Patent Publication Number: US-2006004409-A1

Title: Devices for locking and/or cutting a suture

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
      This application claims priority to and incorporates by reference U.S. Provisional Patent Application No. 60/571,000 filed May 14, 2004 entitled “Suture locking and cutting mechanisms that are suitably small enough to pass through the working channel of an endoscope”. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to endoscopic suturing devices. More particularly, this invention relates to suture locking and cutting mechanisms that are small enough to pass through the working channel of various endoscopic and ultrasound devices.  
     BACKGROUND  
      Application of sutures in the gastrointestinal tract is required for several different types of medical procedures, for example, for transoral endoscopic valvuloplasty for gastroesophageal reflux disease (GERD), gastroplasty, fundoplication, anterior gastropexy, posterior gastropexy, suturing esophageal perforations, or closure of the esophageal side of the tracheo-esophageal fistula. Traditionally, these procedures are performed by physicians, such as gastroenterologists or surgeons, either by laparoscopy or open surgical techniques. Such procedures are invasive, as laparoscopy requires that small access incision(s) be made in the body of the patient, through which a laparoscope and other surgical enabling tools are provided, while open surgical techniques are traditionally invasive and can have complications and cause long patient recovery periods.  
      The solution to these problems is to perform these medical procedures through the gastroesophageal tract via the mouth or other naturally occurring orifice. Already available flexible endoscopes, commonly called gastroscopes, can be provided through the gastroesophageal tract and enable illumination and visualization of tissue along the gastroesophageal tract on a video display for diagnostic purposes. These flexible endoscopes also provide an instrumentation means for applying sutures in tissue, such as in the wall of the stomach. What is needed are improved methods of providing a totally transoral surgical procedure, such as a posterior gastropexy procedure, and thereby avoid more invasive laparoscopic procedures.  
      New endoscopic suturing methods performed through the gastroesophageal tract as an alternative to the invasive laparoscopic method of, for example, a posterior gastropexy procedure, are currently being developed. For example, suturing methods under the control of endoscopic ultrasound (EUS) are being evaluated. EUS is a procedure that combines endoscopy and ultrasound. In particular, a Mar. 14, 2003 publication authored by Fritscher-Ravens, Mosse, Mukherjee, Yazaki, Park, Mills, and Swain, entitled, “Transgastric gastropexy and hiatal hernia repair for GERD under EUS control: a porcine model,” (American Society for Gastrointestinal Endoscopy) describes how endoluminal operations for gastroesophageal reflux are currently limited by the inability of the surgeon to visualize and manipulate structures outside the wall of the gut. The publication describes a way to define the EUS anatomy of structures outside the gut that influence reflux, to place stitches in the median arcuate ligament, to perform posterior gastropexy, and to test the feasibility of crural repair, under EUS control, in pigs. More specifically, by using a linear-array EUS, the median arcuate ligament and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and suture. These were anchored into the muscle. An endoscopic sewing device was used, which allowed stitches to be placed through a 2.8-mm accessory channel to any predetermined depth.  
      The publication also describes new methods of knot tying and suture cutting through the 2.8-mm channel of the EUS. More specifically, stitches were placed through the gastric wall into the median arcuate ligament, and one stitch was placed just beyond the wall of the lower esophageal sphincter. The stitches were tied together and locked against the gastric wall, and the surplus length of suture material was then cut and removed. While this publication describes a suitable transgastric gastropexy and hiatal hernia repair procedure, further improvements in methodology and equipment to perform such procedures would be beneficial. For example, the publication describes a process for locking and cutting the suture from inside the stomach. However, the suture requires that a separate suture cutting step, along with its associated cutting instrumentation, be available via the working channel of the endoscope. This may result in multiple passes of instrumentation back and forth through the working channel of the endoscope. What is needed is a way to both lock and cut a suture automatically with a single device and thereby simplify the medical procedure, such as a posterior gastropexy procedure.  
      It is therefore an object of an aspect of the invention to provide improved methods of performing a totally transoral surgical procedure, such as a posterior gastropexy procedure, and thereby avoid more-invasive laparoscopic procedures.  
      Additionally, the locking mechanism described in the publication is too large to pass through the working channel of an endoscope and, thus, it must be inserted into the patient separately from the endoscope, which again adds complexity to the medical procedure. What is needed are suture locking and cutting mechanisms that are small enough to pass through the working channel of various endoscopic and ultrasound devices (typical working channel diameter is 2.8-3.4 mm).  
      Various forms of suture-locking device are described in U.S. Pat. No. 4,235,238 (Ogiu et al). In particular, this US patent describes various forms of suture-locking device which employ some form of suture-finishing stop, which, it is asserted, can be used to clamp the suture. However, all the designs described appear to be inherently unreliable (they are likely either not to clamp the suture in the first place, or, if they have done so, to work loose subsequently), or they lack flexibility in terms of how they can used (the lock can be made progressively tighter by the endoscopist, but the process can never be reversed if the endoscopist has made it too tight). There is thus a need for a suture-locking device which can overcome these problems.  
      A suture cutting device is described in GB-A-2247841. This employs a cutting tube which is slideable over an elongated rod, the rod having a pair of eyelets through which the suture material to be cut passes. However, the device is not described as being useable via a flexible endoscope, and appears in fact only to be useable during rigid endoscopy.  
      Another suture cutting device is described in Japanese Utility Model Application No. 158729/1978. However, this attempts to hold the suture during cutting by means of a pair of open-ended slots in an outer member, and a corresponding slot in an inner member. This is unlikely to hold the suture securely under many circumstances, thereby rendering it unsatisfactory for surgical use.  
      WO95/25470 describes a suture cutting device which is for use in conjunction with a flexible endoscope. However, this achieves its cutting action by having the suture passing through slots in an inner member, and then around the outside of the endoscope. Also, the technique requires the suture to be held under tension during the cutting operation. This combination of features means that the cutting operation may not be as reliable as is desired.  
      It is an object of other aspects of this invention to provide a single mechanism for automatically locking and/or cutting a suture and thereby simplifying medical procedures, such as, but not limited to, a posterior gastropexy procedure.  
      It is yet another object of this invention to provide suture locking and cutting mechanisms that are small enough to pass through the working channel of various endoscopic and ultrasound devices.  
     SUMMARY OF THE INVENTION  
      Certain embodiments of the present invention are directed to providing improved methods of performing a totally transoral surgical procedure, such as a posterior gastropexy procedure, and thereby avoiding more-invasive laparoscopic procedures. One embodiment of the present invention provides a device and method that allows a physician in a medical procedure to automatically lock and cut a suture in one motion and without the need for additional cutting instrumentation, rather than perform separate locking and cutting actions.  
      In one embodiment of the invention, a suture lock assembly in combination with a lock actuating device is provided. The lock comprises an extension spring arranged between two endcaps, wherein one or more sutures are locked within the coils thereof. Extending the extension spring allows for one or more sutures to be threaded therethrough and, by relaxing the extension spring, provides a clamping action upon the sutures and a tortuous path within the coils. The lock actuating device provides a cutting mechanism. Furthermore, both the suture lock assembly, in combination with a lock actuating device, are suitably small enough to pass through the working channel of various endoscopic and ultrasound devices.  
