Patent Publication Number: US-2012041548-A1

Title: Apparatus for atrioventricular valve repair

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/287,011, filed Nov. 23, 2005. The parent patent application is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to medical methods and apparatus, and more particularly, to methods and apparatus for the endovascular or minimally invasive surgical repair of atrioventricular valves of the heart, including the mitral valve and the tricuspid valve. 
     The heart includes four valves that direct blood through the two sides of the heart. The mitral valve lies between the left atrium and the left ventricle and controls the flow of blood into the left side of the heart. The valve includes two leaflets, an anterior leaflet and a posterior leaflet, that close during systole. The leaflets are passive in that they open and close in response to pressure induced to the leaflets by the pumping of the heart. More specifically, during a normal cycle of heart contraction (systole), the mitral valve functions as a check valve to prevent the flow of oxygenated blood back into the left atrium. In this manner, oxygenated blood is pumped into the aorta through the aortic valve. 
     Occasionally, the mitral valve is formed abnormally through a congenital condition. More often, however, the mitral valve degenerates with age. Among the problems that can develop is mitral valve regurgitation in which the mitral valve leaflets become unable to close properly during systole, thus enabling leakage to flow through the mitral valve during systole. Over time, regurgitation of the mitral valve can adversely affect cardiac function and may compromise a patient&#39;s quality of life and/or life-span. 
     Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve. For example, the valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, or the papillary muscles themselves may become damaged or otherwise dysfunctional. Moreover, the valve annulus may become damaged or weakened and may limit the ability of the mitral valve to close adequately during systole. 
     Known treatments for mitral valve regurgitation commonly rely on valve replacement or annuloplasty, or strengthening of the mitral valve through surgical repairs and/or implanting a mechanical structure within the mitral valve. For example, the most prevalent and widely accepted known techniques to correct mitral valve regurgitation, repair the mitral valve via open heart surgery. During such an invasive surgical procedure, it is known to suture adjacent segments of the opposed valve leaflets together in a procedure known as a “bow-tie” or “edge-to-edge” surgical technique. Although each of the afore-mentioned treatments can be effective, generally known treatments rely on open heart surgery wherein the patient&#39;s chest is opened and the patient&#39;s heart is stopped while the patient is place on a cardiopulmonary bypass. The need to open the patient&#39;s chest and to place the patient on a cardiopulmonary bypass creates inherent risks that may be traumatic to the patient. 
     Percutaneously treatments are less invasive than the treatments mentioned above, but such treatments may be less effective and more difficult to effect repair because of the limited amount of space in and around the mitral valve in which to maneuver a repair device or devices. For example, U.S. Pat. No. 6,875,224 to Grimes describes a percutaneous mitral valve repair method in which the opposed leaflets are each immobilized to enable the two leaflets to be fastened together. Furthermore, U.S. Pat. No. 6,6290,534 to St. Goar et al. describes a plurality of embodiments for use in endovascular repair of cardiac valves in which, in each embodiment, both leaflets are grasped and held firmly in position prior to permanent treatment. However, grasping both leaflets while the patient&#39;s heart is beating may be a time-consuming and laborious task that demands a coordinated effort on the part of the surgical team. Moreover, to facilitate grasping both leaflets percutaneously may require that the patient&#39;s heart be temporarily stopped or slowed by drugs or other techniques. Slowing and/or stopping the patient&#39;s heart during surgery may increase the risks to the patient. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a method of repairing an atrioventricular valve in a patient is provided. The method comprises accessing the patient&#39;s atrioventricular valve percutaneously, securing a fastening mechanism to a valve leaflet, and coupling the valve leaflet, while the patient&#39;s heart remains beating, to at least one of a ventricular wall adjacent the atrioventricular valve, a papillary muscle, at least one valve chordae, and a valve annulus to facilitate reducing leakage through the valve. 
     In another aspect, a method of repairing a mitral valve in the heart of a patient is provided. The method comprises accessing the patient&#39;s mitral valve percutaneously, securing a first end of a fastening mechanism to a valve leaflet of the mitral valve, and coupling a second end of the fastening mechanism to a cardiac structure other than a mitral valve leaflet to facilitate reducing leakage through the patient&#39;s mitral valve during ventricular systole. 
