Patent Publication Number: US-2011054498-A1

Title: Endoscopic compression clip and system and method for use thereof

Description:
FIELD OF THE INVENTION 
     The present invention relates to endoscopic compression clips and a method and system for their use. 
     BACKGROUND OF THE INVENTION 
     Polyps are defined as growths or masses protruding from a mucous membrane of the body. They may occur in the mucous membrane of many different types of organs, such as the nose, mouth, stomach, intestines, rectum, urinary bladder, and uterus. Most polyps are benign and eventually stop growing, but some may ultimately become cancerous tumors. Colorectal or gastric cancers, often beginning as benign or precancerous polyps, can essentially be avoided if detected and treated in their early stages by performing a polypectomy. 
     Polypectomy is the medical term for removing polyps, particularly small polyps of the colon and stomach. These can be removed by using a biopsy forceps, which removes small pieces of tissue. Larger polyps are usually removed by putting a noose, or snare, around the polyp base or stalk and burning through the tissue with an electric instrument (cauterization). Other devices employ physical or electrical scraping of the lining of an organ, such as the colon, rectum or stomach, to remove the polyp. The severed polyps are usually retrieved for examination by a pathologist. 
     Complications, however, sometimes occur during polypectomies. Particularly problematic is bleeding induced by the device used to resect the polyp. The bleeding may be immediate or delayed. When bleeding is immediate, the vision of the physician is obscured and this may interfere with the completion of the surgical procedure, often an endoscopic procedure. When bleeding is delayed, additional surgical intervention, even possibly full invasive surgery may be required. 
     Mechanical surgical clips, particularly compression clips, for use in endoscopic surgery, including endoscopic polypectomies, are known. These clips inter alia are intended to achieve hemostasis as they apply constrictive forces to blood vessels so as to limit or interrupt blood flow. In effect, the bleeding vessel is ligated, or the tissue around the bleed site is compressed, ligating all of the surrounding vessels. However, these clips have drawbacks. 
     The typical clip is a two legged clip that is passed through an endoscope&#39;s working channel via a flexible delivery catheter. Because the clip needs to pass through the endoscope, the clip&#39;s size is limited. Size limitations prevent the clip from being able to effectively clamp off all of the blood vessel or vessels in the tissue or polyp&#39;s stalk to be resected. Additionally, the clip may be unable to provide sufficient clamping force because of its structural design. 
     An additional problem with these clips is that when delivering these clips to the wound site, good visualization of a bleeding vessel cannot be obtained. The endoscopist may be required to blindly attach the clip, resulting in an imprecisely performed procedure that requires guess work on the part of the endoscopist. Attaching a clip therefore may be unsuccessful during an initial attempt. 
     Finally, many clips slip off the tissue to which they have been attached and are compressing during, or subsequent to, a surgical procedure but prior to complete healing of the wound. All this leads to frequent follow-up endoscopic surveillance, adding to patient discomfort and extra costs to the health care system. 
     Other medical conditions also make use of compressive hemostatic clips. One such condition is peptic ulcer disease (PUD). This condition is associated with bleeding that can be fatal if not treated immediately. Internal hemorrhaging may be intense and a bleeding peptic ulcer can be a critical clinical event. 
     Suspected bleeding PUD patients can be diagnosed and treated endoscopically in an emergency room, an ICU or the GI suite. Many of the treatments used on PUDs, such as thermal cauterization, are similar to those applied when endoscopically removing polyps. The main goal in this procedure is to achieve rapid and effective hemostasis. As with polyp removal, delayed bleeding is a problem. 
     Other lesions, such as fistulas and organ perforations, the latter either naturally occurring or surgically produced, are also susceptible to bleeding. 
     Therefore, there remains a need for an endoscopic compression clip and a system and a method which would facilitate its use, particularly in endoscopically carried out polypectomies. The clip should be reopenable to ensure that if initial positioning is unsuccessful, the clip can be easily repositioned. In general, there is a need for such a clip, system and method that could be applied to stanch bleeding from all types of bodily lesions, naturally occurring or surgically generated. 
     TERMINOLOGY 
     “Proximal” relates to the side of an endoscope, a clip, a device or an element closest to the user, while “distal” refers to the side of the endoscope, the clip, the device or the element furthest from the user. 
     “Polyp” as used in the specification and claims herein is not intended to restrict the assembly, system, subsystems, elements and method discussed herein to polyps alone. Other types of suspect lesions may also be treated using the assembly, system, subsystems, elements and method discussed herein. 
     “Lesion”, in addition to its use herein to refer to many different types of localized pathological changes in a body organ or tissue, may also be used herein in place of the word “polyp” without any intent at differentiating between the two terms except where specifically indicated. Lesion also contemplates fistulas and organ perforations, either naturally occurring perforations or perforations produced during surgical procedures. 
     “Tissue” includes, but is not limited to, tissue of the gastrointestinal tract, and the vascular system. The assembly, system, subsystems, elements and method discussed herein may be used with tissue of any internal organ. 
     “Gastrointestinal tract” or its equivalents are used in the specification and claims without the intent of being limiting. Other organ systems, and lesions found therein, are also contemplated as being treatable with the assembly system, subsystems, elements and methods discussed in the present specification. 
     “Hinge” is a force applier and this latter term may be used herein interchangeably with hinge, hinge spring or clip hinge without any intent at differentiating between any of these terms, except where specifically indicated. 
     “Endoscope”, as used herein, should be construed as including all types of invasive instruments, flexible or rigid, having scope features. These include, but are not limited to, colonoscopes, gastroscopes, laparoscopes, and rectoscopes. Similarly, the use of “endoscopic” is to be construed as referring to all types of invasive scopes. 
     “Endoscopist” as used herein refers to any user of the clips and the clip system described herein. Besides a physician, it may refer to any other properly trained medical personnel. 
     “Applier” as used herein may be used interchangeably with the term “delivery system” without any attempt at differentiating between them. The applier delivers a compression clip assembly constructed according to an embodiment of the present invention, positions it and locks it around tissue of a lesion to be compressed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an endoscopic compression clip (ECC), often denoted herein as “clip”, for compression of a lesion, typically but without intending to limit the invention, a gastrointestinal (GI) lesion such as a polyp. 
