Patent Publication Number: US-2021161667-A1

Title: Percutaneous sling for papillary muscle approximation

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 62/942,779, filed Dec. 3, 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 and more particularly to implantable devices, systems, and methods for adjusting heart features. 
     BACKGROUND 
     Mitral insufficiency (MI) is a form of heart disease where the mitral annulus excessively dilates and the valve leaflets no longer effectively coapt during systolic contraction. Regurgitation occurs during ventricular contraction and cardiac output decreases. 
     An annuloplasty procedure may be performed to restore the physiological form and function of the mitral annulus. Annuloplasty procedures may involve surgically implanting a ring around the mitral annulus to restore a diameter of the patient&#39;s mitral annulus to that of a healthy state where the valve leaflets properly coapt and mitral regurgitate flow is minimized. Additionally, sub-valvular repair procedures such as repositioning of papillary muscles or repairing chordae within the left ventricle may be performed. 
     Due to the invasive nature of the surgical approaches to mitral valve repair, several transcatheter techniques have been developed to emulate surgical approaches. Because delivery catheters that carry mitral valve or sub-valvular components may extend up to 52″ in length, it can be challenging to accurately transport and deliver components to a treatment site. 
     SUMMARY 
     One general aspect includes an implant including a sling catheter having a first opening and a second opening, the first opening and second opening extending through a wall of the sling catheter, a first anchor configured to be disposed adjacent and external to the first opening of the sling catheter, a second anchor configured to be disposed adjacent and external to the second opening of the sling catheter and a suture, extending through a lumen of the sling catheter, the suture having a first end coupled to the first anchor, and a second end coupled to the second anchor. 
     In various embodiments, the first opening and the second opening are two of a plurality of spaced apart openings of the sling catheter, where the spaced apart openings may be evenly spaced or variably spaced. The sling catheter may be comprised of a polytetrafluoroethylene tube. At least one of the first opening or the second opening may be oriented towards a papillary muscle. The first opening and the second opening may be aligned along a common longitudinal axis of the sling catheter or disposed along different longitudinal axes of the sling catheter. The first anchor and the second anchor may be two of a plurality of anchors of the implant, and each anchor may be biased towards a configuration that inhibits return of the anchor into the sling catheter. 
     According to another aspect, a delivery system includes a first catheter having a proximal end, a distal end and a lumen extending from the proximal end to the distal end, where a portion of the distal end of the first catheter includes a sling having a plurality of spaced apart openings extending through a first catheter wall. The system may include a second catheter having a proximal end, a distal end, and a delivery lumen extending from the proximal end to the distal end, the distal end of the second catheter including a delivery port that extends through a second catheter wall. The second catheter may be translatably disposed within the lumen of the first catheter to enable alignment of the port with one or more of the plurality of spaced apart openings of the sling. The delivery system may also include a plurality of anchors and a push tube, translatably disposed within the delivery lumen and configured to advance at least one of the plurality of anchors through the delivery lumen and through the delivery port. 
     In various embodiments, the sling of the first catheter may be formed of a polytetrafluoroethylene tube. The sling may have a higher flexibility than the second catheter. The outer diameter of the sling may be between 1 millimeters (mm) and 12 mm, may have a length of the sling between 1 centimeter (cm) to 35 cm and the plurality of spaced apart openings may be spaced at least 2 mm apart. In some embodiments, the plurality of anchors may be coupled via one or more sutures. In some embodiments, a cinch mechanism may be configured to reduce spacing between the plurality of anchors, where in some embodiments the cinch mechanism may be configured to detach the sling from the first catheter. The cinch mechanism may be configured to bind at least a portion of the suture to at least one anchor. 
     In some embodiments, each of the plurality of anchors may comprise a first configuration enabling translation through the second catheter and delivery port, and a second configuration that inhibits translation through the delivery port, and the second catheter may retain the plurality of anchors in the second configuration. In some embodiments, the plurality of spaced apart openings of the sling may be aligned along a common longitudinal axis of the first catheter or may be disposed along different longitudinal axes of the first catheter. The plurality of spaced apart openings may be evenly spaced or a spacing of plurality of spaced apart openings may vary. For example, spacing of openings in regions expected to be contacting papillary muscles may be closer, enabling adequate flexibility in number and position of anchors placed. The delivery system may include a cinching mechanism for tightening the sutures. 
