RF ablation apparatus and method using unipolar and bipolar techniques

• US 20010008967A1
• Filed: 01/10/2001
• Published: 07/19/2001
• Est. Priority Date: 05/05/1998
• Status: Active Grant

• Current Assignee: Sherman, Marshall L.
• Original Assignee: Sherman, Marshall L.
• Inventors: Sherman, Marshall L.
• Granted Patent: US 6,488,678 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• 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 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00351 Heart
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00654 with individual control of each of a plurality of energy emitting elements
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00714 Temperature
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00738 Depth, e.g. depth of ablation
• CPC Class Codes: A61B 2018/0075 Phase
• CPC Class Codes: A61B 2018/00755 Resistance or impedance
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/126 bipolar
• CPC Class Codes: A61B 2018/1273 including multiple generators in one device
• CPC Class Codes: A61B 2018/1467 using more than two electrodes on a single probe

Abstract

An apparatus for delivering energy to a biological site includes an electrode device having a plurality of electrodes, the electrode device positioned proximal the biological site. A power control system supplies power having a controllable phase angle to each of the electrodes. A backplate is also positioned proximal the biological site so that the biological site is interposed between the electrode device and the backplate. The backplate is maintained at the reference voltage level in relation to the power. The power control system controls the phase angle of the power so that the current flow between the electrodes and between the electrodes and the backplate results in the continuity and depth of lesions desired. In a preferred embodiment, the electrodes are arranged in a substantially linear array.

Claims

1. An apparatus for delivering energy to a biological site, said apparatus comprising:

a catheter having a plurality of electrodes at its distal end, the distal end positionable so that the electrodes are located at the biological site;

a backplate positionable proximal the biological site so that the biological site is interposed between the electrodes and the backplate;

a power control system providing power to each of the electrodes, the power having a duty cycle with an on period and an off period;

wherein during the on period of the duty cycle, the power is selected such that at least two electrodes have voltage levels that differ from each other and at least one electrode has a voltage level that differs from the backplate so that current flows between the two electrodes and between at least one electrode and the backplate; and

wherein during the off period of the duty cycle, the power is selected such that each electrode and the backplate have substantially the same voltage levels so that substantially no current flows between the electrodes and between the electrodes and the backplate.

2. The apparatus of

claim 1

wherein the power control system provides separate power to each of the plurality of electrodes with the power being individually controllable as to duty cycle.

3. The apparatus of

claim 1

wherein the power control system controls the duty cycle of the power to be approximately ten percent.

4. The apparatus of

claim 1

further comprising:

a temperature sensing device located at least one of the electrodes for providing a temperature signal to the power control system representative of the temperature at the electrode;

wherein the power control system controls the duty cycle of the power in response to the temperature signal.

5. The apparatus of

claim 1

further comprising:

a measurement device that senses at least one characteristic of the power applied to at least one electrode and provides a power measurement signal;

wherein the power control system receives the power measurement signal and determines an impedance measurement based on the power and controls the duty cycle of a power in response to the power measurement signal.

6. The apparatus of

claim 5

further comprising:

a temperature sensing device located at least one of the electrodes for providing a temperature signal to the power control system representative of the temperature at the electrode;

wherein the power control system controls the duty cycle of the power in response to the temperature signal and in response to the power measurement signal.

7. The apparatus of

claim 1

wherein the power control system provides power with different phase angles to at least two of the electrodes.

8. The apparatus of

claim 7

wherein the power differs in phase by an amount greater than zero degrees but less than 180 degrees.

9. The apparatus of

claim 7

wherein the power differ in phase by an amount approximately equal to 132 degrees.

10. The apparatus of

claim 7

wherein power provided to adjacent electrodes has different phase angles.

11. The apparatus of

claim 7

comprising at least three electrodes arranged in a linear array with the power provided to the center electrode having a different phase angle than at least one adjacent electrode.

12. The apparatus of

claim 7

wherein the power control system provides separate power to each of the plurality of electrodes with the power being individually controllable as to phase angle.

13. The apparatus of

claim 1

wherein the plurality of electrodes are formed into a first electrode group and a second electrode group with at least one electrode in each group, wherein all electrodes in the first group receive a first power signal from the power control system and all electrodes in the second group receive a second power signal from the power control system with the first power signal establishing a first potential at each of the electrodes in the first electrode group and the second power signal establishing a second potential at each of the electrodes in the second electrode group, with each of the first and second potentials being different from each other and from the potential at the backplate.

14. The apparatus of

claim 13

wherein the first power signal has a different phase angle from the second power signal.

15. The apparatus of

claim 14

wherein the electrodes of the first group of electrodes are interspaced between the electrodes of the second group of electrodes such that each electrode from the first group is adjacent at least one electrode from the second group.