     It is a further object of the present invention to provide a clip that can inter alia be used for hemostasis for mucosal or sub-mucosal defects, arteries, diverticula in the colon, for endoscopic marking, for anchoring or otherwise affixing jejunal feeding tubes, closing perforations, either naturally occurring or surgically produced, and multiple clip compression uses. 
     An additional object of the present invention is to provide a compression clip that reduces the incidence of procedure-related bleeding, irrespective of whether the bleeding is immediate or delayed. 
     Yet another object of the present invention is to provide a compression clip which is deployed in a controlled fashion and where the arms, that is the elongate members, of the clip can be reopened and repositioned any number of times prior to locking the clip into its final position. 
     Another object of the present invention is to provide a compression clip with a wide-angle opening between its elongate members 
     It is an object of the present invention to provide a system and method for use with an endoscopic compression clip constructed and operative according to embodiments of the present invention. 
     In one aspect of the present invention, there is provided a compression clip assembly for compressing tissue and operable by means of a user-operated applier. The assembly includes:
         A. an endoscopic compression clip having open and closed positions, wherein the clip includes:   (i) a pair of normally spaced apart elongate members each having an outward-facing surface, and having respective inward-facing opposing surfaces for holding and compressing tissue;   (ii) a hinge formed at least partly of a superelastic material and in operative mechanical connection with the elongate members; and   (iii) a lock region formed on the outer surface of each of the elongate members adjacent to the hinge, each of the lock regions being delimited by a first stop element proximate to the hinge and a second stop element distal from the hinge; and   B. a lock element for lockably engaging the lock regions so as to lock the clip in its closed position, the lock element and the lock regions being formed so as to facilitate relative translation of the lock element and the lock region until the lock element is positioned between the first and second stop elements.       

     In an embodiment of the compression clip assembly, the assembly further includes one or more third elements in each lock region. The one or more third elements are positioned between the first and second stop elements. Locking of the clip is effected when the one or more third elements are forcibly engaged by and pass within the lock element. This results in a required increase in force for further movement of the clip through the lock element so as to lock the clip with the lock element. 
     In another embodiment of the assembly, the lock element further includes one or more orientation teeth and one or more male yoke members for disengageably mating with the user-operated applier. 
     In yet another embodiment of the assembly, the lock element locks the clip after being positioned against the second stop elements. 
     In still another embodiment of the assembly, the hinge is configured as a substantially closed geometric shape enclosing an area large enough to accommodate a means for mechanical connection of the applier. 
     In a further embodiment of the assembly, the elongate members of the clip are formed of a superelastic material. 
     In yet another embodiment of the assembly, when the clip is locked, the ratio of the length of the elongate members of the clip extending past the lock element to the length of the lock element itself is from about 1 to about 7. 
     In another aspect of the invention, there is provided a system for applying a compression clip for compressing tissue. The system includes:
         A. a compression clip assembly, the assembly including:
           (a) an endoscopic compression clip having open and closed positions wherein the clip includes:
               (i) a pair of normally spaced apart, elongate members each having an outward-facing surface, and having respective inward facing opposing surfaces for holding and compressing tissue;   (ii) a hinge at least partly formed of a superelastic material and in operative mechanical connection with the elongate members; and   (iii) a lock region formed on the outer surface of each of the elongate members adjacent to the hinge, each of the lock regions being delimited by a first stop element proximate to the hinge and a second stop element distal from the hinge; and   
               (b) a lock element lockably engaging the lock regions so as to lock the clip in its closed position, the locking element and the lock regions being formed so as to facilitate relative translation of the lock element and the lock region until the lock element is positioned between the first and second stop elements;   
           B. an applier which includes:   (a) a housing having a periphery with a pair of slots symmetrically positioned therein and disengageably mateable with the lock element;   (b) a force transmitting element positioned within the housing and including two arms formed of a resilient material, each of the arms having a free end and insertion elements formed thereat for insertion into the hinge;   (c) a control means operative to selectably move the force transmitting element in the direction of the first stop elements and in the direction of the second stop elements of the clip; and   C. means for applying a resistive force operative to indicate that applying force to overcome the resistive force will lock the clip.   The control means may be selectably moved by a user in a selected one of the proximal and distal directions causing the force transmitting element to move by a preselected distance. The preselected distance is determined by the encounter of a resistive force when the clip is pulled in the proximal direction, the resistive force provided by the means for applying a resistive force so as to oppose movement of the clip within the lock element. When the force transmitting element is pulled so as to move the clip beyond the preselected distance overcoming the increased resistive force, the clip is positioned so that the lock element locks the clip in its closed position and the pair of elongate members of the clip are positioned adjacent to each other thereby to compress tissue held therebetween. The insertion elements pull away and disengage from the hinge and the force transmitting element arms exit the slots.       

     In another embodiment of the system, the lock element further includes one or more male yoke members and one or more orientation teeth and the housing further includes one or more yoke elements and one or more housing orientation spaces for disengageably mating with the one or more male yoke members and the one or more orientation teeth, respectively. 
     In yet another embodiment of the system, the resilient material of the force transmitting element arms is a superelastic material. When the force transmitting element is pulled so as to move beyond the preselected distance, the force transmitting element arms, confined in the housing, are operative to disengage from the hinge and to spring open and exit the housing slots after disengaging from the clip. 
     In still another embodiment of the system, when the force transmitting element is pulled so as to move beyond the preselected distance, the force transmitting element arms disengage from the clip and then are positioned to push against the one or more male yoke members of the lock element, thereby assisting in disengaging the locked clip assembly from the housing of the applier. 
     In yet another embodiment of the system, the clip includes one or more third elements. The one or more third elements are positioned between the first and second stop elements. The one or more third elements when encountered serve as the means for applying a resistive force, thereby indicating to the user imminent locking of the clip consequent to further application of force to the control means. 
     In yet another embodiment of the system, the arms of the force transmitting element include a pair of force transmitting element projections and each of the housing slots has a narrow proximal part and a wider distal part. At the junction of the wider and narrower parts, the parts form a step, the step serving as the means for applying a resistive force, thereby indicating to the user imminent locking of the clip consequent to further application of force to the control means. 
