Abstract:
The clip applier of the current invention solves the problems of prior art tools by incorporating a pre-clamp mechanism, the function of which is to pre-clamp the vessel to be ligated to a dimension such that the center leg of the spring of the ligation clip need be lifted only slightly. In this manner the spring clip can be slid over the smaller pre-clamped dimension. This insures that the clip spring material will remain within its elastic limit while allowing the tool to maintain a low profile for use in endoscopic surgery, even on large diameter vessels.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present application is a continuation of application Ser. No. 09/441,898, filed Nov. 17, 1999; which is a continuation of application Ser. No. 08/766,193, filed Dec. 12, 1996, now U.S. Pat. No. 5,993,465; which is a continuation of application Ser. No. 08/316,730, filed Oct. 3, 1994, now U.S. Pat. No. 5,858,018; which is a continuation-in-part of application Ser. No. 08/111,634, filed Aug. 25, 1993, now abandoned; the disclosure of which is incorporated by reference herein.  
           [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to mechanical devices used in surgical procedures to obtain ligation or hemostasis, and more particularly, to low profile tools that can apply a preformed, spring loaded ligation clip used during surgery to clamp around a vessel or duct, such as the cystic duct, and thereby obtain ligation.  
           [0004]    2. Description of the Prior Art  
           [0005]    It will be appreciated by those skilled in the art that the use of ligation clips to control bleeding during surgical procedures is well known. As described, for example, in U.S. Pat. Nos. 4,976,722 and 4,979,950, prior art clips are generally formed of metal wire, usually a titanium alloy, having a “U-shaped” rectangular cross-section. Such prior art clips often include a grooved pattern machined into the inner or clamping surfaces of the clip, in an attempt to enhance the ability of the clip to remain in position after it is closed around the vessel. Application of the clip to the vessel is normally effected by means of a crushing action produced by a clip applier, such as that disclosed in U.S. Pat. No. 5,030,226. Such crushing actions, of course, permanently deform the clips, making them difficult to remove or re-position.  
           [0006]    Prior art surgical ligation clips have several inherent problems. For example, the force applied by the clip to the vessel can be variable and inconsistent from one clip to the next, because of the variation in crushing force applied to the clip by the user. Further, prior art clips have a tendency to slip off the end of the blood vessel stub (i.e., parallel to the axis of the vessel) to which it has been applied, because of the low coefficient of friction associated with the clip, and lack of adequate restraining force provided by the clip. Because of this, separation of the clip from the vessel to which it has been applied, after the wound has been closed, is not uncommon. A related problem found in the prior art is the fact that the ligating or restraining force offered by the crushed clip varies along the length of the clip, decreasing toward the open end. Thus, the section of the vessel near the open end of the clip can be inadequately ligated.  
           [0007]    It is also common in the prior art to actually form and crush the clip only at the time of its application to the targeted blood vessel. It is often required that vessels of 4 mm and larger diameter be ligated. Because most clips of the prior art have no spring action it is required that the inside clearance dimension of the clip, prior to crushing, be larger than the vessel. This does not lend itself to clip applier designs that will pass through small 5 mm trocars. Accordingly, the clip applier mechanism of the prior art must be relatively large and cumbersome. This is a particular problem in laparoscopic procedures, during which both the clip and clip applier must be inserted through a trocar placed through the patient&#39;s external tissues and into the surgical field. Thus, prior art ligation clip appliers used in laparoscopic procedures universally consist of a 10 mm diameter clip applier that can fit only through a trocar having a 10 to 11 mm diameter entry port. Because one goal of laparoscopic surgery is to minimize the size of the entry wound, a surgical ligation clip and clip applier that can be used within a 5 mm diameter trocar port is highly desirable.  
           [0008]    To address these problems, a new and improved surgical clip was designed, as illustrated in FIGS. 1 and 2 and in U.S. patent application Ser. No. 08/111,634 filed on Aug. 25, 1993. The improved clip has a vessel clamping arm, a vessel support member, and at least one tension coil integrally joining the arm and support member. The clip is pre-formed so that in its equilibrium state, it can be easily placed within the surgical field, including through an endoscopic trocar port with as little as a five millimeter diameter. After the clip is placed proximate the blood vessel or duct to be clamped, the clamping arm is moved from its equilibrium position to a position under higher tension, allowing positioning of the vessel between the arm and support member. When correct placement and positioning is achieved, the arm is released and, as the arm tends to move back towards its equilibrium position, it clamps the vessel between the arm&#39;s curved lower surface and the supporting upper surface of the vessel support member.  
