Abstract:
Medical devices for attaching suture to tissue and that provides reliable and complete closure of perforations and increases the versatility of the device for various other procedures. Embodiments of the medicals devices include a tissue anchor having a crossbar with opposing ends and structure for slidably receiving a suture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/120,220 filed on Dec. 5, 2008, entitled “TISSUE ANCHORS FOR PURSE-STRING CLOSURE OF PERFORATIONS” the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present invention relates generally to tissue anchors for connecting a suture to tissue, such are for using tissue anchors and suture to close perforations in tissue. 
       BACKGROUND 
       [0003]    Perforations in bodily walls may be naturally occurring, or formed intentionally or unintentionally. In order to permanently close these perforations and allow the tissue to properly heal, numerous medical devices and methods have been developed employing sutures, adhesives, clips, staples and the like. One class of such devices is commonly referred to as tissue anchors (T-anchors) or visceral anchors. An exemplary tissue anchor is disclosed in U.S. Pat. No. 5,123,914, the entire contents of which are incorporated by reference herein. Such tissue anchors have been very successful in medical procedures requiring tissue wall mobilization or wall apposition. 
         [0004]    Tissue anchors have also been successfully used in closing perforations, but are not without their drawbacks. For example, when a series of anchors are placed around a perforation, all of the individual sutures connected to the anchors must be collected and connected together. It can often be difficult to properly tension each of the individual sutures to ensure proper approximation of the tissue around the perforation and complete closure thereof. This is especially critical within the gastrointestinal tract, where the travel of bacteria laden fluids outside of the tract may cause unwanted and sometimes deadly infection. 
       BRIEF SUMMARY 
       [0005]    The present invention provides medical devices for attaching suture to tissue and that provides reliable and complete closure of perforations and increases the versatility of the device for various other procedures. One embodiment of a tissue anchor for connecting a suture to tissue, constructed in accordance with the teachings of the present invention, generally comprises a crossbar and a strand. The crossbar has first and second opposing ends and defines a longitudinal axis. The crossbar is defined by a tubular wall having an aperture between the first and second ends. The strand has first and second opposing ends connected to the first and second opposing ends of the crossbar, respectively. The strand makes a revolution to define a loop. The strand and its loop project through the aperture and away from the longitudinal axis. The loop is sized to slidably receive the suture therethrough. 
         [0006]    According to more detailed aspects of this embodiment of the tissue anchor, the strand has a diameter less than about 50% of a diameter of the crossbar. The strand preferably has a diameter in the range of about 0.2 mm to about 0.35 mm, while the crossbar has a diameter in the range of about 0.5 mm to about 1.1 mm. The loop has an apex located about 0.35 mm or greater away from the crossbar. The loop defines a cross-point where the ends of the strand cross each other, and the cross-point is preferably positioned radially outside the outer surface of the crossbar. The strand is flexible, and the aperture is sized to permit the loop to travel longitudinally along the strand. The aperture preferably extends a longitudinal distance in the range of about 0.4 mm to about 3.0 mm, while the crossbar typically has a length in the range of about 3.0 mm to about 10.0 mm. The strand may be a metal wire, and is preferably coated with a low-friction material. 
         [0007]    Another embodiment of a tissue anchor for connecting a suture to tissue, constructed in accordance with the teachings of the present invention, generally comprises a crossbar and a strand. The crossbar has first and second opposing ends and defines a longitudinal axis. The cross bar is defined by a tubular wall having first and second apertures between the first and second ends, the first and second apertures being longitudinally spaced apart. A flexible suture has first and second opposing ends connected to the first and second opposing ends of the crossbar, respectively. The suture extends through the first and second apertures and projects away from the crossbar between the first and second apertures to define a loop between the suture and the crossbar. 