     In another embodiment of the system, the housing includes one or more yoke elements and the housing is constructed of a material that allows spreading of the one or more housing yoke elements when the force transmitting element projections enter the narrower proximal part of the slots so that the locked clip is more easily disengaged. 
     In still another embodiment of the system, the resilient material of the force transmitting element is a superelastic material. 
     In a further embodiment of the system, the open position of the clip forms an angle of at least about 45 degrees. 
     In still another embodiment of the system, the applier further includes an overtube for compressing the elongate members of the compression clip holding them in their closed position while the clip is brought to tissue to be compressed. 
     In another aspect of the invention there is provided a method for compressing tissue. The method includes the steps of:
         bringing a compression clip assembly, including a compression clip and a lock element, using an applier to tissue to be compressed;   opening and closing the compression clip, as often as necessary, around the tissue to be compressed until a proper positioning of the clip has been achieved;   locking the clip so that its elongate members are held adjacent to each other compressing the tissue held therebetween; and   freeing the locked clip from the applier by pulling on a compressed resilient force transmitting element of the applier so that it is brought to, and at least partly passes out of, slots in the wall of a housing of the applier removing the compressive force acting on the resilient force transmitting element allowing for disengagement of the clip from the applier.       

     In another embodiment of the method, the method further includes a step of drawing an overtube over the compression clip prior to the step of bringing and a step of pulling back the overtube and uncovering the clip, allowing the clip to return to its biased open position after the step of bringing. 
     In yet another embodiment of the method, the step of locking further includes a step of bringing the compression clip through the lock element so that the lock element passes over one or more projections on the clip after which the clip locks, the act of passing over the one or more projections after which the clip locks requires additional force by a user signaling to the user that passing the one or more projections will irreversibly lock the clip. 
     In still another embodiment of the method, the step of freeing further includes a step of moving the resilient force transmitting element so as to press against elements on the lock element mateable with elements on the housing of the applier to further assist in disengagement of the locked clip from the applier. 
     In yet another embodiment of the method, the step of locking further includes a step of bringing projections located on the resilient force transmitting element over a juncture formed by a narrower portion and a wider portion of the housing slots, the juncture requiring additional force by a user signaling to the user that passing the juncture will irreversibly lock the clip. 
     In still another embodiment of the method, the step of freeing includes a step of pulling the resilient force transmitting element so that the projections thereon enter the narrower part of the housing slots thereby locking the clip and facilitating disengagement of the locked clip from the applier by spreading apart elements of the housing mateably engaged with elements on the lock element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more fully understood and its features and advantages will become apparent to those skilled in the art by reference to the ensuing description, taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1A-1C  are side views of the actuator assembly, delivery system, and deployment assembly of an applier operative to deliver and activate a compression clip assembly constructed according to embodiments of the present invention, the clip being shown in its insertion, clip opening, and clip closing stages; 
         FIG. 1D  shows the mechanism of actuation of the actuator assembly shown in  FIGS. 1A-1C ; 
         FIGS. 2A-2E  show various views of a compression clip assembly, constructed according to an embodiment of the present invention; 
         FIGS. 3A and 3B  show two isometric views of a force transmitting element constructed in accordance with an embodiment of the present invention, one view of which shows the force transmitting element positioned in the housing of the applier&#39;s deployment assembly; 
         FIG. 4  is an isometric view of the endoscopic compression clip (ECC), clip lock element, and force transmitting element constructed according to an embodiment of the present invention; 
         FIGS. 5A-5D  show several views of the clip, clip lock element and distal end of the applier&#39;s deployment assembly at various stages of the ECC and clip lock element&#39;s operation according to the method of the present invention; 
         FIGS. 6A-6D  show different views of the pre-disengagement and disengagement steps of the compression clip assembly according to the present invention; 
         FIGS. 7A-7D  are additional views, generally cut-away views, of the clip, clip lock element and deployment assembly at various stages of operation according to the present invention; 
         FIGS. 8A and 8B  are two views of a clipped polyp using a locked endoscopic compression clip assembly constructed in accordance with an embodiment, and applied by the system, of the present invention; 
         FIGS. 9A-9D  show several isometric views of a compression clip assembly constructed according to a second embodiment of the present invention, the clip being presented at various stages of its operation; 
         FIGS. 10A-10C  show several views of a clip constructed according to a third embodiment of the present invention, the compression clip being presented at various stages of its operation; and 
         FIGS. 11A-11G  show several views of a compression clip assembly constructed in accordance with an embodiment of present invention and a second deployment assembly for deploying the compression clip assembly. 
     
    
    
     Similar elements in the Figures are numbered with similar reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides an endoscopic compression clip (ECC) for use in endoscopic procedures, inter alia for use in inducing hemostasis. The clip allows for being opened and closed by the endoscopist an unlimited number of times until satisfactory positioning of the clip is achieved. The clip may then be locked by a clip lock element disengageably connected to the housing of a deployment assembly. The deployment assembly is part of a clip delivery system herein denoted as an applier. The clip lock element is disengaged together with the clip from the deployment assembly of the applier and holds the clip in its locked closed position while the clip is compressing tissue. The clip and clip lock element together form what herein is denoted as the compression clip assembly. 
     The deployment assembly of the applier includes a force transmitting element. In what is described herein the force transmitting element will often be denoted and described as a fork element, typically, but without intending to limit the invention, having a forceps shape. It should readily be understood by persons skilled in the art that the fork element is exemplary only; other constructions of a force transmitting element may also be used. The force transmitting element is formed of a resilient material which allows it to remain in a closed configuration when under a compressive force supplied by the housing of the applier&#39;s deployment assembly. 
     The clip lock element is formed to contain one or more male yoke members and one or more orientation teeth which are mateably and disengageably joinable to one or more yoke elements of the housing of the applier&#39;s deployment assembly and the one or more housing orientation spaces thereof, respectively. Disengagement is effected by the force of pulling the clip in the proximal direction into the clip lock element until the lock element reaches distal stop projections on the clip. If disengagement does not occur immediately upon locking the clip, in some embodiments of the invention the arms of the fork element can be used to assist in disengaging the locked clip assembly as will be described below. 
