Abstract:
Electrosurgical forceps are described that have jaws capable of being closed relative to one another, the jaws each supporting electrode structures especially shaped to enhance the ability of the instrument to desiccate/seal or cut tissue structures clamped between the opposed jaws. One of the opposed jaws has a generally arcuate cross-section with a raised central zone and the other electrode has a recess adapted to accommodate the raised central zone of the cooperating electrode. By appropriating the shaping the mating electrode surfaces, tissue structures placed between the jaws are stretched laterally as clamping occurs. The stretching action prevents bunching of the tissue and results in improved desiccation, sealing and cutting. A fine, uninsulated conductor disposed on the one jaw, but insulated from the electrode surface on that jaw, serves as a cutting electrode.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of complete application Ser. No. 10/188,207, filed Jul. 2, 2002 now abandoned and is incorporated herein by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   I. Field of the Invention 
   This invention relates generally to electrosurgical instruments, and more particularly to an improved forceps whose jaws are especially designed to facilitate selective cutting, desiccation and sealing of tissue structures without the need for an instrument exchange. 
   II. Discussion of the Prior Art 
   The prior art is replete with electrosurgical forceps for use in open and laparoscopic procedures to cut through tissue structures, desiccate the tissue and any blood vessels to stem bleeding and for creating a fluid-tight seal between tissue structures along the margins of a cut. The Stern et al. U.S. Pat. No. 5,443,463 describes a coagulating forceps for use in open procedures in which the cooperating faces of its opposed jaws are generally planar and support a plurality of electrodes on one jaw and temperature sensing elements on the opposed jaw. Cutting of tissue is by way of a sharp blade that is actuated following electrocoagulation on opposed sides of the cut line. 
   The Fineburg U.S. Pat. No. 5,458,598 describes an endoscopic cutting and coagulating device, which, like the Stern &#39;463 device has opposed jaw members whose opposed jaws are generally identical, each having a U-shape defining a central slot and with generally planar, albeit serrated, mating faces. A mechanical, sharpened blade, when actuated, passes longitudinally through the central slot following coagulation on each side of the cut. 
   The Wrublewski et al. U.S. Pat. No. 6,174,309 describes an electrosurgical instrument designed to seal and cut tissue. Embodiments for open and endoscopic procedures are described. In each case, the mating faces of the forceps jaws are such that one has raised electrode surfaces straddling a resiliently mounted cutting blade and the other has a recess for receiving the raised electrode surface therein when the jaws are closed and an intermediate groove in which the resiliently mounted cutting blade may enter. Coagulation takes place when tissue is squeezed between the jaws and a suitable voltage is applied between the raised electrodes on one jaw and on the opposite jaw. Cutting takes place when the voltage is applied between the cutting blade and the jaw having the recesses. 
   The Rydell et al. U.S. Pat. No. 5,445,638 describes a device somewhat similar to the Fineburg et al. &#39;598 patent described above. It, too, has jaws having planar mating surfaces. 
   In each of the above-described embodiments, tissue to be coagulated, desiccated is clamped between the jaws of the device and a voltage is applied to the jaws to cause an RF current to flow through the captured tissue to heat and vaporize the moisture in the tissue. Cutting then takes place as a separate step, either by applying a cut voltage to a movable, metal blade member relative to a cooperating jaw or by effecting movement of a sharp blade through the previously desiccated tissue. 
   SUMMARY OF THE INVENTION 
   We have found that significantly improved cutting, sealing or desiccation can be achieved, when compared to prior art devices of which we are aware, by providing a forceps with non-planar mating jaw surfaces. By providing one jaw with a first electrode surface having a raised male profile and the opposite jaw with a correspondingly shaped second electrode surface defining a female recess, as tissue is being clamped therebetween, it is placed under tension and stretched slightly, which allows it to be more readily and uniformly heated when a voltage is applied between the electrodes on the opposed jaws. The tension also aids in cutting in that the shaped electrodes improves movement of the cutting electrode through tissue. As a further feature of our invention, a cutting electrode is supported on the electrode surface on one of the jaw, but is electrically isolated from that electrode surface. Switching means are then provided for applying a desiccating or sealing voltage between the first and second electrode surfaces or a cutting voltage between the cutting electrode and the first and second electrode surfaces. 
