Externally-applied high intensity focused ultrasound (HIFU) for pulmonary vein isolation

• US 20040162550A1
• Filed: 02/19/2003
• Published: 08/19/2004
• Est. Priority Date: 02/19/2003
• Status: Active Grant

• Current Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Original Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Inventors: Govari, Assaf, Schwartz, Yitzhack
• Granted Patent: US 7,201,749 B2
• Time in Patent Office: Days
• US Class Current: 606/27
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

Apparatus is provided for performing ablation of cardiac tissue using ultrasound. The apparatus includes a beacon, adapted to be placed at a cardiac site in a body of a subject. The apparatus further includes a set of ultrasound transducers, each transducer adapted to detect a respective ultrasound signal coming from the beacon. Each transducer is adapted to output a time-reversed ultrasound signal, reversed in time with respect to a property of at least one of the beacon signals, and configured to ablate the cardiac tissue.

Claims

1. Apparatus for performing ablation of cardiac tissue using ultrasound, comprising:

a beacon, adapted to be placed at a cardiac site in a body of a subject; and

a set of ultrasound transducers, each transducer adapted to detect a respective ultrasound signal coming from the beacon, and adapted to output a time-reversed ultrasound signal, reversed in time with respect to a property of at least one of the beacon signals, and configured to ablate the cardiac tissue.

2. Apparatus according to claim 1, wherein the set of transducers is adapted to be applied to an external surface of the body of the subject.

3. Apparatus according to claim 1, wherein each transducer is adapted to configure its time-reversed signal to be reversed in time and shape with respect to a property of the beacon signal detected by that transducer.

4. Apparatus according to claim 1, wherein each transducer is adapted to amplify the time-reversed signal prior to outputting the time-reversed signal.

5. Apparatus according to claim 1, wherein the beacon is adapted to be placed at the cardiac site using a cardiac map of at least a portion of a heart of the subject.

6. Apparatus according to claim 1, wherein the one or more transducers comprise a single ultrasound transducer, and wherein the single ultrasound transducer is adapted to output the time-reversed signal reversed in time with respect to a shape of the beacon signal detected by the single ultrasound transducer.

7. Apparatus according to claim 1, wherein the one or more transducers comprise a plurality of transducers, each adapted to output the time-reversed signal reversed in time with respect to a sequence of detecting the beacon signal at the plurality of transducers.

8. Apparatus according to claim 1, wherein each transducer is adapted to regulate a timing parameter of the outputting of the respective time-reversed signal, responsive to a position of the transducer, a position of the beacon, and a position of the cardiac tissue.

9. Apparatus according to claim 1, comprising a catheter having a distal end, which is adapted to be inserted into the body and brought to the cardiac site, wherein the beacon is adapted to be affixed in a vicinity of the distal end of the catheter.

10. Apparatus according to claim 1, wherein the transducers are adapted to configure the respective time-reversed ultrasound signals to form one or more non-conducting lesions in the cardiac tissue.

11. Apparatus according to claim 10, wherein the cardiac tissue includes tissue that generates undesired electrical signals, and wherein the transducers are adapted to configure the respective time-reversed ultrasound signals to be such as to form the one or more non-conducting lesions in the cardiac tissue.

12. Apparatus according to claim 10, wherein the cardiac tissue includes tissue through which propagate undesired electrical signals initially generated at a site outside of the cardiac tissue, and wherein the transducers are adapted to configure the respective time-reversed ultrasound signals to be such as to form the one or more non-conducting lesions in the cardiac tissue.

13. Apparatus according to claim 1, wherein the beacon is adapted to be placed in a vicinity of a pulmonary vein of the subject.

14. Apparatus according to claim 13, wherein the beacon is adapted to be placed in a vicinity of an ostium of the pulmonary vein.

15. Apparatus according to claim 1,

wherein the beacon comprises a passive element,

wherein the apparatus comprises an ultrasound transmitter, adapted to illuminate the beacon with an illuminating ultrasound signal, and

wherein each transducer is adapted to detect an echo signal coming from the beacon responsive to illumination by the illuminating signal, and to output the time-reversed signal, reversed in time with respect to a property of the echo signal detected by that transducer.

16. Apparatus according to claim 15, wherein the transmitter comprises one of the transducers.

17. Apparatus according to claim 15, wherein the passive element comprises an ultrasound reflector, characterized by higher ultrasound reflectivity than a natural level of ultrasound reflectivity at the cardiac site.

18. Apparatus according to claim 15, wherein the passive element is of a geometry that produces a distinguishable signature in the echo signal when the element is illuminated by the transmitter, and wherein one or more of the transducers are adapted to detect the signature in the echo signal and to output the time-reversed signal responsive thereto.

19. Apparatus according to claim 15, wherein the passive element comprises a crystal having a predefined resonance frequency.

