Electrosurgical probe for treating tissue in electrically conductive fluid

• US 6,312,408 B1
• Filed: 12/05/1996
• Issued: 11/06/2001
• Est. Priority Date: 01/07/1992
• 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): SEIDEL, RICHARD K
• Application Number:
  US08/761,096
• Time in Patent Office: 1,797 Days
• Field of Search: 604/22, 604/99, 604/164, 604/114, 601/2, 606/39, 606/32, 606/45, 606/47, 606/48, 606/27-29, 607/96, 607/113, 607/115, 607/116, 607/138, 607/156
• US Class Current: 604/114
• 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 2017/00247 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 2018/0016 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 2018/00392 : Transmyocardial revascularisation
• 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 2018/00726 : Duty cycle
• 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 2018/1213 : creating an arc
• 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 2018/1407 : 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 2090/378 : using ultrasound
• 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: 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
• CPC Class Codes: A61N 1/05 : for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/403 : for thermotherapy, e.g. hyperthermia

Abstract

An electrosurgical probe includes a shaft having an electrode array at its distal end and a connector at its proximal end. The array includes a plurality of isolated electrode terminals, and an electrosurgical power supply is provided with a multiplicity of independently limited or controlled current sources and a connector. The electrosurgical probe and the power supply may be connected through their respective connectors so that the independent current sources are connected to individual electrode terminals. By applying very high frequency electrical energy to the electrode array, target tissue may be cut or ablated while heat dissipation through low impedence paths, such as blood and normal saline, will be minimized.

Claims

1. An electrosurgical probe for applying electrical energy to a tissue structure at a target site, the probe comprising:

a shaft having a proximal end and a distal end;

an electrode terminal having a tissue treatment portion disposed at or near the distal end of the shaft;

a return electrode coupled to the shaft and having an exposed fluid contact surface;

at least one connector disposed near the proximal end of the shaft for electrically coupling the electrode terminal to a high frequency voltage source; and

wherein the return electrode is spaced from the electrode terminal such that when the tissue treatment portion of the electrode terminal is brought adjacent a tissue structure immersed in electrically conductive fluid, the tissue treatment portion of the electrode terminal is positioned between the fluid contact surface of the return electrode and the tissue structure and the electrically conductive fluid completes a conduction path between the electrode terminal and the return electrode.

2. The probe of claim 1 wherein the return electrode is spaced about 0.5 to 25 mm from the electrode terminal in a direction away from the tissue structure when the electrode terminal is brought adjacent a tissue structure.

3. The probe of claim 1 wherein the return electrode is positioned on the shaft proximal to the electrode terminal.

4. The probe of claim 1 further comprising a power limiting element coupled to the electrode terminal for limiting power to the electrode terminal based on the electrical impedance between the electrode terminal and the return electrode.

5. The probe of claim 1 wherein the electrode terminal extends a distance of about 0.05 to about 1.0 mm from the shaft.

11. The probe of claim 1, further comprising a temperature sensor located adjacent the electrode terminal wherein the connector also electrically couples the temperature sensor to the high frequency voltage source.

12. The probe of claim 1, wherein the electrode terminal is spaced from the shaft by a distance in the range from 0.00 mm to 3.0 mm.

13. The probe of claim 1 further comprising an electrode array disposed at the distal end of the shaft, the electrode array comprising a plurality of electrode terminals.

14. The probe of claim 1, further comprising an insulating support positioned near the distal end of the probe between the return electrode and the electrode terminal and comprising an inorganic matrix material.

15. The probe of claim 14 wherein the inorganic matrix material is selected from the group consisting essentially of glass, ceramic and glass/ceramic.

16. The probe of claim 13 wherein the electrode array includes at least three electrically isolated terminals having substantially the same applied potential.

17. The probe of claim 13 wherein the electrode array includes at least five electrically isolated terminals having substantially the same applied potential.

