Abstract:
An electrosurgical apparatus for coagulating tissue includes an elongated flexible tube having a proximal end, a distal end and a source for supplying pressurized ionizable gas to the proximal end of the tube. The apparatus also includes a hollow sleeve made from a shape memory alloy having a generally curved austenite state and displaying stress-induced martensite behavior. The hollow sleeve is restrained in a deformed stress-induced martensite configuration within the tube and partial extension of a portion of the hollow sleeve from the tube transforms the portion of the sleeve from the deformed configuration to the generally curved austenite configuration such that the gas is directed transversely at the tissue. An electrode ionizes the gas in the region between the sleeve and the tissue. Other embodiments of the present disclosure also include a wire connected to the distal end of the tube which movable from a first postion wherein the tube is disposed in a generally rectilinear, parallel fashion relative to the tissue to a second retracted position wherein the distal end of the tube flexes at an angle to direct the gas towards the tissue. Still other embodiments of the present disclosure include a corona electrode for inducing ignition of the gas.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 10/282,288 filed on Oct.28, 2002 now U.S. Pat. No. 6,911,029 by Robert C. Platt, which is a continuation of U.S. patent application Ser. No. 09/665,380 filed on Sep. 21, 2000 now U.S. Pat. No. 6,475,217 by Robert C. Platt, which claims priority to U.S. Provisional Application Ser. No. 60/157,743 filed on Oct. 5, 1999, the entire contents of all of which are hereby incorporated by reference herein. 
    
    
     The present disclosure relates to gas-enhanced electrosurgical instruments for coagulating tissue. More particularly, the present disclosure relates to an articulating, gas-enhanced electrosurgical apparatus for coagulating tissue. 
     BACKGROUND OF RELATED ART 
     Over the last several decades, more and more surgeons are abandoning traditional open methods of gaining access to vital organs and body cavities in favor of endoscopes and endoscopic instruments which access organs through small puncture-like incisions. Endoscopic instruments are inserted into the patient through a cannula, or port, that has been made with a trocar. Typical sizes for cannulas range from three millimeters to twelve millimeters. Smaller cannulas are usually preferred, and this presents a design challenge to instrument manufacturers who must find ways to make surgical instruments that fit through the cannulas and operate in a safe and effective manner. 
     Endoscopic instruments for arresting blood loss and coagulating tissue are well known in the art. For example, several prior art instruments employ thermic coagulation (heated probes) to arrest bleeding. However, due to space limitations surgeons can have difficulty manipulating the instrument to coagulate, desiccate, fulgurate and/or cut tissue. Moreover, if the probe comes into close contact with the tissue, the probe may adhere to the eschar during probe removal possibly causing repeat bleeding. Other instruments direct high frequency electric current through the tissue to stop the bleeding. Again, eschar adherence may also be a problem with these instruments. In both types of instruments, the depth of the coagulation is difficult to control. 
     U.S. Pat. No. 5,207,675 to Canady attempts to resolve certain of the above-noted problems with respect to the prior art by providing a tube-like coagulation instrument in which an ionizable gas is forced through the instrument and ionized by an electrode prior to the gas exiting the distal end of the instrument towards the bleeding tissue. 
     U.S. Pat. No. 5,720,745 to Farin et al. discloses a coagulation instrument which extends through a working channel of an endoscope and includes an electrode for ionizing a stream of ionizable gas exiting the distal end of the instrument at a rate of less than about 1 liter/minute. As explained in detail in the Farin et al. specification, the purpose of discharging the gas at a very low flow rate is to effectively cloud the tissue area and create an ionizable gas “atmosphere” to gently coagulate the tissue. 
     Using these instruments to treat certain more tubular sites, e.g., the esophagus and/or colon, is often difficult, impractical and time consuming. For example, these longitudinally oriented instruments fire the ionized gas and the RF energy in an axial direction from their respective distal ends which, in the case of tubular tissue, would be parallel to the bleeding tissue. Thus, manipulating these instruments to focus the energy transversely or off-axis at the bleeding tissue may be very difficult. 
     Thus, a need exists for the development of a new and effective instrument for treating certain more tubular tissue. 
