Patent Publication Number: US-2021169651-A1

Title: Edge to edge repair device for valves

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/945,453, filed Dec. 9, 2019, which application is incorporated herein by reference in its entirety for all purposes. 
    
    
     FIELD 
     The present disclosure relates generally to the field of implantable medical devices. In particular, the present disclosure relates to medical devices, systems, and methods for cardiac treatment. 
     BACKGROUND 
     Mitral regurgitation occurs when the native mitral valve fails to close properly, causing blood to flow back into the left atrium from the left ventricle during the systolic phase of heart contraction. Mitral regurgitation may have many causes, including but not limited to leaflet prolapse, dysfunctional or damaged papillary muscles, congenital defects, rheumatic fever, and/or stretching of a valve annulus. Mitral regurgitation can interrupt the body&#39;s ability to effectively process oxygen, causing fatigue and lightheadedness. Over time, regurgitation may lead to enlargement of the left atrium and compromised heart function. 
     SUMMARY 
     According to one aspect, a leaflet fixation device includes a unitary elongate body including a proximal neck portion including a first tissue engaging surface and a distal portion including an arm having a second tissue engaging surface. The arm may include an open configuration where the first tissue engaging surface may be spaced away from the second tissue engaging surface, the arm being biased towards a closed configuration where the second tissue engaging surface may be retained adjacent to the first tissue engaging surface by a bias force, and where the bias force may be at least equal to a leaflet grasping force. 
     In various embodiments, the arm may be one of a plurality of arms biased towards the closed configuration and in the closed configuration and each arm of the unitary elongate body may be adjacent to a different part of the proximal neck portion of the unitary elongate body. In one embodiment, in the closed configuration, a first arm may be adjacent to a first surface of the proximal neck portion of the unitary elongate body and a second arm may be adjacent to a second, opposing surface of the proximal neck portion of the unitary elongate body. In various embodiments, the proximal neck portion, the distal portion, or both may include a tissue retention feature. The tissue retention feature may be one of a plurality of tissue retention features disposed on the proximal neck portion, the distal portion or a combination of the proximal neck portion and the distal portion and configured to penetrate but not puncture tissue, puncture tissue or both. 
     The tissue retention feature may include a barb, a hook, a tooth, a tine or a combination thereof. The tissue retention feature may include a feature that promotes tissue ingrowth into the unitary elongate body. Each arm of the plurality of arms may be configured to move independently from other arms of the plurality of arms. In one embodiment, the unitary elongate body includes a length and a width, and the distal portion of the unitary elongate body may be apportioned along its width to define the plurality of arms, each of the plurality of arms having a common thickness. In one embodiment, the unitary elongate body includes a length, a width and a thickness, and the distal portion of the unitary elongate body may be apportioned along its thickness to define the plurality of arms, each of the plurality of arms having a common width. In one embodiment, the proximal neck portion may be apportioned into a plurality of necks, and where the unitary elongate body may include a biased configuration where at least one arm may be adjacent to at least one neck. In various embodiments, a weight of the leaflet fixation device may be between 50-150 milligrams. 
     According to another aspect, a system includes a leaflet fixation device including a unitary elongate body including a proximal neck portion including a first tissue engaging surface and a distal portion including an arm having a second tissue engaging surface. The arm includes an open configuration where the first tissue engaging surface may be spaced away from the second tissue engaging surface, the arm being biased towards a closed configuration where the second tissue engaging surface may be retained adjacent to the first tissue engaging surface by a bias force. The system also includes a delivery tool including, for each arm, a spreader mechanism configured to independently translate the arm between the closed configuration and the open configuration. 
     In one embodiment the arm may be one of a plurality of arms biased towards the closed configuration, and in the closed configuration each arm of the unitary elongate body may be adjacent to a different part of the proximal neck portion of the unitary elongate body. In some embodiments, the proximal neck portion of the unitary elongate body, the distal portion of the unitary elongate body, or both may include a tissue retention feature including a barb, a hook, a tooth, a tine, a pore, a texture or a combination thereof. In one embodiment, the spreader mechanism may include a jaw, pivotably coupled to a distal end of the delivery tool, the jaw including a coupler configured to releasably couple the arm to the jaw, where rotation of the jaw in a first direction pulls the arm of the leaflet fixation device away from the proximal neck portion of the leaflet fixation device to the open configuration to provide a space therebetween configured for valvular tissue and where rotation of the jaw in a second direction returns the arm to the closed configuration. In one embodiment, each spreader mechanism includes a spreader arm, rotatably coupled to a distal end of the delivery tool, the spreader arm disposed to push the arm of the leaflet fixation device away from the proximal neck portion of the leaflet fixation device to the open configuration when rotated in a first direction to provide a space therebetween configured for valvular tissue, where rotation of the spreader arm in a second direction returns the arm to the closed configuration. In one embodiment, the proximal neck portion, the arm of the distal portion, or both of the leaflet fixation device include a tissue retention feature and the spreader mechanism may be configured to independently translate the arm between the closed configuration and the open configuration and to inhibit engagement between a tissue engagement feature and tissue during placement of the leaflet fixation device. 
