Abstract:
Bipolar electrosurgical instrument having a first and a second opposing jaw member at a distal end thereof, wherein each jaw member includes an outer housing, and an inner tissue engaging surface corresponding to the inner tissue engaging surface of the opposing jaw. The instruments includes the ability to move the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue. The jaws include asymmetrical electrodes disposed on the inner tissue engaging surfaces. A first contact region of the electrode has a greater surface area than that of the second contact region. During resection procedures wider electrodes impart improved sealing energy to the patient-side vessel while providing sufficient energy to resected tissue to effect hemostasis.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to electrosurgical instruments and methods for performing surgical procedures and, more particularly, to a bipolar electrosurgical forceps having an asymmetrical electrode configuration. 
         [0003]    2. Background of Related Art 
         [0004]    A hemostat or forceps is a simple pliers-like tool which uses mechanical action between its jaws to constrict vessels and is commonly used in open surgical procedures to grasp, dissect and/or clamp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal tissue. Such electrosurgical forceps may be used during conventional (open) surgery and during minimally-invasive (e.g., endoscopic) surgery. During minimally-invasive surgery, endoscopic instruments are inserted into the patient through a cannula, or port, which has been made with a trocar. The benefits of minimally-invasive surgery are well known, and include decreased operative times, faster recovery, and improved outcomes. 
         [0005]    Electrosurgical forceps commonly include an electrode on each opposing jaw surface. By controlling the intensity, frequency and duration of the electrosurgical energy applied through the jaw members, and by regulating the clamping force applied by the jaws to tissue, a surgeon can cauterize, coagulate, desiccate and/or simply reduce or slow bleeding of vessels and tissue. In particular, accurate application of pressure is important to oppose the walls of the vessel; to reduce the tissue impedance to a low enough value that allows enough electrosurgical energy through the tissue; to overcome the forces of expansion during tissue heating; and to contribute to the end tissue thickness which is an indication of a good seal. 
         [0006]    Many endoscopic surgical procedures require cutting blood vessels or vascular tissue. During certain endoscopic procedures, in particular, during resection procedures, vessels connecting the portion of the organ being resected must be cut to enable a surgeon to physically remove the organ from the patient&#39;s body. One portion of the severed vessel remains attached to the patient&#39;s vascular system, and the other portion of the severed vessel is removed with the resected organ. 
         [0007]    Conventional vessel sealing instruments are often used during these types of resection procedures, and apply electrosurgical sealing energy equally to the patient side of the vessel and to the resected portion of the vessel. This approach may have drawbacks, because while the patient-side vessel seal must withstand in vivo fluid pressures, the resected-vessel seal need only prevent incidental leakage from the resected organ. 
       SUMMARY 
       [0008]    The present disclosure relates to a bipolar forceps which includes a shaft having a first and second opposing jaw member at a distal end thereof and a drive assembly for moving the jaw members relative to one another from a first position, wherein the jaw members are disposed in spaced relation relative to one another, to a second position, wherein the jaw members cooperate to grasp tissue therebetween. The forceps are connected to a source of electrosurgical energy such that the jaw members are capable of conducting energy through tissue held therebetween to effect a tissue seal. A rotating assembly may also be included for rotating the jaw members about a longitudinal axis defined through the shaft. In embodiments, the forceps includes a selectively advanceable knife assembly for cutting tissue along the tissue seal. 
         [0009]    The forceps include opposing electrodes disposed on inner facing surfaces of the jaw members. The first jaw member includes a first electrode and a second electrode. The first electrode has a surface area greater than that of the second electrode. The first and second electrodes may have any suitable shape, however, in an embodiment the first and second electrodes have an elongate shape, wherein the first and second electrodes have a similar length, and the first electrode has a width greater than that of the second electrode. The second jaw member includes counterpart (e.g., mirror-image) first and second electrodes such that the first, larger electrode of the first jaw member corresponds with the first, wider electrode of the second jaw member. Similarly, the second, narrower electrode of the first jaw member corresponds with the second, narrower electrode of the second jaw member. The first and second electrodes on each jaw may be electrically coupled or electrically independent. 
