Patent Document

BACKGROUND OF THE INVENTION 
   The invention concerns a catheter for intravascular application, with a proximal and a distal end and a catheter longitudinal axis, comprising a shaft extending along the catheter longitudinal axis from the proximal end to the distal end and having a fluid-tight shaft wall and at least one lumen which is adapted to guide a fluid, which extends from the proximal end at least into the proximity of the distal end of the catheter, and which is enclosed by the shaft. The catheter also has at least one electrically conductive wire which extends from the proximal end at least into the proximity of the distal end of the catheter along the catheter longitudinal axis. 
   The state of the art discloses catheters which include wires in the form of control wires for deflecting the distal end of a catheter, or electrical feed lines for electrodes, for example high-frequency lines in the case of ablation catheters or also in the form of electrical feed lines for sensors. The wires, in the form of control wires or electrical feed lines, are usually guided in the interior of a catheter shaft. 
   Those catheters which are known from the state of the art involve the problem that the wires which extend in the catheter shaft, when using the catheter during a magnetic resonance tomography, are significantly heated by high, electromagnetically-induced currents, so that the conduction of heat results in a rise in the temperature of the catheter shaft, which entails the risk of coagulation along the catheter shaft. 
   In the case of ablation catheters, there is equally the risk of coagulation phenomena along the catheter shaft disposed in the body, due to high, high-frequency currents which are passed in the feed lines to the ablation electrode and which result in an increase in the temperature of the feed lines and, by way of heat conduction, an increase in the temperature of the catheter shaft. 
   DE 693 32 414 T2 discloses a cryogenic catheter which has lumens for guiding a coolant and temperature sensors at the distal end for monitoring the temperature of an ablation electrode and the coolant. 
   U.S. No 2003/0004506 and U.S. Pat. No. 5,348,554 disclose catheters having a fluid-cooled ablation electrode. 
   U.S. Pat. No. 5,980,515 discloses a catheter with a rotating saw tool and a flushing device, wherein the flushing device can also serve for cooling an ablation electrode. 
   The problem of catheter shaft heating due to electrically conductive wires extending in the shaft is not referred to in those patent specifications and is also not resolved. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is that of providing a catheter in which the above-described problem of catheter shaft heating due to electrically conductive wires extending in the shaft does not occur, in particular when applying magnetic resonance tomography. 
   That object is attained by a catheter of the kind set forth in the opening part of this specification in which on at least one portion length of the catheter which is provided for introduction into a body, a lower level of heat-transmission resistance obtains between a fluid in the lumen and conductive wire than between the wire and the shaft wall so that heat produced in the wire can be effectively dissipated to the fluid flowing in the lumen. For that purpose the catheter includes a temperature sensor which is arranged to detect a temperature which in the case of heating of the wire depends at least predominantly on the heating of the wire. 
   The temperature sensor can be heat-conductingly connected to the wire. The term “heat-conductingly connected” is used here to denote both transmission of heat by way of atomic vibrations and also transmission of heat by way of mass transport. The heat-conducting connection can thus include both convective conduction and also phonon conduction. 
   The temperature sensor is arranged for example, at a location spaced from the distal end, for directly or indirectly detecting a temperature of the shaft wall, on the basis of heat produced in the wire, on the portion of the shaft which is provided for introduction into a body and at which the shaft wall temperature depends substantially on the wire temperature. 
   For direct detection of the shaft wall temperature, the temperature sensor is arranged on or in the shaft wall. With that arrangement, the risk of forming coagulation phenomena can be derived directly from a shaft wall temperature value. 
   For indirect detection of the shaft wall temperature, the temperature sensor can be arranged on the heat-transmission section from the wire to the shaft wall. 
   For example, the temperature sensor is arranged on the wire or in the wire or is formed by the wire itself. In that arrangement, the shaft wall temperature can be calculated or ascertained empirically. For indirect detection of the shaft wall temperature, the temperature sensor can be arranged in a wire-guiding lumen and can there detect the temperature of a fluid. In that case also, the shaft wall temperature can be calculated or ascertained empirically. 
   In the case of an ablation catheter, the temperature sensor is arranged at a sufficient spacing from an ablation electrode disposed at the distal end of the catheter, in such a way that the heat discharged by the ablation electrode does not influence temperature measurement of the shaft rise in temperature caused by the wires. Therefore, in accordance with the invention, “spaced from the ablation electrode” means arranged to be sufficiently heat-insulated from the ablation electrode. 
