Abstract:
An electrosurgical electrode capable of vaporization, coagulation, desiccation or cutting of tissue is disclosed. The probe has a first portion configured for tissue vaporization, and a second portion configured for tissue desiccation or coagulation. Simultaneous vaporization and desiccation may be achieved, the balance between the effects being controlled by the orientation and motions of the electrode. The electrode may have irrigation and aspiration means.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to the field of electrosurgery, and, more particularly, to high efficiency surgical devices and methods which use of high frequency (RF) electrical power for cutting, bulk removal by vaporization with externally supplied conductive liquid irrigants. 
   The present invention provides a system and method for performing electrosurgical cutting, ablation (volumetric tissue vaporization), coagulation or modification within or on the surface of a patient. The system and method of the invention herein disclosed may be used in relatively dry environments, for instance, for oral, otolaryngological, laparoscopic, and dermatologic procedures. 
   Electrosurgical procedures require a proper electrosurgical generator, which supplies the Radio Frequency (RF) electrical power, and a proper surgical electrode (also known as an electrosurgical probe). Under appropriate conditions the desired surgical effects are accomplished. 
   Note: in common terminology and as used herein the term “electrode” may refer to one or more components of an electrosurgical device (such as an active electrode or a return electrode) or to the entire device, as in an “ablator electrode”. Electrosurgical devices may also be referred to as “probes”. 
   An electrosurgical probe, in general, is composed of a metallic conductor surrounded by a dielectric insulator (for example plastic, ceramic or glass) except for the exposed metallic electrode. The probe electrode is often immersed in a conducting fluid, either filling a natural or created cavity or applied as irrigant to a “dry” site, and is brought in contact with or close proximity to the tissue structure during the electrosurgical procedure. The probe is energized, typically at a voltage of few hundred to a few thousand volts, using an RF generator operating at a frequency between 100 kHz to over 4 MHz. This voltage induces a current in the conductive liquid and nearby tissue. This current heats the liquid and tissue, the most intense heating occurring in the region very close to the electrode where the current density is highest. At points where the current density is sufficiently high, the liquid boils locally and many steam bubbles are created, the steam bubbles eventually insulating part or all of the electrode. Electrical breakdown in the form of an arc (spark) occurs in the bubbles which insulate the electrode. The sparks in these bubbles are channels of high temperature ionized gas, or plasma (temperature of about a few thousand degrees Kelvin). These high current density sparks, heat, vaporize (ablate) or cut the tissue (depending on the specific surgical procedure and the probe geometry) that is in contact with the spark or the adjacent heated fluid. 
   Many surgical procedures are not performed inside a natural or formed body cavity and as such are not performed on structures submerged under a conductive liquid. In laparoscopic procedures, for instance, the abdominal cavity is pressurized with carbon dioxide to provide working space for the instruments and to improve the surgeon&#39;s visibility of the surgical site. Other procedures, such as oral surgery, the ablation and necrosis of diseased tissue, or the ablation of epidermal tissue, are also typically performed in an environment in which the target tissue is not submerged. In such cases it is necessary to provide a conductive irrigant to the region surrounding the active electrode(s), and frequently also to aspirate debris and liquid from the site. Such irrigant may be applied by a means external to the instrument; however, having an irrigation means internal or attached to the instrument generally provides better control and placement. This is also true for aspiration of fluid and debris. External means may be used for aspiration from the site; however, aspiration through the instrument distal end provides improved fluid control and may, in some cases, draw tissue toward the active electrode thereby enhancing performance. 
