Device and method for ablation of cardiac tissue

• US 20040015219A1
• Filed: 02/03/2003
• Published: 01/22/2004
• Est. Priority Date: 05/16/2002
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Francischelli, David E.
• Granted Patent: US 7,294,143 B2
• Time in Patent Office: Days
• US Class Current: 607/104
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 2018/00809 measured thermochromatically
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes

Abstract

Methods for delivering precise amounts of fluid into cardiac tissue for the purpose of facilitating ablation of the tissue along a desired lesion line. One method injects fluid through a hollow needle. The injected fluid can be a highly conductive fluid injected in conjunction with radiofrequency ablation to create an ablative virtual electrode. The injected conductive fluid can provide deeper and narrower conduction paths and resulting lesions. Radiofrequency ablation can be performed at the same time as the fluid injection, using the injection device as an electrode, or subsequent to the fluid injection, using a separate device. In some methods, the injected fluid is a protective fluid, injected to protect tissue adjacent to the desired lesion line. Fluid delivery can be endocardial, epicardial, and epicardial on a beating heart. The present methods find one use in performing maze procedures to treat atrial fibrillation.

Claims

1. A method for ablation of myocardial tissue comprising:

providing a hand-held instrument having a hollow needle;

selecting a desired line of ablation on a surface of the tissue;

applying the needle to the tissue at a portion of the desired line of ablation such that it penetrates the tissue; and

delivering a predetermined amount of fluid into the penetrated tissue to facilitate ablation of the tissue along the desired lesion line.

2. A method according to claim 1 wherein the needle reciprocates to repeatedly penetrate and deliver a fluid to the myocardial tissue along the desired line of ablation.

3. A method according to claim 1 wherein the fluid applied to the myocardial tissue is a cytotoxic agent applied in amount effective to ablate the myocardial tissue.

4. A method according to claim 3 wherein cytotoxic agent draws a lesion on the myocardium by the repeated introduction of the needle and injection of cytotoxic fluid while moving the tip of the device along the desired lesion pattern.

5. A method according to claim 2 wherein the fluid is introduced into the needle by means of a fluid reservoir.

6. A method according to claim 1 wherein delivery of the fluid is actively injected into the tissue according to the needle position in the myocardial tissue.

7. A method according to claim 1 wherein the fluid is delivered to the myocardium in a predetermined, metered amount.

8. A method according to claim 1 wherein the needle is withdrawn from the myocardial tissue and advanced to a second location along the desired line of ablation where the needle is inserted into the myocardium and another amount of fluid is dispensed into the myocardial tissue.

9. A method according to claim 1 also comprising the step of applying radiofrequency ablation through the needle.

10. A method according to claim 9 wherein the needle delivers a conductive liquid.

11. A method according to claim 10 wherein the conductive liquid is a saline solution that creates an ablative virtual electrode when delivered in combination with the application of radiofrequency ablation.

12. A method according to claim 9 wherein the needle is moved along the desired lesion line on the tissue as the needle is advanced into and retracted from the tissue.

13. A method according to claim 12 wherein the liquid and the ablative radiofrequency energy are synchronized to form a virtual electrode and ablate the tissue along the desired lesion line.

14. A method according to claim 1 also comprising completing delivery of fluid along the desired lesion line and subsequently applying to the desired lesion line radiofrequency ablation.

15. A method according to claim 14 wherein the fluid is a hypertonic saline solution.

16. A method according to claim 1 wherein the fluid is a protective fluid which increases the electrical impedance of the myocardial tissue.

17. A method according to claim 16 wherein the protective fluid is delivered to tissue near a heart valve.

18. A method according to claim 16 wherein the protective fluid is delivered to tissue near a blood vessel.

19. A method according to claim 16 wherein the fluid is a hypotonic fluid.

20. A method according to claim 1 wherein the fluid comprises an ink or dye.

21. A method according to claim 20 wherein the fluid comprises a cytotoxic fluid.

22. A method according to claim 20 wherein the fluid comprises a conductive fluid.

23. A method according to claim 20 wherein the fluid comprises a protective fluid.

24. A method according to claim 20 also comprising visually inspecting the ink or dye on the lesion line.

25. A method according to claim 20 wherein the ink or dye changes color at a predetermined temperature.

26. A method according to claim 1, wherein the fluid comprises a viscosity enhancing agent.

27. A method according to claim 1, wherein the delivering is performed epicardially.

28. A method according to claim 1, wherein the delivering is performed endocardially.

29. A method according to claim 1, wherein the provided hand-held instrument further comprises a needle array comprising a plurality of hollow needles in addition to the hollow needle, where in the applying includes applying the plurality of needles to penetrate the tissue, wherein the delivering includes delivering fluid into the penetrated tissue through the plurality of needles.

30. A method for ablation of myocardial tissue comprising:

providing a hand-held instrument having an injection port for injecting fluid into myocardial tissue;

selecting a desired line of ablation on a surface of the tissue;

applying the injection port to the tissue at a portion of the desired line of ablation;

delivering a predetermined amount of fluid into the myocardial tissue to facilitate ablation of the tissue along the desired lesion line.

31. A method according to claim 30 wherein the fluid applied to the myocardial tissue includes a cytotoxic agent applied in amount effective to ablate the myocardial tissue.

32. A method according to claim 30 wherein the fluid is delivered to the myocardium in a predetermined, metered amount.

33. A method according to claim 30 wherein the injection device is advanced to a second location along the desired line of ablation and another amount of fluid is dispensed into the myocardial tissue.

34. A method according to claim 30 also comprising the step of applying radiofrequency ablation through the injection device.

35. A method according to claim 34 wherein the injection device delivers a conductive liquid.

36. A method according to claim 35 wherein the conductive liquid is a saline solution that creates an ablative virtual electrode when delivered in combination with the application of radiofrequency ablation.

37. A method according to claim 34 wherein the injection port is moved along the desired lesion line on the tissue as the fluid is injected into the tissue.

38. A method according to claim 37 wherein the liquid and the ablative radiofrequency energy are synchronized to form a virtual electrode and ablate the tissue along the desired lesion line.

39. A method according to claim 30 also comprising completing delivery of fluid along the desired lesion line and subsequently applying to the desired lesion line radiofrequency ablation.

40. A method according to claim 39 wherein the fluid is a hypertonic saline solution.

41. A method according to claim 30 wherein the fluid is a protective fluid which increases the electrical impedance of the myocardial tissue.

42. A method according to claim 41 wherein the protective fluid is delivered to tissue near a heart valve.

43. A method according to claim 41 wherein the protective fluid is delivered to tissue near a blood vessel.

44. A method according to claim 41 wherein the fluid is a hypotonic fluid.

45. A method according to claim 30 wherein the fluid comprises an ink or dye.

46. A method according to claim 45 wherein the fluid comprises a cytotoxic fluid.

47. A method according to claim 45 wherein the fluid comprises a conductive fluid.

48. A method according to claim 45 wherein the fluid comprises a protective fluid.

49. A method according to claim 45 also comprising visually inspecting the ink or dye on the lesion line.

50. A method according to claim 30 wherein the ink or dye changes color at a predetermined temperature.

51. A method according to claim 30, wherein the fluid comprises a viscosity enhancing agent.

52. A method according to claim 30, wherein the delivering is performed epicardially.

53. A method according to claim 30, wherein the delivering is performed epicardially on a beating heart.

54. A method according to claim 30, wherein the delivering is performed endocardially.