Abstract:
A device for coagulating body tissue contains an electrode arrangement comprising a first electrode group and a second electrode group, both of which have strip-shaped electrodes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/808,518, filed Jan. 4, 2013, which is a U.S. National Phase under 35 USC 371 of PCT Application No. PCT/EP2011/003341 filed Jul. 5, 2011, which claims priority to the German Application No. 10 2010 026 210.2, filed Jul. 6, 2010, the disclosures of which are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to an electrode arrangement for coagulating body tissue and/or body vessels. 
       BACKGROUND OF THE INVENTION 
       [0003]    In radio-frequency technology, an electrical radio-frequency field is applied to an electrode to heat and/or shrink tissue by a coagulation current. The radio-frequency voltage is usually applied to an electrode arrangement which is arranged on an inflatable balloon and which then results in a coagulation current via the body tissue. 
         [0004]    An endoscope apparatus for coagulating body tissue is known from U.S. Pat. No. 6,904,303 B2 which has a balloon inflatable by a liquid and comprising a thermally conductive material and has an electrode inside the balloon for heating the liquid. The heat of the heated liquid is transmitted via the balloon to the body tissue to be treated. In another embodiment, the heated electrically conductive liquid as a conductor for radio frequency energy is transferred outwardly to the tissue through porous openings of the balloon. 
         [0005]    An endoscope for coagulating body tissue is known from US 2007/028 7994 A1 in which a balloon is provided at the end which can be inflated by a liquid and which has a plurality of electrodes at the outside which are arranged lengthways and via which radio frequency energy is transmitted to the body tissue for bipolar treatment. 
         [0006]    The body tissue is heated homogeneously in contact with the electrodes. This results in an areal coagulation. With non-homogeneously distributed or irregularly arranged electrode arrangements, the liquid is heated irregularly and non-homogeneously in the balloon. The upper portion of the balloon becomes hotter on a longer-lasting heating due to convection of the liquid in the balloon so that a non-homogeneous heat distribution in and around the balloon results. 
         [0007]    Another known electrode arrangement for coagulating body cavities, e.g. a uterine cavity, has rigid preshaped electrodes. A further known electrode arrangement is used for coagulating bleeding gastrointestinal ulcers, with here small tips being used which are arranged over balloon catheters. 
         [0008]    The positioning of a balloon in a small body cavity is difficult since it cannot be done in view. Thrombi occur around the balloon which provide non-reproducible conditions for the use of electrical fields or for radio frequency ablation (tissue denaturation), and indeed in comparison with the positioning of a defined balloon directly on the tissue to be treated. 
         [0009]    Medical instruments, in particular rigid endoscopes, for the resection of tissue are known. Different endoscopic resection instruments are thus described in chapter 1 of the text book “Endoskopische Urologie” [Endoscopic Urology] by Prof. Dr. R. Hofmann, 2nd Edition, 209, Springer Verlag. Such a known resectoscope is shown in  FIG. 1 . This known resectoscope comprises an instrument shaft  1 , an endoscope optics  2  with a connector for a light cable  3  and a working element. The instrument shaft  1  usually has 24 charr. or 24 charr. circumference. The instrument shaft  1  can be used for continuous rinsing, i.e. a separate rinsing water inflow  4  and a sucking out  5  of the irrigation liquid (rinsing liquid) takes place. The water inflow is regulated by a faucet  6 . Only the inflow of irrigation liquid can also take place which is let off with a full bladder by removing the working element from the instrument shaft  1 . 
         [0010]    The working element comprises a handle  7  for the third and fourth fingers. This handle  7  is fixedly attached to the instrument shaft  1  at a receiving tube  8  for the optics  2  and at a locking mechanism of the working element formed as a rotary closure. A moving restoring element  9  for the thumb grip is attached to the handle  7 . A “passive resection instrument” is spoken of when a surgical noose formed as a surgical element is introduced into the instrument shaft  1  by the spring balance and is moved out against spring resistance. The working element moves passively back into the starting position again by spring force. An active working element is present when the surgical noose is moved out by the spring force in the relaxed state and a carriage  10  has to be retracted against the spring force using the thumb grip  9 . 
         [0011]    The movable carriage  10  is fastened to the thumb grip  9  and slides over the receiving tube  8  for the optics  2 . It is usually an element which is made of plastic and which has an electrical feed line  11  as well as a button  12  for locking the electrode rod. 
