Apparatus and method for creating, maintaining, and controlling a virtual electrode used for the ablation of tissue

• US 7,247,155 B2
• Filed: 05/18/2004
• Issued: 07/24/2007
• Est. Priority Date: 02/22/1995
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Goetz, Steven M., Christopherson, Mark A., Hoey, Michael F.
• Primary Examiner(s): Peffley; Michael
• Application Number:
  US10/847,979
• Publication Number:
  US 20040215183A1
• Time in Patent Office: 1,162 Days
• Field of Search: 606 27- 34, 606/41, 606/42, 607101-105
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/18 by applying electromagnetic radiation, e.g. microwaves radiation therapy A61N5/00
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2018/00029 open
• CPC Class Codes: A61B 2018/00196 reciprocating lengthwise
• CPC Class Codes: A61B 2018/00666 using a threshold value
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00708 switching the power on or off
• CPC Class Codes: A61B 2018/00779 Power or energy
• 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 2018/1213 creating an arc
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/1417 Ball
• CPC Class Codes: A61B 2018/1472 : for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2018/1475 : Electrodes retractable in or deployable from a housing
• CPC Class Codes: A61B 2218/002 : Irrigation
• CPC Class Codes: A61B 2218/007 : Aspiration

Abstract

The present invention provides an apparatus and a method for producing a virtual electrode within or upon a tissue to be treated with radio frequency alternating electric current, such tissues including but not limited to liver, lung, cardiac, prostate, breast, and vascular tissues and neoplasms. An apparatus in accord with the present invention includes a supply of a conductive or electrolytic fluid to be provided to the patient, an alternating current generator, and a processor for creating, maintaining, and controlling the ablation process by the interstitial or surficial delivery of the fluid to a tissue and the delivery of electric power to the tissue via the virtual electrode. A method in accord with the present invention includes delivering a conductive fluid to a predetermined tissue ablation site for a predetermined time period, applying a predetermined power level of radio frequency current to the tissue, monitoring at least one of several parameters, and adjusting either the applied power and/or the fluid flow in response to the measured parameters.

Claims

1. A method for treating tissue comprising:

providing radio frequency power at a power level;

providing a fluid at a fluid flow rate;

controlling the fluid flow rate based upon the power level; and

applying the radio frequency power with the fluid to treat the tissue from a surgical instrument.

2. The method of claim 1, wherein:

the fluid flow rate is controlled by use of an equation.

3. The method of claim 2, wherein:

the equation comprises a quadratic equation.

4. The method of claim 2, wherein:

the equation comprises a higher order equation.

5. The method of claim 1, wherein:

the fluid flow rate is controlled by use of a linear relationship.

6. The method of claim 1, wherein:

the fluid flow rate is controlled by use of a step relationship.

7. The method of claim 1, wherein:

the fluid flow rate is controlled by use of a look-up table.

8. The method of claim 1, wherein:

controlling the fluid flow rate based upon the power level is performed by a control apparatus comprising a microprocessor.

9. The method of claim 1, wherein:

the surgical instrument comprises a monopolar surgical instrument.

10. The method of claim 1, wherein:

the surgical instrument comprises a bipolar surgical instrument.

11. method of claim 1, wherein:

the radio frequency power is provided from a radio frequency power source, and

the radio frequency power source is configured to provide the radio frequency power in a power range between and including about 0.1 watts to about 200 watts.

12. The method of claim 11, wherein:

the radio frequency power source comprises a radio frequency generator.

13. The method of claim 11, wherein:

the radio frequency power source is configured to provide the radio frequency power at the power level in a frequency range between and including about 350 kHz to about 700 kHz and a resistive load range between and including about 10 ohms to about 500 ohms.

14. The method of claim 1, wherein:

the power level is provided in a range between and including about 0.1 watts to about 200 watts.

15. The method of claim 1, wherein:

the fluid flow rate is provided in a range between and including about 0.1 cubic centimeters per minute to about 10 cubic centimeters per minute.