   Electrosurgical devices having a means for irrigating a site, and/or means for aspirating fluid, bubbles and debris from a site are well known. Smith in U.S. Pat. No. 5,195,959 teaches an electrosurgical device with suction and irrigation. Bales, et al in U.S. Pat. No. 4,682,596 teach a catheter for electrosurgical removal of plaque buildup in blood vessels, the catheter having lumens for supplying irrigant to the region of the instrument distal tip and for aspirating debris from the region. Hagen in U.S. Pat. No. 5,277,696 teaches a high frequency coagulation instrument with means for irrigation and aspiration from the region of the instrument tip. Pao in U.S. Pat. No. 4,674,499 teaches a coaxial bipolar probe with suction and/or irrigation. Eggers in U.S. Pat. No. 6,066,134 teaches a method for electrosurgical cutting and coagulation which uses a bipolar probe having means for irrigating and aspirating from the region of the probe distal tip. The Eggers device uses the irrigant flow to provide a return path to a return electrode recessed axially a distance away from the active electrode(s). 
   One application of electrosurgical technique is the removal of a portion of tissue from a vascular surrounding tissue bed in a “dry” environment, that is, in an environment in which conductive irrigant is supplied to the surgical site. Such removal requires the effective vaporization of connecting tissue to allow removal of the tissue portion, and also coagulation of the adjacent remaining tissue to prevent bleeding. Debris and irrigant are removed from the site by aspiration, either by a means external to the electrosurgical instrument or through external means. 
   It is accordingly an object of this invention to produce an electrosurgical probe which is able to effect the removal of a tissue portion from a surrounding vascular bed while minimizing bleeding. 
   It is also an object of this invention to produce an electrosurgical probe which has a simple structure so that it is producible at low cost. 
   It is additionally an object of this invention to produce an electrosurgical probe in which tissue may be either vaporized or coagulated through selection of the probe surface in contact with the tissue. 
   SUMMARY OF THE INVENTION 
   These and other objects are achieved in the invention herein disclosed which is an electrosurgical device for the cutting, bulk vaporization, and coagulation of tissue at a surgical site, conductive irrigant being supplied to the site via means within the device, and debris and fluid aspirated from the site by means within the device. The device has a distal tip having a first portion with ribs, grooves, protrusions or other features for creating regions of high current density capable of high efficiency vaporization of tissue, and a second portion having a surface suited for coagulation or thermal treatment of tissue. In use the surgeon affects tissue with the first surface to separate tissue from a surrounding bed, and to vaporize selected tissue. The surgeon affects tissue with the second surface to coagulate the remaining tissue to prevent bleeding. The surgeon may use both surfaces simultaneously. In other embodiments irrigant is supplied by means external to the probe. In still other embodiments aspiration is supplied by means external to the probe. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows an electrosurgical system formed in accordance with the principles of this invention. 
       FIG. 2  is a plan view of an electrosurgical probe formed in accordance with the principles of this invention. 
       FIG. 3  is a perspective view of the objects of  FIG. 2 . 
       FIG. 4  is an expanded side elevation view of the distal portion of the probe of  FIG. 2 , the probe being positioned vertically as for use, for instance, in removing a tonsil from the tonsilar bed. 
       FIG. 5  is a top axial view of the objects of  FIG. 4 . 
       FIG. 6  is a bottom end axial view of the objects of  FIG. 4 . 
       FIG. 7  is an elevational view of the first surface of the objects of  FIG. 4  configured for the vaporization of tissue. 
       FIG. 8  is an elevational view of the second surface of the objects of  FIG. 4  configured for the coagulation or thermal treatment of tissue. 
       FIG. 9  is a perspective view of the objects of  FIG. 4  showing the first surface. 
       FIG. 10  is a perspective view of the objects of  FIG. 4  showing the second surface. 
       FIG. 11  is an elevational sectional view at location A-A of  FIG. 7 , in direction A-A showing the irrigation means. 
       FIG. 12  is an elevational sectional view at location B-B of  FIG. 7  in direction B-B showing the aspiration means. 
       FIG. 13  is an expanded elevational view of the distal portion of the instrument of  FIG. 2  during use when primarily vaporizing tissue. 
       FIG. 14  is an expanded elevational view of the distal portion of the instrument of  FIG. 2  during use when primarily cutting and coagulating tissue. 
       FIG. 15  is an expanded elevational view of the distal portion of the instrument of  FIG. 2  during use when primarily coagulating tissue. 