     SUMMARY 
     The present disclosure relates to an electrosurgical apparatus for coagulating tissue which includes an elongated flexible tube having a proximal end and a distal end and defining a longitudinal axis. The distal end of the tube is movable from a first position wherein the distal end is disposed in a generally rectilinear fashion relative to the tissue to a second position wherein the distal end of the tube directs pressurized ionizable gas flowing through the tube at an angle ∀ with respect to the longitudinal axis. The electrosurgical apparatus also includes at least one electrode mounted proximal to the sleeve for ionizing pressurized ionizable gas. 
     In another embodiment, the electrosurgical apparatus includes a hollow sleeve made from a shape memory alloy, e.g., Nitinol and/or Tinel, which has a generally curved austenite state and displays stress-induced martensite behavior at normal body temperatures. The hollow sleeve is restrained in a deformed stress-induced martensite configuration within the tube wherein partial extension of a portion of the hollow sleeve from the tube transforms the portion from the deformed configuration to its generally curved austenite configuration such that the portion directs the gas transversely at the tissue. The surgical apparatus also includes at least one active electrode for ionizing the gas prior to the gas exiting the portion of the sleeve. 
     Preferably, the angle at which the gas is directed at the tissue is directly related to the distance the portion of the sleeve extends from the tube. 
     In another embodiment of the present disclosure, the electrosurgical apparatus includes a wire connected to the distal end of the tube. The wire is movable from a first generally relaxed position wherein the tube is disposed in a generally rectilinear fashion relative to the tissue to a second retracted position wherein the distal end of the tube flexes at an angle ∀ to direct the gas towards the tissue. Preferably, the angle at which the gas is directed at the tissue is directly related to the amount of tension placed on the wire. 
     Another embodiment includes a corona electrode disposed proximate the distal end of the tube for inducing ignition of the gas prior to emission. A wire is used to articulate the distal end of the tube and direct the gas at the tissue. Preferably, the wire is connected to the corona electrode and electrically connects the corona electrode to a source of electrosurgical energy. A dielectric material is preferably disposed between the corona electrode and the active electrode to prevent arcing between electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front, perspective view of an electrosurgical instrument shown extending through a working channel of an endoscope; 
         FIG. 2A  is an enlarged, side sectional view of one embodiment of the present disclosure showing a hollow shape memory sleeve in retracted position within a catheter; 
         FIG. 2B  is an enlarged view of the hollow shape memory sleeve shown in austenite configuration; 
         FIG. 3  is an enlarged, side sectional view of the shape memory sleeve of  FIGS. 2A and 2B  shown extending and articulating from the catheter to direct ionized gas at the tissue; 
         FIG. 4  is an enlarged, side sectional view of another embodiment of the present disclosure showing a pull wire/return electrode affixed at the distal end of a flexible catheter; 
         FIG. 5  is an enlarged, side sectional view of the embodiment of  FIG. 4  showing the wire being drawn to articulate the flexible catheter and direct ionized gas at the tissue; 
         FIG. 6  is an enlarged, side sectional view of another embodiment of the present disclosure showing a ring corona electrode and a dielectric sleeve seated within a flexible catheter and a pull wire/return electrode affixed at the distal end of the flexible catheter; 
         FIG. 7  is a cross sectional view of the  FIG. 6  embodiment taken along line  7 - 7 ; and 
         FIG. 8  is an enlarged, side sectional view of the embodiment of  FIG. 6  showing the pull wire/return electrode being drawn to articulate the flexible catheter and direct ionized gas at the tissue. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , an articulating tissue coagulator generally identified by reference numeral  10  is shown extending through a working channel of an endoscope  12 . Preferably, the coagulator  10  can be employed with a variety of different endoscopes such as those manufactured by Olympus, Pentax and Fujinon. As such, only the basic operating features of the endoscope  12  which work in combination with the present disclosure need to be described herein. For example, endoscope  12  includes a handpiece  26  having a proximal end  27  and a distal end  29 . In the drawings and in the description which follows, the term “proximal”, as is traditional, will refer to the end of the apparatus which is closer to the user, while the term “distal” will refer to the end which is further from the user. 
