Patent Publication Number: US-10786254-B2

Title: Through the scope tension member release clip

Description:
PRIORITY CLAIM 
     The present application is a Continuation of U.S. patent application Ser. No. 13/463,560 filed on May 3, 2012, now U.S. Pat. No. 10,154,842; which claims priority to U.S. Provisional Application Ser. No. 61/482,429, entitled “Through the Scope Tension Member Release Clip,” filed on May 4, 2011. The entire disclosure of these applications/patents are expressly incorporated herein by reference. 
    
    
     BACKGROUND INFORMATION 
     Endoscopic procedures to treat abnormal pathologies of the gastro-intestinal (“GI”) canal system, of the biliary tree, of the vascular system and of various other body lumens are becoming increasingly common. The endoscope is basically a hollow tube that is placed at a desired location within the body to facilitate access to the relevant body ducts and lumens, etc. The endoscope itself cannot carry out many of the required procedures. To that end, the endoscope is fitted with a lumen, or internal channel, which permits the user to insert various medical devices therethrough to the location that requires treatment. Once the distal end of the inserted device has reached the tissue to be treated, it can be manipulated using controls which remain outside the body. 
     A hemostatic clipping tool is one of the devices which may be inserted through an endoscope so that treatment may be carried out. Hemostatic clips are deployed from the clipping tool and are used to stop internal bleeding by clamping together the edges of a wound. The clipping tool complete with clips attached to its distal end is inserted through the endoscope to the location of the bleeding. A clip is then remotely manipulated into position over the site of bleeding, clamped over the wound and detached from the tool. After a number of clips sufficient to stop the bleeding has been deployed, the tool is withdrawn from the patient&#39;s body through the endoscope. The size and shape of the clips and of the clipping tool are limited by the inner diameter of the endoscope&#39;s lumen, thus placing constraints on the design of the clip positioning and release mechanisms. 
     One challenge facing the endoscope operator is to properly position the hemostatic clips over the wound, so that closing the clips over the tissue will be effective in stopping the bleeding. If a clip is deployed improperly, additional clips may be required to stop the bleeding extending the time required for and the complexity of the procedure and leaving additional medical devices within the patient. It is also important for the device operator to be certain of the status of the clip during the deployment operation. For example, before withdrawing the tool from the endoscope, the operator should have positive indication that a clip has fully deployed, and has been released from the tool. At the same time the design of the tool should ensure that clips are fully released after they have been closed over the tissue. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is directed to an apparatus for deployment of a hemostatic clip comprising a handle assembly and a shaft connected to a distal portion of the handle assembly in combination with a clip assembly releasably coupled to a distal portion of the shaft, the clip assembly including clip arms and a capsule cooperating with the clip arms to provide a first user feedback indicating a decision configuration of the clip assembly and a control wire including a ball connector, the control wire extending from the handle assembly and coupled to the clip assembly by the ball connector to maintain the clip assembly coupled to the shaft, wherein the ball connector is detachable from the clip assembly to provide a second user feedback indicating separation of the clip assembly from the shaft. 
     In a different aspect, the present invention is directed to a clip assembly deployable through an endoscope, comprising a capsule releasably connected to a bushing of an elongated clip deployment device, clip arms slidable within the capsule between a distal open configuration and a proximal closed configuration, a tension member slidable with the clip arms, urging the clip arms in the open configuration, and a yoke slidable within the capsule, releasably connected to the tension member at one end, and connected to a control wire of the clip deployment device at another end. In the invention, distal movement of the control wire slides the clip arms in the open configuration, and proximal movement of the control wire slides the clip arms in the closed configuration. 
     In a further embodiment, the invention is directed to a method for hemostatic clipping through an endoscope. The method includes providing a shaft section connected to a clip assembly of a clipping device insertable through an endoscope working lumen, providing a handle assembly attached to the shaft section, the handle assembly allowing longitudinal movement of a control wire, and providing a connection between a distal end of the control wire and clip arms of the clip assembly, whereby longitudinal movement of the control wire moves the clip arms between an open and a closed configuration. The method also includes giving a first user feedback indicating a decision configuration of the clip assembly, and giving a second user feedback indicating separation of the clip assembly from the shaft section. 
     The present invention is further directed to an apparatus for deployment of a hemostatic clip comprising a clip assembly releasably coupled to a distal portion of a shaft, wherein the clip assembly includes a capsule releasably coupled to the shaft, clip arms slidably received within the capsule and cooperating with the capsule to provide a first user feedback indicating a decision configuration of the clip assembly and a yoke slidably received within the capsule, the yoke including proximal and distal portions releasably and rotatably connected to one another via a first control wire, a distal end of the distal portion being connected to proximal ends of the clip arms. A second control wire extends from the handle assembly and is coupled to a proximal end of the second portion to move the clip assembly between open and closed configurations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a clipping device according to an exemplary embodiment of the present invention; 
         FIG. 1A  shows a detail view of an exemplary clip assembly of the clipping device; 
         FIG. 2  is a schematic side view of the embodiment shown in  FIG. 1 , with an outer sheath; 
         FIG. 3  is a cut away side view of the shaft section according to an embodiment of the present invention; 
         FIG. 4  is a cross sectional view of the shaft section shown in  FIG. 3 ; 
         FIG. 5  is a detail view of the distal end of the control wire according to an embodiment of the present invention; 
         FIG. 6  is a perspective view of an outer sheath according to an embodiment of the present invention; 
         FIG. 7  is a cross sectional exploded view of the handle of the outer sheath shown in  FIG. 6 ; 
         FIG. 8  is a perspective view of an outer sheath lock according to an embodiment of the present invention; 
         FIG. 9  is a cross sectional side view of a distal end of a clipping device according to an embodiment of the present invention; 
         FIG. 10  is a cross sectional top view of a distal end of the clipping device shown in  FIG. 9 ; 
         FIG. 11  is a perspective view of the distal end of the clipping device shown in  FIG. 9 ; 
         FIG. 12  is a top view of the clip aims according to an embodiment of the present invention; 
         FIG. 13  is a perspective view of the clip arms shown in  FIG. 12 , according to an embodiment of the present invention; 