   Cooling of the wire by way of the fluid advantageously provides that the discharge of heat from the catheter shaft to the medium surrounding the catheter shaft is reduced. The temperature sensor advantageously makes it possible to monitor the catheter shaft temperature, preferably by an arrangement for detecting the fluid temperature. 
   In a preferred embodiment, the catheter has a first and a second lumen, which are adapted to carry a fluid and which extend from the proximal end of the catheter into the proximity of the distal end thereof and which are enclosed by the shaft. In the region of the distal end, the catheter has a fluid passage between the first lumen and the second lumen so that the fluid can flow in one lumen in the direction of the distal end and from there back to the proximal end in the fluid passage and the second lumen. 
   This embodiment can advantageously implement a closed cooling circuit. 
   In the proximity of the distal end, the catheter can have at least one opening which is in fluid communication with at least one of the lumens and which is so designed that fluid can flow outwardly from the catheter. 
   The embodiment of the catheter with two lumens can have at least one opening at the distal end by way of which the fluid can flow outwardly. In this embodiment, the catheter has a fluid flow guide means formed by the lumens with an outlet at the distal end for cooling of the ablation electrode and/or the tissue surrounding the tissue surrounding the electrode. 
   Alternatively, the catheter can also be embodied with a unidirectional fluid guide means. Such an opening is already known in relation to ablation catheters from the state of the art, the opening in the catheter being arranged in such a way that heat produced at the ablation electrode can be partially dissipated to the fluid. 
   In a further embodiment, the distal end is adapted to feed exclusively a fluid flowing in a second lumen to the ablation electrode. This embodiment advantageously makes it possible to provide for separate cooling effects with respectively different temperature regulation values for wires to be cooled and the ablation electrode. The catheter in this embodiment has three separate lumens. A first lumen is in the form of a wire-guiding lumen, in which wires to be cooled are arranged along the longitudinal axis of the catheter. The temperature sensor in this embodiment is preferably arranged in the wire-guiding lumen or in the proximity thereof, with good thermal contact. In this case, the distal end is adapted to return the fluid used for cooling the wires by way of a third lumen. As an alternative thereto, the distal end is adapted either to cause the fluid used for cooling the ablation electrode to issue from the catheter by way of an opening or also to return it by way of the third lumen. As in that case, both the heat of the ablation electrode and also the heat of the wire is dissipated by way of the fluid flowing in the third lumen, when the temperature sensor is arranged outside the wire-guiding lumen, the level of heat-transmission resistance is greater between the third lumen and the temperature sensor than between the temperature sensor and the wire-guiding lumen. 
   In a further preferred feature, the second lumen and/or further lumens is or are disposed within the first lumen. The lumens can be formed by individual tubes. As an alternative thereto, the lumens can be formed along the longitudinal axis of the catheter by at least one separating wall in a tube and the fluid passage can be formed by at least one aperture. It is also possible to envisage an embodiment which has a combination of lumens separated by separating walls and lumens formed by individual tubes. There are three alternative configurations in regard to embodying the lumens in the interior of the catheter: the lumens can be embodied in mutually juxtaposed relationship, separated from each other by separating walls, in a tube. Alternatively, a plurality of tubes can be arranged in a casing lumen. Those tubes can be arranged in mutually juxtaposed relationship or one within the other (coaxial). 
   In a preferred embodiment, the wire is an electrical feed line. The electrical feed line can be in the form of a single-conductor or multi-conductor feed line, for example, in the form of a feed line for an ablation electrode or a feed line for sensors. 
   The wire can also be a control wire which is arranged in the interior of the lumen in the direction of the catheter longitudinal axis. Such a control wire can be arranged, for example, in a guide wire. Preferably the control wire is adapted to deflect the distal end of a catheter with a directional component transversely with respect to the catheter longitudinal axis. The distal end of the catheter can thereby be curved by way of the control wire and the catheter can thus be guided in curves within a lumen in a body. For that purpose, the control wire is fixed to the distal end of the catheter and is preferably arranged displaceably in the interior of the lumen in the direction of the catheter longitudinal axis. In accordance with the invention, a guide wire can also be of such a configuration, by means of a lumen, that it is to be cooled by means of a fluid. The rise in temperature of such a guide wire can be effected, in the case of magnetic resonance tomography, in that currents are induced in a conventional wire coil or a metal shaft of such a guide wire. Due to a lumen, arranged in the interior of the wire coil, of a guide wire, the latter can be cooled and also represents a catheter in accordance with the invention. The wire, heated by induction, of such a guide wire is thus, by way of example, a metal coil or a metal shaft of the guide wire. 