     In a further aspect, a method of enhancing operation of a patient&#39;s heart valve is provided. The method comprises inserting a guide catheter along the venous system of the patient to approach the mitral valve, guiding a fastening mechanism towards one of a mitral valve and a tricuspid valve within the patient&#39;s heart, and securing a first end of the fastening mechanism to one of the mitral valve and the tricuspid valve using one of fusing, gluing, stapling, clipping, riveting, anchoring, and suturing. The method also comprises securing a second end of the fastening mechanism to a cardiac structure other than a valve leaflet to facilitate enhancing operation of the valve during ventricular systole. 
     In an additional aspect, a medical kit for use in repairing a mitral valve is provided. The kit includes a guide catheter and a fastening mechanism. The guide catheter is configured for insertion along the venous system of the patient to approach the mitral valve. The fastening mechanism is positionable percutaneously within the patient using the guide catheter. The fastening mechanism includes a first end and an opposite second end. The first end is configured to couple to the mitral valve using one of fusing, gluing, stapling, clipping, riveting, anchoring, and suturing. The second end is configured to only couple to a cardiac structure other than a valve leaflet to facilitate enhancing operation of the valve during ventricular systole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of the left and right ventricles of a human heart in diastole; 
         FIG. 2  is an another cross-sectional view of the heart shown in  FIG. 1  during systole; 
         FIG. 3  is an exemplary schematic illustration of a fastening mechanism that may be used to facilitate repair of a cardiac valve within the heart shown in  FIGS. 1 and 2 ; 
         FIG. 4  is an enlarged view of a portion of the fastening mechanism shown in  FIG. 1  and coupled to a papillary muscle in the heart shown in  FIGS. 1 and 2 ; 
         FIG. 5  is a schematic view of an alternative embodiment of a portion of a fastening mechanism that may be used to facilitate repair of a cardiac valve within the heart shown in  FIGS. 1 and 2 ; 
         FIG. 6  is a schematic view of an another alternative embodiment of a portion of a fastening mechanism that may be used to facilitate repair of a cardiac valve within the heart shown in  FIGS. 1 and 2 ; 
         FIG. 7  is a schematic view of a further alternative embodiment of a portion of a fastening mechanism that may be used to facilitate repair of a cardiac valve within the heart shown in  FIGS. 1 and 2 ; and 
         FIG. 8  is a flowchart illustrating an exemplary method for the endovascular repair of a cardiac valve. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a cross-sectional view of the left and right ventricles  10  and  12 , respectively, of a human heart  14  during diastole. Ventricles  10  and  12  are separated by an interatrial septum  15 .  FIG. 2  is a cross-sectional view of heart  14  during systole. The present invention provides methods and apparatus for the endovascular repair of cardiac valves, particularly atrioventricular valves  16 , which inhibit back-flow of blood from a heart ventricle during contraction (systole). In particular, the present invention may be used in repairing, but is not limited to repairing, mitral valves  20 . 
     As used herein, the term “endovascular,” refers to procedure(s) of the present invention that are performed with interventional tools and supporting catheters and other equipment introduced to the heart chambers from the patient&#39;s arterial or venous vasculature remote from the heart. The interventional tools and other equipment may be introduced percutaneously, i.e., through an access sheath, or may be introduced via a surgical cut down, and then advanced from the remote access site through the vasculature until they reach heart  14 . As such, the methods and apparatus described herein generally do not require penetrations made directly through an exterior heart muscle, i.e., myocardium, although there may be some instances where penetrations will be made interior to the heart, e.g., through the interatrial septum to provide for a desired access route. Moreover, as will be appreciated by one of ordinary skill in the art, the methods and apparatus described herein are not limited to use with percutaneous and intravascular techniques, but rather the present invention may be used with open surgical procedures as well. 
     The atrioventricular valves  16  are each located at a junction of the atria and their respective ventricles. The atrioventricular valve  16  extending between the right atrium  30  and the right ventricle  12  has three valve leaflets (cusps) and is referred to as the tricuspid or right atrioventricular valve  31 . The atrioventricular valve  16  between the left atrium  32  and the left ventricle  10  is a bicuspid valve having only two leaflets or cusps  34  and is generally referred to as the mitral valve  20 . 
