SHIELDED NETWORK FOR AN ACTIVE MEDICAL DEVICE IMPLANTABLE LEAD

• US 20110054582A1
• Filed: 09/27/2010
• Published: 03/03/2011
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Lardo, Albert C., Moschiano, Holly Noelle, Halperin, Henry R., Dabney, Warren S., Stevenson, Robert A., Johnson, Robert Shawn
• Granted Patent: US 8,437,865 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 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/057 Anchoring means; Means for fixing the head inside the heart
• 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: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
• CPC Class Codes: H01F 17/00 Fixed inductances of the signal type coils in general H01F5/00; inductors without a potential-jump or surface barrier specially adapted for integrated circuits, details thereof and multistep manufacturing processes therefor H01L28/10
• CPC Class Codes: H01F 2017/065 Core mounted around conductor to absorb noise, e.g. EMI filter
• CPC Class Codes: H01F 27/363 made of electrically conductive material
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2001/0042 Wound, ring or feed-through type capacitor
• CPC Class Codes: H03H 2007/013 Notch or bandstop filters
• CPC Class Codes: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/1758 Series LC in shunt or branch path H03H7/1791 takes precedence
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence

Abstract

A shielded component or network for an active medical device (AMD) implantable lead includes (1) an implantable lead having a length extending from a proximal end to a distal end, all external of an AMD housing, (2) a passive component or network disposed somewhere along the length of the implantable lead, the passive component or network including at least one inductive component having a first inductive value, and (3) an electromagnetic shield substantially surrounding the inductive component or the passive network. The first inductive value of the inductive component is adjusted to a account for a shift in its inductance to a second inductive value when shielded.

Claims

1. A shielded component or network for an active medical device (AMD) implantable lead, comprising:

an implantable lead having a length extending from a proximal end to a distal end, all external of an AMD housing;

a passive component or network disposed somewhere along the length of the implantable lead, the passive component or network including at least one inductive component having a first inductive value; and

an electromagnetic shield substantially surrounding the inductive component or the passive network;

wherein the first inductive value of the inductive component is adjusted to account for a shift in its inductance to a second inductive value when shielded.

2. The shielded component or network of claim 1, wherein the passive component network includes at least one capacitive component electrically connected in parallel with the at least one inductive component to form a bandstop filter.

3. The shielded component or network of claim 2, wherein the inductive component comprises a solenoid inductor, a chip inductor, or a thick film inductor and wherein the capacitive component comprises a chip capacitor, parasitic capacitance, or a feedthrough capacitor.

4. The shielded component or network of claim 2, wherein the capacitive component comprises parasitic capacitance formed between coils of the inductive component and between the inductive component and the electromagnetic shield.

5. The shielded component or network of claim 4, including a dielectric material disposed between coils of the inductive component and between the inductive component and the electromagnetic shield.

6. The shielded component or network of claim 2, wherein the capacitive component and the inductive component are tuned to impede induced current flow through the implantable lead at a selected center frequency or range of frequencies.

7. The shielded component or network of claim 6, wherein the selected center frequency or range of frequencies comprises an MRI RF pulsed frequency or range of RF pulsed frequencies.

8. The shielded component or network of claim 7, wherein the MRI RF pulsed frequency range includes tens of kilohertz, hundreds of kilohertz, or megahertz.

9. The shielded component or network of any of claim 1, 2 or 6, including a non-conductive insulator or dielectric material disposed between the passive component network and the electromagnetic shield.

10. The shielded component or network of claim 2, comprising:

an inductor having first and second conductive terminals in spaced non-conductive relation; and

a capacitor having first and second conductive terminals in spaced non-conductive relation;

wherein the inductor and the capacitor are physically disposed in series relative to one another; and

wherein the inductor and the capacitor are electrically connected to one another in parallel.

11. The shielded component or network of claim 10, wherein one of the first or second conductive terminals of the inductor is disposed generally adjacent to one of the first or second conductive terminals of the capacitor.

12. The shielded component or network of claim 11, wherein the capacitor and the inductor are aligned along a common axis.

13. The shielded component or network of claim 11, wherein the adjacent conductive terminals of the inductor and the capacitor abut one another.

14. The shielded component or network of claim 11, including an electrical insulator disposed between the adjacent conductive terminals of the inductor and the capacitor.

