . Referring to  FIG. 17 , in this embodiment, the locking mechanism  106  is disposed between the coupling member  19  and the base  69  of the actuation mechanism  58 . The base  69  is fixedly attached to the stud  74  which extends through the locking mechanism  106 . The stud  74  is releasably attached to the actuator rod  64  which passes through the coupling member  19  and the shaft  12  of the interventional tool  10 . The base  69  is also connected to the legs  68  of the actuation mechanism  58  which are in turn connected to the distal elements  18 . 
         [0170]      FIG. 17  also illustrates the proximal elements  16 , which in this embodiment straddle the locking mechanism and join beneath the locking mechanism  106 . The proximal elements  16  are shown supported by proximal element lines  90 . The proximal elements  16  are raised and lowered by manipulation of the proximal element lines  90 . In addition, lock lines  92  are shown connected with a release harness  108  of the locking mechanism  106 . The lock lines  92  are used to lock and unlock the locking mechanism  106  as will be described below. The proximal element lines  90  and lock lines  92  may be comprised of any suitable material, typically wire, nitinol wire, cable, suture or thread, to name a few. In addition, the proximal element lines  90  and/or lock lines  92  may include a coating, such as parylene. Parylene is a vapor deposited pinhole free protective film which is conformal and biocompatible. It is inert and protects against moisture, chemicals, and electrical charge. 
         [0171]      FIG. 18  provides a front view of the locking mechanism  106  of  FIG. 17 . However, here the proximal elements  16  are supported by a single proximal element line  90  which is through both of the proximal elements  16 . In this arrangement both of the elements are raised and lowered simultaneously by action of a single proximal element line  90 . Whether the proximal elements  16  are manipulated individually by separate proximal element lines  90  or jointly by a single proximal element line  90 , the proximal element lines  90  may extend directly through openings in the proximal elements and/or through a layer or portion of a covering  100  on the proximal elements, or through a suture loop above or below a covering  100 . 
         [0172]      FIGS. 19-20  illustrate the locking mechanism  106  showing the locking mechanism  106  in the unlocked and locked positions respectively. Referring to  FIG. 19 , the locking mechanism  106  includes one or more wedging elements, such as rolling elements. In this embodiment, the rolling elements comprise a pair of barbells  110  disposed on opposite sides of the stud  74 , each barbell having a pair of generally cylindrical caps and a shaft therebetween. The barbells  110  and the stud  74  are preferably comprised of cobalt chromium or stainless steel, however any suitable material may be used. The barbells  110  are manipulated by hooked ends  112  of the release harness  108 . When an upwards force is applied to the harness  108  by the lock line  92  (illustrated in  FIG. 17 ), the hooked ends  112  raise the barbells  110  against a spring  114 , as shown in  FIG. 19 . This draws the barbells  110  up along a sidewall or sloping surface  116  which unwedges the barbells  110  from against the stud  74 . In this position, the stud  74  is free to move. Thus, when the lock line  92  raises or lifts the harness  108 , the locking mechanism  106  is in an unlocked position wherein the stud  74  is free to move the actuation mechanism  58  and therefore the distal elements  18  to any desired position. Release of the harness  108  by the lock line  92  transitions the locking mechanism  106  to a locked position, illustrated in  FIG. 20 . By releasing the upwards force on the barbells  110  by the hooked ends  112 , the spring  114  forces the barbells  110  downwards and wedges the barbells  110  between the sloping surface  116  and the stud  74 . This restricts motion of the stud  74 , which in turn locks the actuation mechanism  58  and therefore distal elements  18  in place. In addition, the stud  74  may include one or more grooves  82  or indentations which receive the barbells  110 . This may provide more rapid and positive locking by causing the barbells  110  to settle in a definite position, increase the stability of the locking feature by further preventing movement of the barbells  110 , as well as tangible indication to the user that the barbell has reached a locking position. In addition, the grooves  82  may be used to indicate the relative position of the distal elements  18 , particularly the distance between the distal elements  18 . For example, each groove  82  may be positioned to correspond with a 0.5 or 1.0 mm decrease in distance between the distal elements  18 . As the stud  74  is moved, the barbells  110  will contact the grooves  82 ; by counting the number of grooves  82  that are felt as the stud  74  is moved, the user can determine the distance between the distal elements  18  and can provide the desired degree of coaptation based upon leaflet thickness, geometry, spacing, blood flow dynamics and other factors. Thus, the grooves  82  may provide tactile feedback to the user. 
         [0173]    The locking mechanism  106  allows the fixation device  14  to remain in an unlocked position when attached to the interventional tool  10  during grasping and repositioning and then maintain a locked position when left behind as an implant. It may be appreciated, however, that the locking mechanism  106  may be repeatedly locked and unlocked throughout the placement of the fixation device  14  if desired. Once the final placement is determined, the lock line  92  and proximal element lines  90  are removed and the fixation device is left behind. 
         [0174]      FIGS. 21 ,  22 A- 22 B illustrate another embodiment of a locking mechanism  106 . Referring to  FIG. 21 , in this embodiment, the locking mechanism  106  is again disposed between the coupling member  19  and the base  69  of the actuation mechanism  58 . The base  69  is connected to the stud  74  which extends through the locking mechanism  106 , and connects to an actuator rod which extends through the coupling member  19  and the shaft  12  of the interventional tool  10 . The base  69  is also connected to the legs  68  of the actuation mechanism  58  which are in turn connected to the distal elements  18 .  FIG. 21  also illustrates the proximal elements  16  which manipulate the locking mechanism  106  in this embodiment. The locking mechanism  106  comprises folded leaf structures  124  having overlapping portions  124   a ,  124   b , each folded structure  124  being attached to a proximal element  16 . In  FIG. 21  and  FIG. 22A , the folded structures  124  are shown without the remainder of the locking mechanism  106  for clarity. Proximal elements  16  are flexible and resilient and are biased outwardly. The folded leaf structures  124  include holes  125  ( FIG. 22B ) in each overlapping portion  124   a ,  124   b  so that the stud  74  passes through the holes  125  of the portions  124   a ,  124   b  as shown. The locking mechanism includes slots into which ends  123  of the folded leaf structures  124  are fixed. When the proximal elements  16  are in an undeployed position, as in  FIG. 21 , the folded leaf structures  124  lie substantially perpendicular to the stud  74  so that the holes  125  in each overlapping portion are vertically aligned. This allows the stud  74  to pass freely through the holes and the locking mechanism  106  is considered to be in an unlocked position. 
         [0175]    Deployment of the proximal elements  16 , as shown in  FIG. 22A , tilts the folded leaf structures  124  so as to be disposed in a non-perpendicular orientation relative to the stud  74  and the holes  125  are no longer vertically aligned with one another. In this arrangement, the stud  74  is not free to move due to friction against the holes of the folded leaf structure  124 .  FIG. 22B  provides a larger perspective view of the folded structures  124  in this position. Thus, the locking mechanism  106  is considered to be in a locked position. This arrangement allows the fixation device  14  to maintain an unlocked position during grasping and repositioning and then maintain a locked position when the proximal elements  16  are deployed and the fixation device  14  is left behind as an implant. It may be appreciated, however, that the locking mechanism  106  may be repeatedly locked and unlocked throughout the placement of the fixation device  14  if desired. 
         [0176]      FIGS. 23 ,  24 A- 24 B illustrate another embodiment of a locking mechanism  106 . Referring to  FIG. 22 , in this embodiment, the locking mechanism  106  is again disposed between the coupling member  19  and the base  69  of the actuation mechanism  58 . And, the base  69  is connected to the stud  74  which extends through the locking mechanism  106  and connects to an actuator rod which extends through the coupling member  19  and the shaft of the interventional tool  10 .  FIG. 22  illustrates the proximal elements  16  which manipulate the locking mechanism  106  in this embodiment. The locking mechanism  106  comprises C-shaped structures  128 , each C-shaped structure  128  attached to a proximal element  16 . The C-shaped structures  128  hook around the stud  74  so that the stud  74  passes through the “C” of each structure  128  as shown in  FIGS. 24A-24B . As shown, the structures  128  cross each other and the “C” of each structure  128  faces each other. A spring  130  biases the C-shaped structures into engagement with one another. When the proximal elements are in an undeployed position, as in  FIG. 24A , the C-shaped structures  128  are urged into an orientation more orthogonal to the axial direction defined by stud  74 , thus bringing the “C” of each structure  128  into closer axial alignment. This allows the stud  74  to pass freely through the “C” of each structure  128 . Deployment of the proximal elements  16  outwardly urges the C-shaped structures into a more angular, non-orthogonal orientation relative to stud  74  causing the sidewalls of the “C” of each structure  128  to engage stud  74  more forcefully. In this arrangement, the stud  74  is not free to move due to friction against the “C” shaped structures  128 . 
         [0177]    D. Additional Embodiments of Fixation Devices 
         [0178]    In other embodiments, the proximal elements may be manipulated to enhance gripping. For example, the proximal elements may be lowered to grasp leaflets or tissue between the proximal and distal elements, and then the proximal elements may be moved to drag the leaflets or tissue into the fixation device. In another example, the proximal elements may be independently lowered to grasp the leaflets or tissue. This may be useful for sequential grasping. In sequential grasping, one proximal element is lowered to capture a leaflet or tissue portion between the proximal and distal elements. The fixation device is then moved, adjusted or maneuvered to a position for grasping another leaflet or tissue portion between another set of proximal and distal elements. In this position, the second proximal element is then lowered to grasp this other leaflet or tissue portion. 
         [0179]    Other exemplary embodiments of fixation devices are disclosed in U.S. Pat. No. 7,563,267 (Attorney Docket No. 020489-001400US) and U.S. Pat. No. 7,226,467 (Attorney Docket No. 020489-001700US), the entire contents of each, fully incorporated herein by reference. One of skill in the art will appreciate that the various features of the disclosed fixation devices may be substituted with one another or used in combination with other disclosed features. 
       IV. Delivery Device 
       [0180]    A. Overview of Delivery Device 
         [0181]      FIG. 25  provides a perspective view of an embodiment of a delivery device or delivery catheter  300  which may be used to introduce and position a fixation device as described above. The delivery catheter  300  includes a shaft  302 , having a proximal end  322  and a distal end  324 , and a handle  304  attached to the proximal end  322 . A fixation device (not shown) is removably coupleable to the distal end  324  for delivery to a site within the body, typically for endovascular delivery to the mitral valve. Thus, extending from the distal end  324  is a coupling structure  320  for coupling with a fixation device. Also extending from the distal end  324  is an actuator rod  64 . The actuator rod  64  is connectable with the fixation device and acts to manipulate the fixation device, typically opening and closing the distal elements. Such coupling to a fixation device is illustrated in  FIG. 26 . 
         [0182]      FIG. 26  illustrates an embodiment of a fixation device  14  coupled to the distal end  324  of the delivery catheter  300 . The shaft  302  is shown having a nose  318  near its distal end  324 . In this embodiment, the nose  318  has a flanged shape. Such a flanged shape prevents the nose  318  from being retracted into a guiding catheter or introducer as will be discussed in later sections. However, it may be appreciated that the nose  318  may have any shape including bullet, rounded, blunt or pointed, to name a few. Extending from the nose  318  is a compression coil  326  through which the coupling structure  320  and actuator rod  64  pass. The actuator rod  64  is coupleable, as shown, with the stud  74  of the fixation device  14 . Such coupling is illustrated in  FIG. 27 . 
