Ultrasound catheter with cavitation promoting surface

• US 20060264809A1
• Filed: 04/12/2006
• Published: 11/23/2006
• Est. Priority Date: 04/12/2005
• Status: Abandoned Application

• Current Assignee: EKOS Corporation (Boston Scientific Corporation)
• Original Assignee: EKOS Corporation (Boston Scientific Corporation)
• Inventors: Soltani, Azita, Hansmann, Douglas R.
• Application Number:
  US11/402,626
• Publication Number:
  US 20060264809A1
• Time in Patent Office: Days
• US Class Current: 604/22
• CPC Class Codes: A61B 17/22 Implements for squeezing-off ulcers or the like on the inside of inner organs of the body; Implements for scraping-out cavities of body organs, e.g. bones; Calculus removers; Calculus smashing apparatus; Apparatus for removing obstructions in blood vessels, not otherwise provided for dilators A61M29/00
• 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 2017/00154 pulsed
• CPC Class Codes: A61B 2017/22008 used or promoted
• CPC Class Codes: A61B 2017/22088 ultrasound absorbing, drug activated by ultrasound
• CPC Class Codes: A61M 37/0092 using ultrasonic, sonic or infrasonic vibrations, e.g. phonophoresis
• CPC Class Codes: A61N 2007/0039 using microbubbles
• CPC Class Codes: A61N 7/00 Ultrasound therapy lithotripsy A61B17/22, A61B17/225; massage using supersonic vibration A61H23/00 ; using ultrasound for introducing media into the body A61M37/0092

Abstract

In one embodiment of the present invention, a method of applying ultrasonic energy to a treatment site within a patient'"'"'s vasculature comprises positioning an ultrasound radiating member at a treatment site within a patient'"'"'s vasculature. The method further comprises activating the ultrasound radiating member to produce pulses of ultrasonic energy at a cycle period T≦1 second. Each pulse of ultrasonic energy has a first peak amplitude for a first duration, and a second reduced amplitude that is less than the first peak amplitude for a second duration.

Claims

1. A method of applying ultrasonic energy to a treatment site within a patient'"'"'s vasculature, the method comprising:

positioning an ultrasound radiating member at a treatment site within a patient'"'"'s vasculature; and

activating the ultrasound radiating member to produce pulses of ultrasonic energy at a cycle period T≦

1 second, wherein each pulse of ultrasonic energy has a first peak amplitude for a first duration, and a second reduced amplitude that is less than the first peak amplitude for a second duration.

2. The method of claim 1, further comprising positioning a cavitation promoting surface at the treatment site, such that the cavitation promoting surface is present at the treatment site when the ultrasound radiating member is activated.

3. The method of claim 1, wherein at least a portion of the second duration occurs before the first duration is initiated.

4. The method of claim 1, wherein the ultrasound radiating member is movable with respect to a catheter sheath that is positioned at the treatment site.

5. The method of claim 1, further comprising delivering a therapeutic compound to the treatment site concurrently with the ultrasonic energy.

6. The method of claim 1, wherein the ultrasound radiating member operates with an acoustic efficiency greater than about 50%.

7. The method of claim 1, wherein the first peak amplitude induces cavitation at the treatment site.

8. The method of claim 1, wherein the first duration is shorter than the second duration.

9. The method of claim 1, wherein the pulses of ultrasonic energy have a duty cycle that is between about 1% and about 50%.

10. The method of claim 9, further comprising:

measuring a temperature at the treatment site; and

adjusting the duty cycle based on the temperature measurement.

11. A method comprising:

positioning an ultrasound radiating member at a treatment site within a patient'"'"'s vasculature;

delivering pulses of ultrasonic energy to the treatment site from the ultrasound radiating member, wherein the pulses of ultrasonic energy include a variable amplitude, such that the pulses have an increased pulse amplitude during a first pulse segment, and a reduced pulse amplitude during a second pulse segment; and

delivering a therapeutic compound to the treatment site simultaneously with the delivery of the pulses of ultrasonic energy.

12. The method of claim 11, wherein the first pulse segment occurs before the second pulse segment.

13. The method of claim 11, wherein the second pulse segment occurs before the first pulse segment.

14. The method of claim 11, wherein the pulses have a pulse amplitude that varies linearly between the increased pulse amplitude and the reduced pulse amplitude.

15. The method of claim 11, wherein the pulses have a cycle period T≦

1 second.

16. The method of claim 15, wherein the sum of a duration of the first pulse segment and a duration of the second pulse segment is between about 5% and about 25% of the cycle period T.