      In another embodiment of the invention, a suture lock assembly is provided that forms a hollow body, within which a clamp device is engaged and through which one or more sutures is threaded. Depending upon the slidable position of the clamp device within the body, the suture within the clamp device is engaged to clamp the suture permanently. The suture lock assembly of this embodiment is likewise suitably small enough to pass through the working channel of various endoscopic and ultrasound devices.  
      In yet another embodiment of the invention there is provided a suture-locking device which comprises an outer tubular member, and an inner tubular member which has a distal portion of a first cross-section and a proximal portion of a second cross-section, the said first portion having an aperture formed therethrough and sized to allow a suture to pass therethrough, the device having a non-locking state in which the said second portion is at least partly received in the outer tubular member, and the said aperture is so located that the suture can pass freely through it, and a locking state in which the said first portion is located at least partially within the outer tubular member, and the suture is locked between the inner and outer tubular members. Preferably, the first and second portions of the inner tubular member are connected to one another by an intermediate portion. More preferably, the first and second portions are at least substantially cylindrical, and the intermediate portion is a tapered portion which integrally connects the first and second portions.  
      In another aspect of the invention, which may be combined with the immediately preceding embodiment, a suture-locking device is provided which comprises a pair of locking members movable with respect to one another from a non-locking position to a locking position, and pulling means for effecting movement of one of the tubular members relative to the other, the pulling means being connected to the said one member by a connection which is sufficiently strong to enable a force to be applied thereto to effect that relative movement, but which is breakable under a higher force to allow the pulling means to be detached from the tubular members after locking.  
      In a further embodiment of the invention there is provided a device for cutting a surgical suture, the device comprising a tubular member having a longitudinal axis and a tubular wall with a pair of apertures extending therethrough, the apertures being sized and arranged to permit a surgical suture to pass into the tubular member through one of the pair of apertures and out of the tubular member through the other, a cutting member received within the tubular member, and means for causing longitudinal movement of the cutting member and tubular member with respect to one another in a direction to cause the cutting member to pass at least one of the pair of apertures to sever the suture passing therethrough. Preferably the pair of apertures are preferably longitudinally spaced from one another. They are also preferably offset with respect to one another about the longitudinal axis of the tubular member, and more preferably they are offset from one another by 180 degrees, or approximately 180 degrees.  
      In still another embodiment of the invention there is provided a device for locking and cutting a suture, which comprises a first member having an aperture sized to allow a suture to pass through, the first member having a distal end and a proximal end, a second member with respect to which the first member is movably mounted, and means releasably connected to the first member for pulling it in a proximal direction from a first position in which the suture is free to pass through the said aperture, via a second position in which the suture is clamped between the first and second members, to a third position in which the suture is cut by cooperation between the first and second members.  
      In a preferred aspect of the immediately preceding embodiment, the second member is generally cylindrical, and the first member is slidable within the first member. In the first position only the proximal end portion of the first member is received within the second member. In the second position the first member is received within the second member to a greater extent. In the third position the first member is at least substantially received within the first position. The releasable connection between the pulling means and the first member is arranged to separate when a force is applied to the pulling member sufficiently in excess of that required to move the first member into the third position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      While the novel features of the invention are set forth with particularity in the appended claims, the invention, in all its embodiments, may be more fully understood with reference to the following description and accompanying drawings.  
       FIG. 1A  illustrates a perspective view of a suture lock assembly in accordance with a first embodiment of the invention;  
       FIG. 1B  illustrates a cross-sectional view of the suture lock assembly in accordance with a first embodiment of the invention;  
       FIG. 2  illustrates a side view of an exemplary lock actuating device;  
       FIGS. 3A and 3B  illustrate a side view and a top view, respectively, of the distal end of the lock actuating device with the suture lock assembly of the first embodiment engaged therein in the default state;  
       FIGS. 4A and 4B  illustrate a side view and a top view, respectively, of the distal end of the lock actuating device with the suture lock assembly of the first embodiment engaged therein in the lock state;  
       FIGS. 5A and 5B  illustrate a side view and a top view, respectively, of the distal end of the lock actuating device with the suture lock assembly of the first embodiment engaged therein in the cut state;  
       FIG. 6  illustrates a side view of the suture lock assembly of the first embodiment engaged therein in the release state;  
       FIG. 7  illustrates a flow diagram of an example method of using the suture lock assembly of the first embodiment in combination with the lock actuating system;  
       FIG. 8  illustrates a perspective view of a suture lock assembly in accordance with a second embodiment of the invention.  
       FIG. 9  illustrates a cross-sectional view of the suture lock assembly of the second embodiment in the unlocked state.  
       FIG. 10  illustrates a cross-sectional view of the suture lock assembly of the second embodiment in the locked state.  
       FIGS. 11A and 11B  illustrate cross section views of an alternative locking device with a one-way flap inside a tubular segment, in a loading state, and a locked state, respectively.  
       FIGS. 12A and 12B  show a cross section view of alternative one-piece clip in a default state, and a cross section view of the one-piece clip in a locked state, respectively.  
       FIG. 13  shows the head of an embodiment of locking device, on a much enlarged scale, with a suture therein ready to be locked;  
       FIG. 14  is a disassembled view of the head of  FIG. 13 , showing the individual components;  
       FIG. 15  shows the head of  FIGS. 13 and 14  and Bowden cable and handle with which it is associated to form a complete locking device;  
       FIGS. 16   a  to  16   g  show successive steps in the operation of the locking device of FIGS.  13  to  15 ;  
       FIG. 17  is a longitudinal section, on a much enlarged scale, of an embodiment of cutter head;  
       FIG. 17   a  is a similar section of a modified version of the device of  FIG. 17 ;  
       FIG. 18  shows the complete cutting device, including the cutter head of  FIGS. 17 and 17   a;    
       FIG. 19  shows the flexible endoscope with which the device of FIGS.  17  to  18  is to be used;  
       FIGS. 20   a  through  20   f  show successive stages in a cutting procedure using the cutter of  FIGS. 17 through 19 ;  
       FIG. 21  shows the components of a combined locking and cutting device in disassembled form;  
       FIG. 22  shows the components of  FIG. 21  in assembled form;  
       FIG. 23  shows the device of  FIGS. 21 and 22  in the process of being introduced through the working channel of a flexible endoscope;  
       FIGS. 24   a  and  24   b  show the device of  FIGS. 21 and 22  positioned adjacent an area of tissue, with  FIG. 24   b  being on a larger scale than  FIG. 24   a;  and  
       FIGS. 25   a  through  25   d  show successive stages in the operation of the device of  FIGS. 21 and 22 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1A  illustrates a perspective view of a suture lock assembly  100  in accordance with a first embodiment of the invention. Suture lock assembly  100  includes an extension spring  112  arranged between a distal endcap  114  and a proximal endcap  116 . The endcaps preferably have an outer diameter of about 0.07 inch. Extension spring  112  is formed of any nontoxic, noncorrosive metal, such as stainless steel, and distal endcap  114  and proximal endcap  116  are formed of, for example, molded plastic or stainless steel. Also shown in  FIG. 1  is a suture  118  threaded first through a hole  120  in distal endcap  114  and then through multiple coils of extension spring  112 , wherein suture  118  is clamped because of the pressure of the coils and the tortuous path within the coils. Suture lock assembly  100  is not limited to a single suture  118  installed therein; a plurality of sutures  118  may be engaged within a single suture lock assembly  100 .  
