TUNED ENERGY BALANCED SYSTEM FOR MINIMIZING HEATING AND/OR TO PROVIDE EMI PROTECTION OF IMPLANTED LEADS IN A HIGH POWER ELECTROMAGNETIC FIELD ENVIRONMENT

• US 20100160997A1
• Filed: 01/12/2010
• Published: 06/24/2010
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Dabney, Warren S., Stevenson, Robert A., Lardo, Albert C., Moschiano, Holly Noelle, Brainard, Scott, Johnson, Robert Shawn, Halperin, Henry R., Kaiser, Daniel Robert, Williams, Christopher Michael
• Granted Patent: US 8,989,870 B2
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• 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 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR

Abstract

An energy management system facilitates the transfer of high frequency energy coupled into an implanted lead at a selected RF frequency or frequency band, to an energy dissipating surface. This is accomplished by conductively coupling the implanted lead to the energy dissipating surface through an energy diversion circuit including one or more passive electronic network components whose impedance characteristics are at least partially tuned to the implanted lead'"'"'s impedance characteristics.

Claims

1. A tuned energy balanced system for minimizing heating of an implanted lead and/or providing EMI protection in a high power electromagnetic field environment, comprising:

an implanted lead having impedance characteristics at a selected RF frequency or frequency band;

an energy dissipating surface associated with the implanted lead; and

an energy diversion circuit conductively coupling the implanted lead to the energy dissipating surface, the energy diversion circuit comprising one or more passive electronic network components whose impedance characteristics are at least partially tuned to the implanted lead'"'"'s impedance characteristics, to facilitate transfer to the energy dissipating surface of high frequency energy induced on the implanted lead at the selected RF frequency or frequency band.

2. The system of claim 1, wherein the selected RF frequency or frequency band comprises an MRI frequency.

3. The system of claim 2, wherein said MRI frequency comprises a range of MRI frequencies.

4. The system of claim 1, wherein the energy diversion circuit has a reactance and is vectorially opposite to the characteristic reactance of the implanted lead.

5. The system of claim 4, wherein the energy diversion circuit has a capacitive reactance generally equal and opposite to the characteristic inductive reactance of the implanted lead.

6. The system of claim 1, wherein the capacitive reactance and the inductive reactance each have a resistor component.

7. The system of claim 1 or 6, wherein the energy diversion circuit comprises a low pass filter.

9. The system of claim 1 or 6, wherein the energy diversion circuit comprises at least one series resonant LC trap filter.

10. The system of claim 9, wherein the energy diversion circuit comprises a plurality of LC trap filters resonant respectively at different MRI frequencies.

11. The system of claim 1, wherein the energy dissipating surface comprises a housing for an active implantable medical device (AIMD).

12. The system of claim 11, wherein the AIMD comprises an implantable hearing device, a neurostimulator, a brain stimulator, a cardiac pacemaker, a left ventricular assist device, an artificial heart, a drug pump, a bone growth stimulator, a urinary incontinence device, a spinal cord stimulator, an anti-tremor stimulator, an implantable cardioverter defibrillator, a congestive heart failure device, or a cardio resynchronization therapy device.

13. The system of claim 1, wherein the implanted lead has a length extending between and to a proximal end and a tissue-stimulating or biological-sensing electrode at or near a distal tip end.

14. The system of claim 13, wherein the energy dissipating surface is disposed at a point or an area spaced from the electrode.

15. The system of claim 14, wherein the energy dissipating surface is disposed within the blood flow of a patient.

16. The system of claim 14, wherein the energy dissipating surface comprises a ring electrode.

17. The system of claim 13, further comprising a lead housing supporting said leadwire distal tip electrode at one end thereof, said lead housing including a conductive housing portion forming the energy dissipating surface, and an insulator housing portion between said distal tip electrode and said conductive housing portion.

18. The system of claim 1, including an impeding circuit associated with the energy diversion circuit, for raising the high-frequency impedance of the implanted lead.

19. The system of claim 18, wherein the impeding circuit comprises an inductor.

20. The system of claim 18, wherein the impeding circuit comprises a bandstop filter.

21. The system of claim 19 or 20, wherein the energy diversion circuit comprises a resistor.

22. The system of claim 19 or 20, wherein the wherein the energy diversion circuit comprises a low pass filter.

23. The system of claim 22, wherein the low pass filter comprises a capacitor, an inductor, a Pi filter, a T filter, an LL filter, or an “

n”

element filter.