16. The method of claim 1, wherein:

the fluid comprises at least one of an electrically conductive fluid and an electrolytic fluid.

17. The method of claim 1, wherein:

the fluid comprises at least one of an electrically conductive solution and an electrolytic solution.

18. The method of claim 1, wherein:

the fluid comprises saline.

19. The method of claim 1, wherein:

the fluid is provided from a fluid source comprising a container.

20. The method of claim 19, wherein:

the container comprises a flexible bag or a syringe.

21. The method of claim 1, wherein:

the radio frequency power is provided from a radio frequency power source;

the fluid is provided from a fluid source;

controlling the fluid flow rate based upon the power level is performed by a control apparatus comprising a microprocessor; and

the surgical instrument comprises an electrosurgical instrument in electrical communication with the radio frequency power source and in fluid communication with the fluid source, the electrosurgical instrument to provide the radio frequency power from the power source and the fluid from the fluid source to treat the tissue.

22. The method of claim 21, wherein:

the fluid flow rate used at the power level is stored in a memory.

23. The method of claim 21, wherein:

the electrosurgical instrument is in fluid communication with the fluid source via a fluid line.

24. The method of claim 23, wherein:

a pump is used to convey the fluid through the fluid line.

25. The method of claim 24, wherein:

the pump comprises a syringe pump.

26. The method of claim 24, wherein:

the pump comprises a flexible tube pump.

27. The method of claim 24, wherein:

the pump is configured to force the fluid out of the fluid source.

28. The method of claim 1, wherein:

the tissue comprises soft tissue.

29. The method of claim 1, wherein:

the tissue comprises bone tissue.

30. The method of claim 1, wherein:

the tissue comprises at least one of cardiac tissue, liver tissue, lung tissue, prostate tissue, breast tissue, organ tissue, vascular tissue and neoplasm tissue.

31. A method for treating tissue comprising:

providing radio frequency power at a power level;

providing a fluid at a fluid flow rate;

providing a relationship between the fluid flow rate and the power level; and

applying the radio frequency power with the fluid to treat the tissue from a surgical instrument.

32. The method of claim 31, wherein:

the relationship is provided by an equation.

33. The method of claim 32, wherein:

the equation comprises a quadratic equation.

34. The method of claim 32, wherein:

the equation comprises a higher order equation.

35. The method of claim 31, wherein:

the relationship comprises a linear relationship.

36. The method of claim 31, wherein:

the relationship comprises a step relationship.

37. The method of claim 31, wherein:

the relationship is provided by a look-up table.

38. The method of claim 31, further comprising:

the relationship between the fluid flow rate and the power level is used by a control apparatus comprising a microprocessor.

39. The method of claim 31, wherein:

the surgical instrument comprises a monopolar surgical instrument.

40. The method of claim 31, wherein:

the surgical instrument comprises a bipolar surgical instrument.

41. The method of claim 31, wherein:

the surgical instrument comprises a bipolar surgical instrument.

42. The method of claim 31, wherein:

the radio frequency power is provided from a radio frequency power source, and

the radio frequency power source is configured to provide the radio frequency power in a power range between and including about 0.1 watts to about 200 watts.

43. The method of claim 42, wherein:

the radio frequency power source comprises a radio frequency generator.

44. The method of claim 42, wherein:

the radio frequency power source is configured to provide the radio frequency power at the power level in a frequency range between and including about 350 kHz to about 700 kHz and a resistive load range between and including about 10 ohms to about 500 ohms.

45. The method of claim 31, wherein:

the power level is provided in a range between and including about 0.1 watts to about 200 watts.

46. The method of claim 31, wherein:

the fluid flow rate is provided in a range between and including about 0.1 cubic centimeters per minute to about 10 cubic centimeters per minute.

47. The method of claim 31, wherein:

the fluid comprises at least one of an electrically conductive fluid and an electrolytic fluid.

