MRI-safe implantable lead

• US 20050222657A1
• Filed: 11/18/2004
• Published: 10/06/2005
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Olsen, James M., Bolea, Stephen L., Wahlstrand, Carl D., Hrdlicka, Gregory A., Hoegh, Thomas Barry, Cross, Thomas E. Jr.
• Granted Patent: US 7,844,344 B2
• Time in Patent Office: Days
• US Class Current: 607/116
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/0553 Paddle shaped electrodes, e.g. for laminotomy
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads

Abstract

A stimulation lead is configured to be implanted into a patient'"'"'s body and includes at least one distal stimulation electrode and at least one conductive filer electrically coupled to the distal stimulation electrode. A jacket is provided for housing the conductive filer and providing a path distributed along at least a portion of the length of the lead for conducting induced RF energy from the filer to the patient'"'"'s body.

Claims

1. A medical lead configured to be implanted into a patient'"'"'s body and having at least one distal stimulation electrode, the lead comprising:

at least one conductive filer electrically coupled to the distal stimulation electrode; and

a jacket for housing said conductive filer and providing a path distributed along at least a portion of the length of the lead through said jacket for guiding induced RF energy from said filer to the patient'"'"'s body.

2. A medical lead according to claim 1 wherein said path comprises at least one or both of a DC current path and an AC current path between said filer and the patient'"'"'s body.

3. A medical lead according to claim 2 wherein said path comprises an AC current path.

4. A medical lead according to claim 2 wherein said path comprises a DC current path.

5. A medical lead according to claim 3 wherein said path further comprises a DC current path in series with said AC current path.

6. A medical lead according to claim 3 wherein said path further comprises a DC current path in parallel with said AC current path.

7. A medical lead according to claim 3 wherein the induced RF energy is conducted to the patient'"'"'s body at MRI frequencies.

8. A medical lead according to claim 7 wherein the MRI frequencies are in the range of 43 MHz to 215 MHz.

9. A medical lead according to claim 2 wherein said jacket includes a doping material.

10. A medical lead according to claim 9 wherein said doping material is a dielectric having a dielectric constant greater than approximately five.

11. A medical lead according to claim 9 wherein said doping material is carbon.

12. A medical lead according to claim 11 wherein the carbon is vitreous.

13. A medical lead according to claim 11 wherein the carbon is pyrolitic.

14. A medical lead according to claim 9 wherein said dielectric material is a mineral.

15. A medical lead according to claim 14 wherein said dielectric material includes at least one of calcium carbonate, titanium dioxide, aluminum dioxide, sapphire, mica, and silica.

16. A medical lead according to claim 9 wherein said dielectric material is talc.

17. A medical lead according to claim 9 wherein said doping material is a conductor.

18. A medical lead according to claim 17 wherein said conductor includes at least one of titanium, platinum, stainless steel, a chromium-cobalt alloy, and a conductive polymer.

19. A medical lead according to claim 9 wherein said jacket is substantially uniformly doped along its length.

20. A medical lead according to claim 9 wherein said jacket is doped at selective locations along its length.

21. A medical lead according to claim 9 wherein said jacket is doped non-uniformly.

22. A medical lead according to claim 20 wherein said jacket is doped proximate the stimulation electrode.

23. A medical lead according to claim 9 wherein said jacket is doped at selected circumferential regions.

24. A medical lead according to claim 1 wherein said jacket is porous.

25. A medical lead according to claim 24 wherein said jacket contains pores substantially uniformly distributed along the length of the jacket.

26. A medical lead according to claim 24 wherein said jacket is porous at selected locations along the length of the jacket.

27. A medical lead according to claim 26 wherein said jacket is porous proximate the stimulation electrode.

28. A medical lead according to claim 24 wherein said jacket is porous at selected circumferential regions.

29. A medical lead according to claim 2 wherein said jacket comprises a helical coil along at least a portion of the length of said jacket and in capacitor forming relationship with said filer.

