Coaxial catheter instruments for ablation with radiant energy

• US 20040006333A1
• Filed: 02/03/2003
• Published: 01/08/2004
• Est. Priority Date: 09/09/1994
• Status: Active Grant

• Current Assignee: Cardiofocus Incorporated
• Original Assignee: Cardiofocus Incorporated
• Inventors: Farr, Norman E., Baxter, Lincoln S., Arnold, Jeffrey M., Sinofsky, Edward L.
• Granted Patent: US 8,025,661 B2
• Time in Patent Office: Days
• US Class Current: 606/15
• CPC Class Codes: A61B 18/24 with a catheter A61B18/26, A61B18/28 take precedence
• CPC Class Codes: A61B 18/245 for removing obstructions in blood vessels or calculi
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61B 2017/00061 spectrum
• CPC Class Codes: A61B 2018/0097 Cleaning probe surfaces
• CPC Class Codes: A61B 2018/2261 with scattering, diffusion or dispersion of light
• CPC Class Codes: A61B 2018/2266 with a lens, e.g. ball tipped
• CPC Class Codes: A61B 2018/2272 with reflective or refractive surfaces for deflecting the beam A61B2018/2261, A61B2018/2266 take precedence
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61L 2/10 Ultraviolet radiation
• CPC Class Codes: A61L 29/085 Macromolecular materials
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: C08L 27/12 containing fluorine atoms

Abstract

Ablation methods and instruments are disclosed for creating lesions in tissue, especially cardiac tissue for treatment of arrhythmias and the like. Percutaneous ablation instruments in the form of coaxial catheter bodies are disclosed having at least one central lumen therein and having one or more balloon structures at the distal end region of the instrument. The instruments include an energy emitting element which is independently positionable within the lumen of the instrument and adapted to project radiant energy through a transmissive region of a projection balloon to a target tissue site. The instrument can optionally include at least one expandable anchor balloon disposed about, or incorporated into an inner catheter body designed to be slid over a guidewire. This anchor balloon can serve to position the device within a lumen, such as a pulmonary vein. A projection balloon structure is also disclosed that can be slid over the first (anchor balloon) catheter body and inflated within the heart, to define a staging from which to project radiant energy. An ablative fluid can also be employed outside of the instrument (e.g., between the balloon and the target region) to ensure efficient transmission of the radiant energy when the instrument is deployed. In another aspect of the invention, generally applicable to a wide range of cardiac ablation instruments, mechanisms are disclosed for determining whether the instrument has been properly seated within the heart, e.g., whether the device is in contact with a pulmonary vein and/or the atrial surface, in order to form a lesion by heating, cooling or projecting energy. This contact-sensing feature can be implemented by an illumination source situated within the instrument and an optical detector that monitors the level of reflected light. Measurements of the reflected light (or wavelengths of the reflected light) can thus be used to determine whether contact has been achieved and whether such contact is continuous over a desired ablation path.

Claims

1. A cardiac ablation instrument comprising:

a catheter body adapted for disposition within a heart having at least one lumen therein, which body can be deployed at a desired location within the heart; and

an energy emitter movable within a lumen of the catheter body such that it can be disposed at the desired location and deliver ablative energy to a target tissue site.

2. The instrument of claim 1, wherein the energy emitter is slidably disposed within a lumen of the catheter body and the instrument further comprises a translatory mechanism for positioning the emitter at a selected location within the catheter body.

3. The instrument of claim 1, wherein the energy emitter is a radiant energy emitter.

4. The instrument of claim 1, wherein the energy emitter projects a ring of radiant ablative energy of variable diameter based on its axial position within the catheter body.

5. The instrument of claim 3 wherein the catheter body further comprises a projection balloon.

6. The instrument of claim 5 wherein the catheter body further comprises a projection balloon adapted for inflation in proximity to a pulmonary vein ostium to provide a transmission pathway for radiant energy.

7. The instrument of claim 3, wherein the radiant energy emitter further comprises a light transmitting optical fiber adapted to receive radiant energy from a light source and a light emitting tip at a distal end of the fiber for emitting light.