   In a preferred embodiment, the catheter has at least one temperature sensor for detecting the temperature of the fluid or the wire or the shaft wall. 
   The catheter can also have at least one temperature sensor for detecting the temperature of a fluid issuing at the proximal end of the catheter. 
   A temperature sensor can also be arranged along the catheter longitudinal axis in the region of the center of the catheter shaft portion which is provided for intracorporeal invasion. In the case, for example, of ablation catheters, that affords a sufficient spacing from an ablation electrode and the heat given off thereby. 
   A shaft of a catheter, in accordance with the invention, can have a plurality of temperature sensors arranged along the catheter longitudinal axis. The temperature sensors are arranged to detect the temperature of a wire and/or of the shaft wall and/or a lumen. By way of example, the temperature sensors are formed by a plurality of wires extending in a spiral configuration in the peripheral direction of the catheter shaft or by longitudinal wires extending along the longitudinal axis of the catheter, the wires extending in the spiral configuration and the longitudinal wires being adapted to not substantially heat up in a magnetic field of a magnetic resonance tomograph. For that purpose, the temperature sensors are preferably of a high-resistance nature. 
   In an alternative configuration, the catheter is an ablation catheter. For that purpose, at its distal end, the catheter includes an electrode which is electrically connected to the wire and by way of which a high-frequency electrical current can be delivered to tissue disposed in the area around the electrode. As a result, heat is produced in the tissue, by which the tissue is damaged or destroyed. Accordingly, in particular pathologically altered tissue can be specifically and targetedly destroyed with an ablation catheter in order thereby, for example, to locally block the conduction of cardiac action signals. 
   The catheter can also be a mapping catheter. For that purpose in the region of the distal end the catheter includes one or more sensing electrodes. The catheter can also be a pacemaker or defibrillation electrode. 
   In a preferred embodiment, the catheter is in the form of an ablation and mapping catheter, in which the features of an ablation catheter and those of a mapping catheter are embodied on just one catheter. For that purpose, besides at least one ablation electrode, the catheter includes at least one sensing electrode. 
   The invention also concerns an arrangement for intravascular invasion, including a catheter in accordance with one of the above-indicated embodiments and a fluid feed unit which is in fluid communication with at least one lumen of the catheter and adapted to produce a flow of fluid into the lumen. 
   Preferably, the arrangement also includes a temperature monitoring unit connected to at least one temperature sensor of the catheter. 
   The arrangement may also include a cooling unit which is in fluid communication with at least one lumen of the catheter and adapted to remove heat from a fluid. Preferably, the cooling unit is adapted to remove heat from the fluid in dependence on a cooling control signal. Further advantages are enjoyed if the cooling unit is adapted to alter the thermal power removed from the fluid in dependence on the control signal. For that purpose, the cooling unit may include at least one Peltier element. The arrangement can include a temperature regulating device for observing a predetermined fluid temperature, for example in a cooling circuit. 
   In an advantageous embodiment, the fluid feed unit includes a controllable pump unit which is in fluid communication at least with a lumen of the catheter and adapted to pump a fluid into the lumen in dependence on a fluid control signal. In a further advantageous feature, the pump unit can be adapted to pump a predetermined volume of fluid into the lumen per unit of time in dependence on the fluid control signal. 
   The fluid feed unit can also be formed by an arrangement with a fluid container and a feed conduit, wherein when the fluid container is arranged at a higher level in relation to the catheter, as in the case of an infusion drip, the fluid can flow downwardly into the catheter. 
   In an alternative embodiment, the arrangement has a cooling circuit in which the pump unit and the cooling unit are contained, and a temperature monitoring unit, wherein the temperature monitoring unit is operatively connected to at least one temperature sensor, the pump unit or the cooling unit or both. The temperature sensor is adapted to produce a temperature signal representative of a temperature and the temperature monitoring unit is adapted to evaluate a temperature signal produced by the temperature sensor and to control the pump unit or the cooling unit or both in accordance with a regulating algorithm predetermined in the temperature monitoring unit and to produce control signals corresponding thereto. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows diagrammatically illustrated cross-sections through possible embodiments of a catheter, 
       FIG. 2  diagrammatically shows views in two longitudinal sections of distal ends of ablation catheters, and 
       FIG. 3  diagrammatically illustrates an embodiment of an arrangement with an ablation catheter with cooled wires. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention will now be described in greater detail with reference to Figures. 
