Shielded network for an active medical device implantable lead

• US 8,437,865 B2
• Filed: 09/27/2010
• Issued: 05/07/2013
• Est. Priority Date: 04/13/2001
• Status: Expired due to Term

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Dabney, Warren S., Johnson, Robert Shawn, Stevenson, Robert A., Halperin, Henry R., Lardo, Albert C., Kondabatni, Kishore Kumar, Mosciano, Holly Noelle
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US12/891,292
• Publication Number:
  US 20110054582A1
• Time in Patent Office: 953 Days
• Field of Search: 607/116
• 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. An implantable lead configured to be permanently or removably connectable to an active implantable medical device, comprising:

a) a conductor having a length extending from a proximal end to a distal end;

b) a distal electrode contactable with biological cells disposed at the distal end of the conductor;

c) a bandstop filter disposed in series along the length of the conductor, the bandstop filter comprising a self-resonant inductor having an inductance in parallel with a capacitance; and

d) an electromagnetic shield substantially surrounding the bandstop filter;

e) wherein the bandstop filter comprises a first resonant center frequency when removed from the surrounding relationship with the electromagnetic shield and a second resonant center frequency when in the surrounding relationship with the electromagnetic shield;

f) wherein the inductance or capacitance is adjusted to account for a shift between the first and second resonant center frequencies;

g) wherein the bandstop filter comprises an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz, such that the bandstop filter

attenuates RF current flow substantially about the

second resonant center frequency.

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

3. The lead of claim 1 wherein the bandstop filter is disposed near, at or within the distal electrode.

4. The lead of claim 1 wherein the electromagnetic shield comprises an energy dissipating surface.

5. The lead of claim 1 wherein the electromagnetic shield is selected from the group consisting of a solid conductor, a wound spiral conductor, a mesh, a tubing, a nanocoating, a conductive heat-shrink tubing, a conductive foil, a wire, a braid, a circuit. trace, a solid tubular material, a conductive polymer, a conductive epoxy, a carbon nano-fiber, a nano-mesh, a nano-coating, and a nano-thread.

6. The lead of claim 1 wherein the electromagnetic shield comprises an open ended tubular or cylindrical shield.

7. The lead of claim 1 wherein the inductance is formed by a discrete passive inductor.

8. The lead of claim 7 wherein the discrete passive inductor is selected from the group consisting of an inductor chip, an inductor winding, an inductor meander, a solenoid inductor or an inductor trace.

9. The lead of claim 1 wherein the capacitance is formed by a discrete passive capacitor.

10. The lead of claim 9 wherein the discrete passive capacitor comprises a chip capacitor or a feedthrough capacitor.

11. The lead of claim 1 wherein the capacitance comprises parasitic capacitance.

12. The lead of claim 1 wherein the bandstop filter inductance is selected from the group consisting of a coiled or spiral inductor, and the capacitance comprises a parasitic capacitance between adjacent turns of the coiled, and spiral inductor.

13. The lead of claim 12 wherein the coiled or spiral inductor comprises a dielectric material surrounding the coiled or spiral inductor, such that adjacent turns of the coiled or spiral inductor are insulated from each other and the shield.

14. The lead of claim 13 wherein the dielectric material has a dielectric constant greater than 1 up to 100.

15. The lead of claim 1 wherein the bandstop filter inductance comprises a coiled or spiral inductor, and the capacitance comprises a parasitic capacitance between the turns of the coiled or spiral inductor and the shield.

16. The lead of claim 1 wherein the shift between the first and second resonant center frequencies is greater than 3.0 mHz or 4.5%.

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

a) a conductor having a length extending from a proximal end to a distal end;

b) a distal electrode contactable with biological cells disposed at the distal end of the conductor;

c) a bandstop filter disposed in series near, at or within the distal electrode, the bandstop filter comprising a self-resonant inductor, wherein a bandstop filter inductance is formed by an insulated coiled or spiral inductor, and wherein a bandstop filter capacitance comprises a parasitic capacitance between adjacent turns of the insulated coiled or spiral inductor; and

d) an electromagnetic shield substantially surrounding the bandstop filter;

e) wherein the bandstop filter comprises a first resonant center frequency when removed from the surrounding relationship with the electromagnetic shield and a second resonant center frequency when in the surrounding relationship with the electromagnetic shield;

f) wherein the inductance or capacitance is adjusted to account for a shift between the first and second resonant center frequencies;

g) wherein the bandstop filter comprises an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz, such that the bandstop filter attenuates RF current flow substantially about the second resonant center frequency.