       FIG. 1B  illustrates a cross-sectional view of suture lock assembly  100  taken along line AA of  FIG. 1A . This view shows that proximal endcap  116  further includes a hollow channel  121  that runs through its center. Furthermore, hole  120  in distal endcap  114  is angled from the center of an outer end of distal endcap  114  toward the sidewall of distal endcap  114 , preferably at an angle of about 45° to the central axis which thereby allows suture  118  to exit distal endcap  114  external to extension spring  112 . Distal endcap  114  and proximal endcap  116  may be insert-molded onto extension spring  112  or use other methods or procedures of providing a smooth, trauma free extension of spring coils.  
      In operation, suture  118  is threaded first through hole  120  in distal endcap  114 ; extension spring  112  is then extended and suture  118  is threaded through multiple coils of extension spring  112 ; extension spring  112  is then relaxed, which thereby applies a tortuous path in addition to a clamping or locking action upon suture  118  between the coils thereof. The overall diameter of suture lock assembly  100  is suitably small enough to allow it to pass through the working channel of various endoscopic and ultrasound devices, which is typically between 2.8 and 3.4 mm in diameter. See Table 1 for example dimensions of suture lock assembly  100 .  
               TABLE 1                          Example dimensions of suture lock assembly 100                         Example Dimension                                             Suture lock assembly 100 overall length   0.70   in           Extension spring 112 outside diameter   0.060   in           Extension spring 112 inside diameter   0.040   in           Distal endcap 114 outside diameter   0.07   in           Distal endcap 114 length   0.15   in           Proximal endcap 116 outside diameter   0.07   in           Proximal endcap 116 length   0.125   in           Hollow channel 121 diameter   0.04   in           Hole 120 diameter   0.04   in           Hole 120 angle   45   degrees                      
 
       FIG. 2  illustrates a side view of a lock actuating device  200 , which is exemplary only and representative of any suitable actuating device for use with suture lock assembly  100 . In this example, lock actuating device  200  includes a body  210  that has a knob  212  arranged at its proximal end for grasping by the user. Mechanically coupled to body  210  is a retract handle  214 , which has a retract handle body  216  and a retention handle  218  that is slidably arranged within retract handle body  216 . Furthermore, a compression spring  220  is mechanically coupled between a spring retainer  222 , which is coupled to knob  212 , and the proximal end of retract handle body  216 . Mechanically coupled to the distal end of retract handle body  216  is a hollow retractable sleeve  224 , within which is first arranged a hollow retention sleeve  225 , which has a retention jaw  226  at its distal end. Furthermore, arranged within retention sleeve  225  is an actuating shaft  228 .  FIG. 2  also shows that arranged within the distal end of retractable sleeve  224  is a first slot  230  that is aligned opposite a second slot  232 . Also, arranged within the distal end of retention sleeve  225  is a hole  234  that is aligned opposite a slot  236 .  
      Actuating shaft  228  of a fixed length is mechanically coupled at one end to the distal end of spring retainer  222  while passing through spring retainer  222 . Actuating shaft  228  passes through a hollow channel within retract handle body  216 , then passes through the hollow channel of retention jaw  226  within retractable sleeve  224 . The tip of actuating shaft  228  extends through an opening at the distal end of retention jaw  226  within retractable sleeve  224 . Using retract handle  214  and retention handle  218 , retractable sleeve  224  and retention sleeve  225  are slidable along the length of actuating shaft  228 . As a result, the relative axial position of retractable sleeve  224 , retention jaw  226 , and actuating shaft  228  may vary one to another under user control. Lock actuating device  200  may include well-known mechanical methods and elements (not shown) for holding retractable sleeve  224  and retention jaw  226  at various positional states.  
      The operation of suture lock assembly  100  in combination with lock actuating device  200  for automatically locking and cutting a suture includes a sequential transition from a default state (i.e., undeployed state) to a lock state, a cut state and, finally, a release state (i.e., deployed state), as described in reference to  FIGS. 3A, 3B ,  4 A,  4 B,  5 A,  5 B,  6 , and  7 . Additionally,  FIGS. 3A, 3B ,  4 A,  4 B,  5 A,  5 B, and  6  show suture lock assembly  100  in use and, therefore, it includes suture  118 , which runs through the center of suture lock assembly  100  and approximates a first tissue  122  and a second tissue  124 . Suture  118  is anchored to second tissue  124  with a T-tag  126 , which is a well-known medical device for anchoring a suture into body tissue.  
       FIGS. 3A and 3B  illustrate a side view and a top view, respectively, of the distal end of lock actuating device  200  with suture lock assembly  100  engaged therein in the default state, which is described as follows.  
      Default State:  
      In the default or undeployed state, extension spring  112  is extended suitably to allow suture  118  to slide freely through its coils. This is accomplished by the physician&#39;s passing actuating shaft  228  through hollow channel  121  of proximal endcap  116 , then through the center of extension spring  112 , until the tip of actuating shaft  228  abuts the inner surface of distal endcap  114 . By using retention handle  218 , which is attached to the proximal end of retention sleeve  225 , the physician extends retention jaw  226  to allow it to grip proximal endcap  116  and then pull proximal endcap  116  into the tip of retractable sleeve  224 , as shown in  FIGS. 3A and 3B , which thereby extends extension spring  112 , relative to the tip of actuating shaft  228 . The distance between the tip of actuating shaft  228  and the tip of retractable sleeve  224  is predetermined to suitably extend extension spring  112 . Additionally, suture  118  is threaded first through hole  120  in distal endcap  114 , then within the extended coils of extension spring  112  is wrapped multiple times around actuating shaft  228 , through hole  234  of retention sleeve  225 , through first slot  230  of retractable sleeve  224 , passes around actuating shaft  228 , through slot  236  of retention sleeve  225  and, finally, through second slot  232  of retractable sleeve  224 .  
       FIGS. 4A and 4B  illustrate a side view and a top view, respectively, of the distal end of lock actuating device  200  with suture lock assembly  100  engaged therein in the lock state, which is described as follows.  
      Lock State:  
      In the lock state, extension spring  112  is relaxed, which allows its coils to clamp against suture  118  and thereby prevent suture  118  from sliding freely between the coils of extension spring  112 . By using retention handle  218 , which is attached to the proximal end of retention sleeve  225 , the physician extends retention jaw  226  while gripping proximal endcap  116  in a direction toward distal endcap  114  and while maintaining the relative distance between the tip of actuating shaft  228  and the tip of retractable sleeve  224 , as set in the default state. Although the relative position of hole  234  and slot  236  to first slot  230  and second slot  232 , respectively, is changed, suture  118  is intact and passing freely through hole  234  of retention sleeve  225 , through first slot  230  of retractable sleeve  224 , passes around actuating shaft  228 , through slot  236  of retention sleeve  225 , and through second slot  232  of retractable sleeve  224 , as shown in  FIGS. 4A and 4B .  
       FIGS. 5A and 5B  illustrate a side view and a top view, respectively, of the distal end of lock actuating device  200  with suture lock assembly  100  engaged therein in the cut state, which is described as follows.  
      Cut State:  
      In the cut state, the relative distance between the tip of actuating shaft  228  and the tip of retention jaw  226  is maintained, as set in the lock state. By using retract handle  214 , which is attached to the proximal end of retractable sleeve  224 , the physician retracts tip of retractable sleeve  224  in a direction away from the tip of retention jaw  226 , which causes the position of hole  234  and slot  236  within retention sleeve  225  to change, relative to first slot  230  and second slot  232 , respectively, such that suture  118  within hole  234  is cut as hole  234  passes underneath the edge of first slot  230 , which has a ground edge suitable for cutting suture  118 .  