         [0183]      FIG. 27  illustrates a portion of the shaft  302  of the delivery catheter  300  and a fixation device  14  which is coupleable with the catheter  300 . Passing through the shaft  302  is the actuator rod  64 . In this embodiment, the actuator rod  64  comprises a proximal extremity  303  and a distal extremity  328 , the distal extremity  328  of which is surrounded by a coil  330 . The proximal extremity  303  is typically comprised of stainless steel, nitinol, or Elgiloy®, to name a few, and may have a diameter in the range of 0.010 in. to 0.040 in., preferably 0.020 in. to 0.030 in., more preferably 0.025 in., and a length in the range of 48 to 72 in. The distal extremity  328  may be tapered, is typically comprised of stainless steel, nitinol, or Elgiloy®, to name a few, and may have a diameter in the range of 0.011 to 0.025 in and a length in the range of 4 to 12 in. Such narrowing increases flexibility of the distal end  324  of the actuator rod  64 . The actuator rod  64  further comprises a joiner  332  which is attached to the distal extremity  328 . The joiner  332  is removably attachable with stud  74  of the fixation device  14 . In this embodiment, the joiner  332  has internal threads which mate with external threads on the stud  74  of the fixation device  14 . As described previously, the stud  74  is connected with the distal elements  18  so that advancement and retraction of the stud  74 , by means of the actuator rod  64 , manipulates the distal elements. Likewise, the coupling member  19  of the fixation device  14  mates with the coupling structure  320  of the catheter  300 . Thus, the coupling member  19  and coupling structure  320  function as previously described in relation to  FIGS. 6A-6B . 
         [0184]    Referring back to  FIG. 26 , the fixation device  14  may also include a locking mechanism which includes a release harness  108 , as previously described in relation to  FIGS. 17-20 . Lock lines  92  are connected with the release harness  108  to lock and unlock the locking mechanism  106  as previously described. The lock lines  92  extend through the shaft  302  of the delivery catheter  300  and may connect with the release harness  108  in various arrangements as will be illustrated in later sections. Similarly, proximal element lines  90  extend through the shaft  302  of the delivery catheter  300  and connect with the proximal elements  16 . The proximal elements  16  are raised and lowered by manipulation of the proximal element lines  90  as previously described. The proximal element lines  90  may connect with the proximal elements  16  in various arrangements as will be illustrated in later sections. 
         [0185]    Referring back to  FIG. 25 , the handle  304  attached to the proximal end  322  of the shaft  302  is used to manipulate the coupled fixation device  14  and to optionally decouple the fixation device  14  for permanent implantation. As described, the fixation device  14  is primarily manipulated by the actuator rod  64 , proximal element lines  90  and lock lines  92 . The actuator rod  64  manipulates the distal elements  18 , the proximal element lines  90  manipulate the proximal elements  16  and the lock lines  92  manipulate the locking mechanism. In this embodiment, the actuator rod  64  may be translated (extended or retracted) to manipulate the distal elements  18 . This is achieved with the use of the actuator rod control  314  which will be described in later sections. The actuator rod  64  may also be rotated to engage or disengage the threaded joiner with the threaded stud  74 . This is achieved with the use of the actuator rod handle  316  which will also be described in later sections. Further, the proximal element lines  90  may be extended, retracted, loaded with various amounts of tension or removed with the use of the proximal element line handle  312 . And, the lock lines  92  may be may be extended, retracted, loaded with various amounts of tension or removed with the use of the lock line handle  310 . Both of these handles  310 ,  312  will be described in more detail in later sections. The actuator rod handle  316 , actuator rod control  314 , proximal element line handle  312  and lock line handle  310  are all joined with a main body  308  within which the actuator rod  64 , proximal element lines  90  and lock lines  92  are guided into the shaft  302 . The handle  304  further includes a support base  306  connected with the main body  308 . The main body  308  is slideable along the support base  306  to provide translation of the shaft  302 . Further, the main body  308  is rotateable around the support base  306  to rotate the shaft. 
         [0186]    While the embodiment of  FIG. 27  is promising, in certain situations, the actuator rod  64  may deform, especially along the thinner distal extremity region  328 , during delivery of fixation device  14 , thereby making it more challenging to properly deliver and attach the fixation device to the valve leaflets. For example, when tracking tortuous vessels, or when steering the distal portion of the delivery device through large angles, e.g. 90° or more, the distal tapered extremity  328  of the actuator rod  64  may take a permanent set and thus may fail to return to a substantially straight configuration after being deflected.  FIGS. 28A-28B  illustrate an alternative embodiment of the actuator rod illustrated in  FIG. 27 . In this embodiment, the distal tapered extremity  328  has been replaced with a flexible cable. Actuator rod  64   a  is a long shaft or mandrel that generally takes the same form as actuator rod  64  in  FIG. 27 . A flexible cable  2702  is disposed between a distal end of the actuator rod  64   a , and a proximal end of coupler or joiner  2708 . The flexible cable  2702  allows torque, tension, and compression to be transmitted to the coupler  2708 , while allowing bending and flexing without resulting in the flexible cable taking a set. In this exemplary embodiment, a distal portion of actuator rod  64   a  is joined to a proximal end of the flexible cable  2702  with a sleeve  2704 . The sleeve  2704  has a central channel  2718  extending therethrough for receiving the flexible cable and the actuator rod. The sleeve  2704  may then be crimped, swaged, or otherwise reduced in diameter in order to fixedly attach the two ends together. In alternative embodiments, adhesives, welds, soldering joints, etc. may also be used to join the two ends together. Similarly, a proximal end of the coupler  2708  may include a central channel  2718  that is sized to receive a distal portion of the flexible cable  2702 . In this exemplary embodiment, the coupler is cylindrically shaped with a proximal portion  2716  having a larger diameter than the distal portion  2710 . After the proximal portion  2716  has been crimped or swaged onto the flexible cable, the diameters of the proximal and distal portions of the coupler may be the same, as illustrated in  FIG. 28B . The distal portion of the coupler may include a threaded channel  2712  which may be threadably attached to the fixation device  14 , such as previously described above in  FIGS. 7 and 27 .  FIG. 28B  illustrates the actuator rod  64   a  after it has been coupled with the flexible cable and the coupler by swaging. 
         [0187]    The flexible cable is preferably resiliently biased to return to a substantially straight or linear configuration, even after being bent or deflected by 90° or more. In preferred embodiments, the flexible cable is 25 cm or shorter, preferably 10 cm to 20 cm long, and more preferably 15 to 20 cm long. The flexible cable also has an outer diameter preferably 0.015″ to 0.035″ and more preferably is 0.020″ to 0.030″ and nominally is 0.025″ although one of skill in the art will appreciate that other dimensions may also be used. The actuator rod  64   a  generally takes the same form as actuator rod  64  in  FIG. 27 . The actuator rod  64   a  and flexible cable  2702  are configured to transmit at least 0.74 inch-ounces of torque with a substantially 1:1 torque transmission ratio from the proximal end of the actuator mandrel to the distal end of the flexible cable. This torque is required to threadably disengage the coupler  2708  from the fixation device after the valve has been satisfactorily repaired. Additionally, the actuator rod  64   a  and the flexible cable  2702  are also designed to transmit at least 2.5 pounds of compressive force distally to the fixation device in order to actuate the distal elements thereof. Also, the actuator rod and flexible cable can withstand at least 14.7 pounds of tensile force without substantial stretching or elongation. This force is experienced when actuating the fixation device to close the distal elements. Various metals, polymers, and other materials may be used for the actuator rod, flexible cable, sleeve, and coupler. However, in preferred embodiments, the coupler is fabricated from 17-4 H1150 stainless steel, while the cable comprises 304V stainless steel, and the mandrel is 304 stainless steel with an ultraspring wire temper. 
         [0188]    Various configurations of the flexible cable may be used, such as the cable illustrated in  FIGS. 29A-32B . The flexible cable of  FIG. 29A-32B  is a stranded cable with a reverse wind designed to have a high torque transmission ratio in the counterclockwise direction. This cable includes four layers of wires. The innermost layer  2802  is seen in  FIG. 29A  and includes three wires  2802   a ,  2802   b ,  2802   c  helically wound together.  FIG. 29B  illustrates a cross-section of cable  2802  taken along the line A-A. The next layer  2902  comprises nine additional strands of wire  2904  wrapped around the innermost layer  2802  as illustrated in  FIG. 30A .  FIG. 30B  is a cross-section taken along the line B-B. The next layer  3002  is illustrated in  FIG. 31A , and comprises ten additional strands of wire  3006  wrapped around layer  2902 , and a cross-section taken along line D-D is shown in  FIG. 31B . Finally, the outermost layer  3102  comprises ten more wires  3108  wrapped around layer  3002  as seen in  FIG. 32A , with cross-sectional taken along line D-D in  FIG. 32B . One of skill in the art will appreciate the various strand material characteristics (e.g. diameter, tensile strength, etc.) and winding patterns that may be used. 
         [0189]    An alternative embodiment is illustrated in  FIGS. 33A-37B . This embodiment is similar to that previously described above, with the major difference being that after the cable has been wound, it is drawn thereby altering the surface finish and some of the mechanical characteristics.  FIG. 33A  illustrates the innermost layer  3202  which includes three wires  3204  wound together, as seen in the cross-section of  FIG. 33B  taken along the line A-A.  FIG. 34A  shows the next layer  3302  which includes nine wires  3304  wrapped around the innermost layer  3202 .  FIG. 34B  shows a cross-section taken along line B-B. The next layer  3402  of wires are shown in  FIG. 35A  having ten wires  3404  wrapped around the previous layer  3302 , as illustrated in the cross-section of  FIG. 35B  taken along line C-C. The outermost layer  3502  is shown in  FIG. 36A  and includes another ten wires  3504  wrapped around the previous layer  3402 , with cross-section taken along line D-D in  FIG. 36B . The assembly of four layers of wire are then drawn in order to alter the surface finish of the cable and to alter material properties of the finished cable assembly to a desired value.  FIG. 37A  illustrates the finished cable assembly  3602  with cross-section taken along line E-E in  FIG. 37B . One of skill in the art will appreciate that other cable configurations may be used, and that these are only exemplary embodiments. 
         [0190]    B. Delivery Catheter Shaft 
         [0191]      FIG. 38  illustrates a cross-sectional view of the delivery catheter shaft  302  of  FIG. 25 . In this embodiment, the shaft  302  has a tubular shape with inner lumen  348  and is comprised of a material which provides hoop strength while maintaining flexibility and kink resistance, such as a braided laminated material. Such material may include stainless steel braided or coiled wire embedded in a polymer such as polyurethane, polyester, Pebax, Grilamid TR55, and AESNO to name a few. To provide further support and hoop strength, a support coil  346  is disposed within the lumen  348  of shaft  302  as illustrated in  FIG. 38 . 
         [0192]    Passing through the support coil  346  are a variety of elongated bodies, including tubular guides and cylindrical rods. For example, one type of tubular guide is a compression coil  326  extending through lumen  348  from the proximal end  322  to the distal end  324  of the shaft  302 , and the actuator rod  64  extends through the compression coil  326 . Therefore, the compression coil typically has a length in the range of 48 to 60 in. and an inner diameter in the range of 0.020 to 0.035 in. to allow passage of the actuator rod  64  therethrough. The actuator rod  64  is manipulable to rotate and translate within and relative to the compression coil  326 . The compression coil  326  allows lateral flexibility of the actuator rod  64  and therefore the shaft  302  while resisting buckling and providing column strength under compression. The compression coil may be comprised of 304V stainless steel to provide these properties. 
         [0193]    To provide additional tensile strength for the shaft  302  and to minimize elongation, a tension cable  344  may also pass through the support coil  346 . The tension cable  344  extends through lumen  348  from the proximal end  322  to the distal end  324  of the shaft  302 . Therefore, the tension cable  344  typically has a diameter in the range of 0.005 in. to 0.010 in. and a length in the range of 48 to 60 in. In preferred embodiments, the tension cable  344  is comprised of 304V stainless steel. 
         [0194]    In addition, at least one lock line shaft  341  having a tubular shape may be present having a lock line lumen  340  through which lock lines  92  pass between the lock line handle  310  and the locking mechanism  106 . The lock line shaft  341  extends through lumen  348  from the proximal end  322  to the distal end  324  of the shaft  302 . Therefore, the lock line shaft  341  typically has a length in the range of 48 to 60 in., an inner diameter in the range of 0.016 to 0.030 in., and an outer diameter in the range of 0.018 to 0.034 in. In preferred embodiments, the lock line shaft  341  is comprised of a 304V stainless steel coil however other structures or materials may be used which provide kink resistance and compression strength. 