         FIG. 14  is a perspective view of a capsule according to an embodiment of the present invention; 
         FIG. 15  is a cross sectional side view of the of the capsule shown in  FIG. 14 ; 
         FIG. 16  is a top view of the distal end of a clipping device according to an embodiment of the present invention; 
         FIG. 17  is a side view of the distal end shown in  FIG. 16 ; 
         FIG. 18  is a perspective view of a clip arm according to an embodiment of the present invention; 
         FIG. 19  is a side view of the clip arm shown in  FIG. 18 ; 
         FIG. 20  is a top view of the clip arm shown in  FIG. 18 ; 
         FIG. 21  is a perspective view of a bushing according to an embodiment of the present invention; 
         FIG. 22  is a cross sectional side view of the bushing shown in  FIG. 21 ; 
         FIG. 23  is a perspective view of a wire stop according to an embodiment of the present invention; 
         FIG. 24  is a schematic side view of a clip assembly detached from a bushing, according to an embodiment of the present invention; 
         FIG. 25  is a side view of a tension member according to an embodiment of the present invention; 
         FIG. 26  is a top view of the tension member shown in  FIG. 25 ; 
         FIG. 27  is a top view of a yoke according to an embodiment of the present invention; 
         FIG. 28  is a perspective view of the yoke shown in  FIG. 27 ; 
         FIG. 29  is a top view of a yoke with a control wire according to an embodiment of the present invention; 
         FIG. 30  shows a cross-sectional side view of a clipping device according to another embodiment of the present invention; 
         FIG. 31  shows a side view of a yoke and control wires attached thereto according to the embodiment of  FIG. 30 ; 
         FIG. 32  shows a first cross-sectional side view of a control wire and yoke assembly according to another embodiment of the present invention; 
         FIG. 33  shows a second cross-sectional side view of the control wire and yoke assembly shown in  FIG. 32 ; 
         FIG. 34  shows a cross-sectional side view of a control wire and yoke assembly according to yet another embodiment of the present invention; 
         FIG. 35  shows a second cross-sectional side view of the control wire and yoke assembly shown in  FIG. 34 ; 
         FIG. 36  shows a cross-sectional side view of a control wire and yoke assembly according to yet another embodiment of the present invention; 
         FIG. 37  shows a second cross-sectional side view of the control wire and yoke assembly shown in  FIG. 36 ; and 
         FIG. 38  shows a partial cross-sectional view of an insert for the assembly of  FIG. 36 . 
     
    
    
     DETAILED DESCRIPTION 
     Hemostatic clips are used routinely to stop bleeding from openings created during surgery as well as wounds resulting from other trauma to tissues. In the simplest form, these clips grasp the tissue surrounding a wound and bring the wound&#39;s edges together, to allow the natural scarring process to heal the wound. In endoscopic hemostatic clips are used to stop internal bleeding due resulting from surgical procedures and/or tissue damage from disease, etc. Specialized endoscopic hemostatic clipping devices are used to bring the clips to the desired location within a patient&#39;s body and to position and deploy the clip at the appropriate place on the tissue. The clipping device is then withdrawn, leaving the clip within the patient. 
     Endoscopic hemostatic clipping devices are designed to reach affected tissues deep within a patient&#39;s body, such as within the GI tract, the pulmonary system, the vascular system or within other lumens and ducts. During the procedures to treat those areas, an endoscope is generally used to provide access to and visualization of the tissue which is to be treated. The clipping device may, for example, be introduced through a working lumen of the endoscope. The design and construction of such a “through the scope” endoscopic hemostatic clipping device presents several challenges. The endoscopic clipping device has to be sufficiently small to fit in the lumen of an endoscope and, at the same time, must be designed to provide for the positive placement and actuation of the hemostatic clip. Feedback to the operator is preferably also provided so that the operator will not be confused as to whether the hemostatic clip has been properly locked in place on the tissue and released from the device before the device itself is withdrawn through the endoscope. 
       FIG. 1  shows a side elevation view of a through the scope hemostatic clipping device according to an exemplary embodiment of the present invention. This device is a hand operated tool that is used to insert a hemostatic clip through an endoscope lumen, position the clip over a wound, clamp it and deploy it over the affected tissue. The tool is further designed to release the hemostatic clip once it has been clamped in place, and to be withdrawn through the endoscope. To more clearly explain the operation and construction of the exemplary device, it may be divided into three principal components. As shown in  FIG. 1 , the hemostatic clipping device  100  comprises a handle assembly  102 , a shaft section  104 , and a clip assembly  106 . A detailed view of the clip assembly  106  is shown  FIG. 1A . 
     Handle assembly  102  forms the component that supplies a mechanical actuation force to deploy and clamp the clip. In this embodiment, the device is hand operated (i.e., the user&#39;s hands provide the force required to carry out all the functions related to the hemostatic clip). The handle assembly  102  may be constructed in a manner similar to conventional handle assemblies of the type generally employed in endoscopic biopsy devices or in similar applications. The handle assembly  102  allows the user to move a control wire  118  or other force transmission member, which extends through the shaft section  104  to the clip assembly  106  at a distal end of the device  100 . The handle assembly  102  comprises a handle body  108  which can be grasped by the user to stabilize the device and apply a force to it. A sliding spool  110  is connected to a control wire  118 , so that the user can easily pull or push the wire  118  as desired. 
     As shown in  FIGS. 1 and 2 , a sliding spool  110  is mounted on the handle body  108  so that it can slide along a slot  116 , which maintains its position within the handle assembly  102 . Because the sliding spool  110  is connected to the control wire  118 , the user may manipulate the control wire  118  by grasping the handle body  108  and moving the sliding spool  110  along the slot  116 . A return spring  112  may be provided within the handle body  108  to bias the sliding spool  110 , and thus the control wire  118  toward a desired position. In the present embodiment, the sliding spool  110  is biased to the proximal position. The handle assembly  102  may also include a connection portion  114 , which receives the control wire  118  and attaches the shaft section  104  to the handle assembly  102 . 
     The shaft section  104  mechanically connects the handle assembly  102  to the clip assembly  106  and, together with the clip assembly  106 , is designed to be inserted into a lumen of an endoscope. As shown in  FIGS. 3 and 4 , the shaft section  104  comprises an outer flexible coil  130  which is designed to transmit a torque from the proximal end to the distal end of the device  100  and to provide structural strength to the shaft section  104 . The coil  130  may be a conventional coil used in 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 the shaft section  104 , according to known methods of construction. 