     Preferably, the proximal end of the coagulator  10  is mechanically coupled to a supply  18  of pressurized ionizable gas, e.g., inert gas, by way of hose  20  and electrically coupled to an electrosurgical generator  22  by way of cable  24  to supply a source of electrosurgical energy, e.g., high frequency coagulation current. It is envisioned that the electrosurgical generator  22  selectively controls the amount of electrosurgical energy transmitted to an electrode during a surgical procedure. It is also envisioned that the supply of pressurized ionizable gas selectively controls the rate of flow of gas. 
     As shown in  FIG. 1 , a long, flexible tubular member  13  having one or more of working channels  14  located therein is mechanically coupled to the distal end  29  of the handpiece  26 . Preferably, at least one of the working channels  14  is sufficiently dimensioned to receive the coagulator  10  of the present disclosure. Other working channels  14  can be utilized to receive other surgical instruments and accessories such as graspers and biopsy forceps. 
     Turning now to  FIGS. 2A ,  2 B and  3 , one preferred embodiment of the coagulator  10  is shown therein and includes an elongated, generally flexible catheter or tube  30  having a proximal end  32  which extends through a working channel  14  of the endoscope  12  and a distal end  34  which projects outwardly from the distal end  15  of tube  13 . Ionizable gas  28 , e.g., argon, is supplied to the proximal end  32  of the coagulator  10  by a gas conduit (not shown) located inside tube  13 . Preferably, gas  28  is supplied from source  18  to the coagulator  10  at a selectable, predetermined flow rate and flows generally within the tube  30  in the direction of the arrow towards the distal end  34  of tube  30 . Advantageously, the flow rate of the gas  28  is selectively adjustable and can easily be regulated depending upon a particular purpose or a particular surgical condition. 
     Electrode  48  discharges an electrosurgical current, e.g., radiofrequency (RF), which ionizes the gas  28  prior to the gas  28  being directed at tissue  50 . Electrode  48  is connected by way of an electrical conduit (not shown) disposed within tubes  30  and  13  which is ultimately connected to electrosurgical generator  22 . Preferably, the electrode  48  is ring or pin-type and is spaced from the distal end  34  such that the electrode  48  cannot come into contact with the tissue  50  during the surgical procedure. A return electrode or pad  17  is positioned on the patient and is electrically coupled to the electrosurgical generator  22  to lessen the chances of unintentional charring of the tissue  50 . 
     Preferably, a stream of “gas plasma”  46  conducts the current to the tissue  50  while effectively scattering blood away from the treatment site allowing the tissue  50  to readily coagulate and arrest bleeding. A gas plasma  46  is an ionized gas that is used in surgical procedures to conduct electrosurgical energy to a patient by providing a pathway of low electrical resistance. The electrosurgical energy will follow this path and can therefore be used to cut, coagulate, desiccate, or fulgurate blood or tissue  50  of the patient. One of the advantages of this procedure is that no physical contact is required between an electrode  48  and the tissue  50  being treated. One advantage of having a directed flow of gas  28  is that the plasma arc can be accurately focused and directed by the flow. 
     As best seen in  FIGS. 2A ,  2 B and  3 , one approach for manipulating and/or directing the plasma/ionized gas  46  emitting from the distal end  34  of the tube  30  is to implant a hollow sleeve  40  having shape memory characteristics within the distal end  34  of the tube  30 . Preferably, as the sleeve  40  is extended from the distal end  34  of the tube  30 , the sleeve  40  flexes and directs the ionized gas  46  towards the tissue  50 . 
     More particularly, shape memory alloys (SMAs) are a family of alloys having anthropomorphic qualities of memory and trainability and are particularly well suited for use with medical instruments. SMAs have been applied to such items as actuators for control systems, steerable catheters and clamps. One of the most common SMAs is Nitinol which can retain shape memories for two different physical configurations and changes shape as a function of temperature. Recently, other SMAs have been developed based on copper, zinc and aluminum and have similar shape memory retaining features. 