         [0195]    Similarly, at least one proximal element line shaft  343  having a tubular shape may be present having a proximal element line lumen  342 . Proximal element lines  90  pass through this lumen  342  between the proximal element line handle  312  and the proximal elements  16 . Thus, the proximal element line shaft  343  extends through lumen  348  from the proximal end  322  to the distal end  324  of the shaft  302 . Therefore, the proximal element line shaft  343  typically has a length in the range of 48 to 60 in., an inner diameter in the range of 0.016 to 0.030 in., and an outer diameter in the range of 0.018 to 0.034 in. In preferred embodiments, the proximal element line shaft  343  is comprised of a 304V stainless steel coil however other structures or materials may be used which provide kink resistance and compression strength. 
         [0196]    In this embodiment, the elongated bodies (compression coil  326  enclosed actuator rod  64 , tension cable  344 , lock line shaft  342 , proximal element line shaft  343 ) each “float” freely in inner lumen  348  within the support coil  346  and are fixed only at the proximal end  322  and distal end  324  of shaft  302 . The lumen  348  is typically filled and flushed with heparinized saline during use. Alternatively or in addition, the lumen  348  may be filled with one or more fillers, such as flexible rods, beads, extruded sections, gels or other fluids. Preferably the fillers allow for some lateral movement or deflection of the elongated bodies within lumen  348  but in some cases may restrict such movement. Typically, the elongated bodies are fixed at the proximal and distal ends of the shaft and are free to move laterally and rotationally therebetween. Such freedom of movement of the elongated bodies provides the shaft  302  with an increased flexibility as the elongated bodies self-adjust and reposition during bending and/or torqueing of the shaft  302 . It may be appreciated that the elongated bodies may not be fixed at the proximal and distal ends. The elongated bodies are simply unconstrained relative to the shaft  302  in at least one location so as to be laterally moveable within the lumen  348 . Preferably the elongated bodies are unrestrained in at least a distal portion of the catheter, e.g. 5-15 cm from the distal end  324 , so as to provide maximum flexibility in the distal portion. 
         [0197]    It may be appreciated, however, that alternate shaft  302  designs may also be used. For example, referring to  FIG. 39 , in this embodiment the shaft  302  again has a tubular shape with an inner lumen  348  and a support coil  346  disposed within the lumen  348  of shaft  302 . Filling the inner lumen  348  within the support coil  346  is an extrusion  334  having lumens through which pass a variety of elongated bodies, including the compression coil  326  enclosed actuator rod  64 , tension cable  344 , lock line shafts  342 , and proximal element line shafts  343 , as shown. The support coil  346  and elongated bodies may have the same geometries and be comprised of the same materials as described above in relation to  FIG. 38 . 
         [0198]    Alternatively, as shown in  FIG. 40 , the shaft  302  may include an internal partition  350  to create multiple lumens within the shaft  302 . For example, the partition  350  may have a central lumen  352  for passage of the actuator rod  64 , optionally surrounded by the compression coil  326 . In addition, the partition  350  may also create at least one lock line lumen  340  for passage of a lock line  92  and at least one proximal element line lumen  341  for passage of a proximal element line  90 . Optionally, each of the lumens defined by partition  350  may be lined with a kink-resistant element, such as a coil as in previous embodiments. 
         [0199]      FIGS. 40A-40B  illustrate embodiments of the nose  318  of the shaft  302 . In  FIG. 40A , the nose  318  comprises a tip ring  280  and a lock ring  282 . In preferred embodiments, Epoxy and PEBAX are deposited between the tip ring  280  and the lock ring  282  to bond them together. The lock ring  282  has a geometry to mate with the tip ring  280  to maintain relative alignment between the two.  FIG. 40B  illustrates another embodiment of the nose  318  of the shaft  302 . Here, the tip ring  280  is covered by a soft tip  284  to provide a more atraumatic tip and a smoother transition to the shaft. 
         [0200]    C. Lock Line Arrangements 
         [0201]    As mentioned previously, when lock lines  92  are present, the lines  92  pass through at least one lock line lumen  340  between the lock line handle  310  and the locking mechanism  106 . The lock lines  92  engage the release harnesses  108  of the locking mechanism  106  to lock and unlock the locking mechanism  106  as previously described. The lock lines  92  may engage the release harnesses  108  in various arrangements, examples of which are illustrated in  FIGS. 41A-41C . In each embodiment, two lock line lumens  340  are present within the shaft  302  of the delivery catheter  300  terminating at the nose  318 . The lumens  340  are disposed on alternate sides of the actuator rod  64  so that each lumen  340  is directed toward a release harness  108 . 
         [0202]      FIG. 41A  illustrates an embodiment wherein two lock lines  92 ,  92 ′ pass through a single lock line lumen  340  and are threaded through a release harness  108  on one side of the actuator rod  64  (the actuator rod  64  is shown without surrounding housing such as coupling structure, for clarity). The lock lines  92 ,  92 ′ are then separated so that each lock line passes on an opposite side of the actuator rod  64 . The lock lines  92 ,  92 ′ then pass through the release harness  108 ′ on the opposite side of the actuator rod  64  and continue together passing through a another single lock line lumen  340 ′. This lock line arrangement is the same arrangement illustrated in  FIG. 26 . 
         [0203]      FIG. 41B  illustrates an embodiment wherein one lock line  92  passes through a single lock line lumen  340 , is threaded through a release harness  108  on one side of the actuator rod  64 , and is returned to the lock line lumen  340 . Similarly, another lock line  92 ′ passes through another single lock line lumen  340 ′, is threaded through a different release harness  108 ′ located on the opposite side of the actuator rod  64 , and is returned to the another single lock line lumen  340 ′. 
         [0204]      FIG. 41C  illustrates an embodiment wherein both lock lines  92 ,  92 ′ pass through a single lock line lumen  340 . One lock line  92  is threaded through a release harness  108  on one side of the actuator rod  64  and is then passed through another lock line lumen  340 ′ on the opposite side of the actuator rod  64 . The other lock line  92 ′ is threaded through another release harness  108 ′ on the other side of the actuator rod  64 ′ and is then passed through the another lock line lumen  340 ′ with the previous lock line  92 . 
         [0205]    It may be appreciated that a variety of lock line arrangements may be used and are not limited to the arrangements illustrated and described above. The various arrangements allow the harnesses  108  to be manipulated independently or jointly, allow various amounts of tension to be applied and vary the force required for removal of the lock lines when the fixation device is to be left behind. For example, a single lock line passing through one or two lumens may be connected to both release harnesses for simultaneous application of tension. 
         [0206]    D. Proximal Element Line Arrangements 
         [0207]    As mentioned previously, when proximal element lines  90  are present, the lines  90  pass through at least one proximal element line lumen  342  between the proximal element line handle  312  and at least one proximal element  16 . The proximal element lines  90  engage the proximal elements  16  to raise or lower the element  16  as previously described. The proximal element lines  90  may engage the proximal elements  16  in various arrangements, examples of which are illustrated in  FIGS. 42A-42B . In each embodiment, two proximal element line lumens  342  are present within the shaft  302  of the delivery catheter  300  terminating at the nose  318 . The lumens  342  are disposed on alternate sides of the actuator rod  64  (the actuator rod  64  is shown without surrounding housing such as coupling structure, for clarity) so that each lumen  342  is directed toward a proximal element  16 . 
         [0208]      FIG. 42A  illustrates an embodiment wherein one proximal element line  90  passes through a single proximal element line lumen  342 . The proximal element line  90  is threaded through an eyelet  360  of a proximal element  16  on one side of the actuator rod  64 , passes over the actuator rod  64  and is threaded through an eyelet  360 ′ of another proximal element  16 ′ on the other side of the actuator rod  64 . The proximal element line  90  then passes through another single proximal element line lumen  342 ′. This proximal element line arrangement is the same arrangement illustrated in  FIG. 26 . 
         [0209]      FIG. 42B  illustrates an embodiment wherein one proximal element line  90  passes through a single proximal element line lumen  342 , is threaded through an eyelet  360  of a proximal element  16  on one side of the actuator rod  64 , and is returned to the proximal element line lumen  342 . Similarly, another proximal element line  90 ′ passes through another single proximal element line lumen  342 ′ on the opposite side of the actuator rod  64 , and is returned to the another single proximal element line lumen  342 ′. 
         [0210]    It may be appreciated that a variety of proximal element line arrangements may be used and are not limited to the arrangements illustrated and described above. The various arrangements allow the proximal elements to be manipulated independently or jointly, allow various amounts of tension to be applied and vary the force required for removal of the proximal element lines when the fixation device is to be left behind. For example, a single proximal element line passing through one or two lumens in shaft  302  may be used for simultaneous actuation of both proximal elements. 
         [0211]    E. Main Body of Handle 
         [0212]      FIG. 43  illustrates an embodiment of the handle  304  of the delivery catheter  300 . As mentioned previously, the actuator rod handle  316 , actuator rod control  314 , proximal element line handle  312  and lock line handle  310  are all joined with the main body  318 . The handle  304  further includes a support base  306  connected with the main body  308 . The main body  308  is slideable along the support base  306  to provide translation of the shaft  302  and the main body  308  is rotateable around the support base  306  to rotate the shaft. 
         [0213]      FIG. 44  provides a partial cross-sectional view of the main body  308  of the handle  304  depicted in  FIG. 43 . As shown, the main body  308  includes a sealed chamber  370  within which the actuator rod  64 , proximal element lines  90  and lock lines  92  are guided into the shaft  302 . The sealed chamber  370  is in fluid communication with the inner lumen  348  of shaft  302  and is typically filled with saline and flushed with heparin or heparinized saline. The sealed chamber  370  has a seal  372  along its perimeter to prevent leakage and the introduction of air to the chamber  370 . Any air in the chamber  370  may be bled from the chamber  370  by one or more luers  374  which pass through the main body  308  into the chamber  370  as illustrated in  FIG. 43 . In this embodiment, the handle  304  includes two such luers  374 , one on each side of the main body  308  (second luer symmetrically positioned on backside of main body  308  in  FIG. 43 , hidden from view). Referring now to  FIG. 44 , the sealed chamber  370  also has various additional seals, such as an actuator rod seal  376  which surrounds the actuator rod  64  where the actuator rod  64  enters the sealed chamber  370 , and a shaft seal  378  which surrounds the shaft  302  where the shaft  302  enters the sealed chamber  370 . 
         [0214]    F. Lock Line Handle and Proximal Element Line Handle 
         [0215]    As mentioned previously, the lock lines  92  may be may be extended, retracted, loaded with various amounts of tension or removed using the lock line handle  310 . Likewise, the proximal element lines  90  may be extended, retracted, loaded with various amounts of tension or removed using the proximal element line handle  312 . Both of these handles  310 ,  312  may be similarly designed to manipulate the appropriate lines  90 ,  92  passing therethrough. 
         [0216]      FIG. 45  illustrates an embodiment of a lock line handle  310  having lock lines  92  passing therethrough. The lock line handle  310  has a distal end  384 , a proximal end  382  and an elongate shaft  383  therebetween. The distal end  382  is positionable within the sealed chamber  370  so that the proximal end  382  extends out of the chamber  370 , beyond the main body  308 . The free ends of the lock lines  92  are disposed near the proximal end  382 , passing through the wall of the handle  310  near a threaded nub  390 . The handle  310  further includes a cap  388  which is positionable on the nub  309 . Internal threading with the cap  388  mates with the threading on the threaded nub  390  so that the cap  388  holds the free ends of the lock lines  92  between the cap  388  and the nub  390  and/or other portions of the handle  310  by friction. The lock lines  92  pass through a central lumen (not shown) of the elongate shaft  383 , extend through the sealed chamber  370  (as shown in  FIG. 44 ) and extend through the shaft  302  to the locking mechanism  106 . 