     According to a further aspect, a method of joining leaflets of a cardiac valve includes the steps of advancing a delivery tool carrying a fixation device at its distal end towards a valve treatments site, the fixation device including a unitary elongate body including a proximal neck portion and a distal portion including an arm, where the arm includes an open configuration where the proximal neck portion of the unitary elongate body may be spaced away from the arm and a closed configuration where the arm may be retained adjacent to the proximal neck portion of the unitary elongate body by a bias force, and where the arm may be biased in the closed configuration at rest. The method includes positioning the delivery tool proximate to a first valve leaflet, actuating a spreader mechanism of the delivery tool to angularly displace the arm away from the proximal neck portion of the unitary elongate body into the open configuration, positioning the proximal neck portion of the unitary elongate body and the arm on opposing sides of the first valve leaflet and actuating the spreader mechanism to restore the arm to the closed configuration. 
     In some embodiments, the arm may be a first arm of a pair of arms biased towards the closed configuration, and the method may include the steps of positioning the delivery tool proximate to a second valve leaflet, actuating the spreader mechanism of the delivery tool to angularly displace a second arm away from the proximal neck portion of the unitary elongate body into the open configuration, positioning the proximal neck portion of the unitary elongate body and the second arm on opposing sides of the second valve leaflet and actuating the spreader mechanism to restore the second arm to the closed configuration. 
     With such an arrangement, a unitary, lightweight leaflet clip is provided for use in securing valve leaflets for cardia repair procedures. Using a unitary body to form the leaflet clip reduces the number and type of components involved in the leaflet clipping solution, thereby reducing the overall weight of the fixation device and failure risks associated with chronic interaction between components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting embodiments of the present disclosure are described by way of example with reference to the accompanying figures, which are schematic and not intended to be drawn to scale. In the figures, each identical or nearly identical illustrated component is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure. In the figures: 
         FIGS. 1A-1D  are perspective views of one embodiment of a valve fixation device disclosed herein; 
         FIGS. 2A-2D  are perspective views of one embodiment of a valve fixation device disclosed herein; 
         FIGS. 3A-3C  are perspective views of one embodiment of a valve fixation device disclosed herein; 
         FIG. 4  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 5  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 6  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 7  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 8  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 9  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIG. 10  illustrates one embodiment of a valve fixation device disclosed herein. 
         FIGS. 11A-11F  illustrate various configurations and features of embodiments of a delivery mechanism for use in delivering the valve fixation devices disclosed in various embodiments herein, to a valve treatment site. 
         FIGS. 12A-12C  illustrate various configurations of one embodiment of a delivery mechanism for use in delivering the valve fixation devices disclosed in various embodiments herein, to a valve treatment site. 
         FIGS. 13A-13D  illustrate examples of steps that may be performed for treatment of a heart valve using the valve fixation devices disclosed in various embodiments herein. 
         FIG. 14  is a top down view of a mitral valve following delivery of a leaflet fixation device as disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides methods and devices for grasping and securing tissues such as valve leaflets to treat cardiac valve regurgitation. In one embodiment, a valve fixation device may comprise a unitary elongate member comprising at least one neck portion and at least one arm portion, the elongate member being biased towards a closed configuration wherein at least a pair of tissue engaging surfaces of the elongate member (for example, a tissue engaging surface on the neck portion and a tissue engaging surface of the arm portion) are held adjacent to each other by a bias force. The bias force is at least equal to a valve leaflet grasping force, enabling the fixation device to grasp and retain leaflets as part of cardiac treatment. A delivery tool including a spreader may independently translate the tissue engaging surfaces to enable cardiac leaflets to be captured and retained by and/or between the tissue engaging surfaces. The valve fixation device may include at least two arms, each of which may be independently controlled to grasp and capture opposing leaflets of a valve, such as the anterior and posterior leaflets of a mitral valve, to reduce the size of the valve opening and improve cardiac performance. In some embodiments, at least a portion of the fixation device includes one or more tissue retention mechanisms, including but not limited to teeth, barbs, hooks, tines, pores, or surface texture, etc., that improves fixation device retention. In some embodiments, the delivery tool may include one or more features, such as a shield or a standoff, configured to reduce interaction between tissue retention mechanisms and tissue during positioning of the fixation device. 
     These and other beneficial aspects of an implant and method of deployment are described in more detail below. Although embodiments of the present disclosure may be described with specific reference to mitral valves, the principles disclosed herein may be readily adapted to facilitate reconstruction of any valve annulus, for example including a tricuspid valve annulus and/or may similarly benefit any other dilatation, valve incompetency, valve leakage and other similar heart failure conditions. 
     As used herein, the term “distal” refers to the end farthest away from the medical professional when introducing a medical device into a patient, while the term “proximal” refers to the end closest to the medical professional when introducing a medical device into a patient. 