           [0009]    To enhance the performance of the tension coil(s), the vessel support member includes first and second arms, one of which terminates in a loop section. Minimal cross-sectional area of the clip is achieved by substantially longitudinally aligning the vessel support member, the clamping arm, the loop section, and the tension coil.  
           [0010]    The clamping arm is pre-formed into an equilibrium that generally aligns with the horizontal plan of the support member. A second embodiment of the clip pre-loads the clamping arm into a relaxed position where the free end of the arm rests against the upper surface of the support member.  
           [0011]    Unfortunately, several problems are encountered in applying this novel preformed, spring-action ligating clip onto a vessel through a 5 mm trocar port. First, the nominal 5 mm cross section of the clip that is inserted through the trocar places severe design restrictions on any applier mechanism. Traditional “crush type” clips require a crusher and anvil type applier mechanism which is too large to pass through a 5 mm trocar. Second, care must be taken so that the elastic limit of the spring material is not exceeded when the clip is opened up so that it can be placed over the vessel diameter. For titanium wire of diameter 0.75 mm, for example, lifting the distal end of the center leg of the spring much above 2 mm will exceed the elastic limit.  
           [0012]    What is needed, then, is a clip applier tool that may be used to place a preformed, spring action ligation clip around a large diameter vessel without permanently deforming or weakening the clip, one that will compress, without crushing, the vessel, and yet be small enough to use through a 5 mm trocar.  
         SUMMARY OF THE INVENTION  
         [0013]    The clip applier of the current invention solves the problems of prior art tools by incorporating a pre-clamp mechanism, the function of which is to pre-clamp the vessel to be ligated to a dimension such that the center leg of the spring of the ligation clip need be lifted only slightly. In this manner the spring clip can be slid over the smaller pre-clamped dimension. This insures that the clip spring material will remain within its elastic limit while allowing the tool to maintain a low profile for use in endoscopic surgery, even on large diameter vessels.  
           [0014]    These and other objects of the present invention will be apparent from review of the following specification and the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a perspective view in a somewhat schematic form of the device of the present invention.  
         [0016]    [0016]FIG. 2 a  illustrates in perspective the clips of the present invention within the cartridge of the device.  
         [0017]    [0017]FIG. 2 b  illustrates a perspective view of a clip for which the applicator of the present invention is designed.  
         [0018]    [0018]FIG. 2 c  is a cross section of the clip of FIG. 2 b  along the line C-C of FIG. 2 b.    
         [0019]    [0019]FIG. 2 d  is a side view of the clip shown in FIG. 2 b  with the clip opened.  
         [0020]    [0020]FIG. 3 shows a perspective view of the device of the present invention.  
         [0021]    [0021]FIGS. 4 a ,  4   b  and  4   c  show side, top and end views of the device of the present invention in the at rest position.  
         [0022]    [0022]FIGS. 5 a ,  5   b  and  5   c  show side, top and end views respectively of the device of the present invention with the clip assembly advanced to the ready position.  
         [0023]    [0023]FIGS. 6 a ,  6   b  and  6   c  show side, top and end views respectively of the device of the present invention with the pre-clamp arm opened.  
         [0024]    [0024]FIGS. 7 a  and  7   b  show side and top views respectively of the device with the pre-clamp arm pressing a vein and the clip opened for engagement with the vein.  
         [0025]    [0025]FIGS. 8 a ,  8   b  and  8   c  show the side, top and end views respectively of the device of the present invention with the pre-clamp arm closed and the ligation clip opened.  
         [0026]    [0026]FIGS. 9 a ,  9   b  and  9   c  show the side, top and end views of the device of the present invention in the position as occurs immediately following the position as shown in FIG. 8.  
         [0027]    [0027]FIGS. 10 a ,  10   b  and  10   c  show side, top and end views of the device of the present invention with the clip assembly extending beyond the end of the sleeve and the wings of the device releasing the clip.  
         [0028]    [0028]FIG. 11 shows a cross section of the device of the present invention along the length of the trunk.  
         [0029]    [0029]FIG. 12 shows a cross section of the device of the present invention taken to the left of the trunk.  
         [0030]    [0030]FIGS. 13 a  and  13   b  show a mechanism that can be incorporated in the device of the present invention to control advance of the clips into the ready position in the clip carriage. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    Referring now to FIG. 1, there is shown generally the preferred embodiment of the present clip applier. The device is indicated generally by the numeral  10 . The device  10  includes the pistol grip  12  and an applicator sleeve  14 . The applicator sleeve  14  contains a number of ligation clips  16  all in stacked relation and held in position in the manner hereinafter described. The ligation clips  16  are stacked generally in the trunk portion of the applicator sleeve  14  and extend from the end of the sleeve  14  that is connected to the pistol grip  12  toward the distal end  18  of the device  10 .  