     During operation of the heart  14 , the valve leaflets  34  open during diastole when the heart atria fill with blood, allowing the blood to pass into the ventricle. During systole, however, the valve leaflets  34  are pushed together such that the free edges  36  of the leaflets  34  are closed against each other along a line of coaptation to prevent the back-flow of blood into the atria. Back flow of blood or “regurgitation” through the mitral valve  20  is facilitated to be prevented when the leaflets  34  are closed, such that the mitral valve  20  functions as a “check valve” which prevents back-flow when pressure in the left ventricle  10  is higher than that in the left atrium  32 . 
     The mitral valve leaflets  34  are attached to the surrounding heart structure along an annular region referred to as the valve annulus  40 . The free edges  36  of the leaflets  34  are secured to the lower portions of the left ventricle  10  through tendon-like tissue structures, known as chordae tendineae or chordae  42 . The chordae  42  are attached to the papillary muscles  44  which extend upwardly from the lower portions of the left ventricle and interventricular septum  46 . 
     A number of structural defects in the heart can cause mitral valve regurgitation. For example, ruptured chordae  42  may cause a valve leaflet  34  to prolapse if inadequate tension is induced to the leaflet  34  through the remaining unruptured chordae  42 . Moreover, and for example, regurgitation may also occur in patients suffering from cardiomyopathy, wherein the heart  14  is dilated and the increased size prevents the valve leaflet edges  36  from contacting each other properly, or in patients who have suffered ischemic heart disease wherein the functioning of the papillary muscles  44  may be impaired. Generally during regurgitation the free edges  36  of the anterior and posterior leaflets  34  do not contact sufficiently along the line of coaptation, but rather leakage may occur through a gap defined between the leaflets  34 . 
       FIG. 3  is an exemplary schematic illustration of a fastening mechanism  50  that may be used to facilitate repair of an atrioventricular valve  16  within heart  14  (shown in  FIGS. 1 and 2 ).  FIG. 4  is an enlarged view of a portion of the fastening mechanism shown in  FIG. 3  and coupled to a papillary muscle  44 . Fastening mechanism  50  includes a first attachment end  60  and a second attachment end  62 . In the exemplary embodiment, first attachment end  60  includes a generally deformable clip portion  64  that is sized and shaped to couple to a free edge  36  (shown in  FIGS. 1 and 2 ) of a leaflet  34  (shown in  FIGS. 1 and 2 ). In alternative embodiments, first attachment end  60  is coupled to leaflet  34  without using clip portion  64 . 
     Overall dimensions of, and material properties used in fabricating, clip portion  64  are variably selected based on the leaflet  34  being repaired. In the exemplary embodiment, portion  64  is pinched or crimped against a leaflet free edge  36  to facilitate repair of the valve as described in more detail below. More specifically, in this embodiment, fastening mechanism  50  is coupled to valve  16  such that an outer surface of leaflet free edge  36  is grasped without mechanism  50  penetrating the leaflet tissue. Specifically, in the exemplary embodiment, the leaflet free edge  36  is crimped between opposing sides  66  and  68  of portion  64 . In another embodiment, portion  64  is coupled to a free edge  36  using any suitable means that enables portion  64  to remain coupled to leaflet free edge  36 , such as, but not limited to, with gluing, stapling, suturing, fusing, riveting, external clips, or any combination thereof 
     Alternatively, first attachment end  60  may be secured to leaflet  34  through atraumatic partial, or full penetration, or piercing of leaflet  34 . For example, first attachment end  60  and/or portion  64  may include attachment prongs that extend from clip portion  64  and that are configured to pinch, partially penetrate, or pierce the leaflet  34 . In one alternative embodiment, first attachment end  60  may be inserted from a first side of the leaflet  34 , through leaflet  34 , and outward from an opposite second side of the leaflet  34 . In such an embodiment, in use first attachment end  60  is coupled to, and secured against the second side of the leaflet. In another alternative embodiment, first attachment end is inserted only partially through the leaflet  34 , and thus is secured to leaflet tissue intermediate the first and second sides of the leaflet. 
     In another alternative embodiment, first attachment end  60  is attached to leaflet  34  using any suitable means that will enable fastening mechanism  50  to function as described herein, such as, but not limited to, an adhesive process, a riveting process, a suturing process, a stapling process, or any combination thereof. In a further alternative embodiment, a threaded locking member or any other suitable mechanical coupling, may be used to secure first attachment end  60  to the leaflet. In another alternative embodiment, attachment end  60  may be fused directly to the leaflet  34  using a known fusion process in which laser, RF, microwave or ultrasonic energy, for example, is applied at specified coaptation points. 