         [0217]    Disposed near the distal end  384  of the handle  310  is at least one wing  392 . In the embodiment of  FIG. 45 , two wings  392  are present, each wing  392  disposed on opposite sides of the elongate shaft  383 . The wings  392  extend radially outwardly and curve proximally so that a portion is parallel to the elongate shaft  383 , as shown. It may be appreciated that the wings  392  may alternatively have the shape of solid or continuous protrusions which extend radially and have a portion which is parallel to the elongate shaft  383 . The wings  392  are used to hold the lock line handle  310  in a desired position which in turn holds the lock under a desired load of tension, as will be described further below. The handle  310  also includes a finger grip  386  near the proximal end  382  which extends radially outwardly in alignment with the radial extension of the at least one wing  392 . Thus, the user may determine the orientation of the wings  392  within the sealed chamber  370  from the orientation of the finger grip  386  outside of the main body  308 . The finger grip  386  may also serve an ergonomic purpose to assist in manipulating the handle  310 . 
         [0218]    The portion of the wings  392  parallel to the elongate shaft  383  have grooves or serrations  394 . The serrations  394  are used to apply tension to the lock lines  92 . As shown in  FIG. 45A , the lock line handle  310  is positioned within a semi-tube  400  which is disposed within the sealed chamber  370 . The semi-tube  400  comprises a top half  402  and a bottom half  404 , each half  402 ,  404  having grooves or serrations  406  which mate with the serrations  394  of the wings  392 . Thus, when the wings  392  are rotated to mate the serrations  394 ,  406 , as shown in  FIG. 46A , the elongate shaft  383  is held in place. Likewise, the wings  392  may be rotated, as shown in  FIG. 46B , so that the wings  392  are disposed between the halves  402 ,  404  and the serrations  394 ,  406  are disengaged. In this position, the shaft  383  may be translated to apply or release tension in the lock lines  92 . Thus, tension in the lines  92  may be adjusted by rotating the shaft  383  to disengage the serrations  394 ,  406 , translating the shaft  383  and then rotating the shaft  383  back to reengage the serrations  394 ,  406 . Alternatively, the finger grip  386  may be pulled to apply tension to the lock lines  92 . Pulling the finger grip  386  translates the lock line handle  310  within the semi-tube  400 . Such translation is achievable due to angling of the serrations  394 ,  406  and flexibility of wings  382 . However, the angling of the serrations  394 ,  406  prevents translation in the opposite direction, i.e. by pushing the finger grip  386 . Therefore, to release tension from the lock lines  92 , the shaft  383  is rotated to disengage the serrations  394 ,  406 , allowing translation of the shaft  383 , and then the shaft  383  is rotated back to reengage the serrations  394 ,  406 . 
         [0219]    To remove the lock lines  92 , the cap  388  is removed from the threaded nub  390  exposing the free ends of the lock lines  92 . If one lock line  92  is present having two free ends, continuous pulling on one of the free ends draws the entire length of lock line  92  out of the catheter  300 . If more than one lock line  92  is present, each lock line  92  will have two free ends. Continuous pulling on one of the free ends of each lock line  92  draws the entire length of each lock line  92  out of the catheter  300 . 
         [0220]    It may be appreciated that the proximal element line handle  312  has corresponding features to the lock line handle  310  and operates in the same manner as illustrated in  FIGS. 45A ,  46 A- 46 B. It may also be appreciated that other mechanisms may be used for manipulating the lock lines  92  and proximal element lines  90 , such as including buttons, springs, levers and knobs. 
         [0221]    G. Actuator Rod Control and Handle 
         [0222]    The actuator rod  64  may be manipulated using the actuator rod control  314  and the actuator rod handle  316 .  FIG. 47  provides a cross-sectional view of a portion of the handle  304  which includes the actuator rod control  314  and the actuator rod handle  316 . The actuator rod handle  316  is located at the proximal end of the handle  314 . The actuator rod handle  316  is fixedly attached to the proximal end of the actuator rod  64 . The actuator rod  64  is inserted through a collet  426  which is disposed within a holder  428  as shown. The holder  428  has external threads  434  which mate with internal threads  432  of the actuator rod control  314 . Thus, rotation of the actuator rod control  314  causes the holder  428  to translate along the actuator rod control  314  by action of the threading, as will be described in more detail below. The actuator rod control  314  is rotatably coupled with the main body  308  of the handle  304  and is held in place by a lip  430 . 
         [0223]    Referring to  FIG. 47A , the actuator rod control  314  may be manually rotated in a clockwise or counter clockwise direction, as indicated by arrow  436 . Rotation of the actuator rod control  314  translates (extends or retracts) the actuator rod  64  to manipulate the distal elements  18  of the fixation device  14 . Specifically, rotation of the actuator rod control  314  causes the external threads  434  of the adjacent holder  428  to translate along the mated internal threads  432  of the actuator rod control  314 . Rotation of the holder  428  itself is prevented by holding pins  424  which protrude from the holder  428  and nest into grooves  438  in the main body  308  of the handle  304 . As the holder  428  translates, each holding pin  424  translates along its corresponding groove  438 . Since the collet  426  is attached to the holder  428 , the collet  426  translates along with the holder  428 . To simultaneously translate the actuator rod  64 , the actuator rod  64  is removably attached to the collet  426  by a pin  422 . The pin  422  may have any suitable form, including a clip-shape which partially wraps around the collet  426  as illustrated in  FIG. 47 . Thus, rotation of the actuator rod control  314  provides fine control of translation of the actuator rod  64  and therefore fine control of positioning the distal elements  18 . 
         [0224]    Referring to  FIG. 47B , removal of the pin  422 , as shown, allows disengagement of the actuator rod handle  316  and fixedly attached actuator rod  64  from the collet  426 . Once disengaged, the actuator rod  64  may be rotated, as indicated by arrow  440 , by manually rotating the actuator rod handle  316 . As described previously, rotation of the actuator rod  64  engages or disengages the threaded joiner  332  of the delivery catheter  300  from the threaded stud  74  of the fixation device  14 . This is used to attach or detach the fixation device  14  from the delivery catheter  300 . In addition, when the actuator rod  64  is in the disengaged state, the actuator rod  64  may optionally be retracted and optionally removed from the catheter  300  by pulling the actuator rod handle  316  and withdrawing the actuator rod  64  from the handle  304 . 
         [0225]    Depending on the application, the location of the target site, and the approach selected, the devices of the invention may be modified in ways well known to those of skill in the art or used in conjunction with other devices that are known in the art. For example, the delivery catheter may be modified in length, stiffness, shape and steerability for a desired application Likewise, the orientation of the fixation device relative to the delivery catheter may be reversed or otherwise changed. The actuation mechanisms may be changed to be driven in alternate directions (push to open, pull to close, or pull to open, push to close). Materials and designs may be changed to be, for example, more flexible or more rigid. And the fixation device components may be altered to those of different size or shape. Further, the delivery catheter of the present invention may be used to deliver other types of devices, particularly endovascular and minimally invasive surgical devices used in angioplasty, atherectomy, stent-delivery, embolic filtration and removal, septal defect repair, tissue approximation and repair, vascular clamping and ligation, suturing, aneurysm repair, vascular occlusion, and electrophysiological mapping and ablation, to name a few. Thus, the delivery catheter of the present invention may be used for applications in which a highly flexible, kink-resistant device is desirable with high compressive, tensile and torsional strength. 
         [0226]    H. Pusher Handle Design 
         [0227]    After engaging successfully grasping the leaflets, usually at an angle between 120 and 180 degrees, the actuator rod  64  is manually rotated to manipulate the distal elements of the fixation device. This moves the distal elements proximally to an angle, such as 60 degrees as shown in  FIG. 11B . However, with reference to  FIG. 15B , the gripper pusher  81  and the proximal element actuators  90  also need to be retracted as angle between the distal elements  18  is reduced.  FIG. 70  shows an embodiment of a handle that coordinates these movements. As shown in the figure, the proximal element line handle  312  of  FIG. 44  is fitted with a spring loaded pusher attachment  414  that is connected to a gripper pusher actuator  411  that extends to the gripper pusher  81  of the fixation device. This spring loaded pusher attachment  414  surrounds, but moves independently of the proximal element line  90 . The spring  413  functions to provide a tension on the proximal element line  90  by exerting a small force on the gripper pusher  81  relative to the gripper pusher actuator. Further, a gripper pusher actuator wire  412  is coupled to the actuator rod  64  so that when the actuator rod  64  is actuated to close the distal elements  18 , the gripper pusher  81  is retracted. As shown in  FIG. 70 , the pusher actuator wire  412  interacts with the spring loaded pusher attachment  414  to retract the spring loaded pusher attachment  414  when the distal elements  18  are closed. On the other hand, the distal end of the pusher actuator wire  412  is configured to slide distally with respect to the spring loaded pusher attachment  414  so that the distal movement of the gripper pusher  81  is independent of the movement of the distal elements  18 . This permits separation between the proximal elements  16  and the distal elements  18  to aid in grasping leaflets. Lastly, due to the spring coupling between the spring loaded pusher attachment  414  and the proximal element line handle  312 , the proximal element actuator  90  is also retracted in combination with the retracting of the gripper pusher actuator  411 . Notably, due to the spring coupling via the spring  413 , the proximal element actuator  90  is permitted further travel than the gripper pusher actuator  411 . This additional travel is permitted via expansion of the spring  413  and functions to remove slack in the proximal element actuator as the angle between the proximal elements  16  and the distal elements  18  is reduced. 
       V. Multi-Catheter Guiding System 
       [0228]    A. Overview of Guiding System 
         [0229]    Referring to  FIG. 48 , an embodiment of a multi-catheter guiding system 1 of the present invention is illustrated. The system 1 comprises an outer guide catheter  1000 , having a proximal end  1014 , a distal end  1016 , and a central lumen  1018  therethrough, and an inner guide catheter  1020 , having a proximal end  1024 , distal end  1026  and central lumen  1028  therethrough, wherein the inner guide catheter  1020  is positioned coaxially within the central lumen  1018  of the outer guide catheter  1000 , as shown. The distal ends  1016 ,  1026  of catheters  1000 ,  1020 , respectively, are sized to be passable to a body cavity, typically through a body lumen such as a vascular lumen. Thus, the distal end  1016  preferably has an outer diameter in the range of approximately 0.040 in. to 0.500 in., more preferably in the range of 0.130 in. to 0.320 in. The central lumen  1018  is sized for the passage of the inner guide catheter  1020 ; the distal end  1026  preferably has an outer diameter in the range of approximately 0.035 in. to 0.280 in., more preferably 0.120 in to 0.200 in. The central lumen  1028  is sized for the passage of a variety of devices therethrough. Therefore, the central lumen  1028  preferably has an inner diameter in the range of approximately 0.026 in. to 0.450 in., more preferably in the range of 0.100 in. to 0.180 in. 
         [0230]      FIG. 48  illustrates an interventional catheter  1030  positioned within the inner guide catheter  1020  which may optionally be included in system 1, however other interventional devices may be used. The interventional catheter  1030  has a proximal end  1034  and a distal end  1036 , wherein an interventional tool  1040  is positioned at the distal end  1036 . In this embodiment, the interventional tool  1040  comprises a detachable fixation device or clip. Optionally, the interventional catheter  1030  may also include a nosepiece  1042  having a stop  1043 , as shown. The stop  1043  prevents the interventional tool  1040  from entering the central lumen  1028  of the inner guide catheter  1020 . Thus, the interventional catheter  1030  may be advanced and retracted until the stop  1043  contacts the distal end  1026  of the inner guiding catheter  1020  preventing further retraction. This may provide certain advantages during some procedures. It may be appreciated that in embodiments which include such a stop  1043 , the interventional catheter  1030  would be pre-loaded within the inner guide catheter  1020  for advancement through the outer guiding catheter  1000  or both the interventional catheter  1030  and the inner guiding catheter  1020  would be pre-loaded into the outer guiding catheter  1000  for advancement to the target tissue. This is because the stop  1043  prevents advancement of the interventional catheter  1030  through the inner guiding catheter  1020 . 
