Abstract:
A bipolar electrosurgical forceps comprises an elongated tubular barrel having a proximal end, a distal end and a lumen extending between these two ends. A handle is provided at the proximal end of the barrel and includes an actuating member for opening and closing a pair of forceps jaws that are mounted at the distal end of the barrel. The forceps jaws include cam slots in a proximal head portion thereof. A coupling member extends between the actuating member on the handle and the pair of forceps jaws. The coupling member includes drive pins that cooperate with the cam slots whereby squeezing of the actuating mechanism first effects pivotal rotation of the pair of forceps jaws over a first range of motion of the actuating member and translation without rotation of the forceps jaws over a second range of motion of the actuating member.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     I. Field of the Invention  
         [0002]     The present invention relates generally to electrosurgical instruments, and more particularly to a bipolar electrosurgical device for coagulation and cutting of target tissue and specifically designed for use in the performance of percutaneous laparoscopic surgery or other endoscopic procedures.  
         [0003]     II. Background of the Invention  
         [0004]     For a number of years, the medical device industry, in cooperation with healthcare providers, has been developing methods and devices to permit surgical procedures to be performed in a less invasive manner. Minimally invasive surgery generally involves the use of instruments that avoid the need to make major incisions in the body. Major incisions usually require a relatively long period of hospitalization and subsequent home recovery. Minimally invasive surgery has the salutary effects of shortening hospital stays and recovery times.  
         [0005]     Minimally invasive surgical procedures are generally performed through a trocar cannula. The cutting and coagulating instruments most often used are either electrosurgical or laser-based. While, generally speaking, laser based instruments are capable of more precise cutting than electrosurgical instruments, they are somewhat difficult to control, particularly in the close conditions of laparoscopic procedures.  
         [0006]     Electrosurgical instruments are either monopolar or bipolar in nature. In monopolar electro surgery, there is a greater potential for injury to body tissues because an electric current most pass through the tissues on a “path of least resistance” basis to a return electrode located on the patient&#39;s skin. In laparoscopic procedures, there is even a greater potential for complications when using monopolar instruments, due to the combined effects of the surgeon&#39;s limited field of vision, the proximity of other organs to the tissue being cut and the inherent tendency of monopolar RF energy to find a somewhat random path back to the return electrode.  
         [0007]     Bipolar electrosurgical instruments provide an improved margin of patient safety in certain minimally invasive surgical and interventional procedures. In the case of bipolar devices, the RF energy is contained at the surgical site because both the active electrode and the return electrode are located in close proximity to one another on the surgical instrument itself.  
         [0008]     Bipolar coagulating and cutting forceps are known in the art, examples of which may be found in U.S. Pat. Nos. 5,258,006, 5,445,638, and 5,562,546 to Rydell et al. The forceps jaws are used for grasping or gripping the tissue to be cut. A RF current may be made to pass through the tissue disposed between the clamped jaws to desiccate the tissue and then, in the case of the Rydell et al. &#39;638 patent, a mechanical cutting blade may be actuated and made to pass through the clamped tissue to sever it.  
         [0009]     U.S. Pat. No. 5,735,849 to Baden et al. describes an endoscopic, electrosurgical forceps having an elongated tubular barrel that has coagulating electrodes on the opposed jaw surfaces and a cutting blade similar to that which is disclosed in the Rydell &#39;638 patent but with an improved handle mechanism that allows the surgeon to select between a bi-directional mode or a uni-directional mode of jaw movement. In each instance, however, the electrode surfaces on the jaws approach one another in a relative parallel relationship during jaw closure and likewise, separate from one another in a relative parallel relation as the jaws are made to open. Maintaining this parallel relationship results in improved and more uniform coagulation but suffers a drawback that the amount of separation of the opposed jaw surfaces is somewhat limited, making it more difficult to place the open jaws about target tissue prior to jaw closure, desiccation and cutting.  
         [0010]     Consequently, a need exists for an electrosurgical forceps instrument that allows significantly wider jaw separation when the jaws are fully opened relative to one another but which will assume a more parallel movement as they are made to close upon target tissue captured therebetween.  
         [0011]     Given the constraints imposed on the surgeon while performing minimally invasive surgery through a trocar or the like, it would also be advantageous if the jaw assembly can be redirected via a control lever on the instrument&#39;s handle without having to reposition the trocar. The ability to redirect the angle at which the jaws extend from the instrument&#39;s tubular barrel facilitates the ability of the surgeon to gain purchase to target tissue during the course of a laparoscopic procedure. This is especially true when the instrument also has the capability of being able to rotate the barrel and jaw assembly without moving the handle, a feature disclosed in the Rydell et al. &#39;006 patent.  