17. The method of claim 11, wherein:

a plurality of ultrasound radiating members are positioned at the treatment site;

a first ultrasonic waveform is delivered from a first ultrasound radiating member to the treatment site; and

a second ultrasonic waveform is delivered from a second ultrasound radiating member to the treatment site.

18. The method of claim 17, wherein the first ultrasonic waveform and the second ultrasonic waveform are delivered to the treatment site simultaneously.

19. A method comprising:

positioning a catheter at a treatment site within a patient'"'"'s vasculature, the catheter being positioned at least partially within an occlusion at the treatment site;

delivering a therapeutic compound from the catheter to the occlusion; and

delivering a plurality of packets ultrasonic energy from an ultrasound radiating member positioned within the catheter to the occlusion, wherein the packets of ultrasonic energy comprise a plurality of pulses of ultrasonic energy having an amplitude that varies pulse-to-pulse.

20. The method of claim 19, wherein the catheter includes a cavitation promoting surface that is exposed to the packets of ultrasonic energy

21. The method of claim 19, wherein the packets of ultrasonic energy are temporally separated by a period wherein substantially no ultrasonic energy is delivered to the treatment site.

22. The method of claim 19, wherein the plurality of pulses of ultrasonic energy have an amplitude that varies sinusoidally from pulse-to-pulse.

23. The method of claim 19, wherein the plurality of pulses of ultrasonic energy includes at least one trigger pulse having sufficient power to induce cavitation at the treatment site.

24. The method of claim 19, further comprising measuring a temperature at the treatment site after at least one of the packets of ultrasonic energy is delievered to the occlusion.

25. The method of claim 24, further comprising modifying the amplitude of the plurality of pulses of ultrasonic energy in response to the temperature measurement.

26. The method of claim 19, wherein the ultrasound radiating member is movable with respect to the catheter.

27. An ultrasound catheter configured to be inserted into a patient'"'"'s vascular system, the catheter comprising:

an elongate outer sheath defining a central lumen that extends longitudinally from an outer sheath proximal region to an outer sheath distal region;

an elongate hollow inner core positioned in the central lumen, the inner core defining a utility lumen; and

a ultrasound radiating member having a hollow inner passage through which the inner core passes, wherein the ultrasound radiating member is positioned generally between the inner core and the outer sheath;

wherein the outer sheath includes an outer surface, the outer sheath outer surface having

a cavitation promoting region located adjacent to the ultrasound radiating member, and

a smooth region located proximal to the cavitation promotion region, wherein the cavitation promoting region has an increased surface roughness as compared to the smooth region.

28. The ultrasound catheter of claim 27, wherein the elongate outer sheath has an outer diameter of less than about 5.2 French.

29. A catheter system for delivering ultrasonic energy and a therapeutic compound to a treatment site within a body lumen, the catheter system comprising:

a tubular body having

a proximal end,

a distal end, and

an energy delivery section positioned between the proximal end and the distal end, wherein the energy delivery section includes a cavitation promoting surface having an increased surface roughness;

a fluid delivery lumen extending at least partially through the tubular body and having at least one outlet in the energy delivery section;

an inner core configured for insertion into the tubular body, the inner core comprising a plurality of ultrasound radiating members connected to an elongate electrical conductor; and

wiring such that a voltage can be applied from the elongate electrical conductor across a selected plurality of the ultrasound radiating members, such that the selected plurality of ultrasound radiating members can be driven simultaneously.

30. A method of treating a vascular occlusion, the method comprising:

delivering a catheter with a plurality of ultrasound radiating members to a treatment site within a patient'"'"'s vasculature, wherein;

the vascular occlusion is located at the treatment site and

the catheter includes a cavitation promoting surface region having an increased surface roughness as compared to surface regions adjacent the cavitation promoting surface region; and

delivering ultrasonic energy to the treatment site from the catheter so as to generate cavitation at the treatment site.

31. The method of claim 30, further comprising delivering an ultrasound contrast agent to the treatment site.

32. The method of claim 30, wherein the ultrasonic energy has a duty cycle that is between about 1% and about 10%.

33. The method of claim 30, wherein the ultrasonic energy has a frequency that is between about 1.2 MHz and about 2.2 MHz.

34. The method of claim 30, wherein the ultrasonic energy has a peak acoustic pressure that is between about 1.8 MPa and about 3.8 MPa.

35. The method of claim 30, wherein the ultrasonic energy has a spatial average acoustic pressure that is preferably between about 1.4 MPa and about 3.4 MPa.