8. The instrument of claim 7, wherein the light emitting tip further comprises a beam forming optical waveguide for projecting an annular beam of light, such that the radiant energy emitter projects a ring of ablative energy of variable diameter based on its axial position within the catheter body.

9. The instrument of claim 3 wherein the instrument further comprises a light source for generating photoablative radiation at desired wavelengths ranging from between about 800 nm and about 1000 nm.

10. The instrument of claim 3, wherein the instrument further comprises a light source for generating photoablative radiation at a desired wavelength ranging from about 915 nm to about 980 nm.

11. The instrument of claim 3, wherein the energy emitter comprises an ultrasound generator.

12. The instrument of claim 11, wherein the ultrasound generator generates ultrasound energy at at least one wavelength in the range of about 5 to about 20 MHz.

13. The instrument of claim 11, wherein the ultrasound generator generates ultrasound energy at at least one wavelength in the range of about 7 to about 10 MHz.

14. The instrument of claim 3, wherein the energy emitter comprises a microwave generator.

15. The instrument of claim 5, wherein the instrument further comprises a contact sensor for sensing contact between the projection balloon and target tissue.

16. The instrument of claim 15, wherein the contact sensor further comprises a contact sensing element movable within a lumen of the catheter body such that it can be disposed at various locations to detect reflected radiant energy and, based on the reflected energy, select a desired location for forming a lesion.

17. The instrument of claim 15, wherein the reflectance sensor further comprises a light detector for detecting reflected light energy.

18. The instrument of claim 15, wherein the reflectance sensor further comprises an ultrasound detector for detecting reflected ultrasound energy.

19. A cardiac ablation instrument comprising:

a catheter body adapted for disposition within a heart having at least one lumen therein; and

a contact sensing element movable within a lumen of the catheter body such that it can be disposed at various locations to detect reflected radiant energy and, based on the reflected energy, select a desired location for forming a lesion.

20. The instrument of claim 19, wherein the contact sensing element further comprises a light detector for detecting reflected light energy.

21. The instrument of claim 19, wherein the contact sensing element further comprises an ultrasound detector for detecting reflected ultrasound energy.

22. The instrument of claim 19 wherein the instrument further comprises a projection balloon for clearing a transmission pathway for radiant energy from an energy emitter to a target treatment site.

23. The instrument of claim 19 wherein the instrument further comprises at least one optical sensor within the instrument for receiving reflected light.

24. The instrument of claim 23 wherein the instrument further comprises a source of illumination for illuminating a region surrounding the instrument and inducing reflected light that can be collected by the optical sensor.

25. The instrument of claim 23 wherein the instrument further comprises a detector capable of distinguishing at least two wavelengths of reflected light.

26. The instrument of claim 19, wherein the instrument further comprises a radiant energy emitter that is slidably disposed within a lumen of the catheter body and the instrument further comprises a translatory mechanism for positioning the emitter at a selected location within the catheter body.

27. The instrument of claim 26, wherein the radiant energy emitter further comprises a light transmitting optical fiber adapted to receive radiant energy from a light source and beam forming optics at a distal end of the fiber for projecting an annular beam of light.

28. The instrument of claim 27, wherein the instrument further comprises a light source for generating photoablative radiation at desired wavelengths ranging from between about 800 nm and about 1000 nm

29. The instrument of claim 26, wherein the radiant energy emitter comprises an ultrasound generator.

30. The instrument of claim 26, wherein the radiant energy emitter comprises a microwave generator.

31. The instrument of claim 19 wherein the instrument further comprises an ablation element at the distal end of the catheter body.

32. The instrument of claim 31 wherein the ablation element is a contact heating element.

33. The instrument of claim 31 wherein the instrument further comprises an expandable element and the ablation element is coupled to at least a portion of the expandable element.

34. The instrument of claim 31 wherein the ablation element comprises at least one electrode adapted to couple to an electric current source.