18. The probe of claim 1 further comprising a single active electrode terminal, wherein the single active electrode terminal and the return electrode are configured to effect the electrical breakdown of tissue in the immediate vicinity of the electrode terminal when high frequency voltage is applied between the electrode terminal and the return electrode in the presence of electrically conducting fluid.

19. The probe of claim 4 wherein current or voltage is limited to the electrode terminal based on impedance between the electrode terminal and the return electrode.

20. The probe of claim 1 further comprising an active current limiting element coupled to the electrode terminal and comprising an impedance sensor adapted for coupling to a high frequency voltage source.

21. The probe of claim 20 wherein the impedance sensor comprises means for measuring current flow for a given applied voltage.

22. The probe of claim 20 wherein the impedance sensor comprises a resonant series output circuit having a resonant frequency that changes with the capacitance of the load.

23. The probe of claim 1 further comprising a passive current limiting element for limiting or interrupting current flow to the electrode terminal based on the impedance between the electrode terminal and the return electrode.

24. The probe of claim 23 wherein the passive current limiting element is selected from the group consisting essentially of inductors, capacitors, resistors and combinations thereof.

25. The probe of claim 1 wherein the return electrode and the electrode terminal are positioned relative to each other such that the conduction path passes through the tissue structure at the target site.

26. The probe of claim 1 wherein the return electrode and the electrode terminal are positioned relative to each other such that the conduction path passes directly from the electrode terminal through the electrically conductive fluid to the return electrode.

6. An electrosurgical system for applying electrical energy to a tissue structure at a target site, the system comprising:

a shaft having a proximal end and a distal end;

an electrode terminal disposed at or near the distal end of the shaft;

at least one connector disposed near the proximal end of the shaft for electrically coupling the electrode terminal to a high frequency voltage source; and

means for applying high frequency voltage to the electrode terminal and a return electrode in the presence of electrically conducting fluid such that an electrical current flows from the electrode terminal, and through the target site, to the return electrode through a current flow path in the electrically conducting fluid.

7. The system of claim 6 wherein said applying means comprises a power supply, and a return electrode on the shaft spaced from the electrode terminal.

8. The system of claim 7 wherein the electrode terminal comprises tungsten, and further comprising a ceramic insulating member between the electrode terminal and the return electrode.

9. The system of claim 7 wherein the return electrode has a larger exposed surface area than the electrode terminal.

10. The system of claim 7 wherein the return electrode is axially spaced about 1 to 5 mm from the electrode terminal.

27. The system of claim 7 wherein the return electrode is spaced about 0.5 to 10 mm from the electrode terminal.

28. The system of claim 7 wherein the power supply applies a high frequency voltage difference in the range of about 500 to 900 volts peak-to-peak.

29. The system of claim 6 wherein the electrode terminal has a contact area less than about 5 mm².

30. The system of claim 6, wherein the electrode terminal is spaced from the shaft by a distance in the range from 0.00 mm to 3.0 mm.

31. The system of claim 6 further comprising an electrode array disposed at the distal end of the shaft, the electrode array comprising a plurality of electrode terminals.

32. The system of claim 7, further comprising an insulating support positioned near the distal end of the probe between the return electrode and the electrode terminal and comprising an inorganic matrix material, and wherein the inorganic matrix material is selected from the group consisting essentially of glass, ceramic and glass/ceramic.

33. The system of claim 7 further comprising a single active electrode terminal, wherein the single active electrode terminal and the return electrode are configured to effect the electrical breakdown of tissue in the immediate vicinity of the electrode terminal when high frequency voltage is applied between the electrode terminal and the return electrode in the presence of electrically conducting fluid.

34. The system of claim 6 wherein current or voltage is limited to the electrode terminal based on impedance between the electrode terminal and a return electrode spaced therefrom.

35. The system of claim 7 wherein the return electrode and the electrode terminal are positioned relative to each other such that the conduction path passes through the tissue structure at the target site.

36. The system of claim 7 wherein the return electrode and the electrode terminal are positioned relative to each other such that the conduction path passes directly from the electrode terminal through the electrically conductive fluid to the return electrode.