       FIG. 6  illustrates a side view of suture lock assembly  100  in the release state, which is described as follows.  
      Release State:  
      In the release state, the physician manipulates the grasp of retention jaw  226  and proximal endcap  116  is released, which allows all instrumentation, such as lock actuating device  200  and the endoscope, as well as the surplus length of suture  118 , to be removed. Extension spring  112  remains relaxed and, thus, the locking action upon suture  118  is maintained indefinitely within the patient.  
       FIG. 7  illustrates a flow diagram of an example method  700  of using suture lock assembly  100  in combination with lock actuating device  200  in accordance with the invention. More specifically, method  700  provides an example of a posterior gastropexy procedure that uses suture lock assembly  100  of the present invention. The use of suture lock assembly  100  is not limited to a posterior gastropexy procedure; suture lock assembly  100  may be used in any of various, similar medical procedures. Furthermore, method  700  is not limited to a single suture  118  installed within suture lock assembly  100 ; a plurality of sutures  118  may be engaged within a single suture lock assembly  100 .  
      At step  710 , a physician passes an EUS endoscope through a patient&#39;s mouth and esophagus and into the stomach. Example EUS endoscopes include endoscope model GF-UC160P-AT8 manufactured by Olympus Europe (Hamburg, Germany) and endoscope model EG-3630U manufactured by Pentax Medical Company (Orangeburg, N.Y.). The working channel of the EUS endoscope is preloaded with a standard EUS needle, such as is manufactured by Wilson-Cook (Winston-Salem, N.C.), that serves as a carrier for a tag and suture, such as T-tag  126  and suture  118 . Suture  118  may run either through the needle or outside the needle, but still inside the working channel of the EUS endoscope.  
      At step  712 , under the guidance of the EUS endoscope, the physician locates and identifies structures outside the stomach wall and selects a fixation point, such as the median arcuate ligament.  
      At step  714 , under the guidance of the EUS endoscope, the physician pushes the EUS needle, which is carrying T-tag  126  and suture  118 , through the stomach wall, which is represented by first tissue  122  in  FIGS. 3A, 3B ,  4 A,  4 B,  5 A,  5 B, and  6 .  
      At step  716 , under the guidance of the EUS endoscope, the physician deploys and affixes T-tag  126 , with suture  118  attached thereto, to the fixation point, such as to the median arcuate ligament, which is represented by second tissue  124  in  FIGS. 3A, 3B ,  4 A,  4 B,  5 A,  5 B, and  6 .  
      At step  718 , the physician withdraws the EUS endoscope and associated instrumentation from the patient, but leaves a length of suture  118  still threaded through the patient&#39;s gastroesophageal tract and anchored to second tissue  124  (e.g., median arcuate ligament). The length of suture  118  extends out of the patient&#39;s mouth and is accessible to the physician.  
      At step  720 , the physician threads the length of suture  118  that is extending out of the patient&#39;s mouth into the distal end and out of the proximal end of the working channel of a standard endoscope that has a standard vision system (i.e., not an EUS endoscope).  
      At step  722 , while holding tension on suture  118 , the physician passes the endoscope through the patient&#39;s mouth and esophagus and into the stomach. A length of suture  118  is left extending out of the proximal end of the working channel of the endoscope and is accessible to the physician.  
      At step  724 , the physician loads suture lock assembly  100  into the distal end of lock actuating device  200  and sets suture lock assembly  100  into the default state, as described in reference to  FIGS. 3A and 3B .  
      At step  726 , with suture lock assembly  100  in the default state and loaded into lock actuating device  200 , the physician first threads the length of suture  118  that is extending out of the proximal end of the endoscope through hole  120  in distal endcap  114 , then within the extended coils of extension spring  112  is wrapped multiple times around actuating shaft  228 , then threaded through hole  234  of retention sleeve  225 , then threaded through first slot  230  of retractable sleeve  224 , then threaded through second slot  236  of retention sleeve  225  and, finally, threaded through second slot  232  of retractable sleeve  224 , as shown in  FIGS. 3A and 3B .  
      At step  728 , while holding tension on suture  118 , which is extending out of second slot  232  of retractable sleeve  224 , the physician passes the suture lock assembly  100  and retractable sleeve  224  of lock actuating device  200  through the working channel of the endoscope and into the patient&#39;s stomach. Suture lock assembly  100  is sliding freely along suture  118  in the default state, until distal endcap  114  is firmly abutted against the inside of the stomach wall, which is represented by first tissue  122  in  FIGS. 3A, 3B ,  4 A,  4 B,  5 A,  5 B, and  6 .  
      At step  730 , having determined that the desired geometry change between the stomach and the median arcuate ligament (represented by first tissue  122  and second tissue  124 ) is achieved and while continuing to hold tension on suture  118 , the physician sets suture lock assembly  100  into the lock state by using retention handle  218 , as described in reference to  FIGS. 4A and 4B , which causes the coils of extension spring  112  to relax and create a torturous path and, thus, clamp against suture  118 , as shown in  FIGS. 4A and 4B .  
      At step  732 , having secured suture lock assembly  100  against first tissue  122  with suture  118 , the physician sets suture lock assembly  100  into the cut state by using retract handle  214 , as described in reference to  FIGS. 5A and 5B , which causes suture  118  to be cut as hole  234  passes underneath the edge of first slot  230 , which has a geometry suitable for cutting suture  118 , as shown in  FIGS. 5A and 5B .  
      At step  734 , having secured suture lock assembly  100  against first tissue  122  and having cut suture  118 , the physician releases retention jaw  226  from proximal endcap  116  of suture lock assembly  100 , which allows all instrumentation, such as lock actuating device  200  and the endoscope, and the surplus length of suture  118 , to be withdrawn from the patient, while suture  118  remains firmly clamped, as shown in  FIG. 6 . Method  700  ends.  
       FIG. 8  illustrates a perspective view of a suture lock assembly  800  in accordance with a second embodiment of the invention. Suture lock assembly  800  includes a cylindrical-shaped lock body  810  that further includes a plurality of suture channels  812  that run therethrough, and which have an associated plurality of locking holes  814  arranged on the outer surface of lock body  810 . Suture lock assembly  800  further includes a lock sleeve  816  that further includes a cavity  818  (shown in  FIGS. 9 and 10 ) within which lock body  810  is inserted. Preferably there is a clearance of 0.001 inch or less between the outer surface of the lock body  810  and the inner surface of the lock sleeve  816 . Lock body  810  further includes a first groove  824  and a second groove  826 , which are detents formed around the outer perimeter of lock body  810 . Lock sleeve  816  further includes a first locking ring  820  and a second locking ring  822 , which are raised regions protruding from the inside perimeter of cavity  818  that are sized to lock within the detents formed by first groove  824  and second groove  826  of lock body  810 .  
      Also shown in  FIG. 8  is suture  118 , which is anchored to second tissue  124  with T-tag  126  passes through first tissue  122  and into one of the suture channels  812 , and exits lock body  810  via one of associated locking holes  814 . Only a small portion of the distal end of lock body  810  is inserted into cavity  818 , such that locking holes  814  are not within cavity  818  of lock sleeve  816 . Lock body  810  and lock sleeve  816  are formed of, for example, molded plastic or stainless steel.  