     Disengagement of the clip from the applier&#39;s deployment assembly occurs only after the endoscopist is satisfied with the positioning of the clip around the tissue to be compressed and only after the lock element engages and lies entirely within the clip&#39;s locking region. The locking region is located on the outer surface of each elongate member of the clip adjacent to its hinge. In some embodiments, locking of the clip occurs only after the lock element passes over one or more projections positioned in the locking region near the hinge of the clip. These projections provide a resistive force that indicates that an increase in force is required for the lock element to be pulled past these one or more projections. They alert the endoscopist that application of an increased force will result in locking of the clip, allowing him to desist from applying such force preventing the clip from being locked unintentionally. 
     In other embodiments, locking of the clip occurs after one or more projections located on the arms of the force transmitting element pass a resistive step in release slots located in the housing of the deployment assembly. The resistive step provides a resistive force that indicates to the endoscopist that an increase in force is required for the clip to be pulled further into the lock element thereby locking the clip. This increase in resistive force prevents the endoscopist from locking the clip unintentionally. 
     It should be noted that in all embodiments of the invention, it is the lock element of the compression clip assembly that remains stationary while it is the clip that is pulled or pushed through the lock element. 
     Disengagement of the clip and clip lock element is effected when the arms of the force transmitting element, e.g. fork element, are brought adjacent to a region of the housing of the applier&#39;s deployment assembly having release openings, also denoted herein as release slots. These release openings act to release the compressive force operative on the resilient arms of the fork element. The release of the compressive force allows for the spreading apart of the fork element&#39;s arms. Insertion elements on the fork element&#39;s arms, also denoted herein as fork arm projections, then move out of the hinge loop region formed by the clip hinge and exit through the release openings, thereby disengaging the fork element from the clip. 
     Once the fork arm projections are released from the clip&#39;s hinge, the locked clip assembly detaches from the housing of the deployment assembly by separation of the lock element&#39;s one or more male yoke members from the housing&#39;s one or more yoke elements which hold them. In the case that the detachment is incomplete, the freed arms of the fork element may then be maneuvered to push against the one or more male yoke members of the lock element causing the lock element to separate from the housing of the applier&#39;s deployment assembly. 
     The point of attachment between the fork arms&#39; projections, that is the fork element&#39;s insertion elements, and the clip has been described above as a hinge loop. It should be understood that the clip&#39;s hinge may be constructed to form any closed shape with a hole in it in addition to a loop through which the fork arm insertion elements may be inserted. The closed shape, however, should have a sufficient area to accommodate and retain the fork arm insertion elements when inserted. The insertion elements are just one means for mechanical connection of the applier to the clip. It should be appreciated by persons skilled in the art that other such means are possible. 
     The clip, generally the clip hinge, is at least partly made of a superelastic material. This may be a shape memory alloy which exhibits superelasticity, such as a nickel-titanium (Ni—Ti) alloy. In some embodiments, the remainder of the clip may also be made of a superelastic material. The clip is biased to be in its open position with its arms spaced apart. In its open position, the arms of the clip form an angle equal to or greater than 45°. However, it should be understood that this angle is not intended to limit the invention. When nitinol is used in the hinge, its superelastic characteristic allows for greater elastic deformation, that is, deformation without plastic deformation, thereby allowing for the wide angle opening. 
     In some embodiments, the material used in the clip hinge may be a shape-memory material and not necessarily a superelastic material. 
     Nitinol or other superelastic material may also be used in the elongate members, herein also denoted as clip arms. When used in the clip arms, thicker tissue can be effectively compressed as the arms are superelastic and possesses a spring effect over a greater range of deflection then other materials. When nitinol is used only in the hinge, the clip arms may be made of plastic or any other stiff material and may be attached to the hinge by any of many methods known to those skilled in the art. 
     The present invention contemplates a working length ratio of the clip arms, that is, the elongate members, of from about 1 to about 7, more preferably from about 2 to about 6, and even more preferably from about 3 to about 5. The working length ratio (D/L) is defined herein as the ratio of the length of the clip from its distal end to the lock element when the lock element is in its locking position (D) to the length of the lock element (L). The large ratio provided by clips of the present invention allows for compression of thicker tissue (e.g. polyps with large stalks) and for closure of larger perforations. 
     In what is described herein, the use of the term open position and closed position for the clip refers to the position of the clip&#39;s elongate members. When the clip is in its open position the elongate members, the clip arms, are spaced apart. When the clip is in its closed position, the elongate members are not spaced apart and may be substantially adjacent to each other. 
       FIGS. 1A-1D , to which reference is now made, show various stages of the deployment of the compression clip of the present invention using a typical, but non-limiting, applier for delivering and applying the clip.  FIG. 1A  shows a side view of the applier with the clip  310  kept in its closed position by an overtube  205 , this being the position in which the clip is inserted into a body lumen using a typical, but non-limiting endoscope.  FIG. 1B  shows a side view of the applier when the clip  310  has been exposed by pulling the overtube  205  in the proximal direction allowing the clip to move to its biased open position. At this stage, the endoscopist can repeatedly open and close the clip until it is satisfactorily positioned around a lesion.  FIG. 1C  shows a side view of the applier and clip  310  when the clip has been closed. The actual disengagement of the locked clip from the applier&#39;s deployment assembly is not shown.  FIG. 1D  shows an enlarged cut-away view of the spring mechanism which advances and activates the clip via a control means, typically, but without intending to limit the invention, a control wire  201 , as in  FIG. 1D . 
     As shown in  FIG. 1A , endoscopic compression clip (ECC) system  400  is comprised of an actuator assembly  100 , a delivery section  200 , a deployment assembly  300  and a clip  310 . Clip  310  and deployment assembly  300  are discussed together in greater detail below. 
     Actuator assembly  100  may be constructed in a manner similar to conventional actuator assemblies of the type generally employed in endoscopic biopsy devices or in assemblies constructed for other similar applications. These are known to persons skilled in the art. Actuator assembly  100  allows the user to move a control wire  201  or other force transmitter, which is also denoted herein as a control means. Control wire  201  extends through shaft  204  ( FIGS. 1B and 1C ) to deployment assembly  300  at the distal end D of system  400 . Pushing control wire  201  moves clip  310  to, and out of, the distal end D of shaft  204  ( FIG. 1B ), while pulling wire  201  moves clip  310  in the proximal P direction. 