     According to another aspect, a method of sub valvular repair includes advancing a catheter system to a left ventricle, the catheter system including a sling catheter having a plurality of openings extending through a distal wall of the sling catheter and a delivery catheter, translatably disposed within the sling catheter, the delivery catheter having a distal port extending through a wall of the delivery catheter. The method includes orienting the plurality of openings towards papillary muscles and advancing a first anchor towards the distal port of the delivery catheter, the first anchor having a linear configuration enabling translation of the first anchor through the delivery catheter. The method includes aligning the distal port with a first opening of the sling catheter and pushing the first anchor through the distal port and the first opening into first papillary tissue, the first anchor assuming a biased configuration that inhibits return of the first anchor into the first opening when the first anchor is pushed from the delivery catheter and advancing a second anchor towards the distal port of the delivery catheter, the second anchor having the linear configuration during translation through the delivery catheter, the second anchor may be coupled to the first anchor by a suture. The method includes aligning the distal port with a second opening of the sling catheter. The method includes pushing the second anchor through the distal port and the second opening into second papillary tissue, the second anchor assuming the biased configuration that inhibits return of the second anchor into the second opening when the second anchor is pushed from the delivery catheter and tightening the suture to draw the first anchor and the second anchor together to adjust a spacing between the first papillary tissue and the second papillary tissue. 
     In some embodiments, the method may further include: binding one or more portions of the suture to at least one anchor, detaching at least a portion of the sling catheter, and removing the catheter system from the left ventricle. 
     With such an arrangement, an implant and method of delivery is disclosed which enables non-invasive sub-valvular repair. 
    
    
     
       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: 
         FIG. 1  is a diagram of a portion of a heart in which delivery catheters such as those disclosed in various embodiments herein may be deployed; 
         FIGS. 2A and 2B  illustrate several embodiments of a sling catheter in accordance with the present disclosure; 
         FIG. 3  illustrates one embodiment of an anchor delivery catheter in accordance with various aspects of the present disclosure; 
         FIG. 4  is a cross-sectional view of a distal end of the sling catheter, anchor catheter, and push tube as disclosed herein in one embodiment; 
         FIGS. 5A-5E  illustrate examples of steps that may be performed to deploy anchors to papillary tissue for sub-valvular repair using one embodiment of the delivery system disclosed herein; and 
         FIGS. 6A and 6B  illustrate one embodiment of an anchor that may be used in embodiments disclosed herein; 
         FIGS. 7A and 7B  illustrate one embodiment of an anchor that may be used in embodiments disclosed herein; 
         FIGS. 8A and 8B  illustrate one embodiment of an anchor that may be used in embodiments disclosed herein; 
         FIGS. 9A and 9B  illustrate one embodiment of an anchor that may be used in embodiments disclosed herein; 
         FIG. 10  is a diagram of a portion of a heart following sub-valvular repair as disclosed in one embodiment herein. 
     
    
    
     DETAILED DESCRIPTION 
     An implant system and method of delivery includes a catheter system including a sling catheter having a plurality of distal openings and an anchor delivery catheter, disposed within the sling catheter and having a distal port. Suture coupled anchors may be sequentially delivered by the anchor delivery catheter to a cardiac treatment site by aligning the port of the anchor delivery catheter with different openings of the sling catheter and pushing the anchor through the port and the sling catheter to embed the anchor into cardiac tissue such as tissue of a papillary muscle. Each anchor may have a linear configuration for translation within the delivery catheter and a biased configuration that inhibits its reentry into the sling catheter once deployed. Once all anchors are deployed, the suture may be tightened, the anchored portion of the sling catheter may be detached, and the catheter system withdrawn. Such a system may be used to bring tissue features of the heart closer together, for example, for valvular and/or sub-valvular repair procedures such as annuloplasty and repair, replacement and/or repositioning of a valve leaflet, a papillary muscle, or chordae to improve valve function. 