       FIG. 9  illustrates a cross-sectional view of a suture lock assembly  800  and shows suture  118  passing through one of the suture channels  812  and existing lock body  810 .  FIGS. 8 and 9  are representative of suture lock assembly  800  in the default, unlocked state wherein one or more sutures  118  may be threaded freely through lock body  810 . In the default or unlocked state first locking ring  820  of lock sleeve  816  is engaged within second groove  826  of lock body  810 , as shown in  FIGS. 8 and 9 .  
       FIG. 10  illustrates a cross-sectional view of a suture lock assembly  800  in a locked state wherein or more sutures  118  is threaded through lock body  810  and locked therein. More specifically, in the lock state, lock sleeve  816  is pushed over the entire length of lock body  810 , such that suture  118  is clamped between the outer surface of lock body  810  and the wall of cavity  818  of lock sleeve  816 , after which any surplus suture  118  material is cut, which leaves suture lock assembly  800  secured against first tissue  122 . In order to achieve the locked state enough force is applied to lock sleeve  816  against lock body  810  such that first locking ring  820  of lock sleeve  816  disengages from within second groove  826  of lock body  810 . In doing so, lock sleeve  816  slides upon lock body  810  until first locking ring  820  and second locking ring  822  are engaged within first groove  824  and second groove  826 , respectively, of lock body  810 , as shown in  FIG. 10 . The mechanical features of suture lock assembly  800  for coupling lock sleeve  816  to lock body  810  are exemplary only and are not limited to first locking ring  820 , second locking ring  822 , first groove  824 , and second groove  826 . Any well-known coupling method that allows a default and lock state by sliding lock sleeve  816  upon lock body  810  may be used.  
      The overall diameter of suture lock assembly  800  is suitably small enough to allow it to pass through the working channel of various endoscopic and ultrasound devices, which is typically between 2.8 and 3.4 mm in diameter. See Table 2 for example dimensions of suture lock assembly  800 .  
               TABLE 2                          Example dimensions of suture lock assembly 800                         Example Dimension                                         Lock body 810 length   0.35 in           Lock body 810 outside diameter   0.07 in           Suture channels 812 diameter   0.015 in            Lock sleeve 816 length   0.38 in           Lock sleeve 816 inside diameter   0.07 in           Suture lock assembly 800 overall   0.39 in           length when locked                      
 
      The method of using suture lock assembly  800 , in combination with suture  118 , T-tag  126 , first tissue  122 , and second tissue  124 , is generally the same as described in  FIG. 7 , in reference to suture lock assembly  100 , in that it is fed down the working channel of an endoscope and into, for example, a patient&#39;s stomach, in much the same manner. However, suture lock assembly  800  requires no special actuating device; instead, it may be pushed through the working channel of an endoscope with, for example, the tip of a standard catheter. Additionally, its use differs from suture lock assembly  100 , in that suture lock assembly  800  requires separate instrumentation for cutting the one or more sutures  118  engaged therein.  
       FIGS. 11A and 11B  illustrate an alternative locking device similar in function to those previously mentioned. The locking device of  FIGS. 11A and 11B  are designed to lock onto suture  118 , when used in conjunction with the endoscope. The locking device of  FIGS. 11A and 11B  may be placed on suture  118  attached to T-tag  126 , that has been placed through first tissue  122  and second tissue  124  using the previously-described technique.  
      This embodiment comprises a tubular sleeve  1100 , a flap  1105 , and a detent  1120 . Tubular sleeve  1100  may have an outer diameter of about 2.6 mm and an inner diameter of about 1 mm, and may be injection molded from a suitable polymer, such as polycarbonate, as a single piece or as separate pieces which are then fused together to form a unitary structure. In a resting state, flap  1105  is biased toward contact with detent  1120 . Therefore, to load suture  118  into tubular segment  1100 , an introducer  1130  may be used to create space between flap  1105  and detent  1120  as shown in  FIG. 11A . Introducer  1130  may be placed into tubular segment  1100  by pushing from a distal end  1122  of tubular segment  1100 , so that flap is moved away from detent  1120 . Suture may be placed through a central lumen  1135  of introducer  1130 , so that ultimately suture  118  is positioned within tubular segment  1100 . Introducer  1130  is then removed by pulling it out of tubular segment  1100  from a proximal end  1133 , so that introducer  1130  is not trapped between tubular segment  1100  and second tissue  124 .  
      After introducer  1130  is removed, tubular segment  110  may be pushed along suture  118  toward second tissue  124  with a pusher  1140  especially designed for that purpose, as shown in  FIG. 11B . Tension on suture  118  acts to pull flap  1105  partially away from detent  1120  during advancement. When distal end  1122  of tubular segment  1100  reaches second tissue  124 , pusher  1140  is withdrawn and flap  1105  traps suture  118  against detent  1120  so that tubular segment  1100  is held securely in place.  
       FIGS. 12A and 12B  show another alternative concept for locking onto suture  118 .  FIG. 12A  shows a perspective view of a clip  1200  comprising a first gripping surface  1210 , a second gripping surface  1220 , an opening  1230 , and a clasp  1240 . In a default state, clip  1200  is open as shown in  FIG. 12A , so that suture  118  can pass freely through opening  1230 . Clip  1200  may be placed on suture  118  attached to T-tag  126 , that has been placed through first tissue  122  and second tissue  124  using the previously-described technique. Clip  1200  may be placed onto suture  118  so that clasp  1280  is directed toward second tissue  124  and opening  1230  is directed toward the user. Clip  1200  may be pushed down suture  118  using a long flexible tube, such as an endoscope.  
      To lock clip  1200  onto suture  118 , a horn  1270  including a tapered surface  1272  may be used to apply force at a proximal end of clip  1200 , so that first gripping surface  1210  mates with second gripping surface  1220  to securely hold onto suture  118 , while clasp  1280  holds clip  1200  closed. Clip  1200  may be made from any suitable polymer material, such as nylon. Clip  1200  may be injection molded as a unitary piece with a “living hinge” that biases the part to an open position in which a first gripping surface  1210  is held away from second gripping surface  1220  in a default open state or assembled from multiple pieces.  
      A description will now be given of the locking device shown in  FIGS. 13, 14 ,  15  and  16   a  through  16   g.    FIGS. 13 and 14  show the head  1310  of a locking device comprising, successively along its length, an inner locking tube  1315 , preferably of metal, an outer locking tube  1320 , preferably of a plastics material, and a connecting tube  1325 , preferably of metal, which connects the tube  1320  to the wire-wound sheath  1331  of a Bowden cable  1330 . The inner wire of the Bowden cable is shown as  1332 .  FIG. 13  also shows part of a suture  1350  which the device is to lock.  
      Considering now the individual components in more detail, the tube  1315  can conveniently be formed of the same type of tubing as that used for hypodermic needles, but formed to have a wider distal portion  1316  and a narrower proximal portion, smoothly connected by a tapering portion  1318 . The taper is sufficiently steep to prevent someone handling the device accidentally pushing the tube into the tube  1320 . An aperture  1319  is formed in the wall of the larger diameter portion  1316 . If desired, a pair of such apertures may be provided, for example offset from one another about the axis of the tube by 180°. This makes it easier to use the device to lock together a plurality of sutures, or a lock a single suture to itself at a plurality of points, possibilities which are mentioned again below. The suture  1350  is shown in  FIG. 13  passing through the aperture  1319 . The end edges of the tube  1315  are preferably rounded not shown to reduce the risk of the patient or, indeed, the suture  1350  being cut inadvertently.  