         [0231]    The outer guide catheter  1000  and/or the inner guide catheter  1020  are precurved and/or have steering mechanisms, embodiments of which will be described later in detail, to position the distal ends  1016 ,  1026  in desired directions. Precurvature or steering of the outer guide catheter  1000  directs the distal end  1016  in a first direction to create a primary curve while precurvature and/or steering of the inner guide catheter  1020  directs distal end  1026  in a second direction, differing from the first, to create a secondary curve. Together, the primary and secondary curves form a compound curve. Advancement of the interventional catheter  1030  through the coaxial guide catheters  1000 ,  1020  guides the interventional catheter  1030  through the compound curve toward a desired direction, usually in a direction which will allow the interventional catheter  1030  to reach its target. 
         [0232]    Steering of the outer guide catheter  1000  and inner guide catheter  1020  may be achieved by actuation of one or more steering mechanisms. Actuation of the steering mechanisms is achieved with the use of actuators which are typically located on handles connected with each of the catheters  1000 ,  1020 . As illustrated in  FIG. 48 , handle  1056  is connected to the proximal end  1014  of the outer guide catheter  1000  and remains outside of the patient&#39;s body during use. Handle  1056  includes steering actuator  1050  which may be used to bend, arc or reshape the outer guide catheter  1000 , such as to form a primary curve. Handle  1057  is connected to the proximal end (not shown) of the inner guide catheter  1020  and may optionally join with handle  1056  to form one larger handle, as shown. Handle  1057  includes steering actuator  1052  which may be used to bend, arc or reshape the inner guide catheter  1020 , such as to form a secondary curve and move the distal end  1026  of the inner guide catheter  1020  through an angle theta, as will be described in a later section. 
         [0233]    In addition, locking actuators  1058 ,  1060  may be used to actuate locking mechanisms to lock the catheters  1000 ,  1020  in a particular position. Actuators  1050 ,  1052 ,  1058 ,  1060  are illustrated as buttons, however it may be appreciated that these and any additional actuators located on the handles  1056 ,  1057  may have any suitable form including knobs, thumbwheels, levers, switches, toggles, sensors or other devices. Other embodiments of the handles will be described in detail in a later section. 
         [0234]    In addition, the handle  1056  may include a numerical or graphical display  1061  of information such as data indicating the position the catheters  1000 ,  1020 , or force on actuators. It may also be appreciated that actuators  1050 ,  1052 ,  1058 ,  1060  and any other buttons or screens may be disposed on a single handle which connects with both the catheters  1000 ,  1020 . 
         [0235]    B. Example Positions 
         [0236]      FIGS. 49A-49D  illustrate examples of positions that the catheters  1000 ,  1020  may hold. Referring to  FIG. 49A , the outer guide catheter  1000  may be precurved and/or steered into a position which includes a primary curve  1100 . The primary curve  1100  typically has a radius of curvature  1102  in the range of approximately 0.125 in. to 1.000 in., preferably in the range of approximately 0.250 in. to 0.500 in. or forms a curve in the range of approximately 0° to 120°. As shown, when the position includes only a primary curve  1100 , the distal end  16  lies in a single plane X. An axis x, transversing through the center of the central lumen  18  at the distal end  16 , lies within plane X. 
         [0237]    Referring to  FIG. 49B , the inner guide catheter  1020  extends through the central lumen  1018  of the outer guide catheter  1000 . The inner guide catheter  1020  may be precurved and/or steered into a position which includes a secondary curve  1104 . The secondary curve  1104  typically has a radius of curvature  10600  in the range of approximately 0.050 in. to 0.750 in., preferably in the range of approximately 0.125 in. to 0.250 in. or forms a curve in the range of approximately 0° to 180°. The secondary curve  1104  can lie in the same plane as the primary curve  1100 , plane X, or it can lie in a different plane, such as plane Z as shown. In this example, plane Z is substantially orthogonal to plane X. Axis z, transversing through the center of the central lumen  1028  of the inner guide catheter  1020  at the distal end  1026 , lies within plane Z. In this example, axis x and axis z are at substantially 90 degree angles to each other; however, it may be appreciated that axis x and axis z may be at any angle in relation to each other. Also, although in this example the primary curve  1100  and the secondary curve  1104  lie in different planes, particularly in substantially orthogonal planes, the curves  1100 ,  1104  may alternatively lie in the same plane. 
         [0238]    Referring now to  FIG. 49C , the inner guide catheter  1020  may be further manipulated to allow the distal end  1026  to move through an angle theta  1070 . The angle theta  1070  is in the range of approximately −180° to +180°, typically in the range of −90° to +90°, possibly in the range of −60° to +60°, −45° to +45°, −30° to +30° or less. As shown, the angle theta  1070  lies within a plane Y. In particular, axis y, which runs through the center of the central lumen  1028  at the distal end  1026 , forms the angle theta  1070  with axis z. In this example, plane Y is orthogonal to both plane X and plane Z. Axes x, y, z all intercept at a point within the central lumen  1028  which also coincides with the intersection of planes X, Y, Z. 
         [0239]    Similarly,  FIG. 49D  illustrates movement of the distal end  1026  through an angle theta  1070  on the opposite side of axis z. Again, the angle theta  1070  is measured from the axis z to the axis y, which runs through the center of the central lumen  1016  at the distal end  1026 . As shown, the angle theta  1070  lies in plane Y. Thus, the primary curve  1100 , secondary curve  1104 , and angle theta  1070  can all lie in different planes, and optionally in orthogonal planes. However, it may be appreciated that the planes within which the primary curve  1100 , secondary curve  1104  and angle theta  1070  lie may be mutually dependent and therefore would allow the possibility that some of these lie within the same plane. 
         [0240]    In addition, the outer guide catheter  1000  may be pre-formed and/or steerable to provide additional curves or shapes. For example, as illustrated in  FIG. 50A , an additional curve  1110  may be formed by the outer guide catheter  1000  proximal to the primary curve  1100 . In this example, the curve  1110  provides lift or raises the distal end  1016  of the outer guide catheter  1000 , which in turn raises the distal end  1026  of the inner guide catheter  1020 . Such lifting is illustrated in  FIG. 50B . Here, the system 1 is shown prior to lifting in dashed line wherein the axis y′ passes through the intersection of axis z and axis x′. After application of curve  1110 , the distal portion of the system 1 is lifted in the direction of axis z so that axis x′ is raised to axis x″ and axis y′ is raised to axis y″. This raises distal end  1026  to a desired height. 
         [0241]    The articulated position of the multi-catheter guiding system 1 illustrated in  FIGS. 49A-49D  and  FIGS. 50A-50B  is particularly useful for accessing the mitral valve.  FIGS. 51A-51D  illustrate a method of using the system 1 for accessing the mitral valve MV. To gain access to the mitral valve, the outer guide catheter  1000  may be tracked over a dilator and guidewire from a puncture in the femoral vein, through the inferior vena cava and into the right atrium. As shown in  FIG. 51A , the outer guide catheter  1000  may be punctured through a fossa F in the interatrial septum S. The outer guide catheter  1000  is then advanced through the fossa F and curved by the primary curve  1100  so that the distal end  1016  is directed over the mitral valve MV. Again, it may be appreciated that this approach serves merely as an example and other approaches may be used, such as through the jugular vein, femoral artery, port access or direct access, to name a few. Positioning of the distal end  1016  over the mitral valve MV may be accomplished by precurvature of the outer guide catheter  1000 , wherein the catheter  1000  assumes this position when the dilator and guidewire are retracted, and/or by steering of the outer guide catheter  1000  to the desired position. In this example, formation of the primary curve  1100  moves the distal end  1016  within a primary plane, corresponding to previous plane X, substantially parallel to the valve surface. This moves the distal end  1016  laterally along the short axis of the mitral valve MV, and allows the distal end  1016  to be centered over the opening O between the leaflets LF. 
         [0242]    Referring to  FIG. 51B , the inner guide catheter  1020  is advanced through the central lumen  1018  of the outer guide catheter  1000  and the distal end  1026  is positioned so that the central lumen  1028  is directed toward the target tissue, the mitral valve MV. In particular, the central lumen  1028  is to be directed toward a specific area of the mitral valve MV, such as toward the opening O between the valve leaflets LF, so that a particular interventional procedure may be performed. In  FIG. 51B , the inner guide catheter  1020  is shown in a position which includes a secondary curve  1104  in a secondary plane, corresponding to previous plane Z. Formation of the secondary curve  1104  moves the distal end  1026  vertically and angularly between the commissures C, directing the central lumen  1028  toward the mitral valve MV. In this position an interventional device or catheter  1030  which is passed through the central lumen  1028  would be directed toward and/or through the opening O. Although the primary curve  1100  and the secondary curve  1104  may be varied to accommodate different anatomical variations of the valve MV and different surgical procedures, further adjustment may be desired beyond these two curvatures for proper positioning of the system 1. 
         [0243]    Referring to  FIG. 51C , the distal end  1026  of the inner guide catheter  1020  may be positioned through an angle theta  1070 . This moves the distal end  1026  vertically and angularly through a theta plane, corresponding to previous plane Y. Movement of the distal end  1026  through the angle theta  1070  in either direction is shown in dashed line in  FIG. 51C . Such movement can be achieved by precurvature and/or by steering of the catheter  1020 . Consequently, the central lumen  1028  can be directed toward the mitral valve MV within a plane which differs from the secondary plane. After such movements, the inner guide catheter  1020  will be in a position so that the opening of the central lumen  1028  at the end  1016  faces the desired direction. In this case, the desired direction is toward the center of and orthogonal to the mitral valve. 
         [0244]    In some instances, it is desired to raise or lower the distal end  1026  so that it is at a desired height in relation to the mitral valve MV. This may be accomplished by precurvature and/or by steering of the outer guide catheter  1000  to form additional curve  1110 . Generally this is used to lift the distal end  1026  above the mitral MV wherein such lifting was illustrated in  FIG. 50B . 
         [0245]    When the curvatures in the catheters  1000 ,  1020  are formed by steering mechanisms, the steering mechanisms may be locked in place by a locking feature. Locking can provide additional stiffness and stability in the guiding system 1 for the passage of interventional devices or catheters  1030  therethrough, as illustrated in  FIG. 48 . The interventional catheter  1030  can be passed through the central lumen  1028  toward the target tissue, in this case the mitral valve MV. Positioning of the distal end  1026  over the opening O, as described above, allows the catheter  1030  to pass through the opening O between the leaflets LF if desired, as shown in  FIG. 51D . At this point, any desired procedure may be applied to the mitral valve for correction of regurgitation or any other disorder. 
         [0246]    C. Steering Mechanisms 
         [0247]    As described previously, the curvatures may be formed in the catheters  1000 ,  1020  by precurving, steering or any suitable means. Precurving involves setting a specific curvature in the catheter prior to usage, such as by heat setting a polymer or by utilizing a shape-memory alloy. Since the catheters are generally flexible, loading of the catheter on a guidewire, dilator obturator or other introductory device straightens the catheter throughout the curved region. Once the catheter is positioned in the anatomy, the introductory device is removed and the catheter is allowed to relax back into the precurved setting. 
         [0248]    To provide a higher degree of control and variety of possible curvatures, steering mechanisms may be used to create the curvatures and position the catheters. In some embodiments, the steering mechanisms comprise cables or pullwires within the wall of the catheter. As shown in  FIG. 52A , the outer guide catheter  1000  may include a pullwire  1120  slidably disposed in lumens within the wall of the catheter  1000  extending to the distal end  1016 . By applying tension to the pullwire  1120  in the proximal direction, the distal end  1016  curves in the direction of the pullwire  1120  as illustrated by arrow  1122 . Likewise, as shown in  FIG. 52B , placement of the pullwire  1120  along the opposite side of the catheter  1000  will allow the distal end  1016  to curve in the opposite direction, as illustrated by arrow  1124 , when tension is applied to the pullwire  1120 . Thus, referring to  FIG. 52C , diametrically opposing placement of pullwires  1120  within the walls of the catheter  1000  allows the distal end  1016  to be steered in opposite directions. This provides a means of correcting or adjusting a curvature. For example, if tension is applied to one pullwire to create a curvature, the curvature may be lessened by applying tension to the diametrically opposite pullwire. Referring now to  FIG. 52D , an additional set of opposing pullwires  1120 ′ may extend within the wall of the catheter  1000  as shown. This combination of pullwires  1120 ,  1120 ′ allows curvature of the distal end in at least four directions illustrated by arrows  1122 ,  1124 ,  1126 ,  1128 . In this example, pullwires  1120  create the primary curve  1100  of the outer guide catheter  1000  and the pullwires  1120 ′ create the lift. It may be appreciated that  FIGS. 52A-52D  also pertain to the inner guide catheter  1020 . For example, in  FIG. 52D , pullwires  1120  may create the secondary curve  1104  of the inner guide catheter  1020  and the pullwires  1120 ′ create the angle theta  1070 . 