         [0010]    The disclosed forceps may include an indicator to enable a surgeon to readily determine the position of the first and second electrodes. The indicator may be disposed on an outer surface of one or both jaws, on the shaft, and/or on the rotating assembly. The indicator may provide a visual indication (e.g., an icon, an arrow, a color, or other suitable visually-perceivable mark), a tactile indication (e.g., a raised area, a recessed area, a textured area, one or more “Braille-like” dimples, or other suitable feature perceivable by touch.) 
         [0011]    During use, a surgeon may position the jaw assembly such that the side of the jaws corresponding to the wider electrode is positioned towards the patient-side vessel and the side of the jaws corresponding to the narrower electrode is positioned away from the patient-side vessel. In this manner, the wider electrodes may impart improved sealing energy to the patient-side vessel, and reduce the amount of wasted sealing energy to the portion of the vessel being resected. 
         [0012]    The present disclosure describes an electrosurgical bipolar forceps having an electrode configuration for use in bipolar electrosurgical sealing and division, where the electrodes on one side of the jaws are larger than the electrodes on the opposite side of the jaws. The larger pair of electrodes are capable of effecting vessel sealing (e.g., capable of producing Ligasure™-quality tissue welds) while the smaller electrodes are well-adapted to effecting coagulation, e.g., to minimize blood in the surgical field. The disclosed instrument may include be equipped with an electrode and/or a blade capable of performing electrosurgical tissue division. The intended use of this device could be any surgical procedure where maintaining a quality seal is necessary on only one side of the device. An example of this is a polypectomy or lung wedge resection, where the excised portion of tissue would have minimal seal width and possibly reduced thermal spread for better assessment of disease states and margins. This may also allow the maximum seal width to be formed on the patient side of a resection while maintaining an overall smaller device footprint, a slimmer end effector and/or jaw assembly, and the like. 
         [0013]    Desirably, at least one of the jaw members is made from a hard anodized aluminum having high dielectric properties. It is envisioned that the electrodes include a non-stick coating disposed thereon which is designed to reduce tissue adherence. 
         [0014]    According to another aspect of the present disclosure, an electrosurgical forceps is disclosed. The disclosed forceps includes a shaft having a first and a second opposing jaw member at a distal end thereof. Each jaw member includes an outer housing, and an inner tissue engaging surface. Each jaw&#39;s inner tissue engaging surface corresponds to the inner tissue engaging surface of the opposite jaw. The forceps includes a drive assembly for moving the jaw members relative to one another from a first open position to a second closed position wherein the jaw members cooperate to grasp tissue therebetween. The jaws include an electrode disposed on the inner tissue engaging surface having a first contact region disposed adjacent to a first edge of the inner tissue engaging surface, and a second contact region disposed adjacent to a second edge of the inner tissue engaging surface. The surface area of the first contact region is greater than the surface area of the second contact region. 
         [0015]    According to another embodiment, disclosed is an electrosurgical forceps having a shaft and a pair of opposing jaw members at a distal end thereof. Each jaw member includes an outer housing, and an inner tissue engaging surface corresponding to the inner tissue engaging surface of the opposing jaw. The forceps includes a drive assembly for moving the jaw members relative to one another from a first, open position to a second, closed position wherein the jaw members cooperate to grasp tissue therebetween. Each jaw includes a first electrode disposed on an inner tissue engaging surface and disposed adjacent to a first edge of the inner tissue engaging surface, and a second electrode disposed on an inner tissue engaging surface and disposed adjacent to a second edge of the inner tissue engaging surface. The surface area of the first electrode is greater than the surface area of the second electrode. 