      The tube  1320  is formed of a material which is able to deform to the requisite extent during operation of the device, as will be explained below. It is therefore preferably formed of a plastics material. One material which may be used is polyethylene, though other plastics materials such as polyethyl ethyl ketones may be preferable, as they have less tendency to creep over time as a result of the warmth of the patient&#39;s body. The tube  1320  is a simple cylinder, the internal diameter of which is such that the smaller diameter portion  1317  of the tube  1315  can be held therein by an interference fit. For example, the external diameters of the portions  1316  and  1317  may be 1.7 mm and 1.47 mm respectively, and the internal diameter of the tube  1320  may be 1.4 mm.  
      The connecting tube  1325  is preferably formed of metal, for example of stainless steel. It is in the form of a cylinder with an internally projecting boss  1326  provided, preferably integrally, with the remainder of the cylinder, part way along its length. The internal diameter of the distal portion  1327  of the tube  1325  is such that the end portion of the plastic tube  1320  can be received therein. However, it should not be too tight a fit therein, since at the end of the locking procedure see below the tubes  1320  and  1325  have to be separated from one another. The internal diameter of the proximal portion  1328  of the tube  1325 , which may or may not be the same as the internal diameter of the distal portion  1327 , is such that the wire-wound sleeve  1331  of the Bowden cable  1330  is an interference fit therein. It should be understood, however, that the sleeve  1331  could be additionally or alternatively connected by some other means to the connecting tube  1325 , for example by an adhesive such as a cyanoacrylate adhesive. As will be apparent from what is said below, the connecting tube  1325  is intended to remain permanently fixed to the cable  1330 , without there being need for any movement therebetween, so the connection between them can, and should, be made by as secure a means as possible. It should also be mentioned that in  FIGS. 16   a  to  16   g,  showing the steps in the operation of the device, the connecting tube  1325  has been shown with the portion  1328  omitted and the end of the cable  1330  butt-joined to the boss  1326 . This has been done purely for ease of illustration in  FIGS. 16   e  to  16   g,  and it is to be understood that, in practice, the connecting tube  1325  and cable  1331  would normally be connected as shown in  FIG. 13 , or at least by some other means more secure than a butt joint.  
      As mentioned above, the Bowden cable  1330  has a wire-wound sheath  1331  and an inner wire  1332 . The wire  1332  has a tapered distal end portion  1332   a  which is releasably connected to the tube  1315 . In the illustrated embodiment the wire portion  1332   a  is connected to the smaller diameter portion  1317  of the tube  1315  by solder  1333 , represented purely diagrammatically by the illustrated hexagons. In this way a frangible connection is formed between the wire portion  1332   a  and the tube  1315 . Alternatively, however, some other form of releasable connection could be used. For example, the wire  1332  and tube  1315  could carry respective components of a ball and detent system which, in a similar way to the solder, will provide a connection between the wire and the tube which holds until a certain level of tension is applied, but which permits separation between them once that level of tension is exceeded.  
       FIG. 15  shows, on a much smaller scale than  FIGS. 13 and 14 , the head  1310  of the locking device mounted on one end of the Bowden cable  1330 , and a handle  1340  connected to the other end of the Bowden cable. The handle  1340  comprises an outer member  1341  to which the sheath  1331  of the Bowden cable is attached, and an inner member  1342  which is slideable within the outer member  1341 , and to which the wire  1332  of the Bowden cable is attached. The inner member  1342  can be moved with respect to the outer member  1341  by means of a portion  1343  which can be grasped by a user. It will be understood the handle  1340  is shown only diagrammatically, and that the person skilled in the art could readily substitute for what is shown a handle of a more ergonomic design.  
      The operation of the locking device described above will now be described with reference to  FIGS. 16   a  to  16   g,  which show successive steps in the operation.  
      The starting point for the locking procedure, as shown in  FIG. 16   a,  is that one end of the piece of elongate suture material  1350  has become anchored in an area of tissue  1351  within the body of a patient, either human or animal, for example by a sewing operation. The manner in which this sewing is effected does not form part of the present invention, and there are various known methods by which such sewing can be effected.  
      However, although it is not essential, it is preferred (and the device of the present invention is designed so that this is possible) that in the subsequent locking operation the suture  1350  should pass from the tissue, up through the biopsy channel of the endoscope, and thence to the exterior of the patient. This will automatically be the case if the suture was already present in the biopsy channel during the sewing procedure. If this was not the case then the endoscope tube can to be threaded onto the suture  1350  and passed down into the patient, so that its distal end is adjacent the tissue  1351 , before the locking operation begins. In either event, with the suture  1350  passing through the biopsy channel, the end of the suture that is outside the patient is threaded through the locking device, passing into the interior of the tube  1315  at its distal end, and out of that tube through the aperture  1319 , or one of the apertures  1319 , as the case may be.  
      The arrangement is now as shown in  FIG. 16   a.  It should be noted that  FIG. 16   a  shows a conventional flexible endoscope  1360 , which comprises a head  1361  having a viewing opening  1362  through which an image produced by the endoscope can be viewed by the user, and an elongate flexible tube  1363  which includes the biopsy channel  1364 . Typically this channel has a diameter of between 2.8 mm and 3.4 mm, and constitutes the working channel of the endoscope. As will be apparent from what is said below, the Bowden cable and locking device must be of small enough diameter to pass into and through the biopsy channel.  
      With the arrangement as in  FIG. 16   a,  the proximal end of the suture  1350  is then pulled, so as to take up the slack, and the locking device is slid down over it in a direction towards the biopsy channel. With a tension still being exerted on the suture, the locking device is slid further along it, so that it enters the channel  1364  of the endoscope  1360 , whereafter pushing on the outer member of the handle attached to the sleeve of the Bowden cable causes the locking device and cable both to travel down the biopsy channel. The position is then as shown in  FIG. 16   b.    
      The locking device is then pushed further along the channel  1364 , emerging at the distal end thereof, so that it is located adjacent the area of tissue  1351 , as shown in  FIG. 16   c.    
      Once the locking device has emerged from the distal end of the biopsy channel, and is adjacent the tissue  1351 , locking is caused to take place. This is done by the user pulling on the handle member  1343  so as to draw the tube  1315  rearwards with respect to the other elements of the locking device. This moves the tube  1315  from the position shown in  FIG. 16   d  to the position shown in  FIG. 16   e.  In this movement, the tube  1315  is forced into the tube  1320 , deforming the latter as it does so and trapping the suture between the other wall of the portion  1316  of the tube  1315  and the adjacent portion of the inner wall of the tube  1320 .  
      The locking device is so designed that the transition to the state shown in  FIG. 16   e  can be achieved by applying a relatively low tension to the wire  1332  of the Bowden cable. The tension required is low enough that the connection between the wire portion  1332   a  and the tube  1315  remains intact. The next step is to apply a higher tension which, as shown in  FIG. 16   f,  causes the wire portion  1332   a  to break away from its connection to the tube  1315 . In the illustrated embodiment this involves the breaking of the connection provided by the solder  1333 .  
