System and methods for electrosurgical tissue treatment in the presence of electrically conductive fluid

• US 6,149,620 A
• Filed: 02/12/1999
• Issued: 11/21/2000
• Est. Priority Date: 11/22/1995
• Status: Expired due to Term

• Current Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Original Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Inventors: Woloszko, Jean, Eggers, Philip E., Thapliyal, Hira V., Baker, Michael A., Underwood, Ronald A., Brunell, Stephen M.
• Primary Examiner(s): Yasko, John D.
• Assistant Examiner(s): MENDEZ, MANUEL A
• Application Number:
  US09/248,763
• Time in Patent Office: 648 Days
• Field of Search: 604/22, 604/43, 604/48, 604/113, 604/114, 604/264, 604/271, 604/280, 607/27-32, 607/35, 607/38, 607/41
• US Class Current: 604/22
• 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 2018/00505 : Urinary tract
• CPC Class Codes: A61B 2018/00565 : Bone
• 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

Abstract

Systems and methods are provided for applying a high frequency voltage in the presence of an electrically conductive fluid to create a relatively low-temperature plasma for ablation of tissue adjacent to, or in contact with, the plasma. In one embodiment, an electrosurgical probe or catheter is positioned adjacent the target site so that one or more active electrode(s) are brought into contact with, or close proximity to, a target tissue in the presence of electrically conductive fluid. High frequency voltage is then applied between the electrode terminal(s) and one or more return electrode(s) to generate a plasma adjacent to the active electrode(s), and to volumetrically remove or ablate at least a portion of the target tissue. The high frequency voltage generates electric fields around the active electrode(s) with sufficient energy to ionize the conductive fluid adjacent to the active electrode(s). Within the ionized gas or plasma, free electrons are accelerated, and electron-atoms collisions liberate more electrons, and the process cascades until the plasma contains sufficient energy to break apart the tissue molecules, causing molecular dissociation and ablation of the target tissue.

Claims

1. A method for applying electrical energy to tissue comprising:

positioning an active electrode adjacent to or in contact with tissue in the presence of electrically conductive fluid;

applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to generate a plasma adjacent to the active electrode; and

effecting ablation of at least a portion of the tissue.

2. The method of claim 1 further comprising generating electric fields adjacent the active electrode, the electric fields having sufficient energy to generate the plasma.

3. The method of claim 1 further comprising vaporizing a portion of the electrically conductive fluid adjacent to the active electrode.

4. The method of claim 1 wherein the effecting ablation step is carried out by contacting the tissue with the plasma.

5. The method of claim 1 wherein the effecting ablation step is carried out by generating the plasma at a location spaced from the tissue.

6. The method of claim 5 wherein the plasma is generated at a location spaced a distance of about 0.05 to 5 mm from the tissue, the method further comprising the step of accelerating ions from the plasma such that the ions contact the tissue.

7. The method of claim 1 further comprising positioning the return electrode within the electrically conductive fluid such that electrically conductive fluid forms a current flow path between the active and return electrodes.

8. The method of claim 1 further comprising directing the electrically conductive fluid along a fluid path in contact with the active and return electrodes.

9. The method of claim 1 further comprising applying a sufficient high frequency voltage difference between the active and return electrodes to generate energy of at least 3.5 eV within or around the plasma.

10. The method of claim 1 further comprising applying a sufficient high frequency voltage difference between the active and return electrodes to generate energy of at least 4.0 eV within or around the plasma.

11. A method for applying electrical energy to tissue comprising:

positioning an active electrode adjacent to or in contact with tissue in the presence of electrically conductive fluid;

applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to vaporize a portion of the electrically conductive fluid such that the vaporized fluid has a temperature below 100°

C.; and

effecting ablation of at least a portion of the tissue in contact with the vaporized fluid .

12. The method of claim 11 wherein the electrically conductive fluid is vaporized at a subatmospheric pressure.

13. The method of claim 11 wherein said electrically conductive fluid has a boiling temperature below 100°

C. at 1 atmosphere pressure.

14. The method of claim 11 further comprising applying a sufficient high frequency voltage difference between the active and return electrodes to generate energy of at least 3.5 eV within or around the vaporized fluid.

15. The method of claim 11 further comprising applying a sufficient high frequency voltage difference between the active and return electrodes to generate energy of at least 4.0 eV within or around the vaporized fluid.

16. The method of claim 11 further comprising applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to vaporize a portion of the electrically conductive fluid such that the vaporized fluid has a temperature below about 80°

C.

17. A method for applying electrical energy to tissue comprising:

positioning an active electrode adjacent to or in contact with tissue in the presence of an electrically conductive fluid comprising at least about 1.0% sodium chloride;

applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to vaporize a portion of the electrically conductive fluid; and

effecting ablation of at least a portion of the tissue in contact with the vaporized fluid.

18. The method of claim 17 wherein the electrically conductive fluid comprises at least about 2% sodium chloride.

19. The method of claim 17 wherein the electrically conductive fluid comprises at least about 5% sodium chloride.

20. A method for applying electrical energy to tissue comprising:

positioning an active electrode adjacent to or in contact with tissue in the presence of an electrically conductive fluid comprising between about 0.1% to 0.85% sodium chloride;

applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to vaporize a portion of the electrically conductive fluid; and

effecting ablation of at least a portion of the tissue in contact with the vaporized fluid.

21. A method for applying electrical energy to tissue comprising:

positioning an active electrode near tissue in the presence of electrically conductive fluid;

applying a sufficient high frequency voltage difference between the electrode terminal and a return electrode to generate a plasma adjacent to the active electrode; and

effecting ablation of at least a portion of the tissue, while maintaining the active electrode at least 1.0 mm away from the tissue.

22. The method of claim 21 further comprising effecting ablation of at least a portion of the tissue, while maintaining the active electrode at least 2.0 mm away from the tissue.