         [0016]    Also disclosed is a method of operating an electrosurgical forceps, comprising the steps of providing an electrosurgical forceps having a shaft having a first and a second opposing jaw member at a distal end thereof. Each jaw member of the provided forceps includes an outer housing, and an inner tissue engaging surface corresponding to the inner tissue engaging surface of the opposing jaw. The provided forceps includes a drive assembly for moving the jaw members relative to one another from a first, open position to a second, closed position wherein the jaw members cooperate to grasp tissue therebetween. A first electrode is operably coupled to a source of electrosurgical energy and disposed on the inner tissue engaging surface of the first jaw. The first electrode has a first contact region disposed adjacent to a first edge of the inner tissue engaging surface of the first jaw, and a second contact region disposed adjacent to a second edge of the inner tissue engaging surface of the first jaw. The surface area of the first contact region of the first electrode is greater than the surface area of the second contact region thereof. A second electrode is operably coupled to a source of electrosurgical energy and disposed on the inner tissue engaging surface of the second jaw. The second electrode has a first contact region disposed adjacent to a first edge of the inner tissue engaging surface of the second jaw, and a second contact region disposed adjacent to a second edge of the inner tissue engaging surface of the second jaw. The surface area of the first contact region of the second electrode is greater than the surface area of the second contact region thereof. The method includes the steps of closing the jaws to grasp tissue therebetween, and applying electrosurgical energy to tissue via the first electrode and the second electrode to cause a change to the tissue. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Various embodiments of the subject instrument are described herein with reference to the drawings wherein; 
           [0018]      FIG. 1  is a left, perspective view of an embodiment of a bipolar electrosurgical instrument in accordance with the present disclosure showing a housing, a shaft and a jaw assembly having an asymmetrical electrode; 
           [0019]      FIG. 2  is an enlarged, left perspective view of an embodiment of a jaw assembly having an asymmetrical electrode in accordance with the present disclosure; 
           [0020]      FIG. 3  is an enlarged, partially-exploded view of the  FIG. 2  embodiment of a jaw assembly having an asymmetrical electrode in accordance with the present disclosure; 
           [0021]      FIG. 4  is an enlarged, left perspective view of another embodiment of a jaw assembly having an asymmetrical electrode in accordance with the present disclosure; 
           [0022]      FIG. 5  is an enlarged, partially-exploded view of the  FIG. 4  embodiment of a jaw assembly having an asymmetrical electrode in accordance with the present disclosure; 
           [0023]      FIG. 6A  is an enlarged, cross-sectional view of the distal end of a jaw assembly in accordance with the present disclosure showing a knife assembly in a proximal position prior to the actuation thereof; 
           [0024]      FIG. 6B  is an enlarged, cross-sectional view of the distal end of a jaw assembly in accordance with the present disclosure showing a knife assembly in a distal position subsequent to the actuation thereof; and 
           [0025]      FIG. 7  is a perspective view of another embodiment of a bipolar electrosurgical instrument in accordance with the present disclosure having a jaw assembly that includes an asymmetrical electrode. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings, however, it is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. 
         [0027]    In the drawings and in the descriptions that follow, the term “proximal,” as is traditional, shall refer to the end of the instrument that is closer to the user, while the term “distal” shall refer to the end that is farther from the user. Similar reference numbers are used for elements that are the same or similar to elements illustrated or described herein. In addition, as used herein, terms referencing orientation, e.g., “top”, “bottom”, “up”, “down”, “left”, “right”, “clockwise”, “counterclockwise”, “upper”, “lower”, and the like, are used for illustrative purposes with reference to the figures and features shown therein. It is to be understood that embodiments in accordance with the present disclosure may be practiced in any orientation without limitation. 
         [0028]    Referring to  FIG. 1 , a bipolar surgical instrument  10  is shown generally and includes a housing  20 , a handle assembly  30 , a trigger assembly  70 , a rotating assembly  80 , and an end effector assembly  90 , such as, without limitation, a forceps or hemostat, which mutually cooperate to grasp, seal, and/or divide tubular vessels and vascular tissue. As shown, handle assemblies  30  of instrument  10  are of the pistol grip-type, however, any suitable type of handle is envisioned within the scope of the present disclosure. The handle assembly  30  offers a surgeon a gripping position from which to grasp instrument  10  and to transmit a clamping pressure to end effector assembly  90 . Instrument  10  includes a shaft  12 , which has a distal end  14  configured to mechanically engage end effector assembly  90 , and a proximal end  16  configured to mechanically engage housing  20 . 