       FIGS. 1A-1D  illustrate perspective views of one embodiment of a fixation device  100  that may be used as disclosed herein to reduce the size of a valve, for example by joining together valve leaflets. The fixation device  100  is shown formed of a unitary, elongate body  105  having a proximal neck portion  110  and a distal portion  130  comprising one or more arms of the elongate body. In various embodiments, the body  105  may be manufactured from a shape memory alloy (SMA) or similar materials with the ability to recover a pre-defined configuration. Such materials include, but are not limited to, Nickel Titanium, Graphene, Nitinol, copper-aluminum-nickel and the like. 
     Such materials are referred to herein as biased towards the pre-defined configuration. A bias force is the recovery force of the shaped memory alloy, e.g., the force exhibited by the body to recover (e.g. return to its pre-defined configuration) under the strain of deformation from the pre-defined configuration. The bias force is a function of the size, shape, and composition of shaped material. In one example embodiment, the overall elongate body may have a length of 14 mm-24 mm, to provide a “folded” length between 7 mm and 12 mm, a width of 2 mm-6 mm and a thickness of 0.25-0.75 mm, providing a device having a grasping force of between 0.1 and 0.5 lbs. Although a fixation device having ranges of length, width, and/or thickness is disclosed, it is appreciated that one of skill in the art may develop similar fixation devices capable of providing similar bias or grasping forces that urge the fixation device towards a closed, tissue retaining configuration, and such similar devices are considered to be within the scope of this disclosure. 
     According to one aspect, the fixation device may be manufactured to provide sufficient grasping force to enable it to fixedly attach to leaflet tissue without imparting undue gravitational forces that may disrupt remaining valve function. In this way, the fixation device has a mass that is not significantly larger than necessary such that the weight of the fixation device does not negatively impact the leaflet or nearby tissue. For example, a device  100  may weigh between 50-150 mg, for example 65 mg, or the like, e.g., such that a weight of a clamp may not undesirably interfere with leaflet operation. 
       FIG. 1A  illustrates the unitary elongate body  105  in an unbiased state. In one embodiment, the unitary elongate body  105  has a length L that extends longitudinally along an axis A, a width W, perpendicular to the Axis A, and a thickness T. In some embodiments, such as that shown in  FIG. 1A , the width is fixed along the length L. In other embodiments, the width may vary (increase, decrease) along the length L. Similarly, although the thickness T is shown to be relatively uniform along the length and width, it is appreciated that in various embodiments the thickness may vary (increase, decrease) along the length L or across the width W. In the embodiment of  FIG. 1A , as will be described in more detail below, the distal portion  130  of the unitary elongate body  105  is shown apportioned across its width into a plurality of arms, such as arm  120  and arm  122 . 
     The unitary elongate body has several surfaces, including a forward surface  112 , shown in  FIG. 1A , and a rear surface  111  (shown in  FIG. 1C ). At least a portion of the proximal neck portion  110  of the unitary elongate body  105  includes a tissue engaging portion  115 , and at least a portion of a distal end of an arm, such as arm  120 , also includes a tissue engaging surface portion  125 . Although certain portions of the body  105  are designated as tissue engaging surfaces, it is appreciated that the tissue engaging surface portion may include a larger or smaller area than that designated, and that the tissue engaging portion may be any surface of the body  105  that contacts leaflet tissue during use. 
     According to one embodiment, the pre-defined configuration of the unitary elongate body comprises a closed configuration wherein common surfaces of proximal and distal portions of the unitary elongate body are positioned close to and opposing each other to form a leaflet fixation device. 
     For example,  FIG. 1B  illustrates the unitary elongate body  100  in its biased, closed, configuration. Each arm,  120 ,  122  is differently biased, formed such that distal ends  121 ,  123  of the respective arms  120 ,  122  contact different surfaces (e.g.,  111 ,  112 ) of the proximal neck portion  110  of the leaflet fixation device  100 . For example, distal end  121  of arm  120  contacts the proximal neck portion  110  of the device  100  at a tissue engagement surface  115 , while the distal end  123  of arm  122  contacts the proximal neck portion  110  of the device  100  on the opposing surface. As a result, the fixation device  100  leverages the resistive forces of shape memory materials to provide a unitary, low profile, light weight retention mechanism for valve leaflet treatment. 
       FIG. 1C  illustrates the rearward facing surface  111  of the fixation device  100  comprising biased arms  120 ,  122  and shown including tissue engaging surface  117  on its proximal end  110 . The embodiment of the fixation device  100  of  FIGS. 1A-1D  comprises a two-armed retention device, wherein each of the arms are biased towards an opposing surface of the proximal neck portion of the body  105 . Thus, a distal tissue engaging surface  127  of arm  122 , in a biased configuration, contacts or is otherwise close to and facing a tissue engaging surface  117 . In  FIG. 1C , the arm  122  is shown pulled away from the proximal neck portion  110  of body  105  by an angular extent  133 . The angular extent  133  corresponds to an open configuration of the arm  122 , that leaving a gap between the body  105  and the arm  122  that is sufficiently wide to enable leaflet tissue to be disposed therebetween. In some embodiments, the angular extent  133  may range between 75 and 120 degrees or more, for example, to leave a gap in the range of 90 degrees. 