         [0249]    Such pullwires  1120  and/or pullwires  1120 ′ and associated lumens may be placed in any arrangement, singly or in pairs, symmetrically or nonsymmetrically and any number of pullwires may be present. This may allow curvature in any direction and about various axes. The pullwires  1120 ,  1120 ′ may be fixed at any location along the length of the catheter by any suitable method, such as gluing, tying, soldering, or potting, to name a few. When tension is applied to the pullwire, the curvature forms from the point of attachment of the pullwire toward the proximal direction. Therefore, curvatures may be formed throughout the length of the catheter depending upon the locations of the points of attachment of the pullwires. Typically, however, the pullwires will be attached near the distal end of the catheter, optionally to an embedded tip ring  280 , illustrated in  FIG. 52E . As shown, the pullwire  1120  passes through an orifice  286  in the tip ring  280 , forms a loop shape and then passes back through the orifice  286  and travels back up through the catheter wall (not shown). In addition, the lumens which house the pullwires may be straight, as shown in  FIGS. 52A-52D , or may be curved. 
         [0250]    D. Catheter Construction 
         [0251]    The outer guide catheter  1000  and inner guide catheter  1020  may have the same or different construction which may include any suitable material or combination of materials to create the above described curvatures. For clarity, the examples provided will be in reference to the outer guide catheter  1000 , however it may be appreciated that such examples may also apply to the inner guide catheter  1020 . 
         [0252]    In embodiments in which the catheter is precurved rather than steerable or in addition to being steerable, the catheter  1000  may be comprised of a polymer or copolymer which is able to be set in a desired curvature, such as by heat setting Likewise, the catheter  1000  may be comprised of a shape-memory alloy. 
         [0253]    In embodiments in which the catheter is steerable, the catheter  1000  may be comprised of one or more of a variety of materials, either along the length of the catheter  1000  or in various segments. Example materials include polyurethane, Pebax, nylon, polyester, polyethylene, polyimide, polyethylenetelephthalate(PET), polyetheretherketone (PEEK). In addition, the walls of the catheter  1000  may be reinforced with a variety of structures, such as metal braids or coils. Such reinforcements may be along the length of the catheter  1000  or in various segments. 
         [0254]    For example, referring to  FIG. 53A , the catheter  1000  may have a proximal braided segment  1150 , a coiled segment  1152  and distal braided segment  1154 . The proximal braided segment  1150  provides increased column strength and torque transmission. The coiled segment  1152  provides increased steerability. The distal braided segment  1154  provides a blend of steerability and torque/column strength. In another example, referring to  FIG. 53B , the outer guiding catheter  1000  has a proximal double-layer braided segment  1151  and a distal braided segment  1154 . Thus, the proximal double-layer segment  1151  comprises a multi-lumen tube  1160  (having steering lumens  1162  for pullwires, distal ends of the steering lumens  1162  optionally embedded with stainless steel coils for reinforcement, and a central lumen  1163 ), an inner braided layer  1164 , and an outer braided layer  1166 , as illustrated in the cross-sectional view of  FIG. 53C . Similarly,  FIG. 53D  provides a cross-sectional view of the distal braided segment  1154  comprising the multi-lumen tube  1160  and a single braided layer  1168 . In a further example, referring to  FIG. 53E , the inner guiding catheter  1020  comprises a multi-lumen tube  1160  without reinforcement at its proximal end, a single braided layer middle segment  1170  and a single braided layer distal segment  1171 . Each of the single braided layer segments  1170 ,  1171  have a multi-lumen tube  1160  and a single layer of braiding  1168 , as illustrated in cross-sectional view  FIG. 53F . However, the segments  1170 ,  1171  are comprised of polymers of differing durometers, typically decreasing toward the distal end. 
         [0255]      FIG. 53G  illustrates an other example of a cross-section of a distal section of an outer guiding catheter  1000 . Here, layer  1130  comprises 55 D Pebax and has a thickness of approximately 0.0125 in. Layer  1131  comprises a 30 ppi braid and has a thickness of approximately 0.002 in. by 0.0065 in. Layer  1132  comprises 55 D Pebax and has a thickness of approximately 0.006 in. Layer  1133  comprises 30 ppi braid and has a thickness of approximately 0.002 in by 0.0065 in. And finally, layer  1134  comprises Nylon 11 and includes steering lumens for approximately 0.0105 in. diameter pullwires  1120 . Central lumen  1163  is of sufficient size for passage of devices. 
         [0256]      FIGS. 53H-53I  illustrate additional examples of cross-sections of an inner guiding catheter  1020 ,  FIG. 53I  illustrating a cross-section of a portion of the distal end and  FIG. 53I  illustrating a cross-section of a more distal portion of the distal end. Referring to  FIG. 53H , layer  1135  comprises 40 D polymer and has a thickness of approximately 0.0125 in. Layer  1136  comprises a 30 ppi braid and has a thickness of approximately 0.002 in. by 0.0065 in. Layer  1137  comprises 40 D polymer and has a thickness of approximately 0.006 in. Layer  1138  comprises a 40 D polymer layer and has a thickness of approximately 0.0035 in. And finally, layer  1139  comprises a 55 D liner. In addition, coiled steering lumens are included for approximately 0.0105 in. diameter pullwires  1120 . And, central lumen  1163  is of sufficient size for passage of devices. Referring to  FIG. 53I , layer  1140  comprises a 40 D polymer, layer  1141  comprises a 35 D polymer, layer  1142  comprises a braid and layer  1143  comprises a liner. In addition, coiled steering lumens  1144  are included for pullwires. And, central lumen  1163  is of sufficient size for passage of devices. 
         [0257]      FIGS. 54A-54C  illustrate an embodiment of a keying feature which may be incorporated into the catheter shafts. The keying feature is used to maintain relationship between the inner and outer guide catheters to assist in steering capabilities. As shown in  FIG. 54A , the inner guide catheter  1020  includes one or more protrusions  1400  which extend radially outwardly. In this example, four protrusions  1400  are present, equally spaced around the exterior of the catheter  1020 . Likewise, the outer guide catheter  1000  includes corresponding notches  1402  which align with the protrusions  1400 . Thus, in this example, the catheter  1000  includes four notches equally spaced around its central lumen  1018 . Thus, the inner guide catheter  1020  is able to be translated within the outer guide catheter  1000 , however rotation of the inner guide catheter  1020  within the outer guide catheter  1000  is prevented by the keying feature, i.e. the interlocking protrusions  1400  and notches  1402 . Such keying helps maintain a known correlation of position between the inner guide catheter  1020  and outer guide catheter  1000 . Since the inner and outer guide catheters  1020 ,  1000  form curvatures in different directions, such keying is beneficial to ensure that the compound curvature formed by the separate curvatures in the inner and outer guide catheters  1020 ,  1000  is the compound curvature that is anticipated. Keying may also increase stability wherein the curvatures remain in position reducing the possibility of compensating for each other. 
         [0258]      FIG. 54B  illustrates a cross-sectional view of the outer guiding catheter  1000  of  FIG. 54A . Here, the catheter  1000  includes a notched layer  1404  along the inner surface of central lumen  1018 . The notched layer  1404  includes notches  1402  in any size, shape, arrangement and number. Optionally, the notched layer  1404  may include lumens  1406 , typically for passage of pullwires  1120 . However, the lumens  1406  may alternatively or in addition be used for other uses. It may also be appreciated that the notched layer  1404  may be incorporated into the wall of the catheter  1000 , such as by extrusion, or may be a separate layer positioned within the catheter  1000 . Further, it may be appreciated that the notched layer  1404  may extend the entire length of the catheter  1000  or one or more portions of the length of the catheter  1000 , including simply a small strip at a designated location along the length of the catheter  1000 . 
         [0259]      FIG. 54C  illustrates a cross-sectional view of the inner guiding catheter  1020  of  FIG. 54A . Here, the catheter  1020  includes protrusions  1400  along the outer surface of the catheter  1020 . The protrusions  1400  may be of any size, shape, arrangement and number. It may be appreciated that the protrusions  1400  may be incorporated into the wall of the catheter  1020 , such as by extrusion, may be included in a separate cylindrical layer on the outer surface of the catheter  1020 , or the protrusions  1400  may be individually adhered to the outer surface of the catheter  1020 . Further, it may be appreciated that the protrusions  1400  may extend the entire length of the catheter  1000  or one or more portions of the length of the catheter  1020 , including simply a small strip at a designated location along the length of the catheter  1020 . 
         [0260]    Thus, the keying feature may be present along one or more specific portions of the catheters  1000 ,  1020  or may extend along the entire length of the catheters  1000 ,  1020 . Likewise, the notches  1402  may extend along the entire length of the outer guiding catheter  1020  while the protrusions  1400  extend along discrete portions of the inner guiding catheter  1000  and vice versa. It may further be appreciated that the protrusions  1400  may be present on the inner surface of the outer guiding catheter  1000  while the notches  1402  are present along the outer surface of the inner guiding catheter  1020 . 
         [0261]    Alternatively or in addition, one or more steerable portions of the catheter  1000  may comprise a series of articulating members  1180  as illustrated in  FIG. 55A . Exemplary embodiments of steerable portions of catheters comprising such articulating members  1180  are described in U.S. Pat. No. 7,682,319 (Attorney Docket No. 020489-001210US) incorporated herein by reference for all purposes.  FIG. 55B  illustrates the outer guide catheter  1000  having a steerable portion comprising articulating members  1180  at its distal end  1016 . 
         [0262]    Briefly, referring to  FIG. 55A , each articulating member  1180  may have any shape, particularly a shape which allows interfitting or nesting as shown. In addition, it is desired that each member  1180  have the capability of independently rotating against an adjacent articulating member  1180 . In this embodiment, the articulating members  1180  comprise interfitting domed rings  1184 . The domed rings  1184  each include a base  1188  and a dome  1186 . The base  1188  and dome  1186  have a hollow interior which, when the domed rings  1184  are interfit in a series, forms a central lumen  1190 . In addition, the dome  1186  allows each articulating member  1180  to mate against an inner surface of an adjacent domed ring  1184 . 
         [0263]    The interfitting domed rings  1184  are connected by at least one pullwire  1120 . Such pullwires typically extend through the length of the catheter  1000  and at least one of the interfitting domed rings  1184  to a fixation point where the pullwire  1120  is fixedly attached. By applying tension to the pullwire  1120 , the pullwire  1120  arcs the series of interfitting domed rings  1184  proximal to the attachment point to form a curve. Thus, pulling or applying tension on at least one pullwire, steers or deflects the catheter  1000  in the direction of that pullwire  1120 . By positioning various pullwires  1120  throughout the circumference of the domed rings  1184 , the catheter  1000  may be directed in any number of directions. 
         [0264]    Also shown in  FIG. 55A , each interfitting domed ring  1184  may comprise one or more pullwire lumens  1182  through which the pullwires  1120  are threaded. Alternatively, the pullwires  1120  may be threaded through the central lumen  1190 . In any case, the pullwires are attached to the catheter  1000  at a position where a desired curve is to be formed. The pullwires  1120  may be fixed in place by any suitable method, such as soldering, gluing, tying, welding or potting, to name a few. Such fixation method is typically dependent upon the materials used. The articulating members  1180  may be comprised of any suitable material including stainless steel, various metals, various polymers or co-polymers. Likewise the pullwires  1120  may be comprised of any suitable material such as fibers, sutures, metal wires, metal braids, or polymer braids. 