         [0029]    As depicted in  FIG. 1 , shaft  12  of instrument  10  is relatively elongated. The relatively elongated shaft  12  of instrument  10  enables instrument  10  to be used in performing endoscopic surgical procedures. Shaft  12  may alternatively have a shorter, or longer, shaft than that shown in  FIG. 1 , which may be desirably utilized in various endoscopic and/or open surgical procedures. Rotating assembly  80  is attached to a distal end of housing  20  and is rotatable in either direction about a longitudinal axis of the shaft  12 . In some embodiments, rotating assembly  80  is rotatable approximately 180 degrees in either direction about a longitudinal axis of the shaft  12 . Rotation of rotating assembly  80  correspondingly rotates jaw assembly  90  about the longitudinal axis of shaft  12 . In some embodiments, as seen in  FIGS. 2 and 3 , shaft  12  is bifurcated at distal end  14  thereof to form ends  14   a  and  14   b,  which are configured to receive jaw assembly  90 . 
         [0030]    Instrument  10  further may include an electrical cable  60  extending from housing  20  which couples instrument  10  to a source of electrosurgical energy, e.g., a generator (not explicitly shown). In some embodiments, a source of electrosurgical energy (not explicitly shown), and/or a power source, such as without limitation, a rechargeable battery (not shown), may be included within instrument  10 , e.g., within the housing  20  thereof. 
         [0031]    Handle assembly  30  includes a first handle  50  and a second handle  40 . Second handle  40  is selectively movable about a pivot (not shown) from a first position in spaced relation relative to first handle  50  to a second position in closer proximity relative to first handle  50  which imparts movement of jaw members  210  and  220  relative to one another, e.g., from an open to closed position about tissue. As shown in greater detail in  FIG. 2 , jaw assembly  90  is attached to distal end  14  of shaft  12  and includes a pair of opposing jaw members  210  and  220 . For illustrative purposes, jaw member  210  may be referred to as an upper jaw member  210  and jaw member  220  may be referred to as a lower jaw member  220 . First and second handles  40 ,  50  are ultimately connected to a drive rod (not explicitly shown) which, together, mechanically cooperate to impart movement of jaw members  210 ,  220  from an open position wherein the jaw members  210 ,  220  are disposed in spaced relation relative to one another, to a clamping or closed position wherein, e.g., jaw members  210 ,  220  cooperate to grasp tissue therebetween. 
         [0032]    Jaw members  210  and  220  are seated within a cavity  18  defined between bifurcated ends  14   a  and  14   b  of shaft  12 . Jaw members  210  and  220  include mutually corresponding component features which cooperate to permit rotation about a pivot pin  260  to effectively grasp, seal, and/or divide tissue. Jaw members  210 ,  220  each include a jaw housing  216 ,  226 , an insulative substrate or insulator  214 ,  224  and an electrically conductive surface or electrode  212 ,  222 . Insulators  214 ,  224  are configured to securely engage the electrodes  212 ,  224 . This may be accomplished by, e.g., stamping, by overmolding, by overmolding a stamped electrically conductive sealing plate and/or by overmolding a metal injection molded seal plate. Such manufacturing techniques produce a jaw assembly having an electrode  212 ,  222  which is substantially surrounded by an insulating substrate  214 ,  224 . Insulating substrate  214 ,  224 , electrode  212 ,  222 , and the outer, non-conductive jaw housings  216 ,  226  are preferably configured to limit and/or reduce many of the known undesirable effects related to tissue sealing, e.g., flashover, thermal spread and stray current dissipation. Alternatively, jaw members  210  and  220  may be manufactured from a ceramic-like material and electrically conductive surfaces  212 ,  222  coated onto the ceramic-like jaw members  210 ,  220 . 
         [0033]    Electrodes  212 ,  222  may also include an outer peripheral edge which has a radius and insulators  214 ,  224  that meet electrodes  212 ,  222  along an adjoining edge which is generally tangential to the radius and/or meets along the radius. At the interface, electrodes  212 ,  222  are raised relative to insulator  214 ,  224 . 
