referring now to fig1 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 fig1 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 fig2 a , 2b 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 fig2 a , 2b 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 ., − 270 ° to + 100 ° 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 fig2 a , 2b and 3 of the present disclosure , hollow sleeve 40 is generally bent or l - shaped when disposed in its original or austenite state ( see fig2 b ). 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 fig3 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 α 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 . [ 0035 ] fig4 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 fig2 a , 2b 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 fig4 ) to a second retracted or tensed position wherein the distal end 134 of tube 130 flexes towards tissue 50 ( see fig5 ). 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 . fig6 - 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 fig4 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 fig6 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 fig7 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 fig4 embodiment . more particularly and as best seen in fig8 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 .
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 .