15. The shielded component or network of claim 11 or 13, wherein electrical potential between the adjacent conductive terminals of the inductor and the capacitor is minimized.

16. The shielded component or network of claim 15, wherein the electrical potential between the adjacent conductive terminals of the inductor and the capacitor is zero.

17. The shielded component or network of claim 2 or 10, wherein the second conductive terminal of the inductor is conductively coupled to the first conductive terminal of the capacitor, and wherein the first conductive terminal of the inductor is conductively coupled to the second conductive terminal of the capacitor.

18. The shielded component or network of claim 10, comprising a plurality of paired inductor and capacitor bandstop filters, wherein each bandstop filter is physically disposed in series relative to one another.

19. The shielded component or network of claim 18, wherein each paired inductor and capacitor is electrically connected in series to another paired inductor and capacitor.

20. The shielded component or network of any of claim 2, 6 or 10, wherein the capacitive component and the inductive component comprise biocompatible and non-migratable materials.

21. The shielded component or network of claim 10, including a hermetically sealed container in which the inductor and the capacitor are disposed, wherein the hermetically sealed container forms the electromagnetic shield.

22. The shielded component or network of claim 21, wherein the hermetically sealed container comprises a biocompatible housing in which the bandstop filter is disposed, and biocompatible first and second conductive contacts extending through and in non-conductive relation with the housing, and conductively coupled in series to the bandstop filter.

23. The shielded component or network of claim 22, wherein the hermetically sealed container is disposed in series in the implantable lead.

24. The shielded component or network of claim 23, wherein the first and second contacts of the hermetically sealed container are connected to, respectively, proximal and distal portions of the lead.

25. The shielded component or network of claim 22, including a substrate onto which the inductor and the capacitor are fixed in a pre-assembly prior to insertion into the biocompatible housing.

26. The shielded component or network of claim 25, including first and second hermetic terminals comprising at least a portion of the first and second conductive contacts, respectively.

27. The shielded component or network of claim 26, wherein the hermetic terminals are hermetically sealed to the biocompatible housing after the pre-assembly is inserted therein.

28. The shielded component or network of claim 21, including an electrically insulative conformal coating over at least a portion of the hermetically sealed container.

29. The shielded component or network of any of claim 2, 6 or 10, wherein the overall Q of the bandstop filter is selected to balance impedance at the selected frequency versus frequency bandwidth characteristics.

30. The shielded component or network of claim 29, wherein the Q of the inductive component is relatively high, and the Q of the capacitive component is relatively low, and wherein the inductive component has a relatively low resistive loss, and the capacitive component has a relatively high equivalent series resistance.

31. The shielded component or network of claim 29, wherein the Q of the inductive component is relatively low, and the Q of the capacitive component is relatively high, and wherein the inductive component has a relatively high resistive loss, and wherein the capacitive component has a relatively low equivalent series resistance.

32. The shielded component or network of any of claim 1, 2, 6 or 10, wherein the active medical device (AMD) has a conductive equipotential surface, and wherein the electromagnetic shield that substantially surrounds the inductive element or the passive network is conductively coupled to either the AMD equipotential surface or to surrounding body tissue.

33. The shielded component or network of claim 32, wherein the AMD equipotential surface comprises a conductive biocompatible housing for the AMD.

34. The shielded component or network of claim 1, including an energy diversion circuit conductively coupling the implantable lead to the electromagnetic shield.

35. The shielded component or network of claim 34, wherein the energy diversion circuit comprises a low pass filter.

36. The shielded component or network of claim 35, wherein the low pass filter comprises a capacitor, an inductor, a Pi filter, a T filter, an LL filter, or an “

n”

element filter.

37. The shielded component or network of claim 34, wherein the energy diversion circuit comprises at least one series resonant L-C trap filter.

38. The shielded component or network of claim 34, wherein the energy diversion circuit comprises a high pass filter.

39. The shielded component or network of claim 35, wherein the high pass filter prevents low frequency gradient field-induced energy in the implanted lead from passing through the diversion circuit to an energy dissipating surface or ground.

40. The shielded component or network of claim 39, wherein the high pass filter comprises a capacitor, a resistor in series with a capacitor, or an L-C trap filter.

41. The shielded component or network of any of claim 1 or 34-37, including an impeding circuit for raising the high frequency impedance of the implantable lead.

