CARDIAC ABLATION CATHETERS FOR FORMING OVERLAPPING LESIONS

• US 20090299354A1
• Filed: 04/14/2009
• Published: 12/03/2009
• Est. Priority Date: 07/14/1999
• Status: Active Grant

• Current Assignee: Cardiofocus Incorporated
• Original Assignee: Cardiofocus Incorporated
• Inventors: Melsky, Gerald, Baxter, Lincoln S., Arnold, Jeffrey M., Sagon, Stephen W., Stancampiano, Alfred
• Granted Patent: US 9,033,961 B2
• Time in Patent Office: Days
• US Class Current: 606/16
• 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: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00

Abstract

Methods and instruments are disclosed for creating lesions in tissue, especially cardiac tissue, for treatment of arrhythmias and the like, by employing an elastic balloon and an energy emitter, which is independently positionable within the lumen of the instrument and adapted to project a series of spots of ablative energy through a transmissive region of the balloon to a target tissue site. The energy emitter preferably is configured such the spots of energy result in a series of lesions formed in the target tissue region when the emitter is activated, the lesions having an average area ranging from about 5 mm² to about 100 mm². In one aspect of the invention, percutaneous ablation instruments are disclosed in the form of catheter bodies having one or more balloon structures at the distal end region of the instrument and an energy emitting element, which is independently positionable and rotatable within a lumen of the instrument and adapted to project ablative energy through a transmissive region of the balloon to a target tissue site in contact with, or proximal to, the balloon surface.

Claims

1. A cardiac tissue ablation system, comprising:

an elongate catheter configured to deliver a distal end thereof to a patient'"'"'s heart;

an expandable member formed at the distal portion of the catheter, the expandable member having an elastic portion configured to conform to the shape of a target tissue region upon expansion; and

an energy emitter movably disposed within a lumen of the catheter, the energy emitter configured to deliver a series of spots of radiant ablative energy to the target tissue region.

2. The system of claim 1, wherein the energy emitter is configured such that the spots of energy result in a series of lesions formed in the target tissue region when the emitter is activated, the lesions having an average area ranging from about 5 mm² to about 100 mm².

3. The system of claim 2, wherein the energy emitter is configured to form arc shaped lesions in the target tissue region subtending an angle ranging from about 5 degrees to about 45 degrees relative to the emitter.

4. The system of claim 2, wherein the energy emitter is configured to form arc shaped lesions in the target tissue region subtending an angle of less than about 30 degrees relative to the emitter.

5. The system of claim 1, wherein the energy emitter is slidably and rotatably disposed within an inner lumen of the catheter thereby allowing the energy emitter to effectively ablate any of a plurality of regions within the target tissue area.

6. The system of claim 1, wherein the energy emitter is configured to project energy toward the target tissue area at an angle ranging from about 5 degrees to about 110 degrees relative to a longitudinal axis of the catheter.

7. The system of claim 1, wherein the energy emitter is configured to project energy toward the target tissue area at an angle ranging from about 60 to about 90 degrees relative to a longitudinal axis of the catheter.

8. The system of claim 6, wherein the energy emitter includes a reflector element coupled to a distal end of the energy emitter.

9. The system of claim 8, wherein the reflector element is a quartz reflector.

10. The system of claim 1, wherein the energy emitter includes an optic fiber with a grin lens coupled to a distal end of the fiber, the energy emitter further having a reflector element positioned distal of the grins lens, the reflector element configured to deliver ablative energy to the cardiac tissue at an angle of about 900 relative to a longitudinal axis of the catheter.

11. The system of claim 1, further including an endoscope configured to allow direct visualization of the tissue treatment area.

12. The system of claim 1, wherein the expandable member includes a plurality of markers defining a number of power-level segments, each power-level segment corresponding to an amount of ablation energy to be delivered to the segment by the energy emitter.

13. The system of claim 10 that further includes at least one radiopaque marker visible via x-ray imaging shaped in such a manner as to allow the determination of the rotational orientation of the expandable member relative to the patients anatomy.

15. The system of claim 1, wherein the expandable member is a blunt-nosed balloon configured to impede passage of the balloon into a pulmonary vein when the balloon is deployed in proximity to the vein.

16. The system of claim 1, wherein the expandable member is a balloon with a tapered distal end that impedes passage of the balloon into a pulmonary vein when the balloon is deployed in proximity to the vein.

17. The system of claim 1 wherein the expandable member is a balloon whose distal portion gradually decreases in diameter.

19. The system of claim 13, wherein the spot energy emitter is configured to project radiant energy to the target tissue area at an angle of about 90°

or less relative to a longitudinal axis of the catheter.

20. The system if claim 13, wherein the spot lesion is an arc shaped lesion subtending an angle of less than about 30°

relative to the emitter.

14. The system of claim 14 wherein the radiopaque marker resides at a know location relative to the view seen in the endoscope such that the orientation of the patients anatomy relative to the endoscopic view may be determined.

