Method for reducing restenosis in the presence of an intravascular stent

• US 6,939,345 B2
• Filed: 03/26/2003
• Issued: 09/06/2005
• Est. Priority Date: 04/19/1999
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: KenKnight, Bruce H., Warren, Jay A., Hahn, Stephen John
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US10/397,623
• Publication Number:
  US 20030187340A1
• Time in Patent Office: 895 Days
• Field of Search: 606/32, 606/34, 606 41- 50, 606/192, 606/194, 606/196, 606/198, 600/372, 600/381
• US Class Current: 606/32
• 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 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/0022 Balloons
• CPC Class Codes: A61B 2018/00285 Balloons
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG

Abstract

A first electrode is positioned within an artery proximate an implanted intravascular stent. A second electrode is positioned at a separate location relative the position of the first electrode. Electrical energy is then delivered between the first and the second electrodes to produce an electrical field adjacent the implanted intravascular stent. When a intravascular stent is implanted in a coronary artery, the delivery of the electrical energy is coordinated to cardiac cycles detected in sensed cardiac signals, where the delivery of the electrical energy between the first electrode and the second electrode occurs during a predetermined portion of the cardiac cycle.

Claims

1. A method comprising:

positioning a first electrode near an implanted intravascular stent;

positioning a second electrode at a different position from the first electrode; and

delivering at least one pulse of electrical energy between the first and second electrodes at a repetition rate that is less than or equal to the order of a frequency between heart depolarizations.

2. The method of claim 1, wherein the positioning the second electrode includes positioning the second electrode at a remote position outside a lumen of the stent.

3. The method of claim 2, wherein the positioning the second electrode includes positioning the second electrode external to a patient.

4. The method of claim 3, wherein the positioning the second electrode includes positioning the second electrode on a dermal surface.

5. The method of claim 1, wherein the positioning the first electrode includes positioning the first electrode within a blood vessel.

6. The method of claim 5, wherein the positioning the first electrode includes positioning at least a portion of the first electrode within a lumen of stent.

7. The method of claim 5, wherein the positioning the first electrode includes positioning the first electrode within a lumen of the stent such that first and second electrode ends substantially align with respective first and second stent ends.

8. The method of claim 1, wherein positioning the first electrode includes positioning the first electrode on a catheter, and wherein the positioning the second electrode includes positioning the second electrode on the same catheter.

9. The method of claim 1, wherein at least one of the positioning the first electrode and the positioning the second electrode includes contacting one of the first and second electrodes with the stent.

10. The method of claim 1, further including sensing a cardiac signal, and wherein the delivering at least one pulse includes delivering the at least one pulse during a predetermined portion of a cardiac cycle.

11. The method of claim 1, in which the delivering at least one pulse includes discharging a capacitor.

12. The method of claim 1, in which the delivering at least one pulse includes delivering at least one substantially constant current pulse.

13. The method of claim 1, in which the delivering at least one pulse includes delivering at least one substantially direct current (DC) pulse.

14. The method of claim 1, in which the delivering at least one pulse includes delivering at least one pulse having a current density between about 1 ampere/cm² and about 4 amperes/cm².

15. The method of claim 1, in which the positioning the first electrode includes contacting the first electrode with the stent.

16. A method comprising:

positioning a first electrode near an implanted intravascular stent;

positioning a second electrode at a different position from the first electrode;

measuring an impedance between the first and second electrodes;

determining a desired energy level, using the measured impedance, for inhibiting or reducing stenosis; and

delivering electrical energy at the desired energy level between the first electrode and the second electrode to inhibit or reduce stenosis.

17. The method of claim 16, wherein the positioning the second electrode includes positioning the second electrode at a remote position outside a lumen of the stent.

18. The method of claim 17, wherein the positioning the second electrode includes positioning the second electrode external to a patient.

19. The method of claim 18, wherein the positioning the second electrode includes positioning the second electrode on a dermal surface.

20. The method of claim 16, wherein the positioning the first electrode includes positioning the first electrode within a blood vessel.