         [0008]    Yet another embodiment of a tissue anchor for connecting a suture to tissue, constructed in accordance with the teachings of the present invention, generally comprises a crossbar and a flange. The crossbar has first and second opposing ends and defines a longitudinal axis. The flange is connected to the crossbar between the first and second ends and extends away from the longitudinal axis. The flange has a thickness less than a diameter of the crossbar. The flange defines a hole sized to receive the suture therein. According to more detailed aspects of this embodiment of the tissue anchor, an outer end surface of the flange follows a curved shape. Preferably, the crossbar and flange are unitarily and integrally formed. The crossbar and flange are optionally molded from a resorbable material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings: 
           [0010]      FIG. 1  is a front view of one embodiment of a tissue anchor constructed in accordance with the teachings of the present invention; 
           [0011]      FIG. 2  is a cross-sectional view taken about the line  2 - 2  in  FIG. 1 ; 
           [0012]      FIG. 3  is a front view of another embodiment of a tissue anchor constructed in accordance with the teachings of the present invention; 
           [0013]      FIG. 4  is a front view of yet another embodiment of a tissue anchor constructed in accordance with the teachings of the present invention; 
           [0014]      FIG. 5  is an end view taken of the tissue anchor depicted in  FIG. 4 ; 
           [0015]      FIG. 6  is a plan view schematically depicting a medical device constructed in accordance with the teachings of the present invention; 
           [0016]      FIG. 7  is a cross-sectional view of the medical device depicted in  FIG. 6 ; 
           [0017]      FIG. 8  is a schematic view of the medical device similar to  FIG. 6  but showing the medical device closing a perforation; and 
           [0018]      FIG. 9  is a cross-sectional view of the medical device as depicted in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Turning now to the figures,  FIGS. 1-2  depict a tissue anchor  20  constructed in accordance with the teachings of the present invention. The anchor  20  is utilized to connect a suture  22  to tissue, such as for closing a perforation  10  in a bodily wall  12  (see, e.g.,  FIGS. 6 to 9 ) or for use in other procedures. The anchor  20  generally includes a crossbar  24  having opposing ends  26  and  28  and defining a longitudinal axis  14 . The crossbar  24  is preferably elongated, but may take any form suitable for connecting the suture  22  to the bodily wall  12 . A strand  30  is connected to the crossbar  24  and is configured to form a loop  32 . As best seen in  FIG. 2 , the crossbar  24  is constructed of a cannula having a tubular wall  34  defining a lumen  36 . An elongated aperture  38  is formed in the tubular wall  34 , and the strand  30  passes through the aperture  38 . The ends of strand  30  are secured within the lumen  36  of the cannula by welds  44 . It will be recognized by those skilled in the art that the strand  30  may be secured to the crossbar  24  using any now known or hereinafter developed attachment means, including mechanical fasteners, adhesives or various welding or soldering techniques. Similarly, the strand  30  may have sufficient rigidity such that its ends do not need to be directly attached to the crossbar, as the formation of loop  32  projecting through the aperture  38  can be enough to retain the strand  30  within the crossbar  24 , and/or the ends of the strand  30  may simply be bent or otherwise deformed to keep them within the crossbar  24  and prevent them from passing through the aperture  38 . 
         [0020]    The strand  30  is preferably formed from a metal wire, including single filament and multi-filament wires, and wound and braided wires, although the strand  30  can have other constructions such as suture material, plastic strings, rope and the like. As best seen in  FIG. 1 , the strand  30  is structured to include a revolution thereby defining a loop  32  through which the suture  22  passes. The loop  32  is positioned longitudinally in-line with the elongated aperture  38  so that it projects through the aperture  38  and away from the longitudinal axis  14 . Accordingly, it will be seen that the strand  30  and its loop  32  are flexible and may adjust its shape and orientation based on how the suture  22  is being tensioned. The size of the elongated aperture  38  and the flexibility of the strand  30  allow the loop  32  to travel longitudinally along the length of the strand  30 . The loop  32  defines an apex A which is preferably located about 0.35 mm or greater away from the crossbar  24 . The loop  32  also defines a cross-point CP where the ends of the strand  30  cross each other. The cross-point CP is preferably positioned radially outside the outer surface of the crossbar  24  including radially outside the side walls of the aperture  38 , but also preferably as close to the crossbar  24  as possible. The aperture  38  preferably extends a longitudinal distance in a range of about 0.4 mm to about 3.0 mm, while the crossbar  24  typically has a length in the range of about 3.0 mm to about 10.0 mm. The strand preferably has a diameter less than about 50% of a diameter of the crossbar  24 , and most preferably less than about 35%. The strand  30  preferably has a diameter in the range of about 0.20 mm to about 0.35 mm, and most preferably about 0.254 mm. The crossbar  24  preferably has a diameter in the range of about 0.5 mm to about 1.0 mm, and most preferably about 0.8 mm. The strand  30  may be coated with a low-friction material such as known plastic or hydrophilic coatings. 
         [0021]    This construction of the tissue anchor  24  and its loop  32  allows the suture  22  to be tensioned and slid through the loop  32  relative to the crossbar  24  while preventing the suture  22  from engaging the crossbar  24  or the edges defined by the elongated aperture  38 . That is, no matter which direction the ends of the suture  22  are pulled or slid relative to the crossbar  24 , the wire  30  and its loop  32  will serve as a barrier between the suture  22  and the canula  24  to prevent any undesired abrasion therebetween. Generally, the strand  30  has a length and the location of the apex A of the loop  32  are such that the loop  32  is sized to project through the tissue in which it is embedded (e.g. it projects from the proximal side of the tissue), allowing reliable tensioning of the suture  22  and preventing abrasion of the tissue. 
         [0022]    Turning now to  FIG. 3 , another embodiment of a tissue anchor  120  is depicted in accordance with the teachings of the present invention. As in the prior embodiment, the anchor  120  generally includes a crossbar  124  having opposing ends  126  and  128 . A strand  130  is connected to the crossbar  124 , and in this embodiment, the strand  130  is formed of a flexible suture. The crossbar  24  defines first and second apertures  138 ,  140  which are longitudinally spaced apart. Moving from left to right in  FIG. 3 , the strand  130  is attached to the crossbar  124  and passes through the interior of the crossbar  124  and exits radially from the first aperture  138 , then extends along the outer periphery of the crossbar  124 , and passes back through the second aperture  140  into the interior of the crossbar  124 , where it is fixed to the second end  128  thereof. Accordingly, the flexible suture  130  and the crossbar  124  define a loop  132  therebetween which is sized to slidably receive the tying suture  22 . The suture  130  has a length, preferably about 10 mm to about 30 mm, such that the distance the suture  130  projects away from the crossbar  124  is variable. The suture  130 , when pulled taut, defines an apex that is positioned away from an outer surface of the crossbar about 5 mm. Preferably the suture  130  has a length 18 mm, whereas the crossbar  124  has a length of about 8 mm. The suture  130  may be of a single filament or multi-filament constructions. Through this construction of the suture  130  to form the loop  132 , while friction between the anchor  120  and the tying suture  22  is reduced. The loop  132  and with the extra length of the suture  130 , the crossbar  124  may be embedded deeper into the tissue. 