       FIG. 1D  is a diagram illustrating the fixation device  100  in a fully open configuration, with both arms  120 ,  122  spaced apart from the proximal neck portion  110  such that the distal tissue engaging surfaces  125 ,  127  are spaced apart from the proximal tissue engaging surfaces  117 . As described in more detail below, according to one aspect, each of the arms  120 ,  122  of the fixation device  100  may be independently opened and closed, enabling greater precision and accuracy when grabbing tissue by enabling grasping of individual leaflets during the procedure. 
     In the embodiment of  FIGS. 1A-1D , where the arms of the distal portion of the unitary elongate body are formed by apportioning the width of the distal portion into segments, the distal tissue engaging surface ( 125 ,  127 ) comprises only approximately half (or other portion, when arms have different widths) of the width W of the unitary body  105 . In such a configuration, the grasping force of each arm should be selected to compensate for the reduced size of the tissue engaging surface. 
       FIGS. 2A-2D  illustrate various views of a second embodiment of a fixation device  200  comprising a unitary elongate body  205  having a length L, a width W, and a thickness T which may correspond generally in L and W dimension to the device  100  of  FIGS. 1A-1D , and may range in thickness T from the same dimension to double the thickness or more at least partially along its length, as will be described. In  FIG. 2A , the unitary elongate body  205  is shown in an unbiased configuration. The body  205  includes a proximal neck portion  210  and a distal portion  230 , the proximal neck portion  210  comprising a tissue engaging surface  215  and the distal portion  230  comprising a tissue engaging surface  225 . In some embodiments, the thickness of the distal portion  230  may be greater than the thickness of the proximal neck portion  210 , although the disclosure is not so limited. Arms  220 ,  222  of the fixation device  200  may be formed by apportioning the thickness T of the distal portion into segments. With such an arrangement, the tissue engaging surface area  225  of the distal end  230  of the fixation device  200  utilizes the entire width W of the body  205 , enabling a more comprehensive use of the proximal tissue engaging portion  215  for securing tissue. In some embodiments, increasing the tissue engaging surface area in this manner may enable lighter weight materials to be used for a fixation device capable of achieving the desired bias force for leaflet grasping. 
       FIG. 2B  is a side view of the fixation device  200 . The distal portion  230  of the device  200  is shown bisected along its thickness T, forming two arms  220 ,  222  which are biased towards a closed configuration wherein the distal ends of arms  220 ,  222  contact, or are otherwise close to and facing opposing surfaces of the proximal neck portion  210  of the device  200 . 
       FIG. 2C  illustrates the device  200  in a partially open configuration, wherein the arm  220  has been pulled or pushed back from the biased, closed configuration to expose distal tissue engaging surface  227  and proximal tissue engaging surface  217  (not visible) to leaflet tissue. 
       FIG. 2D  illustrates the device  200  in a fully open configuration, wherein both arms  220 ,  222  have been pushed or pulled away from their biased, closed configuration to an open configuration wherein gaps G 1 , G 2  enable leaflet tissue to be disposed between tissue engaging surfaces of the device  200  for capture. 
       FIGS. 3A-3C  illustrate an alternate embodiment of a fixation device  300 . Like the device  200  of  FIGS. 2A-2C , the device of  FIGS. 3A-3C  includes arms  320 ,  322  formed by bisecting the distal portion of the elongate body  305  along its thickness. The arms  320 ,  322  are biased towards a closed configuration, wherein distal portions of the arms  320 ,  322  contact, or are close to and facing the proximal neck portion  310  of the body  305 . In the embodiment of  FIGS. 3A, 3C , the proximal neck portion  310  of the body  305  includes one or more tissue retention features, such as tissue retention feature  323 . In  FIGS. 3A-3C , the tissue retention features  323  are shown disposed upon opposing surfaces  311 ,  312  the proximal neck portion  310  of the elongate body  305 . The illustrated tissue retention features  323  comprise a tooth that extends at an angle from a longitudinal axis A of the elongate body. In one embodiment, the tooth is distally angled, to secure leaflet tissue, when disposed between the arms  320 ,  322  and the proximal tissue engaging surfaces, against pullout due to chronic palpatory forces. 
     In some embodiments, the one or more tissue retention mechanisms may be arranged in columns extending along at least one of the plurality of arms such that the plurality of retention mechanisms are in different planes. The protrusions may extend not more than 50% through a thickness of a wall of the leaflet, e.g., the protrusions may not extend into the wall of a leaflet and may instead distort the tissue. The protrusions may extend a distance from an arm that may be about 0.5 millimeters to about 1.5 millimeters. 
       FIG. 3B  is a cross-sectional view of device  300 , illustrating tissue retention mechanisms  323  deployed on opposing surfaces  311 ,  312  of the proximal end  310  of the device  300 . As shown in  FIG. 3B , as the arms  320 ,  322  are urged towards their biased configuration, the arms will push any captured tissue towards the tissue retention mechanisms  323 , improving the affixation of the device  300  to leaflet tissue.  FIG. 3C  illustrates the device  300  in a fully open configuration, providing gaps G 1 , G 2  between the proximal end  310  of the device  300  and respective arms  320 ,  322 . It is appreciated that, when employing tissue retention mechanisms such as teeth  323 , the resiliency of the unitary elongate body may be selected to ensure that the gaps G 1 , G 2  are wide enough to accommodate leaflet tissue without interference from the retention mechanisms  323 . In other words, the open configuration should provide a gap at least equal to expected leaflet tissue thickness plus the protrusion extent of any tissue retention mechanism used to retain the leaflet. 