     The control wire  118  transmits mechanical force applied to the handle  102  to the clip assembly  106 . The control wire  118  has a proximal end which is attached to a movable part of the handle  102 , such as the sliding spool  110 , using known methods. Stainless steel or other high yield biocompatible materials may be used to manufacture the control wire  118 , so that the structural integrity of the assembly is maintained. It is also important to prevent stretching of the control wire  118  when under tension since, if the wire stretches, the handle  102  will have to travel a greater distance to carry out a desired operation. As shown in  FIG. 5 , the distal end of the control wire  118  ends in a ball  140  which is used to connect the control wire  118  to the appropriate elements of the clip assembly  106 , as will be described below. In this embodiment, the diameter of the control wire  118  is substantially constant from a proximal end thereof to a proximal end of a distal tapered section  144 . The ball  140  may have a diameter which is greater than the diameter of the control wire  118 , to facilitate attachment to a yoke  204 . The control wire  118  may extend the length of the device  100 , from the yoke  204  to the sliding spool  110 , and slides longitudinally through the device  100 . It may be made, for example, of stainless steel or other biocompatible metal. 
     The control wire  118  may also include a reduced diameter section  142  designed to fail when a predetermined tension is applied thereto through the handle assembly  102 . The tapered section  144  may be used to transition between the main body of the control wire  118  and the reduced diameter section  142 , without steps or other discontinuities which may concentrate stress and make the fracture point more unpredictable. As will be described in greater detail below, one purpose of the reduced diameter section  142  is to facilitate the release of a hemostatic clip from the hemostatic clipping device  100  once the clip has been properly deployed. It will be apparent to those of skill in the art that the location of the reduced diameter section  142  the along control wire  118  may be varied to take into account specific requirements of the device  100 . 
     An inner sheath  132  may be used in the construction of the shaft section  104 , as shown in  FIGS. 3 and 4 . The inner sheath  132  provides a low friction bearing surface disposed between the outer diameter of the control wire  118 , and the inner diameter of the shaft section  104 . The inner sheath  132  may be formed of a low friction material such as, for example, Teflon™, HDPE or Polypropylene. In one exemplary embodiment, the inner sheath  132  is slidable within the shaft section  104 , and the control wire  118  is slidable within the inner sheath  132  forming a low friction system of multiple bearing surfaces. To further reduce friction, a bio-compatible lubricant may be applied to the inner and outer surfaces of the inner sheath  132 , along the length of the shaft section  104 . For example, silicone lubricants may be used for this purpose. 
     A slidable over-sheath  150  may be included in the design of the shaft section  104 , as shown in  FIGS. 1 and 2 . The over-sheath  150  is designed to protect the inner lumen of the endoscope from the metal clip assembly  106  and from the metal coil  130  while the hemostatic clipping device  100  passes through the endoscope&#39;s lumen. After the clipping device  100  and, more specifically, after the clip assembly  106  has passed through the endoscope, the over-sheath  150  may be withdrawn to expose the distal portion of the clipping device  100 . The over-sheath  150  may be formed, for example, as a single lumen plastic extrusion element slidable over the distal portions of the clipping device  100  to selectively cover and uncover the clip assembly  106 . In one embodiment, the over-sheath  150  is formed of a low friction polymer such as, for example, Teflon™, HDPE, Polypropylene, or similar materials. 
     The over-sheath  150  may include a grip portion  152  and an elongated body  154 . The grip portion  152  is designed as a handle making it easier for the user to slide the over-sheath  150  over the shaft of the clipping device  100 . In one exemplary embodiment, the grip portion  152  is made of a rubber-like material to provide a good gripping surface for the user. For example, an injection moldable polymer such as TPE may be used to construct the grip portion  152 . The elongated body  154  may be formed as a substantially cylindrical shell surrounding the shaft of the clipping device  100 . The elongated body  154  may be attached to the grip portion  152  using conventional methods as would be understood by those skilled in the art. 
     As shown in  FIGS. 6 and 7 , an exemplary grip portion  152  comprises a central hollow channel  160  that may be used to receive the shaft of the clipping device  100 . The central hollow channel  160  is aligned with the elongated body  154  to provide a continuous channel containing the shaft of the clipping device  100 . The material of the grip portion  152  may have a high coefficient of friction, so that an interference fit is possible between the central hollow channel  160  and the shaft of the clipping device  100  without the use of adhesives or mechanical fastening devices. In one embodiment, friction bosses  158  may be provided on an inner diameter of the hollow channel  160  to provide additional friction between the shaft of the clipping device  100  and the over-sheath  150  assembly. The friction bosses  158  may be formed, for example, as protrusions extending from the inner diameter of the over-sheath  150  and may have a variety of stubby or elongated shapes. The amount of friction between these two components may be balanced so that no unwanted relative movement takes place while, at the same time, making it relatively easy for the user to slide the over-sheath  150  proximally and distally when necessary. 
     A sheath stop  156  may be provided for the clipping device  100  to prevent the over-sheath  150  from sliding away from the distal end while the clipping device  100  is inserted in the endoscope. As shown in the exemplary embodiment of  FIGS. 2 and 8 , the sheath stop  156  physically blocks the grip portion  152  from sliding proximally to prevent the over-sheath  150  from being withdrawn and exposing the clip assembly  106 . The sheath stop  156  is designed to easily snap in place near the proximal end of the shaft section  104  where it can be reached and manipulated by the operator during the surgical procedure. Once the clip assembly  106  has been inserted in the endoscope and has reached the desired location in the patient&#39;s body, the sheath stop  156  may be removed from the shaft section  104  so that the user can move the grip portion  152  proximally to uncover the clip assembly  106 . 