       SUMMARY OF THE INVENTION 
       [0012]    During endoscopic surgery, e.g. on a transurethral resection of a benign or also malignant prostate growth (TURP), tissue can be resected using a special cutting current from a radio frequency voltage generator either with a previously customary electrode arrangement or with a bipolar electrode arrangement. With the monopolar electrode arrangement, the current flows from an active electrode through a hypotonic, less conductive solution (e.g. a glycine solution, mannitol solution) through the body of the patient to a large areal neutral electrode. Two electrodes are located close to one another in the bipolar electrode arrangement. The current flows through a very conductive solution such as a saline solution from the one to the other electrode. 
         [0013]    Bleeding regularly occurs during a TURP. Arterial and venous bleeding can now be directly atrophied in view by a coagulation current using the resection noose supplied with the radio frequency voltage. A spherical cavity is formed at the end of the TURP. Arterial bleeding has to be directly coagulated. With small arteries, a sintering of arterial bleeding is achieved by pressure using a balloon catheter. Diffuse venous bleeding from the whole resection area is usually present with a reduced or terminated rinsing flow at the end of the operation and it is only sintered by insertion of a balloon catheter. 
         [0014]    A balloon can either be unfolded in the prostate cavity and then directly results in the compression of the venous bleeding or it is e.g. unfolded in the bladder located adjacent to the prostate cavity and is then pulled back to the prostate cavity so that hemostasis is achieved by compression of the prostate cavity. 
         [0015]    The transurethral catheter usually has to be rinsed for some days and left to avoid a bladder tamponade. A substantial morbidity hereby arises for the patient such as pain in the urethra and in the bladder. Strangury, discharge from the urethra next to the catheter or urinary tract infections with fever occur. Protracted blood loss from the large wound area of the prostate cavity, due to the surgical procedure, or arterial bleeding, or more frequently venous bleeding, caused by friction and injury to the coagulation surface of the prostate cavity by the balloon are not rare. 
         [0016]    In 2% to 5% of operations, postoperative urethral strictures occur after the TURP, with the longer indwelling time of an insert of a catheter in the urethra and an infection caused thereby being considered risk factors. The catheter frequently also clogs with blood thrombi if the continuous rinsing catheter is not regularly rinsed. The blood clots which form in this respect then have to be rinsed out of the catheter using bladder syringes. The catheter must also occasionally have to be replaced or a bladder tamponade has to be surgically excised under anesthetic. 
         [0017]    A similar situation is present in suprapubic adenomectomy (removal of the prostate through the abdominal wall). Here, the large benign gland is enucleated by the surgeon either through the capsule of the prostate or transvesically (through the bladder) by the finger so that a large cavity arises. Diffuse venous bleeding usually remains which is stopped by transurethral insertion of a balloon catheter which is unfolded with pressure in the cavity. However, considerable complaints hereby arise for the patient for some days up to the catheter removal such as pain, foreign-body sensation in the rectum and in the urethra or bladder as well as stranguries due to the foreign body irritation. 
         [0018]    It is therefore the object of the invention to provide an electrode arrangement of the initially named kind for coagulating body tissue and/or body vessels, wherein the coagulation can take place more simply, more effectively and faster for avoiding the named disadvantages of the known devices. 
         [0019]    This object is satisfied by the features of claim  1 . The ribbon-like electrode pairs can be brought to the positions to be treated simply and fast in their relaxed position. They can also be expanded in dependence on the available space of the body tissue and/or of the body vessels simultaneously and fast in touching contact with the body tissue and/or the body vessels. The correspondingly widely expanded electrode pairs then contact a large area at a desired pressure. A radio frequency control voltage of the radio frequency control voltage generator connected to all electrode pairs then generates a bipolar coagulation current simultaneously and over a large area in the body tissue. The coagulation effect is hereby amplified and the coagulation time shortened. 
         [0020]    The electrode arrangement can be introduced through all commercial resection shafts in the relaxed state and can then be unfolded in endoscopic view and positioned in the prostate cavity. In the expanded state the electrode rows are expanded like meridians of a balloon. A coagulation flow respectively flows simultaneously between the two star-shaped electrode rows and effects an areal bipolar coagulation so that the venous bleeding or smaller arterial bleeding is stopped. The catheter indwelling time is shortened by a bleeding-free cavity at the end of surgery. The insertion of a transurethral catheter can therefore be dispensed with. 
