BAND STOP FILTER EMPLOYING A CAPACITOR AND AN INDUCTOR TANK CIRCUIT TO ENHANCE MRI COMPATIBILITY OF ACTIVE MEDICAL DEVICES

• US 20130073021A1
• Filed: 11/18/2012
• Published: 03/21/2013
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Halperin, Henry R., Stevenson, Robert A., Kondabatni, Kishore Kumar, Frysz, Christine A.
• Granted Patent: US 9,295,828 B2
• Time in Patent Office: Days
• US Class Current: 607/116
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2090/374 NMR or MRI
• 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: G01R 33/3685 Means for reducing sheath currents, e.g. RF traps, baluns

Abstract

An implantable lead includes a lead conductor having a length extending from a proximal end to a distal end. A self-resonant inductor is connected in series along a portion of the length of the lead conductor. The self-resonant inductor includes a single length of conductive material including a dielectric coating substantially surrounding the single length of conductive material. The self-resonant inductor includes a first coiled or spiral conductor disposed along an inductor section spanning in a first direction from a first location to a second location. A second coiled or spiral conductor is disposed along the inductor section spanning in a second direction from the second location to the first location, where the second direction is opposite the first direction. A third coiled or spiral conductor is disposed along the inductor section spanning in the first direction from the first location to the second location.

Claims

1. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

an insulated and self-resonant inductive coil connected in series along a portion of length of the lead conductor, wherein the inductive coil comprises a parasitic capacitance between its adjacent turns such that the inductive coil becomes self-resonant at a selected center frequency or across a range of frequencies about the selected center frequency.

2. The lead of claim 1, wherein the selected center frequency comprises an MRI RF pulsed frequency.

3. The lead of claim 2, wherein the insulated and self-resonant inductive coil comprises a tank filter performance.

4. The lead of claim 3, wherein the tank filter performance attenuates the MRI RF pulsed frequency.

5. The lead of claim 4, wherein the self-resonant inductive coil has an inductance with an associated resistance and a parasitic capacitance with an associated resistance which determines an overall Q of the tank filter performance.

6. The lead of claim 5, wherein the overall Q of the tank filter performance is on the order of megahertz.

7. The lead of claim 5, wherein a resultant 3 dB bandwidth is at least 128 kHz.

8. The lead of claim 4, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for the biological frequency range of 0-1 kHz.

9. The lead of claim 8, wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

10. The lead of claim 1, including a dielectric coating substantially surrounding the inductive coil.

11. The lead of claim 1, wherein the insulated and self-resonant inductive coil is shielded.

12. The lead of claim 11, wherein the shield comprises a conductive electromagnetic shield.

13. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

an insulated and self-resonant inductive coil connected in series along a portion of length of the lead conductor, wherein the inductive coil comprises a parasitic capacitance between its adjacent turns such that the inductive coil becomes self-resonant at an MRI RF pulsed frequency, wherein the self-resonant inductive coil has an inductance with an associated resistance and a parasitic capacitance with an associated resistance which determines an overall Q of the tank filter performance where a resultant 3 dB bandwidth is at least 128 kHz.

14. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, the self-resonant inductor comprising a single length of conductive material comprising a dielectric coating substantially surrounding the single length of conductive material, wherein the self-resonant inductor comprises;

a first insulated coiled or spiral conductor disposed along an inductor section spanning in a first direction from a first location to a second location;

a second insulated coiled or spiral conductor disposed along the inductor section spanning in a second direction from the second location to the first location, wherein the second direction is opposite the first direction; and

a third insulated coiled or spiral conductor disposed along the inductor section spanning in the first direction from the first location to the second location.

15. The lead of claim 14, wherein the first coiled or spiral conductor is disposed within the second coiled or spiral conductor, and wherein the second coiled or spiral conductor is disposed within the third coiled or spiral conductor.

16. The lead of claim 14, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns wherein the inductor becomes self-resonant at a selected center frequency or across a range of frequencies about the selected center frequency.