30. A medical lead according to claim 29 wherein said coil is imbedded in said jacket.

31. A medical lead according to claim 30 wherein said jacket is provided with a plurality of pores extending from an outer surface of said jacket toward said coil.

32. A medical lead according to claim 29 wherein said coil resides around an outer surface of said jacket.

33. A medical lead according to claim 29 wherein said coil resides around and inner surface of said jacket.

34. A medical lead according to claim 29 wherein the coil is in the form of a coiled flat ribbon.

35. A medical lead according to claim 2 further comprising an insulative sheath around said filer to form an insulated filer and wherein a space exists between said insulated filer and said jacket, said space being filled with a material.

36. A medical lead according to claim 35 wherein said material is a conductive material.

37. A medical lead according to claim 36 wherein said conductive material comprises saline.

38. A medical lead according to claim 36 wherein said conductive material comprises a conductive gel.

39. A medical lead according to claim 36 wherein said conductive material comprises conductive micropheres.

40. A medical lead according to claim 35 wherein said material is a dielectric having a dielectric constant greater than approximately three.

41. A medical lead according to claim 2 wherein said filer is provided with an insulative sheath to form an insulated filer and wherein said jacket extends over only selected portions of said insulated filer.

42. A medical lead according to claim 2 wherein said at least one conductive filer comprises a plurality of insulated conductive filers, each coupled to one of a plurality of stimulation electrodes.

43. A medical lead according to claim 42 wherein said plurality of insulated conductive filers are positioned proximate an inner surface of said jacket.

44. A medical lead according to claim 2 wherein said stimulation lead further comprises a stylet lumen.

45. A medical lead according to claim 2 wherein said conductive filer is contained within an insulative sheath and wherein said jacket is comprised of a conductive material.

46. A medical lead according to claim 2 wherein said jacket is comprised of alternate sections of conductive and dielectric material.

47. A medical lead according to claim 2 wherein said jacket is comprised of alternating layers of conductive and dielectric materials.

48. A medical lead according to claim 47 wherein an outer layer of said jacket is conductive.

49. A medical lead according to claim 2 wherein said jacket is wrapped with alternating strips of conductive and insulative materials.

50. A medical lead according to claim 49 wherein said alternating strips have abutting edges.

51. A medical lead according to claim 49 wherein said alternating strips are overlapping.

52. A medical lead according to claim 51 wherein said plurality of insulated conductive filers are positioned proximate an inner surface of said jacket.

53. A medical lead according to claim 2 wherein said jacket comprises a plurality of alternating layers of conductive material and non-conductive material.

54. A medical lead according to claim 53 wherein selected ones of said plurality of alternating layers are wrapped and others are extruded.

55. A medical lead according to claim 53 wherein said jacket comprises first and second conductive wrapped layers and an intermediate non-conductive extruded layer.

56. A medical lead according to claim 2 further comprising at least one conductive strip disposed longitudinally along said lead.

57. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes, the lead comprising:

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes; and

a jacket doped with a dielectric material for housing said insulated conductive filers and providing an AC current path distributed along at least a portion of the length of the lead and through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at high frequencies.

58. A medical lead according to claim 57 wherein said high frequencies correspond to MRI frequencies.

59. A medical lead according to claim 57 wherein said high frequencies are in the range of 43 MHz to 215 MHz.

60. A medical lead according to claim 57 wherein said jacket is doped at selected circumferential regions.

61. A medical lead according to claim 57 wherein said jacket is substantially uniformly doped along its length.

62. A medical lead according to claim 57 wherein said jacket is doped at selected locations along its length.

63. A medical lead according to claim 62 wherein said jacket is doped proximate the stimulation electrodes.

64. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes;

the lead comprising;

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes; and

a jacket doped with a conductive material for housing said insulated conductive filers and providing a DC current path distributed along at least a portion of the length of the lead and through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at high frequencies.