         [0032]    [0032]FIG. 2 b  shows the shape and construction of a typical clip which the device  10  of the present invention is designed to apply during surgical procedures. The clip  16  is formed generally of a wire type material, preferably round in cross section and having base  20  and pressure arm  22 . The base  20  of this particular clip is an elongated U-shaped structure and pressure arm  22  overlies the base  20  and is positioned directly above the channel of the “U” formed between the two legs of the U-shaped base  20 . Base  20  and the pressure arm  22  are connected at their proximate end  24 . When the ligation clip  16  is in an at rest position, the pressure arm  22  directly overlies the channel between the two legs of the U-shaped base  20 . However, the pressure arm  22  can be rotated about the point of connection between the pressure arm  22  and the base end  20  at the proximate end  24  to open the clip. When the clip is opened, the pressure arm  22  is pivoted about the connection point between pressure arm  22  and base  20 . The connection between base  20  and pressure arm  22  is a spring type connection; however, that tends to bias the pressure arm  22  back into the “at rest” position as described previously. Thus, the ligation clip  16  may be opened by separating the pressure arm  22  from the base  20 . That separation occurs when the base is held in position and the pressure arm  22  is forced away from the base  20  (as in the illustration shown in FIG. 2 d ). Pressure is applied to pressure arm  22  to force it to rotate clockwise about the pivotal connection at proximate end  24  between base  20  and pressure arm  22 . However, when the pressure is released from pressure arm  22 , pressure arm  22  will rotate about the connection point between pressure arm  22  and base  20  at proximate end  24  in a counter clockwise position back into the at rest direction (as viewed in FIGS. 2 a  and  2   b ).  
         [0033]    When the ligation clip is applied to a blood vessel or artery, the pressure arm  22  is “opened” from the base  20 . The clip is inserted over the blood vessel so that the blood vessel traverses generally perpendicularly to the direction of the legs of the U-shaped base  20  over the top of the base  20  and beneath the pressure arm  22 . When the force that causes the pressure arm  22  to open from the base  20  is released, the pressure arm  22  captures the blood vessel between the underside of the pressure arm  22  and the top of the base  20  to compress the blood vessel and close it.  
         [0034]    Referring now to FIG. 3, at the distal end  18  of the device  10 , there is shown generally a pre-clamp arm  26 . Pre-clamp arm  26  can also be seen in FIGS. 6 a  and  7   a . FIGS. 4 a - 10   c  all show various views and positions of the mechanism at the distal end  18  of the device  10 .  
         [0035]    Referring now to FIGS. 4 a, b , and  c , the device  10  is shown in the at rest position. In the at rest position, a clip carrier/activator assembly  28  (shown generally within the area  28  shown in FIG. 4 a ) is retracted within the application sleeve  14 . For purposes of this description, the preferred embodiment will be referred to as it is oriented in the drawings. Clearly, if the device  10  was pointed in the opposite direction, the references to right and left would be reversed. The invention will be described with the understanding that the distal end of the invention and of the applicator sleeve are to the left, and the proximal end of the invention and the elements of it are to the right. Thus, the clip carrier/activator assembly  28  is in its extreme most right position when the device  10  is at rest.  
         [0036]    The applicator sleeve  14 , in the preferred embodiment, has the shape of an elongated tube with a step down  30  formed in its distal end. While the applicator sleeve  14 , in the preferred embodiment, is generally described as tubular and circular in cross section throughout the majority of its length, other cross-sectional shapes could be employed. The applicator sleeve has fingers  32  (FIG. 6 c ) curled over the step down portion  30  of its distal end. The pre-clamp arm  26  sits in the step down portion  30  of the applicator sleeve and fits within the envelope defined by the outer perimeter of the applicator sleeve  14  if that outer perimeter were extended beyond the left most tip of the device  10 .  
         [0037]    The pre-clamp arm  26  is elongated and, in the preferred embodiment, has an elongated slot  34  (FIG. 4 b ) defined by the two side arms  36 ,  36 ′. Depending nose  38  (FIG. 6 a ) is provided at the left end of the pre-clamp arm  26  and connector extension  40  (FIG. 4 b ) is formed with the pre-clamp arm  26  at its right end. Connector extension  40  has a hole  42  (FIG. 6 a ) through it and is formed with a camming surface  44  in the bottom right portion thereof.  