       SUMMARY OF THE INVENTION  
       [0012]     The above-described drawbacks of prior art electrosurgical forceps are obviated by the cutting and coagulating electrosurgical forceps of the present invention. It comprises an elongated tubular barrel having a proximal end, a distal end and a lumen extending therebetween. A handle is provided at the proximal end of the barrel and includes an actuating member on the handle. A pair of forceps jaws is mounted at the distal end of the barrel where each of the forceps jaws has cam slots formed through a proximal head portion to which the tissue engaging surfaces of the jaws are joined. A coupling member extends between the actuating member on the handle and the pair of forceps jaws where the coupling member includes members that cooperate with the cam slots such that by squeezing the actuating mechanism effects pivotal rotation of the pair of forceps jaws over a first range of motion of the actuating member and translation without rotation of the pair of forceps jaws over a second range of motion of the actuating member.  
         [0013]     For example, and without limitation, the handle may have a pistol grip configuration with the “actuating member” being the trigger on the pistol grip. Initially, the individual jaw members may be at a predetermined angle with respect to one another and as the trigger is squeezed, the angle decreases to a point where the opposed jaw surfaces carrying the electrodes are parallel to one another and then continued squeezing of the trigger over a second range of motion brings the two jaws together in a parallel manner.  
         [0014]     As a further feature of the invention, a thumb lever is provided on the handle that is operatively coupled to the jaw assembly which is pivotally secured at the distal end of the elongated barrel whereby actuation of the thumb lever redirects the angle at which the jaw assembly projects from the distal end of the elongated barrel.  
         [0015]     The instrument further includes a reciprocally movable cutting blade disposed at the distal end of the tubular barrel and it can be made to project out the distal end of the barrel between the closed forceps jaws through actuation of a pushrod that is attached to the blade and that extends through the lumen of the barrel to a control lever on the handle. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0016]     These and other objects, advantages and features of the invention will become apparent to persons skilled in the art from the following detailed description of a preferred embodiment depicting the best mode contemplated for carrying out the invention. In the drawings, like numerals in the several views refer to corresponding parts.  
         [0017]      FIG. 1  is a side elevation view of the cutting/coagulating electrosurgical forceps comprising the preferred embodiment of the present invention;  
         [0018]      FIG. 2  is a longitudinal cross-sectional view revealing the internal working parts of the instrument;  
         [0019]      FIG. 3  is an enlarged detailed view of the distal end portion of the instrument, again in cross section;  
         [0020]      FIG. 4  is an exploded view of the jaw assembly illustrating its manner of attachment to the distal end of the instrument&#39;s barrel.  
         [0021]      FIG. 5  is a view illustrating the articulated mount of the jaw assembly to the instrument&#39;s barrel;  
         [0022]      FIGS. 6A-6E  illustrate the jaw member achieved by providing specially shaped cam grooves on the instrument&#39;s jaw members; and  
         [0023]      FIG. 7  is an exploded view of one jaw member and its associated electrode structure. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “upwardly”, “downwardly”, “rightwardly”, “leftwardly”, “distally” and “proximally” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.  
         [0025]     Referring to  FIG. 1 , there is indicated generally by numeral  10  a bipolar electrosurgical forceps comprising a preferred embodiment of the present invention.  
         [0026]     It is seen to include an elongated tubular barrel  12  having a proximal end  14 , a distal end  16  and a lumen  18  ( FIG. 3 ) extending therebetween. Disposed at the proximal end  14  of the tubular barrel is a handle assembly indicated generally by numeral  20 . The handle assembly  20  includes a rotatable knob  22  to which the barrel  12  is secured such that rotation of the knob  22  will rotate the barrel  12  about its longitudinal axis. Internal stops are provided which only permits rotation of knob  22  and the barrel through an angle that may be in a range from about 180° to close to 360°.  
         [0027]     Located at the distal end  16  of the tubular barrel  12  is a forceps jaw assembly  24  including a pair of cooperating jaw members  26  and  28  ( FIG. 2 ). As will be further explained herein below, the handle assembly  20  has a pistol like configuration with a handle member  30  adapted to be held in the palm of the surgeon&#39;s hand and with a trigger  32  extending outward through a slot in the handle. The trigger  32  is operatively coupled to the jaw assembly  24  such that squeezing the trigger  32  imparts movement of the jaw members  26  and  28  relative to one another. The mechanism for imparting the particular blade movement will be explained in greater detail when  FIGS. 2 and 3  are described.  
         [0028]     Projecting out from opposed side surfaces of the handle  30  are thumb levers  34  which when depressed so as to pivot counterclockwise when viewed in  FIG. 1  cause a blade  36  ( FIG. 2 ) to extend outward from the distal end of the instrument  10 , traveling through slots formed through the mating jaw surfaces of jaw members  26  and  28 . Ears, as at  37  in  FIG. 1 , project from the sides of the handle to limit the extent of counter-clockwise travel of the lever  34 .  