20. Apparatus according to claim 15, wherein the passive element comprises an ultrasound contrast agent that reflects a known harmonic of the illuminating signal, and wherein one or more of the transducers are adapted to detect the known harmonic and to output the time-reversed signal responsive thereto.

21. Apparatus according to claim 1, comprising a control unit, adapted to store the beacon signals received from the beacon by each transducer, and adapted to drive each transducer to output its respective time-reversed signal.

22. Apparatus according to claim 21, wherein each transducer is adapted to transform the beacon signals it receives into electrical signals, and to transmit the electrical signals to the control unit.

23. Apparatus according to claim 21, wherein the control unit is adapted to drive each transducer to configure its respective time-reversed signal to have a greater amplitude than a corresponding amplitude of the beacon signal received by the respective transducer.

24. Apparatus according to claim 1, wherein the beacon comprises circuitry to receive energy, and wherein the beacon is adapted to transduce the received energy so as to generate the beacon signal.

25. Apparatus according to claim 24, wherein the beacon is adapted to configure the beacon signal to include one or more generally omnidirectional pulses.

26. Apparatus according to claim 24, comprising:

external power circuitry; and

a set of one or more wires connecting the external power circuitry to the beacon,

wherein the external power circuitry is adapted to transmit the energy to the beacon through the wires.

27. Apparatus according to claim 24, wherein the circuitry is adapted to receive the energy wirelessly.

28. Apparatus according to claim 27, comprising a power transmitter, adapted to be located outside the body, and to wirelessly transmit the energy to the beacon.

29. Apparatus according to claim 28, wherein the power transmitter is adapted to wirelessly transmit ultrasound energy to the beacon.

30. Apparatus according to claim 28, wherein the power transmitter is adapted to wirelessly transmit electromagnetic energy to the beacon.

31. Apparatus according to claim 1, wherein the beacon is adapted to be placed in sequence at a plurality of locations in a vicinity of the cardiac site.

32. Apparatus according to claim 31, wherein the beacon is adapted to be placed at the plurality of locations, such locations including at least four non-coplanar locations.

33. Apparatus according to claim 31, wherein each transducer is adapted to detect a respective beacon signal when the beacon is at each respective location, and to subsequently output the time-reversed signal, responsive to the respective beacon signals from the beacon at each respective location and responsive to a position of the cardiac tissue.

34. Apparatus according to claim 33, wherein the beacon comprises a location sensor, adapted to generate a respective location signal responsive to a respective location of the beacon, and wherein each transducer is adapted to output the time-reversed signal responsive to the location signals.

35. Apparatus according to claim 33, wherein the one or more transducers comprise a plurality of ultrasound transducers, adapted to output the time-reversed signals responsive to the position of the cardiac tissue and reversed in time with respect to a sequence of detecting, at the plurality of transducers, the beacon signal when the beacon is at each location.

36. Apparatus according to claim 33, wherein each transducer is adapted to regulate a timing parameter of the outputting of the time-reversed signal, responsive to a position of the transducer, a position of the beacon when the beacon is at each location, and the position of the cardiac tissue.

37. A method for performing ablation of cardiac tissue using ultrasound, comprising:

detecting, at one or more detection locations, respective beacon signals coming from a beacon placed at a cardiac site in a body of a subject;

reversing each of the beacon signals with respect to a time-based property thereof, to obtain respective time-reversed ultrasound signals; and

generating the respective time-reversed ultrasound signals at each of the one or more locations, at a level sufficient to ablate the cardiac tissue.

38. A method according to claim 37, wherein detecting at the one or more detection locations comprises detecting at one or more locations on an external surface of the body of the subject.

39. A method according to claim 37, wherein reversing each of the beacon signals comprises reversing each of the beacon signals with respect to the time-based property thereof and a shape-based property thereof, to obtain the respective time-reversed signals.

40. A method according to claim 37, wherein generating the time-reversed signals comprises amplifying the time-reversed signals.

41. A method according to claim 37, wherein detecting the respective beacon signals comprises placing the beacon at the cardiac site using a cardiac map of at least a portion of a heart of the subject.

42. A method according to claim 37, wherein detecting the respective beacon signals at the one or more detection locations comprises detecting a single beacon signal at a single detection location, and wherein reversing each of the beacon signals comprises reversing the single beacon signal with respect to the time-based property thereof.

43. A method according to claim 37, wherein detecting the respective beacon signals at the one or more detection locations comprises detecting a plurality of respective beacon signals at a plurality of respective detection locations, and wherein reversing each of the beacon signals comprises reversing each of the beacon signals with respect to a sequence of detecting, at the plurality of respective detection locations, the plurality of respective beacon signals.

44. A method according to claim 37, wherein generating the time-reversed signals at each of the one or more detection locations comprises regulating a timing parameter of generating the time-reversed signals at each of the one or more detection locations, responsive to a position of the respective detection location, a position of the beacon, and a position of the cardiac tissue.