48. The method of claim 31, wherein:

the fluid comprises at least one of an electrically conductive solution and an electrolytic solution.

49. The method of claim 31, wherein:

the fluid comprises saline.

50. The method of claim 31, wherein:

the fluid is provided from a fluid source comprising a container.

51. The method of claim 50, wherein:

the container comprises a flexible bag or a syringe.

52. The method of claim 31, wherein:

the radio frequency power is provided from a radio frequency power source;

the fluid is provided from a fluid source;

the relationship between the fluid flow rate and the power level is used by a control apparatus comprising a microprocessor; and

the surgical instrument comprises an electrosurgical instrument in electrical communication with the radio frequency power source and in fluid communication with the fluid source, the electrosurgical instrument to provide the radio frequency power from the power source and the fluid from the fluid source to treat the tissue.

53. The method of claim 52, wherein:

the fluid flow rate used at the power level is stored in a memory.

54. The method of claim 52, wherein:

the electrosurgical instrument is in fluid communication with the fluid source via a fluid line.

55. The method of claim 54, wherein:

a pump is used to convey the fluid through the fluid line.

56. The method of claim 55, wherein:

the pump comprises a syringe pump.

57. The method of claim 55, wherein:

the pump comprises a flexible tube pump.

58. The method of claim 55 wherein:

the pump is configured to force the fluid out of the fluid source.

59. The method of claim 31, wherein:

the tissue comprises soft tissue.

60. The method of claim 31, wherein:

the tissue comprises bone tissue.

61. The method of claim 31, wherein:

the tissue comprises at least one of cardiac tissue, liver tissue, lung tissue, prostate tissue, breast tissue, organ tissue, vascular tissue and neoplasm tissue.

62. A method for treating tissue comprising:

providing radio frequency power at a power level;

providing a fluid at a fluid flow rate;

relating the fluid flow rate to the power level; and

applying the radio frequency power with the fluid to treat the tissue from a surgical instrument.

63. The method of claim 62, wherein:

the fluid flow rate is related by use of an equation.

64. The method of claim 63, wherein:

the equation comprises a quadratic equation.

65. The method of claim 63, wherein:

the equation comprises a higher order equation.

66. The method of claim 62, wherein:

the fluid flow rate is related by use of a linear relationship.

67. The method of claim 62, wherein:

the fluid flow rate is related by use of a step relationship.

68. The method of claim 62, wherein:

the fluid flow rate is related by use of a look-up table.

69. The method of claim 62, wherein:

relating the fluid flow rate to the power level is performed by a control apparatus comprising a microprocessor.

70. The method of claim 62, wherein:

the surgical instrument comprises a monopolar surgical instrument.

71. The method of claim 62, wherein:

the radio frequency power is provided from a radio frequency power source, and

the radio frequency power source is configured to provide the radio frequency power in a power range between and including about 0.1 watts to about 200 watts.

72. The method of claim 71, wherein:

the radio frequency power source comprises a radio frequency generator.

73. The method of claim 71, wherein:

the radio frequency power source is configured to provide the radio frequency power at the power level in a frequency range between and including about 350 kHz to about 700 kHz and a resistive load range between and including about 10 ohms to about 500 ohms.

74. The method of claim 62, wherein:

the power level is provided in a range between and including about 0.1 watts to about 200 watts.

75. The method of claim 62, wherein:

the fluid flow rate is provided in a range between and including about 0.1 cubic centimeters per minute to about 10 cubic centimeters per minute.

76. The method of claim 62, wherein:

the fluid comprises at least one of an electrically conductive fluid and an electrolytic fluid.

77. The method of claim 62, wherein:

the fluid comprises at least one of an electrically conductive solution and an electrolytic solution.

78. The method of claim 62, wherein:

the fluid comprises saline.

79. The method of claim 62, wherein:

the fluid is provided from a fluid source comprising a container.

80. The method of claim 79, wherein:

the container comprises a flexible bag or a syringe.