         [0038]    A carrier arm  46  (FIG. 6 a ) extends from the applicator sleeve  14  beyond the step down portion  30  toward the distal end of the device. The carrier arm  46  may be U-shaped in cross section or any other convenient configuration. In the preferred embodiment, the carrier arm  46  is U-shaped and has a base  48  and upwardly projecting legs  50 . A pin  52  extends through hole  42  and through holes in the legs  50  to connect the pre-clamp arm  26  to the carrier arm  46 . The carrier arm  46  has a step up  54  along the base  48  and located beneath the camming surface  44 . A spring  56  is connected to the carrier arm  46  and the bottom of the pre-clamp arm  26 , directly to the left of the pivot point of connection pin  52 . The spring  56  is biased such that it tends to pressure the pre-clamp arm  26  for clockwise movement (as viewed in FIG. 6 a ) about the pivot point  52 .  
         [0039]    Extending through the length of the applicator sleeve  14  along the upper side thereof is push rod  58 . A ramp  60  is formed in the left end of push rod  58 , and when the device is at rest, the push rod  58  is pushed to the left as can be seen in FIG. 4 a . When push rod  58  is extended to its left most extreme position, the camming surface  44  rides over the ramp  60 , forcing the pre-clamp arm  26  to rotate about the pivot point  52  in a counter clockwise direction into the closed position as shown in FIG. 4 a . The pressure of the camming surface  44  riding over the ramp  60  and forcing the counter clockwise rotation of the pre-clamp arm  26  about the pivot point  52  overcomes the pressure of spring  56  to hold the pre-clamp arm in a “closed” position. In the “closed” position, the depending nose  38  extends down and over the extreme left end of the applicator sleeve  14 .Pre-clamp arm  26  does not move length-wise relative to the length of the applicator sleeve  14 , its only movement is to pivot about the pin  52  being urged by spring  56  in a clockwise rotation to an open position when a push rod  58  is retracted toward the proximal end of the device and being rotated counter clockwise about pin  52  to the closed position when the push rod  58  is advanced toward the distal end of the device  10  and the camming surface  44  is forced to ride over the ramp  60 .  
         [0040]    In operation, the purpose of the pre-clam arm  26  is to fit over a blood vessel or artery  62  (See FIG. 6 a ) and to flatten the vein so that it will be dimensionally sized to fit within the mouth of ligation clip  16  when pressure arm  22  is rotated in a clockwise direction to open the clip.  
         [0041]    The ligation clip carrier/activator assembly  28  will now be described. In the at rest position, the ligation clip carrier/activator assembly  28  is retracted into the applicator sleeve  14  toward the proximal end of the device as is shown in FIG. 4 a . In the at rest position, device  10  is inserted through a trocar for use in a surgical procedure. Once the device  10  is inserted through a trocar into a body cavity, the clip carrier/activator assembly  28  is advanced to the ready position shown in FIG. 5 a . The assembly  28  is captured on the distal end of the device beneath the fingers  32 . The assembly  28  includes clip carriage  64  and wings  66 . The clip carriage  64  is an elongated element that fits within the applicator sleeve  14  and is telescopically moveable within the applicator sleeve  14 . The clip carriage  64  also extends beneath the wings  66  as can be seen in FIG. 10 a  and  10   b.    
         [0042]    The ligation clips  16  are stacked within the clip carriage  64  with the proximal end  24  of each clip aligned to the right as is seen in FIG. 2 a . The trunk  68  (FIG. 10 a ) of the clip carriage  64  is that portion of the clip carriage to the right of the assembly  28  as shown in FIG. 4 a . The cross section of the trunk  68  of the clip carriage  64  is shown in FIG. 11. As can be seen from FIG. 11, the cross section of the trunk  68  is shaped to mate with the cross section of the ligation clips  16  so that the ligation clips  16  will be held in stacked alignment through the length of the trunk  68 . A plate and spring (not shown) are incorporated in the extreme right end of the trunk  68  of the clip carriage  64  to apply pressure against the proximal end  24  of the clip in the extreme right location of the device  10 . The spring applies force against the plate to pressure the clips toward the distal end of the device. Thus, after each clip is applied to a vein, another clip is forced into a ready position for application to another vein.  