     In the exemplary embodiment, clip portion  64  is fabricated from a formable material that is coated in a protective cloth-like material. Clip portion  64  may be fabricated from any suitable biocompatible material that enables fastening mechanism  50  to function as described herein, such as, but not limited to, titanium alloys, platinum alloys, stainless steel, or any combination thereof. In the exemplary embodiment, clip portion  64  is coated with a fabric material such as, but not limited to, a DACRON® material, a TEFLON® material, a GORE-TEX®, or any material or combination thereof that enables clip portion  64  to function as described herein. In one embodiment, clip portion  64  is covered by a material that encourages tissue in-growth. 
     In the exemplary embodiment, a tensioning member  70  extends from clip portion  64  to second attachment end  62 . The overall size, shape, and material used in member  70  is variably selected depending on the application. For example, in one embodiment, member  70  is fabricated from a mesh material. The relative location of member  70  with respect to clip portion  64  is variably selected based on the amount of tension to be induced, the desired locations for the tension to be induced, and based on the leaflet  34  being repaired. 
     In the exemplary embodiment, tensioning member  70  includes an attachment pad  74 . The overall size, shape, thickness, and material used in fabricating pad  74 , as well as the number and location of pad  74 , are variably selected based on the intended use of fastening mechanism  50 . Alternatively, fastening mechanism  50  includes more than one tensioning member  70 . In another alternative embodiment, fastening mechanism  50  may include a single tensioning member  70  that includes a forked or bifurcated end that includes two pads  74 . In yet another alternative embodiment, fastening tensioning member  70  does not include pad  74 . In a further alternative embodiment, fastening mechanism  50  includes at least one tensioning member that is formed with a looped end that is sized to circumscribe the cardiac structure to which it is attached, and is cinchable to facilitate securing fastening mechanism  50  to the papillary muscle  44 . Tensioning member  70  facilitates inducing tension to the leaflet  34  being repaired, and pad  74  facilitates distributing loading across the papillary muscle  44 . Moreover, pad  74  is sized for placement along an external surface of papillary muscle  44  when fastening mechanism  50  is coupled to the papillary muscle  44 . 
     In the exemplary embodiment, tensioning member  70  and pad  74  are formed integrally together. Alternatively, pad  74  may be securely coupled to member  70  using any of a plurality of known coupling means. In the exemplary embodiment, member  70  is coupled to papillary muscle  44  using a fastener (not shown) that is inserted at least partially through papillary muscle  44 . In one embodiment, the fastener has a tack-like configuration. In another embodiment, the fastener is mechanically coupled to the papillary muscle  44  using, for example, a suitable threaded coupling. In a further embodiment, at least one of a pair of interlocking fasteners is inserted through a pad  74  prior to insertion through the papillary muscle  44  and prior to the two fasteners being interlocked. In another embodiment, pad  74  is coupled in position against the papillary muscle  44  by a cinch-type fastener that circumscribes the papillary muscle  44  when securely cinched. In another alternative embodiment, pad  74  is coupled directly to the papillary muscle  44  using any suitable means that will enable fastening mechanism  50  to function as described herein, such as, but not limited to, an adhesive process, a riveting process, a suturing process, a coil or corkscrew device, a stapling process, external clips, or any combination thereof. In a further alternative embodiment, a threaded locking member and a self-locking or spin-lock ratcheting fastener may be used to secure member  70  to the papillary muscle  44 . In yet a further alternative embodiment, pad  74 , and/or tensioning member  70  is coupled to the papillary muscle  44  using a flat ribbon that has been heat-set in the shape of double loops. 
     Pad  74  and member  70  may be fabricated from any material that enables pad  74  and member  70  to function as described herein. For example, pad  74  and member  70  may be fabricated from, but are not limited to being fabricated from, a DACRON® material, a TEFLON® material, a GORE-TEX®, or any material or combination. In addition, depending on the application, pad  74  and member  70  may be fabricated from, but are not limited to being fabricated from a superelastic material or a shaped memory alloy (SMA) material, such as, but not limited, to Nitinol®, stainless steel, plastic, or any of several known shaped memory alloys (SMA) that have properties that develop a shaped memory effect (SME). In one embodiment, pad  74  is fabricated from a material that encourages tissue in-growth. 