     FIG. 1   a  diagrammatically shows a view in cross-section of a catheter  101 . The catheter  101  includes a catheter shaft having a shaft wall  102  and a first lumen  104  which is enclosed by the shaft wall  102 . Disposed in the lumen  104  are wires  106  which can be in the form of electrical feed lines. Disposed in the lumen  104  there is also a second lumen  105  which is enclosed by a second shaft wall  107 . A wire  103  to be cooled is disposed in the second lumen  105 . The shaft walls  102  and  107  are of fluid-tight nature. 
   When using a catheter with such a catheter shaft cross-section, a fluid, for example a cooling fluid, can flow, for example through, the second lumen  105 . 
   The through-flow of fluid can be in the form of a unidirectional flow. For that purpose, in the region of the proximal end, the catheter has an intake for the fluid, while in the region of the distal end it has an outlet for the fluid. 
   The through-flow of fluid can also be in the form of a counter-flow. For that purpose, in the region of the distal end the catheter has a fluid passage (not shown in this Figure) through which the lumens  105  and  104  are in fluid communication in the region of the distal end. The fluid can now flow, for example, in the second lumen  105  in the direction of the distal end and can flow back through the first lumen  104  by way of the fluid passage to the proximal end of the catheter. It is also possible to conceive of a reversed direction of flow so that the fluid flows in the first lumen  104  to the distal end and back in the second lumen  105  to the proximal end. 
     FIG. 1   b  shows a view in cross-section through a catheter shaft  121  with a shaft wall  122  which encloses a first lumen  127  and a second lumen  126 . The first lumen  127  and the second lumen  126  are separated from each other by a separating wall  125 . An electrically conductive wire  123  and electrical feed lines  124  are disposed in the second lumen  126 . The shaft wall  122  and the separating wall  125  are of a fluid-tight nature. 
   By way of example, a fluid can flow in the second lumen to the distal end of the catheter, it can be passed in the region of the distal end through a fluid passage (not shown) into the first lumen  127  and there it can flow back to the proximal end of the catheter. 
     FIG. 1   c  shows a view in cross-section through a catheter shaft  131  with a fluid-tight shaft wall  132  which encloses a lumen  135 . The lumen  135  can have, for example, a heat-insulating foam. The lumen  135  contains a first lumen  134  enclosed by a first shaft wall  138 . The lumen  135  further contains a second lumen  133  which is enclosed by a second shaft wall  137  and has a wire  136 . For example, a fluid can flow through the second lumen  133  and the first lumen  134 . In that case, for example, the fluid flows in the first and second lumens in respectively opposite directions. For that purpose, the first shaft wall  138  and the second shaft wall  137  are of fluid-tight nature. 
     FIG. 1   d  shows a view in cross-section through a catheter shaft  141  having a shaft wall  142  which encloses a first lumen  146 . Arranged in the first lumen  146  is a second lumen  143  which is enclosed by a second shaft wall  147 . A wire  144  is mounted by means of a heat-conductive adhesive  145  on the surface of the second shaft wall, which faces towards the first lumen. The second lumen  143  can guide a fluid. In this embodiment, the fluid in the second lumen can receive heat which is given off by the wire  144  and which is passed by way of the heat-conductive adhesive  145  and the second shaft wall  147  to the fluid. For that reason, the second shaft wall  147  is of a fluid-tight and heat-conducting nature. The heat-transmission resistance formed in this arrangement in respect of the lumen  146  from the wire  144  to the shaft wall  142  is higher than the heat-transmission resistance from the wire  144  to the lumen  143 , formed by the heat-conductive adhesive  145  and the heat-conductive second shaft wall  147 . 