     The connection between the sheath stop  156  and the shaft section  104  may include, for example, pairs of opposing fingers  162 ,  164  that are designed to snap over the shaft section  104 . The fingers  162 ,  164  cooperate to securely and releasably hold the body of the shaft section  104  therebetween. The fingers  162 ,  164  respectively comprise guide portions  170 ,  172 ; shaft channel portions  166 ,  168 ; and blocking portions  174 ,  176 . Insertion of the sheath stop  156  on the elongated body  154  is accomplished by pressing the body of the shaft section  104  between the guide portions  170 ,  172 , to spread the fingers  162 ,  164  and allow further insertion of the shaft  104  between the fingers  162 ,  164 . The guide portions  170 ,  172  and the blocking portions  174 ,  176  are shaped so that insertion of the shaft section  104  towards the channel portions  166 ,  168  requires less effort than moving the shaft section  104  in the opposite direction. 
     Once shaft section  104  has been placed within the channel portions  166 ,  168 , the fingers  162 ,  164  snap back to their non-spread position and retain the shaft section  104  in place therebetween. The shaft section  104  is removed by pulling the sheath stop  156  away from the shaft section  104 . Due to the shape of the blocking portions  174 ,  176 , removing the shaft section  104  requires the application of more force than does insertion thereinto. Stops  180  may also be provided on the sheath stop  156  to limit the movement of the shaft section  104  towards the grasping portion  161  to prevent damage to the device that may be caused by excessive spreading of the fingers  162 ,  164 . The sheath stop  156  may be formed of a resilient material, such as a polymer, and may be manufactured by injection molding. 
     The clip assembly  106  is disposed at the distal end of the clipping device  100 , and contains the mechanism that converts the proximal and distal movement of the control wire  118  into the actions necessary to deploy and release a hemostatic clip  90 .  FIGS. 9, 10 and 11  show, respectively, side, top and perspective views of the distal end of the clipping device  100 , including the clip assembly  106  having clips in the folded configuration. This configuration is used, for example, to ship the clipping device  100  and to insert the clipping device  100  through the lumen of an endoscope. Some of the components of the clip assembly  106  include a capsule  200  which provides a structural shell for the clip assembly  106 , the clip arms  208  which move between open and closed positions, a bushing  202  attached to the distal end of the control wire  118 , and a yoke  204  adapted to connect the capsule  200  to the control wire  118 . 
     As depicted, the proximal end of the capsule  200  slides over the distal end of the bushing  202 . A locking arrangement between these two components is provided by capsule tabs  212 , which are designed to lock into the bushing  202  so that mechanical integrity is temporarily maintained between the capsule  200  and the bushing  202 . Within the capsule  200  are contained a yoke  204  and a tension member  206  which transmit forces applied by the control wire  118  to the clip arms  208 . The ball  140  formed at the distal end of the control wire  118  is mated to a receiving socket  210  formed at the proximal end of the yoke  204 . A male C-section  214  extending from the tension member  206  is received in a corresponding female C-section  216  formed in the yoke  204 , so that the two components are releasably connected to one another, as will be described below. The clip arms  208  in the closed configuration have a radius section  300  which is partially contained within the capsule  200  to prevent opening of the arms. Each of the clip arms  208  goes over the tension member  206  and has a proximal end  222  which slips under a yoke overhang  254 , to further control movement of the arms  208 . 
       FIGS. 12 and 13  show a top and a perspective view of the clip assembly  106  in an open configuration with the clip arms  208  in a fully open position. The open configuration is obtained when the sliding spool  110  shown in  FIG. 1  is moved distally so that the ball  140  of the control wire  118  pushes the assembly containing the yoke  204  and the tension member  206  forward, sliding within the capsule  200 . As will be described below, the distal ends of the clip arms  208  are biased toward the open position and revert to this position whenever they are not constrained by the capsule  200 . In the exemplary embodiment, a maximum opening of the clip arms  208  occurs when the clip arms  208  ride over the folded distal folding tabs  220  which extend from the distal end of the capsule  200 , as shown in  FIGS. 14 and 15 . In this embodiment, the tabs  220  provide a cam surface, and the clip arms  208  act as cam followers, being deflected by the tabs  220 . In addition, the folding tabs  220  may also provide a distal stop for the tension member  206 , to retain it within the capsule  200 . Thus, by moving the sliding spool  110  distally, the user opens the clip arms  208  to prepare to grasp tissue therebetween. 
     When the sliding spool  110  is moved proximally by the user, the assembly within the capsule  200  also moves proximally and the clip arms  208  are withdrawn within the capsule  200 . As the clip arms  208  move proximally within the capsule  200 , clip stop shoulders (CSS)  222  contact a distal portion of the capsule  200 , for example, the folded tabs  220 . This interaction of the CSS  222  with the capsule  200  provides to the user a first tactile feedback in the form of increased resistance to movement of the sliding spool  110 . This feedback gives to the operator a positive indication that further movement of the handle control will cause the hemostatic clip  90  to be deployed from the clip assembly  106 . The operator may then decide whether the current position of the clip  90  is acceptable or not. If the position is acceptable, the operator can deploy the clip  90  by continuing to move the sliding spool  110  with increased proximal pressure to cause the clip arms  208  to close on the tissue. If not, the operator can move the sliding spool  110  distally to re-open the clip arms  208  and extend them out of the capsule  200 , reposition the clip  90 , and repeat the above steps to close the clip  90  at a more appropriate location. 
     When the user determines that the clipping device  100  is positioned correctly, the proximal pressure on the sliding spool  110  may be increased to continue deployment of the hemostatic clip  90  from the clip assembly  106 .  FIGS. 16 and 17  show respectively a top and side view of the clipping device  100  in this condition. As the proximal tension on sliding spool  110  is increased, the control cable  118  pulls the yoke  204  proximally, away from the tension member  206 . The tension member  206  is firmly attached to the clip arms  208  which are prevented from moving proximally by the interaction of the CSS  222  with the folded tabs  220 . If sufficient pulling force is applied to the yoke  204 , the male C section  214  of the tension member  206  yields and loses integrity with the female C section  216  of the yoke  204 . This can occur because, in the exemplary embodiment, the tension member  206  is formed of a material with a lower yield strength than the material of the yoke  204 . 