17. The lead of claim 16, wherein the selected center frequency comprises an MRI RF pulsed frequency.

18. The lead of claim 17, wherein the self-resonant inductor comprises a tank filter performance.

19. The lead of claim 18, wherein the tank filter performance attenuates the MRI RF pulsed frequency.

20. The lead of claim 19, wherein the self-resonant inductor has an inductance with an associated resistance and a parasitic capacitance with an associated resistance which determines an overall Q of the tank filter performance.

21. The lead of claim 20, wherein the overall Q of the tank filter performance is on the order of megahertz.

22. The lead of claim 20, wherein a resultant 3 dB bandwidth is at least 128 kHz.

23. The lead of claim 19, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz.

24. The lead of claim 23, wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

25. The lead of claim 14, wherein the self-resonant inductor is shielded.

26. The lead of claim 25, wherein the self-resonant inductor comprises a parasitic capacitance between any of the first, second or third coiled or spiral conductors and the shield.

27. The lead of claim 26, wherein the self-resonant inductor comprises an inductance in parallel with a capacitance, a first resonant center frequency removed from the shield and a second resonant center frequency within the shield, wherein the inductance or the capacitance is adjusted to account for a shift between the first and second resonant frequencies.

28. The lead of claim 27, wherein the self-resonant inductor comprises an overall circuit Q within the shield wherein the resultant 3 dB bandwidth is at least 128 kHz, such that the self-resonant inductor attenuates an RF current flow substantially about the second resonant center frequency.

29. The lead of claim 28, wherein the shield comprises a conductive electromagnetic shield.

30. The lead of claim 14, wherein the single length of conductive material comprises a cored, clad, plated, electroplated, anodized or filled tube construction.

31. The lead of claim 14, wherein the single length of conductive material comprises an inner conductive core substantially surrounded by an outer conductive layer.

32. The lead of claim 31, wherein the outer conductive layer is biocompatible.

33. The lead of claim 31, wherein the outer conductive layer comprises MP35N, nitinol, tungston, tantalum, niobium, Co—

Cr—

Mo alloys, stainless steel alloys, stainless steel alloys with Mo, Ni, Cr combinations, carbon steels, or any combination thereof.

34. The lead of claim 31, wherein the inner conductive core comprises silver, copper, platinum, platinum, platinum-iridium, platinum-tungsten, platinum alloys, tantalum, gold, palladium, nitinol, titanium or titanium alloys.

35. The lead of claim 14, wherein the dielectric coating comprises a thermoset, thermoplastic or flexible coating.

36. The lead of claim 35, wherein the thermoset dielectric coating comprises a resin or modifier comprising pigments, plasticizers, filler particulates, flakes, spheres, nanoparticles, short fibers, long fibers, submicron fibers, isotropically dispersed submicron fibers, anistropically dispersed submicron fibers, laminate configurations or any combination thereof.

37. The lead of claim 35, wherein the dielectric coating comprises adhesives, elastomers, epoxies, fluoropolymers, copolymer blends, amorphous copolymer blends, semi-amorphous copolymer blends, copolymer blends with limited crosslinking or any combination thereof.

38. The lead of claim 35, wherein the dielectric coating comprises acrylonitrile butadiene styrene (ABS), acrylics, poly(methyl methacrylate) or PMMA, celluloids, acetates, cellulose acetate, ethylene-vinyl acetate, copolymers, cyclic olefin copolymer, polyethylene, poly(vinyl chloride), polystyrene, acetals, urethanes, carbothane, estane, pellethane, Tecoflex, Tecothane, Texin, nylons, Aesno, Besno, Nylon 6, Nylon 6,6, Nylon 12, Pebax, Vestamid, polyether, polyester, polypropylene, polytetrafluoroethylene (PTFE), FEP, PFA, CTFE, ECTFE, PEEK, ETFE, PET, PBT, polyvinylidine fluoride (PVDF), ETTFE, THV, polycarbonate, polyetherimide, polysulfone, parylene, polyethelene, polypropylene, polyether block amids (PEBAX), acid copolymers, or any combination thereof.

39. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, wherein the self-resonant inductor comprises;

a first coiled or spiral conductor disposed along an inductor section spanning in a first direction from a first location to a second location;

a second coiled or spiral conductor disposed along the inductor section spanning in a second direction from the second location to the first location, wherein the second direction is opposite the first direction; and

a third coiled or spiral conductor disposed along the inductor section spanning in the first direction from the first location to the second location.

40. The lead of claim 39, wherein the first coiled or spiral conductor is electrically connected to the second coiled or spiral conductor, and wherein the second coiled or spiral conductor is electrically connected to the third coiled or spiral conductor.

41. The lead of claim 39, wherein the first coiled or spiral conductor is disposed within the second coiled or spiral conductor, and wherein the second coiled or spiral conductor is disposed within the third coiled or spiral conductor.

42. The lead of claim 39, wherein the first, second and third coiled or spiral conductors comprise a dielectric coating substantially surrounding the conductors.

43. The lead of claim 39, wherein the first, second and third coiled or spiral conductors comprise a continuous single length of conductive material.

44. The lead of claim 39, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns between the first and second coiled or spiral conductors and the second and third coiled or spiral conductors wherein the inductor becomes self-resonant at a selected center frequency or across a range of frequencies about the selected center frequency, wherein the selected center frequency comprises an MRI RF pulsed frequency.

45. The lead of claim 39, wherein the self-resonant inductor comprises a tank filter performance attenuating the MRI RF pulsed frequency.

46. The lead of claim 45, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz, and wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

47. The lead of claim 45, wherein a resultant 3 dB bandwidth is at least 128 kHz.

48. The lead of claim 39, wherein the self-resonant inductor is shielded.

49. The lead of claim 48, wherein the shield comprises a conductive electromagnetic shield.

50. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, the self-resonant inductor comprising a single length of conductive material including a dielectric coating substantially surrounding the single length of conductive material, wherein the self-resonant inductor comprises;

a first coiled or spiral conductor disposed along an inductor section spanning in a first direction from a first location to a second location;

a second coiled or spiral conductor disposed along the inductor section spanning in a second direction from the second location to the first location, where the second direction is opposite the first direction; and

a third conductor disposed along the inductor section spanning in the first direction from the first location to the second location.

51. The lead of claim 50, wherein the third conductor is disposed inside or outside both the first and second coiled or spiral conductors.

52. The lead of claim 51, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns wherein the inductor becomes self-resonant at a selected center frequency or across a range of frequencies about the selected center frequency.

53. The lead of claim 52, wherein the selected center frequency comprises an MRI RF pulsed frequency and the self-resonant inductor comprises a tank filter performance attenuating the MRI RF pulsed frequency.

54. The lead of claim 53, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz, and wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

55. The lead of claim 53, wherein a resultant 3 dB bandwidth is at least 128 kHz.

56. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, the self-resonant inductor comprising a single length of conductive material including a dielectric coating substantially surrounding the single length of conductive material, wherein the self-resonant inductor comprises;

a first coiled or spiral conductor disposed along an inductor section spanning in a first direction from a first location to a second location;

a second conductor disposed along the inductor section in a second direction opposite the first direction spanning from the second location to the first location; and

a third coiled or spiral conductor disposed along the inductor section spanning in the first direction from the first location to the second location.

57. The lead of claim 56, wherein the first coiled or spiral conductor is disposed inside the third coiled or spiral conductor, and wherein the second conductor is disposed between the first and second coiled or spiral conductors.

58. The lead of claim 57, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns wherein the inductor becomes self-resonant at a selected center frequency or across a range of frequencies about the selected center frequency.

59. The lead of claim 58, wherein the selected center frequency comprises an MRI RF pulsed frequency and the self-resonant inductor comprises a tank filter performance attenuating the MRI RF pulsed frequency.