     During use, to repair a mitral valve  20  using fastening mechanism  50 , first attachment end  60  is coupled securely to mitral valve  20  and second attachment end  62  is coupled to a cardiac structure, such as the papillary muscle  44 . Alternatively, second attachment end  62  may be coupled to any cardiac structure other than a mitral valve leaflet  34  such as, but not limited to, a ventricular wall  46  adjacent the atrioventricular valve  30 , a valve chordae  42 , either intact or ruptured, a valve annulus  36 , an interatrial septum  15  or any combination thereof. In the exemplary embodiment, second attachment end  62  is coupled to the papillary muscle  44 . More specifically, when end  62  is firmly secured to the papillary muscle  44 , pad  74  is retained tightly against the exterior surface of the papillary muscle  44 . As such, loading induced to the papillary muscle from fastening mechanism  50  is distributed across pad  74 . 
     In the exemplary embodiment, overall dimensions and material properties of member  70  are variably selected to facilitate inducing a desired tension to leaflet  34  and to facilitate improving the ability of the atrioventricular valve  16  to close against the elevated pressures within the ventricle during systole. More specifically, member  70  is variably selected to facilitate modifying operation of the leaflet  34  such that the free ends  36  of the opposed leaflets  34  again contact each other during systole along the line of coaptation to prevent the back-flow or regurgitation of blood through the mitral valve  20  into the atria. 
       FIG. 5  is a schematic view of an alternative embodiment of a portion of a fastening mechanism  100  that may be used to facilitate repair of a cardiac valve  16  (shown in  FIGS. 1 and 2 ). Fastening mechanism  100  is substantially similar to fastening mechanism  50  (shown in  FIGS. 3 and 4 ) and, components of fastening mechanism  100  that are identical to components of fastening mechanism  50  are identified in  FIG. 5  using the same reference numerals used in  FIGS. 3 and 4 . Accordingly, fastening mechanism  100  includes first attachment end  60 , second attachment end  62  (shown in  FIGS. 3 and 4 ), and at least one tensioning member  110  extending therebetween. In the exemplary embodiment, tensioning member  110  includes an anchor member  112 . It should be noted that although attachment end  60  is illustrated, the anchor member  112  may also be included at attachment end  62  and/or end  60 , or at any suitable location between ends  60  and  62  depending on the application. 
     Tensioning member  110  is substantially similar to tensioning member  70  and as such, facilitates inducing tension to the leaflet  34  (shown in  FIGS. 1 and 2 ) being repaired. In the exemplary embodiment, tensioning member  110  and anchor member  112  are formed integrally together. Alternatively, anchor member  112  may be securely coupled to tensioning member  110  using any of a plurality of known coupling means. In the exemplary embodiment, member  110  is coupled to leaflet  34  using anchor member  112 , or any other cardiac structure other than a mitral valve leaflet  34 , such as, but not limited to, a ventricular wall  46  (shown in  FIGS. 1 and 2 ) adjacent the atrioventricular valve  30  (shown in  FIGS. 1 and 2 ), a valve chordae  42  (shown in  FIGS. 1 and 2 ), either intact or ruptured, a valve annulus  36  (shown in  FIGS. 1 and 2 ), an interatrial septum  15  (shown in  FIGS. 1  and  2 ), a papillary muscle  44  (shown in  FIGS. 1 ,  2 , and  4 ), or any combination thereof 
     In the exemplary embodiment, anchor member  112  has a distal end  114  that is pointed and is self-piercing that facilitates transmural attachment to a ventricular wall. Accordingly, the anchor member distal end  114  may be fabricated of any material having sufficient rigidity to pierce, and/or at least partially penetrate, through a portion of the cardiac component to which it is intended to be attached. For example, the distal end  114  may be fabricated from, but is not limited to being fabricated from, stainless steel, titanium, various shaped memory or superelastic materials, metal alloys, various polymers, and combinations thereof. Moreover, the geometries, tip sharpness, and dimensions of anchor member  112  are variably selected to ensure a desired amount of piercing, if any, occurs. In an alternative embodiment, the anchor member distal end  114  does not actually pierce the cardiac structure, but rather is positioned in a desired position by a surgical instrument, such as, but not limited to a piercing catheter or a needle. 