     The force required to break the tension member  206  away from the yoke  204  may be tailored to achieve a desired feedback that can be perceived by the user. The minimum force required to break the tension member  206  free of the yoke  204  may be selected so that a tactile feedback is felt by the user, to prevent premature deployment of the hemostatic clip  90  while a maximum force may be selected so that other components of the linkage between the sliding spool  110  and the clip aims  208  do not fail before the male C section  214  and the female C section  216  disconnect from one another. In one exemplary embodiment, the tension force necessary to disconnect the two components may be in the range of approximately 4 lbf to about 12 lbf. This range may vary depending on the size of the device and the specific application. To obtain this force at the interface of the male and female C sections  214 ,  216  a larger force will be applied by the user at the sliding spool  110 , since friction within the device may cause losses along the long flexible shaft. 
     When the male C section  214  of tension member  206  yields, several events take place within the device  100  nearly simultaneously. More specifically, the yoke  204  is no longer constrained from moving proximally by the CSS  222  abutting the capsule  200 . Thus, the yoke  204  travels proximally until coming to rest against a distal bushing shoulder  250 . The tension member  206  is not affected by this movement since it is no longer connected to the yoke  204 . The proximal ends  252  of the clip arms  208  are normally biased away from a center line of the device  100  and are no longer constrained by the yoke overhangs  254 . Accordingly, the clip latches  302  are free to engage the latch windows  304  of the capsule  200 , thus maintaining the integrity of the capsule-clip arms combination after deployment. Details of the capsule  200  are shown in  FIGS. 14, 15  and details of the clip arms  208  are shown in  FIGS. 18, 19 and 20 . 
     As the yoke  204  moves proximally to abut against the bushing  202 , the capsule tabs  306  are bent away from the centerline of the capsule  200  by the cam surfaces of the yoke  204 . As a result, the capsule tabs  306  are no longer engaged to the corresponding bushing undercuts  350 , shown in the side and perspective views of the bushing  202  depicted in  FIGS. 21, 22 . Since the capsule  200  and the bushing  202  (which is securely connected to shaft section  104 ) are no longer connected, the clip assembly  106  is prevented from being released from the shaft section  104  only by its connection to the ball  140  of the control wire  118 . 
     A further result of moving the yoke  204  against the distal bushing shoulder  250  of the bushing  202  is that the distal end of the wire stop  360  (shown in  FIGS. 12, 16 ) is placed near the proximal bushing shoulder  364  (shown in  FIG. 22 ). The flared fingers  362  located at the distal end of the wire stop  360 , better shown in  FIG. 23 , are compressed as they pass through the central ID of the bushing  202 , but return to their normally biased open position (shown in  FIG. 23 ) after passing past the proximal bushing shoulder  364 . Further distal movement of the sliding spool  110  is thus prevented since that movement would engage the fingers  362  of the wire stop  360  with the proximal bushing shoulder  364 . This feature prevents the clip assembly  106  from being pushed away from the bushing  202  before the ball  140  is separated from the control wire  118 , as will be described below. 
     The wire stop  360  comprises a tube with a first slotted and flared end attached to the control wire  118  by conventional means. As shown in  FIG. 23 , the slots impart flexibility to the device so it can easily pass through the central lumen of the bushing  202 . Flared fingers  362  are formed by the slots, and engage the proximal bushing shoulder  364 . The wire stop  360  is made of a material that is biocompatible and that has enough resilience so that the fingers  362  re-open after passage through the bushing  202 . For example, stainless steel may be used for this application. 
     One feature of the exemplary embodiment of the invention described above is that the user receives both tactile and auditory feedback as the clip assembly  106  is deployed and released. The separation of the tension member  206  from the yoke  204  produces a small clicking noise and a tactile feel that is perceptible while holding the handle assembly  102 . The change in axial position of the sliding spool  110  is thus augmented by the changes in resistance to its movement and by the clicking sound and feel through the start and stop of the movement. As a result, the user is always aware of the status of the clip assembly  106 , and the inadvertent deployment of a hemostatic clip  90  in an incorrect location is made less likely. It will be apparent to those of skill in the art that the order of male and female connectors in the device may be reversed or changed without affecting the operation of the device. 
     It may be beneficial for the user to be certain that the clip assembly  106  has been deployed before the rest of the clipping device  100  is removed from the endoscope. Injury to the tissue being treated could result if the clipping device  100  is removed from the operative site when the hemostatic clip  90  is only partially deployed. Accordingly, a large tactile feedback may be incorporated, to augment the auditory and tactile feedback stemming from the separation of the yoke  204  from the tension member  206 .  FIG. 24  depicts the condition where the clip assembly  106  separates from the rest of the clipping device  100 . According to the described embodiment, this second user feedback is obtained by designing the control wire  118  so that it will separate from the end ball  140  when a predetermined tension is applied to it. In other words, the ball  140  of the control wire  118  is mechanically programmed to yield and separate from the body of the control wire  118  when a pre-set tension is applied thereto. The size of the reduced diameter section  142  can be selected so that, when the user continues to move the sliding spool  110  proximally as the programmed yield tension is reached, the ball  140  detaches from the tapered section  144  and provides a large tactile feedback to the operator. 
     When the ball  140  detaches, the sliding spool  110  bottoms out at the proximal end of the handle  108 , such that a full stroke of the handle assembly  102  is reached. The tension required to cause the reduced diameter section  142  to yield and release the ball  140  may vary over a range of values. However, for best results the force should be greater than the tension force required for the male C section member  214  to separate from the yoke  204 . If this condition is not satisfied, a situation may occur where the clip assembly  106  is locked in place on the patient&#39;s tissue, but cannot be released from the clipping device  100 . It will be apparent that this situation should be avoided. In one exemplary embodiment, the tension force required to separate the ball  140  from the body of the control wire  118  is in the range of between about 10 lbf and 20 lbf at the distal end of the control wire  118 . As discussed above, losses along the elongated flexible shaft may require the user to apply a force substantially greater than this to the handle body  102 . 
     Once the ball  140  has separated from the rest of the control wire  118 , the user can pull the rest of the clipping device  100  from the endoscope. As this is done, the yoke  204  is retained within the capsule  200  by the spring and frictional forces of the capsule tabs  306 . Prior to withdrawing the clipping device  100 , the over-sheath  150  may be moved distally by the user over the entire remaining portions of the shaft section  104  to prevent damage to the endoscope as the clipping device  100  is withdrawn therethrough. The sheath stop  156  may also be placed on the shaft section  104  proximally of the over-sheath grip  152  to prevent inadvertent sliding of the over-sheath  150  from the distal end of the device  100 . 
