IMPLANTABLE LEAD BANDSTOP FILTER EMPLOYING AN INDUCTIVE COIL WITH PARASITIC CAPACITANCE TO ENHANCE MRI COMPATIBILITY OF ACTIVE MEDICAL DEVICES

• US 20120071956A1
• Filed: 10/19/2011
• Published: 03/22/2012
• Est. Priority Date: 06/08/2006
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Stevenson, Robert A., Halperin, Henry R., Lardo, Albert C., Dabney, Warren S., Kondabatni, Kishore Kumar, Frysz, Christine A., Johnson, Robert Shawn, Moschiano, Holly Noelle
• Granted Patent: US 8,903,505 B2
• Time in Patent Office: Days
• US Class Current: 607/117
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• 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 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• 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: 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 2001/005 Wound, ring or feed-through type inductor
• CPC Class Codes: H03H 2007/013 Notch or bandstop filters
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence

Abstract

A medical lead system includes at least one bandstop filter for attenuating current flow through the lead across a range of frequencies. The bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz. The values of capacitance and inductance of the bandstop filter are selected such that the bandstop filter is resonant at a selected center frequency or range of frequencies. Preferably, the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 10 kHz. Such bandstop filters are backwards compatible with known implantable deployment systems and extraction systems.

Claims

1. A medical lead, comprising:

a lead conductor having a distal electrode contactable with biological cells; and

a bandstop filter comprising at least a portion of the lead conductor, for attenuating RF current flow through the lead conductor at a selected center frequency or across a range of frequencies;

wherein the bandstop filter comprises a capacitance in parallel with an inductance, said parallel capacitance and inductance placed in series with the lead conductor, wherein values of capacitance and inductance are selected such that the bandstop filter attenuates RF current flow at the selected center frequency or across the range of frequencies;

wherein the bandstop filter has an overall circuit Q such that the resultant 3 dB bandwidth is at least 10 kHz; and

wherein the bandstop filter is formed as at least a part of a coiled or spiral inductor portion of the lead conductor, and the capacitance is the parasitic capacitance formed between adjacent turns of said inductor portion.

2. The lead of claim 1, wherein the bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 100 kHz.

3. The lead of claim 2, wherein the bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is on the order of megahertz and at least 0.5 MHz.

4. The lead of claim 3, wherein the bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is on the order of MHz and is at least 10 MHz.

5. The lead of claim 1, wherein the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 25 kHz.

6. The lead of claim 5, wherein the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 200 kHz.

7. The lead of claim 6, wherein the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is on the order of MHz and at least 0.5 MHz.

8. The lead of claim 1, wherein at least the coiled or spiral inductor portion of the conductor is insulated with a dielectric material.

9. The lead of claim 8, wherein the dielectric material comprises polyimide, aromatic polyimide, liquid crystal polymer, PTFE, PEEK, ETFE, Parylene, tantalum oxides, iridium oxides, niobium oxides, hafnium oxides, ruthenium oxides, SiO₂, Si₃N₄, Al₂O₃, Y₂O₃, La₂O₃, Ta₂O₅, TiO₂, HfO₂, ZrO₂, any nano-dielectric coating, PFA, FEP, Polyurethane, polyurethane with self-bonding overcoat, polyamide, polyvinyl acetal, polyvinyl acetal overcoated with polyamide, polyurethane overcoated with polyamide, epoxy, polyester (amide) (imide) overcoated with polyamide, polyester (amide) (imide), silicone-treated glass fiber, polyamide-imide, thermoplastic compounds, polyvinylchloride (PVC), polylefin class:

{LDPE, HDPE, TPO, TPR, polyolefin alloys}, LDPE low density, HDPE high density, polypropylene (PP), thermoplastic fluoropolymers, TEFLON FEP, Tefzel ETFE, Kynar PVDF, TEFLON PFA, Halar ECTFE, PTFE Teflon, PTFE Teflon film, XLPE &

XLPVC, silicone rubber, Polyimide Kapton film, Polyester Mylar film, Kaladex PEN film, or a crosslinked polyalkene.