18. The lead of claim 17 wherein the second resonant center frequency is an MR1 RF pulsed frequency.

19. The lead of claim 17 wherein the electromagnetic shield comprises an energy dissipating surface,

20. The lead of claim 17 wherein the electromagnetic shield is selected from the group consisting of a solid conductor, a wound spiral conductor, a mesh, a tubing, a nanocoating, a conductive heat-shrink. tubing, a conductive foil, a wire, a braid, a circuit trace, a solid tubular material, a conductive polymer, a conductive epoxy, a carbon nano-fiber, a nano-mesh, a nano-coating, and a nano-thread.

21. The lead of claim 17 wherein the electromagnetic shield comprises an open ended tubular or cylindrical shield.

22. The lead of claim 17 wherein the coiled or spiral inductor comprises a dielectric material surrounding the coiled or spiral inductor.

23. The lead of claim 22 wherein the dielectric material has a dielectric constant greater than 1 up to 100.

24. The lead of claim 22 wherein the dielectric material surrounding the coiled or spiral inductor comprises a dielectric wrapping substantially disposed along the entire length of the coiled or spiral inductor.

25. The lead of claim 17 wherein the capacitance further comprises a parasitic capacitance between the adjacent turns of the insulated coiled or spiral inductor and the electromagnetic shield.

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

a) a conductor having a length extending from a proximal end to a distal end;

b) a distal electrode contactable with biological cells disposed at the distal end of the conductor;

c) a passive electrical component disposed in series along the length of the conductor, the passive electrical component comprising a resonant filter circuit including at least one inductor; and

d) an electromagnetic shield substantially surrounding the passive electrical component;

e) wherein the at least one inductor comprises a first inductance value when removed from the surrounding relationship with the electromagnetic shield and a second inductance value when in the surrounding relationship with the electromagnetic shield;

f) wherein the first inductance value and the second inductance value change a resonant frequency of the passive electrical component;

g) wherein the passive electrical component comprises an overall circuit Q, wherein the resultant 3 dB bandwidth is at least 10 kHz, such that the passive electrical component attenuates RE pulsed current flow substantially about the resonant frequency resulting from the second inductance value, wherein the resonant frequency comprises an MRI RF pulsed frequency.

27. The lead of claim 26 wherein the electromagnetic shield is selected from the group consisting of a solid conductor, a wound spiral conductor, a mesh, a tubing, a nanocoating, a conductive heat-shrink tubing, a conductive foil, a wire, a braid, a circuit trace, a solid tubular material, a conductive polymer, a conductive epoxy, a carbon nano-fiber, a nano-mesh, a nano-coating, and a nano-thread.

28. The lead of claim 27 wherein the discrete passive inductor is selected from the group consisting of an inductor chip, an inductor winding, an inductor meander, a solenoid inductor, and an inductor trace.

29. An implantable lead, comprising:

a) a conductor having a length extending from a proximal end to a distal end;

b) an electrode connectable with biological tissue disposed at the distal end of the conductor;

c) a bandstop filter disposed in series near, at or within the electrode, the bandstop filter comprising a self-resonant inductor having an inductance in parallel with a capacitance; and

d) an electromagnetic shield substantially surrounding the bandstop filter;

e) wherein the bandstop filter comprises a first resonant center frequency when removed from the surrounding relationship with the electromagnetic shield and a second resonant center frequency when in the surrounding relationship with the electromagnetic shield;

f) wherein the inductance or capacitance is adjusted to account for a shift between the first and second resonant center frequencies;

g) wherein the bandstop filter comprises an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz, such that the bandstop filter attenuates RF current flow substantially about the second resonant center frequency.