36. An ultrasound catheter comprising:

an elongate tubular body having a proximal region and a distal region, wherein an energy delivery section is included within the distal region of the tubular body;

an ultrasound radiating member positioned adjacent to the energy delivery section of the elongate tubular body;

a cavitation promoting surface that is formed on an exterior surface of the ultrasound catheter, and that is exposed to ultrasonic energy when the ultrasound radiating member is activated;

a fluid delivery lumen positioned within the elongate tubular body; and

a fluid delivery port that is configured to deliver a fluid within the fluid delivery lumen to an exterior region of the ultrasound catheter that is adjacent to the cavitation promoting surface.

37. The ultrasound catheter of claim 36, wherein the fluid delivery lumen passes through a hollow inner core of the ultrasound radiating member.

38. The ultrasound catheter of claim 36, wherein the fluid delivery port is positioned at a distal end of the elongate tubular body.

39. The ultrasound catheter of claim 36, wherein the fluid delivery port is positioned on the exterior surface of the ultrasound catheter.

40. The ultrasound catheter of claim 36, wherein the fluid delivery port is positioned on the cavitation promoting surface.

41. The ultrasound catheter of claim 36, wherein when the ultrasound radiating member is activated, cavitation occurs adjacent to the cavitation promoting surface, but does not occur adjacent to other regions of the catheter.

42. The ultrasound catheter of claim 36, wherein the cavitation promoting surface is configured to entrap gas pockets thereon when immersed in a liquid.

43. A catheter system comprising:

an elongate tubular body having a distal region and a proximal region opposite the distal region;

an ultrasound radiating member positioned adjacent to the distal region of the elongate tubular body;

a fluid delivery lumen extending through at least a portion of the elongate tubular body;

a fluid delivery port that is configured to deliver a fluid within the fluid delivery lumen to a region exterior to the elongate tubular body; and

a control system configured to provide a control signal to the ultrasound radiating member, wherein the control signal causes the ultrasound radiating member to generate a plurality of pulses of ultrasonic energy, and wherein a first pulse of ultrasonic energy has an amplitude that is greater than a second pulse of ultrasonic energy.

44. The catheter system of claim 43, further comprising a cavitation promoting surface that is exposed to ultrasonic energy when the control signal is provided to the ultrasound radiating member.

45. The catheter system of claim 44, wherein the control signal is configured to cause cavitation in a region adjacent to the cavitation promoting surface, but to not cause cavitation adjacent to other regions of the catheter.

46. The catheter system of claim 44, wherein the cavitation promoting surface is configured to entrap gas pockets thereon when immersed in a liquid.

47. The catheter system of claim 43, wherein the plurality of pulses of ultrasonic energy have an amplitude that varies sinusoidally from pulse-to-pulse.

48. The catheter system of claim 43, wherein the first pulse of ultrasonic energy has a peak power of greater than about 15 watts.

49. The catheter system of claim 43, further comprising a temperature sensor, wherein the control system is configured to modify the control signal based on a temperature signal generated by the temperature sensor.

55. The catheter system of claim 43, wherein the first peak amplitude has a peak power of greater than about 15 watts.

56. The catheter system of claim 43, further comprising a temperature sensor, wherein the control system is configured to modify the control signal based on a temperature signal generated by the temperature sensor.

50. A catheter system comprising:

an elongate tubular body having a distal region and a proximal region opposite the distal region;

an ultrasound radiating member positioned adjacent to the distal region of the elongate tubular body;

a fluid delivery lumen extending through at least a portion of the elongate tubular body;

a fluid delivery port that is configured to deliver a fluid within the fluid delivery lumen to a region exterior to the elongate tubular body; and

a control system configured to provide a control signal to the ultrasound radiating member, wherein the control signal causes the ultrasound radiating member to generate pulses of ultrasonic energy at a cycle period T≦

1 second, wherein a selected pulse of ultrasonic energy has

a first peak amplitude for a first duration, and a second reduced amplitude that is less than the first peak amplitude for a second duration.

51. The catheter system of claim 50, further comprising a cavitation promoting surface that is exposed to ultrasonic energy when the control signal is provided to the ultrasound radiating member.

52. The catheter system of claim 51, wherein the control signal is configured to cause cavitation in a region adjacent to the cavitation promoting surface, but to not cause cavitation adjacent to other regions of the catheter.

53. The catheter system of claim 51, wherein the cavitation promoting surface is configured to entrap gas pockets thereon when immersed in a liquid.

54. The catheter system of claim 50, wherein at least a portion of the second duration occurs before the first duration is initiated.