     In the exemplary embodiment, anchor member  112  includes a plurality of anchoring arms  120  that are biased outwardly from tensioning member  110 . Alternatively, anchor member  112  may include, but is not limited to including, a plurality of penetrating and/or non-penetrating petals, wings, propellers, coils, arms, ribbons, tubes, loops, grappling hooks, barbs, or clips, that are extend outwardly from tensioning member  110  to enable fastening mechanism  100  to function as described herein. Moreover, in other embodiments, anchor member  112  may include expandable arms that expand outwardly from a compressed state. For example, in one embodiment, the arms  120  function similarly to an umbrella and include a pleated, supported material member that is biased outwardly, as described herein. Furthermore, the cross-sectional shape of arms  120  is illustrated as exemplary only. Rather, anchor member  112 , arms  120 , and tensioning member  110  may be fabricated with any cross-sectional shape that enables fastening mechanism  100  to function as described herein. 
     In the exemplary embodiment, arms  120  are biased outwardly such as is possible using pre-shaped, resilient metallic rods, for example. Alternatively, the arms  120  may be fabricated from any suitable material and in any suitable manner that enables arms  120  to function as described herein. For example, arms  120  may be fabricated from, but are not limited to being fabricated from Nitinol®, stainless steel, plastic, superelastic alloys, polymers, or any of several known shaped memory alloys (SMA) that have properties that develop a shaped memory effect (SME). Moreover, arms  120  may be fabricated from, but are not limited to being fabricated from, a DACRON® material, a TEFLON® material, a GORE-TEX®, or any material or combination. In one embodiment, arms  120  are fabricated from a material that encourages tissue in-growth. 
     During installation, after distal end  114  has penetrated at least partially through the cardiac component to which it is being attached, arms  120  are advanced through the penetration or opening and are displaced outwardly. More specifically, as tensioning member  100  is withdrawn or retracted from the opening in an opposite direction to that of insertion within the opening, because arms  120  are biased outwardly from tensioning member  100 . More specifically, the biasing of the arms  120  causes the arms  120  to contact the surface of the cardiac component radially outward from the opening, such that the arms  120  are not retractable through the opening as tensioning member  100  is withdrawn from the opening. Rather, as tensioning member  100  is withdrawn from the opening, anchor member  112  is secured against a tissue surface of the cardiac component. 
       FIG. 6  is a schematic view of an alternative embodiment of a portion of a fastening mechanism  150  that may be used to facilitate repair of a cardiac valve  16  (shown in  FIGS. 1 and 2 ). Fastening mechanism  150  is substantially similar to fastening mechanisms  50  and  100  (shown in  FIGS. 3 and 4 , and  5 , respectively) and, components of fastening mechanism  150  that are identical to components of fastening mechanism  50  and  100  are identified in  FIG. 6  using the same reference numerals used in  FIGS. 3-5 . Accordingly, fastening mechanism  150  includes first attachment end  60  (shown in  FIGS. 3-5 ), second attachment end  62  (shown in  FIGS. 3 and 4 ), and at least one tensioning member  152  extending therebetween. In the exemplary embodiment, tensioning member  152  includes an anchor member  156 . It should be noted that although attachment end  62  is illustrated, the anchor member  156  may also be included at attachment end  60  and/or end  62 , or at any suitable location between ends  60  and  62  depending on the application. 
     Tensioning member  152  is substantially similar to tensioning member  70 , and/or tensioning member  110 , and as such, facilitates inducing tension to the leaflet  34  (shown in  FIGS. 1 and 2 ) being repaired. In the exemplary embodiment, tensioning member  152  and anchor member  156  are formed integrally together. Alternatively, anchor member  156  may be securely coupled to tensioning member  152  using any of a plurality of known coupling means. In the exemplary embodiment, member  152  is coupled to leaflet  34  using anchor member  156 , or any other cardiac structure other than a mitral valve leaflet  34 , such as, but not limited to, a ventricular wall  46  (shown in  FIGS. 1 and 2 ) adjacent the atrioventricular valve  30  (shown in  FIGS. 1 and 2 ), a valve chordae  42  (shown in  FIGS. 1 and 2 ), either intact or ruptured, a valve annulus  36  (shown in  FIGS. 1 and 2 ), an interatrial septum  15  (shown in  FIGS. 1 and 2 ), a papillary muscle  44  (shown in  FIGS. 1 ,  2 , and  4 ), or any combination thereof. 