         [0023]    Turning now to  FIGS. 4 and 5 , in yet another embodiment of a tissue anchor  220  has been depicted in accordance with the teachings of the present invention. As with the prior embodiments the anchor  220  generally includes a crossbar  224  having opposing ends  226  and  228 . In this embodiment the crossbar  224  is preferably formed of a solid cylinder, and may be a metal bar, plastic molded piece, or any stock materials. The tissue anchor  220  also includes a flange  240  connected to the crossbar  224  and projecting radially away therefrom. The flange  240  preferably has a thickness (best seen in the side view of  FIG. 5 ) that is less than 50% of the diameter of the crossbar  224 . The flange  240  defines a hole  242  sized to slidably receive the tying suture  22  therein. Preferably, the crossbar  224  and flange  240  are unitarily and integrally formed, such as in a plastic molding process. Accordingly, the entire tissue anchor  220  may be formed of a single plastic material, and most preferably a resorbable material. This construction of the tissue anchor  220  allows it to be placed in locations where, once the anchor was freed, it would likely not naturally pass through the body. Accordingly, no matter the location the tissue anchors  220 , they are still allowed to naturally exit the body. 
         [0024]    As used herein, the term “resorbable” refers to the ability of a material to be absorbed into a tissue and/or body fluid upon contact with the tissue and/or body fluid. A number of resorbable materials are known in the art, and any suitable resorbable material can be used. Examples of suitable types of resorbable materials include resorbable homopolymers, copolymers, or blends of resorbable polymers. Specific examples of suitable resorbable materials include poly-alpha hydroxy acids such as polylactic acid, polylactide, polyglycolic acid (PGA), or polyglycolide; tri-methlyene carbonate; polycaprolactone; poly-beta hydroxy acids such as polyhydroxybutyrate or polyhydroxyvalerate; or other polymers such as polyphosphazines, polyorgano-phosphazines, polyanhydrides, polyesteramides, poly-orthoesters, polyethylene oxide, polyester-ethers (e.g., poly-dioxanone) or polyamino acids (e.g., poly-L-glutamic acid or poly-L-lysine). There are also a number of naturally derived resorbable polymers that may be suitable, including modified polysaccharides, such as cellulose, chitin, and dextran, and modified proteins, such as fibrin and casein. 
         [0025]    Turning now to  FIGS. 6-9 , the tissue anchors  20  are preferably deployed as a set of anchors  20   a ,  20   b ,  20   c ,  20   d  linked together by a single suture  22 , all of which collectively forms a medical device  50  for closing the perforation  10  in the bodily wall  12 . The suture  22  is slidably connected to each of the tissue anchors  20   a ,  20   b ,  20   c , and  20   d , leaving two free ends  52 ,  54  of the suture  22  which may be independently tensioned to close the perforation  10 . As best seen in  FIG. 7 , the tissue anchors ( 20   b  and  20   c  depicted) are positioned on a distal side of the bodily wall  12 , while the majority of suture  22  is positioned on a proximal side of the bodily wall  12 , including the suture ends  52 ,  54 . Accordingly, it will be recognized that the medical device  50  operates in a purse-string fashion to close the perforation  10  in the bodily wall, as will be described in more detail below. 
         [0026]    A method of closing the perforation  10 , in accordance with the teachings present invention, includes passing each tissue anchor  20   a ,  20   b ,  20   c , and  20   d  through the bodily wall  12  adjacent the periphery of the perforation  10 , as shown in  FIG. 6 . Preferably, the anchors are sequentially positioned around the perforation  10  in a semi-annular or annular shape as shown. The ends  52 ,  54  of the suture are then tensioned to reduce the distance between the tissue anchors  20   a ,  20   b ,  20   c ,  20   d  and compress the bodily wall  12  around the perforation  10 , as depicted in  FIGS. 8 and 9 . As best seen in  FIG. 9 , the ends  52 ,  54  of the suture  22  are secured to maintain the compression of the bodily wall  10 , such as through the use of a suture lock  56 . Exemplary suture locks are disclosed in copending U.S. patent application Ser. Nos. 12/125,525 and 12/191,001, the disclosures of which are incorporated herein by reference in their entirety. It will be recognized that any now known or future developed method for securing the ends  52 ,  54  of the suture  22  may be employed, such as knotting, tying, clamps, rivets and the like. 
         [0027]    The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.