21. The method of claim 20, wherein the positioning the first electrode includes positioning at least a portion of the first electrode within a lumen of stent.

22. The method of claim 20, wherein the positioning the first electrode includes positioning the first electrode within a lumen of the stent such that first and second electrode ends substantially align with respective first and second stent ends.

23. The method of claim 16, wherein positioning the first electrode includes positioning the first electrode on a catheter, and wherein the positioning the second electrode includes positioning the second electrode on the same catheter.

24. The method of claim 16, wherein at least one of the positioning the first electrode and the positioning the second electrode includes contacting one of the first and second electrodes with the stent.

25. The method of claim 16, further including sensing a cardiac signal, and wherein the delivering electrical energy includes delivering at least one pulse during a predetermined portion of a cardiac cycle.

26. The method of claim 16, in which the delivering electrical energy includes discharging a capacitor.

27. The method of claim 16, in which the delivering electrical energy includes delivering at least one substantially constant current pulse.

28. The method of claim 16, in which the delivering electrical energy includes delivering at least one substantially direct current (DC) pulse.

29. The method of claim 16, in which the delivering electrical energy includes delivering at least one pulse having a current density between about 1 ampere/cm² and about 4 amperes/cm².

30. The method of claim 16, in which the positioning the first electrode includes contacting the first electrode with the stent.

69. The method of claim 16, in which the determining the desired energy level includes establishing the desired energy at a level that is sufficient to inhibit or reduce stenosis without impairing nearby myocardial cells.

70. The method of claim 16, in which the determining the desired energy level includes establishing the desired energy at an energy that is sufficient to affect smooth muscle cells in a medial layer of a blood vessel without impairing nearby myocardial cells.

71. The method of claim 16, in which the measuring the impedance includes delivering a test current, measuring a resulting voltage, and calculating the impedance using the test current and the measured resulting voltage.

72. The method of claim 71, in which the delivering the test current includes delivering a subthreshold alternating current.

73. The method of claim 72, in which the delivering the subthreshold alternating current includes delivering the subthreshold alternating current at a frequency between about 5 kiloHertz and about 50 kiloHertz.

74. The method of claim 71, in which the delivering the test current includes delivering a test current having an amplitude between about 10 microamperes and about 50 microamperes.

75. The method of claim 16, in which the positioning the first electrode includes positioning an electrode on a balloon portion of a catheter.

76. The method of claim 16, in which the positioning the first electrode includes positioning a coil spring electrode.

31. A method comprising:

positioning a first electrode near an implanted intravascular stent;

positioning a second electrode at a different position from the first electrode;

measuring an impedance between the first and second electrodes;

determining a desired energy level, using the measured impedance, wherein the desired energy level is appropriate for inhibiting or reducing stenosis without affecting nearby myocardial tissue;

delivering electrical energy at the desired energy level between the first and second electrodes.

32. The method of claim 31, wherein the positioning the second electrode includes positioning the second electrode at a remote position outside a lumen of the stent.

33. The method of claim 32, wherein the positioning the second electrode includes positioning the second electrode external to a patient.

34. The method of claim 33, wherein the positioning the second electrode includes positioning the second electrode on a dermal surface.

35. The method of claim 31, wherein the positioning the first electrode includes positioning the first electrode within a blood vessel.

36. The method of claim 35, wherein the positioning the first electrode includes positioning at least a portion of the first electrode within a lumen of stent.

37. The method of claim 35, wherein the positioning the first electrode includes positioning the first electrode within a lumen of the stent such that first and second electrode ends substantially align with respective first and second stent ends.

38. The method of claim 31, wherein positioning the first electrode includes positioning the first electrode on a catheter, and wherein the positioning the second electrode includes positioning the second electrode on the same catheter.

39. The method of claim 31, wherein at least one of the positioning the first electrode and the positioning the second electrode includes contacting one of the first and second electrodes with the stent.

40. The method of claim 31, further including sensing a cardiac signal, and wherein the delivering electrical energy includes delivering at least one pulse during a predetermined portion of a cardiac cycle.