         [0043]    In the region of the clip carrier/activator assembly  28  (see FIG. 4 a ), the clip carriage has a modified cross section. The general shape of the cross section of the clip carriage  64  in the region of the clip carrier/activator assembly  28  is shown in FIG. 12. As can be seen there, clip carriage  64  has a substantially semi-circular outer perimeter (the outer perimeter is of a shape to mate with the shape of the inner surface of the channel through the applicator sleeve  14 ), and the shape of the interior portion of the clip carriage  64  at this point is designed to mate with the lower portion of the cross sectional shape of the ligation clip  16 . However, beneath the channel formed by the two legs of the U-shaped base  20  of the clip  16  is a channel to house the ligation clip opening assembly. At this cross-sectional point of the device, above the base portion of the clip carriage  64  are located the wings  66 . Wings  66  have an elongated dimple  72  of a shape to mate with the upper and outer perimeter of the ligation clip  16 . Because the wings  66  are held beneath the fingers  32 , the elongated dimple  72  allows the wings to hold the clip in place against the pressure necessary to open the clip in the fashion that will be disclosed herein.  
         [0044]    The ligation clip opening assembly housed in the bottom most portion of the clip carriage  64  includes a depressor  74  (FIG. 6 a ). The depressor  74  is generally pencil shaped, approximately the length of the channel between the two legs of the base  20  of the ligation clip  16  and of a cross sectional profile of a size that will allow at least a portion of the depressor  74  to extend through the channel between the two legs of the base  20  of the ligation clip  16 . The depressor  74  is pivotally connected at  76  at its distal end to the upwardly projecting side walls of the clip carriage  64  and is permitted limited rotation about its pivotal connection  76 . When the depressor  74  is in the at rest position, it lies flat along the base  78  of the clip carriage  64 . A stop protrusion  80  is located on the depressor  74  to the left of the pivotal connection  76  to limit the rotation of the depressor  74 . The depressor  74 , from its at rest position, can only rotate in a counter clockwise direction (as viewed in FIG. 6 a ) and is limited in its movement because the stop protrusion  80  will engage the base  78  of the carriage assembly  64  after a limited counter clockwise rotation.  
         [0045]    The depressor  74  has a cam surface  82  at its proximal end. The cam surface  82  is in contact with the distal end of the clip actuation push rod  84 . The clip actuation push rod  84  is an elongated rod that fits within a channel in the base of the clip carriage  64  and is allowed to move to and fro within that channel from the at rest position shown in FIG. 6 a  to the trigger position shown in FIG. 7 a  and back to the at rest position of FIG. 6 a . When the clip actuation push rod  84  is advanced to the left into the trigger position shown in FIG. 7 a , the cam surface  82  of the depressor  74  rides up over the end of the clip actuation push rod  84  to rotate the depressor in a counter clockwise position. The proximal end of the depressor protrudes into the channel between the two legs of the base  20  of the ligation clip  16  against the under side of the pressure arm  22  of the clip and forces the clip into the open position shown in FIG. 2 d  and in FIG. 7 a . As the ligation clip  16  is being opened by the action of the depressor  74  against the pressure arm  22  of the clip, the entire clip carriage assembly is advanced toward the distal end of the device  10  in relationship to the applicator sleeve  14  so that the clip will capture the vessel  62  that has been flattened by the action of the pre-clamp arm  26 . The vessel will then be captured between the upper surface of the base  20  of the ligation clip  16  and the lower surface of the pressure arm  22  of the ligation clip  16  and the clip actuation push rod  84  can be retracted toward the proximal end of the device, allowing the depressor  74  to rotate back into the at rest position and release the pressure arm  22  to capture and close the vessel  62 .  
         [0046]    The next step in the procedure is to advance the clip carriage assembly  64  relative to the applicator sleeve  14  beyond the distal end of the applicator sleeve  14  (See FIGS. 10 a  and  b ). The wings  66  are connected to the clip carriage  64  by ribbon springs  86 . The ribbon springs  86  are loaded to pressure the wings  66  to fan away from each other in the manner shown in FIG. 10 b . The wings  66  will remain in parallel relationship so long as they are held within the applicator sleeve  14 ; however, once the wings  66  extend beyond the proximal end of the applicator sleeve  14 , they are free to follow the pressure of the ribbon springs  86  and fan away from each other. The opening of the wings  66  releases the clip from the restraint of the elongated dimple  72  and thus the clip  16  is released from the device. The distal tip of the device can be tipped slightly to allow the ligation clip  16  to clear the device  10  as the clip  16  holds onto the vessel  62  in the clamped position. At this point, the clip carriage assembly is retracted toward the proximal end of the device relative to the applicator sleeve  14 , the wings are returned within the confines of the applicator sleeve  14 , another clip is released to advance to the ready position and the procedure can be performed again.  