42. The shielded component or network of claim 41, wherein the impeding circuit comprises an inductor.

43. The shielded component or network of claim 41, wherein the impeding circuit comprises a bandstop filter.

44. The shielded component or network of claim 34, wherein the electromagnetic shield comprises an energy dissipating surface.

45. The shielded component or network of claim 1, wherein the inductive component comprises a plurality of spaced apart inductive components disposed along the length of the implantable lead.

46. The shielded component or network of claim 45, wherein less than all of the inductive components are shielded.

47. The shielded component or network of any of claim 1, 3, 4 or 5, wherein the electromagnetic shield comprises a plurality of electromagnetic shields disposed along the length of the implantable lead.

48. The shielded component or network of claim 47, wherein an adjacent pair of the plurality of electromagnetic shields are spread apart from one another.

49. The shielded component or network of claim 47, wherein the plurality of electromagnetic shields are conductively coupled to one another.

50. The shielded component or network of claim 1, wherein the electromagnetic shield comprises a conductive heat-shrink tubing, a conductive foil, wire, braid, mesh, circuit trace, or solid tubular material, or a conductive polymer, a conductive epoxy, nano-fibers, nano-meshes, nano-coatings or nano-threads.

51. The shielded component or network of claim 1, wherein the electromagnetic shield is radially spaced from the passive component network.

52. The shielded component or network of claim 1, wherein the electromagnetic shield comprises MP35N, iridium, carbon, platinum, titanium, palladium, chromium, Wolfram, tungsten, gold, copper, or alloys thereof.

53. The shielded component or network of claim 1, wherein the inductive component comprises a chip inductor, a solenoid inductor, a Wheeler spiral, or a circuit trace inductor.

54. The shielded component or network of claim 1, wherein the implantable lead comprises a plurality of implantable leads substantially surrounded by the electromagnetic shield.

55. The shielded component or network of claim 1, wherein the AMD comprises an implantable hearing device, a cochlear implant, a piezoelectric sound bridge transducer, a neurostimulator, a brain stimulator, a cardiac pacemaker, a left ventricular assist device, an artificial heart, a drug pump, an implantable bone growth stimulator, a urinary incontinence device, a spinal cord stimulator, an anti-tremor stimulator, an implantable cardioverter defibrillator, or a congestive heart failure device.

56. The shielded component or network of claim 1, wherein empirical data is used to adjust the value of the inductance from the first inductive value to the second inductive value.

57. The shielded component or network of claim 1, including the use of an equivalent circuit model, such as PSPICE, to adjust the value of the inductance from the first inductive value to the second inductive value.

58. The shielded component or network of claim 1, including use of mathematical formulations based on a magneto-static integral equation to adjust the value of the inductance from the first inductive value to the second inductive value.

59. The shielded component or network of claim 1, including applying the ratio over the empirical inductance and divided by the inductance in the electromagnetic shield to adjust the value of the inductance from the first inductive value to the second inductive value.

60. The shielded component or network of claim 1, wherein the electromagnetic shield comprises a housing for a passive fixation tip.

61. The shielded component or network of claim 1, wherein the electromagnetic shield is associated with a translational active fixation tip.

62. The shielded component or network of claim 61, wherein a housing for the active fixation tip comprises the electromagnetic shield.

63. The shielded component or network of claim 61, wherein the electromagnetic shield is disposed within a housing for the active fixation tip.

64. The shielded component or network of claim 1, wherein the network includes an active electronic circuit.

65. The shielded component or network of claim 1, wherein the electromagnetic shield comprises a non-metallic material having a thin conductive coating applied thereto.

66. The shielded component or network of claim 65, wherein the non-metallic material comprises sapphire, ruby, alumina or ceramic material.

67. The shielded component or network of claim 65, wherein the conductive coating is applied by plating, chemical vapor deposition, sputtering, physical application or cladding.

68. The shielded component or network of claim 1, wherein the electromagnetic shield surrounds less than the entire length of the lead.

69. The shielded component network of claim 1, wherein magnetic field lines through the inductive component are aligned generally parallel with the electromagnetic shield.

70. The shielded component network of claim 1, wherein magnetic field lines through the inductive component are aligned generally orthogonal with the electromagnetic shield.