Apparatus and method for ablating tissue

• US 6,645,202 B1
• Filed: 10/27/2000
• Issued: 11/11/2003
• Est. Priority Date: 10/22/1996
• Status: Expired due to Fees

• Current Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Original Assignee: Epicor Medical, Inc. (Abbott Laboratories Incorporated)
• Inventors: Vaska, Matthias, Richman, Roxanne L., Anderson, Scott C., Gallup, David A., Podmore, Jonathan L., Pless, Benjamin, Ciciarelli, Timothy, Ulstad, Jack E. Jr., Crowe, John E.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US09/699,215
• Time in Patent Office: 1,110 Days
• Field of Search: 606/27, 606/28, 606/41, 606/169, 604/22, 600/437, 600/439, 600/459, 600/462, 600/466, 600/472, 601/2, 601/3
• US Class Current: 606/41
• CPC Class Codes: A61B 17/22012 in direct contact with, or very close to, the obstruction or concrement for removing obstructions in blood vessels by laser A61B18/245
• CPC Class Codes: A61B 17/2202 the ultrasound transducer being inside patient's body at the distal end of the catheter
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 18/02 by cooling, e.g. cryogenic techniques devices for cooling specific reflex points of the body within cell-life limits A61H39/06
• 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 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 2017/00243 cardiac
• CPC Class Codes: A61B 2017/00247 Making holes in the wall of the heart, e.g. laser Myocardial revascularization
• CPC Class Codes: A61B 2017/00252 for by-pass connections, i.e. connections from heart chamber to blood vessel or from blood vessel to blood vessel
• CPC Class Codes: A61B 2017/003 Steerable
• CPC Class Codes: A61B 2017/22077 with a part piercing the tissue A61B2017/22044 takes precedence
• CPC Class Codes: A61B 2017/3419 Sealing means between cannula and body
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00232 having an irregular shape
• CPC Class Codes: A61B 2018/00261 arranged in a line
• CPC Class Codes: A61B 2018/00285 Balloons
• CPC Class Codes: A61B 2018/00291 : using suction
• CPC Class Codes: A61B 2018/00351 : Heart
• CPC Class Codes: A61B 2018/00363 : Epicardium
• CPC Class Codes: A61B 2018/00392 : Transmyocardial revascularisation
• CPC Class Codes: A61B 2018/00577 : Ablation
• CPC Class Codes: A61B 2018/00654 : with individual control of each of a plurality of energy emitting elements
• CPC Class Codes: A61B 2018/00797 : measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00839 : Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2018/142 : at least partly surrounding the target, e.g. concave, curved or in the form of a cave
• 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 2090/3614 : using optical fibre
• CPC Class Codes: A61B 2090/3782 : transmitter or receiver in catheter or minimal invasive instrument
• CPC Class Codes: A61B 2090/395 : with marking agent for marking skin or other tissue
• CPC Class Codes: A61B 2218/002 : Irrigation
• CPC Class Codes: A61B 2218/007 : Aspiration
• CPC Class Codes: A61B 34/20 : Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 5/287 : Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61N 1/06 : for high-frequency therapy
• CPC Class Codes: A61N 1/3629 : in combination with non-electric therapy
• CPC Class Codes: A61N 2007/0065 : Concave transducers
• CPC Class Codes: A61N 2007/0078 : with multiple treatment transducers
• CPC Class Codes: A61N 2007/027 : with multiple foci created simultaneously
• CPC Class Codes: A61N 7/02 : Localised ultrasound hyperthermia hyperthermia in general A61F7/00

Abstract

A control system alters one or more characteristics of an ablating element to ablate tissue. In one aspect, the control system delivers energy nearer to the surface of the tissue by changing the frequency or power. In another aspect, the ablating element delivers focused ultrasound which is focused in at least one dimension. The ablating device may also have a number of ablating elements with different characteristics such as focal length.

Claims

1. A method of ablating cardiac tissue, comprising the steps of:

providing an ablating device having an ultrasonic transducer, the device emitting focused ultrasound which is focused in at least one dimension;

positioning the ablating device in contact with cardiac tissue; and

activating the ultrasonic transducer to direct the focused ultrasound into the cardiac tissue, the activating step is carried out by activating the ultrasonic transducer for a first period of time at a first frequency and a second period of time at a second frequency which is different than the first frequency and occurs after the first period of time.

