Tissue heating and ablation systems and methods which predict maximum tissue temperature

• US 20030055419A1
• Filed: 09/24/2001
• Published: 03/20/2003
• Est. Priority Date: 06/07/1995
• Status: Active Grant

• Current Assignee: EP Technology (Boston Scientific Corporation)
• Original Assignee: EP Technology (Boston Scientific Corporation)
• Inventors: Panescu, Dorin, Swanson, David K., Fleischman, Sidney D.
• Granted Patent: US 6,652,513 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• 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 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00095 high, i.e. heat conducting
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00803 with temperature prediction
• CPC Class Codes: A61N 1/403 for thermotherapy, e.g. hyperthermia

Abstract

Systems and methods heat or ablate body tissue by positioning an electrode to transmit heat or ablation energy to a tissue region. The systems and methods measure a first temperature using a temperature sensing element associated with the electrode. The systems and methods also measure a second temperature using a temperature sensing element associated with the electrode. The systems and methods process at least one of the first and second temperatures to derive a prediction of maximum temperature of the tissue region. The systems and methods generate an output that controls the transmission of the heating or ablation energy based, at least in part, upon the maximum tissue temperature prediction.

Claims

1. An apparatus for heating tissue comprising

an electrode to transmit heating energy to a tissue region,

a first sensing element associated with the electrode for measuring a first temperature,

a second sensing element associated with the electrode for measuring a second temperature, and

a processing element to process one or more temperatures measured by the first and second sensing elements and to derive therefrom a prediction of maximum temperature of the tissue region.

2. An apparatus according to claim 1

wherein the processing element generates an output based upon the maximum tissue temperature prediction.

3. An apparatus according to claim 2

wherein the processing element generates the output based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

4. An apparatus according to claim 3

wherein the prescribed temperature remains essentially constant over time.

5. An apparatus according to claim 3

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

6. An apparatus according to claim 3 or 4 or 5

wherein the processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to generate the output.

7. An apparatus according to claim 1

wherein the processing element controls the transmission of heating energy by the electrode based, at least in part, upon the maximum tissue temperature prediction.

8. An apparatus according to claim 7

wherein the processing element controls the transmission of heating energy based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

9. An apparatus according to claim 8

wherein the prescribed temperature remains essentially constant over time.

10. An apparatus according to claim 8

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

11. An apparatus according to claim 8 or 9 or 10

wherein the-processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to control the transmission of heating energy.

12. An apparatus according to claim 1 or 2 or 7

wherein the electrode transmits radio frequency energy.

13. An apparatus according to claim 1 or 2 or 7

wherein the processing element includes a neural network predictor.

14. An apparatus according to claim 1 or 2 or 7

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon fuzzy logic.

15. An apparatus according to claim 1 or 2 or 7

wherein the processing element processes changes in temperatures measured by the first and second sensing elements over time to derive the maximum tissue temperature prediction.

16. An apparatus according to claim 1 or 2 or 7

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon an analytical function f(T₁, T₂), where T₁ is the first temperature measured by the first sensing element and T₂ is the second temperature measured by the second sensing element.

17. An apparatus according to claim 1

wherein the electrode carries at least one of the first and second sensing elements.

18. An apparatus according to claim 17

wherein the at least one sensing element is carried within the electrode.

19. An apparatus according to claim 1

wherein at least one of the sensing elements is in thermal conductive contact with tissue.

20. An apparatus according to claim 1

wherein none of the sensing elements is in thermal conductive contact with tissue.

21. An apparatus according to claim 1

wherein at least one of the sensing elements is in thermal conductive contact with the electrode.

22. An apparatus according to claim 1 wherein at least one of the sensing elements is carried by the electrode within a carrier in thermal conductive contact with tissue.

23. An apparatus according to claim 22

wherein the carrier is made from a thermal conducting material having a high thermal conductivity that is at least 1.0 watt (W) per meter (m) Kelvin (K), or 1.0 W/m K.

24. An apparatus according to claim 1

and further including a second electrode spaced along a body from the first mentioned electrode, and

wherein the at least one of the sensing elements is located on the body between the first and second electrodes.

25. An apparatus according to claim 24

and further including a third temperature sensing element associated with the second electrode to measure a third temperature, and

wherein the processing element derives the maximum tissue temperature prediction from one or more temperatures measured by the first, second, and third sensing elements.

34. An apparatus according to claim 23

wherein the prescribed temperature remains essentially constant over time.

26. An apparatus for ablating body tissue comprising

an electrode for contacting a tissue region to transmit ablation energy,

a first sensing element for measuring temperature of the electrode,

a second sensing element for measuring temperature of tissue contacting the electrode, and

a processing element to process one or more temperatures measured by the first and second sensing elements and to derive therefrom a prediction of maximum temperature of the tissue region.