   Other features and advantages of the invention will become apparent from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation view of an electrosurgical cutting and sealing forceps designed for use in open procedures; 
       FIG. 2  is a cross-sectional view taken along the line  2 — 2  in  FIG. 1 ; 
       FIG. 3  is a cross-sectional view taken along the line  3 — 3  in  FIG. 1 ; 
       FIG. 4  is a side elevational view of an electrosurgical forceps designed for use in laparoscopic procedures and having an electrode structure in accordance with the present invention; 
       FIG. 5  is a cross-sectional view taken along the line  5 — 5  in  FIG. 4 ; 
       FIG. 6  is a partial view of the forceps jaws having an alternative placement for a cutting electrode; 
       FIG. 7  is a partial side elevational view of a bipolar cutting, desiccating and sealing forceps jaw assembly fabricated in accordance with a further embodiment of the invention; 
       FIG. 8  is a cross-sectional view taken along the line  8 — 8  in  FIG. 7 ; 
       FIG. 9  is a cross-sectional view taken through the jaws of a still further embodiment in which an anvil of a compressible material is included; 
       FIG. 10  is a cross-sectional view like that of  FIG. 9 , but with the jaws slightly parted; 
       FIG. 11  is a cross-sectional view taken through the jaws of yet another embodiment of the invention; and 
       FIG. 12  is an electrical wiring diagram showing one way of switching a radio frequency electrosurgical generator to the electrodes of the forceps instruments of  FIGS. 1 and 4 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , there is indicated generally by numeral  10  a bipolar electrosurgical forceps that is adapted to clamp, seal, desiccate and cut tissue structures in the course of an open surgical procedure, the forceps  10  includes a first forceps half  12  comprising a handle member and a second body or forceps half  14  that are electrically isolated from each other and pivotally joined by a fastener  16 . The forceps halves  12  and  14  are preferably fabricated from a metal or plastic and have finger-receiving loops  18  and  20  at a proximal end thereof and jaws  22  and  24  at a distal end thereof. 
   Suitably fastened to a planar face  26  of the jaw  22  is a first conductive sealing electrode  28 . Electrode  28  may be integral to the jaw  22 . As can best be seen in the cross-sectional view of  FIG. 2 , the jaw/electrode  28  has obliquely extending sidewalls relative to a width axis of said jaw forming recess  30  whose arcuate sides converge to form a central, longitudinally extending notch  32  of rectangular cross-section. The exposed surfaces of the tapered arcuate recess and the notch are uninsulated. 
   The jaw  24  of the forceps half  14  has an electrode  34  either fastened to jaw surface  36  or integral with the jaw  24 . As can best be seen from the cross-sectional view of  FIG. 3 , the electrode  34  may have a generally arcuate or beveled cross-section with obliquely extending sidewalls forming a raised dome  36  in a central zone that is adapted to fit within and conform to the recess  30  of the electrode  28 . A cut electrode  42  is mounted to and extends along the length of the electrode  34 , and is isolated from electrode  34  by insulating plastic or ceramic  40 . As can be seen from  FIG. 3 , the strip  40  is generally centrally disposed at the crown of the arcuate dome  36 . 
   Referring once more to  FIG. 1 , a cutting electrode  42  may comprise a thin, rigid, isolated conductor disposed on the crown of dome  36  or, alternatively, may be a fine wire that is affixed at its distal end  44  to an end surface of the insulating strip  40 . The other end  46  of the wire cut electrode  42  is set in an insulating plastic  48  on the jaw  24 . Thus, while the cut electrode  42  runs closely parallel to the arcuate electrode  34  (typically within about 0.025 and 0.050 inch of electrode  34 ), it remains electrically insulated therefrom along its entire length. While a deposited conductor or a fine wire cut electrode has been found to function well, it is to be understood that the cut electrode can be otherwise configured so as to cooperate with the jaw members in the manner described. 