       FIG. 16  is an expanded elevational view of the distal portion of an alternate embodiment. 
       FIG. 17  is an distal axial view of the object of  FIG. 16 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the figures, as seen in  FIG. 1 , electrosurgical system  100  has an electrosurgical generator  102  connected to electrosurgical probe  10  by cable  124 , an irrigant source  104  connected by tube  126  to probe  10 , and a vacuum source  106  connected by tube  128  to probe  10 . Control of the generator by probe  10 , and control of the vacuum source and irrigant flow are conventional and not elements of the invention herein disclosed. A return electrode, not shown, is attached to the patient at a site remote from the surgical site. 
   As seen in  FIGS. 2 and 3 , electrosurgical instrument  10  formed in accordance with the principles of this invention, has a proximal portion  12  forming a handle having a proximal end  14  and a distal end  16 , and an elongated distal portion  18  having a proximal end  20  and a distal end  22 . Proximal end  20  of distal portion  18  is rigidly affixed to distal end  16  of handle  20 . Proximal end  14  of handle  12  has passing therefrom cable  24  which connects to electrosurgical generator  102  ( FIG. 1 ), first tube  26  connects to irrigant source  104 , and second tube  28  connects to vacuum source  106 . Near distal end  16  of portion  12 , first activation button  30  and second activation button  32  are connected via cable  24  to electrosurgical unit  102 . Distal end  22  of elongated distal portion  18  comprises an active electrode  34 . 
   Referring now to  FIGS. 4 through 10 , distal end  22  of probe  10  has an electrode  34  having a proximal end  36  assembled to rectangular tube  38  which extends from electrode  34  to the handle portion  12  of probe  10 , and a distal end  40 . Electrode  34  has a first surface portion  42  having a distal portion  44  in which are formed grooves  46  and ribs  48 . Electrode  34  has a second surface portion  50  having a smooth convex contour. Distal-most edge  52  formed by the intersection of surfaces  42  and  50  has an included angle  53  and has teeth  54  formed by ribs  48 . In a preferred embodiment included angle is between 20 and 110 degrees, and more preferably between 30 and 90 degrees. Edge  52  forms an angle  55  with axis  57  of tube  38  when viewed as in  FIG. 8 . In a preferred embodiment angle  55  is between 30 and 90 degrees, and more preferably between 45 and 90 degrees. In other embodiments distal-most edge  52  is curvilinear. First surface  42  has formed therein, distance  56  from distal end  40 , irrigation port  58 . Second surface portion  50  has formed therein, distance  59  from distal end  40 , irrigation port  60 . Referring now to  FIG. 11 , irrigation ports  58  and  60  are in communication via lumen  62  with tube  64  which is connected via means within probe handle  12  to tube  26  and there through to irrigant source  104 . First lateral surface  65  has positioned therein distance  66  from distal end  40  aspiration port  68 . Second lateral surface  69  has positioned therein distance  66  from distal end  40  aspiration port  70 . Distance  66  is preferably between one and four millimeters, and more preferably between one and two millimeters. Referring now to  FIG. 12 , aspiration ports  68  and  70  are connected by passage  72  to lumens  74  and  76  which are in communication with lumen  78  of rectangular tube  38 , which in turn is in communication via means within probe handle portion  12  with tube  28  and therethrough with vacuum source  106 . Tube  38  and the proximal portion  36  of electrode piece  34  are covered with a dielectric coating. Distal portion  80  of electrode  34  is offset from proximal portion  36  angle  82 . 
   Electrode  34  is formed of a monolithic, homogeneous metallic material such as stainless steel, titanium, nickel, or tungsten. Electrode  34  may be formed by machining from bar stock or from or a casting, however, a preferred method of manufacture is Metal Injection Molding (abbreviation “MIM”). Electrode  34  is molded complete with proximal portion  36  and distal portion  80  co-linear. This allows lumens  74  and  76  to be formed in the mold as cylindrical passages. After molding and sintering of electrode  34 , electrode  34  is bent so that distal portion  80  is offset from proximal portion  36  at angle  82 . This method of manufacture allows electrode  34  to be produced at low cost since no conventional machining is required. 