         [0021]    The coagulation takes place using a radio frequency control voltage generator suitable for radio frequency surgery. The control voltage has a frequency of approximately 900 to 600 kHz. The output power of the radio frequency control voltage generator amounts to at least 300 W. The coagulation takes place slowly so that no fast carbonization of the tissue takes place. It is advantageous if the radio frequency control voltage generator is adapted as a regulated generator to the impedance of the system with the two electrode groups and the body tissue. The SWR (standing wave ratio) can be measured before the coagulation process and can be fixed as the starting value. During the coagulation process, the impedance is then measured constantly and is kept in a previously defined range. The impedance of the system lies approximately between 10 and 15 ohms. The SWR increases during the coagulation. An exceeding of the upper limit value results in the switching off of the system. The operation time for the radio frequency control voltage generator is fixed by the surgeon. The SWR monitoring can, however, result in a premature automatic switching off. 
         [0022]    The arrangement can be used in a similar manner for suprapbubic (by surgery from the abdominal wall) use, with now a handle with a sliding mechanism for folding and unfolding or expanding and relaxing the electrode arrangement, a locking arrangement for the electrode rod and a plug-in connection for the electrode cable becoming necessary. 
         [0023]    Further advantageous embodiments of the invention result from the dependent claims. 
         [0024]    The ribbon-like electrode pairs of the electrode arrangement can thus be expanded like meridians of a balloon. 
         [0025]    If an operation is carried out by means of a surgical element, e.g. a resection noose, an endoscope introduced through an instrument shaft, this surgical element is removed after surgery and the electrode arrangement is introduced through the instrument shaft in its place without this instrument shaft having to be removed. It remains in the body. The time up to the start of the areal coagulation and the time for the coagulation itself are substantially shortened by this measure and by the simple and fast expanding of the electrode arrangement. 
         [0026]    In particular the whole surgical instrument with the resection loop can thus in particular be swapped at the end of an operation. A coagulation apparatus with a relaxed electrode arrangement can then be introduced as a second working element into the resection shaft for the areal coagulation. A receiving tube for an endoscope optics is somewhat shorter than a usually utilized receiving tube which otherwise extends up to the end of the shaft. The receiving tube can be shortened so much that it ends shortly after a bayonet closure for the latching of the stabilization tube. The relaxed electrode arrangement can hereby also be introduced through small shaft diameters (e.g. 22 charr. or less). The coagulation apparatus is first introduced with the relaxed electrode arrangement through the instrument shaft and is latched with the shaft. It is thereby achieved that the electrode arrangement projects out of the shaft. Subsequently, the endoscope optics is introduced through the reception tube and the electrode arrangement is then expanded in view e.g. in the prostate cavity. The removal of the electrode arrangement takes place in reverse order, i.e. the electrode arrangement is first relaxed, then the endoscope optics is removed and subsequently the coagulation apparatus with the relaxed electrode arrangement is pulled out through the instrument shaft. 
         [0027]    The electrode arrangement formed as an electrode rod can have an insulated infeed, a capillary draw tube and a hose sheath and can slide through a stabilization tube fixed to a receiving tube for the endoscope optics. A carriage can be moved actively or passively by moving to and fro, e.g. with the thumb, in a similar manner to a resection electrode. The first and second electrode groups can hereby be expanded, with the envelopes of the first and second electrode groups being axially displaced with respect to one another. The electrodes of these two electrode arrangements also have the same configuration in the expanded state. 
         [0028]    In a first axial region, the envelope of the first electrode group lies within the envelope of the second electrode group. In an adjoining axial region, in contrast, the envelope of the first electrode group lies outside the envelope of the second electrode group. The electrode arrangement is positioned in the prostate cavity in view to avoid the electrodes of the electrode arrangement being incorrectly positioned. The electrode arrangement can hereby be ideally unfolded into the prostate cavity. The formation of thrombi during the areal coagulation is avoided by the simultaneous slow rinsing inflow. The electrodes firmly contact the tissue and adapt to irregularities due to their flexible design. The coagulation takes place in a saline solution between the respective adjacent electrodes of the first and second electrode groups which are held at the same spacing from one another in the expanded state. 