24. The system of claim 19 or 20, wherein the energy diversion circuit comprises at least one series resonant LC trap filter.

25. The system of claim 24, wherein the energy diversion circuit comprises a plurality of LC trap filters resonant respectively at different MRI frequencies.

26. The system of claim 22, wherein the energy diversion circuit comprises a resistor.

27. The system of claim 24, wherein the energy diversion circuit comprises a resistor.

29. The system of claim 1, wherein the energy dissipating surface comprises convolutions or fins, for increasing the surface area thereof.

30. The system of claim 1, wherein the energy dissipating surface includes a roughened surface.

31. The system of claim 30, wherein the roughened surface is formed through plasma or chemical etching, porous or fractal coatings or surfaces, whiskers, morphologically designed columbar structures, vapor, electron beam or sputter deposition of a high surface area energy conductive material, or carbon nanotubes.

32. The system of claim 1, wherein the implanted lead comprises at least a portion of a probe or a catheter.

33. The system of claim 32, wherein the energy dissipating surface is selected from the group consisting essentially of a sheath, an insulative body, or a thermally conductive element.

34. The system of claim 1, wherein the implanted lead comprises at least a pair of leads each having a length extending between and to a proximal end and a tissue-stimulating or biological-sensing electrode at a distal tip end.

35. The system of claim 34, wherein said energy diversion circuit couples each of said leads to the energy dissipating surface which is disposed at a point or an area distant from each of said electrodes.

36. The system of claim 34 or 35, wherein said energy diversion circuit is coupled between said pair of leads.

37. The system of claim 11, wherein said energy diversion circuit is mounted within said housing.

38. The system of claim 37, wherein said housing is hermetically sealed.

39. The system of claim 37, wherein said active implantable medical device (AIMD) comprises a deep brain stimulator.

40. The system of claim 39, wherein said housing is adapted for mounting in thermal communication with a patient'"'"'s skull.

41. The system of claim 39, further comprising an electrode shaft assembly having a proximal end carried by said housing, said at least one lead extending through said electrode shaft assembly and having said distal tip end electrode for contacting patient brain tissue.

42. The system of claim 17, wherein said distal tip electrode cooperates with said conductive and insulator housing portions to define a hermetically sealed package having said energy diversion circuit mounted therein.

43. The system of claim 42, wherein said hermetically sealed package has a generally tubular shape with said distal tip electrode mounted at one end thereof, and further defining a hermetic seal assembly at an opposite end thereof, said lead extending through said hermetic seal assembly.

44. The system of claim 42, further comprising an impeding circuit associated with said energy diversion circuit and mounted within said hermetically sealed package.

45. The system of claim 44, wherein said impeding circuit comprises at least one inductor.

46. The system of claim 45, wherein said at least one inductor comprises an inductor chip.

47. The system of claim 45, wherein said at least one inductor comprises an inductor wire wound onto a ferromagnetic or non-ferromagnetic mandrel.

48. The system of claim 42, wherein said energy diversion circuit comprises at least one capacitor coupled between said leadwire and said energy dissipating surface.

49. The system of claim 45, wherein said at least one inductor comprises two inductor elements disposed in series, said energy diversion circuit being coupled between said pair of inductor elements and said energy dissipating surface.

50. The system of claim 49, wherein said energy diversion circuit comprises at least one capacitor.

51. The system of claim 42, wherein said energy diversion circuit comprises at least one LC trap filter coupled between said lead and said energy dissipating surface.

52. The system of claim 51, wherein said at least one LC trap filter comprises a plurality of LC trap filters resonant respectively at different MRI frequencies.

53. The system of claim 1, further comprising means for hermetically sealed mounting of said energy dissipating surface along said lead between proximal and distal ends thereof, said hermetically sealed means defining a chamber having said energy diversion circuit mounted therein.

54. The system of claim 53, wherein said lead comprises a first lead having a tip electrode at a distal end thereof, and a second lead having a ring electrode at a distal end thereof, said first and second leads having said energy dissipating surface disposed in hermetically sealed relation therewith and extending through said chamber, said energy diversion circuit coupling said first and second leads to said energy dissipating surface.