   Probe  10  is used in a more or less vertical orientation to remove a tissue portion from surrounding vascular tissue. Referring now to  FIG. 12 , during use, irrigant  83  supplied to the site via irrigation ports  58  and  60  flows down surface portions  42  and  50  respectively so as to bathe distal-most portion  84  and tissue in close proximity in conductive liquid. Liquid  85  is removed from the region via aspiration ports  68  and  70 . When RF power is applied, tissue in contact with distal portion  44  of first surface portion  42  is vaporized, while tissue in contact with second surface portion  50  is desiccated so as to prevent bleeding. The relative portion of power used for vaporization and desiccation is determined by the amount of tissue in contact with the two regions of the electrode  34 . This, in turn, is determined by the surgeon&#39;s technique, and more particularly, largely by the orientation of the probe relative to the motion with which the surgeon advances the probe into the tissue. For instance, in  FIG. 12  depicting tissue portion  89  during removal from tissue bed  90 , a separating force  92  is applied to portion  88 . Probe  10  is used to separate portion  89  from bed  90 . Probe  10  and electrode  34  are advanced into the tissue with a motion  93  which is at angle  88  to a perpendicular  94  to the axis of tube  38 . This relative motion causes little tissue to be in contact with surface  50 . This, in turn, causes most of the RF energy to be expended in vaporization of tissue at second surface  58 . Desiccation of tissue at surface  50  is minimal. 
   Referring now to  FIG. 14  depicting the removal of tissue portion  89  from tissue bed  90 , probe  10  is advanced into the tissue with motion  93  at angle  88  to perpendicular  94  to the axis of tube  38 . This relative motion causes more tissue to be in contact with surface  50  thereby causing more desiccation of tissue in this region. This, in turn, causes decreased bleeding from the tissue bed which has been resected. 
   In  FIG. 15  only surface  50  is in contact with tissue as the surgeon uses the probe tip to “paint” the surface to desiccate the tissue and stop bleeding. The relative motion imparted by the surgeon is essentially parallel to the resected surface. No tissue vaporization occurs. 
   In use, then, the surgeon is able to control the relationship between vaporization and desiccation through orientation of probe  10  and relative motion between the probe and tissue being resected. The probe can vaporize tissue aggressively with minimal desiccation, or can be used in a manner which produces more desiccation with less aggressive vaporization. The probe can also be used to desiccate resected surfaces by painting them with second surface  50 . 
     FIGS. 16 and 17  show the distal portion  44  of an alternate embodiment having additional aspiration ports  96  between ribs  48 . Ports  96  are in communication with lumen  72  ( FIG. 12 ) so as to provide additional aspiration of fluid. In other embodiments aspiration ports  68  and  70  are eliminated and all aspiration is through ports  96 . In some applications aspiration is not required or is supplied by an external device. In other embodiments for such applications, probe  10  does not have an aspiration means. 
   Modifications may be made to the irrigation means of probe  10 . For instance, in other embodiments irrigation is by a tubular member external to tube  38 . In one embodiment the tubular member is coaxial with tube  38  and fluid is introduced through a gap between tube  38  and the external tube. In other embodiments a tube having an axis parallel to that of tube  38  is affixed to the external surface of tube  38  to create a flow path to distal end  22  of probe  10 . 
   Distal portion  44  of first surface  42  has formed therein grooves  46  and ribs  48  configured to provide regions of high current density for enhanced vaporization of tissue. The ribs may have cross-sectional shapes other than the rectangular shape of the previously disclosed embodiments. For instance, the ribs may have triangular, trapezoidal or irregular cross-sections. Other protuberances having axes approximately normal to distal portion  44  of surface  42  may also be used to provide regions of high current density. These may include cylindrical protrusions, or protrusions having cross-sections which are triangular, trapezoidal, or irregular.