     These and other beneficial aspects of a system for sub-valvular repair are described in more detail below. It should be noted that, although embodiments of the present disclosure may be described with specific reference to papillary muscles, the principles disclosed herein may be readily adapted to 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. 
       FIG. 1  is a diagram of a left chamber of a heart  100 , including a left atrium  110  separated from a left ventricle  130  by a mitral valve  120 . The mitral valve  120  includes an anterior leaflet  122   a  and a posterior leaflet  122   b  which are attached in a healthy heart to respective papillary muscles  134   a ,  134   b  via chordae tendineae  132   a ,  132   b . The papillary muscles  134   a ,  134   b  contract to prevent inversion or prolapse of the leaflets  122   a ,  122   b  on contraction of the left ventricle  130 . A mitral annulus  115  comprises a fibrous ring that, in a healthy heart is saddle shaped and of a diameter to enable the valves to close, or coapt, during systolic contraction. 
     In a diseased heart, one or more of the chordae tendineae  132   a ,  132   b  may be stretched or ruptured, resulting in a flailing leaflet  122   a ,  122   b  that no longer effectively closes, resulting in regurgitation. Alternatively, or in conjunction, the mitral annulus  115  may become stretched or deformed, and the valves may also fail to close as a result. 
     To repair the heart failure condition, repair components may be transluminally deployed to the heart  100 . In  FIG. 1 , a delivery system  150  as disclosed herein is shown advanced through a femoral artery to the aorta  140  and into the left ventricle  130  for transfemoral retrograde delivery of repair components. Depending upon the heart feature that is to be repaired it is appreciated that the present disclosure is not limited by the manner in which the delivery system is introduced to the heart  100 . For example, to deliver repair components to a left atrium, a transapical or transseptal delivery pathway may be used with embodiments of the delivery catheter and system disclosed herein. 
     In one embodiment, the delivery system  150  may include a plurality of nested catheters having a steerable distal end  155  to facilitate navigation of repair components into the left ventricle. According to one aspect, as described in more detail below, the delivery system  150  includes a sling catheter  160  including a detachable distal portion comprising a tubular sling  175  having a plurality of openings  176  extending therethrough. 
     During delivery, a distal guidewire (not shown) disposed within the sling catheter  160  may assist with transluminal navigation. For example, as shown in  FIG. 1 , the distal guidewire may deliver the sling  175  into the left ventricle  130 , pushing the sheath against the wall of the left ventricle around the base of the papillary muscles  134   a ,  134   b . An anchor delivery catheter translatably disposed within the sling  175  may advance one or more suture coupled anchors through openings  176  of the sling  175  into papillary tissue. Following anchor deployment, the suture may be cinched to draw together the papillary muscles, to approximate a healthy papillary structure where leaflets  122   a ,  122   b  are drawn together to improve cardiac function. As will be now described in more detail below, the sling  175  may then be detached and remain within the left ventricle to retain the papillary muscles in their restructured state. 
       FIGS. 2A, 2B and 3  illustrate examples of catheters that may form the nested catheters of the delivery system  150  ( FIG. 1 ). For example,  FIG. 2A  illustrates a top down perspective view of one embodiment of the sling catheter  160 . In some embodiments, the sling catheter  160  may include a tubular body having a proximal end  215 , a distal end  205 , and an elongate body  210  extending therebetween. A lumen  212  may extend from the proximal end through the distal end of the sling catheter  160  along axis ‘A’ in  FIG. 2A . A connector  225  may be disposed at the proximal end  215 , enabling the sling catheter  160  to be releasably coupled to a connector of a steerable catheter that may be used to guide the sling catheter  160  into position within the cardiac cavity. The connector  225  may take any of a variety of forms, for example including but not limited to a screw connector, a snap fit connector, a Luer connector, etc. Accordingly, the disclosure is not limited to the mechanism for coupling the sling catheter  160  to a steerable catheter. 