     SMAs undergo a crystalline phase transition upon applied temperature and/or stress variations. A particularly useful attribute of SMAs is that after it is deformed by temperature/stress, it can completely recover its original shape on being returned to the original temperature. The ability of an alloy to possess shape memory is a result of the fact that the alloy undergoes a reversible transformation from an austenite state to a martensite state with a change in temperature (or stress-induced condition). This transformation is referred to as a thermoelastic martensite transformation. 
     Under normal conditions, the thermoelastic martensite transformation occurs over a temperature range which varies with the composition of the alloy, itself, and the type of thermal-mechanical processing by which it was manufactured. In other words, the temperature at which a shape is “memorized” by an SMA is a function of the temperature at which the martensite and austenite crystals form in that particular alloy. For example, Nitinol alloys can be fabricated so that the shape memory effect will occur over a wide range of temperatures, e.g., −2700° to −1000° Celsius. 
     Many SMAs are also known to display stress-induced martensite (SIM) which occurs when the alloy is deformed from its original austenite state to a martensite state by subjecting the alloy to a stress condition. For example and with respect to  FIGS. 2A ,  2 B and  3  of the present disclosure, hollow sleeve  40  is generally bent or L-shaped when disposed in its original or austenite state (see  FIG. 2B ). When sleeve  40  is inserted into the tube  30 , sleeve  40  is deformed, i.e., straightened, into a stress-induced martensite state enabling the user to more easily navigate the tube  30  through tight body cavities and passageways to access damaged tissue  50 . 
     As seen best in  FIG. 3 , after insertion of the tube  30  into the body cavity/passageway, the user can easily direct the ionized gas  46  flowing through the tube  30  transversely (off-axis) at the tissue  50  by extending the sleeve  40  distally which causes the extended portion of the sleeve  40  to revert back to its original/austenite state (it is assumed that the temperature of use of the alloy allows spontaneous reversion when stress is removed). The user can also control the angle α of the ionized gas  46  being directed at the tissue  50  by controlling the distance “X” that the sleeve  40  extends from the tube  30 . Preferably, angle α and distance “X” are directly related, i.e., as distance “X” increases angle α increases. 
     It is envisioned that by empowering the user to articulate, i.e., bend, the distal end  41  of the sleeve  40  at various angles a will enable the operator to more effectively coagulate bleeding tissue  50  with more longitudinal-type lesions, i.e., tissue lesions which run parallel to the axial direction of endoscope  12 , and without causing collateral tissue damage. It is also envisioned that by adjusting the angle α of the distal end  41  of the sleeve  40 , the angle with respect to the tissue surface or longitudinal axis of the tube at which the ionized gas  46  impinges can be selectively controlled. 
       FIGS. 4 and 5  show another embodiment of an articulating coagulator  110  which includes an elongated tube  130  having a proximal end  132  and a distal end  134 . Preferably, tube  130  is flexible at or proximate the distal end  134  of tube  130 . Ionizable gas  28  is supplied to the proximal end  132  of the coagulator  110  at a selectable, predetermined flow rate and flows generally within the tube  130  in the direction of the arrow towards the distal end  134  of tube  130 . Advantageously, the flow rate of the gas  28  is selectively adjustable and can easily be regulated depending upon a particular purpose or a particular surgical condition. Much in the same manner as described with respect to  FIGS. 2A ,  2 B and  3 , electrode  48  discharges an electrosurgical current which ionizes gas  28  prior to gas  28  emission. 
     Coagulator  110  also includes a pull wire  160  which is connected at one end proximate the distal end  134  of tube  130  such that retraction of wire  160  flexes tube  130 . Preferably, wire  160  is disposed within the proximal end  132  of tube  130  and exits a port  136  disposed within tube  130  to attach to tube  130  at a point proximate distal end  134 . Wire  160  is movable from a first generally relaxed position wherein tube  30  is disposed in a generally rectilinear fashion relative to tissue  50  (see  FIG. 4 ) to a second retracted or tensed position wherein the distal end  134  of tube  130  flexes towards tissue  50  (see  FIG. 5 ). The user can easily direct the ionized gas  46  flowing through the tube  130  transversely at tissue  50  by controlling the tensile force applied to wire  160  which, in turn, flexes the distal end  134  of tube  130  to a desired angle α. Empowering the user to articulate, i.e., flex, the distal end  134  of the tube  130  at various angles α will enable the operator to more effectively coagulate bleeding tissue  50  without causing collateral tissue damage. 