         [0029]    An advantage of this electrode arrangement is that the electrode arrangement can be introduced through all commercial resection shafts in the relaxed state and can be positioned in endoscopic view e.g. in a prostate cavity, and can be expanded there. With the bipolar coagulation current between the individual expanded electrode pairs, a large-area coagulation is carried out by which a venous bleeding or smaller arterial bleeding can be stopped fast. The catheter indwelling time is shorted by a bleeding-free cavity at the end of surgery. An insertion of a transurethral catheter can be dispensed with. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The invention will be described in the following with respect to the embodiments shown in  FIGS. 1 to 10 . There are shown: 
           [0031]      FIG. 1  a prior art resectoscope that has an instrument shaft, endoscope optics with a connector for a light cable, and a working element; 
           [0032]      FIG. 2  a schematic representation of an apparatus in accordance with the invention with an electrode arrangement expanded like meridians of a balloon; 
           [0033]      FIG. 3  the design of an electrode star of the first and second electrode groups; 
           [0034]      FIG. 4  a detail of the central region (distal end) of the electrode star in accordance with  FIG. 3 ; 
           [0035]      FIG. 5  an oppositely disposed end (proximal end) of a ribbon-shaped electrode of the electrode start in accordance with  FIG. 3 ; 
           [0036]      FIG. 6  a spatial representation of the electrode arrangement expanded like meridians of a balloon; 
           [0037]      FIG. 7  a detail of the representation of  FIG. 6 ; 
           [0038]      FIG. 8  an anode and cathode coupling at the distal end of the electrode arrangement with insulation plate; 
           [0039]      FIG. 9  a coupling plate with an insulating plate at the proximal end of the electrode arrangement; and 
           [0040]      FIG. 10  an electrode rod in section. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    In accordance with  FIG. 2 , a resectoscope includes an instrument shaft  20  and an endoscope optics  21  having a connector  22  for a light cable. A receiving tube  23  for the optics leads into an instrument housing  24 . A movable carriage  25  is connected to a grip  26  actuable by a thumb. A handle for the third and fourth fingers is designated by  27 . A radio frequency generator  29  which delivers a radio frequency coagulation voltage to an electrode arrangement in a manner not shown is connected to an anode connector and cathode connector  28 . This electrode arrangement includes a first and second electrode group  31  and  32  which are insulated with respect to one another and which each form bipolar electrode pairs. The electrode pairs of the first and second electrode groups  31  and  32  are expanded in  FIG. 2  like meridians of a balloon by a capillary draw tube  33   a  ( FIG. 10 ) and an electrode rod  33  ( FIG. 10 ), with the electrodes of the one electrode group  31  and of the other electrode group  32  alternating in the peripheral direction. 
         [0042]    The endoscope optics  21  is first pulled out of the instrument shaft  20  to the left in a manner not shown with respect to  FIG. 2  after an endoscopic operation. The surgical instrument, not shown, is subsequently removed through the instrument shaft  20  and is then replaced with the electrode rod  33  with electrode arrangement  30  which is likewise introduced from the left hand side, with in this respect the electrode groups  31  and  32  of the electrode arrangement  30  being relaxed and contacting the capillary draw tube  33   a  of the electrode rod  33 . The endoscope optics  21  is then introduced again. 
         [0043]    In  FIG. 3 , an electrode star  34  of the electrode group  31  is shown in the unwound (not installed) state. The individual electrodes or electrode arms  31   a ,  31   b ,  31   c ,  31   d ,  31   e  and  31   f  are in ribbon shape and flexible and are electrically conductive. In the embodiment shown, six electrodes  31   a - 31   f  are arranged in star shape and are connected to one another in one piece at a central region. The central region in accordance with  FIG. 4  has a central opening  35  for an electric infeed  50  ( FIG. 10 ). The outer ends  36   a - 36   f  of the electrode star  34  in  FIG. 3 , which are shown enlarged in  FIG. 5 , have openings to allow a passage of the capillary draw tube  33   a  of the electrode rod  33 . The individual electrode arms, which are elastically deformable, are narrower towards their respective ends, as can in particular be seen from  FIGS. 4 and 5 , i.e. they have end sections with a reduced width. The coagulation effect is hereby reduced in this region. 
         [0044]    Alternatively to this or also to optimize the reduction of the coagulation effect, the respective end regions can, in accordance with a further embodiment, be provided with insulation which extends, for example, over approximately the last 5-10 mm. It is hereby avoided that e.g. the apical (lower) region of the prostate with the sphincter disposed thereunder as well as the portion of the tissue extending into the bladder are heated too much on a coagulation. 
         [0045]    The electrode arrangement  30  is shown in the expanded state in  FIG. 6 . The electrodes  31   a - 31   f  form the first electrode group  31 , whereas electrodes  32   a - 32   f  form the second electrode group  32 . The capillary draw tube  33   a  of the electrode rod  33  allows the axial displacement of the distal ends of the first and second electrode groups  31  and  32  into the position expanded to form the balloon. All the outer end regions  36   a - 36   f  or  36   a ′ to  36   f ′ of the individual electrodes  31   a - 31   f  and  32   a  to  32   f  are each provided with an insulating layer. 