     In one embodiment, the sling catheter  160  is formed of a pliant material such as a polytetrafluoroethylene (PTFE) tube or other various materials suitable for implantable devices. The sling catheter  160  may comprise varying properties and/or materials along the length of the sling  175  or around the cross-sectional diameter of the sling  175  to achieve the properties desired (e.g., abrasion resistance, strength, etc.). The sling catheter  160  may comprise a composite material, such as fibers of one material embedded into a matrix of a second material. Some examples of materials (in addition to those already noted) may include polyether-polyurethane (PE-PUR copolymers), poly(styrene-isobutylene-styrene) (SIBS) tri-block polymers, polyisobutylene urethane copolymers (PIB-PUR), polyisobutylene (PIB), polyethylene or other similar materials. In some embodiments, the length of the sling catheter  160  may range from between 24″-52″, and more particularly between 42″-46″. In one embodiment, the inner diameter of the sling catheter  160  may range between 0.75 mm-11.5 mm, and the outer diameter may range between 1 mm-12 mm or more. In an example of an embodiment, an inner diameter may be, for example 28Fr and the outer diameter may be 32Fr. 
     As described, in some embodiments a distal end  205  of the sling catheter  160  includes a plurality of openings  176 . According to one aspect, the distal portion  205  of the sling catheter  160  that includes the plurality of openings  176  is referred to as a ‘sling’. The length of the sling may range from between 1 and 35 cm. For example, longer slings are envisioned which may wrap circumferentially multiple times around the papillary muscles (2-3 or more) within the left ventricle. In some embodiments, the plurality of openings include spaced apart openings having a cross section diameter selected to enable an anchor to pass through the opening into cardiac tissue. For example, the cross-sectional diameter of openings may range between 0.50 mm and 10 mm. In some embodiments, the openings  176  are evenly spaced apart. In alternate embodiments, the spacing between openings may vary, for example, to provide closer openings at areas of the sling that may be positioned adjacent to papillary muscles and may have increased spacing over areas of the sling that may be generally disposed between papillary muscles. In some embodiments, the plurality of spaced apart openings may be aligned on a common axis that is parallel to the central axis A, as illustrated in  FIG. 2A . In alternate embodiments, the plurality of spaced apart openings may not be aligned on a common axis but may be distributed along different linear axes of the wall of the sling catheter  160 . For example,  FIG. 2B  illustrates an embodiment of a sling catheter  275  having openings  276  that are variably spaced and distributed along different linear axes of the sling catheter body. In other embodiments, it is contemplated that the sling catheter  160  may in fact have no pre-formed openings; but, rather, the anchor (which is delivered through the anchor delivery catheter), punctures through the sling catheter  160  and into tissue at locations decided upon by the physician during the procedure. In this case, the opening in the sling catheter  160  for the suture would be defined by the size of the suture(s). 
       FIG. 3  is a side view perspective of one embodiment of a steerable catheter that may be translatably disposed within the sling catheter  160  ( FIG. 2A ), or sling catheter  275  ( FIG. 2B ). For example, the steerable catheter may include an anchor delivery catheter  300  comprising a steerable shaft  310  extending from a distal end  305  to a proximal end  315 . The proximal end  315  of the anchor delivery catheter  300  may include a handle  325  having a dial  330 , or other control mechanisms that are configured to steer the distal end  305  of the catheter  300 . For example, the steerable shaft  310  may comprise embedded pull cables which may be coupled to mechanisms in the handle  325  configured to deflect the distal end  305  of the catheter  300  as it travels through the lumens of arteries or veins into the left ventricle. It is appreciated that, although a dial  330  is shown, alternative steering control mechanisms may include, for example, thumbwheels, dials, knobs, switches, and the like and the disclosure is not limited by the manner of steering the anchor delivery catheter  300 . 
     According to one aspect, the shaft  310  of the anchor delivery catheter  300  comprises a generally tubular structure having a lumen extending therethrough. The lumen has a diameter configured to enable translation of an anchor from the proximal end  315  to the distal end  305  of the catheter  300 . In one embodiment, the distal end  305  of the anchor delivery catheter  300  includes one or more anchor ports, such as port  340 . The port  340  is sized to allow an anchor to be expelled from the lumen of the anchor delivery catheter  300 . In some embodiments, the diameter of the anchor port  340  relates to the diameter of openings of the associated sling catheter (e.g., such as openings  176  of the sling catheter  160  of  FIG. 2A ). In some embodiments, the diameter of the anchor port  340  is at least equal to the diameter of the openings in the associated sling catheter to facilitate passage of the anchor, although this is not a requirement. 