         [0047]    The mechanism for activating the pre-clamp arm and the clip assembly will now be described. Referring to FIG. 3, a cut away portion of the applicator sleeve shows the push rod  58  and the clip actuation push rod  84 . The pistol grip  12  is shown with the cover removed so that the operation of the device can be described. The housing  88  of the pistol grip  12  can be constructed of any convenient sturdy material. Within the housing  88  of the pistol grip  12  is a pre-clamp push rod lever  90  which is hinged at  92  via a pin connected to housing  88 . The pre-clamp push rod lever  90  has opposing ends, one end  94  pivotally connected to the proximal end of push rod  58  and the opposite end connected at pivot point  96  to the trigger  98 . The trigger  98  fits within slots  100 ,  100 ′ which allows the trigger  98  to traverse back and forth within the slots  100 ,  100 ′ in response to pressure on the trigger by the user of the device  10 . The return spring  102  is an expansion spring connected at one end against a stop  104  and at the other end against the inside of the trigger  98 . Thus, a user of the device applies pressure to the trigger  98  to force the trigger  98  to move to the right within the slots  100 ,  100 ′. The trigger  98  will return to its at rest position (its position to the extreme left within the device shown in FIG. 3) when the pressure applied by the user is released. When the trigger  98  is activated by pressure from the user to move the trigger  98  to the right, the lever  90  rotates about the pin point  92 . The end at connection point  96  of lever  90  will move toward the proximal end of the device  10  and the end at pivot point  94  will move in the direction of the distal end of the device  10 , thus causing the push rod  58  to move toward the distal end of the device  10  and causing the ramp  60  to ride beneath the camming surface  44  and force the pre-clamp arm  26  into a closed position.  
         [0048]    In the use of the device, the trigger  98  will be activated by the user to close the pre-clamp arm  26  while the device is being inserted through a trocar. Once a vein  62  that is to be ligated is located, the trigger  98  will be released, the pressure of spring  92  will force the trigger to move to the at rest position thereby rotating the lever  90  in a clockwise direction, retracting the push rod  58  toward the proximal end of the device and allowing the pre-clamp arm  26  to open. The device  10  will then be manipulated so that a vessel  62  is captured between the upper surface of the fingers  32  and the lower surface of the arm  26  and toward the proximal end of the depending nose  38  of the device. Once the vessel  62  is in position, the trigger  98  is activated by the user to cause a counter clockwise rotation of the lever  90  forcing the push rod  58  toward the distal end of the device and causing the pre-clamp arm to rotate counter clockwise about the pin  52  and compress the vessel  62  in the manner shown in FIG. 7 a . While holding the trigger  98  in the activated position, thus holding the pre-clamp arm  26  against the vessel  62  in the manner shown in FIG. 7 a , the user of the device next activates the clip carrier/activator assembly  28  through the use of the activator key  106 .  
         [0049]    Key  106  is contained within the housing  88  of the pistol grip  12  in slots similar to the slots  100 ,  100 ′ which retain the trigger  98 . Key  106  is allowed to move between an at rest position as is shown in FIG. 3 and an activated position which is to the right of the at rest position. Spring  108  is connected at one end to stop  110  and at the other end to the inside of the key  106 . Spring  108  is an expansion spring which tends to force the key  106  to the at rest position shown in FIG. 3.  
         [0050]    Clip carriage actuation lever  112  is pivotally connected to the housing  88  at pivot point  114 . Lever  112  extends down from pivot point  114  to a pivot connection  116  between the depending leg of the lever  114  and the key  106 . Thus, when the key  106  is activated, moving it in the direction of the proximal end of the device, the lever  112  is rotated in a counter clockwise direction about the pivot point  114 . Moving the lever  112  in a counter clockwise direction about the point  114  causes the upper leg of the lever  112  to move generally toward the distal end of the device. The upper portion of the lever  112  is connected to the clip carriage  64  via the link  118 . The link  118  is pivotally connected at one end  120  to the lever  112  and at the opposite end  122  to a boss  124  formed on the clip carriage  64 . By the linkage just described, when the key  106  is activated, the clip carriage  64  moves toward the distal end of the device relative to the applicator sleeve  14  which at all times remains in a fixed position in relationship to the housing  88  of the pistol grip  12 . By activating the key  106 , through the operation of the clip actuation cam follower  126 , the clip actuation push rod  84  is advanced relative to the clip carriage  64  concurrently with the movement of the clip carriage  64  relative to the sleeve  14 . The clip actuation cam follower is pivotally connected at  128  to the upper portion of the lever  112  so that when the upper portion of the lever  112  moves in the direction of the distal end of the device, the cam follower  126  rides over the clip actuation cam  130  causing the clip actuation cam follower  126  to rotate in a clockwise direction relative to the lever  112 . The clip actuation push rod  84  is connected at its proximal end to the depending leg of the clip actuation cam follower  126  at  132 . Thus, the clip actuation push rod  84  moves toward the distal end of the device relative to the clip carriage assembly  64  and causes the depressor  74  to ride over the distal end of the clip activation push rod, forcing the depressor upwardly against the pressure arm  22  of the ligation clip  16 .  