     A more detailed description of several components of the clipping device  100  follows. The clip arms  208  are shown in detail in  FIGS. 18, 19 and 20 ; the tension member  206  is shown in side and top views in  FIGS. 25 and 26 ; while top and side views of the yoke  204  are shown respectively in  FIGS. 27 and 28 . the clip arms  208  may be formed of a biocompatible material such as Nitinol, Titanium or stainless steel. Maximum spring properties may be obtained by using materials such as 400 series stainless or 17-7 PH. As shown, a tear drop keyway  400  is formed in the clip arm  208  to mate with a corresponding tear drop key  402  formed on the tension member  206 . This feature maintains the relative positions of these two components and of the yoke  204  substantially constant. The shape of the keyways  400  may be varied. For example, the keyway  400  may be oval or elliptical. Central portions of the clip arms  208  define a spring section  404 . When the proximal ends  252  of the clip arms  208  are under the yoke overhangs  254 , the clip arms  208  are allowed to pivot over the tension member  206 , which in turn biases the distal ends  252  towards the open configuration when no longer restrained by the capsule  200 . As a result, the proximal end  252  of each clip arm  208  springs upward and engages the latch windows  304  in the capsule  200 . 
     The clip arms  208  also comprise a radius section  300  that adds strength to the clip and reduces system friction. The radius of the radius section  300  approximately matches the inner diameter of the capsule  200  and has a smooth profile to avoid scratching the inner surface of the capsule  200 . A pre-load angle α is defined between the radius section  300  and the spring section  404 . The pre-load angle α determines how much interference (pre-load) exists between the two opposing clip arms  208  at their distal ends when closed. The greater the pre-load angle α, the greater the engaging force that is applied by the clip arms  208 . However, this condition also causes the greatest system friction when the hemostatic clip  90  is closed. The clip arms  208  also comprise interlocking teeth  408  disposed at their distal ends. In the exemplary embodiment, the teeth  408  are identical so that the arms may be interchangeable and will mesh smoothly with the set facing them. The teeth  408  are disposed at a nose angle β which may be between approximately 90 and 135 degrees, but in other applications may be greater or lesser than the described range. 
     The capsule  200  is shown in detail in  FIGS. 14 and 15  and comprises alignment keyways  500  that are designed to mate with corresponding features on the bushing  202  to rotationally align the two components. The capsule tabs  306  may be bent towards the centerline of the capsule  200  to engage the bushing undercuts  350 . The engagement maintains the integrity between the capsule assembly  200  and the rest of the clipping device  100  until the yoke is pulled into the distal bushing shoulder. the capsule overhangs  502  provide added clamping strength to the deployed clip arms  208 . This is achieved by reducing the length of the portion of each clip arm  208  that is not supported by a portion of the capsule  200 . This feature does not affect the amount of tissue that may be captured by the clip arms  208  since the capsule overhangs  502  extend on a plane substantially parallel to the plane of the clip arms  208 . 
     Additional features of the capsule  200  include an assembly aid port which may be used to assist in aligning the components of the clip assembly  106 . Bending aids  506  facilitate a smooth bend when the distal folding tabs  220  are bent inward, as described above. The bending aids  506 , as shown, are holes aligned with the folding line of the tabs  220 , but may also include a crease, a linear indentation, or other type of stress concentrator. The capsule  200  may be formed from any of a variety of biocompatible materials. For example, stainless steel, Titanium or Nitinol or any combination thereof may be used. High strength polymers like PEEK™ or Ultem™ may also be used to form the capsule  200 , with a heat set treatment being used to adjust positionable elements. 
       FIGS. 25 and 26  depict additional details of the tension member  206 . As shown, tear drop keys  402  are designed to engage the tear drop keyways  400  of the clip aims  208 , as described above. Clip follower planes  508  are shaped to form a fulcrum which allows the clip arms  208  to rock between the open and closed configurations. The tension member  206  comprises a distal stop face  510  which abuts the distal folding tabs  220  of the capsule  200  to stop the distal motion of the capsule assembly  106 . In general, all surfaces and edges of the tension member  206  that are in contact with the inner surfaces of the capsule  200  preferably have a radius substantially similar to an inner radius of the capsule  200  to provide a sliding fit therein. The tension member  206  may be formed of a biocompatible polymer, monomer or thermoset. The type of mechanism selected to release the tension member  206  from the yoke  204  may determine the type of material used since a release due to fracture of the male C section  214  requires a relatively brittle material while release due to yielding without fracture calls for a softer material. 
     Additional details of the yoke  204  are shown in  FIGS. 27-29 . When the control wire  118  is seated in the yoke  204 , it is desirable to ensure that it cannot inadvertently be removed from the control wire slot  600 . Accordingly, in the present embodiment the ball cavity  602  has a diameter sufficiently large to allow the ball  140  to pass therethrough while the wire cavity  604  is large enough to allow the control wire  118  to pass therethrough, but not large enough to allow the ball  140  pass therethrough. To assemble the control wire  118  with the yoke  204  according to the exemplary embodiment, the proximal end of wire  140  is inserted into the ball cavity  602  until the ball bottoms out, and then the control wire  118  is rotated until it is seated in the control wire cavity  604 , thus constraining further movement of the ball  140 . According to the present embodiment, the yoke  204  may be made of a biocompatible metal such as stainless steel or a high strength polymer such as Ultem™. 
     According to embodiments of the present invention, the clipping device  100  may be scaled to fit the requirements of different surgical procedures. In one exemplary embodiment, the clipping device  100  may be sized to fit through an endoscope having a working channel diameter of approximately 0.110 inches. The exemplary bushing may have a length of about 0.22 inches and an OD of approximately 0.085 inches. The capsule may have a length of about 0.5 inches, an OD of about 0.085 inches, and a wall thickness of about 0.003 inches. When assembled, the rigid length of the capsule  200  and the bushing  202  is approximately 0.625 inches. This length is important because if it is too great, the assembly will not pass through the bends of the flexible endoscope. In the exemplary clipping device, the outer sheath may have an ID of approximately 0.088 inches and an OD of about 0.102 inches. The overall length of the clipping device may be approximately 160 inches, while the tissue grasping portion of the clip arms  208  may be approximately 0.4 inches long. 