10. The lead of claim 8, wherein the dielectric material has a dielectric constant greater than 1 up to 100.

11. The lead of claim 1, wherein the medical device comprises a cochlear implant, a piezoelectric sound bridge transducer, a neurostimulator, a brain stimulator, a cardiac pacemaker, a ventricular assist device, an artificial heart, a drug pump, a bone growth stimulator, a bone fusion stimulator, a urinary incontinence device, a pain relief spinal cord stimulator, an anti-tremor stimulator, a gastric stimulator, an implantable cardioverter defibrillator, a pH probe, a congestive heart failure device, a neuromodulator, a cardiovascular stent, a probe or a catheter.

12. The lead of claim 1, wherein the overall Q of the bandstop filter is selected to balance impedance at a selected frequency versus frequency band width characteristics.

13. The lead of claim 1, wherein a Q_i of the inductor portion is relatively high and a Q_c of the capacitance is relatively low to select the overall Q of the bandstop filter.

14. The lead of claim 1, wherein a Q_i of the inductor portion is relatively low and a Q_c of the capacitance is relatively high to select the overall Q of the bandstop filter.

15. The lead of claim 8, wherein a Q_i of the inductor portion is increased by reducing resistive loss in the inductor portion.

16. The lead of claim 8, wherein a Q_i of the inductor portion is decreased by increasing resistive loss in the inductor portion.

17. The lead of claim 14, wherein a Q_c of the capacitance is reduced by raising the equivalent series resistance of the capacitance.

18. The lead of claim 15, wherein a Q_c of the capacitance is increased by lowering the equivalent series resistance of the capacitance.

19. The lead of claim 1, wherein the range of selected frequencies includes a plurality of MRI RF pulsed frequencies.

20. The lead of claim 1, wherein the bandstop filter is disposed at, adjacent to, or within the distal electrode.

21. The lead of claim 1, wherein the bandstop filter is integrated into a Tip electrode or a Ring electrode.

22. The lead of claim 1, wherein the bandstop filter is at least partially housed within a heat dissipating shield.

23. The lead of claim 21 including a thermally conductive material disposed between the bandstop filter and the heat dissipating shield.

24. The lead of claim 1, including at least one conductive end cap conductively connected to the coiled or spiral inductor portion.

25. The lead of claim 1, wherein the shape of the conductor of the coiled or spiral inductor portion comprises a rectangular or square cross-sectional configuration.

26. The lead of claim 1, wherein the bandstop filter resonates at the selected center frequency or across the range of frequencies and also at one or more of its harmonic frequencies.

27. The lead of claim 1, including electrical insulation for attenuating RF currents and body fluids and tissues from degrading the impedance of the bandstop filter at resonance.

28. The lead of claim 26, wherein the insulation is contiguous with an overall insulation of the lead conductor.

29. The lead of claim 1, including electrical insulation for attenuating RF currents and body fluids or tissues from degrading the impedance of the bandstop filter at resonance, the electrical insulation comprising an insulative sleeve disposed about the coiled or spiral inductor portion of the implanted conductor.

30. The lead of claim 1, wherein the coiled or spiral inductor portion of the lead conductor has separate distinct segments having different cross-sectional areas to form a plurality of bandstop filters which resonate at different selected center frequencies or across different ranges of frequencies.

31. The lead of claim 1, wherein the coiled or spiral inductor portion of the lead conductor includes distinct segments having different numbers of turns to form distinct bandstop filters which resonate at different selected center frequencies or across different ranges of frequencies.

33. The lead of claim 31, wherein the capacitance is formed by a discrete passive capacitor component.

34. The lead of claim 31, wherein the inductance is formed by a discrete passive inductor, including an inductor chip, an inductor winding, an inductor meander or an inductor trace.