     In the exemplary embodiment, anchor member  156  is formed with a cork-screw or coil configuration and has a distal end  160  that is pointed and is self-piercing. Accordingly, the anchor member  156  may be fabricated of any material having sufficient rigidity to pierce, and/or at least partially penetrate, through a portion of the cardiac component to which it is intended to be attached. For example, the distal end  156  may be fabricated from, but is not limited to being fabricated from, stainless steel, titanium, various shape memory or superelastic materials, metal alloys, various polymers, and combinations thereof. In an alternative embodiment, the anchor member  156  is not self-tapping, but rather is threadably coupled within a starter hole formed a surgical instrument, such as, but not limited to a piercing catheter or a needle. 
     In one embodiment, anchor member  156  may be formed from a shape memory wire that is annealed or heat-set in a straight configuration and then coiled. In such an embodiment, anchor member  156  may be processed to have different properties by varying the diameter and tension therein along its length. For example, when anchor member  156  is heated to a pre-determined temperature, such as with RF energy, a designated portion of anchor member  156  will become a randomly oriented mass of material having self-locking struts to prevent disentanglement. When the anchor member  156  is heated to a different pre-determined temperature, a full entanglement of occurs such that anchor member  156  is compressed together. 
     In an alternative embodiment, anchor member  156  includes a plurality of tines or arms that are biased outwardly from member  156 , and more particularly from tip  160 . In such an embodiment, the arms facilitate securing the anchor member  156  in position within the cardiac structure to which it is embedded. Moreover, in other embodiments, anchor member  156  may include expandable arms that expand outwardly from a compressed state. Alternatively, anchor member  156  may include other self-locking struts that facilitate preventing member  156  from backing out of the cardiac structure to which it is threadalby coupled. Furthermore, the cross-sectional shape of anchor member  156  is illustrated as exemplary only. Rather, anchor member  156  and tensioning member  152  may be fabricated with any cross-sectional shape, dimensions, or material that enables fastening mechanism  150  to function as described herein. For example, anchor member  156  may be formed with, but is not limited to being formed with, a self-tapping screw configuration, a mesh configuration, or with a helical configuration. 
     Moreover, in another embodiment, anchor member  156  is formed with a coiled configuration having a helical filament that includes a secondary helical structure that includes, for example, a plurality of loops. In such an embodiment, anchor member  156  may include an inner element fabricated from a shaped memory material and an outer element that is substantially concentrically aligned with respect to the inner element, and is fabricated from a second material, such as a radiopaque material or a heat-activated material. Furthermore, in other embodiments, to facilitate endovascular orientation, the coil may be fabricated with a stacked coil configuration in which no space is defined between adjacent windings of the coil, but rather, the coil assumes a coil configuration when heated to a pre-determined temperature as it is deployed. 
       FIG. 7  is a schematic view of an alternative embodiment of a portion of a tensioning member  200  that may be used to facilitate repair of a cardiac valve  16  (shown in  FIGS. 1 and 2 ). Tensioning member  200  extends between first and second attachment ends  60  and  62  (shown in  FIGS. 3 and 4 ) and in the exemplary embodiment, includes at least two anchoring loops  202  and  204 , and an adjustment mechanism  206  extending between loops  202  and  204 . In the exemplary embodiment, loops  202  and  204  are each formed integrally with respective attachment ends  60  and  62 . In another embodiment, loops  202  and  204  are coupled to ends  60  and  62  using any suitable coupling means. 
     In the exemplary embodiment, adjustment mechanism  206  enables each attachment end  60  and  62  to be coupled to a leaflet  34  (shown in  FIGS. 1 and 2 ) and to any other cardiac structure other than a mitral valve leaflet  34 , without tension being induced to either end  60  or  62 . Moreover, once ends  60  and  62  are coupled to the leaflet  34  and the cardiac structure, adjustment mechanism  206  enables a pre-determined tension to be induced between the leaflet  34  and the cardiac structure. 