     Shaft  204 , typically a flexible coil, is designed to provide structural strength and to transmit a torque from its proximal end P to its distal end D. The flexible coil may be a conventional coil used in other biopsy devices and may, for example, comprise a single, coiled wire. The coiled wire may have a round, square or a rectangular cross section, and may be made of a biocompatible material such as, for example, stainless steel. Additional protective and low friction outer layers may be included on control wire  201  and/or shaft  204 , according to known methods of construction. Sliding over the distal end D of shaft  204  is overtube  205  ( FIGS. 1A and 1B ). Shaft  204  may alternatively be constructed as a tube, typically, but without limiting the invention, of plastic that is flexible enough to bend yet transmits force from its proximal to its distal end. 
     A deployment spring  104 , best seen in  FIG. 1D , may be provided within the body of actuator assembly  100 , positioned within control knob  102  to bias the knob, and thus the control wire  201 , toward a desired position. Control knob  102  mounted on actuator body  105  moves by sliding it along a guide slot  106 . Deployment spring  104  is in mechanical communication with control wire  201  through wire lock  202 . The endoscopist is able to manipulate control wire  201  by grasping thumb holder  101  and moving control knob  102  along guide slot  106 . 
     Spring  104  has a double purpose. First, spring  104  absorbs the relative movement between control wire  201  and shaft  204  produced by the curves of the body lumen into which the endoscope is inserted. This prevents clip  310  from inadvertently being pulled in the proximal direction. Second, deployment spring  104  increases the operating length of knob  102 . Deployment spring  104  amplifies the movement of knob  102  since the overall movement of clip  310  and control wire  201  between the clip&#39;s open and closed positions is very small. Pulling knob  102  in the proximal direction will not affect wire  201  until deployment spring  104  is fully compressed. Then, any additional movement of knob  102  in the proximal direction will pull wire  201  in that direction. 
     As shown in  FIG. 1D , positioned over wire  201  and in guide slot  106  is tensile spring  103  which keeps knob  102  under slight tension. This tension acting through wire  201  holds clip  310  against clip lock element  320  preventing undesired movement of the clip. 
     The proximal end of control wire  201  is attached to sliding control knob  102  using any of many methods known to persons skilled in the art. Stainless steel or other high yield biocompatible materials may be used to manufacture control wire  201  so that the structural integrity of the assembly is maintained. A superelastic material, such as nitinol, may also be used to form control wire  201 . 
     Several views of compression clip  310  and clip lock  320  constructed according to an embodiment of the present invention are shown in  FIGS. 2A-2E , to which reference is now made.  FIG. 2A  is a side view of clip  310  and clip lock element  320 ;  FIG. 2B  is a view of one side of the clip viewed from between the arms  318  of clip  310  along a cut through the J-J axis of  FIG. 2A ;  FIG. 2C  is a top view of clip  310  and lock element  320 ;  FIG. 2D  is a cut-away side view of clip  310  and lock element  320  along a cut through the I-I axis of  FIG. 2C ; and  FIG. 2E  is a side view of the hinge  314  region of clip  310  without clip lock element  320 . 
     Clip  310  is at least partially formed of a superelastic material. This may be a shape memory alloy which exhibits this property such as, but without intending to limit the invention, a nickel-titanium (Ni—Ti) alloy. In particular, but again without intending to limit the invention, clip hinge  314  may be formed at least partially of a superelastic material. The two elongate members or arms  318  of clip  310  contain teeth  311  for better grasping the tissue being held, and for preventing the tissue from slipping out of the arms of the clip when the tissue is grasped and the clip is locked. As best seen in  FIG. 2E , the proximal end of clip  310  includes clip arms  318 , clip hinge  314 , lock socket  316 , distal stop projections  313 , middle stop projections  319  and proximal stop projections  317 . Projections  313  and  317  may also be denoted herein as first and second stop elements, respectively. Lock socket  316  may also be denoted herein as lock region  316 . Lock region  316  is formed on the outer-facing surface of each of elongate members  318  adjacent to hinge  314 . The region is delimited by projections  313  and  317 . 
     Clip lock element  320  is shown in various views in  FIGS. 2A-2D . Lock element  320  contains one or more male yoke members  321  and one or more orientation teeth  322 . When clip lock element  320  locks clip  310  in its closed grasping position, the lock element moves from a position adjacent to proximal stop projections  317  over middle stop projections  319  ( FIG. 2E ) and is held in lock socket  316  ( FIGS. 2D and 2E ) of clip  310  between stop projections  313  and  317  ( FIG. 2D ). Lock element  320  can not move further in the distal direction because such movement is prevented by distal stop projections  313  ( FIG. 2E ). Similarly, when clip  310  is deployed and locked, lock element  320  can not fall off clip  310  by moving in the proximal direction—the direction of the clip hinge  314 ; that is prevented by proximal stop projections  317 . 
     Lock element  320  can not move past projections  313  and  317  because the inner diameter of lock element  320  is smaller than the distance between the projections on opposing clip arms. 
     As will be discussed further below, middle stop projections  319  allow for the opening and closing of clip  310  without it being locked. When control wire  201  is pushed in the distal direction as discussed below, force transmitting element, here a fork element,  340  ( FIG. 3A , for example), in mechanical communication with clip  310  and control wire  201  (described below), moves clip  310  in the distal direction. When clip  310  is being pulled in the proximal direction and moved relative to clip lock element  320 , clip lock element  320  encounters middle stop projections  319 . These projections transmit an additional resistive force to the endoscopist indicating that further advance of the clip through lock element  320  in the proximal direction would lock the clip. Therefore, middle stop projections  319  effectively act to prevent the clip from moving to its locked position within clip lock element  320 , in lock socket  316  between projections  313  and  317 , before the endoscopist is satisfied with the positioning of the clip around the lesion. Projections  319  are also denoted herein as a “means for applying a resistive force operative to indicate that applying force to overcome the resistive force will lock the clip”. 
     It should readily be appreciated that while force transmitting element  340  is herein described in terms of a fork element, other force transmitting elements may be designed and used. These function essentially as the fork element discussed herein. 