41. The method of claim 31, in which the delivering electrical energy includes discharging a capacitor.

42. The method of claim 31, in which the delivering electrical energy includes delivering at least one substantially constant current pulse.

43. The method of claim 31, in which the delivering electrical energy includes delivering at least one substantially direct current (DC) pulse.

44. The method of claim 31, in which the delivering electrical energy includes delivering at least one pulse having a current density between about 1 ampere/cm² and about 4 amperes/cm².

45. The method of claim 31, in which the measuring the impedance includes:

delivering a test current between the first and second; and

measuring a resulting voltage between the first and second electrodes, the resulting voltage resulting from the delivering the test current.

46. The method of claim 31, in which the determining the desired energy level of the electrical energy includes determining a voltage amplitude of the electrical energy.

47. The method of claim 46, in which the determining the voltage amplitude of the electrical energy includes calculating the voltage amplitude using the measured impedance and a predetermined critical current density value.

48. The method of claim 47, in which the calculating the voltage amplitude includes multiplying the predetermined critical current density value by a surface area of at least one of the first and second electrodes.

49. The method of claim 31, in which the positioning the first electrode includes contacting the first electrode with the stent.

50. A method comprising:

positioning a first electrode near an implanted intravascular stent;

positioning a second electrode at a different position from the first electrode;

measuring an impedance using the first and second electrodes;

determining a desired energy level, using the measured impedance, in which the desired energy level is determined using a predetermined desired current density between the first and second electrodes; and

delivering electrical energy between the first and second electrodes at the desired energy level to inhibit or reduce stenosis.

51. The method of claim 50, wherein the positioning the second electrode includes positioning the second electrode at a remote position outside a lumen of the stent.

52. The method of claim 51, wherein the positioning the second electrode includes positioning the second electrode external to a patient.

53. The method of claim 52, wherein the positioning the second electrode includes positioning the second electrode on a dermal surface.

54. The method of claim 50, wherein the positioning the first electrode includes positioning the first electrode within a blood vessel.

55. The method of claim 54, wherein the positioning the first electrode includes positioning at least a portion of the first electrode within a lumen of stent.

56. The method of claim 54, wherein the positioning the first electrode includes positioning the first electrode within a lumen of the stent such that first and second electrode ends substantially align with respective first and second stent ends.

57. The method of claim 55, wherein positioning the first electrode includes positioning the first electrode on a catheter, and wherein the positioning the second electrode includes positioning the second electrode on the same catheter.

58. The method of claim 50, wherein at least one of the positioning the first electrode and the positioning the second electrode includes contacting one of the first and second electrodes with the stent.

59. A method comprising:

positioning a first electrode near an implanted intravascular stent;

positioning a second electrode at a different position from the first electrode; and

delivering a substantially constant DC current between the first electrode and the second electrode;

measuring an impedance using the substantially constant DC current;

determining a desired energy level, using the measured impedance, for inhibiting or reducing stenosis; and

delivering electrical energy between the first and second electrodes at the desired energy level to inhibit or reduce stenosis.

60. The method of claim 59, wherein the positioning the second electrode includes positioning the second electrode at a remote position outside a lumen of the stent.

61. The method of claim 59, wherein the positioning the second electrode includes positioning the second electrode external to a patient.

62. The method of claim 61, wherein the positioning the second electrode includes positioning the second electrode on a dermal surface.

63. The method of claim 59, wherein the positioning the first electrode includes positioning the first electrode within a blood vessel.

64. The method of claim 63, wherein the positioning the first electrode includes positioning at least a portion of the first electrode within a lumen of stent.

65. The method of claim 63, wherein the positioning the first electrode includes positioning the first electrode within a lumen of the stent such that first and second electrode ends substantially align with respective first and second stent ends.

66. The method of claim 59, wherein positioning the first electrode includes positioning the first electrode on a catheter, and wherein the positioning the second electrode includes positioning the second electrode on the same catheter.

67. The method of claim 59, wherein at least one of the positioning the first electrode and the positioning the second electrode includes contacting one of the first and second electrodes with the stent.

68. The method of claim 59, in which the positioning the first electrode includes contacting the first electrode with the stent.