Systems for electrosurgical tissue treatment in conductive fluid

• US 20040087937A1
• Filed: 06/24/2003
• Published: 05/06/2004
• Est. Priority Date: 05/10/1994
• Status: Active Grant

• Current Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Original Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Inventors: Eggers, Philip E., Thapliyal, Hira V.
• Granted Patent: US 7,217,268 B2
• Time in Patent Office: Days
• US Class Current: 606/41
• CPC Class Codes: A61B 18/042 using additional gas becoming plasma
• 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 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 18/1482 having a long rigid shaft for accessing the inner body transcutaneously in minimal invasive surgery, e.g. laparoscopy
• CPC Class Codes: A61B 18/1485 having a short rigid shaft for accessing the inner body through natural openings
• CPC Class Codes: A61B 18/149 bow shaped or with rotatable body at cantilever end, e.g. for resectoscopes, or coagulating rollers
• 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 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/00097 one of the thermometric elements being an electrode or the heating element
• CPC Class Codes: A61B 2017/00101 using an array of thermosensors
• CPC Class Codes: A61B 2017/00106 ultrasonic
• CPC Class Codes: A61B 2017/00247 Making holes in the wall of the heart, e.g. laser Myocardial revascularization
• CPC Class Codes: A61B 2017/00292 mounted on or guided by flexible, e.g. catheter-like, means
• CPC Class Codes: A61B 2017/003 Steerable
• CPC Class Codes: A61B 2017/22001 Angioplasty, e.g. PCTA
• CPC Class Codes: A61B 2017/22038 with a guide wire
• CPC Class Codes: A61B 2018/00029 open
• CPC Class Codes: A61B 2018/00083 : low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00119 : with metal oxide nitride
• CPC Class Codes: A61B 2018/0016 : Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00178 : Electrical connectors
• CPC Class Codes: A61B 2018/00196 : reciprocating lengthwise
• CPC Class Codes: A61B 2018/00327 : Ear, nose or throat
• CPC Class Codes: A61B 2018/00392 : Transmyocardial revascularisation
• CPC Class Codes: A61B 2018/0047 : Upper parts of the skin, e.g. skin peeling or treatment of wrinkles
• CPC Class Codes: A61B 2018/00476 : Hair follicles
• CPC Class Codes: A61B 2018/00505 : Urinary tract
• CPC Class Codes: A61B 2018/00577 : Ablation
• CPC Class Codes: A61B 2018/00583 : Coblation, i.e. ablation using a cold plasma
• CPC Class Codes: A61B 2018/00601 : Cutting
• CPC Class Codes: A61B 2018/00642 : with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/0066 : without feedback, i.e. open loop control
• CPC Class Codes: A61B 2018/00678 : upper
• CPC Class Codes: A61B 2018/00702 : Power or energy
• CPC Class Codes: A61B 2018/00726 : Duty cycle
• CPC Class Codes: A61B 2018/00738 : Depth, e.g. depth of ablation
• CPC Class Codes: A61B 2018/00755 : Resistance or impedance
• 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 2018/00821 : measured by a thermocouple
• CPC Class Codes: A61B 2018/00827 : Current
• CPC Class Codes: A61B 2018/00875 : Resistance or impedance
• CPC Class Codes: A61B 2018/00886 : Duration
• CPC Class Codes: A61B 2018/00982 : combined with or comprising means for visual or photographic inspections inside the body, e.g. endoscopes
• CPC Class Codes: A61B 2018/1213 : creating an arc
• CPC Class Codes: A61B 2018/124 : switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/1246 : characterised by the output polarity
• CPC Class Codes: A61B 2018/1253 : monopolar
• CPC Class Codes: A61B 2018/126 : bipolar
• CPC Class Codes: A61B 2018/1273 : including multiple generators in one device
• CPC Class Codes: A61B 2018/1407 : Loop
• CPC Class Codes: A61B 2018/1467 : using more than two electrodes on a single probe
• CPC Class Codes: A61B 2018/1472 : for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2018/162 : located on the probe body
• CPC Class Codes: A61B 2018/165 : Multiple indifferent electrodes
• CPC Class Codes: A61B 2090/378 : using ultrasound
• CPC Class Codes: A61B 2090/3782 : transmitter or receiver in catheter or minimal invasive instrument
• CPC Class Codes: A61B 2218/002 : Irrigation
• CPC Class Codes: A61B 2218/007 : Aspiration
• CPC Class Codes: A61F 2/2493 : Transmyocardial revascularisation [TMR] devices
• CPC Class Codes: A61F 2/95 : Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61M 25/0133 : Tip steering devices
• CPC Class Codes: A61M 25/0147 : with movable mechanical means, e.g. pull wires
• CPC Class Codes: A61M 25/0158 : with magnetic or electrical means, e.g. by using piezo materials, electroactive polymers, magnetic materials or by heating of shape memory materials