     There is a gradual narrowing  315  (best seen in  FIG. 2B ) of the width of clip  310  from the region immediately proximal to projections  317  and in the proximal direction, that is, in the direction of clip hinge  314 . This narrowing allows for a better mechanical connection between the fork arm projections  342  of fork element  340  (discussed below) and clip  310 . 
     It should be noted that the present invention contemplates embodiments where the clips may have fewer than three pairs of stop projections but at least a single pair of stop projections. It must have distal stop projections  313  to stop the lock in the distal direction. In some embodiments, the hinge can be designed in a way that allows it to serve as the proximal stop projection. 
     Connecting clip  310  to the remainder of ECC system  400  discussed in conjunction with  FIGS. 1A-1D  is force transmitting element, here a fork element,  340  shown in  FIGS. 3A and 3B . Fork element  340  is formed of two fork arms  341  each having at its distal end a fork arm projection  342  and is positioned within deployment assembly housing  330 . Fork element  340  as seen in  FIGS. 3A and 3B  has a generally forceps-like shape at the base of which are fork stopper projections  343 . These projections stop the fork element from moving further than necessary when the fork is being pulled in the proximal direction by control wire  201 . At the proximal end of fork  340 , the fork is in mechanical communication with control wire  201  which, as discussed above, extends from actuator assembly  100  ( FIGS. 1A-1D ) to fork element  340  in a wire cover  203  ( FIG. 1D ). A wire cover or a coated wire is used to decrease friction between wire  201  and spring shaft  204 . 
     Fork element  340  may be fabricated from any of many different resilient materials including superelastic materials. Accordingly, fork element  340  may at times be denoted herein as a “resilient element  340 ”. In some embodiments, superelastic materials, such as nitinol, may be used, while in other embodiments, more conventional resilient materials, for example stainless steel, may be used. In general, fork element  340  may be formed from any alloy and mechanically forced into its locked, that is clip holding, configuration once positioned in a housing of the deployment assembly. 
     In  FIG. 3B , fork  340  is seen in its most distal position. The fork cannot move further in the distal direction as it is being stopped by housing pin  334  of housing  330 . Housing  330  is best seen in  FIGS. 5A-5D . 
       FIG. 4 , to which reference is now made, illustrates how fork element  340  is attached to clip  310 . Fork arm projections  342  are positioned within the loop-like region formed by clip hinge  314 . The clip is shown in the Figure in its closed, but unlocked, position. In this Figure, fork arms  341  are positioned distally from release openings or slots  333 ; these openings or slots are not readily seen in the Figure but better seen elsewhere, for example,  FIGS. 5B ,  5 C and  5 D discussed below. Fork element  340  is in mechanical communication with control wire  201  within shaft  204  ( FIGS. 1B and 1C ). Activation of the system is effected as discussed in conjunction with  FIGS. 1A-1D  via wire  201 . In  FIG. 4 , housing  330  of the applier&#39;s deployment assembly in which fork element  340  is positioned is not shown. Housing  330  applies a compressive force on fork arms  341  of force transmitting element  340 , here a fork element. This force holds fork arm projections, also denoted herein occasionally as insertion elements,  342  of arms  341  within hinge  314 . 
       FIGS. 5A-5D , to which reference is now being made, is here presented to provide for a better understanding of  FIG. 4  and the method of the present invention.  FIG. 5A  is a view of the clip while it is still positioned in overtube  205  (not shown) during its insertion into a body lumen. The arms  341  of fork element  340  are visible and the fork arm projections  342  are positioned within the loop-like region formed by clip hinge  314 . The male yoke members  321  of lock element  320  are mateably held by yoke elements  331  of housing  330  while the orientation teeth  322  of clip lock  320  is mateably held by recesses, herein denoted as housing orientation spaces  332  of housing  330 . 
     Housing pin  334 , best seen in  FIGS. 4 ,  5 C and  5 D, which functions as a distal stop for fork element  340  also serves as an anti-rotation element for fork element  340  assuring that fork arms  341  are properly aligned with housing  330 . It orients fork element  340  within housing  330  to ensure that fork arms  341  are positioned so that they are in a correct orientation relative to release openings (slots)  333  of housing  330  thus allowing clip disengagement as will be further discussed below. Pin  334  further serves as a stopper preventing fork element  340  from fully exiting clip lock element  320  in the distal direction which would lead to unintentional and premature disengagement of the clip. 
       FIGS. 5B and 5C , to which reference is now made, show two views of clip  310  after it has been exposed by pulling overtube  205  ( FIG. 5B ) in the proximal direction. The clip is shown in its biased open position in  FIG. 5B . At this point, the endoscopist can repeatedly close and open the clip to position and reposition it around a lesion. In  FIGS. 5B and 5C , fork arm projections  342  are positioned in the loop-like region formed by hinge  314  best seen in  FIG. 4 . Clip lock element  320  is still in mateable connection with housing  330 . As noted above, one or more orientation teeth  322  orient the housing so that it is in proper mating position to mate with clip lock element  320 . In  FIG. 4 , pin  334  is positioned at the distal end of fork element  340  allowing further movement of fork element  340  in the distal direction. Proximal stop projections  317  and distal stop projections  313  are clearly shown in  FIGS. 4 and 5B . In  FIG. 5B , fork arms  341  are distally positioned vis-à-vis release openings  333  and they are compressed by housing  330 . 
       FIGS. 5C and 5D , to which reference is now made, show fork arms  341  first being brought adjacent to release openings  333  of housing  330  ( FIG. 5C ) and then being released from their compressed state, extending through release openings  333  ( FIG. 5D ). In  FIG. 5C , fork arms  341  are just beginning to exit recess openings  333 . After extending through release openings  333 , fork arms  341  may be used to push against male yoke members  321  of clip lock element  320 . This disengages clip lock element  320  from housing  330  by freeing male yoke members  321  from housing yoke elements  331 . In  FIG. 5D , clip  310 , which is closed and locked, is entirely disengaged from housing  330 . Clip lock element  320  has advanced passed middle stop projections  319  (obscured) resting between distal stop projections  313  and proximal stop projections  317  ( FIGS. 5C and 5D  and  FIGS. 2C and 2D ) in lock region, also denoted herein as lock socket,  316  ( FIG. 2E ). 