      Once this connection has been broken, tension is applied to the sheath of the Bowden cable to cause the portion  1327  of the locking cylinder  1325  to slide off the tube  1320 , as shown in  FIG. 16   g.  Continued pulling on the Bowden cable removes it completely from the patient&#39;s body. Once this has been done, all that remains inside the body is what is shown at the left hand side of  FIG. 16   g,  namely the combination of tubes  1315  and  1320 , one inside the other, with the suture  1350  locked between them. It is to be noted that the circumferential wall of the tube  1315  is entirely surrounded by the plastics tube  1320 . This makes it possible, by choosing a suitable material for the tube  1320 , to minimise trauma to the neighbouring tissues.  
      Various modifications can be made to the illustrated embodiment, in addition to those already mentioned above. For example, rather than use a handle of the general form indicated by reference numeral  1340 , the proximal end of the Bowden cable could be attached to a winding device, by means of which tension can be exerted on the wire  1332  thereof by winding it onto a spool. This makes it possible to retract the wire to an unlimited extent, which is not possible using a handle with inner and outer members telescopically arranged. Also, although the device is shown being used to lock a single suture, it could, without modification, be used to lock a plurality of sutures together, or to lock a single suture to itself at a plurality of points.  
      A description will now be given of the cutting device shown in  FIGS. 17, 17   a,    18 ,  19  and  20   a  through  20   f.  As can be seen from a consideration of  FIGS. 17 and 18 , the cutting device comprises a cutter head  1710  mounted on one end of a wire-bound cable (a Bowden cable)  1720 . The other end of the cable  1720  is connected to a handle  1730 .  
      The cutter head  1710  comprises a cylinder  1711  having a portion  1712  at its proximal end which is of larger internal diameter and to which the sheath  1721  of the Bowden cable  1720  is fixedly attached. At its distal end the cylinder  1711  is closed by a nosepiece  1713  having a rounded outer surface to make it easier to introduce the cutter head into and through the biopsy channel of an endoscope (as described further below). The nosepiece  1713  is shown as being an entity distinct from the cylinder  1711 , and it is shown as having a hemispherical outer surface. However, the surface could have some other suitable shape, and it could be provided by an integral portion of the cylinder  1711  itself. Two apertures  1714  are formed through the wall of the cylinder, the apertures being spaced longitudinally from one another and offset from one another around the circumference of the cylinder. In the illustrated embodiment they are offset from one another by 180 degrees, as will be apparent from the ensuing description of the operation of the device. However, some other angle of circumferential offset could be used instead.  
      A cylindrical cutting member  1715  is slideably received within the cylinder  1711 . The inner wire  1722  of the Bowden cable  1720  has its distal end attached to the cutting member  1715 . One way of effecting this attachment is, as shown in the illustrated embodiment, to provide the cutting member  1715  with a longitudinal bore  1716 , the wire  1720  being threaded through the bore and being provided with an enlarged portion  1717  at the distal end, of a size too great to allow it to be withdrawn through the bore. The proximal end of the cutting member  1715  has a cutting edge  1718  formed thereon, for example by forming a hemispherical recess  1719  within the proximal end portion of the cutting member  1715 . Preferably, the wire  1722  is stiff enough to allow the cutting member to be pushed back and thereby reset, so that it can be used repeatedly.  FIG. 17   a  shows a modified form of the attachment between the distal end of the wire  1722  and the cutting member  1715 , which is more suitable when the wire is relatively stiff. This employs a block  1717   a  which is attached, for example by welding, gluing or as a force fit, within the bore  1716 , the distal end of the wire  1722  being itself attached to the block  1717   a  by, for example, crimping.  
      As show in  FIG. 18 , the handle  1730  comprises an outer member  1731  to which the sheath  1721  of the Bowden cable is attached, and an inner member  1732  which is slideable within the outer member  1731 , and to which the wire  1722  of the Bowden cable is attached. The inner member  1732  can be moved with respect to the outer member  1731  by means of a portion  1733  which can be grasped by a user. It will be understood that the handle  1730  is shown only diagrammatically, and that the person skilled in the art could readily substitute for what is shown a handle of a more ergonomic design.  
       FIG. 19  shows diagrammatically a flexible endoscope  1740  with which the cutting device of the present invention may be used. This comprises, as is conventional, a head  1741  having a viewing opening  1742  through which an image produced by the endoscope can be viewed by the user, and an elongate flexible tube  1743  which includes a biopsy channel  1744 , otherwise more generally referred to as the working channel. Typically, this channel has a diameter of around 2.8 mm to 3.4 mm, and the Bowden cable  1720  and cutting device  1710  are of small enough diameter to pass into and through the biopsy channel, in the procedure for use which will now be explained.  
       FIGS. 20   a  through  20   f  show successive steps in carrying out a cutting procedure using the device of the present invention. The starting point, as shown in  FIG. 20   a,  is that one end of a piece of elongate suture material  1750  has become anchored in tissue  1751  within the body of a patient, either human or animal, for example by a sewing operation. The manner in which this sewing is effected does not form part of the present invention, and there are various known methods by which such sewing can be effected. However, it is a preferred (and the device of the present invention is designed so that this is possible) that in the subsequent cutting operation that the suture  1750  should pass from the tissue, up through the biopsy channel of the endoscope, and thence to the exterior of the patient. This will automatically be the case if the suture was already present in the biopsy channel during the sewing procedure. If this was not the case then the endoscope tube can be threaded onto the suture  1750  and passed down into the patient, so that its distal end is adjacent the tissue  1751  before the cutting operation begins. In either event, with the suture  1750  passing through the biopsy channel  1744 , the end of the suture that is outside the patient is threaded through the cutting head  1710 , passing into the interior of the cylinder  1711  through the more distal of the two apertures  1714 , and out of the cutting head through the other of the apertures  1714 . This can be done purely with the user&#39;s figures or with the aid of a conventional needle-threading device. The arrangement is now as shown in  FIG. 20   a.    
      The proximal end of the suture is then pulled, so as to take up the slack, and the cutting head is slid down over it in a direction towards the biopsy channel of the endoscope. The position is then as shown in  FIG. 20   b.    
      With a tension still being exerted on the suture, the cutting head is slid further along it, so that it enters the channel of the endoscope, whereafter pushing on the outer member of the handle attached to the sleeve of the Bowden cable causes the cutting head and cable both to travel down the biopsy channel. The position is then as shown in  FIG. 20   c.    
      Once the cutting head has emerged from the distal end of the biopsy channel, and is adjacent the tissue  1751 , cutting is caused to take place. This is done by the user pulling on the handle member  1733  so as to draw the cutting element  1715  rearwards with respect to the cylinder  1711 . The cutting surface  1718  of the cutting element  1715  thus slides across each of the apertures  1714  in turn, cutting the suture at the points where the suture passes respectively through those apertures. This leaves an off-cut  1750   a  within the cylinder  1711 , a suture portion  1750   b  anchored to the tissue, and a relatively lengthy suture remnant  1750   c  running through the biopsy channel. Alternatively, the cutting element could be arranged to stop before it performs the second, more proximal, cut, in which case no off-cut  1750   a  would be produced. The suture need not be held under tension as the cutter element  1715  is passing the apertures  1714 , provided the cutting element is in sufficiently close engagement with the adjacent cylinder wall to prevent the suture jamming therebetween instead of being cut. The position is now as shown in  FIGS. 20   e  and  20   f.    