65. A medical lead according to claim 64 wherein said DC current path has a resistance at least ten times greater than the resistance in each of said filers.

66. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes;

the lead comprising;

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes; and

a porous jacket for housing said insulated conductive filers and providing a conductive path distributed along at least a portion of the length of the lead and through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at high frequencies.

67. A medical lead according to claim 66 wherein said high frequencies correspond to MRI frequencies.

68. A medical lead according to claim 66 wherein said high frequencies are in the range of 43 MHz to 215 MHz.

69. A medical lead according to claim 67 wherein said jacket contains pores substantially uniformly distributed along the length of the jacket.

70. A medical lead according to claim 67 wherein said jacket is porous at selected locations along the length of the jacket.

71. A medical lead according to claim 67 wherein said jacket is porous proximate the stimulation electrodes.

72. A medical lead according to claim 67 wherein said jacket is porous at selected circumferential regions.

73. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes;

the lead comprising;

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes;

a jacket for housing said insulated conductive filers and providing a conductive path distributed along at least a portion of the length of the lead through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at high frequencies; and

a helical coil wound around at least a portion of the length of said jacket and in capacitor-forming relationship with each of said plurality of insulated conductive filers.

74. A medical lead according to claim 73 wherein said high frequencies correspond to MRI frequencies.

75. A medical lead according to claim 74 wherein said coil is imbedded in said jacket.

76. A medical lead according to claim 74 wherein said coil resides around an outer surface of said jacket.

77. A medical lead according to claim 74 wherein said coil resides around an inner surface of said jacket.

78. A medical lead according to claim 74 wherein the coil is in the form of a coiled flat ribbon.

79. A medical lead according to claim 78 wherein said plurality of insulated conductive filers are positioned proximate an inner surface of said jacket.

80. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes, the lead comprising:

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes; and

a jacket for housing said insulated conductive filers and providing a conductive path distributed along at least a portion of the length of the lead through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at high frequencies, the space between said insulated conductive filers and said jacket being filled with a conductive material.

81. A medical lead according to claim 80 wherein said high frequencies correspond to MRI frequencies.

82. A medical lead according to claim 81 wherein said conductive material is a saline solution.

83. A medical lead according to claim 81 wherein said conductive material is a conductive gel.

84. A medical lead configured to be implanted into a patient'"'"'s body and having a plurality of distal stimulation electrodes, the lead comprising:

a plurality of insulated conductive filers, each electrically coupled to one of the plurality of distal stimulation electrodes; and

a jacket extending over selected porous of said insulated conductive filers for providing a current path distributed along at least a portion of the length of the lead and through said jacket for conducting induced RF energy from said insulated filers to the patient'"'"'s body at MRI frequencies.

85. A pulse stimulation system configured for implantation into a patient'"'"'s body, the system comprising:

a pulse generator;

a stimulation lead having a proximal end electrically coupled to said pulse generator and having at least one distal stimulation electrode, said stimulation lead comprising;

at least one conductive filer electrically coupled to the distal stimulation electrode; and

a jacket for housing said conductive filer and providing a distributed current path along at least a portion of the length of the lead through said jacket for conducting induced RF energy from said filer to the patient'"'"'s body at high frequencies.

86. A medical lead configured to be implanted into a patient'"'"'s body and having at least one distal contact, the lead comprising:

at least one conductive filer electrically coupled to said at least one contact; and

a jacket for housing said conductive filer and providing a path distributed along the length of the lead through said jacket and for guiding induced RF energy from said filer to the patient'"'"'s body.

87. A medical lead configured to be implanted into a patient'"'"'s body, the lead comprising:

a plurality of conductive filers; and

a plurality of jackets, each jacket for insulating one of said plurality of conductive filers, the resulting plurality of jacketed filers being bundled together to form said medical lead.

88. A medical lead according to claim 87 wherein each of said jackets comprises alternating layers of conductive and non-conductive material.