     Although  FIGS. 3A-3C  illustrate tissue retention mechanisms relatively equally disposed on opposing surfaces of the proximal neck portion  310  of the body  305 , it is appreciated that tissue retention mechanisms may take many forms and may be deployed in various patterns which are optimized to the particular tissue to be captured by the fixation device, as well as to secure the device against chronic palpatory forces that act upon it. Thus, although a particularly shaped tooth is shown in  FIGS. 3A-3C , the present disclosure is not limited to the use of teeth, but additionally encompasses barbs, hooks, tines, or another feature that may be used to engage or interact with leaflet tissue. 
       FIGS. 4-7  illustrate various embodiments of tissue retention devices that employ different tissue retention mechanisms.  FIG. 4  is a cross section view of one embodiment of a device  400  that includes a plurality of tissue retention mechanisms disposed on the proximal neck portion  401  of the device  400 , including distally facing teeth  402  and proximally facing teeth  404 . Such embodiments may improve the ability of tissue to be grasped between the proximally and distally facing teeth, to assist in retaining leaflet tissue by the device  400 . 
       FIG. 5  is a cross section view of an embodiment of a device  500  that includes a plurality of tissue retention mechanisms, wherein some tissue retention mechanisms, such as neck teeth  512 , are disposed on the proximal neck portion  501  of the device  500 , and other tissue retention mechanisms, such as tissue engaging teeth  515 , are disposed on the arms  514 ,  516 . With such an arrangement, tissue retention is applied to both sides of a captured leaflet, further increasing the strength of affixation of the device  500  to the leaflet. 
       FIG. 6  is a cross section view of an embodiment of a device  600  that includes a plurality of tissue retention mechanisms, wherein some tissue retention mechanisms, such as neck teeth  622 ,  624 , are disposed on the proximal neck portion  601  of the device  600 , and other tissue retention mechanisms, such as tissue engaging teeth  625 , are disposed on the arms  626 ,  628 . The embodiment of  FIG. 6  illustrates how the pattern of tissue retention mechanisms may vary in accordance with the particular tissue or chronic use conditions of the clip. 
       FIG. 7  is a side view perspective of an embodiment of a device  700  that includes a plurality of tissue retention mechanisms, including both tissue retention mechanisms that are configured to pierce tissue, such as neck teeth  702 ,  703  on proximal neck portion  701 , and tissue engaging teeth  705  on arms  704 ,  706 , as well as tissue retention mechanisms such as pores  707  which are configured to encourage endothelialization (e.g., tissue ingrowth) into the device  700 . For example, the pore size may range from between 5 and 30 μm. The pores may be distributed over portion or all of the elongate body. Other methods of promoting tissue ingrowth along a portion of or the entire elongate body, for example by modifying the surface texture of the elongate body, coating the body with pro-angiogenic drugs, etc., are also within the scope of this disclosure. 
       FIGS. 8-10  illustrate alternate embodiments of tissue fixation devices which may be formed from a resilient material that leverages the bias forces of a closed configuration to provide leaflet grasping forces for retaining the leaflet within the device. 
       FIG. 8  illustrates a fixation device  800  comprising an elongate body  805  formed into two opposing arms  820 ,  822 , and bent so that the proximal end  810  of the elongate body faces the distal end  830  of the elongate body, and portions  821 ,  823  of the arms are biased to a closed configuration such that tissue engaging surfaces  811 ,  813  of the arms are adjacent to and face each other to enable tissue to be grasped between the arms  820 ,  822 . Each arm  820 ,  822  is shown to include tissue retention mechanisms such as teeth  802  disposed in parallel columns along surfaces  811 ,  813  of the device  800 . In the embodiment of  FIG. 8 , the proximal end  810  and distal end  830  of the elongate body  805  may each include a coupler  832 ,  833 , that may be used, for example, to couple the device  800  to a delivery tool to manage delivery of the device  800  to the valve leaflet. As described in more detail below, in one embodiment, the coupler  832  may include a bore (not shown), having a central lumen  835  extending therethrough configured to accept a pin or other mechanism to releasably secure the arm to a delivery tool which is configured to move each arm  820 ,  822  independently from other arms of the body  805 . 
       FIG. 9  is a side view of an embodiment of a fixation device  900  formed from a unitary elongate body  905  which has been apportioned along its thickness to form both proximal arms  910 ,  912  in the proximal neck portion of the elongate body  905  as well as distal arms  920 ,  922  in the distal portion of elongate body  905 . In one embodiment, distal arm  920  includes a biased configuration wherein a distal tissue engaging surface  925  is adjacent to, and faces, a proximal tissue engaging surface  915  of the proximal arm  910 . Distal arm  922  also includes a biased configuration wherein a distal tissue engaging surface  927  is adjacent to, and faces, a proximal tissue engaging surface  917  of the proximal arm  910 . Such a fixation device may serve to dampen the strain upon the leaflets by allowing the fixation portions to move more freely with the valve during use, while providing force necessary to retain the leaflets in a joined configuration to treat disease. In the embodiment of  FIG. 9 , each proximal arm  910 ,  912  is shown to include tissue retention mechanisms, such as teeth  924 , disposed along its length. As discussed with regard to  FIGS. 4-7 , additional or alternate tissue retention mechanisms and patterns may be substituted herein consistent with this disclosure. 