         [0034]    Jaw members  210 ,  220  may be electrically isolated from one another such that electrosurgical energy can be effectively transferred through the tissue to form the seal. Electrodes  212 ,  222  of jaw members  210 ,  220 , respectively, may be relatively flat to avoid current concentrations at sharp edges and to avoid arcing between high points. In addition, and due to the reaction force of the tissue when engaged, jaw members  210 ,  220  may be manufactured to resist bending. For example, jaw members  210 ,  220  may be tapered along the width thereof which is advantageous for two reasons: 1) the taper will apply constant pressure for a constant tissue thickness at parallel, and 2) the thicker proximal portion of jaw members  210 ,  220  will resist bending due to the reaction of the tissue. 
         [0035]    Jaw members  210 ,  220  may be curved in order to reach specific anatomical structures. For example, dimensioning jaws  210 ,  220  at an angle of about 50 degrees to about 70 degrees is preferred for accessing and sealing specific anatomical structures relevant to prostatectomies and cystectomies, e.g., the dorsal vein complex and the lateral pedicles. 
         [0036]    As best seen in example embodiments shown in  FIGS. 2 and 3 , electrodes  212 ,  222  include a first, larger contact area  212   a,    222   a  and a second smaller contact area  212   b,    222   b.  Larger contact areas  212   a,    222   a  are arranged in a mutually corresponding configuration with respect to jaw members  210 ,  220  such that contact area  212   a  mates with contact area  222   a  when jaw members  210 ,  220  are in a closed position, e.g., when grasping tissue therebetween. Similarly, smaller contact areas  212   b  and  222   b  are arranged in a mutually corresponding configuration such that contact area  212   b  mates with contact area  222   b  when jaw members  210 ,  220  are in a closed position. During use, the larger contact areas of electrodes  212   a,    222   a  may be used to grasp the patient-side of a vessel and/or the smaller contact areas of electrodes  212   b,    222   b  may be used to grasp tissue, vessels, etc. slated for resection. During a vessel sealing procedure, the larger contact areas of electrodes  212   a,    222   a  enable the delivery of electrosurgical energy at a density sufficient to form a burst-resistant vessel seal on the patient side of the jaws. Conversely, the narrower electrodes  212   b,    222   b  enable the delivery of electrosurgical energy to the resection side of the jaw members  210 ,  200  to produce a smaller seal. 
         [0037]    In one envisioned embodiment, the size ratio of the larger contact area  212   a,    222   a  to the second smaller contact area  212   b,    222   b  is about 3:1, however, the size ratio may be in a range of about 1.2:1 to about 10:1 and in some embodiments may range up to 100:1 or greater. In some embodiments, the width ratio of the width of the larger contact area  212   a,    222   a  to the second smaller contact area  212   b,    222   b  is about 3:1, however, the width ratio may be in a range of about 1.2:1 to about 10:1 and in some embodiments may range up to 100:1 or greater. 
         [0038]    A conductor  310   a  electrically couples electrode  212  (which includes wide electrode  212   a  and narrow electrode  212   b ) to a source of electrosurgical energy as described hereinabove. Similarly, conductor  310   b  electrically couples electrode  222  (e.g., wide electrode  222   a  and narrow electrode  222   b ) to a source of electrosurgical energy. 
         [0039]    In another aspect, jaw housings  216 ,  226  include a visual indicator  218   a  and  218   b  that is configured to enable a surgeon to readily ascertain jaw member orientation. In the example embodiment depicted in  FIGS. 2 and 3 , visual indicator  218   a  includes an intaglio arrowhead icon formed in an outer surface of jaw housing  216  that indicates the position of the wide electrode  212   a.  Similarly, visual indicator  212   b  includes an intaglio arrowhead icon formed in an outer surface of jaw housing  216  that indicates the position of narrow electrode  212   b.  As shown in the drawings, indicators  218   a  and  218   b  indicate the wide and narrow electrodes  212   a,    212   b  by using corresponding wide and narrow arrows  218   a,    218   b.  The visual indicators  218   a,    218   b  may include arrows, or may include any other icon to represent the wide and narrow electrodes  212   a,    212   b,  respectively. The design of visual indicators  218   a,    218   b  may include a mnemonic element that enables “at a glance” intuitive interpretation by the surgeon. Other envisioned indicators include a large circle/small circle, single bar/double bar, pictograph, different colors, and so forth. While not explicitly shown in the figures, visual indicators may be included in lower jaw member  226  to enable a surgeon to identify electrode orientation regardless of the rotated position of the jaw member  216 ,  226 . Additionally or alternatively, visual indicators  218   a,    218   b  may be formed by any suitable marking technique, e.g., in raised relief, laser etching, stamping, molding, machining, pigment, ink, dye, overmolding, and the like. Additionally or alternatively, visual indicators  218   a,    218   b  may be positioned on shaft  12  and/or rotating assembly  80  as long as they correspond to jaw member orientation. 