         [0046]    As in particular  FIGS. 6 and 7  show, the first electrode group  31  is arranged axially rotated with respect to the second electrode group  32  in a manner such that the ribbon-shaped electrode arms  31   a - 31   f  of the first electrode group  31  each extend between the ribbon-shaped electrode arms  32   a - 32   f  of the second electrode group  32  and each form bipolar electrode pairs. 
         [0047]    In a first (distal) region, the envelope of the first electrode group  31  lies within the envelope of the second electrode group  32 . In an adjoining (proximal) axial region, in contrast, the envelope of the first electrode group  31  lies outside the envelope of the second electrode group  32 , i.e. the two envelopes intersect (cf. also  FIG. 2 ). 
         [0048]    In  FIG. 7 , a detail of the proximal end region of the two electrode groups  31  and  32  is shown. The electrodes  31   a - 31   f  of the first electrode group  31  are arranged rotated about the center axis in the peripheral direction with respect to the electrodes  32   a - 32   f  so that the electrodes  31   a ,  32   a - 31 ,  32   f  each form electrode pairs. A coupling element shown enlarged in  FIG. 9  is designated by  37 . 
         [0049]    In  FIG. 8 , an anode coupling  38  as well as a cathode coupling  39  are shown for the distal ends of the electrodes of the first and second electrode groups  31  and  32 . A plate  40  insulating the two couplings are located between the anode coupling and the cathode coupling (cf. also  FIG. 10 ). 
         [0050]    A coupling sleeve  42  is shown in  FIG. 9  which has two mutually insulated coupling sleeve parts  43  and  44  as well as an insulation  45  located therebetween. This coupling is provided at both sides with securing plates  46  and  47 . In the installed state, the coupling sleeve  42  can slide axially over the electrode rod  33  so that a sliding mechanism can be reached. 
         [0051]    This sliding mechanism is actuated by a movement of the hand as can be seen in  FIG. 2 , e.g. by a thumb movement. A locking screw, not shown, comprising a cylinder screw, a clamping screw and a knurled screw locks the capillary draw tube  33   a  of the electrode rod  33 . The parts of the electrode rod  33  are moved with the aid of a carriage  25 , not shown in any more detail, on a receiving tube  23  of the endoscope optics  21  so that the electrode groups  31  and  32  can thereby be expanded like the meridians of a balloon and can be relaxed again. The locking screw acts as a clamping element in the manner of a movable carriage which effects the coupling of the electrode. 
         [0052]      FIG. 10  shows the electrode rod  33  in detail. It has a concentrically or coaxially arranged structure, with the electrical infeed  50  or the electrode cable which is insulated by an insulation  53 , e.g. by Teflon, being arranged in the interior. The capillary draw tube  33   a  extends over this insulated line, extends up to the front end of the electrodes  31   a - 31   f  and  32   a - 32   f  of the two electrode groups  31  and  32  and is there connected to the coupling unit of  FIG. 8 . 
         [0053]    An insulation hose  51 , which likewise extends up to the front end, is located above the capillary draw tube  33   a . The total arrangement is led through a stabilization tube  52  to whose distal end the coupling sleeve  42  ( FIG. 9 ) is fastened. 
         [0054]    The insulated electrical infeed  50  slides in the interior of the stabilization tube  52  which can be closed or also partly open longitudinally. The sliding mechanism allows the opening or closing or expanding and relaxing of the two electrode groups  31  and  32  by displacing the capillary draw tube  33   a  relative to the stabilization tube  52 . The movement of the electrode rod  33  takes place such that the capillary draw tube  33   a  is fixed to a movable carriage  25  which is moved by the thumb grip of the working element. The capillary draw tube  33   a  which is provided with the insulation hose  51  thus slides in the stabilization tube  52  which is fixed to the receiving tube  8  for the optics  2 . The electrode rod  33  is preferably fixed beneath the receiving tube  8  for the optics. 
         [0055]    The stabilization tube  52  has a locking element, e.g. in the form of a bayonet closure  54 , so that the total arrangement remains fixed to the working element. The receiving tube for the optics in the endoscope is connected by this bayonet closure to the stabilization tube  52  of the electrode rod  33 . 
         [0056]    An electrical plug-in connection for the electrode cable  50  is located at the carriage directly behind the locking element for the capillary draw tube  33   a  of the electrode rod  33 . 
         [0057]    The electrode arrangement is positioned in the prostate cavity in view to avoid the electrodes of the electrode arrangement being incorrectly positioned. The electrode arrangement can hereby be ideally unfolded into the prostate cavity. The formation of thrombi during the areal coagulation is avoided by the simultaneous slow rinsing inflow. The electrodes firmly contact the tissue and adapt to irregularities due to their flexible or elastic design.