   Routed on or through the forceps half  18  is a three conductor cord  48  having terminals  50 ,  52  and  54  adapted to be plugged into jacks on an electrosurgical generator or a switch box associated therewith. A first of the three wires in the cord  48  connects to the electrode  28  mounted on the jaw  22 . A second conductor in the cord  48  exits the scissors half  12  proximate the pivot fastener  16  and connects to the electrode  34 . The third wire in the cord  48  connects to the cut electrode  42 . 
   In operation, tissue to be sealed and desiccated is positioned between the open jaws  24  and  26  of the forceps instrument  10  and when the forceps halves  12  and  14  are brought together, the tissue becomes squeezed between the arcuate, domed, male electrode  34  affixed to the jaw  24  and the inclined walls or electrode  38  defining the recess  30 . Squeezing the finger loops  18  and  20  toward one another results in the interposed tissue being squeezed and stretched by the wiping action between the mating electrode surfaces as the two are brought together. 
   By applying a predetermined voltage, via the cord  48 , between the electrodes  28  and  34 , tissue cells are desiccated and, in case the tissue structure is tubular, the walls thereof become sealed together. The notch  32  in the electrode  28  receives the cut electrode  42  therein, allowing the electrodes  28  and  34  to close tightly on the tissue structure to be electrocoagulated. 
   If it is desired to maintain the tissue structure clamped between the mating electrode surfaces for a time without the need for manually gripping the finger loops  18  and  20 , there is provided a tab  51  on the forceps half  14  having a plurality of parallel, saw-tooth, detent grooves  53  formed therein. A cooperating tab  55  with a barb  56  on its undersurface is formed on the forceps half  12 . As the forceps handles are brought together, the barb  56  can be made to fall into one of the plurality of saw-tooth notches  53  to thereby latch the forceps jaws in their closed disposition. 
   When it is desired to sever the tissue structure, a second predetermined voltage is applied, via the cord  48 , between the cut electrode  42  and the electrodes  28  and  34 . It will be recalled that the cut wire  42  and the electrode  34  are insulated from one another by virtue of the insulating strip  40  disposed in the groove  38  of the electrode  34 . By placing the lower jaw  24  beneath the tissue structure to be cut, and draping it over the surface of electrode  34  so that the tissue is brought into contact with the cut electrode  42  and jaw  34  as a predetermined voltage is applied, the tissue will be severed. Again, the shape of the jaws aids transection of tissue in that the tensioning better enables tissue to glide over the jaw/electrode. 
   A second embodiment of the invention is illustrated in  FIG. 4 . Here, the forceps instrument is designed for a laparoscopic procedure. The forceps of  FIG. 4  includes a handle member  60  that supports an elongated barrel  62  having forceps jaws at a distal end thereof, which are indicated generally by numeral  66 . The handle and mechanism for opening and closing the forceps jaws  66  relative to one another may be like that described in the Rydell U.S. Pat. No. 5,462,546, the contents of which are hereby incorporated by reference as if fully set forth herein. As is described in that patent, by manipulating the scissors-like handle  60 , a push rod  68  coupled to the jaws  66  by links  70  causes the jaws to open and close relative to one another. The first jaw  72  preferably comprises a rigid metal member having a concave recess  74  and a longitudinal notch  75 , as shown in the cross-sectional view of  FIG. 5 , which is taken along the line  5 — 5  in  FIG. 4 . The jaws may be straight and aligned with the barrel  62  or they may be curved as in the Rydell &#39;546 patent. 
   The other jaw  76  of the forceps comprises a metal electrode having a generally arcuate cross-sectional shape with a raised central dome that is adapted to fit within the concave recess  74  of the jaw member  72  when the jaws  72  and  76  are made to close relative to one another. The jaw  76  also supports a fine, narrow, conductive cut electrode  78  that remains electrically insulated from a metal jaw  76  in that its proximal and distal ends are embedded in an insulating strip  80  that is fitted into a groove  82  that extends longitudinally and is formed inwardly of the crest of the arcuate surface of the jaw  76 . 