         [0265]    E. Handles 
         [0266]    As mentioned previously, manipulation of the guide catheters  1000 ,  1020  is achieved with the use of handles  1056 ,  1057  attached to the proximal ends of the catheters  1000 ,  1020 .  FIG. 56  illustrates a preferred embodiment of handles  1056 ,  1057 . As shown, handle  1056  is attached to the proximal end  1014  of outer guide catheter  1000  and handle  1057  is attached to the proximal end  1024  of inner guide catheter  1020 . Inner guide catheter  1020  is inserted through handle  1056  and is positioned coaxially within outer guide catheter  1000 . In this embodiment, the handles  1056 ,  1057  are not linked together as shown in the embodiment illustrated in  FIG. 48 . It may be appreciated that such handles  1056 ,  1057  may alternatively be connected by external connecting rods, bars or plates or by an additional external stabilizing base. An embodiment of a stabilizing base will be described in a later section. Referring back to  FIG. 56 , interventional catheter is inserted through handle  1057  and is positioned coaxially within inner guide catheter  1020  and outer guide catheter  1000 . 
         [0267]    Each handle  1056 ,  1057  includes two steering knobs  1300   a ,  1300   b  emerging from a handle housing  1302  for manipulation by a user. Steering knobs  1300   a  are disposed on a side of the housing  1302  and steering knobs  1300   b  are disposed on a face of the housing  1302 . However, it may be appreciated that such placement may vary based on a variety of factors including type of steering mechanism, size and shape of handle, type and arrangement of parts within handle, and ergonomics to name a few. 
         [0268]      FIG. 57  illustrates the handles  1056 ,  1057  of  FIG. 56  with a portion of the housing  1302  removed to reveal the assemblies of the handles. Each knob  1300   a ,  1300   b  controls a steering mechanism which is used to form a curvature in the attached catheter. Each steering mechanism includes a hard stop gear assembly  1304  and a friction assembly  1306 . Tension is applied to one or more pullwires by action of the hard stop gear assembly to form a curve in a catheter. Tension is maintained by the friction assembly. When tension is released from the one or more pullwires the catheter returns to a straightened position. 
         [0269]      FIG. 58  illustrates steering mechanisms within a handle wherein the housing  1302  is removed for clarity. Here, steering knob  1300   a  is attached to a hard stop gear assembly  1304  and a friction assembly (not in view) and steering knob  1300   b  is attached to a separate hard stop gear assembly  1304  and friction assembly  1306 . Steering knob  1300   a  is attached to a knob post  1318  which passes through a base  1308 , terminating in a knob gear wheel  1310 . The knob gear wheel  1310  actuates the hard stop gear assembly  1304 , thereby applying tension to one or more pullwires  1120 . 
         [0270]    The knob gear wheel  1310  is a toothed wheel that engages a disk gear wheel  1312 . Rotation of the steering knob  1300   a  rotates the knob post  1318  and knob gear wheel  1310  which in turn rotates the disk gear wheel  1312 . Rotation of the disk gear wheel  1312  applies tension to one or more pullwires extending through the attached catheter, in this example the outer guiding catheter  1000 . As shown, the outer guiding catheter  1000  passes through the base  1308 , wherein one or more pullwires  1120  extending through the catheter  1000  are attached to the disk  1314 . Such attachment is schematically illustrated in  FIG. 59 . Catheter  1000  is shown passing through base  1308 . A pullwire  1120  passing through a steering lumen  1162  in the catheter  1000  emerges from the wall of the catheter  1000 , passes through an aperture  1320  in the disk  1314  and is attached to an anchor peg  1316  on the disk  1314 . Rotation of the disk  1314  (indicated by arrow  1328 ) around disk post  1315  by action of the disk gear wheel  1312 , applies tension to the pullwire  1120  by drawing the pullwire  1120  through the aperture  1320  and wrapping the pullwire  1120  around the disk  1314  as it rotates. Additional rotation of the disk  1314  applies increasing tension to the pullwire  1120 . To limit the amount of tension applied to the pullwire  1120 , to limit curvature of the catheter and/or to avoid possible breakage of the pullwire  1120 , the rotation of the disk  1314  may be restricted by hard stop peg  1322  which is attached to the disk  1314  and extends into the base  1308 . 
         [0271]      FIGS. 60A-60B  illustrate how the hard stop peg  1322  is used to restrict rotation of disk  1314 .  FIGS. 60A-59B  provide a top view, wherein the disk  1314  is disposed on the base  1308 . The anchor peg  1316  is shown with the pullwire  1120  thereattached. A groove  1326  is formed in the base  1308  beneath the disk  1314  and forms an arc shape. The hard stop peg  1322  extends from the disk  1314  into the groove  1326  in the base  1308 . Referring now to  FIG. 60B , rotation of the disk  1314  around knob post  1318 , indicated by arrow  1330 , draws the pullwire  1120  through the aperture  1320  as previously described, wrapping the pullwire  1120  around the disk  1314 . As the disk  1314  rotates, the hard stop peg  1322  follows along the groove  1326 , as shown. The disk  1314  continues rotating until the hard stop peg  1322  reaches a hard stop  1324 . The hard stop  1324  is positioned in the groove  1326  and prevents further passage of the hard stop peg  1322 . Thus, disk  1314  rotation may be restricted to any degree of rotation less than or equal to 360 degrees by positioning of the hard stop  1324 . 
         [0272]    In some instances, it is desired to restrict rotation of the disk  1314  to a degree of rotation which is more than 360 degrees. This may be achieved with another embodiment of the hard stop gear assembly  1304 . Referring now to  FIGS. 61A-61B , a portion of such a hard stop gear assembly  1304  is shown.  FIG. 61A  illustrates the base  1308  and the disk post  1315  positioned therethrough. Also shown in the base  1308  is an aperture  1334  through which the knob post  1318 , knob gear wheel  1310  and friction assembly  1306  pass, and a passageway  1336  through which the catheter  1000  passes. In this embodiment of the hard stop gear assembly  1304 , a groove  1326  is also present in an arc shape around the disk post  1315 , however a ball  1332  is positioned in the groove  1326  rather than a hard stop peg  1322 . Disk  1314  is positioned over the groove  1326  and the ball  1332  as shown in  FIG. 61B . The disk  1314 , illustrated in  FIG. 61C , has a groove  1356  in its surface which is positioned adjacent to the base  1308 , the groove  1356  having an arc shape similar to the groove  1326  in the base  1308 . The ball  1332  is not fixedly attached to the base  1308  or the disk  1314  and is therefore free to move along the channel formed by the groove  1326  in the base  1308  and the groove in the disk  1314 . 
         [0273]      FIGS. 62A-62F  illustrate how rotation of the disk  1314  may be restricted by the ball  1332  to a degree of rotation which is more than 360 degrees.  FIGS. 62A-62F  illustrate the groove  1326  in the base  1308  wherein the groove  1326  has an arc shape around disk post  1315 . The groove  1326  does not form a complete circle; a first groove end  1350   a  and a second groove end  1350   b  form a wall which prevent passage of the ball  1332 . It may be appreciated that the groove ends  1350   a ,  1350   b  may be any distance apart, shortening the length of the groove  1326  by any amount, and allowing the ball  1332  movement, and hence catheter deflection, to be adjusted to any desired amount. To begin, referring to  FIG. 62A , the ball  1332  is positioned within the groove  1326  near the first groove end  1350   a . The disk  1314  has a matching groove  1352  (shape illustrated in dashed line) including a first groove end  1354   a  and a second groove end  1354   b . The disk  1314  is positioned over the ball  1332  so that the ball  1332  is near the second groove end  1354   b.    
         [0274]    Referring now to  FIG. 62B , the disk  1314  may be rotated while the ball  1332  remains in place. Here, the disk  1314  has rotated  90  degrees, as indicated by arrow  36000  and the position of the groove ends  1354   a ,  1354   b . Referring now to  FIG. 62C , the disk  1314  may be further rotated while the ball  1332  remains in place. Here, the disk  1314  has rotated  270  degrees, as indicated by arrow  36000  and the position of the groove ends  1354   a ,  1354   b . The disk  1314  may continue rotating to 360 degrees, as shown in  FIG. 62D , indicated by arrow  36000 . Here, the first groove end  1354   a  in the disk  1314  has contacted the ball  1332  and pushes the ball  1332  along groove  1326  in the base. Referring now to  FIG. 62E , the disk  1314  may be further rotated while the ball  1332  is pushed along the groove  1326  in the base  1308  by the first groove end  1354   a  in the disk  1314 . Here, the disk  1314  is shown to have rotated  540  degrees. Referring to  FIG. 62F , the disk  1314  rotates until the ball  1332  reaches the second groove end  1350   b  of the base  1308 , providing a hard stop. In this position, the ball  1332  is held between the first groove end  1354   a  of the disk  1314  and the second groove end  1350   b  of the base  1308  and further rotation of the disk  1314  is prevented. Thus, the disk  1314  was rotated approximately 660 degrees in this example. Any maximum degree of rotation may be set by positioning of groove ends  1350   a ,  1350   b  and/or groove ends  1354   a ,  1354   b . Additionally, in some embodiments, rotation can be limited by adding more than one ball  1332  to the groove  1326 , for example, two, three, four, five, six, seven, eight, nine, ten or more balls may be used to limit travel and hence curvature. 
         [0275]    It may be appreciated that one or more pullwires  1120  are attached to the disk  1314  in a manner similar to that illustrated in  FIG. 59 . Therefore, as the disk  1314  rotates, around disk post  1315  by action of the disk gear wheel  1312 , tension is applied to the pullwire  1120  by drawing the pullwire  1120  through the aperture  1320  and wrapping the pullwire  1120  around the disk  1314  as it rotates. Additional rotation of the disk  1314  applies increasing tension to the pullwire  1120 . Restriction of rotation as described above limits the amount of tension applied to the pullwire  1120 , to limit curvature of the catheter and/or to avoid possible breakage of the pullwire  1120 . 
         [0276]    As mentioned, each steering mechanism includes at least a hard stop gear assembly  1304  and a friction assembly  1306 . As described above, tension is applied to one or more pullwires by action of the hard stop gear assembly to form a curve in a catheter. Tension is maintained by the friction assembly.  FIG. 63  illustrates an embodiment of a friction assembly  1306 . The friction assembly  1306  essentially holds a steering knob, in this example steering knob  1300   b , and the associated knob post  1318  in a rotated position. Here, rotation of the knob  1300   b  and post  1318  rotates attached knob gear wheel  1310 . The knob gear wheel  1310  actuates the hard stop gear assembly  1304 , thereby applying tension to one or more pullwires  1120 . The knob gear wheel  1310  is a toothed wheel that engages a disk gear wheel  1312 . Rotation of the steering knob  1300   b  rotates the knob post  1318  and knob gear wheel  1310  which in turn rotates the disk gear wheel  1312 . Rotation of the disk gear wheel  1312  applies tension to one or more pullwires extending through the attached catheter, in this example the outer guiding catheter  1000 . 
         [0277]    The steering knob  1300   b  and knob post  1318  are held in a rotated position by friction provided by a frictional pad  1370 . The frictional pad  1370  is positioned between ring  1372  attached to the knob post  1318  and a plate  1374  attached to the base  1308 . The knob post  1318  extends from the knob  1300   b  through the ring  1372 , the frictional pad  1370  and then the plate  1374 . The plate  1374  has internal threads which mate with threads on the knob post  1318 . As the knob post  1318  rotates, the threads on the post  1318  advance through the threads on the plate  1374 . This draws the ring  1372  closer to the plate  1374 , compressing the frictional pad  1370  therebetween. Frictional pad  1370  may be comprised of any O-ring or sheet material with desirable frictional and compressibility characteristics, such as silicone rubber, natural rubber or synthetic rubbers, to name a few. In preferred embodiments, an EPDM rubber O-ring is used. Reverse rotation of the knob post  1318  is resisted by friction of the frictional pad  1370  against the ring  1372 . The higher the compression of the frictional pad  1370  the stronger the frictional hold. Therefore, as the steering knob  1300   b  is rotated and increasing amounts of tension are applied to the pullwires  1120 , increasing amounts of friction are applied to the ring  1372  to hold the knob  1300   b  in place. 
