Process and apparatus for the detection of catheter-tissue contact, and also of interactions with the tissue catheter ablation

• US 6,304,776 B1
• Filed: 12/23/1999
• Issued: 10/16/2001
• Est. Priority Date: 04/01/1997
• Status: Expired due to Term

• Current Assignee: Axel Muntermann
• Original Assignee: Axel Muntermann
• Inventors: Muntermann, Axel
• Primary Examiner(s): Lacyk, John P.
• Assistant Examiner(s): WINGOOD, PAMELA LYNN
• Application Number:
  US09/402,222
• Time in Patent Office: 663 Days
• Field of Search: 600/547, 600/443, 600/523
• US Class Current: 600/547
• CPC Class Codes: A61B 18/12 by passing a current through the tissue to be heated, e.g. high-frequency current
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2018/0066 without feedback, i.e. open loop control

Abstract

In a process and an apparatus for the detection of the contact and/or the interaction of a catheter arranged in a patient'"'"'s vessel, in particular in a patient'"'"'s blood stream, with the patient'"'"'s tissue, in order to contribute to an improved detection of this contact or to make it possible for the first time to permit statements during an ablation process regarding the ablation depth or regarding the interaction with the tissue, a device is provided for the detection of a voltage at at least one catheter electrode, wherein the voltage between the catheter electrode and a further electrode is measured, and wherein the further electrode is a neutral electrode in contact with the patient'"'"'s body or a further electrode installed on the catheter.

Claims

1. Process for the determination of at least one of the interaction and the contact of a catheter arranged in a patient'"'"'s vessel, particularly in a patient'"'"'s blood stream, with the patient'"'"'s tissue, characterized by the detection of the voltage signals which arise when an electrode of the catheter at least one of comes into contact, and stays in contact, with the patient'"'"'s tissue.

2. Process according to claim 1, wherein the detection of the voltage signals includes their measurement with a high-ohmic measuring device, which preferably has an input resistance of at least 500 KΩ

.

3. Process for HF catheter ablation, in which tissue sections of a patient to be treated are ablated by the irradiation of high frequency power, furthermore including a process according to claim 1 for the detection of at least one of the contact between the catheter and the patient'"'"'s tissue and of the temperature of the patient'"'"'s tissue.

4. Process according to claim 3, characterized in that the catheter used for ablation has available several, separately controllable, ablation electrodes, at which the voltage signals appear, or includes further separately connected electrodes which are respectively allocated to ablation electrodes, wherein the voltage signals are detected at the separate ablation electrodes or at the allocated electrodes.

5. Process according to claim 3, characterized in that the voltage signals are detected during the performance of the HF ablation, wherein the high frequency signals for ablation are applied either continuously or in a pulsed manner.

6. Process according to claim 3, characterized in that the voltage signals are detected during the delivery of the HF power, and when a threshold value is fallen below or exceeded, effect the switching off or at least the reduction of the delivery of the high frequency power.

7. Process according to claim 3, characterized in that the high frequency power delivered by the catheter is integrated over time, as long as the voltage signal is situated above a predetermined threshold, and the integrated power is calculated and displayed as ablation energy hitherto delivered into the tissue.

8. Process according to claim 7, characterized in that on reaching a predetermined ablation energy value, the delivery of high frequency power to the allocated catheter electrode is shut off or at least reduced.

9. Process according to claim 3, characterized in that the course of the voltage signals and also of the delivered and/or of the time integrated ablation power is displayed and stored, allocated to the respective catheter electrode.

10. Process according to claim 3, characterized in that the voltage signal which appears is displayed optically and/or acoustically, wherein the optical display takes place in the form of bar charts, real time representation of the voltage signals in a two-dimensional coordinate system and/or in a display of time-integrated power data.

11. Apparatus, in particular for the carrying out of processes according to claim 1, characterized by a device (1) for detection of a voltage on at least one catheter electrode (a, b), wherein the voltage between the catheter electrode (a, b) and a further electrode (a, b, 4) is measured, wherein the further electrode is a neutral electrode (4) which remains in contact with the body of the patient to be treated, or a further electrode (a, b) installed on the catheter (3).

12. Apparatus according to claim 11, characterized in that the voltage measurement takes place substantially with such a high-ohmic input that no currents appear which disturb the ablation or the measurement of the EKG signals.

13. Apparatus according to claim 11, characterized in that the catheter electrodes (a, b) attached to the voltage measuring device (1), and the neutral electrode (4), all consist of platinum or are coated with platinum.

14. Apparatus according to claim 11, characterized in that the voltage measuring device (1) has an input resistance of at least more than 100 KΩ

and preferably several MΩ

.

15. Apparatus according to claim 14, characterized in that the voltage measuring device (1) has an input resistance of about 1 megohm and an input capacitance of no more than 30 pF.

16. Apparatus according to claim 11, characterized in that the measurement of the voltage can be carried out by means of the voltage measuring device (1) during the delivery of the high frequency ablation power.

17. Apparatus according to claim 11, characterized in that the ablation catheter (3) includes high frequency ablation electrodes (a, b) consisting of platinum or coated with platinum, at which the voltage signals for recognizing the catheter-tissue contact and/or the tissue temperature are taken off.

18. Apparatus according to claim 11, further characterized by a low pass filter (2) for the suppression of interferences of the high frequency ablation signals and also of ripple interference.

19. Apparatus according to claim 11, further characterized by a device (15) for the display and storage of the voltage signals, and also preferably also of the delivered high frequency ablation power and energy.

20. Apparatus according to claim 19, characterized in that the course of the voltage signals and also the instantaneously delivered and/or the time-integrated ablation power are displayed and stored, allocated to the respective catheter electrodes (a, b).

21. Apparatus according to claim 19, further characterized by a device (16, 19) for the display and/or evaluation of the voltage signals, by means of which the voltage signals which arise are displayed optically or acoustically, wherein the optical display preferably takes place in the form of bar charts, real time representation of the voltage signal in a two-dimensional coordinate system, and/or by the display of power data which are integrated over time.

22. Apparatus according to claim 11, further characterized by a device (15, 16, 19) by means of which the voltage signals are detected during the delivery of the high frequency power and, in the case that the voltage signal falls below a preassignable, settable threshold value (Ug, 17), the switching off, or at least the reduction, of the delivery of the high frequency power is effected.

23. Apparatus according to claim 11, further characterized by a device (18, 19) by which the high frequency power delivered by the catheter is integrated over time, as long as the voltage signals are situated above a predetermined threshold value (Ug, 18) and by which the integrated power is calculated and displayed as ablation energy delivered into the tissue hitherto, or attained interaction with the tissue, or attained ablation depth in the tissue.

24. Apparatus according to claim 23, further characterized in that on reaching a predetermined value of ablation energy delivered into the tissue hitherto, or attained interaction with the tissue or attained depth of ablation, the delivery of high frequency power to the associated catheter electrode is switched off or at least reduced.