35. The instrument of claim 34 wherein the electrode is coupled to a radio frequency electric current source.

36. The instrument of claim 31 wherein the ablation element is a cryogenic ablation element.

37. The instrument of claim 31 wherein the ablation element is an ultrasound ablation element.

38. The instrument of claim 31 wherein the ablation element is adapted to be positioned at a location where a pulmonary vein extends from an atrium.

39. The instrument of claim 19 wherein the contact sensor comprises at least one optic fiber for collecting reflected light.

40. The instrument of claim 19 wherein the contact sensor comprises a plurality of optic fibers for illuminating light to different directions.

41. A cardiac ablation instrument comprising:

a first catheter body adapted for disposition within a heart having at least one lumen therein and comprising at least one anchorage element which can be deployed at the desired location to contact a cardiac structure and secure the device in place; and

a radiant energy emitter movable within a lumen of the first catheter body such that it can be disposed at the desired location and deliver radiant energy through a transmissive region of the instrument to a target tissue site.

42. The instrument of claim 41 wherein the anchorage element is an anchor balloon adapted for inflation within a pulmonary vein to secure the instrument at a desired location.

43. The instrument of claim 41, wherein the radiant energy emitter is slidably disposed within a lumen of the first catheter body and the instrument further comprises a translatory mechanism for positioning the emitter at a selected location within the first catheter body.

44. The instrument of claim 41, wherein the radiant energy emitter further comprises a light transmitting optical fiber adapted to receive radiant energy from a light source and a light emitting tip at a distal end of the fiber for emitting light.

45. The instrument of claim 44, wherein the light emitting tip further comprises a beam forming optical waveguide for projecting an annular beam of light.

46. The instrument of claim 44, wherein the light emitting tip further comprises a light diffusing element.

47. The instrument of claim 44, wherein the instrument further comprises a light source for generating photoablative radiation at desired wavelengths ranging from between about 800 nm and about 1000 nm

48. The instrument of claim 44, wherein the instrument further comprises a light source for generating photoablative radiation at a desired wavelength ranging from about 915 nm to about 980 nm.

49. The instrument of claim 41, wherein the radiant energy emitter comprises an ultrasound generator.

50. The instrument of claim 41, wherein the radiant energy emitter comprises a microwave generator.

51. The instrument of claim 41 wherein the instrument further comprises a second catheter body with an inner channel, configured for coupling to the first catheter body via the channel such that the second catheter body can be passed over the first catheter body into a position within the heart, and having an inflatable projection balloon which be deployed to clear blood from a surrounding region within the heart.

52. The instrument of claim 41 wherein the instrument further comprises a contact sensor.

53. The instrument of claim 42 wherein the instrument further comprises at least one optical sensor within the instrument for receiving reflected light.

54. The instrument of claim 53 wherein the instrument further comprises a source of illumination for illuminating a region surrounding the instrument and inducing reflected light that can be collected by the optical sensor.

55. The instrument of claim 53 wherein the instrument further comprises a detector capable of distinguishing at least two wavelengths of reflected light.

56. A method of ablating cardiac tissue, comprising:

positioning a guide wire in proximity to a target region of cardiac tissue;

coupling a first catheter having at least one lumen to the positioned guide wire via the lumen such that the first catheter can be passed over the guide wire into a position within the heart;

removing the guide wire and replacing it with a radiant energy emitter slidable movable within a lumen of the first catheter such that it can be disposed at the desired location; and

activating the radiant energy emitter to deliver radiant energy through a transmissive region of the first catheter to the target tissue region to ablate tissue and form a conduction block.

57. The method of claim 56 wherein the step of activating the radiant energy emitter further comprises activating a light emitting element to expose the target region to light energy to induce photocoagulation of cardiac tissue within the target region.

58. The method of claim 57 wherein the step of activating the radiant energy emitter further comprises activating a light emitting element to expose the target region to light energy to induce a continuous lesion in the cardiac tissue.