         [0051]    By the mechanism described, the activation of key  106  advances the clip carriage assembly to the position shown in FIG. 7 a . Continued pressure on the key  106  advances the clip actuation cam follower  126  over the clip actuation cam  130  so that the follower  126  disengages from the cam  130 . A coil spring (not shown) is provided at the pivot point  128  tending to force the cam follower  126  to rotate in a counter clockwise direction. Thus, as soon as the cam follower  126  releases from the cam  130  after it passes over the cam  130 , the spring about the pivot point  128  will force the cam follower  126  to rotate in a counter clockwise direction thereby causing the clip actuation push rod  84  to retract toward the proximal end of the device. When the clip actuation push rod  84  retracts toward the proximal end of the device, the pressure of the depressor  74  is relieved from the underside of the pressure arm  22  and the pressure arm  22  closes on the vessel  64 , capturing the vessel  64  between the underside of the pressure arm  22  and the top side of the base  20  of the clip  16 .  
         [0052]    To release the clip  16  from the device, additional pressure is applied to the key  106  thus forcing the clip assembly  64  to advance further in the direction of the distal end of the device relative to the stationary sleeve  14 , forcing the wings  66  beyond the distal end of the sleeve  14  so that wings  66  may fan open and release the clip  16 .  
         [0053]    In order to return the device to the at rest or ready position for insertion of another clip, pressure on the key  106  is released. Spring  108  forces the key  106  toward the proximal end of the device thus rotating the lever  112  about the point  114  in a clockwise direction. The entire device is then reset. The cam follower  126  is allowed to pass back to the ready position by virtue of the pivotal connection of the cam  130  to the housing  88 . The cam  130  is pivotally connected at  134  to the housing  88  and the cam  130  has a ramp  136  formed on the surface of the cam  130  that faces the housing  88  of the grip  12  shown in FIG. 3. The cam  130  has a spring (not shown) tending to force the cam  130  against the housing  88  as shown in FIG. 3. When the cam follower  126  is returned to the at rest position, it will ride against the ramp  136  causing the cam  130  to rotate about the pivot point  134  and slip up slightly to allow the cam follower  126  to pass between the cam  130  and the housing  88 . Once the cam follower  126  clears the cam  130 , the spring will rotate the cam  130  back to the ready position as is shown in FIG. 3.  
         [0054]    Relieving the pressure on the key  106  also causes the clip cartridge  64  to retract toward the proximal end of the device into the ready position.  
         [0055]    A locking lever  137  is also provided on the lever  112  and pivotally connected to the lever  112  at point  138 . The locking lever  137  fits over the lever  90  so that when the key  106  is in the at rest position and the lever  112  is rotated into its clockwise most position, the locking lever  137  will hold the lever  90  in the position that would occur if the trigger  98  were depressed. Thus, the push rod  58  is advanced forward to cause the pre-clamp arm  26  to be closed. This locking lever allows the device to be inserted through a trocar without the user having to hold the trigger  98  in an activated position. In operation, once pressure is applied to the key  106 , the pressure of the locking lever  137  on the lever  90  is released allowing the spring  102  to push the trigger  98  toward the distal end of the device thereby retracting the push rod  58  and allowing the pre-clamp arm  26  of the device to open. Once the pre-clamp arm of the device is open, the pre-clamping pressure on a vessel  62  is created by activation of the trigger  98 , thus forcing the push rod  58  toward the distal end of the device and causing the pre-clamp arm to close against the fingers  32 .  
         [0056]    Once a clip has been applied in the manner described, a second clip is loaded into the ready position from the clip carriage  64  by the mechanism illustrated in FIGS. 13 a  and  13   b  forcing the ligation clip  16  to advance toward the distal end of the device.  