     FIG. 1   e  shows a view in cross-section through a catheter shaft  151  with a fluid-tight shaft wall  152  which encloses a lumen  153 . The lumen  153  can have for example a heat-insulating foam. The lumen  153  contains a first lumen  158  which is enclosed by a first shaft wall  157 . The lumen  153  further contains a second lumen  154  which is enclosed by a second shaft wall  155  and has a wire  156 . The lumen  153  further contains a third lumen  159  which is enclosed by a shaft wall  160 . The three lumens  154 ,  158  and  159  can have a fluid flowing therethrough. In that case, the fluid flows, for example, in the first lumen  158  and in the second lumen  154  in the same direction, for example, to the distal end of the catheter, and in the third lumen  159  in the opposite direction thereto, for example to the proximal end of the catheter. For that purpose, the shaft walls  155 ,  157  and  160  are of a fluid-tight nature. 
     FIG. 2   a  is a diagrammatic view in longitudinal section of the distal end of an ablation catheter  201  with a shaft wall  203  which extends from the distal end of the catheter to the proximal end thereof and which encloses a first lumen  209  and a second lumen  207 . The lumens  209  and  207  are separated from each other by a separating wall  211  arranged along the catheter longitudinal axis, wherein the separating wall  211  at the distal end of the catheter has a fluid passage in the form of an aperture  208 . Mounted to the outer distal end of the catheter is an electrode  205  which, by way of a heat-conductive, electrically insulating layer  206 , is in thermal contact with the lumen  207  and with the lumen  209 . The shaft wall  203 , the separating wall  211  and the insulating layer  206  are of fluid-tight nature. The electrode  205  has an electrode temperature sensor  222  which is connected to an electrical connecting line  220  which extends along the catheter longitudinal axis to the proximal end of the catheter and which is arranged in the second lumen  207 . The catheter also includes a fluid temperature sensor  226  which is arranged in the region of the distal end of the catheter  201  in the first lumen  209  and which is connected to an electrical connecting line  227  extending along the catheter longitudinal axis to the proximal end of the catheter in the first lumen. In the region of the distal end, the catheter also includes a wire temperature sensor  228  which is connected to a connecting line  229  extending in the second lumen to the proximal end of the catheter and which is arranged in the second lumen  207 . 
   When a fluid flows in the second lumen  207  to the distal end of the catheter and flows back by way of the aperture  208  and the first lumen to the proximal end of the catheter, the increase in temperature of the fluid caused by the wires is detected by the temperature sensor  228 , the temperature of the electrode  205  is detected by the electrode temperature sensor  222  and the temperature of the fluid after receiving the heat of the electrode head, which is given off by way of the insulating layer  206 , is detected by the temperature sensor  226 . The catheter also has a feed line wire  224  which is passed in the second lumen  204  from the distal end of the catheter to the proximal end thereof along the catheter longitudinal axis and is fixed at the distal end of the catheter. The feed line wire  224  is of an electrically conducting nature and is electrically connected to the electrode  205 . In this embodiment, high-frequency energy can be fed to the electrode  205  by way of the electrically conducting feed line wire  224 . 
     FIG. 2   b  diagrammatically shows a view in longitudinal section of the distal end of an ablation catheter  230  with a shaft wall  203  which extends from the distal end of the catheter to the proximal end and which encloses a lumen  237 . Mounted to the outer distal end of the catheter is an electrode  235 , which is electrically connected to the proximal end of the ablation catheter  230  by way of a feed line wire  238 . The feed line wire  238  extends in the lumen  237 . The shaft wall  203  is of a fluid-tight nature. The electrode  205  has an electrode temperature sensor  252  which is connected to an electrical connecting line  250  extending along the catheter longitudinal axis to the proximal end of the catheter and which is arranged in the lumen  237 . The catheter also includes a wire temperature sensor  255 , which is arranged in the lumen  237  in the region of the distal end of the catheter  230  and which is connected to an electrical connecting line  257  extending to the proximal end of the catheter in the first lumen along the catheter longitudinal axis. The electrode  235  has openings  234  which are in fluid communication with the lumen  237  so that fluid can flow outwardly through the openings. 
     FIG. 3  shows an arrangement  301  with a supply device  330  and an ablation catheter which is connected to the supply device  330  by way of a socket  332 . 
   The ablation catheter includes a catheter shaft  306  which opens into a handle  336 , the handle  336  being connected to a flexible hose  333 . Mounted to the flexible hose  333  at the end is a plug  331  which can be connected to the socket  332 . 