         [0029]     Also shown in  FIG. 1  is a further thumb lever  38  that is pivotally mounted in the handle  30  and which operatively connects to the jaw assembly  24  to cause the jaw assembly  24  to articulate about an axis represented by dashed line  40  in  FIG. 1 .  
         [0030]     Another feature illustrated in  FIG. 1  is the presence of a ratchet release trigger  42  that projects out through a slot formed in the undersurface of the handle  30 . Depression of this lever will release a ratchet-like mechanism yet to be described for maintaining a setting of the jaw members  26  and  28  relative to one another.  
         [0031]     An electrical adapter  43  connects to a cord  45  that extends through the handle and down the tubular barrel&#39;s lumen  18  to connect to electrode structures on facing surfaces of jaws  26  and  28  in a manner to be further described herein below.  
         [0032]     Having generally described the basic constructional features of the bipolar electrosurgical forceps, consideration will next be given to the mechanisms contained in the handle for controlling movements of the jaw assembly  24  from side to side, the movement of the jaws  26  and  28  from their open to their closed position, the movement of the instrument&#39;s cutting blade and the rotation of the blade assembly  24  through about 180° with respect to the longitudinal axis of the barrel  18 .  
         [0033]     With continued reference to  FIG. 2  which shows a longitudinal cross-sectional view taken down the midline of the instrument, the trigger member  32  pivotally connects to the handle half  30 ( a ) by means of a trigger hinge pin  44 . As in the aforereferenced Baden et al. U.S. Pat. No. 5,735,849, the trigger  32  is spring-biased by a spring wire  46  to project outward of the handle member  30 . As the trigger  32  is squeezed, it compresses the spring wire  46 . A bore  48  is formed through the trigger member  32  and fitted into this bore and held in place by a pin  50  is a trigger support  52  that is attached to a jaw drive rod  54 . The jaw drive rod is, in turn, braised or otherwise attached proximate its distal end to a flat flexible steel strap  56  that supports two spaced-apart, transversely-extending drive pins  58  and  60  that are more clearly seen in the enlarged exploded view of  FIG. 4 .  
         [0034]     The jaw drive rod  54  passes through a small aperture formed through a pawl  62  that is canted at a slight angle to the axis of the drive rod by a spring  63  and the tolerances are such that when the pawl is canted at an angle to the axis of the drive rod  54 , the drive rod can be moved in the proximal direction as the trigger  32  is squeezed, but is prevented from returning in the distal direction by the frictional engagement between the rod  54  and the pawl  62 . However, when the pawl  62  is oriented perpendicularly to the drive rod  54  rather than at an angle, there is no longer interference between the pawl and the drive rod and the spring  46  is able to move the drive rod  54  in the distal direction. Actuation of the ratchet release  42  serves to orient the pawl  62  perpendicularly to the drive rod.  
         [0035]     Also extending through the lumen  18  of the tubular barrel  12  is a blade push tube  65  that is affixed to the thumb lever  34  and that surrounds the jaw drive rod  54 .  
         [0036]     The thumb lever  34  is urged in the clockwise direction when viewed as in  FIG. 1  by means of a spring  64  such that thumb pressure must be brought to bear on the lever  34  in order to displace the blade  36  out the distal end of the tubular barrel and along the slots  67  ( FIG. 4 ) provided in the opposed faces of the jaw members  26  and  28 . These slots permit the blade member  36  to pass along the length of the jaw member as the lever  34  is manipulated to cut through desiccated tissue clamped between the opposed forceps jaws.  
         [0037]     With continued reference to  FIG. 2 , plastic shrink tubing  66  surrounds the outer barrel  12 . A knob  22  is rotatably supported on a cylindrical hub  68  on the distal end portion of the handle  30  with the knob being fixedly attached to the outer circumference of the shrink tubing covered barrel  12 . Thus, rotation of the knob  22  also rotates the barrel and the jaw assembly secured to the distal end thereof. A boss on the inside of the spindle travels in a slot in the distal end of the handle. The slot only runs 90° each direction from the top center. Thus, the barrels i limited to about 180° of rotation. This prevents undue twisting of wires  69  in cord  45 . This slot could be increased to give close to 360° of rotation, if desired.  
         [0038]     Turning next to the exploded view of  FIG. 4 , it can be seen that an articulation drive tube  70  is concentrically disposed within the lumen of the outer barrel  12  and is reciprocally movable therein. The proximal end of the articulation drive tube is attached to a slide member  72  disposed within the handle  30  and is operatively coupled to the lever  38  that is rotatably mounted with respect to the upper rear portion of the handle as shown in  FIGS. 1 and 2 . Movement of the handle to the left or right imparts axial movement of the articulation drive tube  70 .  