     As shown in  FIGS. 30-31 , an alternate embodiment of a clipping device  700  comprises a clip assembly  706  connected to and movable via a handle assembly (not shown). The clipping device  700  is substantially similar to the clipping device  100  with a capsule  800  providing a structural shell for the clip assembly  706 . The capsule  800  houses a yoke  804  and a tension member  806  for moving clip aims  808  coupled thereto, between open and closed configurations via movement of first and second control wires  718 ,  720 . The yoke  804  is substantially similar to the yoke  204  of the clipping device  100 , but includes a first portion  830  and a second portion  832  connected to one another via the first control wire  718 . 
     The first control wire  718  is substantially similar to the control wire  118 , except that an enlarged diameter portion (e.g., ball  740 ) is formed at a proximal end  724  thereof while the distal end  722  is coupled to the first portion  830 . The ball  740  is releasably and rotatably received within the second portion  832 . In a preferred embodiment, the distal end  722  is integrally formed with the first portion  830  with the first control wire  718  extending proximally therefrom. The proximal end  724 , including the ball  740 , may be mated with the second portion  832  by, for example, crimping the second portion  832  over the proximal end  724 . As will be understood by those of skill in the art, the length of the first control wire  718  increases the extent of free space between proximal and distal ends of the yoke  804 , thereby allowing additional structural support components at a distal end of the clipping device  700 , while maintaining the rotatability of the device to prevent wind up of the second control wire  720 . 
     The second control wire  720  extends longitudinally from a distal end  726  connected to the second portion  832  to a proximal end (not shown) connected to, for example, a spool (not shown) of a handle assembly. Similarly to the clipping device  100 , the second control wire  720  may be moved distally and proximally to move the clip arms  808  between the open and the closed configurations. The second control wire  720  may be integrally formed with the second portion  832  such that the second control wire  720  extends proximally therefrom. 
     The first portion  830  may be formed substantially similarly to a distal portion of the yoke  204 . The first portion  830  includes a yoke overhang  854  receiving proximal ends  852  of the clip arms  808 . Similarly to the yoke  204 , the first portion  830  also includes a connection mechanism at a distal end  834  thereof for releasably connecting to the tension member  806 . The tension member  806  may be released from the yoke  804  upon exertion of a predetermined level of force in the same manner described above. The second portion  832  may be substantially similar to the proximal end of the yoke  204 , including a socket  810  for receiving the ball  740  of the first control wire  718 . The socket  710 , however, is open to a distal end  836  of the second portion  832  to facilitate connection between the first and second portions  830 ,  832  via the first control wire  718 . 
     It will be understood by those of skill in the art that the clipping device  700  may be used in substantially the same manner as described above in regard to the clipping device  100  with the same separate feedback indications to the user. Specifically, a first tactile feedback is provided to the user when the clip assembly  706  has been drawn proximally into the capsule  800  to a point beyond which further proximal movement of the clip assembly  706  into the capsule  800  will deploy the clip. A second tactile feedback is then provided when the first and second portions  830 ,  832  have been separated from one another locking the clip over the target tissue. A third tactile feedback provided to the user when the ball  740  of the first control wire  718  has been separated from the first portion  830  of the yoke  204  indicates that the clipping assembly  706  and the capsule  800  have been separated from the device  700 . 
     The handle assembly, which may include a handle body and spool longitudinally movable along the handle body, is used to move the clip arms  808  between the open and the closed configuration in the same manner indicated above. Specifically, the spool, which is connected to a proximal end of the second control wire  820  may be moved relative to the handle body to move the clip aims  808  between the open and closed configurations. Application to the second control wire  720  of a proximally directed force greater than a threshold level deploys the clip assembly  706  separating the clip assembly  706  from a remaining portion of the clipping device  700 , as described above in regard to the clipping device  100 . 
     According to another embodiment, as shown in  FIGS. 32-33 , a control wire and yoke assembly  900  are substantially similar to the assembly described above in regard to the control wire  118  and the yoke  204  of the device  100 , comprising a control wire  918  and a yoke  1004  couplable with one another. The control wire  918  includes a wire portion  919  and a ball  940  at a distal end thereof. The control wire  918  and the yoke  1004  are substantially similar to the control wire  118  and the yoke  204  described, above, but are coupled together in a different a manner. In particular, the yoke  1004  is formed of a first component  1004   a  and a second component  1004   b  joined together to encapsulate the ball  940  of the control wire  918  and permit free rotation of the control wire  918  relative to the yoke  1004  about a longitudinal axis of the control wire  918 . Free rotation of the control wire  918  relative to the yoke  1004  permits the clipping device to function as desired, without binding. Although the yoke  1004  is not shown as including any specific surface features, it will be understood by those of skill in the art that the yoke  1004  may include any of a variety of desired surface features as described above, such as, for example, a yoke overhang for receiving proximal ends of clip arms and/or a portion for joining the yoke  1004  to a tension member, as described above in regard to the embodiments above. It will be understood by those of skill in the art that the control wire and yoke assembly  900  may be used in place of the control wire and yoke assemblies described above in regard to the to the clip devices  100 ,  700 . 