16. The apparatus of

claim 15

wherein the electrodes are arranged into a linear array at the distal end of the catheter.

17. The apparatus of

claim 1

further comprising:

a power interruption device connected to the power control system;

wherein the power control system is adapted to control the power interruption device to interrupt power to a selected electrode.

18. The apparatus of

claim 17

wherein the power interruption device comprises a relay.

19. An apparatus for delivering energy to heart tissue, said apparatus comprising:

a catheter having at least three electrodes arranged in a linear array at its distal end, the distal end positionable so that the electrodes are located at the heart tissue;

a backplate positionable so that the heart tissue is interposed between the electrodes and the backplate;

a power control system providing power to each of the electrodes, the power having a duty cycle with an on period and an off period;

wherein during the on period of the duty cycle, at least two of the electrodes have different phase angles and the power at one of the electrodes has a voltage level that differs from the backplate so that current flows between said two electrodes and at least one electrode and the backplate; and

wherein during the off period of the duty cycle, the power is selected such that each electrode and the backplate have substantially the same voltage levels so that substantially no current flows between the electrodes and between the electrodes and the backplate.

20. The apparatus of

claim 19

wherein the power signals differ in phase by an amount greater than zero degrees but less than 180 degrees.

21. The apparatus of

claim 19

wherein the power signals differ in phase by an amount approximately equal to 132 degrees.

22. The apparatus of

claim 19

wherein power provided to adjacent electrodes has different phase angles.

23. The apparatus of

claim 19

wherein the power control system provides separate power to each of the plurality of electrodes with the power to each electrode being individually controllable as to phase angle.

24. The apparatus of

claim 19

wherein the power control system provides separate power to each of the plurality of electrodes with the power to each electrode being individually controllable as to duty cycle.

25. The apparatus of

claim 19

wherein the power control system controls the duty cycle of the power to be approximately ten percent.

26. The apparatus of

claim 19

further comprising:

a temperature sensing device located at least one of the electrodes for providing a temperature signal to the power control system representative of the temperature at the electrode;

wherein the power control system controls the duty cycle of the power in response to the temperature signal.

27. The apparatus of

claim 19

further comprising:

a measurement device that senses at least one characteristic of the power applied to at least one electrode and provides a power measurement signal;

wherein the power control system receives the power measurement signal and determines an impedance measurement based on the power and controls the duty cycle of the power in response to the power measurement signal.

28. The apparatus of

claim 27

further comprising:

a temperature sensing device located at least one of the electrodes for providing a temperature signal to the power control system representative of the temperature at the electrode;

wherein the power control system controls the duty cycle of the power in response to the temperature signal and in response to the power measurement signal.

29. The apparatus of

claim 19

further comprising:

a power interruption device connected to the power control system;

wherein the power control system is adapted to control the power interruption device to interrupt power to a selected electrode.

30. A method for delivering energy to a biological site, said method comprising the steps of:

positioning a catheter having a plurality of electrodes at its distal end at the biological site;

positioning a backplate proximal the biological site so that the biological site is interposed between the electrode device and the backplate;

providing power to each of the electrodes, the power having a duty cycle with an on period and an off period;

during the on period of the duty cycle, selecting the power such that at least two electrodes have voltage levels that differ from each other and at least one electrode has a voltage level that differs from the backplate so that current flows between the two electrodes and between at least one electrode and the backplate; and

during the off period of the duty cycle, selecting the power such that each electrode and the backplate have substantially the same voltage levels so that substantially no current flows between the electrodes and between the electrodes and the backplate.

31. The method of

claim 30

wherein the step of positioning a catheter comprises the step of positioning a catheter having a plurality of electrodes arranged into a linear array at the distal end of the catheter at the biological site such that a select number of the plurality of electrodes are in contact with the biological site.

32. The apparatus of

claim 30

wherein the step of selecting the power during the on period of the duty cycle comprises the further step of providing the power with different phase angles to at least two of the electrodes.

33. The method of

claim 32

wherein the step of providing the power comprises the further step of providing power that differs in phase by an amount greater than zero degrees but less than 180 degrees to the electrodes.

34. The method of

claim 32

wherein the step of providing the power that differs in phase angle between the electrodes comprises the step of providing power that differs in phase by approximately 132 degrees.

35. The method of

claim 32

wherein the step of selecting the power during the on period of the duty cycle comprises the step of providing power having different phase angles to adjacent electrodes.

36. The method of

claim 30

further comprising the step of providing separate power to each of the plurality of electrodes and individually controlling each electrode'"'"'s power as to phase angle.