         [0039]     Formed on the distal end of the articulation drive tube  70  is a T-shaped tab  74  that is designed to fit within a T-shaped pocket  76  formed on a jaw support member  78 . While not visible in  FIG. 4 , the jaw support member  78  has a cylindrical protuberance on an undersurface thereof that is adapted to fit into a circular aperture  80  formed proximate the distal end of the outer tube  12 . Likewise, a second jaw support member  82  has a hub portion  84  from which a further cylindrical protuberance  86  projects. The protuberance  86  is adapted to fit within an aperture  88  in the distal end portion of the outer tube  12 . It is to be noted that the tab  74  on the articulation drive tube  70  is laterally offset from the axis defined by the aligned apertures  80  and  88  and, thus, when the articulation drive tube  70  is reciprocally moved, the jaw support members  78  and  82  will be made to pivot about that axis.  
         [0040]     Sandwiched between the jaw supports  78  and  82  are the forceps jaw members  26  and  28 . Each jaw member includes a head portion  90  and a jaw portion  92 . The head portion  90  of the jaw member  28  includes a first slot  94  that is diagonally oriented relative to a longitudinal axis of the jaw member  28 . A second cam slot  96  is also formed on the head portion  90  of the jaw member  28  and it is somewhat L-shaped with a stem segment  98  of the L generally aligned parallel to the cam slot  94  and a base segment  100  of the L that is at a predetermined angle to the stem segment  98 . Likewise, the head portion  90  of the jaw member  26  has a cam slot  102  oriented diagonally to a longitudinal axis of jaw member  26  as well as a complimentary L-shaped cam slot  104  with a stem segment  106  that runs parallel to the cam slot  102  and a base segment  108  that is at an angle to the stem segment.  
         [0041]     The hub  90  of the jaw member  28  further includes a slot  110  that is oriented generally perpendicular to the longitudinal axis of the jaw member. While not visible in  FIG. 4 , the head portion of jaw member  26  also has a slot-like that of slot  110  on jaw member  28 .  
         [0042]     When the jaw supports  78  and  82  are made to sandwich the head portions jaw members  26  and  28 , the drive pins  58  and  60  projecting laterally from the drive strap  56 , fit into the above-described cam slots on the jaw members. More particularly, drive pin  58  is made to reside in the cam slots  96  and  104  while drive pin  60  extends into the slots  94  and  102 . Short, stub-like pins, as at  112 , project outward from the inner face of the jaw support members so as to reside in the slots  110  in the respective jaw members.  
         [0043]     With the jaw supports and jaws so arranged and with the protuberances, like  86  on the jaw support members  82  and  78 , located within the apertures  80  and  88 , the jaw assemblies can be made to swing through a predetermined arc, as illustrated in  FIG. 5 , when the thumb lever  38  is pushed from one side to the other on the handle  30 .  
         [0044]     Turning now to  FIG. 6A  when the drive pins  58  and  60  are all the way forward in the distal direction of the instrument, as they will be when trigger  32  is not being squeezed, the opposing jaw surfaces  92  of the blade members  26  and  28  are at an angle to one another, providing the maximum opening between the distal tips of the two jaws. As the trigger  32  is begun to be squeezed and the drive pins  58  and  60  are pulled rearward, the caming action between the drive pins and the slots in which they reside causes the distance between the jaw tips, as well as the angle between the opposed jaw surfaces  92 , to decrease. With reference to  FIG. 6C , as the surgeon continues to squeeze the instrument&#39;s trigger  32  over a first range of motion, the drive pin  58  reaches the point where it exits the base of the L-shaped cam slots  96  and  104  and enters the stem segment thereof. At this point, the jaw surfaces  92  on the jaws  26  and  28  assume a parallel relationship to one another. Continued squeezing of the instrument&#39;s trigger over a second range of motion causes the jaw surfaces  92  to close together, moving in a parallel relationship to one another. See  FIGS. 6D and 6E .  
         [0045]     It is to be seen, then, that by providing the cam slots in the jaw member heads, the resulting electrosurgical forceps instrument allows significantly wider jaw tip separation when the jaws are fully open relative to one another, but that will assume a parallel movement as they are made to close upon target tissue captured between the tissue engaging portions of the jaws. This results in greater ease in gaining purchase of the target tissue while still providing improved electrocoagulation achieved when parallel jaw movement is involved.  
         [0046]      FIG. 7  is an exploded view of the jaw member  26  showing the manner in which an electrode is mounted on the jaw in opposing relation to a similar electrode mounted on the opposite jaw  28 . The jaw member  26  is fabricated from metal and to insulate the jaw member body from the electrode  94 , an insulating shim  96  is bonded to the jaw surface  92  and the electrode, in turn, is bonded to the insulating layer so as to be in a non-contact relationship with the metal jaw member  26 . The wire  69  that leads to the electrical plug or connector  43  attaches to the electrode  94 .  
         [0047]     This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.