     In one embodiment, the anchor delivery catheter  300  may comprise a composite of layers of thermoplastic elastomer (TPE), for example PEBAX provided by ARKEMA corporation of Colombes, France. Alternatively, nylon, polyurethanes, polyester, silicone, or other similar materials may be used to provide thin walls that may be extruded and layered over braided wires or coils for tensile and hoop strength, although the disclosed system is not limited to any particular material composition for the anchor delivery catheter  300 . In some embodiments, the length of the anchor delivery catheter  300  may range from between 24″-52″, and more particularly between 42″-46″. In one embodiment, the inner diameter may range between 0.25 mm to 11 mm. The outer diameter is related to the inner diameter of the sling catheter  160  and is sized to enable translation of the anchor delivery catheter  300  freely within the sling catheter  160 . For example, the outer diameter may range between 0.75 mm to 11.5 mm 
     In some embodiments, the handle  325  may comprise a coupler  350  configured to accept a push tube (such as push tube  355 ) or a guidewire, enabling the push tube  355  or guidewire to advance between the proximal end  315  and distal end  305  of the anchor delivery catheter  300 . 
     Although the anchor delivery catheter  300  has been described as a steerable catheter, in alternate embodiments the anchor delivery catheter  300  may be a flexible catheter and steering of the sling catheter  160  into position may be achieved using a steerable guidewire. 
       FIG. 4  is a cross section of a distal end  405  of a delivery system  400  including a sling catheter  410  and an anchor delivery catheter  420  translatably disposed within the sling catheter  410 . Delivery system  400 , in various embodiments, may be formed similarly to delivery systems described above. The sling catheter  410  is shown to include a plurality of spaced apart openings  476 . The anchor delivery catheter  420  is shown to include an anchor port  440 . In one embodiment, the delivery system delivers anchors by aligning the port  440  of the anchor delivery catheter  420  with one of the openings  476  of the sling catheter  410 . An anchor  450  may be advanced through a lumen of the anchor delivery catheter  420  towards the port  440 , for example by a push tube  430  that is translatably disposed within the lumen of the anchor delivery catheter  420 . 
     The anchor  450  may take a variety of forms. In some embodiments, the anchor  450  may be comprised of a shape memory material, for example a copper-aluminum-nickel, a nickel-titanium (NiTi) alloy, or other alloy of zinc, copper, gold and/or iron. In some embodiments the anchor  450  comprises a generally linear configuration facilitating translation through the lumen of the anchor delivery catheter  420  and biased towards an expanded configuration that inhibits translation of the anchor through the opening  476 /port  440 . For example, the anchor  450  is shown to include a talon  423   a  disposed at a distal end, and a suture coupler including an eyelet  423   b  disposed at the proximal end. 
     A suture  460  may be coupled to the anchor eyelet  423   b . In some embodiments, the suture  460  may be tied to the eyelet  423   b  of the anchor  450 , and in some embodiments the suture  460  may loop through the eyelet  423   b , enabling cinching of anchors  450  as described in  FIGS. 5A-5E . 
     The suture may be formed of any of a variety of biocompatible materials, including nylon, polyester, polymeric, or metallic wire or the like. In some embodiments, the suture may be braided and/or manufactured of two or more materials. Some other examples of materials (in addition to those noted) may include polypropylene, ultra-high molecular weight polyethylene, polyetheretherketone, polytetrafluoroethylene (PTFE), silk, or combination thereof. In some embodiments, the suture may be comprised of metals such as stainless steel and nitinol. For example, the suture may comprise a pre-shaped, heat-set Nitinol spring/braid/construction (i.e., Nitinol extension spring, spiral extensions, etc.) that are self-collapsing as it is deployed from the catheter around the papillary muscles, to bring the papillary muscles closer together. 