Abstract

An electrosurgical probe (10) comprises a shaft (13) having an electrode array (58) at its distal end and a connector (19) at its proximal end for coupling the electrode array to a high frequency power supply (28). The shaft includes a return electrode (56) recessed from its distal end and enclosed within an insulating jacket (18). The return electrode defines an inner passage (83) electrically connected to both the return electrode and the electrode array for passage of an electrically conducting liquid (50). By applying high frequency voltage to the electrode array and the return electrode, the electrically conducting liquid generates a current flow path between the return electrode and the electrode array so that target tissue may be cut or ablated. The probe is particularly useful in dry environments, such as the mouth or abdominal cavity, because the electrically conducting liquid provides the necessary return current path between the active and return electrodes.

Claims

1. A method for applying electrical energy to a target site on a structure within a patient'"'"'s body, the method comprising:

positioning an active electrode into at least close proximity with the target site in the presence of an electrically conducting liquid;

positioning a return electrode within the electrically conducting liquid to generate a current flow path between the target site and the return electrode; and

applying high frequency voltage to the active electrode and the return electrode such that an electrical current flows from the active electrode, through the body structure in the region of the target site, and to the return electrode through the current flow path.

2. The method of claim 1 further comprising directing an electrically conducting liquid along a fluid path past the return electrode and to the target site to generate the current flow path between the target site and the return electrode.

3. The method of claim 1 further comprising immersing the target site within a supply of the electrically conductive liquid and positioning the return electrode within the supply of electrically conductive liquid to generate the current flow path between the target site and the return electrode.

4. The method of claim 2 further comprising generating a high electric field intensity at a distal portion of the active electrode.

5. The method of claim 2 wherein the active electrode is introduced into a substantially dry body cavity so that the target site is substantially electrically isolated from the return electrode prior to the directing step.

6. The method of claim 5 further including pressurizing the body cavity with a gas.

7. The method of claim 6 wherein the body cavity is the patient'"'"'s abdomen.

8. The method of claim 5 wherein the body cavity is the patient'"'"'s mouth.

9. The method of claim 2 wherein the active electrode is introduced through a percutaneous penetration in the patient.

10. The method of claim 9 wherein the active electrode is introduced into the thoracic cavity via a flexible catheter.

11. The method of claim 3 wherein the active electrode is introduced into a cavity in the patient'"'"'s body flooded with the electrically conducting liquid.

12. The method of claim 1 wherein the active electrode is positioned in close proximity to a target site on the epidermis of the patient.

13. The method of claim 2 wherein the directing step includes supplying the electrically conductive liquid to a proximal end of an axial lumen defined by the return electrode within a probe and directing the liquid through a distal end of the axial lumen to the active electrode.

14. The method of claim 1 further including positioning a distal end of a liquid supply shaft adjacent the active electrode, the directing step including directing the electrically conducting liquid through an inner lumen in the liquid supply shaft that is electrically connected to the return electrode and discharging the liquid through an open distal end of the supply shaft towards the active electrode.

15. The method of claim 1 wherein the active electrode comprises an electrode array including a plurality of isolated electrode terminals.

16. The method of claim 1 wherein the electrically conducting fluid has a conductivity greater than 2 mS/cm.

17. The method of claim 2 wherein the electrically conductive liquid comprises isotonic saline.

18. The method of claim 4 wherein the electric field intensity is sufficient to cause molecular disintegration of tissue structure on the target site.

19. The method of claim 15 including independently controlling current flow from at least two of the electrode terminals based on impedance between the electrode terminal and the return electrode.

20. The method of claim 15 wherein the return electrode is an outer tubular member, the shaft including an insulating member defining an axial passage between the insulating member and the outer tubular member, the directing step including directing the electrically conductive liquid through the inner lumen to the distal end of the shaft over the active electrode.

