System and method of performing an electrosurgical procedure

• US 7,364,578 B2
• Filed: 12/03/2004
• Issued: 04/29/2008
• Est. Priority Date: 01/25/2002
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Francischelli, David, Mehra, Rahul, Lutterman, Alison
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US11/003,451
• Publication Number:
  US 20050165392A1
• Time in Patent Office: 1,243 Days
• Field of Search: 606 32- 34, 606 38- 42, 607/101, 607/102
• US Class Current: 606/34
• 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 2018/00029 open
• CPC Class Codes: A61B 2018/00351 Heart
• CPC Class Codes: A61B 2018/00363 Epicardium
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00738 Depth, e.g. depth of ablation
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes

Abstract

A system and method of making a lesion on living tissue including providing an electrosurgical system, determining a desired lesion depth, selecting a power setting, and applying electrical energy to the living tissue. The system includes an instrument having an electrode at a distal portion thereof, and a power source having multiple available power settings. The power source is electrically connected to the electrode. The step of applying electrical energy includes energizing the electrode at the selected power setting for a recommended energization time period that is determined by reference to predetermined length of time information and based upon the desired lesion depth and the selected power setting. The system preferably further includes a fluid source for irrigating the electrode at an irrigation rate. In this regard, the predetermined length of time information is generated as a function of irrigation rate.

Claims

1. A method of creating an ablation lesion at a tissue target site, the method comprising:

providing an ablation system including;

an ablation instrument having a tissue ablating member, and

an ablative energy source having multiple available ablative energy settings, wherein the ablative energy source supplies ablative energy to the tissue ablating member;

determining a desired depth for the ablation lesion;

selecting a desired ablative energy setting for the ablative energy source, including considering a probability that the tissue target site will be heated so rapidly that intracellular fluid within the tissue target site will begin to boil and at least a portion of the tissue target site will erupt causing undesirable damage during a subsequent ablation procedure; and

supplying ablative energy to the tissue ablating member in contact with the tissue target site, the ablative energy supplied to the tissue ablating member at the desired ablative energy setting for a recommended energization time period determined by reference to predetermined length of time information and based upon the desired lesion depth and the selected ablative energy setting;

wherein the step of selecting a desired ablative energy setting is completed prior to determining the recommended energization time period, and the recommended energization time period is determined prior to the step of supplying ablative energy to the tissue ablating member.

2. The method of claim 1, wherein the predetermined length of time information correlates a plurality of lesion depth values with a plurality of ablative energy setting values and identifies an energization time period value for each lesion depth value and ablative energy setting value combination.

3. The method of claim 2, wherein the recommended energization time period is determined by ascertaining the energization time period value identified by the predetermined length of time information that otherwise corresponds with the desired lesion depth and the selected ablative energy setting combination.

4. The method of claim 3, wherein the predetermined length of time information is embodied in a look-up table.

5. The method of claim 3, wherein the predetermined length of time information includes an algorithm.

6. The method of claim 3, wherein the ablation instrument is further configured to distribute a liquid from a fluid source to a region of the tissue ablating member at a plurality of irrigation rates, and further wherein the predetermined length of time information is generated as a function of irrigation rate.

7. The method of claim 6, further comprising selecting a desired irrigation rate prior to the step of supplying ablative energy and irrigating the tissue ablating member with the liquid during the step of supplying ablative energy.

8. The method of claim 7, wherein the recommended energization time period is further determined based upon the selected irrigation rate.

9. The method of claim 8, wherein the predetermined length of time information includes a first correlation of lesion depth values with ablative energy setting values for a first irrigation rate and a second correlation of lesion depth values with ablative energy setting values for a second irrigation rate.

10. The method of claim 9, wherein the predetermined length of time information includes a first look-up table embodying the first correlation and a second look-up table embodying the second correlation.

11. The method of claim 1, wherein determining a desired lesion depth includes:

estimating a thickness of the tissue target site.

12. The method of claim 1, wherein the ablative energy supplied to the tissue ablating member is radiofrequency energy.

13. The method of claim 1, wherein selecting a desired ablative energy setting further includes:

considering a probable period of time for making the lesion.

14. The method of claim 13, wherein selecting a desired ablative energy setting further includes:

balancing a first risk associated with the probability that the tissue target site will be heated so rapidly that intracellular fluid within the tissue target site will begin to boil and at least a portion of the tissue target site will erupt causing undesirable damage and a second risk associated with the probable period of time.

15. The method of claim 1, wherein the predetermined length of time information corresponds to a length of time needed for the ablation system to create a lesion having a length of 1 cm.

16. The method of claim 1, further comprising:

drawing the tissue ablating member back and forth across the tissue target site during the step of supplying ablative energy to the tissue ablating member.