       FIGS. 5A-5E  comprise top down views of a delivery system  500  that has been delivered into a left ventricle. In  FIGS. 5A-5E , the sling catheter  510  and anchor delivery catheter  520  are shown in cross section. In some embodiments, the sling catheter  510  is looped around the papillary muscles PM 1 , PM 2 . In some embodiments, the sling catheter is looped around the base of the papillary muscles PM 1 , PM 2 . In alternate embodiments, the sling catheter  510  is positioned anywhere between the base of the papillary muscles PM 1 , PM 2  and the mid-section of the papillary muscles PM 1 , PM 2 . It is appreciated that positioning the sling catheter  510  between the midpoint and base of the papillary muscles may reduce the potential that anchors interfere with the chordae tendinea. 
     Once positioned, the sling catheter  510  may be contracted to engage an exterior surface, such an interior circumferential external surface, of the sling catheter with the papillary muscles PM 1 , PM  2 . The sling catheter  510  may be advantageously positioned so that at least a portion of the openings  576   a - 576   k  are oriented towards the papillary muscles PM 1 , PM 2 , ensuring that anchors that are expelled from the delivery system  500  may affix to papillary tissue.  FIG. 5A  illustrates anchor  550  advanced to opening  576   a  by a push tube  530 . The anchor  550  is coupled to a suture  560 , which may be threaded over the push tube  530  back to the proximal end of the delivery system  550  (as shown in  FIG. 4 ), or alternatively may be threaded through the push tube  530  as shown in  FIG. 5A . In the embodiment of  FIG. 5A , the anchor  550 , which provides the first anchoring of the sling catheter  510 , is shown tied to the anchor  550 . The push tube  530  continues to advance, pushing the anchor  550  through the port  540  of the anchor delivery catheter and through the opening  576   a  to deploy the anchor  550  into tissue of the papillary muscle PM 1 . 
       FIG. 5B  illustrates deployment of a second anchor  552  by the delivery system  500 . As shown, the first anchor  550  has been deployed and resumed its biased, expanded configuration which inhibits it being withdrawn back into the opening  576   a  of the sling catheter  510 . A surgeon may choose any of the openings  576   a - 576   k  of the sling catheter  510  for deploying anchor  552 , and  FIG. 5B  illustrates that anchor  552  is expelled through the port  540  of the anchor delivery catheter  520  and opening  576   e  of the sling catheter following proximal translation of the anchor delivery catheter  520  to align port  540  with opening  576   e . Anchor  552  is then forwarded into papillary tissue PM 2  by action of the push tube  530 . 
       FIG. 5C  illustrates the delivery system  500  following deployment of anchor  550  and anchor  552 , each of which has returned to a biased configuration inhibiting return of the anchor into the respective openings  576   a ,  576   e . In  FIG. 5C , port  540  of anchor delivery catheter  520  has been proximally withdrawn to align port  540  with opening  576   h  of sling catheter  510 , and push tube  530  is shown advancing anchor  554  to the port  540 /opening  576   h  to deploy the anchor  554  into tissue of papillary muscle PM 2 . In  FIG. 5D , it can be seen that delivery system  500  has deployed anchor  554  into tissue, the anchor delivery catheter  520  has been proximally withdrawn to align port  540  with opening  576   k , and push tube  530  has advanced anchor  556  through the port  540  and opening  576   k  towards papillary tissue PM 1 . Suture  560  couples all four anchors  550 ,  552 ,  554 , and  556 , and the biased configuration of the anchors  550 ,  552 ,  554 , and  556  inhibits their return into the sling catheter  510 . 
     Accordingly, at this point the anchor delivery catheter may be withdrawn, and the proximal end of the suture  560  pulled proximally, or otherwise cinched, to draw the anchors, and the papillary muscles PM 1 , PM 2  more closely together. For example,  FIG. 5E  illustrates sling catheter  510  following cinching of suture  560 , wherein it can be seen that the papillary muscles PM 1  and PM 2  have been drawn together by the cinching action. Anchors  550 ,  552 ,  554 , and  556 , while drawn towards respective openings  576   a ,  576   e ,  576   h , and  576   k  are inhibited from being drawn back into the sling catheter by their biased, expanded configuration. Once the suture  560  is tightened, the suture may be secured to the distal end of the sling catheter  510  to retain the cinched configuration of the sling catheter  510 , for example using a resistive weld  565  or the like, the distal end of the sling catheter  510  may be detached at point  566 , for example using cauterization or other means, and the remainder of the delivery system may be removed from the cardiac treatment site. Although  FIGS. 5A-5E  shows openings  576   a ,  576   e ,  576   h , and  576   k  utilized for delivering respective anchors, it should be appreciated that more or fewer openings  576   a - 576   k  may be utilized to effectuate the desired change to the papillary muscles PM 1 , PM 2 . 
