Method for creating a virtual electrode for the ablation of tissue and for selected protection of tissue during an ablation

• US 6,494,902 B2
• Filed: 07/06/1999
• Issued: 12/17/2002
• Est. Priority Date: 07/07/1998
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Hoey, Michael F., Mulier, Peter M. J.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US09/347,363
• Publication Number:
  US 20020058935A1
• Time in Patent Office: 1,260 Days
• Field of Search: 606/41, 606/45-50, 607/101-105, 604/22, 128/898
• US Class Current: 607/105
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2218/002 Irrigation

Abstract

The present invention provides an apparatus and a method for producing a virtual electrode within or upon a tissue to be treated with radiofrequency alternating electric current, such tissue including but not limited to liver, lung, cardiac, prostate, breast, and vascular tissue and neoplasms. An apparatus in accordance with the present invention includes a radiofrequency alternating electric current source and a radiofrequency ablating a fluid source. A surgical instrument is connected to both the current source and the fluid source for delivering a fluid and a current to a first portion of tissue to be ablated. The apparatus also includes a protective fluid source and a delivery system connected to the protective fluid source for delivery of protective fluid to a secondary portion of tissue whose ablation is not desired.

A method in accordance with the present invention will include the steps of providing a radiofrequency ablating fluid to a first portion of tissue to be ablated, providing a radiofrequency alternating electric current to the first portion of tissue to be ablated, and providing a protective fluid to a second portion of tissue whose ablation is not desired.

Claims

1. A method for the ablation of tissue and for the selected protection of tissue during an ablation therapy, the method comprising:

delivering a conductive fluid to a target tissue site;

penetrating a surface of a neighboring tissue site, wherein the neighboring tissue site is adjacent the target tissue site and ablation of the neighboring tissue site is not desired;

infusing a protective fluid into tissue of the neighboring tissue site through the surface; and

applying an electrical current to the delivered conductive fluid to ablate tissue of the target tissue site;

wherein the protective fluid reduces ablation of the neighboring tissue site.

2. The method of claim 1, wherein delivering a conductive fluid includes:

infusing the conductive fluid into the target tissue site.

3. The method of claim 1, wherein delivering a conductive fluid includes:

providing the conductive fluid to the surface of the target tissue site.

4. The method of claim 1, wherein applying an electrical current to the delivered conductive fluid renders the delivered conductive fluid capable of ablating tissue.

5. The method of claim 1, further comprising:

positioning an electrode to apply the electrical current to the conductive fluid.

6. The method of claim 5, wherein positioning the electrode includes contacting the delivered conductive fluid.

7. The method of claim 5, wherein positioning the electrode includes laterally spacing the electrode from the infused protective fluid.

8. The method of claim 5, wherein the electrode is positioned on a surface of the target tissue site to apply electrical current to the delivered conductive fluid.

9. The method of claim 5, wherein the electrode is positioned within the target tissue site to apply electrical current to the delivered conductive fluid.

10. The method of claim 5, wherein the neighboring tissue site has a front, a back, and a perimeter, and the electrode is laterally offset from the perimeter of the neighboring tissue site infused with the protective fluid.

11. The method of claim 5, wherein the target tissue site is defined by a front, a back, and a perimeter, and the neighboring tissue site is laterally offset from the perimeter of the target tissue site.

12. The method of claim 11, wherein the electrode is not aligned with the neighboring tissue site during the step of applying an electrical current.

13. The method of claim 12, wherein the electrode is aligned with the front of the target tissue site during the step of applying an electrical current.

14. The method of claim 1, wherein the step of infusing a protective fluid further comprises:

providing a sugar solution consisting of water and dextrose to the neighboring tissue site.

15. The method of claim 1, wherein the step of infusing a protective fluid further comprises:

providing a sugar solution consisting of water and sucrose to the neighboring tissue site.

16. The method of claim 1, wherein the step of infusing a protective fluid further comprises:

providing a biocompatible non-conductive solution to the neighboring tissue site.

17. The method of claim 1, wherein the steps of delivering a conductive fluid and applying electrical current further comprises:

providing the conductive fluid and the electrical current via a single needle.

18. The method of claim 1, wherein the steps of delivering a conductive fluid and applying electrical current further comprises:

providing the conductive fluid and the electrical current via a plurality of needles.

19. The method of claim 1, wherein the step of infusing a protective fluid further comprises:

providing a protective fluid to the neighboring tissue site via a single needle.

20. The method of claim 1, wherein the step of infusing a protective fluid further comprises:

providing a protective fluid to the neighboring tissue site via a plurality of needles.

21. The method of claim 1, wherein the step of infusing a protective fluid includes:

surrounding the target tissue site with protective fluid.

22. The method of claim 1, wherein the step of infusing a protective fluid includes:

creating a plurality of protective fluid boluses about the target tissue site.

23. The method of claim 1, wherein the step of infusing a protective fluid includes:

providing a chilled, electrically non-conductive fluid to the neighboring tissue site.

24. The method of claim 1, wherein the target tissue site is a tumor, and further wherein delivering a conductive fluid includes:

injecting the conductive fluid into the tumor.

25. The method of claim 24, wherein the neighboring tissue site is healthy tissue about the tumor.

26. The method of claim 1, wherein infusing a protective fluid includes reducing a conductivity of the neighboring tissue site.