   It can be seen that when the handle member  61  is squeezed, the jaws  66  close relative to one another while the cut electrode  78  remains electrically isolated from conductive surfaces of the jaw  76 . As with the embodiment of  FIG. 1 , because of the shape profile of the electrode surfaces of the jaw members  72  and  76 , when tissue is disposed between the jaws and the handle member  61  is squeezed, the tissue will be draped over the convex arcuate profile of the jaw electrode  76  and stretched taut by wiping action of the concave surface of jaw  72  as the two come together. Now, by applying a predetermined voltage to appropriate ones of the jacks  84 ,  86  or  88 , a current will be made to flow between the jaws  72  and  76  through the tissue captured therebetween to effect desiccation and/or sealing of the tissue structure. When it is desired to effect cutting of the tissue, a different voltage is applied between the cut electrode  78  and the jaw electrodes  76  and  72  to effectively cut through the tissue. It is not required that the jaws  72  and  76  be closed relative to one another during a cutting operation. By placing the lower jaw  76  beneath the tissue structure to be cut and draping it over the cutting electrode  78  so that the tissue engages both the cutting electrode and the metal jaw  76 , upon a slight lifting motion on the handle, application of a cutting voltage between the two will result in severing of the tissue. 
   Referring next to  FIG. 6 , there is shown a partial view of the forceps jaw portion of the laparoscopic instrument illustrated in  FIG. 4  but with the cutting electrode disposed on an exterior surface of a jaw rather than its mating surface. In this arrangement, the jaw assembly  66 ′ comprises a first jaw member  72 ′ and a second jaw member  76 ′ both being formed from a conductive material, such as stainless steel, Again, the blade assembly  66 ′ may be rectilinear or may have a curved profile. The mating faces of the jaws are preferably contoured in the fashion indicated in  FIG. 5  to provide a stretching or tensioning of tissue structures as it is being pinched between the mating jaw faces. In the embodiment of  FIG. 6 , however, the cutting electrode  78 ′ is repositioned so as to be located on an outer surface of the jaw member  76 ′ with a layer of insulating ceramic effectively electrically isolating the cut electrode  78 ′ from the metal surface comprising the jaw member  76 ′. In the embodiment of  FIG. 6 , the cut electrode  78 ′ is a small bump or protuberance rather than a length of wire as in the embodiment of  FIG. 5 . 
   In the arrangements of  FIGS. 4 and 6 , an electrical cord  83 , having three insulated conductors extends through the handle  60  and into the lumen of the tubular barrel  62  so as to electrically connect, individually, to the jaws  72  and  76  and to the cut electrode  78 . Connector pins  84 ,  86  and  88  permit the forceps instrument to be connected to a power source such as a conventional electrosurgical generator. 
     FIG. 7  shows an alternative jaw construction that is attachable to the handle mechanism of a laparoscopic forceps instrument like that of  FIG. 4 . Manipulation of the handle member  61  causes the jaws  89  and  90  to open and close in the manner earlier described to clamp and release tissue structures therebetween. The serrated teeth  91  on the opposed jaw surfaces allow better gripping of tissue therebetween. 
   Referring to the cross-sectional view of  FIG. 8 , the lower jaw  89  is raised and includes planar sidewalls that extend obliquely to the width axis of jaw  89  leading to a longitudinally extending slot  92 . Disposed in this slot is an insulator  93 , preferably of ceramic that supports a metal cutting electrode element  94 . A longitudinal cavity  95  runs along the inner surface of the recessed jaw  90  and it is lined with a thin layer of insulating material  96 . By providing this insulated surface, the top and bottom jaws exhibit generally equal tissue-contact areas important to providing effective tissue sealing. Planar sidewalls extend obliquely to the width axis of the jaw  90  to conform to the raised structure of jaw  89  and lead to the cavity  95 . 
   Electrical connection to the cutting element  94  and to the jaw electrodes is provided by a cord that extends through the handle and is adapted to be connected to an electrosurgical generator in the manner previously described. 
   When the forceps jaws are closed about tissue to be sealed, because of the profile of the mating jaw surfaces, the tissue will be stretched slightly. When an appropriate RF voltage is applied between the closed jaws  89  and  90 , an electrical current will pass through the tissue captured between the jaws to effect desiccation/sealing. If it is desired severe the tissue, a RF voltage is applied between the cutting electrode element  94  and the electrode comprising the jaw  89  and/or  90 . 