55. The system of claim 54, wherein said energy diversion circuit comprises a unipolar or multipolar feedthrough capacitor.

56. The system of claim 53, further comprising an impeding circuit associated with said energy diversion circuit and mounted within said hermetically sealed chamber.

57. The system of claim 13, wherein the energy dissipating surface comprises a probe or a catheter.

58. The system of claim 57, wherein said electrode comprises an ablation tip electrode.

59. The system of claim 58, further comprising a probe housing having said ablation tip electrode at or near a distal end thereof, wherein said energy dissipating surface is disposed at a point or an area distant from said ablation tip electrode, said energy diversion circuit diverting high frequency energy away from said ablation tip electrode to said energy dissipating surface.

60. The system of claim 59, wherein said implanted lead comprises a first lead having said ablation tip electrode at or near a distal end thereof, at least one second lead having a ring electrode at or near a distal end thereof, said energy diversion circuit diverting high frequency energy away from said ablation tip and said ring electrode to said energy dissipating surface.

61. The system of claim 1, wherein the energy dissipating surface comprises at least a portion of a handle for a probe or catheter.

62. The system of claim 1, wherein the energy dissipating surface is disposed within an insulative sheath.

63. The system of claim 1, wherein the energy dissipating surface comprises a plurality of spaced-apart energy dissipating surfaces.

64. The system of claim 13, including a tether disposed between and conductively coupling the electrode and the energy dissipating surface.

65. The system of claim 13, wherein the electrode comprises a paddle electrode disposed on one side of a paddle.

66. The system of claim 65, wherein the energy dissipating surface is disposed on a second side of the paddle.

67. The system of claim 66, wherein the energy diversion circuit comprises a capacitive element disposed within the paddle between the electrode and the energy dissipating surface.

68. The system of claim 67, wherein the capacitive element comprises a discrete capacitor.

69. The system of claim 67, wherein the capacitive element comprises parasitic capacitance.

70. The system of claim 65, wherein the energy dissipating surface is attached to the paddle.

71. The system of claim 1, wherein the energy dissipating surface comprises a material capable of being visualized during a magnetic resonance scan.

72. The system of claim 11, wherein the energy diversion circuit comprises a short to the housing.

73. The system of claim 1, wherein the energy dissipating surface includes a biomimetic coating.

74. The system of claim 1, wherein the energy diversion circuit includes at least one non-linear circuit element.

75. The system of claim 74, wherein the at least one non-linear circuit element comprises a transient voltage suppressor.

76. The system of claim 74, wherein the at least one non-linear circuit element comprises a diode or a pin diode.

77. The system of claim 1, including a switch associated with the implanted lead, for electrically opening the implanted lead without substantial degradation of the transfer to the energy dissipating surface of the high frequency energy induced on the implanted lead at the selected RF frequency or frequency band.

78. The system of claim 1 or 6, wherein the energy diversion circuit comprises a high pass filter.

79. The system of claim 78, wherein the high pass filter prevents low frequency gradient field-induced energy in the implanted lead or the leadwire from passing through the diversion circuit to the energy dissipating surface.

80. The system of claim 78, wherein the high pass filter comprises a capacitor.

81. The system of claim 80, wherein the high pass filter comprises a resistor in series with a capacitor.

82. The system of claim 78, wherein the high pass filter comprises an LC trap filter.

83. The system of claim 1, 6 or 8, wherein the energy diversion circuit is associated with a housing for an active implantable medical device (AIMD).

84. The system of claim 83, wherein the energy diversion circuit is disposed within a housing for the AIMD.

85. The system of claim 83, wherein the energy diversion circuit is disposed within a header block for the AIMD.

86. The system of claim 13, wherein the energy diversion circuit is disposed at or adjacent to the proximal end of the implanted lead.

87. The system of claim 86, wherein the energy diversion circuit is disposed in a proximal lead connector.

8. The system of claim 8, wherein the low pass filter comprises a capacitor, an inductor, a Pi filter, a T filter, an LL filter, or an “

n”

element filter.

28. The system of claim 8, wherein said energy diversion circuit comprises a unipolar or multipolar feedthrough capacitor.