2. The method of claim 1, wherein:

the activating step is carried out to electrically isolate one part of the heart from another part of the heart.

3. The method of claim 1, wherein:

the providing and activating steps are carried out with the focused ultrasound being focused along a focal axis and diverging when viewed perpendicular to the focal axis.

4. The method of claim 1, further comprising the step of:

moving a focus of the focused ultrasound relative to the cardiac tissue.

5. The method of claim 4, wherein:

the moving step is carried out to move the focus closer to a near surface of the cardiac tissue.

6. The method of claim 1, wherein:

the providing step is carried out so that at least 90% of the focused ultrasound passes within a focus area defined by a focal length of about 2 to 20 mm and an angle of about 10 to 170 degrees when viewed along a focal axis.

7. The method of claim 1, wherein:

the providing step is carried out with the focused energy being emitted by a concave surface.

8. The method of claim 7, wherein:

the providing step is carried out with the concave surface having a focal length of 2-20 mm.

9. The method of claim 8, wherein:

the providing step is carried out with the focused energy having a focal length of 2 to 12 mm.

10. The method of claim 1, wherein:

the activating step is carried out with the first frequency being lower than the second frequency.

11. The method of claim 1, wherein:

the activating step is carried out with the first period of time being shorter than the second period of time.

12. The method of claim 11, wherein:

the activating step is carried out with the first period of time being less than 1 second.

13. The method of claim 1, wherein:

the activating step is carried out with the ultrasonic transducer being activated at the first frequency for a number of discrete time periods.

14. The method of claim 1, wherein:

the activating step is carried out by changing the frequency to accumulate energy closer to a near surface of the tissue.

15. The method of claim 14, wherein:

the activating step is carried out with the frequency being increased from a first frequency to a second frequency, the activating step being carried out at the first frequency for a number of discrete periods of time.

16. The method of claim 1, wherein:

the providing step is carried out with the ultrasonic transducer producing the focused ultrasound having a focal length of 2-20 mm.

17. The method of claim 1, further comprising the step of:

assessing contact between the ablating device and the tissue structure.

18. The method of claim 1, wherein:

assessing contact between the ablating device and the tissue structure by measuring the electrical impedance.

19. The method of claim 1, further comprising the step of:

measuring a tissue thickness using ultrasound energy delivered by the ablating device.

20. The method of claim 1, further comprising the step of:

measuring a fat thickness using ultrasound energy delivered by the abating device.

21. The method of claim 1, wherein:

the activating step is carried out with the ablating element being activated at the first frequency for a number of discrete time periods.

22. The method of claim 1, wherein:

the activating step is carried out by activating the ultrasonic transducer at a third frequency different than the first and second.

23. The method of claim 1, wherein:

the activating step is carried out with the first frequency being about 2-7 MHz and the second frequency being from 2-14 MHz.

24. The method of claim 1, further comprising the step of:

measuring a blood flow velocity with the ultrasonic transducer.

25. The method of claim 1, further comprising the step of:

determining a tissue layer thickness using the ultrasound transducer.

26. The method of claim 1, wherein:

the determining step is carried out with the tissue layer being a tissue layer between a near surface and a far surface.

27. The method of claim 1, further comprising the step of:

moving an ultrasonic beam emitted by the ultrasound transducer after the activating step.

28. The method of claim 27, further comprising the step of:

tilting the ultrasonic beam.

29. A method of ablating cardiac tissue with ultrasound comprising the steps of:

creating an opening in a patient'"'"'s chest;

providing an ablating device which emits focused ultrasound having a focus in at least one direction;

introducing the ablating device through the opening in the patient'"'"'s chest;

positioning the ablating device in contact with a cardiac tissue structure to be ablated, the cardiac tissue structure having a near wall and a far wall; and

operating the ablating device at a frequency and a power to direct the ultrasonic energy into the tissue structure for a number of discrete time periods; and

changing at least one of the frequency and location of the focus relative to the tissue and activating the ablating device to ablate the cardiac tissue structure for another period of time.