     It should be noted that  FIG. 5A  represents the first step in the use of the clip and clip lock element of the present invention and  FIGS. 5C and 5D  the penultimate and ultimate steps of the method.  FIG. 5B  represents only the first part of the intermediate stage of the method. Not shown here are the steps of repeatedly opening and closing the clip in attempts to satisfactorily position and clamp the tissue to be compressed. 
     In what herein is called, for reference, step A, fork element  340  of  FIG. 4  is pulled via control wire  201  in the proximal direction. Fork element  340  moves in that direction but its arms  341  are never brought to a position completely adjacent to release openings  333  as in  FIGS. 5C and 5D . This movement of fork element  340  in the proximal direction causes clip  310  to move further into clip lock element  320  forcing clip arms  318  to move from their spaced apart open position to their closed position as in  FIG. 5C . If the positioning of clip  310  is unsatisfactory, it is not locked and the fork is not pulled further in the proximal direction. Rather, the endoscopist pushes wire  201 , forcing fork  340  in the distal direction, for reference, denoted herein as step B. This causes clip  310  also to move in the distal direction and clip arms  318  to reopen and return to a position akin to  FIG. 5B . 
     It should be remembered that in all the pushing and pulling of wire  201 , clip lock element  320  is not moved. Clip  310  moves relative to lock element  320  as lock element  320  remains engaged to housing  330 . 
     Repositioning of clip  310  on the tissue to be compressed is effected and the clip is again provisionally brought to its closed position described in step A. If the repositioning is satisfactory, control wire  201  pulls fork element  340  further in the proximal direction to its position in  FIG. 5C  where fork arms  341  are adjacent to release openings  333 . There, they exit openings  333  and they may be used, if needed, to push male yoke members  321  of clip lock element  320  away from housing yoke elements  331 . This causes clip lock element  320  and housing  330  to separate as in  FIG. 5D . At separation, clip lock element  320  rests in lock socket, that is lock region,  316  between projections  313  and  317 . 
     When repositioning and closing the arms as in step A, the endoscopist readily avoids inadvertently locking clip  310  with clip lock element  320 . Before locking, the clip must be brought in the proximal direction so that lock element  320  is brought over middle stop projections  319 , best seen in  FIG. 2E , of clip  310 . The endoscopist will notice the increase in force required to pull clip  310  when projections  319  are about to pass under lock element  320 . This signals the endoscopist that continuing to pull on control wire  201  in the proximal direction will cause clip  310  to lock and disengage. Projections  319  represent the irreversible point in the locking of clip  310 . 
     The embodiment discussed above indicates that fork arms  341 , when emerging from release openings  333 , may be used to push against and disengage clip lock element  320  from housing  330 . However, it is contemplated that other methods may also be used to effect disengagement of lock element  320  from housing  330 . It is even contemplated that lock element  320  may by itself disengage from housing  330  after full deployment. This may occur because proximal stop projections  317  of clip  310  slightly separate the two sides of housing yoke elements  331  once they pass lock element  320 . This creates a large enough gap for male yoke members  321  of lock element  320  to disengage from housing yoke elements  331 . In effect, the proximal end of the clip applies a force on the yoke connection encouraging disengagement of the locked clip. 
       FIGS. 6A-6D , to which reference is now being made, show more detailed views than those shown in  FIGS. 5C-5D .  FIGS. 6A-6D  are isometric and side views of the step of disengagement shown in  FIGS. 5C and 5D . The numbered elements have all been discussed previously and accordingly will not be discussed again.  FIGS. 6A-6D  show fork arm projections  342  disengaged from clip hinge  314  and fork arms  341  moving through release openings, also denoted herein as release slots  333 .  FIG. 6D  shows a side view of the totally disengaged closed and locked clip  310  with fork arms  341  extending through release openings  333 . In  FIG. 6D  it can be seen that when the clip is locked clip lock element  320  is positioned forward of proximal stop projections  317  and up against distal stop projections  313 . Middle stop projections  319  are obscured by clip lock  320  in the Figures. 
     Reference is now made to  FIGS. 7A-7D .  FIGS. 7A-7C  show various cut-away essentially side views of clip  310  and the applier&#39;s deployment assembly  300 .  FIG. 7D  shows a side isometric view of the disengaged closed and locked clip  310  and deployment assembly  300 . All of the elements, their construction and their operation, have been discussed previously and will not be discussed again. In  FIGS. 7A and 7B , clip  310  is still engaged to clip deployment assembly  300  of the applier via fork arm projections  342 . In  FIG. 7C , the fork arm projections  342  have disengaged from clip hinge  314  and fork arms  341  are already exiting through release opening  333 . In  FIG. 7D , locked clip  310  is completely disengaged from deployment assembly  300  and fork arms  341  are extending out of release openings  333  in housing  330 . 
       FIGS. 8A and 8B  show two views of a locked compression clip assembly constructed according to an embodiment of the present invention and positioned on a stalk S of polyp P. Positioning, closing and locking of the clip may be effected as discussed previously. The construction of the clip may be as described above with reference to  FIGS. 2A-7D . Opening and closing of the compression clip can be effected as often as needed to arrive at adequate positioning around the polyp. Only then would a user lock the clip assembly. 
       FIGS. 9A-9D  show another embodiment of a clip constructed according to the present invention. Elements constructed and operative as in the clip embodiment of  FIGS. 2A-7D  have been given the same numbers. Equivalent, but slightly differently constructed, elements have been given a prefix digit of “1” with the number of the analogous part of the previous embodiment. Their function is essentially identical to the analogous part in the previous embodiment. 
       FIGS. 9A-9D  show a clip  1310  with broad clip arms, that is clip elongate members,  1318 , each arm having a clip arm projection  1371  at its distal end. Clip  1310  is constructed so as to have a broad surface area allowing better grasping of the tissue to be compressed. Overtube  1205  is of a non-uniform diameter with a broader distal end allowing the wider clip to be held in its closed position as it is advanced toward the tissue to be compressed. Overtube  1205  shown in  FIG. 9A  is truncated. It should readily be evident that it extends further in the proximal direction. 