       FIG. 10  is a side view of an embodiment of a fixation device  1000  formed from a unitary elongate body  1005  which has been apportioned along its thickness to provide a plurality of distal arms  1020 ,  1022 ,  1030 ,  1032 , each of which is biased to a closed configuration wherein at distal tissue engaging surfaces  1021 ,  1023 ,  1031 ,  1033  are oriented towards a tissue engaging surface of the proximal neck portion  1010  of the body  1050 . In one embodiment, connectors  1021 ,  1023  may be deployed to couple interior distal arms  1030 ,  1032  to exterior distal arms  1020 ,  1022  so that, when the exterior distal arms  1020 ,  1022  are spread, the interior distal arms  1030 ,  1032  are pulled open, allowing tissue to be disposed between the arms  1020 ,  1030 ,  1022 ,  1032  an the proximal neck portion  1010  of the body  1050 . As shown in  FIG. 10 , tissue retention mechanisms such as teeth  1011 ,  1013  may be strategically placed along the proximal neck portion  1010  and/or arms  1020 ,  1022 ,  1030 ,  1032  to secure tissue within the device  1000 . 
     The leaflet retaining devices such as those described in various embodiments above, may be used 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 fixation devices may be particularly useful for 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. 
     For example, the leaflet fixation device may be used for edge to edge repair of a cardiac valve including but not limited to a mitral valve. The mitral valve can be accessed from a remote surgical or vascular access point and the two valve leaflets may be brought together at a fixation point using the fixation device via endovascular or minimally invasive approaches. For example, the fixation device may be used to join the anterior leaflet and posterior leaflet of the mitral valve at any location of the leaflets between the anterolateral and posteromedial commissures of the valve. Multiple fixation devices may be used to couple the leaflets at various points of the valve. In some circumstances the fixation device may be used 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. 
     The fixation device may be delivered using a tool that is positioned near a desired treatment site and used to manipulate the fixation device, enabling the device to grasp the target tissue. In endovascular applications, the delivery tool may typically be a working catheter that is translated to the treatment site via a delivery catheter/guidewire system. In surgical applications, the delivery tool may typically a surgical instrument. 
     In one embodiment, the method includes the steps of advancing the delivery tool having a proximal end and a distal end to a location within a patient&#39;s body, wherein the delivery tool releasably carries the fixation device and is configured to translate the fixation device between its open and closed configuration to grasp leaflet tissue, and to release the leaflet tissue following positioning of the fixation device on the leaflets. 
       FIGS. 11A-11E  illustrate features of one embodiment of a delivery tool  1100  which may be used to deliver a fixation device  1150  to a treatment site. The delivery tool  1100  is shown to include a support arm  1120  comprising a proximal end  1101  and distal end  1103 , the distal end  1103  having an opening defining a sleeve configured to releasably accept the proximal neck portion  1110  of the fixation device  1150 . In some embodiments, for example, the proximal neck portion  1110  of the fixation device may include a slot which cooperates with a tab (not shown) internal to the sleeve to retain the proximal neck portion  1110  of the device within the sleeve during deployment. Following deployment, the tab may be withdrawn from the slot, freeing the device from the delivery tool. 
     The delivery tool  1100  further includes one or more spreader mechanisms, such as jaws  1152 ,  1154 . Each jaw  1152 ,  1154  is generally matched in shape to the curve of the fixation device  1150  to minimize the profile of the delivery tool. In one embodiment, the jaws  1152 ,  1154  comprise a curved shape to minimize the potential for interference between the distal end  1103  of the delivery tool and cardiac features, such as chordae tendinea and the like. In one embodiment, each jaw  1152 ,  1154  is pivotably mounted at pivot point  1156  of its distal end to the distal end  1103  of the support arm  1120  of the delivery tool  1100 . Guide cables  1122 ,  1124  may extend from the proximal end of the jaw to the distal end  1103  of the support arm  1120  of the delivery tool  1100 , wherein actuation of the drive cables, for example, for example, pulling the cables proximally through the sleeve, may pull the jaws  1152 ,  1154  away from a longitudinal axis defined by the delivery tool. In one embodiment, the distal arms of the fixation device  1150  are releasably coupled to the proximal ends of the jaws  1152 ,  1154  such that when the jaw is pulled away from the longitudinal axis of the delivery tool, the distal arm is also pulled away, creating a gap which may be used to grasp leaflet tissue. 