         [0278]    Manual reverse rotation of the steering knob  1300   b  releases tension on the pullwires  1120  and draws the ring  1372  away from the plate  1374  thereby reducing the frictional load. When tension is released from the pullwires  1120  the catheter  1000  returns toward a straightened position. 
         [0279]    It may be appreciated that each handle  1056 ,  1057  includes a steering mechanism for each curve to be formed in the attached catheter. Thus, as shown in  FIG. 57 , handle  1056  includes a steering mechanism to form the primary curve  1100  in outer guiding catheter  1000  and a steering mechanism to form the additional curve  1110 . Likewise, handle  1057  includes a steering mechanism to form the secondary curve  1104  in inner guiding catheter  1020  and a steering mechanism to form the angle theta  1070 . 
         [0280]    Some curves, such as the primary curve  1100 , secondary curve  1104  and additional curve  1110  each typically vary in curvature between a straight configuration and a curved configuration in a single direction. Such movement may be achieved with single set of a hard stop gear assembly  1304  and a friction assembly  1306 . However, other curves, such as the angle theta  1070 , may be formed in two directions as shown in  FIGS. 49C-49D . Such movement is achieved with two sets of the hard stop gear assembly  1304  and the friction assembly  1306 , each set controlling curvature in a single direction. 
         [0281]      FIG. 63  illustrates the presence of an additional set of the friction assembly  1306 ′. One or more pullwires  1120 ′, such as an opposing set as illustrated in  FIG. 52D , extending within the wall of the catheter  1000  are attached to the disk  1314 ′ in the same manner as pullwires  1120  are attached to disk  1314 . The disks  1314 ,  1314 ′ are arranged so that rotation of steering knob  1300   b  in one direction applies tension to the pullwires  1120  via disk  1314  and rotation of steering knob  1300   b  in the opposite direction applies tension to the pullwires  1120 ′ via disk  1314 ′. Likewise, the additional friction assembly  1306 ′ is shown having a ring  1372 ′ attached to the knob post  1318  and a frictional pad  1370 ′ disposed between the ring  1372 ′ and the opposite side of the plate  1374 . Therefore, as rotation of the steering knob  1300   b  in the opposite direction applies tension to the pullwires  1120 ′ via disk  1314 ′, the frictional pad  1370 ′ applies tension to the ring  1372 ′ holding the knob post  1318 ′ in place. 
         [0282]    It may be appreciated that various other mechanisms may be used for tensioning and holding pullwires  1120  in place. Example mechanisms that may alternatively be used include clutches, ratchets, levers, knobs, rack and pinions, and deformable handles, to name a few. 
         [0283]    F. Interventional System 
         [0284]      FIG. 64  illustrates an embodiment of an interventional system 3 of the present invention. An embodiment of the multi-catheter guiding system 1 of the present invention is shown comprising an outer guide catheter  1000 , having a proximal end  1014  and a distal end  1016 , and an inner guide catheter  1020 , having a proximal end  1024  and a distal end  1026 , wherein the inner guide catheter  1020  is positioned coaxially within the outer guide catheter  1000 , as shown. In addition, a hemostatic valve  1090  is disposed within handle  1056  or external to handle  1056  as shown to provide leak-free sealing with or without the inner guide catheter  1020  in place. The valve  1090  also prevents back bleeding and reduces the possibility of air introduction when inserting the inner guide catheter  1020  through the outer guide catheter  1000 . An example of a hemostatic valve  1090  is illustrated in  FIG. 64A , however any suitable valve or hemostatic valve may be used to provide similar functions. In  FIG. 64A , the valve  1090  has a first end  1091 , a second end  1092  and a lumen  1093  therethrough. The inner wall of lumen  1093  is preferably tapered toward end  1091  and may further include a plurality of tapered axial channels configured to receive the protrusions  1400  on the inner guide catheter  1020 . The first end  1091  is attached to the outer guide catheter  1000  and the second end  1092  is free. Referring now back to  FIG. 64 , the distal ends  1016 ,  1026  of catheters  1000 ,  1020 , respectively, are sized to be passable to a body cavity, typically through a body lumen such as a vascular lumen. 
         [0285]    To assist in inserting the fixation device  14  through a hemostatic valve  1090 , a fixation device introducer may be used. For example, when the fixation device  14  is loaded on a delivery catheter  300  and an inner guide catheter  1020 , insertion of the fixation device  14 , delivery catheter  300  and inner guide catheter  1020  through an outer guide catheter  1000  involves passing the fixation device  14  through a hemostatic valve  1090  on the outer guide catheter  1000 . To reduce any trauma to the fixation device  14  by the hemostatic valve  1090 , a fixation device introducer may be used. An embodiment of a fixation device introducer  1420  is illustrated in  FIG. 64B . The introducer  1420  includes a loading body  1422  and an insertion endpiece  1424 . The fixation device  14  is loaded into the loading body  1422  and into the insertion endpiece  1424  to approximately the dashed line  1428 . The insertion endpiece  1424  has a split end creating individual split sections  1430 , in this embodiment, four split sections  1430 . By compressing the split sections  1430 , the endpiece  1424  forms a taper. Such a taper is then inserted through a hemostatic valve  1090 , so that the insertion endpiece  1424  creates a smooth passageway through the valve for the fixation device  14 . Once the insertion endpiece  1424  is inserted through the valve  1090 , the fixation device  14 , and attached delivery catheter  300  and inner guide catheter  1020 , may then be advanced through the fixation device introducer  1420 . The fixation device introducer  1420  also includes a hemostatic valve within the loading body  1422  to prevent any backbleeding or leakage through the introducer  1420 . 
         [0286]    Manipulation of the guide catheters  1000 ,  1020  is achieved with the use of handles  1056 ,  1057  attached to the proximal ends of the catheters  1000 ,  1020 . As shown, handle  1056  is attached to the proximal end  1014  of outer guide catheter  1000  and handle  1057  is attached to the proximal end  1024  of inner guide catheter  1020 . Inner guide catheter  1020  is inserted through handle  1056  and is positioned coaxially within outer guide catheter  1000 . 
         [0287]    An embodiment of the delivery catheter  300  of the present invention is inserted through handle  1057  and is positioned coaxially within inner guide catheter  1020  and outer guide catheter  1000 . Therefore, a hemostatic valve  1090  is disposed within handle  1057  or external to handle  1057  as shown to provide leak-free sealing with or without the delivery catheter  300  in place. The valve  1090  functions as described above. The delivery catheter  300  includes a shaft  302 , having a proximal end  322  and a distal end  324 , and a handle  304  attached to the proximal end  322 . A fixation device  14  is removably coupled to the distal end  324  for delivery to a site within the body. 
         [0288]    The outer guide catheter  1000  and/or the inner guide catheter  1020  are precurved and/or have steering mechanisms to position the distal ends  1016 ,  1026  in desired directions. Precurvature or steering of the outer guide catheter  1000  directs the distal end  1016  in a first direction to create a primary curve while precurvature and/or steering of the inner guide catheter  1020  directs distal end  1026  in a second direction, differing from the first, to create a secondary curve. Together, the primary and secondary curves form a compound curve. Advancement of the delivery catheter  300  through the coaxial guide catheters  1000 ,  1020  guides the delivery catheter  300  through the compound curve toward a desired direction, usually in a direction which will position the fixation device  14  in a desired location within the body. 
         [0289]      FIG. 65  illustrates portions of another embodiment of an interventional system 3 of the present invention. Handles  1056 ,  1057  of the multi-catheter guiding system 1 of the present invention are shown. Each handle  1056 ,  1057  includes a set of steering knobs  1300   a ,  1300   b , as shown. Manipulation of the guide catheters  1000 ,  1020  is achieved with the use of the steering knobs  1300   a ,  1300   b  attached to the proximal ends of the catheters  1000 ,  1020 . Handle  304  of the delivery catheter  300  is also shown, including the proximal element line handle  312 , the lock line handle  310 , the actuator rod control  314  and the actuator rod handle  316 , among other features. The handle  304  is supported by the support base  306  which is connected to the handle  1057 . 
         [0290]    It may be appreciated the above described systems 3 are not intended to limit the scope of the present invention. The systems 3 may include any or all of the components of the described invention. In addition, the multi-catheter guiding system 1 of the present invention may be used to introduce other delivery catheters, interventional catheters or other devices. Likewise, the delivery catheter  300  may be introduced through other introducers or guiding systems. Also, the delivery catheter  300  may be used to deliver other types of devices to a target location within the body, including endoscopic staplers, devices for electrophysiology mapping or ablation, septal defect repair devices, heart valves, annuloplasty rings and others. 
         [0291]    In addition, many of the components of the system 3 may include one or more hydrophilic coatings. Hydrophilic coatings become slippery when wet, eliminate the need for separate lubricants. Thus, such coatings may be present on the multi-catheter guiding system, delivery catheter, and fixation device, including the proximal elements and distal elements, to name a few. 
         [0292]    Further, the system 3 may be supported by an external stabilizer base  1440 , an embodiment of which is illustrated in  FIG. 66 . Stabilizer base  1440  maintains the relative positions of the outer guide, inner guide and delivery catheter during a procedure. In this embodiment, the base  1440  comprises a platform  1442  having a planar shape for positioning on or against a flat surface, such as a table or benchtop. The base  1440  further includes a pair of handle holders  1444 ,  1448 , each attached to the platform  1442  and extending upwardly from the platform  1442 , either angularly or perpendicularly. Handle holder  1444  includes a notch  1446  for holding the outer guiding catheter  1000 , as illustrated in  FIG. 67 , thereby supporting the handle  1056 .  FIG. 67  shows the handle  1056  attached to the outer guiding catheter  1000  positioned so that the proximal end  1014  of the outer guiding catheter  1000  rests in the notch  1446 . Referring back to  FIG. 66 , handle holder  1448  includes an elongate portion  1452  having a trough  1450  and a hooked end  1454 . As shown in  FIG. 68 , handle  1057  rests on the elongate portion  1452  and the handle  304  rests on hooked end  1454  so that the inner guiding catheter  1020  extends from the handle  1057  to the handle  1056  and continues on within outer guiding catheter  1000 . The handle  304  is additionally supported by support base  306 , as shown. 
         [0293]    It may be appreciated that the stabilizer base  1440  may take a variety of forms and may include differences in structural design to accommodate various types, shapes, arrangements and numbers of handles. 
         [0294]    G. Kits 
         [0295]    Referring now to  FIG. 69 , kits  1500  according to the present invention comprise any of the components described in relation to the present invention. The kits  1500  may include any of the components described above, such as the outer guide catheter  1000  including handle  1056 , the inner guide catheter  1020  including handle  1057 , the delivery catheter  300  and the fixation device  14  and instructions for use IFU. Optionally, any of the kits may further include any other system components described above, such as various interventional tools  1040 , or components associated with positioning a device in a body lumen, such as a guidewire  1202 , dilator  1206  or needle  1204 . The instructions for use IFU will set forth any of the methods as described above, and all kit components will usually be packaged together in a pouch  1505  or other conventional medical device packaging. Usually, those kit components which will be used in performing the procedure on the patient will be sterilized and maintained within the kit. Optionally, separate pouches, bags, trays or other packaging may be provided within a larger package, where the smaller packs may be opened separately to separately maintain the components in a sterile fashion. 
         [0296]    While the foregoing is a complete description of the preferred embodiments of the invention, various alternatives, substitutions, additions, modifications, and equivalents are possible without departing from the scope of the invention. For example, in many of the above-described embodiments, the invention is described in the context of approaching a valve structure from the upstream side—that is, the atrial side in the case of a mitral valve. It should be understood that any of the foregoing embodiments may be utilized in other approaches as well, including from the ventricular or downstream side of the valve, as well as using surgical approaches through a wall of the heart. Moreover, the invention may be used in the treatment of a variety of other tissue structures besides heart valves, and will find usefulness in a variety of tissue approximation, attachment, closure, clamping and ligation applications, some endovascular, some endoscopic, and some open surgical. 
         [0297]    Again, although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that various alternatives, modifications and equivalents may be used and the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.