Tissue heating and ablation systems and methods using predicted temperature for monitoring and control

• US 5,906,614 A
• Filed: 02/18/1997
• Issued: 05/25/1999
• Est. Priority Date: 11/08/1991
• Status: Expired due to Term

• Current Assignee: EP Technologies Incorporated (Boston Scientific Corporation)
• Original Assignee: EP Technologies Incorporated (Boston Scientific Corporation)
• Inventors: Panescu, Dorin, Stern, Roger A.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/801,484
• Time in Patent Office: 826 Days
• Field of Search: 606/27-34, 606/37-42, 606/45-52, 607/100-102, 600/549
• US Class Current: 606/42
• 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 18/20 using laser
• CPC Class Codes: A61B 2017/00092 using thermocouples
• CPC Class Codes: A61B 2017/00154 pulsed
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00095 high, i.e. heat conducting
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61B 2018/0066 without feedback, i.e. open loop control
• CPC Class Codes: A61B 2018/0069 using fuzzy logic
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00803 with temperature prediction
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple
• CPC Class Codes: A61B 2018/00886 Duration
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/128 generating two or more frequencies
• CPC Class Codes: A61B 2018/1467 using more than two electrodes on a single probe
• CPC Class Codes: A61B 2562/08 : Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61M 2205/6018 : providing set-up signals for the apparatus configuration

Abstract

Systems and methods employ an energy emitting electrode to heat tissue. The systems and methods derive a temperature prediction for a future time period. The systems and methods control the application of energy to the energy emitting electrode based, at least in part, upon the temperature prediction.

Claims

1. An apparatus for heating body tissue comprising

an electrode adapted to emit energy to heat body tissue,

a sensing element adapted to measure temperature at the electrode, and

a processing element, operabily connected to the sensing element, and adapted to take one or more samples of the temperature measured by the sensing element and to derive a temperature prediction for a future time from the one or more sampled temperatures.

2. A tissue heating apparatus according to claim 1

wherein the processing element is adapted to sample changes in temperature measured by the sensing element over time to derive the temperature prediction.

3. An apparatus according to claim 1

wherein the processing element is adapted to generate an output based upon the temperature prediction.

4. An apparatus according to claim 3

wherein the processing element is adapted to generate the output based upon comparing the temperature prediction to a prescribed temperature.

5. An apparatus according to claim 4

wherein the prescribed temperature is essentially constant over time.

6. An apparatus according to claim 4

wherein the prescribed temperature changes at least once as a function of time.

7. An apparatus according to claim 4

wherein the processing element includes a prescribed temperature input device.

8. An apparatus according to claim 1

wherein the processing element includes a temperature prediction parameter input device.

9. An apparatus according to claim 8

wherein the temperature prediction parameter input device includes means for changing at least one of the parameters as the processing element derives the temperature prediction.

10. A tissue heating apparatus according to claim 1

wherein the processing element is adapted to derive a temperature prediction for a region below the surface of the tissue.

22. An apparatus according to claim 1

wherein the processing element is adapted to derive a temperature prediction for a region below the surface of the tissue.

11. An apparatus for supplying energy to an electrode for heating tissue comprising

a generator adapted to be electrically coupled to an electrode and to supply energy to the electrode for heating tissue, and

a control system, operably connected to the generator, and adapted to supply power to the generator, the control system including

a sensing element adapted to measure temperature at the electrode, and

a processing element, operably connected to the sensing element, and adapted to take one or more samples of the temperature measured by the sensing element over time, derive a temperature prediction for a future time from the one or more sampled temperatures, and generate a power supply signal to control power supplied to the generator based upon the temperature prediction.

12. An apparatus according to claim 11

wherein the processing element is adapted to compare the temperature prediction to a prescribed temperature and generate the signal based upon the comparison.

13. An apparatus according to claim 12

wherein the prescribed temperature is essentially constant over time.

14. An apparatus according to claim 12

wherein the prescribed temperature changes at least once as a function of time.

15. An apparatus according to claim 11

wherein the processing element includes a prescribed temperature input device.

16. An apparatus according to claim 11

wherein the processing element includes a temperature prediction parameter input device.

17. An apparatus according to claim 16

wherein the temperature prediction parameter input device includes means for changing at least one of the parameters as the processing element samples temperatures to derive the temperature prediction.

18. An apparatus according to claim 11

wherein the processing element is adapted to average the temperature prediction.

19. An apparatus according to claim 11

wherein the processing element includes a low pass filter element with a selected time constant adapted to average the temperature prediction.

20. An apparatus according to claim 19

wherein the processing element includes a low pass filter time constant input device.

21. An apparatus according to claim 11

wherein the generator supplies radio frequency energy.

23. An apparatus for ablating tissue comprising

a generator adapted to be electrically coupled to an electrode to supply energy to the electrode for ablating tissue, and

a control system, operably connected to the generator, and adapted to supply power to the generator, the control system including

a sensing element adapted to measure temperature at the electrode, and

a processing element, operably connected to the sensing element, including

first means for taking one or more samples of the temperature measured by the sensing element over time

second means for deriving a temperature prediction for a future time from the one or more sampled temperatures,

third means for comparing the temperature prediction to a prescribed temperature,

fourth means for generating a power demand signal based upon the temperature comparison,

fifth means for comparing the power demand signal to a signal representing the power supplied to the generator, and

sixth means for adjusting the power supplied to the generator based upon the power comparison.

24. An apparatus according to claim 23

wherein the first means includes a temperature prediction parameter input device.

25. An apparatus according to claim 24

wherein the temperature prediction parameter input device includes means for changing at least one of the parameters as the first means derives the temperature prediction.

26. An apparatus according to claim 24

wherein the third means generates the power demand signal based, at least in part, upon a difference between the temperature prediction and the prescribed temperature.

27. An apparatus according to claim 26

wherein the third means generates the power demand signal based, at least in part, upon a change in the difference over time.

28. An apparatus according to claim 27

wherein the third means generates the power demand signal based, at least in part, upon a rate at which the difference changes over time.

29. An apparatus according to claim 23

wherein the prescribed temperature remains essentially constant over time.

30. An apparatus according to claim 23

wherein the prescribed temperature changes at least once as a function of time.

31. An apparatus according to claim 23

wherein the processing element further includes a prescribed temperature input device.

32. An apparatus according to claim 23

wherein the second means comprises means for deriving a temperature prediction for a region below the surface of the tissue.

33. A method for ablating body tissue comprising the steps of

supplying ablating energy to an electrode,

sensing temperature at the electrode,

taking one or more samples of temperature sensed at the electrode,

deriving a temperature prediction for a future time period from the one or more temperature samples, and

generating a signal to control the supply of ablating energy based at least in part upon the temperature prediction.

34. A method according to claim 33

wherein the step of generating the signal comprises comparing the temperature prediction to a prescribed temperature and generating the signal based upon the comparison.

35. A method according to claim 33

wherein the step of deriving a temperature prediction for a future time period comprises deriving a temperature prediction for a region below the surface of the tissue.