60. The lead of claim 59, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz, and wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

61. The lead of claim 59, wherein a resultant 3 dB bandwidth is at least 128 kHz.

62. An RF/MRI compatible medical device comprising:

an elongate electrical medical lead comprising at least one conductor with opposing proximal and distal portions, the at least one conductor having a first section that extends in a first lengthwise direction for a first physical length, then turns to define at least one reverse section that extends in a substantially opposing lengthwise direction for a second physical length, then turns again to define a third section that extends in the first lengthwise direction for a third physical length.

63. The medical device of claim 62, wherein at least one of the sections have a coiled portion.

64. The medical device of claim 62, wherein at least two of the sections have a coiled portion.

65. The medical device of claim 64, wherein at least one of the first, reverse or third sections extends under, over or through a neighboring section.

66. The medical device of claim 64, wherein at least one of the sections resides proximate to and outside of a coiled portion of another section.

67. The medical device of claim 64, wherein the first, reverse and third sections comprise a continuous single length of conductive material.

68. The medical device of claim 67, wherein the continuous single length of conductive material comprises a cored, clad, plated, electroplated, anodized or filled tube construction.

69. The medical device of claim 67, wherein the single length of conductive material comprises an inner conductive core substantially surrounded by an outer conductive layer, wherein the outer conductive layer is biocompatible.

70. The medical device of claim 69, wherein the outer conductive layer comprises MP35N, nitinol, tungston, tantalum, niobium, Co—

Cr—

Mo alloys, stainless steel alloys, stainless steel alloys with Mo, Ni, Cr combinations, carbon steels, or any combination thereof.

71. The medical device of claim 70, wherein the inner conductive core comprises silver, copper, platinum, platinum, platinum-iridium, platinum-tungsten, platinum alloys, tantalum, gold, palladium, nitinol, titanium or titanium alloys.

72. The medical device of claim 62, wherein the first, reverse and third sections comprise a dielectric coating, wherein the dielectric coating comprises a thermoset, thermoplastic or flexible coating.

73. The medical device of claim 72, wherein the thermoset dielectric coating comprises a resin or modifier comprising pigments, plasticizers, filler particulates, flakes, spheres, nanoparticles, short fibers, long fibers, submicron fibers, isotropically dispersed submicron fibers, anistropically dispersed submicron fibers, laminate configurations or any combination thereof.

74. The medical device of claim 72, wherein the dielectric coating comprises adhesives, elastomers, epoxies, fluoropolymers, copolymer blends, amorphous copolymer blends, semi-amorphous copolymer blends, copolymer blends with limited crosslinking or any combination thereof.

75. The medical device of claim 72, wherein the dielectric coating comprises acrylonitrile butadiene styrene (ABS), acrylics, poly(methyl methacrylate) or PMMA, celluloids, acetates, cellulose acetate, ethylene-vinyl acetate, copolymers, cyclic olefin copolymer, polyethylene, poly(vinyl chloride), polystyrene, acetals, urethanes, carbothane, estane, pellethane, Tecoflex, Tecothane, Texin, nylons, Aesno, Besno, Nylon 6, Nylon 6,6, Nylon 12, Pebax, Vestamid, polyether, polyester, polypropylene, polytetrafluoroethylene (PTFE), FEP, PFA, CTFE, ECTFE, PEEK, ETFE, PET, PBT, polyvinylidine fluoride (PVDF), ETTFE, THV, polycarbonate, polyetherimide, polysulfone, parylene, polyethelene, polypropylene, polyether block amids (PEBAX), acid copolymers, or any combination thereof.

76. The medical device of claim 64, wherein the at least one conductor including the first, reverse and third sections are shielded.

77. The medical device of claim 76, wherein the at least one conductor comprises a parasitic capacitance between any of the first, reverse or third sections and the shield.

78. The medical device of claim 77, wherein the at least one conductor comprises an inductance in parallel with a capacitance, a first resonant center frequency removed from the shield and a second resonant center frequency within the shield, wherein the inductance or the capacitance is adjusted to account for a shift between the first and second resonant frequencies.