         [0040]    As seen in  FIGS. 2 and 3 , in order to achieve a desired gap range (e.g., about 0.001 to about 0.006 inches) and apply a desired force to seal the tissue, at least one jaw member  210  and/or  220  includes one or more stop members  239  that limit the movement of the two opposing jaws  210 ,  220  relative to one another. Each stop member  239  is made from an insulative material and is dimensioned to limit opposing movement of jaw members  210 ,  220  to within the above gap range. 
         [0041]    A knife channel  215  may be defined through the center of jaw member  220  such that a knife  305  having a distal cutting edge  306  may cut through the tissue grasped between jaw members  210  and  220  when jaw members  210  and  220  are in a closed position, as illustrated with reference to  FIGS. 6A and 611 . Details relating to the knife channel  215 , knife  305 , trigger assembly  70 , and a knife actuation assembly associated therewith (not explicitly shown) are explained in limited detail herein and explained in more detail with respect to commonly-owned U.S. Pat. Nos. 7,156,846 and 7,150,749 to Dycus et al. 
         [0042]    Housing  20  is formed from two housing halves that engage one another via a series of mechanical interfaces to form an internal cavity for housing the internal working components of instrument  10 . For the purposes herein, the housing halves are generally symmetrical and, unless otherwise noted, a component described with respect to a first of the housing halves will have a similar component which forms a part of a second of the housing halves. 
         [0043]    As mentioned above, first handle  50  and second handle  40  of handle assembly  30  cooperate with one another and with housing  20  to activate a first mechanical linkage (not shown) which, in turn, actuates a drive assembly (not shown) for imparting movement of opposing jaw members  210 ,  220  relative to one another to grasp tissue therebetween. 
         [0044]    Handle assembly  130  further includes a trigger assembly  70  that cooperates with a knife actuation assembly (not explicitly shown) which enables the extension of knife  305  from a first, proximal, position as depicted in  FIG. 6A , to a second, distal position as depicted in  FIG. 6B  to sever tissue grasped between jaw members  210 ,  220 . Knife  305  travels within knife channel  215  formed within jaws  210 ,  220 . In an embodiment, trigger assembly  70  may include a lockout (not explicitly shown) that inhibits actuation of knife  305  while jaws  210 ,  220  are in an open position. 
         [0045]    As discussed above, by controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue, the surgeon can cauterize, coagulate, desiccate, seal and/or simply reduce or slow bleeding. In addition, the disclosed instrument may be operated in one of a plurality of polarity configurations to achieve specific surgical objectives. For example, in a vessel sealing configuration, electrodes  212   a  and  212   h  (associated with upper jaw member  210 ) have a positive polarity (e.g., active electrodes) while electrodes  222   a  and  222   b  (associated with lower jaw member  220 ) have a negative polarity (e.g., return electrodes.) In this generally bipolar configuration, blade  305  is electrically deactivated and severs tissue by physically cutting tissue (e.g., vessel) held between jaws  210 ,  220 . Additionally or alternatively, electrosurgical energy is delivered to a vessel grasped between jaws  210 ,  220  to effectuate the sealing of the vessel. 
         [0046]    In another configuration adapted for cutting, blade  305  is electrically coupled to a source of electrosurgical energy to form an active (e.g., positive) electrode. Electrodes  212   a,    212   b,    222   a,  and  222   b  are configured as a negative, or return, electrode, During use, blade  305  effectuates cutting via cutting edge  306  and/or the electrosurgical cutting energy delivered between blade  305 , cutting edge  306 , and electrodes  212   a,    212   b,    222   a,  and  222   b.    