35. The system of claim 31, wherein the bandstop filter is formed as at least a part of a coiled or spiral inductor portion of the implantable lead conductor, and the capacitance is the parasitic capacitance between adjacent turns of said inductor or portion;

and

wherein at least the coiled or spiral inductor portion of the conductor is insulated with a dielectric material.

36. The lead of claim 31, wherein the bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is on the order of megahertz and at least 0.5 MHz.

37. The lead of claim 31, wherein the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is on the order of MHz and at least 0.5 MHz.

38. The lead of claim 34, wherein the dielectric material comprises polyimide, aromatic polyimide, liquid crystal polymer, PTFE, PEEK, ETFE, Parylene, tantalum oxides, iridium oxides, niobium oxides, hafnium oxides, ruthenium oxides, SiO₂, Si₃N₄, Al₂O₃, Y₂O₃, La₂O₃, Ta₂O₅, TiO₂, HfO₂, ZrO₂, any nano-dielectric coating, PFA, FEP, Polyurethane, polyurethane with self-bonding overcoat, polyamide, polyvinyl acetal, polyvinyl acetal overcoated with polyamide, polyurethane overcoated with polyamide, epoxy, polyester (amide) (imide) overcoated with polyamide, polyester (amide) (imide), silicone-treated glass fiber, polyamide-imide, thermoplastic compounds, polyvinylchloride (PVC), polylefin class:

{LDPE, HDPE, TPO, TPR, polyolefin alloys}, LDPE low density, HDPE high density, polypropylene (PP), thermoplastic fluoropolymers, TEFLON FEP, Tefzel ETFE, Kynar PVDF, TEFLON PFA, Halar ECTFE, PTFE Teflon, PTFE Teflon film, XLPE &

XLPVC, silicone rubber, Polyimide Kapton film, Polyester Mylar film, Kaladex PEN film, or a crosslinked polyalkene.

39. The lead of claim 31, wherein the range of selected frequencies includes a plurality of MRI RF pulsed frequencies.

40. The lead of claim 1, wherein the bandstop filter is at least partially housed within a heat dissipating shield.

41. The lead of claim 39 including a thermally conductive material disposed between the bandstop filter and the heat dissipating shield.

42. The lead of claim 34, wherein the shape of the conductor of the coiled or spiral inductor portion comprises a rectangular or square cross-sectional configuration.

43. The lead of claim 34, wherein the bandstop filter resonates at the selected center frequency or across the range of frequencies and also at one or more of its harmonic frequencies.

44. The lead of claim 34, including electrical insulation for attenuating RF currents and body fluids and tissues from degrading the impedance of the bandstop filter at resonance.

45. The lead of claim 34, wherein the coiled or spiral inductor portion of the lead conductor has separate distinct segments having different cross-sectional areas to form a plurality of bandstop filters which resonate at different selected center frequencies or across different ranges of frequencies.

46. The lead of claim 34, wherein the coiled or spiral inductor portion of the lead conductor includes distinct segments having different numbers of turns to form distinct bandstop filters which resonate at different selected center frequencies or across different ranges of frequencies.

47. The lead of claim 34, wherein the inductance is inherently derived from the lead'"'"'s material of construction or structure.

48. The lead of claim 34, wherein the capacitance is inherently derived from the lead'"'"'s material of construction or structure.

49. The lead of claim 48, wherein the inductance is inherently derived from the lead'"'"'s material of construction or structure.

32. An implantable lead, comprising:

a conductor extending therefrom and a distal electrode contactable with biological cells; and

a bandstop filter comprising at least a portion of the lead conductor, for attenuating current flow through the lead conductor at a selected center frequency or across a range of frequencies,

wherein the bandstop filter comprises a capacitance in parallel with an inductance, said parallel capacitance and inductance placed in series with the lead conductor, wherein values of capacitance and inductance are selected such that the bandstop filter is resonant at the selected center frequency or range of frequencies;

wherein the bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz and the resultant 10 dB bandwidth is at least 25 kHz.