79. The medical device of claim 78, wherein the at least one conductor comprises an overall circuit Q within the shield wherein the resultant 3 dB bandwidth is at least 128 kHz, such that the at least one conductor attenuates an RF current flow substantially about the second resonant center frequency.

80. The medical device of claim 76, wherein the shield comprises a conductive electromagnetic shield.

81. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, the self-resonant inductor comprising a single length of conductive material comprising a dielectric coating substantially surrounding the single length of conductive material, wherein the self-resonant inductor comprises;

an n number of layers of insulated coiled or spiral conductors disposed along an inductor section spanning back and forth between a first location and a second location, wherein the n number of layers comprises two or more even number of insulated coiled or spiral conductors; and

a return conductor electrically connected to the n number of layers of coiled or spiral conductors.

82. The lead of claim 81, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns wherein the inductor becomes self-resonant at an MRI RF pulsed frequency.

83. The lead of claim 82, wherein the self-resonant inductor comprises a tank filter performance attenuating the MRI RF pulsed frequency.

84. The lead of claim 83, wherein the self-resonant inductor has an inductance with an associated resistance and a parasitic capacitance with an associated resistance which determines an overall Q of the tank filter performance.

85. The lead of claim 84, wherein the overall Q of the tank filter performance is on the order of megahertz.

86. The lead of claim 84, wherein a resultant 3 dB bandwidth is at least 128 kHz.

87. The lead of claim 84, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz.

88. The lead of claim 84, wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

89. The lead of claim 84, wherein the self-resonant inductor comprises an electromagnetic shield, wherein the self-resonant inductor comprises a parasitic capacitance between any of the n number of layers of coiled or spiral conductors and the shield, and wherein the self-resonant inductor comprises an inductance in parallel with a capacitance, a first resonant center frequency removed from the shield and a second resonant center frequency within the shield, wherein the inductance or the capacitance is adjusted to account for a shift between the first and second resonant frequencies, wherein the self-resonant inductor attenuates the MRI RF pulsed frequency substantially about the second resonant center frequency.

90. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a lead conductor having a length extending from a proximal end to a distal end; and

a self-resonant inductor connected in series along a portion of the length of the lead conductor, the self-resonant inductor comprising a single length of conductive material comprising a dielectric coating substantially surrounding the single length of conductive material, wherein the self-resonant inductor comprises;

an n number of layers of insulated coiled or spiral conductors disposed along an inductor section spanning back and forth between a first location and a second location, wherein the n number of layers comprises three or more odd number of layers of insulated coiled or spiral conductors.

91. The lead of claim 90, wherein the self-resonant inductor comprises a parasitic capacitance between its adjacent turns wherein the inductor becomes self-resonant at an MRI RF pulsed frequency.

92. The lead of claim 91, wherein the self-resonant inductor comprises a tank filter performance attenuating the MRI RF pulsed frequency.

93. The lead of claim 92, wherein the self-resonant inductor has an inductance with an associated resistance and a parasitic capacitance with an associated resistance which determines an overall Q of the tank filter performance.

94. The lead of claim 93, wherein the overall Q of the tank filter performance is on the order of megahertz.

95. The lead of claim 93, wherein a resultant 3 dB bandwidth is at least 128 kHz.

96. The lead of claim 93, wherein the tank filter performance comprises less than or equal to 3 dB of attenuation for a biological frequency range of 0-1 kHz.

97. The lead of claim 93, wherein the tank filter performance comprises greater than or equal to 15 dB of attenuation at or near the MRI RF pulsed frequency.

98. The lead of claim 93, wherein the self-resonant inductor comprises an electromagnetic shield, wherein the self-resonant inductor comprises a parasitic capacitance between any of the n number of layers of coiled or spiral conductors and the shield, and wherein the self-resonant inductor comprises an inductance in parallel with a capacitance, a first resonant center frequency removed from the shield and a second resonant center frequency within the shield, wherein the inductance or the capacitance is adjusted to account for a shift between the first and second resonant frequencies, wherein the self-resonant inductor attenuates the MRI RF pulsed frequency substantially about the second resonant center frequency.