   Turning next to  FIGS. 9 and 10 , there is shown a modification that may be made to the blade structure of  FIGS. 7 and 8 . Here, the insulating layer  96  is replaced with a resilient strip  98  of an insulating material. A slight recess or channel  99  runs along the exposed edge of the strip. The resilient strip  98 , which may be one of a number of elastomers or a spring having an insulating coating, is bonded within a hollowed-out cavity formed in the recessed jaw  90  and runs parallel to the cutting electrode  94 . 
     FIG. 9  shows a cross-section through the jaw assembly when the jaws are squeezed together. It can be seen that the exposed cutting electrode  94  compresses the resilient insulating material  98  which, in turn, acts to push a tissue structure being severed against the cutting electrode. In the cross-section of  FIG. 10 , the raised jaw  89  and the recessed jaw  90  are slightly open relative to one another, showing the resilient material  98  in its undistorted condition. 
   In use, when the forceps jaws are clamped about a tissue structure to be cut, as the requisite voltages applied and cutting begins, the elastic properties of the resilient material supplies a force urging the tissue against the cutting electrode  94  to maintain a more uniform and consistent engagement of the tissue being severed with the cutting electrode. 
     FIG. 11  is included to illustrate that the cutting electrode element  94  and the ceramic cutting element holder  93  can be affixed to the recessed top jaw  90  instead of to the raised bottom jaw  89 , as in the embodiments of  FIGS. 7–10 . 
     FIG. 12  illustrates a switching arrangement for selectively coupling the outputs from an electrosurgical generator  100  to the three separate electrodes on the instruments of  FIGS. 1 ,  4  and  6 – 11  to selectively desiccate/seal tissue structures or to sever such tissue structures. When the double pole, double throw switch  102  is in the position illustrated in  FIG. 12 , the RF voltage from the generator will be applied between the electrodes  28  and  34  in the embodiment of  FIG. 1  or electrodes  72 / 72 ′ and  76 / 76 ′ in the embodiment of  FIGS. 4 and 6  or electrodes  89 – 90  in the embodiments of  FIGS. 7–11 . When the switch  102  is thrown to its alternate position, a voltage for cutting tissue will be applied between the cut electrode  42  ( FIG. 1 ) or  78  ( FIG. 4 ) or the protuberance  78 ′ ( FIG. 6 ) or to the cut electrode  94  in the embodiments of  FIGS. 7–11 , and the electrodes  34  ( FIG. 1 ),  76 / 76 ′ ( FIG. 4  or  6 ) or  89  ( FIGS. 7–11 ). It may prove expedient to connect a capacitor, C, between the conductors leading to the coag electrodes  28  and  34  in the embodiment of  FIG. 1  or electrodes  72  and  76  in the embodiment of  FIG. 4  or  89  and  90  in the embodiments of  FIGS. 7–11 . The capacitor, preferably having a capacitance of about 2.2 nF, functions to create an electrical link between the coag electrodes when the cutting electrode is energized. However, when the coagulating electrodes are energized, a sufficient voltage difference is generated between the coagulating electrodes to effect sealing/coagulation. The switch may take any number of forms and it, along with capacitor, C, may be conveniently located on the instrument itself, on the electrosurgical generator or on a foot switch module often used in electrosurgical systems. 
   With the jaw assembly  66 ′ on the laparoscopic instrument shown in  FIG. 4  in place of the jaw assembly  66 , sealing or desiccation takes place by closing the mating faces of the jaws  72 ′ and  76 ′ about the tissue and then applying a voltage between the two jaws causing a current flow through the captured tissue. When cutting, the voltage is preferably applied between the protuberance  78 ′ and the jaw members  76 ′. When the tissue to be severed is draped over the cut electrode  78 ′, it will also contact the jaw members  76 ′ functioning as a return electrode. Then by gently lifting the tissue while drawing the electrode  78 ′ thereacross, cutting occurs along a line traversed by the electrodes  78 ′. 
   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