   The distal end of the catheter shaft  306  is shown in an enlargement window  302  in  FIG. 3 . The catheter shaft  306  has a shaft wall  303  which encloses a first lumen  309  and a second lumen  307 . The first lumen  309  and the second lumen  307  are separated from each other by a separating wall  311 . The arrangement of the shaft wall  303 , the first lumen  309 , the second lumen  307  and the separating wall  311  is similar to the structure shown in cross-section in  FIG. 1   b . The first lumen  309 , the second lumen  307  and the separating wall  311  are provided from the distal end of the catheter shaft  306  to the proximal end of the catheter shaft  306 . The catheter shaft has a control wire  328  which is fixed at the distal end of the catheter shaft and which is guided along the catheter longitudinal axis in the first lumen  309  into the handle  336 , the control wire  328  being connected to the slider  337  in the handle  336 . Actuation of the slider  337  causes curvature of the distal end of the catheter with a directional component in orthogonal relationship with the catheter longitudinal axis. An ablation electrode  305  is mounted at the outer distal end of the catheter shaft. The ablation electrode is in the form of a bipolar electrode, and for that purpose, includes a counterpart electrode  304  which is in the form of a ring electrode at the distal end of the catheter shaft. The catheter shaft has an electrode temperature sensor  322 , which is mounted to the high-frequency electrode  305  and connected to a temperature sensor line  320 , which opens through the second lumen  307  into the handle  336 , along the catheter longitudinal axis. A wire temperature sensor  325  is arranged in the region of the distal end in the second lumen  307  and is connected to the temperature sensor line  320 , which is in the form of a two-channel temperature sensor line. A fluid temperature sensor is arranged in the region of the distal end of the catheter in the first lumen and is connected to an electrical fluid temperature sensor line  327 , which is guided along the catheter longitudinal axis in the first lumen and which opens into the handle  336 . The high-frequency electrode  305  and the counterpart electrode  304  are connected to a two-channel high-frequency line  324 , which is guided in the second lumen along the longitudinal axis of the electrode line and opens into the handle  336 . The first lumen  309 , the fluid temperature sensor line  327  and the temperature sensor line  320  are brought together in the handle  336  to constitute a line bundle  335 , which communicates with the plug  331 . A first fluid line  353 , a second fluid line  352 , an electrical high-frequency line  368  and a three-channel temperature sensor line  366  open into the socket  332  of the supply device  330 . When the plug  331  is coupled to the socket  332  the first fluid line  353  is in fluid communication with the first lumen  309 , the second fluid line  352  is in fluid communication with the second lumen  307 , the electrical high-frequency line  368  is electrically connected to the high-frequency line  324  and the three-channel temperature sensor line  366  is electrically connected to the fluid temperature sensor line  327  and the temperature sensor line  320 . 
   The supply device  330  includes a fluid feed unit  344  having a. circulation pump  374  connected to fluid lines  355  and  354 . The supply device  330  also has a controllable cooling unit  342  with a control input having a thermostat for maintaining a predetermined fluid temperature. The cooling unit  342  is connected to the fluid lines  354 ,  355 ,  352  and  353 , wherein the fluid line  355  is in fluid communication by way of the cooling unit  342  with the second fluid line  352  and the fluid line  354  is in fluid communication by way of the cooling unit  342  with the first fluid line  353 . The cooling unit  342  is preferably in the form of a Peltier cooling unit and for that purpose includes at least one Peltier element. The arrangement  301  also includes a fluid feed container  358  which is connected by way of a fluid feed line  356  to the fluid feed unit  344  and there is connected by way of an inlet valve  378  contained in the fluid feed unit to the pump intake  377  to which the fluid line  354  is also connected. The arrangement  301  also includes a fluid discharge container  359  into which opens a fluid discharge line  357 , which, by way of an excess pressure valve  376  contained in the fluid feed unit  344 , is in fluid communication with the circulation pump outlet  375  upon opening of the excess pressure valve  376 . The circulation pump outlet  375  is connected to the fluid line  355 . The valves  376  and  378  as well as the pump  374  are adapted to be controllable. For that purpose, the fluid feed unit  344  has a control input and is connected by way of a control line  360  to the control output of a temperature monitoring and control unit  346 . The fluid feed unit  344  is adapted, on the basis of the control information of a control signal received by way of the control line  360 , selectively to set the pump volume of the circulation pump  374  or to open or close the valves  378  and  376 . The temperature monitoring and control unit  346  is connected at the output side by way of an electrical connecting line  362  for controlling the cooling unit  342  to the control input thereof. The cooling unit  342  is adapted to cool a fluid flowing through the cooling unit  342 , on the basis of a control signal received by way of the control line. The cooling unit  342  can also be adapted to set a fluid temperature or cooling efficiency corresponding to the control signal. For that purpose, the cooling unit  342  can include a temperature regulator. The temperature monitoring and control unit is operatively connected by way of a three-channel temperature sensor line  366  to the temperature sensors  325 ,  326  and  322  contained in the catheter shaft. 