         [0047]    In yet another embodiment depicted in  FIGS. 4 and 5 , a jaw assembly  290  includes an upper jaw member  310  and a lower jaw member  320 . Upper jaw member includes an electrode array  312  having two independent electrodes  312   a  and  312   b.  Electrode  312   a  has a greater surface area than the narrower electrode  312   b.  Correspondingly, lower jaw member  320  includes a electrode array  322  having two independent electrodes  322   a  and  322   b,  wherein electrode  322   a  has a greater surface area than the narrower electrode  322   b.  As can be appreciated, electrode arrays  312  and  322  are arranged in a mutually corresponding configuration wherein electrode  312   a  mates with electrode  322   a,  and electrode  312   b  mates with electrode  322   b,  when the jaw members  310  and  320  are in a closed configuration. 
         [0048]    Each of the four electrodes  312   a,    312   b,    322   a,  and  322   b  are independently coupled to one or more sources of electrosurgical energy. As seen in  FIG. 5 , electrode  312   a  is coupled to a source of electrosurgical energy by a conductor  410   a,  and electrode  312   b  is coupled to a source of electrosurgical energy by a conductor  411   a.  Electrodes  322   a  and  322   b  are coupled to a source of electrosurgical energy by conductors  410   b  and  411   b,  respectively. In an envisioned embodiment, electrodes  312   a,    312   b,    322   a,  and  322   b  and knife  405  may be independently selectively assigned to a positive or negative polarity (e.g., designated as an active or return electrode.) In this embodiment a total of 32 electrode configurations are available to the surgeon. 
         [0049]    For example, and without limitation, wide electrodes  312   a  and  322   a  may be configured in a bipolar arrangement to facilitate vessel sealing on the patient side. On the resection (narrow electrode) side, blade  405  may be configured as an active (+) electrode while narrow electrodes  312   b  and  322   b  are configured as a return (−) electrode. 
         [0050]    In another embodiment, electrodes may be alternatively or sequentially energized, either individually or in combination, to achieve effectively simultaneous cutting, coagulating, sealing, etc. In another non-limiting example, a source of electrosurgical energy may be configured to provide, during a first time period, vessel sealing energy to a first pair of electrodes  312   a  and  322   a;  during a second time period, the source of electrosurgical energy provides coagulation energy to a second pair of electrodes  312   b  and  322   b;  and during a third time period, the source of electrosurgical energy provides cutting energy, e.g., sending positive cutting energy to knife  405  and receiving negative cutting energy at electrodes  312   a,    322   a,    312   b,  and  322   b.  The time periods may be of any duration, however it is envisioned that a time period may have a duration of about 0.001 second to about 0.1 second, and continue in round robin fashion during activation (e.g., while activated by the surgeon.) Various electrode combinations, energy profiles, and sequences thereof may be specified, modified, and/or stored for later recall and use by a surgeon. 
         [0051]      FIG. 7  illustrates another embodiment of an electrosurgical instrument  400  in accordance with the present disclosure. Instrument  400  has a generally scissors-like or hemostat-like structure suitable for use in open surgical procedures. Instrument  400  includes elongated shaft portions  440  and  450  each having a proximal end  441  and  451 , respectively, and a distal end  442  and  452 , respectively. The instrument  400  includes an end effector assembly  490  which is operably coupled to distal ends  442  and  452  of shafts  440  and  450 , respectively. The end effector assembly  490  includes pair of opposing jaw members  410  and  420  which are pivotably connected about a pivot pin  430 . The two opposing jaw members  410  and  420  of the end effector assembly  490  are pivotable about pin  430  from the open position to the closed position for grasping tissue therebetween. Jaw members  410  and  420  include asymmetrical electrodes (not explicitly shown) arranged as described hereinabove that may be coupled to a source of electrosurgical energy by cable assembly  460 . In some embodiments, a source of electrosurgical energy and/or a power source may be included in instrument  400  for “wireless” use. Instrument  400  may include at least one handswitch  480 , which may be a slide switch or a pushbutton switch, that is adapted to activate the delivery of electrosurgical energy to tissue. Instrument  400  may additionally or alternatively include a knife actuator  470  that is adapted to actuate a knife (not shown) for dividing tissue grasped between jaws  410  and  420 . 
         [0052]    While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.