45. A method according to claim 37, wherein the beacon is affixed in a vicinity of a distal end of a catheter inserted into the body and brought to the cardiac site, and wherein detecting the respective beacon signals comprises detecting the respective beacon signals coming from the beacon when it is affixed to the catheter.

46. A method according to claim 37, wherein generating the time-reversed signals comprises configuring the time-reversed signals to be such as to form one or more non-conducting lesions in the cardiac tissue.

47. A method according to claim 46, comprising identifying that the cardiac tissue generates undesired electrical signals.

48. A method according to claim 46, comprising identifying that undesired electrical signals, initially generated at a site outside the cardiac tissue, propagate through the cardiac tissue.

49. A method according to claim 37, wherein the cardiac site is in a vicinity of a pulmonary vein of the subject, and wherein detecting the respective beacon signals comprises detecting the respective beacon signals coming from the beacon when the beacon is in the vicinity of the pulmonary vein.

50. A method according to claim 49, wherein the cardiac site is in a vicinity of an ostium of the pulmonary vein, and wherein detecting the respective beacon signals comprises detecting the respective beacon signals coming from the beacon when the beacon is in the vicinity of the ostium.

51. A method according to claim 37,

wherein the beacon includes a passive beacon, and

wherein detecting the respective beacon signals comprises illuminating the passive beacon with an illuminating ultrasound signal, and detecting respective ultrasound echo signals coming from the passive beacon, responsive to the illuminating.

52. A method according to claim 51, wherein the passive beacon is characterized by higher ultrasound reflectivity than a natural level of ultrasound reflectivity at the cardiac site, and wherein detecting the respective echo signals comprises detecting the respective echo signals coming from the passive beacon, responsive to the higher ultrasound reflectivity.

53. A method according to claim 51, wherein the passive beacon is of a geometry that produces a distinguishable signature in the echo signals when the beacon is illuminated with the illuminating signal, and wherein detecting the respective echo signals comprises detecting the signature in the respective echo signals.

54. A method according to claim 51, wherein the passive beacon includes a crystal having a predefined resonance frequency, wherein illuminating the passive beacon comprises illuminating with the illuminating signal at the resonance frequency, and wherein detecting the respective echo signals comprises detecting the respective echo signals coming from the passive beacon, responsive to illuminating with the illuminating signal at the resonance frequency.

55. A method according to claim 51, wherein the passive beacon includes an ultrasound contrast agent that reflects a known harmonic of the illuminating signal, and wherein detecting the respective echo signals comprises detecting the known harmonic, responsive to illuminating with the illuminating signal.

56. A method according to claim 37, comprising transducing, by the beacon, energy received by the beacon so as to generate the respective beacon signals.

57. A method according to claim 56, wherein the respective beacon signals are characterized by one or more generally omnidirectional pulses, and wherein transducing the received energy comprises transducing the received energy so as to generate the generally omnidirectional pulses.

58. A method according to claim 56, comprising transmitting the energy to the beacon through a set of one or more wires connected to the beacon.

59. A method according to claim 56, comprising wirelessly transmitting the energy to the beacon.

60. A method according to claim 59, wherein the energy includes ultrasound energy, and wherein wirelessly transmitting the energy comprises wirelessly transmitting the ultrasound energy to the beacon.

61. A method according to claim 59, wherein the energy includes electromagnetic energy, and wherein wirelessly transmitting the energy comprises wirelessly transmitting the electromagnetic energy to the beacon.

62. A method according to claim 37, wherein detecting the respective beacon signals comprises detecting each respective beacon signal when the beacon is placed in sequence at a plurality of respective beacon locations in a vicinity of the cardiac site.

63. A method according to claim 62, wherein detecting the respective beacon signals comprises detecting the respective beacon signals when the beacon is placed in sequence at the plurality of beacon locations, such beacon locations including at least four non-coplanar beacon locations.

64. A method according to claim 62, wherein detecting the respective beacon signals comprises detecting each respective beacon signal when the beacon is at each respective beacon location, and wherein generating the time-reversed signals comprises subsequently generating the time-reversed signals, responsive to the respective beacon signals from the beacon at each beacon location and responsive to a position of the cardiac tissue.

65. A method according to claim 64, wherein generating the time-reversed signals comprises generating the time-reversed signals responsive to a respective beacon position signal generated by the beacon at each respective beacon location.

66. A method according to claim 64, wherein detecting the respective beacon signals at the one or more detection locations comprises detecting a plurality of beacon signals at a respective plurality of detection locations, and wherein reversing each of the beacon signals comprises reversing each of the beacon signals responsive to the position of the cardiac tissue and with respect to a sequence of detecting, at the plurality of detection locations, the respective plurality of beacon signals.

67. A method according to claim 64, wherein generating the time-reversed signals at each of the one or more detection locations comprises regulating a timing parameter of the generation of the time-reversed signal, responsive to a position of each respective detection location, a position of the beacon when the beacon is at each beacon location, and the position of the cardiac tissue.