59. The method of claim 57 wherein the step of activating the radiant energy emitter further comprises activating a light emitting element having a beam-forming optical waveguide to expose the target region to an annular beam of light energy to induce a circumferential lesion in cardiac tissue.

60. The method of claim 57, the step of activating the radiant energy emitter further comprises activating a light emitting element generating photoablative radiation at a desired wavelength ranging from about 800 nm to about 1000 nm

61. The method of claim 57, the step of activating the radiant energy emitter further comprises activating a light emitting element generating photoablative radiation at a desired wavelength ranging from about 915 nm to about 980 nm.

62. The method of claim 56, the step of activating the radiant energy emitter further comprises activating an ultrasound emitting element to expose the target region to acoustic energy to induce photocoagulation of cardiac tissue within the target region.

63. The method of claim 56, the step of activating the radiant energy emitter further comprises activating a radiation emitting element to expose the target region to at least one form of radiant energy selected from the group consisting of microwave, x-ray, gamma-ray and ionizing radiation to induce photocoagulation of cardiac tissue within the target region.

64. The method of claim 56 wherein the method further comprises inflating a projection balloon to clear blood from a transmission pathway between the energy emitter and a target region of cardiac tissue.

65. The method of claim 56 wherein the method further comprises determining whether a clear transmission path has been established between the radiant energy emitter and the target tissue based on reflectance measurements by an optical sensor disposed within the lumen of the first catheter.

66. The method of claim 65 wherein the method further comprises measuring at least two different wavelengths of reflected light collected by the optical sensor to determine whether a projection path exists.

67. A method of treating atrial fibrillation, comprising:

positioning a distal portion of an ablation instrument in proximity to one or more pulmonary veins, the instrument having a hollow housing and an independently positionable energy emitter within the distal portion, the distal portion being transmissive to radiant energy; and

activating the energy emitter to transmit energy through the housing to form an annular lesion in proximity to the one or more pulmonary veins.

68. The method of claim 67, the step of activating the radiant energy emitter further comprises activating a radiation emitting element to expose the target region to at least one form of radiant energy selected from the group consisting of light, ultrasound, microwave, x-ray, gamma-ray and ionizing radiation to induce photocoagulation of cardiac tissue within a target region.

69. The method of claim 67 wherein the method further comprises

inflating a projection balloon to clear blood from a transmission pathway between the energy emitter and a target region of cardiac tissue.

70. The method of claim 69 wherein the method further comprises determining whether a clear transmission path exists between the energy emitter and the target region based on reflectance measurements by an optical sensor disposed within the ablation instrument.

71. The method of claim 70 wherein the method further comprises measuring at least two different wavelengths of reflected light collected by the optical sensor to determine whether a projection path has been established.

72. The method of claim 67 wherein the step of activating the energy emitter further comprises activating a light emitting element to expose the target region to light energy to induce photocoagulation of cardiac tissue within the target region.

73. The method of claim 67 wherein the step of activating the radiant energy emitter further comprises activating a light emitting element to expose the target region to light energy to induce a continuous lesion in the cardiac tissue.

74. The method of claim 67 wherein the step of activating the energy emitter further comprises activating a light emitting element having a beam-forming optical waveguide to expose the target region to an annular beam of light energy to induce a circumferential lesion in cardiac tissue.

75. The method of claim 67, the step of activating the energy emitter further comprises activating a light emitting element generating photoablative radiation at a desired wavelength ranging from about 800 μ

m to about 1000 nm

76. The method of claim 67, the step of activating the energy emitter further comprises activating a light emitting element generating photoablative radiation at a desired wavelength ranging from about 915 nm to about 980 nm.

77. The method of claim 67, the step of activating the energy emitter further comprises activating an ultrasound emitting element to expose the target region to acoustic energy to induce photocoagulation of cardiac tissue within the target region.

78. The method of claim 67, the step of activating the energy emitter further comprises activating a radiation emitting element to expose the target region to at least one form of radiant energy selected from the group consisting of microwave, x-ray, gamma-ray and ionizing radiation to induce photocoagulation of cardiac tissue within the target region.