     For example,  FIG. 11B  illustrates the delivery tool  1100  supporting the fixation device  1150  in a partially open configuration, wherein the jaw  1154  is releasably coupled at its proximal end  1157  to the distal arm  1155  of the fixation device  1150 . Guide cable  1124  may be pulled into the support arm  1120  to open the jaw  1154  to create a gap G 1  for accepting leaflet tissue. The guide cable  1124  may then be released or otherwise actuated to allow the arm  1155  to return to its biased, closed configuration to capture leaflet tissue between the arm  1155  and the proximal neck portion  1110  of the fixation device  1150 . 
       FIG. 11C  illustrates the actuation of the second jaw  1152 , for example which may occur by manipulation of the guide cable  1122  through the support arm  1120  as described above. When the guide cable  1122  is pulled proximally through the support arm  1120 , the jaw  1152  opens. The distal arm  1159 , which is releasably coupled to the jaw  1152 , also is pulled away from the proximal neck portion  1110  of the fixation device  1150  by action of the jaw, generating a gap G 2  for capturing a second valve leaflet. Once the valve leaflet is positioned within the gap G 2 , the guide cable  1122  may be released or otherwise controlled to allow the distal arm  1159  to return to its biased configuration, capturing tissue between the arm  1159  and the proximal neck portion  1110  of the device  1150 . 
       FIG. 11D  is a close-up cross section of an example of a system for coupling the distal arm  1159  to the jaw  1152 . In one embodiment, as described above, the distal arm may have a coupler  1162  disposed at its distal end. The coupler may comprise, for example, a protuberance having a bore  1163  extending therethrough, with the bore sized to accept a distal end of the guide cable  1122 . In some embodiments, the guide cable  1122  may include a drive tube having a threaded coupler  1134  disposed on its distal end  1125 . The threads of the coupler may interact with threads or other features on the internal surface of the bore  1163  to secure the threaded coupler  1134  within the bore  1163 . In some embodiments, the drive tube may be rotatable, and rotation of the drive tube may translate the drive tube axially within the bore  1163 . Once the fixation device has been manipulated to grasp both anterior and posterior leaflets, actuation of the drive to may be performed to distally translate the drive tube out through bore  1163 , releasing the coupling between the arm  1159  of the fixation device and jaw  1152  of the delivery tool, and enabling removal of the delivery tool from the treatment site. 
     In some embodiments, the connection between the delivery tool and the fixation device may be formed to inhibit affixation of the fixation device during its placement, to facilitating positioning of the fixation device on the leaflets without tissue interference. For example,  FIG. 11E  is a close up view of one embodiment of a jaw  1152  of a delivery tool, including a sleeve  1170  disposed longitudinally along at least a portion of the length of the jaw. The sleeve  1170 , in one embodiment, provides a standoff which maintains a space between the tissue retention mechanisms and an opposing tissue engagement surface, to inhibit entry of the tissue retention mechanisms into tissue during positioning of the fixation device. A height H STANDOFF  of the sleeve  1170  may generally correspond to the protrusion distance of any tissue retention mechanism of a fixation device. 
       FIG. 11F , for example, illustrates a fixation device  1180  disposed upon the jaw portion  1152  of a delivery system. The fixation device  1180  is shown to include tissue retention features (e.g., teeth)  1183  disposed along edges of the device  1180  and oriented and protruding towards a tissue engaging surface  1185  of the fixation device  1180 . The sleeve  1170  is configured to at least partially inhibit entry of the teeth  1183 . For example, the sleeve may have a height that is equal to at least half of the extent of protrusion of the teeth  1183 . In some embodiments, the sleeve  1170  may include a bore  1187  extending therethrough, for example, to slidably accept a cable (not shown) that opens and closes the jaw of the delivery tool. It should be noted that, although a unitary sleeve is shown in  FIGS. 11E and 11F , alternative methods of inhibiting tissue affixation during placement of the fixation device, including but not limited to separate spacers disposed along the length of the jaw, shields disposed over the tissue retention mechanisms and the like are considered to be within the scope of this disclosure. 
       FIGS. 12A-12C  illustrate an alternate embodiment of a delivery tool  1200  that may be used to deliver a fixation device  1250  such as those described herein in various embodiments, to a treatment site. The delivery tool includes a proximal end  1201  and a distal end  1203 , and a pair of spreader arms  1230 ,  1232  rotatably disposed on the distal end  1203  of the delivery tool, wherein the spreader arms are operable to push the distal arms  1220 ,  1222  of the fixation device  1250  away from a longitudinal axis defined by the delivery tool to thereby generate a gap between the tool  1200  and the arms  1220 ,  1222  for corralling leaflet tissue. In some embodiments, the delivery tool may include a distal sleeve, configured to releasably carry the proximal neck portion  1201  of the fixation device to the treatment site. In various embodiments, each spreader arm may be rotatably coupled to the proximal end  1201  of the delivery tool, for example at pivot points  1211 ,  1213 , and adapted to move smoothly over an internal surface  1241 ,  1243  of the arms  1220 ,  1222 . For example, in one embodiment, each spreader arm  1230 ,  1232  may include a roller  1240 ,  1242  disposed on its distal end that enables the spreader arm to smoothly glide over the surfaces  1241 ,  1243  while providing a pushing force that acts against the biased configuration of the arms to generate the gap. It can be appreciated that the length of each spreader arm may vary depending upon the particular architecture of the fixation device but should be sufficient to allow the spreader arm to generate a gap that is capable of accepting leaflet tissue when rotated about its pivot point. 