         [0057]    The mechanism shown in FIGS. 13 a  and  13   b  is mounted in the pistol grip  12  directly adjacent link  118 . The mechanism shown in FIGS. 13 a  and  13   b  is not illustrated in FIG. 3 for purpose of clarity. However, the additional mechanical structures shown in FIGS. 13 a  and  13   b  are mounted directly above link  118  and in engagement therewith.  
         [0058]    Referring now specifically to FIGS. 13 a  and  13   b , there is illustrated a clip pushrod  154  which is slidably mounted within the pistol grip  12  and permitted to move in a lineal direction along its length. The distal end  156  of the clip pushrod  154  will be in engagement with the rear most ligation clip  16  in the magazine of clips positioned in the carriage passageway. Movement of the clip pushrod  154  toward the distal end of the device will force the forward most ligation clip  16  into the carriage assembly.  
         [0059]    The controlling mechanism for advancing the ligation clips is provided by link  118  which has teeth  119  on the upper edge thereof in mating engagement with teeth  151  on the outer perimeter of the one-way ratchet clutch  150 . The cog wheel  152  is mounted to rotate with the one-way ratchet clutch  150  and is coaxially aligned with the one-way ratchet clutch  150 . The cogs  153  on the cog wheel  152  engage the cog ports  155  in the clip pushrod  154 . In operation, as can be seen from FIG. 13 b , upon forward motion of link  118  as is shown by the arrow in FIG. 13 b , the one-way ratchet clutch  150  will rotate counter clockwise, but cog wheel hub  158  will not rotate because the teeth  159  protruding from the cog wheel hub  158  will ratchet over the ramped ratchet teeth  160 . However, when the link  118  moves in the reverse direction, the engagement between the teeth  119  on the link  118  and the teeth  151  will cause the one-way ratchet clutch  150  to rotate in a clockwise direction, causing the tooth face  161  to engage the teeth  159  and rotate the hub  158  in a clockwise direction. FIG. 13 b  is viewed from the bottom of the assembly shown in FIG. 13 a ; thus, when viewed from the top, the only rotational movement of the cog wheel  152  will be in a counter clockwise direction upon the movement of the link  118  toward the proximal end of the device. When the link  118  moves toward the distal end of the device, the ratcheting mechanism will cause the cog wheel  152  to remain stationary.  
         [0060]    The operation of the assembly shown in FIGS. 13 a  and  13   b  will thereby control the movement of a clip  16  from the ready position into the carriage assembly as follows: when the device is being reset, link  118  moves to the rear, causing cog wheel  152  to rotate, advancing clip pushrod  154  to load a new clip into the clip carriage. When the mechanism is activated and the link  118  moves forward, the cog wheel  152  remains stationary so that the clips  16  in the clip magazine do not advance. Thus, the mechanism as described retains the clips in the ready position until the mechanism is activated by the retracting carriage assembly  64  rotating the cog wheel  152  and advance the clip pushrod  154  so that a single clip moves forward and is permitted to advance into the carriage assembly.  
         [0061]    As can be seen from FIG. 3, the device of the present invention can be used in a number of different procedures and the applicator sleeve  14  and related assemblies can be removed from the pistol grip and replaced with a clean sterile sleeve  14  for a second operative procedure with a new patient. The device is provided with a hinged cover  140  which is hinged to the housing  88  at  142 . The closure mechanism  140  can be held in place by any convenient safety latch  144  (see FIG. 1). The housing is provided with upper and lower recesses  146  and  148  and the sleeve  14  can be provided with bosses (not shown) that fit within the upper and lower recesses  146 ,  148  to stabilize the position of the applicator sleeve  14  in relationship to the pistol grip  12 . The pivotal connections  94 ,  122  and  132  can be designed so that the pins will slidably engage within the openings to permit the applicator sleeve  14  and related parts to be lifted from the pistol grip  12  and replaced by an applicator sleeve loaded with fresh ligation clips  16 . To make this replacement, it is necessary that the face of the pistol grip  12  be removable from the pistol grip and have means for connecting the face onto the pistol grip  12  in a fixed relationship. Any convenient latching mechanism can be provided to connect the face of the pistol grip onto the body of the pistol grip  12 .  
         [0062]    Thus, although there have been described particular embodiments of the present invention of a new and useful “Low Profile Tool for Applying Spring Action Ligation Clips”, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims. Further, although there have been described certain dimensions used in the preferred embodiment, it is not intended that such dimensions be construed as limitations upon the scope of this invention except as set forth in the following claims.