     In some cases it may be preferable to utilize wire  160  as a return electrode and couple wire  160  to electrosurgical generator  22 . In this case, the portion of wire  160  disposed within tube  130  is preferably insulated to avoid unintentional ignition and ionization of gas  28 . 
       FIGS. 6-8  show another embodiment which includes an articulating coagulator  210  having an elongated tube  230  with proximal and distal ends  232  and  234 , respectively. Preferably, tube  230  is flexible at or proximate the distal end  234 . Coagulator  210  contains many of the same components and features of the  FIGS. 4 and 5  embodiment with the exception that a “corona ring” electrode is located at the distal end  234  of tube  230  and is used to initiate ionization of gas  28 . 
     A “corona” is a type of discharge which forms around an active electrode to increase the reliability of plasma ignition. Coronas are low current discharges and consume very little power and, therefore, do not affect the overall power delivered to the tissue. Coronas typically occur in highly non-uniform electric fields which are commonly generated between electrodes of greatly differing sizes. 
     A corona electrode is typically located proximate the active electrode  48  and is electrically connected to the return potential of the electrosurgical generator  22 . For example and with respect to the  FIG. 6  embodiment, a ring corona electrode  275  is disposed at the distal end  234  of tube  230  in co-axial alignment with the active electrode  48 . 
     As seen best in  FIG. 7 , a dielectric or insulating sleeve  270  is disposed between the corona electrode  275  and active electrode  48  to prevent arcing between electrodes  275  and  48 . The dielectric sleeve may also prevent arcing between ionizable gas  28  and corona electrode  275 . Preferably, dielectric sleeve  270  is made from a ceramic material or other high temperature resistant material. 
     When the electrosurgical generator  22  is activated, a non-uniform electric field is generated between corona electrode  275  and active electrode  48  and a corona forms around active electrode  48  which aids in igniting gas  28  to produce gas plasma  46 . 
     As mentioned above, coagulator  210  also includes a wire  260  which is connected at one end proximate the distal end  234  of tube  230  such that retraction of the wire  260  flexes tube  230 . Preferably, wire  260  is also connected to corona electrode  275  and performs a dual function: 1) to electrical connect corona electrode  275  to electrosurgical generator  22 ; and 2) to empower the user with the ability to selectively articulate the distal end  234  of tube  230  at varying angles a to effectively coagulate bleeding tissue  50  in a manner similar to the manner described with respect to the  FIG. 4  embodiment. 
     More particularly and as best seen in  FIG. 8 , the user can easily direct gas plasma  46  exiting tube  230  transversely at tissue  50  by controlling the tensile force applied to wire  260  which, in turn, articulates distal end  234  to a desired angle α and enables the user to more effectively coagulate or arrest bleeding tissue  50  without causing collateral tissue damage. 
     From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that not only can the coagulator  10 ,  110  and  210  of the present disclosure be used to arrest bleeding tissue, but the present disclosure can also be employed for desiccating the surface tissue, eradicating cysts, forming eschars on tumors or thermically marking tissue. Those skilled in the art will also appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the present disclosure. 
     In some cases it may be preferable to use various combinations of the component parts shown with respect to each of the embodiments described herein. For example, it may be preferable to combine a SMA (or a stress-induced martensite) with a wire to articulate the distal end of the tube. In another case it may be preferable to use a ring-like corona return electrode with an SMA to induce plasma ignition. 
     In some cases it may be preferable to employ an electrode control mechanism to allow a user to selectively adjust the amount of current flowing through the electrodes during surgical conditions. Moreover, even though it may be preferable to use argon as the ionizable gas for promulgating coagulation of the tissue, in some cases it may be preferably to use another ionizable gas to effect the same or different result. 
     There have been described and illustrated herein several embodiments of a coagulator for arresting bleeding and performing other surgical procedures. While particular embodiments of the disclosure have been described, 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 exemplications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.