30. The lead of claim 29 wherein the second resonant center frequency comprises an MRI RF pulsed frequency.

31. The lead of claim 29 wherein the electromagnetic shield comprises an energy dissipating surface.

32. The lead of claim 29 wherein the electromagnetic shield is selected from the group consisting of a solid conductor, a wound spiral conductor, a mesh, a tubing, a nanocoating, a conductive heat-shrink. tubing, a conductive foil, a wire, a braid, a circuit trace, a solid tubular material, a conductive polymer, a conductive epoxy, a carbon nano-fiber, a nano-mesh, a nano-coating, and a nano-thread.

33. The lead of claim 29 wherein the inductance is formed by a discrete passive inductor.

34. The lead of claim 33 wherein the discrete passive inductor is selected from the group consisting of an inductor chip, an inductor winding, an inductor meander, a solenoid inductor, and an inductor trace.

35. The lead of claim 29 wherein the capacitance is formed by a discrete passive capacitor.

36. The lead of claim 35 wherein the discrete passive capacitor comprises a chip capacitor or a feedthrough capacitor.

37. The lead of claim 29 wherein the bandstop filter inductance comprises a coiled or spiral inductor, and the capacitance comprises a parasitic capacitance between adjacent turns of the coiled or spiral inductor and the capacitance comprises a parasitic capacitance between the turns of the coiled or spiral inductor and the shield.

38. The lead of claim 37 wherein the coiled or spiral inductor comprises a dielectric material, surrounding the coiled or spiral inductor.

39. The lead of claim 38 wherein the dielectric material has a dielectric constant greater than 1 up to 100.

40. The lead. of claim 29 wherein the shift between the first and second resonant center frequencies is greater than 3.0 mHz or 4.5%.

41. The lead of claim 29 including a torque carrier attached between the distal end of the conductor and the electrode, the torque carrier disposed mechanically in parallel to the bandstop filter, such that torque experienced by the electrode when inserted into the biological tissue is not transmitted to the bandstop filter.

42. An implantable lead, comprising:

a) a conductor having a length extending from a proximal end to a distal end;

b) a distal electrode contactable with biological cells disposed at the distal end of the conductor; and

c) an LC circuit disposed in series along the length of the conductor, the LC circuit comprising a self resonant inductor having an inductance in parallel with a capacitance, wherein the LC circuit is shielded;

d) wherein the LC circuit comprises a first resonant center frequency when removed from the surrounding relationship with the electromagnetic shield and a second resonant. center frequency when in the surrounding relationship with the electromagnetic shield;

e) wherein the inductance or capacitance is adjusted to account for a shift between the first and second resonant frequencies;

f) wherein the LC circuit comprises an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz, such that the LC circuit attenuates RF current flow substantially about the second resonant center frequency;

g) wherein the second resonant center frequency comprises an MRI RF pulsed frequency.

43. The lead of claim 42 wherein the LC circuit is disposed near, at or within the distal electrode.

44. The lead of claim 42 wherein the electromagnetic shield comprises an energy dissipating surface.

45. The lead of claim 42 wherein the electromagnetic shield comprises an open ended tubular or cylindrical shield.

46. The lead of claim 42 wherein the inductance is formed by a discrete passive inductor.

47. The lead of claim 46 wherein the discrete passive inductor is selected from the group consisting of an inductor chip, an inductor winding, an inductor meander, a solenoid inductor, and an inductor trace.

48. The lead of claim 42 wherein the capacitance is formed by a discrete passive capacitor.

49. The lead of claim 48 wherein the discrete passive capacitor comprises a chip capacitor or a feedthrough capacitor.

50. The lead of claim 42 wherein the LC circuit inductance comprises a coiled or spiral inductor, and the capacitance comprises a parasitic capacitance between adjacent turns of the coiled or spiral inductor.

51. The lead of claim 50 wherein the coiled or spiral inductor comprises a dielectric material surrounding the coiled or spiral inductor, such that adjacent turns of the coiled or spiral inductor are insulated from each other and the shield.

52. The lead of claim 51 wherein. the dielectric material has a dielectric constant greater than 1 up to 100.

53. The lead of claim 52 wherein the LC circuit inductance comprises a coiled or spiral inductor, and the capacitance comprises a parasitic capacitance between the turns of the coiled or spiral inductor and the shield.