81. The method of claim 62, wherein:

the radio frequency power is provided from a radio frequency power source;

the fluid is provided from a fluid source;

relating the fluid flow rate to the power level is performed by a control apparatus comprising a microprocessor; and

the surgical instrument comprises an electrosurgical instrument in electrical communication with the radio frequency power source and in fluid communication with the fluid source, the electrosurgical instrument to provide the radio frequency power from the power source and the fluid from the fluid source to treat the tissue.

82. The method of claim 81, wherein:

the fluid flow rate used at the power level is stored in a memory.

83. The method of claim 81, wherein:

the electrosurgical instrument is in fluid communication with the fluid source via a fluid line.

84. The method of claim 83, wherein:

a pump is used to convey the fluid through the fluid line.

85. The method of claim 84, wherein:

the pump comprises a syringe pump.

86. The method of claim 84, wherein:

the pump comprises a flexible tube pump.

87. The method of claim 84, wherein:

the pump is configured to force the fluid out of the fluid source.

88. The method of claim 62, wherein:

the tissue comprises soft tissue.

89. The method of claim 62, wherein:

the tissue comprises bone tissue.

90. The method of claim 62, wherein:

the tissue comprises at least one of cardiac tissue, liver tissue, lung tissue, prostate tissue, breast tissue, organ tissue, vascular tissue and neoplasm tissue.

91. A method for treating tissue comprising:

providing radio frequency power at a power level;

providing a fluid at a fluid flow rate;

applying the radio frequency power with the fluid to treat the tissue from a surgical instrument; and

adjusting the fluid flow rate based upon the power level.

92. The method of claim 91, wherein:

the fluid flow rate is adjusted by use of an equation.

93. The method of claim 92, wherein:

the equation comprises a quadratic equation.

94. The method of claim 92, wherein:

the equation comprises a higher order equation.

95. The method of claim 91, wherein:

the fluid flow rate is adjusted by use of a linear relationship.

96. The method of claim 91, wherein:

the fluid flow rate is adjusted by use of a step relationship.

97. The method of claim 91, wherein:

the fluid flow rate is adjusted by use of a look-up table.

98. The method of claim 91, wherein:

adjusting the fluid flow rate based upon the power level is performed by a control apparatus comprising a microprocessor.

99. The method of claim 91, wherein:

the surgical instrument comprises a monopolar surgical instrument.

100. The method of claim 91, wherein:

the surgical instrument comprises a bipolar surgical instrument.

101. The method of claim 91, wherein:

the radio frequency power is provided from a radio frequency power source, and

the radio frequency power source is configured to provide the radio frequency power in a power range between and including about 0.1 watts to about 200 watts.

102. The method of claim 101, wherein:

the radio frequency power source comprises a radio frequency generator.

103. The method of claim 101, wherein:

the radio frequency power source is configured to provide the radio frequency power at the power level in a frequency range between and including about 350 kHz to about 700 kHz and a resistive load range between and including about 10 ohms to about 500 ohms.

104. The method of claim 91, wherein:

the power level is provided in a range between and including about 0.1 watts to about 200 watts.

105. The method of claim 91, wherein:

the fluid flow rate is provided in a range between and including about 0.1 cubic centimeters per minute to about 10 cubic centimeters per minute.

106. The method of claim 91, wherein:

the fluid comprises at least one of an electrically conductive fluid and an electrolytic fluid.

107. The method of claim 91, wherein:

the fluid comprises at least one of an electrically conductive solution and an electrolytic solution.

108. The method of claim 91, wherein:

the fluid comprises saline.

109. The method of claim 91, wherein:

the fluid is provided from a fluid source comprising a container.

110. The method of claim 109, wherein:

the container comprises a flexible bag or a syringe.

111. The method of claim 91, wherein:

the radio frequency power is provided from a radio frequency power source;

the fluid is provided from a fluid source;

adjusting the fluid flow rate based upon the power level is performed by a control apparatus comprising a microprocessor; and

the surgical instrument comprises an electrosurgical instrument in electrical communication with the radio frequency power source and in fluid communication with the fluid source, the electrosurgical instrument to provide the radio frequency power from the power source and the fluid from the fluid source to treat the tissue.