21. A method as in claim 15, further including maintaining a space between the electrode array and the body structure, during the applying step.

22. The method of claim 21 wherein the maintain step comprises moving the electrode array transversely across the body structure.

23. A method for applying energy to a target site on a patient body structure comprising:

positioning an active electrode surface in close proximity to the target site in the presence of an electrically conducting liquid; and

applying a high frequency voltage between the active electrode surface and a return electrode surface, the high frequency voltage being sufficient to vaporize the liquid in a thin layer over at least a portion of the active electrode surface and induce the discharge of energy from the vapor layer.

24. The method of claim 23 wherein the active electrode surface comprises an electrode array including a plurality of isolated electrode terminals.

25. The method of claim 23 wherein the at least a portion of the energy induced from the vapor layer is in the form of photons having a wavelength in the ultraviolet spectrum.

26. The method of claim 23 wherein at least a portion of the energy induced from the vapor layer is in the form of energetic electrons.

27. The method of claim 24 wherein the isolated electrode terminals each have a contact area below 15 mm².

28. The method of claim 24 wherein the isolated electrode terminals have circular contact surfaces with an area in the range from 0.01 mm² to 1 mm².

29. The method of claim 24 wherein the electrode surface includes at least two electrode terminals.

30. The method of claim 24 wherein the electrode surface comprises between 4 to 50 electrode terminals.

31. The method of claim 24 wherein the electrode terminals are spaced from each other a distance of 5 to 0.01 mm.

32. The method of claim 24 wherein the electrode array is disposed over a distal tip of an electrosurgical probe.

33. The method of claim 32 wherein the distal tip of the probe includes an insulating matrix between the electrode terminals, the insulating matrix comprising a material having a relatively low thermal conductivity.

34. The method of claim 24 wherein the electrode terminals comprises a material with a relatively low thermal conductivity.

35. The method of claim 34 wherein the electrode materials comprises a material selected from the group consisting of titanium, tungsten, platinum, aluminum and tantalum.

36. The method of claim 32 wherein the electrode terminals extend a distance of 0.00 to 5 mm from an electrically insulating matrix on the distal tip of the probe.

37. The method of claim 32 wherein the electrode terminals are substantially flush with an electrically insulating matrix on the distal tip of the probe.

38. The method of claim 32 wherein the electrode terminals are proximally recessed a distance of 0.00 to 0.005 inches from an electrically insulating matrix on the distal tip of the probe.

39. The method of claim 23 wherein the high frequency voltage is at least 300 volts peak to peak.

40. The method of claim 23 wherein the voltage is in the range from 600 to 1400 volts peak to peak.

41. The method of claim 23 wherein the active electrode is positioned between 0.02 to 5 mm from the target site.

42. The method of claim 23 wherein the vapor layer has a thickness of 10 to 400 microns.

43. The method of claim 23 wherein the active electrode surface and the return electrode surface are spaced apart by a distance in the range from 1 to 10 mm.

44. The method of claim 24 wherein the return electrode has a distal end positioned proximal to the electrode array.

45. The method of claim 23 wherein the active electrode surface and the return electrode comprise a bipolar array of isolated electrode terminals.

46. The method of claim 23 wherein the electrically conducting liquid has a conductivity greater than 2 mS/cm.

47. The method of claim 23 wherein the electrically conductive liquid comprises isotonic saline.

48. A method for applying energy to a target site on a patient body structure comprising:

positioning an active electrode surface in close proximity to the target site in the presence of an electrically conducting liquid; and

applying a high frequency voltage between the active electrode surface and a return electrode surface, the high frequency voltage being sufficient to impart sufficient energy into the target site to ablate several cell layers of the body structure without causing substantial tissue necrosis beyond the several cell layers.

49. The method of claim 48 wherein the applying step comprises:

vaporizing the electrically conducting liquid in a thin layer over at least a portion of the active electrode surface; and

inducing the discharge of photons from the vapor layer.

50. The method of claim 48 wherein the applying step comprises:

vaporizing the electrically conducting liquid in a thin layer over at least a portion of the active electrode surface; and

inducing the discharge of energetic electrons from the vapor layer.

51. The method of claim 48 wherein the depth of necrosis is 0 to 400 microns.

52. A method for applying energy to a target site on a patient body structure comprising:

positioning an active electrode surface in close proximity to the target site in the presence of an electrically conducting liquid; and

applying a high frequency voltage between the active electrode surface and a return electrode surface, the high frequency voltage being in the range from 600 to 1400 volts peak to peak.

