Methods for tissue ablation using pulsed energy

• US 7,445,618 B2
• Filed: 01/24/2007
• Issued: 11/04/2008
• 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:
  US11/626,656
• Publication Number:
  US 20070112348A1
• Time in Patent Office: 650 Days
• Field of Search: 606/32, 606/41
• US Class Current: 606/32
• 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 comprises a shaft having an electrode array (12) at its distal end and a connector at its proximal end. The array (12) includes a plurality of isolated electrode terminals, and an electrosurgical power supply (28) 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 impedance paths, such as blood and normal saline, will be minimized.

Claims

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

providing an electrode terminal and a return electrode electrically coupled to a high frequency voltage source;

positioning the electrode terminal in close proximity to the target site in the presence of an electrically conductive fluid, said electrically conductive fluid from a fluid source located outside of the patient;

applying a high frequency voltage between the electrode terminal and the return electrode, the high frequency voltage being sufficient to vaporize the fluid in a thin layer over at least a portion of the electrode terminal; and

inducing the discharge of energy to the target site in contact with the vapor layer after said step of applying a high frequency voltage

wherein said applying step is carried out by applying pulses of energy.

2. The method of claim 1 wherein said return electrode is positioned away from said target site such that there is no contact between said target site and said return electrode.

3. A method for applying energy to a soft tissue at a target site of a patient comprising:

providing a probe having a distal end section, said distal end section comprising at least one electrode terminal and a common electrode electrically coupled to a high frequency voltage supply;

positioning the electrode terminal in close proximity to the target site in the presence of an electrically conductive fluid, said electrically conductive fluid from a fluid source from outside the patient;

applying a high frequency voltage between the electrode terminal and the common electrode such that a current path is present through the electrically conductive fluid, and such that tissue is ablated in the vicinity of the electrode terminal; and

wherein said distal section is adapted to minimize direct contact between the common electrode and the target site and

wherein said applying step is carried out by applying pulses of energy to said soft tissue.

4. The method of claim 3 wherein said electrically conductive fluid is isotonic saline.

5. The method of claim 4 wherein said common electrode is partially covered with an insulative shield.

6. The method of claim 3 wherein said probe comprises only one electrode terminal.

7. The method of claim 3 wherein said applying step causes tissue to be removed.

8. The method of claim 3 wherein said probe comprises a shaft, and wherein said shaft is an elongate rigid member and said electrode terminal is a protrusion at the distal end section of said shaft, and wherein said common electrode is axially spaced proximal of the electrode terminal.

9. The method of claim 3 wherein said common electrode is substantially larger than said electrode terminal.

10. The method of claim 3 wherein said tissue is located within the shoulder.

11. The method of claim 3 wherein said method is carried out arthroscopically.

12. The method of claim 3 wherein said frequency is in the range from 20 KHz to about 20 MHz.

13. The method of claim 3 wherein said pulses comprise a first pulse and a second pulse and said pulses have a duration, magnitude, and time interval therebetween, to achieve ablation while allowing the temperature of the tissue to return to a normal physiologic temperature prior to the second pulse.

14. The method of claim 3 wherein said frequency is in the range from about 30 KHz to 1 MHz.

15. The method of claim 3 wherein said frequency is in the range from about 50 KHz to 400 KHz.

16. The method of claim 3 wherein said common electrode is spaced proximally from said electrode terminal on a shaft of the probe device.

17. A method for applying energy to soft tissue at a target site of a patient comprising:

providing an electrode terminal and a return electrode electrically coupled to a high frequency voltage source;

positioning the electrode terminal in close proximity to the target site in the presence of an electrically conductive fluid, said electrically conductive fluid from a fluid source located outside of the patient;

applying a high frequency voltage between the electrode terminal and the return electrode from a voltage source, the high frequency voltage being sufficient to vaporize the fluid in a thin layer over at least a portion of the electrode terminal; and

inducing the discharge of energy to the target site in contact with the vapor layer after said step of applying a high frequency voltage and

wherein said applying step is carried out by turning on and off said voltage source.

18. The method of claim 17 wherein said electrically conductive fluid is isotonic saline.

19. The method of claim 17 wherein said return electrode is partially covered with an insulative shield.

20. The method of claim 17 wherein said soft tissue is selected from the group consisting of cartilage, ligament, tendon, and meniscus.

21. The method of claim 17 wherein said return electrode is substantially larger than said electrode terminal.

22. The method of claim 17 wherein said frequency is in the range from 20 KHz to about 20 MHz.

23. The method of claim 17 wherein said frequency is in the range from about 30 KHz to 1 MHz.

24. The method of claim 17 wherein said frequency is in the range from about 50 KHz to 400 KHz.

25. The method of claim 17 wherein said return electrode is spaced proximally from said electrode terminal on a shaft of a probe device.