      Finally, the cutting device and the remnant of suture  1750   c  are withdrawn from the biopsy channel of the endoscope.  
      A description will now be given of the combined locking and cutting device shown in  FIGS. 21, 22 ,  23 ,  24   a,    24   b  and  25   a  through  25   d.  The device shown in  FIGS. 21 and 22  comprises a piston  2110 , preferably made of steel, a plastics inner tube  2120 , an outer tube  2130 , also made of steel, and a Bowden cable  2140 . Each of these components, and their relationship to one another, will now be described.  
      The piston  2110  is generally cylindrical in shape. At its distal end it has an outwardly directed flange  2111  formed integrally therewith and tapering towards its distal end. The proximal end of the flange  2111  defines a cutting edge  2112 . An aperture  2113  extends through the wall of the piston, the aperture being sized so that a suture which is to be locked and cut by the device can pass freely through it. The suture is shown in  FIG. 22 , and is denoted by reference numeral  2150 . The piston can be regarded as having a distal portion  2114  with a first outer diameter, and a proximal portion  2115  with a second outer diameter which is less than the first diameter. The portions  2114  and  2115  are connected by an inclined portion  2116 , which provides a transition between the first diameter and the second diameter. To provide additional stability, and to assist in the connection of the piston  2110  to the tube  2120  (for which see below), the interior of the piston may be spanned in the region of the junction of the portions  2114  and  2115  by a transverse wall  2117 , the aperture  2113  being located distally of the wall  2117 .  
      The inner tube  2120  has an internal diameter slightly smaller than the external diameter of the portion  2115  of the piston  2110 , such that it can easily be force-fitted over the portion  2115 . However, the outer diameter of the portion  2114  is larger than the internal diameter of the tube  2120  by a sufficient amount to avoid any likelihood of its being accidentally pushed over that portion. The tube  2120  is formed of a material which is able to deform to the requisite extent during operation of the device, as will be explained below. It is therefore preferably formed of a plastics material. One material which may be used is polyethylene, though other plastics materials such as polyethyl ethyl ketones may be preferable, as they have less tendency to creep over time as a result of the warmth of the patient&#39;s body.  
      The outer tube  2130  is preferably of steel, and is bevelled at its distal end  2131 . It is connected to the inner tube by an interference fit. It should be understood, however, that the tube  2130  could be additionally or alternatively connected by some other means to the tube  2120 , for example by an adhesive such as a cyanoacrylate adhesive. As will be apparent from what is said below, the outer tube  2130  is intended to remain permanently fixed to the tube  2120 , without there being need for any movement therebetween, so the connection between them can, and should, be made by as secure a means as possible.  
      The tube  2130  has an inwardly directed flange  2132 , which serves as an abutment for the proximal end of the inner tube  2120 , and for the distal end of the wire-wound sheath  2141  of the Bowden cable  2140 . The internal diameter of the proximal portion of the outer tube  2130 , which may or may not be the same as the internal diameter of the distal portion thereof, is such that the wire-wound sleeve  2141  of the Bowden cable  2140  is an interference fit therein.  
      The Bowden cable  2140  further comprises an inner wire  2142 , which terminates at its distal end in a tapered portion  2143 . The portion  2143  is releasably connected to the piston  2110 . In the illustrated embodiment the wire portion  2143  is connected to the smaller diameter portion  2115  of the tube  2110  by solder  2144 . In this way a frangible connection is formed between the wire portion  2143  and the tube  2110 . Alternatively, however, some other form of releasable connection could be used. For example, the wire  2142  and piston  2110  could carry respective components of a ball and detent system which, in a similar way to the solder, will provide a connection between the wire and the tube which holds until a certain level of tension is applied, but which permits separation between them once that level of tension is exceeded.  
       FIG. 23  shows the device in the process of being introduced through the biopsy channel  2161  (more generally the working channel) of a flexible endoscope  2160 , whose distal end portion is indicated diagrammatically. Referring to  FIGS. 24   a  and  24   b,  it can be seen that the suture  2150  is already anchored, for example by a sewing operation, in an area of tissue  2170  within the body of a patient, either human or animal. The manner in which this sewing is effected does not form part of the present invention, and there are various known methods by which such sewing can be effected. However, it is a preferred (and the device of the present invention is designed so that this is possible) that in the subsequent locking and cutting operation the suture  2150  should pass from the tissue, up through the biopsy channel of the endoscope, and thence to the exterior of the patient. This will automatically be the case if the suture was already present in the biopsy channel during the sewing procedure. If this was not the case then the endoscope tube can to be threaded onto the suture  2150  and passed down into the patient, so that its distal end is adjacent the tissue  2170 , before the locking and cutting operation begins.  
       FIGS. 24   a  and  24   b  show the device after its head, i.e. the combination of components  2110 ,  2120  and  2130 , has passed through the biopsy channel, and is adjacent the area of tissue  2170 . The suture is then locked and cut as described below with reference to  FIGS. 25   a  through  25   d.  It is noted at this point that in each of these figures the plastic inner tube  2120  is hatched to make it easier to identify it, and, therefore, the other components.  
      In the first stage of the process, show by  FIG. 25   a,  tension is exerted on the inner wire  2142  of the Bowden cable, and a corresponding compression on the sheath  2141 , so that the steel piston  2110  slides partially into the tube  2120 . It is able to do this because the plastic tube can deform sufficiently to permit this, even though the initial outer diameter of the distal portion  2114  of the piston  2110  is larger than the inner diameter of the distal portion of the tube  2120 . This traps the suture  2150  between the outer wall of the piston  2110  and the inner wall of the tube  2120 .  
      The relative movement of the piston  2110  and tube  2120  is then continued, as shown in  FIG. 25   b,  so that the cutting edge  2112  of the piston  2110  engages the suture  2150  and severs it.  
      The locking and cutting device is so designed that the transition to the state shown in  FIG. 25   b  can be achieved by applying a relatively low tension to the wire  2142  of the Bowden cable. The tension required is low enough that the connection between the wire portion  2143  and the piston  2110  remains intact. The next step is to apply a higher tension which, as shown in  FIG. 25   c,  causes the wire portion  2143  to break away from its connection to the piston  2110 . In the illustrated embodiment this involves the breaking of the connection provided by the solder  2144 .  
      Finally, as shown in  FIG. 25   d,  once this connection has been broken, the continued application of tension to the sheath of the Bowden cable causes it to slide out of the outer tube  2130 . Continued pulling on the Bowden cable removes it completely from the patient&#39;s body. Once this has been done, all that remains inside the body is what is shown at the left hand side of  FIG. 25   d,  namely the combination of piston  2110  and tubes  2120  and  2130 , one inside the other, with the suture  2150  locked between the piston  2110  and the tube  2120 . It is to be noted that the cutting edge of the flange  2111  is entirely surrounded by the tube  2130 , which avoids any risk of the cutting edge coming into contact with the patient&#39;s tissues.  
      While the present invention has been illustrated by description of various embodiments, it is not the intention of the applicants to restrict or limit the spirit and scope of the appended claims to such detail. Numerous other variations, changes, and substitutions will occur to those skilled in the art without departing from the scope of the invention. Moreover, the structure of each element associated with the present invention can be alternatively described as a means for providing the function performed by the element. It will be understood that the foregoing description is provided by way of example, and that other modifications may occur to those skilled in the art without departing from the scope and spirit of the appended Claims.