     As shown in  FIG. 32 , the first and second components  1004   a ,  1004   b  include recess portions  1005   a ,  1005   b , respectively, which, when the first and second components  1004   a  and  1004   b  are joined to one another, form a cavity sized and shaped to rotatably retain the ball  940  of the control wire  918  therein. The first and second components  1004   a ,  1004   b  may, for example, be substantially symmetrical to one another about a longitudinal axis of the assembly  900  and may be joined to one another along a surface parallel to the longitudinal axis. When assembled, the recess portion  1005   a  of the first component  1004   a  faces the recess portion  1005   b  of the second component  1004   b  with the first and second recess portions  1005   a ,  1005   b  including first parts  1007   a ,  1007   b , respectively, for accommodating the ball  940  and second parts  1009   a ,  1009   b , respectively, for accommodating a portion of the wire  919  extending proximally from the ball  940 . The first parts  1007   a ,  1007   b  are concave and, for example, substantially hemispherical while the second parts  1009   a ,  1009   b  each form, for example a part of a cylinder with a diameter less than that of the first portions  1007   a  and  b . Thus, when the first and second components  1004   a ,  1004   b  of the yoke  1004  are joined together with the ball  940  received between the recess portions  1005   a ,  1005   b  thereof, as shown in  FIG. 33 , the first parts  1007   a ,  1007   b  form a cavity  1007  which is partially spherical for housing the ball  940  and the second parts  1009   a ,  1009   b  form a substantially cylindrical opening  1009  for accommodating the wire portion  919  extending from the ball  940 . A diameter of the cavity  1007  is selected to be larger than a diameter of the ball  940  such that the ball  940  is freely rotatable therein. The first and second components  1004   a ,  1004   b  of the yoke  1004  may be bonded to one another using any known bonding/attachment mechanism such as, for example, ultrasonic welding and adhesive bonding. The first and second components  1004   a ,  1004   b  may be formed of a material such as metal, plastic, or any other material known to those in the field. 
     In an alternate embodiment, as shown in  FIGS. 34-35 , an assembly  900 ′ may be substantially similar to the assembly  900  described above, comprising a yoke  1004 ′ and a control wire  918 ′. The yoke  1004 ′, however, is divided into first and second components  1004   a ′,  1004   b ′ substantially perpendicular to a longitudinal axis thereof. Thus, as shown in  FIG. 34 , a recess  1005   a ′ of the first component  1004   a ′ may be concave and substantially hemispherical while an interior surface  1005   b ′ of the second component  1004   b ′ includes a sloped portion  1007   b ′ sized and shaped to seat the ball  940 ′ therein and an opening  1009 ′ extending therethrough from the first sloped portion  1007   b ′ to an exterior surface  1011 ′ of the second component  1004   b ′ for accommodating a wire portion  919 ′ of the control wire  918 ′ extending proximally from the ball  940 ′. The opening  1009 ′ is thus sized and shaped to slidably receive the wire portion  919 ′ while preventing the ball  940 ′ from passing therethrough. When the first and second components  1004   a ′,  1004   b ′ are joined to one another, as shown in  FIG. 35 , the ball  940 ′ is encapsulated in a cavity  1007  formed by the recess portions  1005   a ′,  1005   b ′ and permitted to freely rotate therein. Thus, the first and second components  1004   a ′,  1004   b ′ are joined together, such that the control wire  918 ′ is freely rotatable about a longitudinal axis thereof. 
     According to a further embodiment, as shown in  FIGS. 36-38 , an assembly  1100  is substantially similar to the assembly  900 , comprising a ball  1140  at an end of a control wire  1118  that is encapsulated between first and second components  1204   a ,  1204   b  of a yoke  1204 . The assembly  1100 , however, further comprises an insert  1260  formed of a first and second element  1260   a ,  1260   b  each of which is configured for insertion into recess portions  1205   a ,  1205   b  of the first and second components  1204   a ,  1204   b , respectively, so that the ball  1140  is seated in the insert  1260  between the first and second components  1204   a ,  1204   b . The first and second components  1204   a ,  1204 , and thereby the first and second elements of the insert  1260   a ,  1260   b , are joined together around the ball  1140  of the control wire  1118  to permit free rotation thereof relative to the yoke  1204 . The insert  1260  is formed of a material stronger than a material of which the yoke  1204  is formed so that the insert  1260  may provides support for devices in which a break mechanism of the control wire  1118 —e.g., a reduced diameter section of a control wire designed to fail when a predetermined tension is applied thereto—requires a tension greater than that which the material of the yoke  1204  can withstand. 
     When the first and second elements  1260   a ,  1260   b  of the insert  1260  are joined to one another, as shown in  FIG. 38 , an exterior surface  1262  of the insert  1260  corresponds, for example, to a shape of a cavity  1007  formed by the recesses  1205   a ,  1205   b . The exterior surface  1260  further includes an annular flange  1270  extending radially outward therefrom to engage a corresponding groove  1272  in each of the recesses  1005   a ,  1005   b  of the first and second components  1204   a ,  1204   b  such that the first and second elements  1260   a ,  1260   b  of the insert  1260  may be press-fit into the first and second components  1204   a ,  1204   b , respectively. Although the assembly  1100  is specifically shown and described as including the annular flange  1270  and the corresponding groove  1272 , it will be understood by those of skill in the art that any of a variety of elements may be employed to facilitate attachment between the first and second elements  1260   a ,  1260   b  of the insert and the first and second components  1204   a ,  1204   b.    
     An interior surface  1264 , when the first and second elements  1260   a ,  1260   b  are joined to one another, includes a portion  1266  for seating the ball  1140  and an opening  1268  sized to permit the wire portion  1119  of the control wire  1118  to pass therethrough. The portion  1266  for seating the ball  1140  is, in this embodiment, substantially hemispherical, corresponding to a shape of at least a portion of the ball  1140 . The opening  1268  is sized and shaped to permit the wire portion  1119  to extend therethrough while preventing the ball  1140  from passing therethrough. Thus, when the first and second components  1204   a ,  1204   b , and thereby the first and second elements  1260   a ,  1260   b , are joined to one another, the ball  1140  is encapsulated between the first and second components  1204   a ,  1204   b  and seated within the portion  1266  of the insert  1260 , permitting the control wire  1118  to freely rotate about a longitudinal axis  1265  thereof relative to the yoke  1204  and the insert  1260 . 
     In an alternative embodiment, the insert  1260  may be formed of a single element rather than the first and second elements  1260   a ,  1260   b . In such an embodiment, the ball  1140  of the control wire is first seated within the concave portion  1266  with the wire portion  1119  extending through the opening  1268 . The control wire  1118  and insert  1260  combination may then be encapsulated between the first and second components  1204   a ,  1204   b.    
     The present invention has been described with reference to specific exemplary embodiments. Those skilled in the art will understand that changes may be made in details, particularly in matters of shape, size, material and arrangement of parts without departing from the teaching of the invention. For example, different shapes of the yoke, the tension member and the hushing may be used, and different attachments of the clip arms and control wire may be employed. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest scope of the invention as set forth in the claims that follow. The specifications and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.