30. The method of claim 29, wherein:

the changing step is carried out with the frequency increasing.

31. The method of claim 29, wherein:

the providing step is carried out with the ablating device producing focused ultrasound, wherein the focused ultrasound has a focal length of 2-20 mm.

32. The method of claim 29, further comprising the step of:

assessing contact between the ablating device and the tissue structure.

33. The method of claim 29, further comprising the step of:

assessing contact between the ablating device and the tissue structure by measuring the electrical impedance.

34. The method of claim 29, further comprising:

measuring a tissue thickness using ultrasound energy delivered by the ablating device.

35. The method of claim 29, further comprising the step of:

measuring a fat thickness using ultrasound energy delivered by the ablating device.

36. The method of claim 29, wherein:

the activating step is carried out with the ablating device being activated at a first frequency for a number of discrete time periods.

37. The method of claim 29, wherein:

the changing step is carried out by activating the ablating device at a frequency of 2-14 MHz.

38. The method of claim 29, wherein:

the activating step is carried out at a first frequency of 2-7 MHz; and

the changing step is carried out at a second frequency of 2-14 MHz.

39. The method of claim 29, further comprising the step of:

measuring a blood flow velocity with ultrasound energy delivered by the ablating device.

40. The method of claim 29, further comprising the step of:

determining a tissue layer thickness using ultrasound energy delivered by the ablating device.

41. The method of claim 29, further comprising the step of:

moving an ultrasonic beam emitted by the ablating device after the activating step.

42. The method of claim 29, further comprising the step of:

tilting an ultrasonic beam emitted by the ablating device after the activating step.

43. A method of ablating cardiac tissue to form an elongate lesion to treat a cardiac arrhythmia, comprising the steps of:

providing an ablating device having a plurality of ablating elements, the plurality of ablating elements each emitting focused ultrasound, the focused ultrasound being focused in at least one direction and having a focal length of 2-20 mm;

forming an opening in a patient'"'"'s chest;

introducing the ablating device through the opening in the patient'"'"'s chest;

positioning the ablating device against an epicardial surface overlying a cardiac tissue structure to be ablated, the cardiac structure having a near wall and a far wall; and

activating the plurality of ablating elements each for a number of discrete periods of time, the ablating element emitting focused ultrasound into the cardiac tissue structure to ablate the cardiac tissue structure to treat the cardiac arrhythmia.

44. The method of claim 43, wherein:

the positioning step is carried out with the plurality of ablating elements extending around the pulmonary veins on the epicardial surface.

45. The method of claim 43, wherein:

the positioning step is carried out with the plurality of ablating elements being angled relative to the epicardial surface to at least partially direct the focused ultrasound toward an adjacent ablating element.

46. The method of claim 43, wherein:

changing a characteristic of the ablating device and activating the ablating device to produce focused ultrasound which accumulates energy closer to the near wall as compared to the activating step.

47. The method of claim 46, wherein:

the changing step is carried out with the frequency increasing.

48. The method of claim 43, further comprising the step of:

assessing contact between the ablating device and the tissue structure.

49. The method of claim 43, wherein:

assessing contact between the ablating device and the tissue structure by measuring the electrical impedance.

50. The method of claim 43, further comprising:

measuring a tissue thickness using ultrasound energy delivered by the ablating device.

51. The method of claim 43, further comprising the step of:

measuring a fat thickness using ultrasound energy delivered by the ablating device.

52. The method of claim 43, wherein:

the activating step is carried out with at least one of the ablating elements being activated at a first frequency for a number of discrete time periods.

53. The method of claim 52, wherein:

the activating step is carried out with the at least one ablating element being activated at a second frequency different than the first frequency.

54. The method of claim 53, wherein:

the activating step is carried out with the first frequency being about 2-7 MHz and the second frequency being from 2-14 MHz.

55. The method of claim 43, further comprising the step of:

moving an ultrasonic beam emitted by the ablating device after the activating step.

56. The method of claim 43, further comprising the step of:

tilting an ultrasonic beam emitted by the ablating device after the activating step.