27. An apparatus according to claim 26

wherein the processing element generates an output based upon the maximum tissue temperature prediction.

28. An apparatus according to claim 27

wherein the processing element generates the output based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

29. An apparatus according to claims 28

wherein the prescribed temperature remains essentially constant over time.

30. An apparatus according to claim 28

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

31. An apparatus according to claims 28 or 29 or 30

wherein the processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to generate the output.

32. An apparatus according to claim 26

wherein the processing element controls the transmission of ablation energy by the electrode based, at least in part, upon the maximum tissue temperature prediction.

33. An apparatus according to claim 32

wherein the processing element controls the transmission of ablation energy based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

35. An apparatus according to claim 33

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

36. An apparatus according to claim 33 or 34 or 35

wherein the processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to control the transmission of ablation energy.

37. An apparatus according to claim 26 or 27 or 32

wherein the electrode transmits radio frequency energy.

38. An apparatus according to claim 26 or 27 or 32

wherein the processing element includes a neural network predictor.

39. An apparatus according to claim 26 or 27 or 32

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon fuzzy logic.

40. An apparatus according to claim 26 or 27 or 32

wherein the processing element processes changes in temperatures measured by the first and second sensing elements over time to derive the maximum tissue temperature prediction.

41. An apparatus according to claim 26 or 27 or 32

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon an analytical function f(T₁, T₂, where T₁ is temperature measured by the first sensing element and T₂ is temperature measured by the second sensing element.

42. An apparatus according to claim 26

wherein the electrode carries at least one of the first and second sensing elements.

43. An apparatus according to claim 42

wherein the at least one sensing element is carried within the electrode.

44. An apparatus according to claim 26

wherein the second sensing element is carried by the electrode within a carrier in thermal conductive contact with tissue.

45. An apparatus according to claim 44

wherein the carrier is made from a thermal conducting material having a high thermal conductivity that is at least 1.0 watt (W) per meter (m) Kelvin (K), or 1.0 W/m K.

46. An apparatus according to claim 26

and further including a second electrode spaced along a body from the first mentioned electrode, and

wherein the second sensing element is located on the body between the first and second electrodes.

47. An apparatus according to claim 46

and further including a third temperature sensing element to measure temperature of the second electrode.

48. An apparatus for transmitting energy to an electrode for heating tissue comprising

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

a controller coupled to the generator to supply power to the generator, the controller comprising

a first sensing element associated with the electrode for measuring a first temperature,

a second sensing element associated with the electrode for measuring a second temperature, and

a processing element to process one or more temperatures measured by the first and second sensing elements and to derive therefrom a prediction of maximum temperature of the tissue region and for generating a signal to control power supplied to the generator based, at least in part, upon the maximum tissue temperature prediction.

49. An apparatus according to claim 48

wherein the processing element controls the transmission of heating energy by the electrode based, at least in part, upon the maximum tissue temperature prediction.

50. An apparatus according to claim 49

wherein the processing element controls the transmission of heating energy based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

51. An apparatus according to claim 50

wherein the prescribed temperature remains essentially constant over time.

52. An apparatus according to claim 50

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

53. An apparatus according to claim 50 or 51 or 52

wherein the processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to control the transmission of heating energy.

54. An apparatus according to claim 48

wherein the electrode carries at least one of the first and second sensing elements.

55. An apparatus according to claim 54

wherein the at least one sensing element is carried within the electrode.

56. An apparatus according to claim 48

wherein at least one of the sensing elements is in thermal conductive contact with tissue.

57. An apparatus according to claim 48

wherein none of the sensing elements is in thermal conductive contact with tissue.

58. An apparatus according to claim 48

wherein at least one of the sensing elements is in thermal conductive contact with the electrode.

59. An apparatus according to claim 48 wherein at least one of the sensing elements is carried by the electrode within a carrier in thermal conductive contact with tissue.

60. An apparatus according to claim 59

wherein the carrier is made from a thermal conducting material having a high thermal conductivity that is at least 1.0 watt (W) per meter (m) Kelvin (K), or 1.0 W/m K.

61. An apparatus according to claim 48

and further including a second electrode spaced along a body from the first mentioned electrode, and least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to generate the output.

80. An apparatus according to claim 48 or 63

wherein the electrode transmits radio frequency energy.

81. An apparatus according to claim 48 or 63

wherein the processing element includes a neural network predictor.

82. An apparatus according to claim 48 or 63

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon fuzzy logic.

83. An apparatus according to claim 48 or 63

wherein the processing element processes changes in temperatures measured by the first and second sensing elements over time to derive the maximum tissue temperature prediction.