     For example, referring now to  FIG. 12B , the delivery device is shown in a partially open position, wherein the spreader arm  1232  has been rotated across the surface  1241  of the distal arm  1222  to a position generally perpendicular to the axis of the delivery device. The rotation force of the spreader arm is sufficient to counteract the bias forces of the fixation device  1250 , causing the distal arm  1222  to be pushed away from the delivery tool  1200  and generating a gap G 1  between the tool  1200  and the distal arm  1222  for accepting tissue. When tissue has been corralled between the tool  1200  and the distal arm  1222 , the spreader arm  1232  may be rotated distally, removing the counteracting forces and allowing the distal arm  1222  to return to its biased configuration to capture tissue between the tool  1200  and the distal arm  1222 . 
       FIG. 12C  illustrates the delivery device in a partially open position, wherein the spreader arm  1230  has been rotated across the surface  1243  of the distal arm  1220  to a position generally perpendicular to the axis of the delivery tool  1200 . The rotation force of the spreader arm  1230  is sufficient to counteract the bias forces of the fixation device  1250 , causing the distal arm  1220  to be pushed away from the delivery tool  1200  and generating a gap G 2  between the tool  1200  and the distal arm  1220  for accepting tissue. When tissue has been corralled between the tool  1200  and the distal arm  1220 , the spreader arm  1230  may be rotated distally, removing the counteracting forces and allowing the distal arm  1220  to return to its biased configuration to capture tissue between the tool  1200  and the distal arm  1220 . 
     Once both leaflets are secured, the delivery tool may be removed, for example by releasing or otherwise expelling the proximal end of the fixation device  1250  from the delivery tool  1200 . 
       FIGS. 13A-13D  illustrate various structures of a heart  1300 , including a mitral valve  1320  comprising posterior and anterior leaflets  1322 ,  1324  supported by chordae tendinea  1325  which are controlled by papillary muscles  1326 . In the illustrated embodiment, a delivery catheter  1400  supports a delivery tool  1450  and may be used to navigate the delivery tool  1450  to a treatment site, for example below a mitral annulus  1340 . 
     In  FIG. 13A , the delivery tool  1450  is shown delivered through the atrium to the leaflets, although the disclosure is not limited to any particular delivery pathway. The rounded architecture of the delivery tool  1450  reduces the potential of interference between the chordae tendinea and the delivery tool.  FIG. 13B  illustrates the delivery tool  1450  following capture of a leaflet  1324  by the fixation device. Once one leaflet is captured, as shown in  FIG. 13C  the delivery tool  1450  may be used to pull leaflets  1324  towards leaflet  1322 , for example, until the two leaflets coapt. The delivery tool  1450  may then be operated to open and close the spreader mechanism to capture the second leaflet  1322  within the retention device. 
       FIG. 13D  is a magnified side view of the coupled leaflets shown in  FIG. 13C , following removal of the delivery tool. As shown in  FIG. 13D , following delivery, the fixation device  1350  is positioned such that the leaflets  1322 ,  1324  are securely captured between the proximal end  1310  of the fixation device  1350  and the arms  1352 ,  1354  of the fixation device  1350 .  FIG. 14  is a top down view of a mitral valve, following placement of a fixation device  1450  between a posterior leaflet  1402  and an anterior leaflet  1404 . 
     Accordingly, a unitary, lightweight leaflet clip is provided for use in securing valve leaflets for cardia repair procedures has been shown and described in various embodiments. With such an arrangement, the number and type of components involved in the leaflet clipping solution is reduced to a single, unitary component that leverages the resistive forces of shape memory material as a fixation mechanism, thereby reducing the overall weight of the fixation device and failure risks associated with chronic interaction between components. 
     As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” and/or “comprising,” or “includes” and/or “including” when used herein, specify the presence of stated features, regions, steps, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     As used herein, the conjunction “and” includes each of the structures, components, features, or the like, which are so conjoined, unless the context clearly indicates otherwise, and the conjunction “or” includes one or the others of the structures, components, features, or the like, which are so conjoined, singly and in any combination and number, unless the context clearly indicates otherwise. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about,” in the context of numeric values, generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure. Other uses of the term “about” (i.e., in a context other than numeric values) may be assumed to have their ordinary and customary definition(s), as understood from and consistent with the context of the specification, unless otherwise specified. The recitation of numerical ranges by endpoints includes all numbers within that range, including the endpoints (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     It is noted that references in the specification to “an embodiment,” “some embodiments,” “other embodiments,” etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether explicitly described, unless clearly stated to the contrary. That is, the various individual elements described herein, even if not explicitly shown in a particular combination, are nevertheless contemplated as being combinable or arrangeable with each other to form other additional embodiments or to complement and/or enrich the described embodiment(s), as would be understood by one of ordinary skill in the art. 
     The devices and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While various embodiments of the devices and methods of this disclosure have been described, it may be apparent to those of skill in the art that variations can be applied to the devices and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.