       FIG. 9A  shows clip  1310  in its unlocked closed position within overtube  1205  as it is advanced to the lesion.  FIG. 9B  shows clip  1310  in its unlocked closed position, as in  FIG. 9A , but overtube  1205  is not shown.  FIG. 9B  shows clip  1310  engaged to deployment assembly housing  330  via fork arm projections  342  just as in the previously described embodiment. The substantially T-arm shaped distal end  1371  of clip  1310  is a gripping area. It has a larger gripping surface than in the previously described clip  310 .  FIG. 9C  shows clip  1310  being exposed after pulling overtube  1205  in the proximal direction and opened so that clip arms  1318  are spaced apart in the clip&#39;s biased open position.  FIG. 9D  shows clip  1310  after being disengaged from fork arms  341  and housing  330 . Disengagement is effected as in the embodiment discussed above. The disengaged clip in  FIG. 9D  is in its locked closed position. 
     In some versions of clip  1310 , clip  1310  may have distal stop projections  1313 , proximal stop projections  1317  and middle stop projections  1319  which function as their analogous parts in clip  310 . In other versions of clip  1310 , some of these projections may be absent as they may not be required. In these latter versions, geometry alone may prevent clip lock element  320  from sliding off clip  1310 . 
       FIGS. 10A-10C  show yet another clip constructed according to another embodiment of the present invention. Elements constructed and operative as in the clip embodiment of  FIGS. 2A-7D  have been given the same numbers. Equivalent, but slightly differently constructed, elements have been given a prefix digit of “2” with the number of the analogous part of the previous embodiment. Their function is essentially identical to the analogous parts in previous embodiments. 
     Clip  2310  is constructed as with the clip discussed in conjunction with  FIGS. 2A-7D . The difference is essentially a slightly enlarged face at the distal end of clip  2310 . Additionally, there is a distal protruding tooth  2351  at the distal end of each arm  2318  of the clip. Otherwise, the clip is constructed and operative as before including the presence of distal stop projections  2313 , middle stop projections  2319  and proximal stop projections  2317 . These projections function in locking and positioning the clip as described above in conjunction with the embodiment shown in  FIGS. 2A-7D . In this embodiment, as in the previous embodiment, the overtube has a non-uniform diameter with a broader distal end; this overtube is not shown in the Figures. 
       FIGS. 11A-11G , to which reference is now made, show yet another clip constructed according to an embodiment of the present invention applied in a slightly different manner. Elements constructed and operative as in the clip embodiment of  FIGS. 2A-7D  have been given the same numbers but with the addition of a prefix digit of “3”. Their function is essentially identical to the analogous parts in previous embodiments. 
     Clip  3310  and clip lock element  3320  are constructed as the clip and clip lock described in conjunction with  FIGS. 2A-7D  with the exception that there are no projections equivalent to middle stop projections  319  of clip  310 . Middle stop projections  319  indicated the irreversible point in the locking process. The function of middle stop projections  319  in the present embodiment is provided by fork arm protrusions  3390  on fork arms  3341 . Additionally, release slots  3333  in housing  3330  of the system are divided into wider slot regions  3333 D at the distal end of the slots and narrower slot regions  3333 P at the proximal end of the slots. This narrowing of the release slots creates a “step” which when encountered by fork arm protrusions  3390  indicates to the endoscopist that further motion of clip  3310  in the proximal direction will lock the clip. This “step” functions as middle stop projection  319  in clip  310 . In order to pass the “step” in the proximal direction and lock the clip the user must provide a noticeably increased force. The “step” is a second type of “means for employing a resistive force operative to indicate that applying force to overcome the resistive force will lock the clip”. 
     Applying an increased force allows fork arm protrusions  3390  to slide in the proximal direction into the narrower slot end  3333 P. If the endoscopist continues to pull control means, that is control wire,  3201  in the proximal direction, once clip  3310  is locked against distal stop projections  3313  situated on clip  3310 , as in previous embodiments, fork element, that is force transmitting element,  3340  detaches from clip  3310  as fork arms  3341  emerge from slot  3333 D. If made from a superelastic material, such as nitinol, fork arms  3341  may spring open; if arms  3341  are made from other resilient materials, such as stainless steel, the application of a force will slightly bend the arms leveraging their flexibility, so that fork arm projections  3342  can “exit” the clip&#39;s hinge loop. 
     The movement of protrusions  3390  in the narrow proximal end  3333 P of the slots leads to a spreading of housing yoke elements  3331 , as indicted by the diverging arrows in  FIG. 11F . This spreading of housing yoke elements  3331  facilitates detachment of locked clip  3310  from housing  3330 . If this is not enough to effect detachment, then, as in the other embodiments, fork element arms  3341  may be used to push against male yoke members  3321  of lock element  3320  to facilitate disengagement. As noted above, in this embodiment, fork element  3340 , including its arms, may be made of any resilient material, not necessarily superelastic materials, having sufficient material strength. 
     In the above discussion of the present invention, the invention has been described as being used in bowel polyp resections. It should be evident to one skilled in the art that other types of lesions, in other organs in other organ systems, can also be resected using the present invention with little or no modification. Such organs include, but are not limited to, the urinary bladder and other organs of the urinary tract, the uterus, the liver, the esophagus, the gall bladder, the lungs and the rectum. 
     The ECC and system for employing the clip may also be used in closing perforations, naturally occurring or resulting from surgical procedures, and fistulas. For such types of lesions, the method of use of the system and clip is essentially the same as discussed above and shown in the Figures. The method may be modified slightly as the particular lesion warrants. 
     Additionally, the ECC and system discussed herein above may be used to effect hemostasis in all bleeding situations, not only those resulting from resected GI polyps or bleeding peptic ulcers. Resection of any organ that leads to bleeding or any blood vessels that have been ruptured or are otherwise leaking may be treated as described herein. 
     It should be readily apparent to one skilled in the art that the device and method of the present invention can be used to compress animal tissue as well as human tissue, particularly, but without limiting the invention, tissue of other mammalian species. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. 
     It will be appreciated by persons skilled in the art that the present invention is not limited by the drawings and description hereinabove presented. Rather, the invention is defined solely by the claims that follow.