Methods for electrosurgical tissue treatment in conductive fluid

• US 6,416,508 B1
• Filed: 02/15/2000
• Issued: 07/09/2002
• Est. Priority Date: 05/10/1993
• Status: Expired due to Fees

• Current Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Original Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Inventors: Eggers, Philip E., Thapliyal, Hira V.
• Primary Examiner(s): COHEN, LEE S
• Application Number:
  US09/504,530
• Time in Patent Office: 875 Days
• Field of Search: 606/32, 606/41, 606/46, 606/49, 606/50, 606/34, 602/98, 602/99, 602/101, 602/105, 602/113, 604/114
• US Class Current: 606/32
• 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 body structure at a target site on or within a patient'"'"'s body, the method comprising:

positioning an active electrode into at least close proximity with a body structure at the target site in the presence of an electrically conductive fluid

positioning a return electrode within the electrically conductive fluid to generate a current flow path between the active and return electrodes; and

applying a high frequency voltage difference between the active and return electrodes such that an electrical current flows from the active electrode, through the target site, and to the return electrode, the high frequency voltage difference being in the range of about 500 to 1400 volts peak to peak.

2. The method of claim 1 wherein high frequency voltage is in the range of about 700 to 900 volts peak to peak.

3. The method of claim 1 further comprising spacing the return electrode from the body structure such that the return electrode does not contact any portion of the body structure.

4. The method of claim 1 further comprising vaporizing the electrically conductive fluid in a thin layer over at least a portion of the active electrode, contacting the body structure with the thin layer and inducing a discharge of energy to the body structure in contact with the thin layer.

5. The method of claim 4 further comprising ionizing the thin layer of vaporized fluid to form a plasma over at least a portion of the active electrode.

6. The method of claim 4 wherein at least a portion of the energy is in the form of energetic electrons.

7. The method of claim 1 further comprising generating a voltage gradient between the active electrode and the body structure at the target site, the voltage gradient being sufficient to create an electric field that causes the breakdown of tissue through molecular dissociation or disintegration.

8. The method of claim 1 wherein the return electrode is spaced a distance of about 0.5 to 10 mm from the body structure during the applying step.

9. The method of claim 1 wherein the return electrode is spaced a distance of about 1.0 to 5.0 mm from the body structure during the applying step.

10. The method of claim 1 further comprising introducing the electrically conductive fluid to the target site such that the active and return electrodes contact the electrically conductive fluid and the electrically conductive fluid completes a conductive path between the active and return electrodes.

11. The method of claim 1 wherein the electric current flows substantially through the electrically conductive fluid while minimizing electric current flow passing through the body structure.

12. The method of claim 1 wherein at least a portion of the electric current passes through the body structure.

13. The method of claim 1 wherein the active electrode comprises a single active electrode disposed near the distal end of an instrument shaft.

14. The method of claim 1 wherein the active electrode includes an array of electrically isolated active electrodes disposed near the distal end of an instrument shaft.

15. The method of claim 1 wherein the electrically conductive fluid comprises isotonic saline.

16. The method of claim 1 further comprising wherein the return electrode is spaced from the active electrode by an electrically insulating member comprising an inorganic material.

17. The method of claim 16 wherein the inorganic material is selected from the group consisting essentially of ceramic, glass and glass/ceramic compositions.

18. The method of claim 1 wherein the applying voltage step is carried out by applying power to the active electrode, wherein said power is controlled based on the electrical impedance between the active electrode and the return electrode.

19. The method of claim 18 further comprising limiting power to the active electrode when the electrical impedance is less than a threshold value.

20. The method of claim 1 wherein temperature at the target site is measured by a temperature sensor adjacent to the active electrode and power delivery to the active electrode is limited if the measured temperature exceeds a threshold value.

21. The method of claim 1 wherein the return electrode has a substantially greater exposed surface area than the active electrode.

22. The method of claim 1 wherein the return electrode has an exposed surface area at least 5 times greater than an exposed surface area of the active electrode.

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

positioning an active electrode into at least close proximity with a body structure at the target site in the presence of an electrically conductive fluid;

positioning a return electrode within the electrically conductive fluid to generate a current flow path between the active and return electrodes; and

applying a high frequency voltage difference between the active and return electrodes such that an electrical current flows from the active electrode, through the target site, and to the return electrode, the high frequency voltage being sufficient to cause the molecular breakdown of tissue cells in the body structure.

24. The method of claim 23 wherein the high frequency voltage difference is in the range of about 500 to 1400 volts peak to peak.

25. The method of claim 23 wherein the high frequency voltage is in the range of about 700 to 900 volts peak to peak.

26. The method of claim 23 further comprising spacing the return electrode from the body structure such that the return electrode does not contact any portion of the body structure.

27. The method of claim 23 further comprising vaporizing the electrically conductive fluid in a thin layer over at least a portion of the active electrode, contacting the body structure with the thin layer and inducing a discharge of energy to the body structure in contact with the thin layer.

28. The method of claim 27 further comprising ionizing the thin layer of vaporized fluid to form a plasma over at least a portion of the active electrode.

29. The method of claim 27 wherein at least a portion of the energy is in the form of energetic electrons.

30. The method of claim 23 further comprising generating a voltage gradient between the active electrode and the body structure at the target site, the voltage gradient being sufficient to create an electric field that causes the breakdown of tissue through molecular dissociation or disintegration.

31. The method of claim 23 wherein the return electrode is spaced a distance of about 0.5 to 10 mm from the body structure during the applying step.

32. The method of claim 23 wherein the return electrode is spaced a distance of about 1.0 to 5.0 mm from the body structure during the applying step.

33. The method of claim 23 further comprising introducing the electrically conductive fluid to the target site such that the active and return electrodes contact the electrically conductive fluid and the electrically conductive fluid completes a conductive path between the active and return electrodes.

34. The method of claim 23 wherein the electric current flows substantially through the electrically conductive fluid while minimizing electric current flow passing through the body structure.

35. The method of claim 23 wherein at least a portion of the electric current passes through the body structure.

36. The method of claim 23 wherein the active electrode comprises a single active electrode disposed near the distal end of an instrument shaft.

37. The method of claim 23 wherein the active electrode includes an array of electrically isolated active electrodes disposed near the distal end of an instrument shaft.

38. The method of claim 23 wherein the electrically conductive fluid comprises isotonic saline.

39. The method of claim 23 further comprising wherein the return electrode is spaced from the active electrode by an electrically insulating member comprising an inorganic material.

40. The method of claim 39 wherein the inorganic material is selected from the group consisting essentially of ceramic, glass and glass/ceramic compositions.

41. The method of claim 23 wherein the applying voltage step is carried out by applying power to the active electrode, wherein said power is controlled based on the electrical impedance between the active electrode and the return electrode.

42. The method of claim 41 further comprising limiting power to the active electrode when the electrical impedance is less than a threshold value.

43. The method of claim 23 wherein temperature at the target site is measured by a temperature sensor adjacent to the active electrode and power delivery to the active electrode is limited if the measured temperature exceeds a threshold value.

44. The method of claim 23 wherein the return electrode has a substantially greater exposed surface area than the active electrode.

45. The method of claim 23 wherein the return electrode has an exposed surface area at least 5 times greater than an exposed surface area of the active electrode.