Catheter

1. A catheter for intravascular application, with a proximal and a distal end and a catheter longitudinal axis, the catheter 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,

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,

wherein at least one portion of the length of the catheter which is adapted for introduction into a body and is further adapted to provide

a lower level of heat-transmission resistance obtains between a fluid in the lumen and the electrically 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,

wherein the catheter includes at least one 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.

2. A catheter as set forth in claim 1 , characterized in that the catheter has a first and a second lumen which are adapted to guide a fluid, which extend from the proximal end of the catheter into the proximity of the distal end of the catheter and which are enclosed by the shaft, and in the region of the distal end the catheter has a fluid passage between the first lumen and the second lumen so that fluid can flow in the first lumen in the direction of the distal end and from there into the fluid passage and in the second lumen back to the proximal end.

3. A catheter as set forth in claim 1 , characterized in that in the proximity of the distal end, the catheter has at least one opening which is in fluid communication with at least one of the lumen and which is so designed that fluid can flow outwardly from the catheter.

4. A catheter as set forth in claim 3 , characterized in that the catheter has at least one temperature sensor which is arranged along the longitudinal axis of the catheter in the region of the portion of the catheter shaft which is provided for intracorporeal invasion, spaced from ablation electrodes.

5. A catheter as set forth in claim 3 , characterized in that the catheter shaft has three lumens which are respectively adapted to guide a fluid and of which a lumen in the form of a wire-guiding lumen in which at least one wire to be cooled is arranged.

6. A catherter as set forth in claim 1 , characterized in that the catheter additionally has at least one second temperature sensor adapted for detecting the temperature of the fluid or of the shaft wall.

7. A catheter as set forth in claim 1 , characterized in that the wire is an electrical feed line.

8. A catheter as set forth in claim 1 , characterized in that the wire is a control wire which is arranged displaceably in an inner lumen in the direction of the catheter longitudinal axis.

9. A catheter as set forth in claim 1 , characterized in that the catheter comprises, along the catheter longitudinal axis, a plurality of temperature sensors which are so arranged as to detect the temperature of the wire, the shaft wall, a lumen, or a combination thereof

10. A catheter as set forth in claim 1 , characterized in that the catheter is an ablation catheter.

11. A catheter as set forth in claim 10 , comprising an ablation electrode and three lumens, characterized in that at least one wire to be cooled is arranged in a first lumen and the distal end is adapted to feed exclusively a fluid flowing in a second lumen to the ablation electrode for cooling purposes, and to return the fluid in a third lumen to the proximal end.

12. A catheter as set forth in claim 1 , characterized in that the catheter is a guide wire.

13. A catheter as set forth in claim 1 , characterized in that the catheter is a mapping catheter.

14. An arrangement for intravascular invasion including a catheter as set forth in claim 1 , and

a fluid feed unit which is in fluid communication with at least one lumen of the catheter and adapted to produce a fluid flow into the lumen.

15. An arrangement as set forth in claim 14 , characterized in that the fluid feed unit includes a controllable pump unit which is in fluid communication at least with one lumen of the catheter and which is adapted to pump a fluid into the lumen in dependence on a fluid control signal.

16. An arrangement as set forth in claim 15 , characterized in that the arrangement has a temperature monitoring unit which is operatively connected to at least one temperature sensor, the pump unit or a cooling unit or both, wherein 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.

17. An arrangement as set forth in claim 14 , characterized in that the arrangement includes a cooling unit which is in fluid communication with at least one lumen of the catheter and the cooling unit is adapted to take heat from a fluid in dependence on a cooling control signal.

18. An arrangement as set forth in claim 17 , characterized in that the arrangement has a temperature monitoring unit which is operatively connected to at least one temperature sensor, a pump unit or the cooling unit or both, wherein 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.