84. An apparatus according to claim 48 or 63

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon an analytical function f(T₁, T₂), where T₁ is the temperature measured by the first sensing element and T₂ is the temperature measured by the second sensing element.

74. An apparatus according to claim 63

wherein the electrode carries at least one of the first and second sensing elements.

75. An apparatus according to claim 74

wherein the at least one sensing element is carried within the electrode.

76. An apparatus according to claim 63

wherein the second sensing element is carried by the electrode within a carrier in thermal conductive contact with tissue.

77. An apparatus according to claim 76

wherein the carrier is made from a thermal conducting material having a high thermal conductivity that is at least 1.0 watt (W) per meter (m) Kelvin (K), or 1.0 W/m K.

78. An apparatus according to claim 63

and further including a second electrode spaced along a body from the first mentioned electrode, and

wherein the second sensing element is located on the body between the first and second electrodes.

79. An apparatus according to claim 78

and further including a third temperature sensing element to measure temperature of the second electrode.

85. A method for heating body tissue comprising

positioning an electrode to trannsmit heat energy to a tissue region,

measuring a first temperature using a temperature sensing element associated with the electrode,

measuring a second temperature using a temperature sensing element associated with the electrode, and

processing at least one of the first and second temperatures to derive a prediction of maximum temperature of the tissue region.

86. A method according to claim 85

and further including the step of generating an output based upon the maximum tissue temperature prediction.

87. A method according to claim 86

wherein the output is based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

88. A method according to claim 87

wherein the prescribed temperature remains essentially constant over time.

89. A method according to claim 87

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

90. A method according to claim 87 or 88 or 89

wherein the processing step applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to generate the output.

91. A method according to claim 85

wherein the processing element controls the transmission of heating energy by the electrode based, at least in part, upon the maximum tissue temperature prediction.

92. A method according to claim 91

wherein the processing element controls the transmission of heating energy based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

93. A method according to claim 92

wherein the prescribed temperature remains essentially constant over time.

94. A method according to claim 92

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

95. A method according to claim 92 or 93 or 94

wherein the processing element applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to control the transmission of heating energy.

96. A method according to claim 85

wherein the electrode transmits radio frequency energy.

97. A method according to claim 85

wherein the processing step includes a neural network predictor.

98. A method according to claim 85

wherein the processing step derives the maximum tissue temperature prediction based, at least in part, upon fuzzy logic.

99. A method according to claim 85

wherein the processing step processes changes in temperatures measured by the first and second sensing elements over time to derive the maximum tissue temperature prediction.

100. A method according to claim 85

wherein the processing element derives the maximum tissue temperature prediction based, at least in part, upon an analytical function f(T₁, T₂), where T₁ is the first temperature measured by the first sensing element and T₂ is the second temperature measured by the second sensing element.

101. A method for ablating body tissue comprising

placing an electrode in contact with a tissue region to transmit ablation energy,

measuring a first temperature of the electrode,

measuring a second temperature of tissue contacting the electrode, and

processing at least one of the first and second temperatures a prediction of maximum temperature of the tissue region.

102. A method according to claim 101

wherein the processing step generates an output based upon the maximum tissue temperature prediction.

103. A method according to claim 102

wherein the processing step generates the output based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

104. A method according to claim 103

wherein the prescribed temperature remains essentially constant over time.

105. A method according to claim 103

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

106. A method according to claim 103 or 104 or 105

wherein the processing step applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to generate the output.

107. A method according to claim 101

wherein the processing step controls the transmission of ablation energy by the electrode based, at least in part, upon the maximum tissue temperature prediction.

108. A method according to claim 107

wherein the processing step controls the transmission of ablation energy based upon comparing the maximum tissue temperature prediction to a prescribed temperature.

109. A method according to claim 108

wherein the prescribed temperature remains essentially constant over time.

110. A method according to claim 108

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

111. A method according to claim 108 or 109 or 110

wherein the processing atwp applies at least one proportional, derivative, or integral coefficient to the comparison of the maximum tissue temperature prediction to the prescribed temperature to control the transmission of ablation energy.

112. A method according to claim 101

wherein the electrode transmits radio frequency energy.

113. A method according to claim 101

wherein the processing step includes a neural network predictor.

114. A method according to claim 101

wherein the processing step derives the maximum tissue temperature prediction based, at least in part, upon fuzzy logic.

115. A method according to claim 101

wherein the processing step processes changes in temperatures measured by the first and second sensing elements over time to derive the maximum tissue temperature prediction.

116. A method according to claim 101

wherein the processing step derives the maximum tissue temperature prediction based, at least in part, upon an analytical function f(T₁, T₂), where T₁ is temperature measured by the first sensing element and T₂ is temperature measured by the second sensing element.