     In the exemplary embodiment, adjustment mechanism  206  functions similarly to a drawstring and includes a locking mechanism  220  that facilitates maintaining a desired tension between the leaflet  34  and the cardiac structure. More specifically, after ends  60  and  62  have each been securely coupled to the leaflet and the cardiac structure, as adjustment loop  222  is pulled away from ends  60  and  62 , adjustment mechanism  206  is drawn radially inward between ends  60  and  62 , inducing tension between the leaflet  34  and the cardiac structure, and locking mechanism  220  is coupled to adjustment loop  222  to facilitate ensuring that ends  60  and  62  are maintained in their relative position such that the tension induced between ends  60  and  62  is maintained. In an alternative embodiment, adjustment mechanism  206  does not include locking mechanism  222 , but rather any suitable method of maintaining the tension between ends  60  and  62  may be utilized, such as, but not limited to, self-locking twist fastener devices or swivel fasteners. Moreover, in a further embodiment, adjustment mechanism  206  does not include locking mechanism  220 , but rather the tension induced by the placement of loop  222  is maintained by a knot tied in position adjacent loop  222 . 
     In alternative embodiments, other adjustment mechanisms other than mechanism  206  may be used, such as, but not limited to, the installation of a spreader bar mechanism within at least one loop of a daisy chained tension member, the use of a turnbuckle-type mechanism, and/or the use of tensioning member that is shortened as it is twisted, such as would be possible with a tourniquet-type attachment. Moreover, in further alternative embodiments, at least a portion of adjustment mechanism  206  is fabricated from a shaped metal alloy that is formed into a component that when coupled within a fastener assembly either constricts or bows outwardly to induce tension between the ends  60  and  62 . 
       FIG. 8  is a flowchart illustrating an exemplary method for the endovascular repair of a cardiac valve. Initially, the mitral valve, or other atrioventricular valve being repaired is accessed percutaneously  300 . Depending on the point of vascular access, the approach to the mitral valve may be “antegrade” and require entry into the left atrium by crossing the interatrial septum. Alternatively, approach to the mitral valve can be “retrograde” wherein the left ventricle is entered through the aortic valve. Once access  300  is achieved, the interventional tools and supporting catheter(s) will be positioned  302  endovascularly adjacent the valve being repaired. As will be appreciated by one of ordinary skill in the art, the present invention may be used with open surgical techniques wherein the heart is stopped and the heart valve accessed through the myocardial tissue. 
     The interventional tools used for performing the valve repairs may be specifically designed for use with the present invention, or existing tools may be modified to accommodate the present invention. For example, in one embodiment, a 1° catheter is used to position or guide a plurality of smaller catheters in which the 1° catheter is used to accomplish general positioning of the device relative to the valve being repaired, and the smaller catheters facilitate the more precise positioning necessary to repair the valve in accordance with the present invention. In other embodiments, a guide catheter, a needle bearing catheter, an introducer, or a similar device may be used. 
     Once positioned  302 , the leaflet to be repaired is captured  310  and the first attachment end of the fastening mechanism is securely coupled to the leaflet  312 . Specifically, as described above, the fastening mechanism may be coupled to the leaflet in a plurality of manners, but in each case, the first attachment end of the mechanism is securely coupled to the valve leaflet in need of repair. The leaflet may be captured  310  using any of a plurality of known methods, including, but not limited to using grasping pins, articulated graspers, vacuum-assisted graspers, or any other suitable method. 
     The second attachment end of the fastening mechanism is then securely coupled  330  to a cardiac structure other than a mitral valve leaflet. The tension induced  332  to the mitral valve leaflet is selected to substantially simulate the same tension, operation, and functionality of a natural chordae member coupled to the leaflet. In at least some embodiments, tension induced to the mitral valve leaflet is adjustable via adjustments of the tensioning member. 
     After repairing the valve leaflet, flow through the valve can be observed by conventional cardiac imaging techniques, such as trans-esophegeal echocardiography (TEE), intracardiac echocardiography (ICE) or other ultrasonic imaging technique, fluoroscopy, angioscopy, catheter based magnetic resonance imaging (MRI), computed tomography (CT) and the like. By observing the flow through the repaired valves, it can be determined whether or not back flow or regurgitation has ceased, or whether the tension induced to the leaflet requires adjustment. 
     Exemplary embodiments of methods and fastener mechanisms for use in repairing atrioventricular valves are described above in detail. Although the methods are herein described and illustrated in association with the above-described atrioventricular valve, it should be understood that the present invention may be used with any atrioventricular valve. More specifically, the fastener mechanisms and methods of repair are not limited to the specific embodiments described herein, but rather, aspects of each fastener mechanism and/or method of repair may be utilized independently and separately from other fastener mechanisms and/or repair methods. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.