     Various methods of detaching the sling catheter may be employed. For example, an electrical current may be delivered to resistively heat a localized region of the catheter causing it to detach under a little tension or torsion. Such a sheath could include the electrical conductors within the wall of the removable portion of the sheath for this purpose. In other embodiments, the sling portion may be mechanically detached, e.g., using a push-rod that engages and causes it to “break away” from the removable portion, or a threaded joint may be provided between the sling catheter and the sling portion of the sling catheter, and the two portions may be detached by rotating the sling catheter to release the threaded portions. In still other embodiments, an energy source may be advanced through the lumen of the delivery catheter, such as a laser, to “cut” the two portions, leaving the sling behind. 
     It should be noted that although delivery of four anchors has been shown and described, sub-valvular improvement may be realized with as few as two anchors, or as many anchors as there are openings in the sling catheter, and/or, as many anchors that may be pushed through openings or walls of the sling catheter. Accordingly, the disclosure is not limited to the use of any particular number of anchors. 
     In addition, although the diagrams have shown an anchor with extended tines, the present invention is not limited to the use of a particular anchor, but rather may use any form of anchor that may travel freely within a lumen but inhibit return to the lumen following deployment. For example,  FIGS. 6A-9B  illustrate various embodiments of anchors that may be suitable for this purpose.  FIG. 6A , for example, illustrates an anchor  600  in a linear configuration for translation within a lumen, and  FIG. 6B  illustrates the anchor  600  in an expanded configuration, wherein tines of the anchors extend radially outward.  FIG. 7A  illustrates a loop anchor  700  in a linear configuration and  FIG. 7B  illustrates the loop anchor in the expanded configuration.  FIG. 8A  illustrates a helical anchor  800  in a linear configuration and  FIG. 8B  illustrates the helical anchor as deployed, where the turns of the helical anchor would capture the edges of the port/openings to inhibit return of the anchor  800  into the sling catheter. The helical anchor may be incompressible (such that its diameter does not change when pushed through the catheter), for example, comprised of MP35N or stainless steel, or may be formed of a shape-memory material such as Nitinol that self-expands when released from the catheter. 
       FIG. 9A  illustrates a twisted anchor  900  in a linear configuration, and  FIG. 9B  illustrates the twisted anchor  900  in a deployed profile. The tine anchor  600 , loop anchor  700  and twisted anchor  900  may each be formed of a memory-based material biased towards their expanded configurations, and/or may return to their biased configuration in response to body heat. In any of the various embodiments, the anchors may be comprised of stainless steel, nitinol, or the like, and may include a sharpened distal end and/or barbs disposed over portions of the anchor bodies to secure the anchor to a treatment site. The anchor may range from about 2 mm to about 15 mm in total axial length and from about 0.2 mm or less to 3 mm or more in diameter. However, other embodiments may be used depending upon the anchoring purpose, and thus the disclosure is not limited to a particular form of anchoring. 
       FIG. 10  is a diagram of the heart  100  of  FIG. 1  following sub-valvular repair as disclosed in  FIGS. 5A-5E . As shown in  FIG. 10 , the sling catheter  510  remains disposed about the papillary muscles  134   a ,  134   b . The sling catheter  510  has been cinched using anchors and sutures and restrained in the cinched configuration by weld  565 , holding the papillary muscles together and pulling together the leaflets  122   a ,  122   b  of the mitral valve  120  to restore cardiac function. 
     Accordingly, a system and method for sub-valvular repair has been shown and described. Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the claims, the principles and the novel features disclosed herein. The word “example” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as an “example” is not necessarily to be construed as preferred or advantageous over other implementations, unless otherwise stated. 
     Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features can be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination can be directed to a sub-combination or variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. 
     It will be understood by those within the art that, in general, terms used herein are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
     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.