37. The method of

claim 30

further comprising the step of controlling the duty cycle of the power.

38. The method of

claim 37

further comprising the steps of:

sensing the temperature at the electrodes and providing a temperature signal to the power control system representative of the temperature at the electrodes; and

controlling the duty cycle of the power in response to the temperature signal.

39. The method of

claim 37

further comprising the steps of:

sensing at least one characteristic of the power applied to at least one electrode and providing a power measurement signal;

determining an impedance measurement based on the power, and

controlling the duty cycle of the power in response to the power measurement signal.

40. The method of

claim 39

further comprising:

sensing the temperature at the electrodes and providing a temperature signal to the power control system representative of the temperature at the electrodes;

controlling the duty cycle of the power in response to the temperature signal and the power measurement signal.

41. The method of

claim 36

further comprising the step of providing separate power to each of the plurality of electrodes and individually controlling the power to each electrode as to duty cycle.

42. The method of

claim 30

further comprising the steps of:

forming the plurality of electrodes into a first electrode group and a second electrode group with at least one electrode in each group;

applying power to all electrodes in the first group from the power control system; and

applying power to all electrodes in the second group from the power control system;

wherein the power applied to the first group establishes a first potential at each of the electrodes in the first electrode group and the power applied to the second group establishes a second potential at each of the electrodes in the second electrode group with each of the first and second potentials being different from each other and from the potential at the backplate.

43. The method of

claim 42

comprising the step of controlling the phase angle of the first power signal to be different from the phase angle from the second power signal.

44. The method of

claim 43

comprising the further step of interspacing the electrodes from the first group of electrodes with the electrodes of the second group of electrodes such that each electrode from the first group is adjacent at least one electrode from the second group.

45. The method of

claim 42

wherein the electrodes are arranged into a linear array at the distal end of the catheter.

46. The method of

claim 42

further comprising the step of:

interrupting the power from the power control system when the impedance of a selected electrode rises above a predetermined level.

47. A method for delivering energy to a biological site, said method comprising the steps of:

positioning a catheter having a plurality of electrodes at its distal end at the biological site;

positioning a backplate proximal the biological site so that the biological site is interposed between the electrode device and the backplate;

providing power to each of the electrodes, the power having a duty cycle with an on period and an off period;

during a first segment of the on period, establishing a voltage potential between at least one electrode and the backplate so that energy flows through the biological site between the electrode and the backplate; and

during a second segment of the on period, establishing a voltage potential between at least two of the electrodes so that energy flows through the biological site between the electrodes.

48. The method of

claim 47

wherein the duration of the first segment is approximately one-fourth of the on period and the duration of the second segment is approximately three-fourths of the on period.

49. The method of

claim 47

wherein, during the first segment, each electrode has substantially the same voltage level such that substantially no current flows between the electrodes.

50. The method of

claim 47

wherein, during the second segment, the voltage potential between at least two electrodes is established by providing power to each of the electrodes having voltage levels that differ from each other.

51. The apparatus of

claim 50

wherein the step of providing power comprises the further step of providing the power with different phase angles to at least two of the electrodes.

52. The method of

claim 51

wherein the step of providing power comprises the further step of providing power that differs in phase by an amount greater than zero degrees but less than 180 degrees to at least two of the electrodes.

53. The method of

claim 51

wherein the step of providing power that differs in phase angle comprises the step of providing power that differs in phase by approximately 132 degrees to at least two of the electrodes.

54. The method of

claim 50

wherein the step of providing power comprises the step of providing power having different phase angles to adjacent electrodes.

55. The method of

claim 50

further comprising the step of providing separate power to each of the plurality of electrodes and individually controlling the power to each electrode as to phase angle.

56. The method of

claim 50

further comprising the step of providing separate power to each of the plurality of electrodes and individually controlling the power to each electrode as to duty cycle.

57. The method of

claim 47

wherein, during the second segment, the voltage potential between at least two electrodes is established by connecting at least one electrode to a first potential and providing power to at least one of the electrodes having a voltage level different than the first potential.

58. The method of

claim 47

further comprising, during the second segment, the steps of:

forming the plurality of electrodes into a first electrode group and a second electrode group with at least one electrode in each group;

connecting all electrodes in the first group to a first potential; and

applying power to all electrodes in the second group from the power control system with the power establishing a second potential different from the first potential at each of the electrodes in the second electrode group.

59. The method of

claim 58

comprising the further step of interspacing the electrodes from the first group of electrodes with the electrodes of the second group of electrodes such that each electrode from the first group is adjacent at least one electrode from the second group.

60. The method of

claim 58

wherein the electrodes are arranged into a linear array at the distal end of the catheter.