112. The method of claim 111, wherein:

the fluid flow rate used at the power level is stored in a memory.

113. The method of claim 111, wherein:

the electrosurgical instrument is in fluid communication with the fluid source via a fluid line.

114. The method of claim 113, wherein:

a pump is used to convey the fluid through the fluid line.

115. The method of claim 114, wherein:

the pump comprises a syringe pump.

116. The method of claim 114, wherein:

the pump comprises a flexible tube pump.

117. The method of claim 114, wherein:

the pump is configured to force the fluid out of the fluid source.

118. The method of claim 91, wherein:

the tissue comprises soft tissue.

119. The method of claim 91, wherein:

the tissue comprises bone tissue.

120. The method of claim 91, wherein:

the tissue comprises at least one of cardiac tissue, liver tissue, lung tissue, prostate tissue, breast tissue, organ tissue, vascular tissue and neoplasm tissue.

121. A system for treating tissue comprising:

a radio frequency power source to provide radio frequency power;

a fluid source to provide a fluid;

an electrosurgical instrument connectable to the radio frequency power source and the fluid source, the electrosurgical instrument to provide the radio frequency power from the power source and the fluid from the fluid source to treat the tissue; and

a control apparatus to control a fluid flow rate of the fluid based upon a power level of the radio frequency power.

122. The system of claim 121, wherein:

the control apparatus comprises a microprocessor.

123. The system of claim 122, further comprising:

a pump.

124. The system of claim 123, wherein:

the pump, the microprocessor and the power source are contained in a single housing.

125. The system of claim 124, wherein:

the housing further contains the fluid source.

126. A system for treating tissue comprising:

a radio frequency power source to provide radio frequency power;

a fluid source to provide a fluid;

an electrosurgical instrument connectable to the radio frequency power source and the fluid source, the electrosurgical instrument to provide the fluid from the fluid source and the radio frequency power from the power source to treat the tissue; and

a control apparatus to provide a relationship between a fluid flow rate of the fluid and a power level of the radio frequency power.

127. The system of claim 126, wherein:

the control apparatus comprises a microprocessor.

128. The system of claim 127, further comprising:

a pump.

129. The system of claim 128, wherein:

the pump, the microprocessor and the power source are contained in a single housing.

130. The system of claim 129, wherein:

the housing further contains the fluid source.

131. A system for treating tissue comprising:

a radio frequency power source to provide radio frequency power;

a fluid source to provide a fluid;

an electrosurgical instrument connectable to the radio frequency power source and the fluid source, the electrosurgical instrument to provide the fluid from the fluid source and the radio frequency power from the power source to treat the tissue; and

a control apparatus to provide a fluid flow rate of the fluid in relation to a power level of the radio frequency power.

132. The system of claim 131, wherein:

the control apparatus comprises a microprocessor.

133. The system of claim 132, further comprising:

a pump.

134. The system of claim 133, wherein:

the pump, the microprocessor and the power source are contained in a single housing.

135. The system of claim 134, wherein:

the housing further contains the fluid source.

136. A system for treating tissue comprising:

a radio frequency power source to provide radio frequency power;

a fluid source to provide a fluid;

an electrosurgical instrument connectable to the radio frequency power source and the fluid source, the electrosurgical instrument to provide the fluid from the fluid source and the radio frequency power from the power source to treat the tissue; and

a control apparatus to adjust a fluid flow rate of the fluid based upon a power level of the radio frequency power.

137. The system of claim 136, wherein:

the control apparatus comprises a microprocessor.

138. The system of claim 137, further comprising:

a pump.

139. The system of claim 138, wherein:

the pump, the microprocessor and the power source are contained in a single housing.

140. The system of claim 139, wherein:

the housing further contains the fluid source.