17. The method of claim 16, wherein the step of drawing the tissue ablating member back and forth results in a first lesion segment upon completion of the recommended energization time period, the method further comprising forming a second lesion segment connected to the first lesion segment to define a lesion pattern.

18. The method of claim 17, wherein the lesion pattern is created as a part of a Maze procedure.

19. The method of claim 1, wherein the ablation system further includes a controller storing the predetermined length of time information, and further wherein the recommended energization time period is determined by:

operating the controller to reference the predetermined length of time information.

20. The method of claim 19, wherein the controller includes an input device and a display device, and further wherein operating the controller includes:

inputting the desired lesion depth and the selected ablative energy setting via the input device;

automatically applying the desired lesion depth and the selected ablative energy setting to the predetermined length of time information to determine the recommended energization time period; and

displaying the recommended energization time period via the display device.

21. The method of claim 19, wherein the controller further includes a warning device, the method further comprising:

activating the warning device upon completion of the recommended energization time period.

22. The method of claim 1, wherein the tissue ablating member is an ablation electrode.

23. The method of claim 1, wherein the tissue ablating member is positioned at a distal portion of the ablation instrument.

24. The method of claim 1, wherein at least a portion of the tissue ablating member is porous.

25. The method of claim 1, wherein the ablative energy source is a radiofrequency generator.

26. The method of claim 1, wherein the tissue target site is heart tissue.

27. The method of claim 26, wherein the heart tissue is epicardial tissue.

28. The method of claim 26, wherein the heart tissue is endocardial tissue.

29. The method of claim 1, further comprising the step of gaining access to the tissue target site through a sternotomy.

30. The method of claim 1, further comprising the step of gaining access to the tissue target site through a thoractomy.

31. The method of claim 1, further comprising the step of gaining access to the tissue target site through a small incision.

32. The method of claim 1, further comprising the step of gaining access to the tissue target site through a port.

33. The method of claim 1, further comprising the step of gaining access to the tissue target site percutaneously.

34. The method of claim 1, further comprising the step of gaining access to the tissue target site transveneously.

35. An ablation system for creating an ablation lesion at a tissue target site, the system comprising:

an ablation instrument having a tissue ablating member;

an ablative energy source having multiple available ablative energy settings and being connected to the ablation instrument for selectively supplying ablative energy to the tissue ablating member; and

an energization look-up table corresponding with the ablation instrument, the energization look-up table including;

an ablative energy setting data set that includes at least one of the multiple available ablative energy settings of the ablative energy source,

a lesion depth data set,

energization time period information organized as a dependent variable of the ablative energy setting and lesion depth data sets;

wherein the energization look-up table is adapted to identify a recommended energization time period based upon a desired lesion depth by a cross-reference between energization time and ablative energy setting for minimizing a possibility that the tissue target site will be heated so rapidly that intracellular fluid within the tissue target site will begin to boil and at least a portion of the tissue target site will erupt causing undesirable damage during the creation of the ablation lesion.

36. The system of claim 35, further including:

a fluid source fluidly connected to the ablation instrument, the fluid source being configured to supply a liquid to a region of the tissue ablating member at an irrigation rate during the creation of the ablation lesion.

37. The system of claim 36, wherein the energization look-up table correlates the energization time period information with a desired irrigation rate.

38. The system of claim 35, wherein the system further comprises:

a controller electronically storing the energization look-up table, wherein the controller is adapted to convert the selected ablative energy setting and the desired lesion depth into a recommended energization time period based upon reference to the energization look-up table.

39. The system of claim 38, wherein the controller is electrically connected to the ablative energy source, and further wherein the controller is configured to control the ablative energy setting of the ablative energy source.

40. The system of claim 39, wherein the controller is adapted to automatically deactivate the ablative energy source upon completion of the recommended energization time period.

41. The system of claim 38, wherein the controller includes an input device and a display device, and further wherein operating the controller includes:

inputting the desired lesion depth and the selected ablative energy setting via the input device;

automatically applying the desired lesion depth and the selected ablative energy setting to the predetermined length of time information to determine the recommended energization time period; and

displaying the recommended energization time period via the display device.

42. The system of claim 41, wherein the controller further includes a warning device that is activated upon completion of the recommended energization time period.

43. The system of claim 35, wherein the tissue ablating member is an ablation electrode.

44. The system of claim 35, wherein the tissue ablating member is positioned at a distal portion of the ablation instrument.

45. The system of claim 35, wherein at least a portion of the tissue ablating member is porous.

46. The system of claim 35, wherein the ablative energy source is a radiofrequency generator.

47. The system of claim 46, wherein the ablative energy supplied to the tissue ablating member is radiofrequency energy.

48. The system of claim 35, wherein the ablation instrument is further configured to distribute a liquid from a fluid source to a region of the tissue ablating member at a plurality of irrigation rates.