Composite RF current attenuator for a medical lead

1. An implantable device, comprising:

a) at least one lead conductor having a length extending from a proximal conductor end to a distal conductor portion having a distal conductor end, wherein the proximal conductor end is electrically connectable to an active implantable medical device;

b) at least one electrode electrically connected to the distal conductor portion or the distal conductor end, wherein the electrode is contactable with biological cells; and

c) wherein the at least one lead is a coiled conductor comprising at least two portions of varying spacing between adjacent turns, the at least two portions comprising a first spacing portion having a larger spacing between adjacent turns as compared to a second spacing portion;

d) wherein the first spacing portion comprises a first inductance formed from the turns of the single coiled conductor along the first spacing portion; and

e) wherein the second spacing portion comprises a bandstop filter comprising a self-resonant inductor, wherein the self-resonant inductor comprises a second inductance formed from the turns of the single coiled conductor along the second spacing portion and

e) wherein a bandstop filter capacitance comprises parasitic capacitance formed between the adjacent turns of the coiled conductor along the second spacing portion.

2. The implantable device of claim 1 , wherein the bandstop filter is configured to attenuate the MRI RF pulsed frequency at or near a center frequency or across a range of frequencies about the center frequency.

3. The implantable device of claim 2 , wherein an inductance resistance and a capacitance resistance of the bandstop filter results in a 3-dB bandwidth that is at least 10 kHz so that the bandstop filter attenuates the MRI RF pulsed frequency about the center frequency.

4. The implantable device of claim 2 , wherein an inductance resistance and a capacitance resistance of the bandstop filter results in a 3-dB bandwidth is at least 100 kHz so that the bandstop filter attenuates the MRI RF pulsed frequency about the center frequency.

5. The implantable device of claim 2 , wherein an inductance resistance and a capacitance resistance of the bandstop filter results in a 3-dB bandwidth is at least 0.5 MHz so that the bandstop filter attenuates the MRI RF pulsed frequency about the center frequency.

6. The implantable device of claim 1 , including a dielectric coating substantially surrounding the single coiled conductor along the second spacing portion.

7. The implantable device of claim 6 , wherein the dielectric coating is absent substantially surrounding the single coiled conductor along the first spacing portion.

8. The implantable device of claim 1 , wherein the single coiled inductor comprises a round, rectangular or square wire.

9. The implantable device of claim 1 , including a hollow mandrel wherein the single coiled conductor is wrapped around the hollow mandrel.

10. The implantable device of claim 1 , wherein the implantable device is an implantable lead, probe, or catheter.

11. A composite filter circuit for attenuating an MRI RF pulsed frequency in active implantable medical devices or medical leads, the composite filter circuit comprising:

a) a conductor;

b) a first inductance connected in series along the conductor; and

c) a bandstop filter connected in series along the conductor, the bandstop filter comprising a second inductance in parallel with a capacitance;

d) wherein the first inductance and bandstop filter are formed from a single coiled conductor comprising a first and second spacing between adjacent turns of the single coiled conductor;

e) wherein the first inductance is formed from the turns of the single coiled conductor along the first spacing;

f) wherein the second inductance is formed from the turns of the single coiled conductor along the second spacing;

g) wherein the capacitance comprises a parasitic capacitance between the adjacent turns of the single coiled conductor along the second spacing.

12. The composite filter circuit of claim 11 , wherein the coiled conductor comprises a round, rectangular or square wire.

13. The composite filter circuit of claim 11 , wherein the first spacing comprises a larger spacing between adjacent turns of the coiled conductor as compared to the second spacing.

14. The composite filter circuit of claim 11 , wherein the bandstop filter attenuates the MRI RF pulsed frequency at or near a center frequency or across a range of frequencies about the center frequency.

15. The composite filter circuit of claim 11 , wherein an inductance resistance and a capacitance resistance of the bandstop filter determines an overall Q of the bandstop filter, wherein the resultant 3-dB bandwidth is at least 100 kHz so that the bandstop filter attenuates the MRI RF pulsed frequency about the center frequency.

16. The composite filter circuit of claim 11 , wherein an inductance resistance and a capacitance resistance of the bandstop filter determines an overall Q of the bandstop filter, wherein the resultant 3-dB bandwidth is at least 0.5 MHz so that the bandstop filter attenuates the MRI RF pulsed frequency about the center frequency.

17. The composite filter circuit of claim 11 , including a dielectric coating substantially surrounding the single coiled conductor along the second spacing.

18. The composite filter circuit of claim 17 , wherein the dielectric coating is absent substantially surrounding the single coiled conductor along the first spacing.

19. The composite filter circuit of claim 11 , including a hollow mandrel wherein the single coiled conductor is wrapped around the hollow mandrel.