53. The method of claim 52 wherein the high frequency voltage is in the range from 700 to 900 volts peak to peak.

54. A method for applying energy to a target site on a patient body structure comprising:

positioning an active electrode surface in close proximity to the target site in the presence of an electrically conducting liquid; and

generating a voltage gradient between the active electrode surface and tissue at the target site, the voltage gradient being sufficient to create an electric field that breaks down the tissue through molecular dissociation.

55. The method of claim 54 wherein the generating step comprises:

applying a high frequency voltage between the active electrode surface and a return electrode surface; and

vaporizing the electrically conducting liquid in a thin layer over at least a portion of the active electrode surface.

56. The method of claim 55 further comprising developing a film layer of vapor between the active electrode and the tissue at the target site.

57. The method of claim 56 wherein a substantial portion of the voltage drop occurs across the film layer of vapor to shield the tissue from the high frequency voltage.

58. The method of claim 55 further comprising cooling the tissue with the electrically conducting liquid to shield the tissue from the high frequency voltage.

59. The method of claim 58 wherein the cooling step includes translating the distal tip of the probe over the target site to allow the electrically conducting liquid to contact the tissue after the tissue has been subjected to the high frequency voltage.

60. An electrosurgical system for use with a high frequency power supply and an electrically conducting liquid supply, the system comprising:

an electrosurgical probe comprising a shaft having a proximal end and a distal end, an active electrode disposed near the distal end, and a connector near the proximal end of the shaft for electrically coupling the active electrode to the electrosurgical power supply; and

a return electrode adapted to be electrically coupled to the electrosurgical power supply;

wherein the active and return electrodes are configured, upon the application of a sufficiently high frequency voltage therebetween, to vaporize the liquid in a thin layer over at least a portion of the active electrode and induce the discharge of energy from the vapor layer.

61. The system of claim 60 wherein the energy induced from the thin layer of vaporized liquid is in the form of energetic electrons.

62. The system of claim 60 wherein the energy induced from the thin layer of vaporized liquid is in the form of photons having a wavelength in the ultraviolet spectrum.

63. The system of claim 60 wherein the return electrode defines a liquid path in electrical contact with the return electrode and the active electrode, the liquid path having an inlet adapted to be fluidly coupled to the electrically conductive liquid supply for generating a current flow path between the return electrode and the active electrode.

64. The system of claim 60 wherein the active electrode comprises an electrode array including a plurality of isolated electrode terminals.

65. The system of claim 64 wherein the isolated electrode terminals each have a contact area below 15 mm².

66. The system of claim 64 wherein the electrode surface includes at least two electrode terminals.

67. The system of claim 64 wherein the electrode surface comprises between 4 and 50 electrode terminals.

68. The system of claim 64 wherein the electrode terminals are spaced from each other a distance of 0.01 to 5 mm.

69. The system of claim 64 wherein the electrode array is disposed over a distal tip of an electrosurgical probe.

70. The system of claim 69 wherein the distal tip of the probe includes an insulating matrix between the electrode terminals, the insulating matrix comprising a material having a relatively low thermal conductivity.

71. The system of claim 64 wherein the electrode terminals comprises a material with a relatively low thermal conductivity.

72. The system of claim 71 wherein the electrode materials comprises a material selected from the group consisting of titanium, tungsten, platinum, aluminum and tantalum.

73. The system of claim 64 wherein the electrode terminals extend a distance of 0.0 to 5 mm from an electrically insulating matrix on the distal tip of the probe.

74. The system of claim 64 wherein the electrode terminals are substantially flush with an electrically insulating matrix on the distal tip of the probe.

75. The system of claim 64 wherein the electrode terminals are proximally recessed a distance of 0.0 to 5 mm from an electrically insulating matrix on the distal tip of the probe.

76. The system of claim 61 wherein the high frequency voltage is at least 300 volts peak to peak.

77. The system of claim 60 wherein the voltage is in the range from 600 to 1400 volts peak to peak.

78. The system of claim 60 wherein the electrically conducting liquid has a conductivity greater than 2 mS/cm.

79. The system of claim 60 wherein the electrically conductive liquid comprises isotonic saline.