   The fluid temperature sensor  326  can also be arranged in the handle  336  alternatively to the arrangement in the first lumen  309  of the catheter shaft  306  and there is also arranged in the first lumen  309  or is connected in heat-conductive relationship to the first lumen  309 . 
   The supply device  330  also includes a high-frequency generator  340  which is connected by way of an electrical high-frequency line  368  and by way of an electrical high-frequency line  324  to the high-frequency electrode  305  and the counterpart electrode  304 . The electrical high-frequency lines  368  and  324  are of a two-channel configuration for that purpose. The high-frequency generator  340  is connected by way of a high-frequency control line  364  to the temperature monitoring and control unit  346 . The temperature monitoring and control unit  346  is connected to an input unit  380  by way of a bidirectional data bus  381 , the input unit being connected to a display  382  by way of a connecting line  383 . 
   The mode of operation of the arrangement will now be described in greater detail: 
   Operating parameters for operation of the ablation catheter can be input into the temperature monitoring and control unit  346  by way of the input unit  380  which includes, for example, a keypad. The parameters are, for example, switching a high-frequency power on or off or preselecting a predetermined high-frequency power which is to be delivered by way of the high-frequency electrode  305  or preselecting a desired ablation electrode temperature. The temperature monitoring and control unit  346 , which, for example, comprises a microprocessor, is adapted, in accordance with the setting by the input unit  380 , to send a signal corresponding to the input value to the high-frequency generator  340  by way of the high-frequency control line  364  for producing a high-frequency power corresponding to the input value. The high-frequency generator  340  is adapted, on the basis of the control signal received by way of the high-frequency control line  364 , to deliver a high-frequency power corresponding to the input value by way of the electrical high-frequency line  368  and the high-frequency electrode  305  operatively connected thereto. The temperature sensors  325 ,  326  and  322  are adapted to produce a temperature signal representative of the detected temperature. The temperature signals respectively produced by the temperature sensors are available to the temperature monitoring and control unit  346  by way of the temperature sensor lines  327  and  320  respectively connected to the temperature sensors and by way of the three-channel temperature sensor line  366 . 
   The temperature monitoring and control unit  346  is adapted to evaluate the temperature signals received by way of the three-channel temperature sensor line  366  and to control the pump volume of the circulation pump  374  by way of the connecting line  360 , the cooling output of the cooling unit  342  by way of the connecting line  362  and the high-frequency power by way of the high-frequency control line  364 , in accordance with a regulating algorithm which is predetermined in the temperature monitoring and control unit  346 , and to produce control signals corresponding thereto. The temperature monitoring and control unit  346  can send signals corresponding to items of status information by way of the bidirectional data bus  381 , the input unit  380  and the connecting line  383  to the display  382  which can display those items of status information. The items of status information can be for example the temperature of the high-frequency electrode  305 , the temperature, detected by the fluid temperature sensor  326 , of the fluid  370  which is in the first lumen  309 , and the temperature, detected by the wire temperature sensor  325 , of the fluid  370 , which is in the second lumen  307 . The temperature monitoring and control unit  346  is also adapted to evaluate a signal received by way of the connecting line  366  from a fluid sensor, which is mounted in the fluid feed unit and to monitor the fluid filling level and/or the fluid pressure in the fluid circuit formed by the fluid lines and the lumens and to suitably control the inlet valve  378  for the intake of a fluid  370  into the fluid circuit by way of the fluid feed line  365 . In the event of an excess pressure in the fluid circuit, produced by the rise in temperature of the catheter shaft, the excess pressure valve  376  is adapted to open at a predetermined excess pressure and thus to discharge excess fluid  372  into the fluid discharge container  359  by way of the fluid discharge line  357 . 
   The features set forth in the specific description can also be embodied considered in themselves independently of the other features set forth in this connection on a catheter or an arrangement with a catheter.

Technology Category: 1