18. A cardiac ablation system, comprising:

a cardiac ablation catheter having an expandable member formed on a distal end thereof, the expandable member formed of an elastic material such that the expandable member conforms to a shape and contour of a target tissue area during expansion of the expandable member; and

a spot energy emitter movably disposed within an inner lumen of the catheter, the spot energy emitter configured to deliver ablative energy to the target tissue area thereby forming a spot lesion in the target tissue area.

21. A method for treating a cardiac condition, comprising:

delivering an expanding member formed on a distal end of a catheter to a position adjacent a tissue treatment area within a patient'"'"'s heart, the expandable member having an elastic portion configured to conform to the tissue treatment area;

expanding the expandable member thereby allowing the elastic portion of the expandable member to conform to the tissue treatment area;

positioning an energy emitter at a first location within an inner lumen of the catheter; and

delivering a first spot of energy from the energy emitter to the tissue treatment area thereby resulting in a first spot lesion.

22. The method of claim 21, further comprising positioning the energy emitter at a second location within the inner lumen of the catheter, and delivering a second spot of energy from the energy emitter to the tissue treatment area thereby resulting in a second spot lesion, wherein the second spot lesion intersects the first spot lesion.

23. The method of claim 22, further comprising repeating the positioning step and the delivering step until a plurality of spot lesions are provided which form a substantially circumferential lesion.

24. The method of claim 23, wherein the circumferential lesion encircles an ostium of a pulmonary vein.

25. The method of claim 24, wherein the cardiac condition is atrial fibrillation

26. The method of claim 21, wherein each spot lesion is formed in the shape of an arc that subtends an angle ranging from about 5 degrees to about 45 degrees relative to the emitter.

27. The method of claim 21, wherein each spot lesion is formed in the shape of an arc that subtends an angle less than about 30 degrees relative to the emitter.

28. The method of claim of claim 21 wherein the method further comprises observing balloon location via an endoscope deployed within the catheter.

29. The method of claim of claim 28 wherein the method further comprises observing a marker on the balloon to determine balloon orientation within the heart.

30. The method of claim of claim 21 wherein the method further comprises projecting an aiming beam during positioning of the energy emitter to identify a candidate site for treatment.

31. The method of claim 30 wherein the method further comprises verifying that a candidate site is acceptable for ablation by endoscopic observation of the aiming beam.

32. The method of claim 31 wherein the verification is based on endoscopic observation of balloon contact with tissue in the vicinity of the aiming beam impingement.

33. The method of claim 30 wherein the verification is based on endoscopic observation of a lack of balloon contact with blood in the vicinity of the aiming beam impingement.

34. The method of claim of claim 21 wherein the method further comprises selecting a dose for forming a spot lesion based on endoscopic observation following expansion of the expandable member and positioning of the energy emitter.

35. The method of claim of claim 34 wherein the method further comprises selecting a dose based on an observed size of an impingement spot of an aiming beam.

36. The method of claim of claim 34 wherein the method further comprises selecting a dose based on an observed balloon location.

37. The method of claim of claim 21 wherein the method further comprises forming a first spot lesion and then repositioning the energy emitter to a second location.

38. The method of claim 37 wherein the method further comprises verifying a second candidate site is acceptable for ablation by endoscopic observation of a aiming beam during repositioning of the energy emitter.

39. The method of claim 38 wherein the method further comprises verifying that a second or subsequent candidate site is suitable to forming a subsequent lesion that will be contiguous with the first lesion.

40. An instrument for cardiac ablation comprising an elongated optical fiber capable of transmitting ablative radiation and a distal light projection assembly, the assembly further comprising a body for encasing a distal end portion of the fiber and a reflector for redirecting radiant energy travelling through the fiber at angle relative to the longitudinal axis of the fiber.

41. The instrument of claim 40 wherein a distal end face of the optical fiber is beveled to a distal output face of reduced cross-sectional area.

42. The instrument of claim 41 wherein the output face is generally rectangular.

43. The instrument of claim 40 wherein the distal light projecting assembly further comprises a lens configured to receive radiant energy from a distal output face of the optical fiber and focus the energy prior to redirection by the reflector.

44. The instrument of claim 43 wherein the lens further comprises at least one graded refractive index lens.

45. The instrument of claim 40 wherein the distal end portion of the optical fiber is beveled to a distal output face of reduced cross-sectional area and the distal light projecting assembly further comprises a lens configured to receive radiant energy from the distal output face of the optical fiber and focus the energy prior to redirection by the reflector.

46. The instrument of claim 45 wherein the beveled output face of the optical fiber is rectangular and is offset from an optical axis of the lens such that the radiant energy is projected as an arc shaped beam.

47. The instrument of claim 46 wherein the instrument is further configured to project a beam of radiant energy in the shape of an arc that subtends an angle less than about 30 degrees.