Methods and apparatus for fabricating leads with conductors and related flexible lead configurations
MRI/RF compatible leads include at least one conductor, a respective conductor having at least one segment with a multi-layer stacked coil configuration. The lead can be configured so that the lead heats local tissue less than about 10 degrees Celsius (typically about 5 degrees Celsius or less) or does not heat local tissue when a patient is exposed to target RF frequencies at a peak input SAR of at least about 4 W/kg and/or a whole body average SAR of at least about 2 W/kg. Related leads and methods of fabricating leads are also described.
1. An implantable medical lead having a proximal end and a distal end, the lead comprising:
an outer layer of a biocompatible, non-conductive polymer material extending along a portion of the lead;
a plurality of electrodes disposed along the distal end of the lead;
a plurality of contacts disposed along the proximal end of the lead;
a plurality of insulated conductors extending along the lead and electrically coupling the electrodes to the contacts, each insulated conductor defining a plurality of current suppression modules covered by the outer layer of the biocompatible, non-conductive polymer material, each current suppression module comprising a first forward section that extends in a forward lengthwise direction, then turns into a reverse section that extends in a reverse lengthwise direction opposite the forward lengthwise direction, then turns into a second forward section that extends in the forward lengthwise direction, wherein at least one of the first forward section, the reverse section, or the second forward section comprises a coil.
2. The lead of claim 1 , wherein each insulated conductor electrically couples one of the electrodes to one of the contacts.
3. The lead of claim 1 , wherein the first forward section, the reverse section, and the second forward section overlap.
4. The lead of claim 1 , wherein each of the first forward section, the reverse section, and the second forward section comprises a coil.
5. The lead of claim 4 , wherein at least two of the coils interleave.
6. The lead of claim 5 , wherein exactly two of the coils interleave.
7. The lead of claim 6 , wherein the two interleaved coils are disposed around a third one of the coils.
8. The lead of claim 4 , wherein the coils of the first forward section, the reverse section, and the second forward section form a stack with a first one of the coils being an inner layer coil, a second one of the coils being an intermediate layer coil disposed around the inner layer coil, and a third one of the coils being an outer layer coil disposed around the intermediate layer coil.
9. The lead of claim 8 , wherein the coil of the reverse section is the intermediate layer coil.
10. The lead of claim 1 , wherein the reverse section comprises the coil.
11. The lead of claim 10 , wherein the first forward section, the reverse section, and the second forward section form a stack.
12. The lead of claim 11 , wherein the reverse section is between the first forward section and the second forward section in the stack.
13. The lead of claim 11 , wherein a portion of at least one of the first forward section or the second forward section passes through the coil of the reverse section.
14. An implantable medical lead having a proximal end and a distal end, the lead comprising:
a plurality of electrodes disposed along the distal end of the lead:
a plurality of contacts disposed along the proximal end of the lead;
a plurality of insulated conductors extending along the lead and electrically coupling the electrodes to the contacts, each insulated conductor defining a plurality of current suppression modules, each current suppression module comprising a first forward section that extends in a forward lengthwise direction and comprises a first coil, then turns into a reverse section that extends in a reverse lengthwise direction opposite the forward lengthwise direction and comprises a second coil, then turns into a second forward section that extends in the forward lengthwise direction and comprises a third coil, wherein the first, second, and third coils form a stack.
15. The lead of claim 14 , wherein two of the first coil, the second coil, or the third coil interleave.
16. The lead of claim 15 , wherein one of the first coil or the third coil is interleaved with the second coil.
17. The lead of claim 14 , wherein a first one of the first coil, the second coil, or the third coil is an inner layer coil, a second one of the first coil, the second coil, or the third coil is an intermediate layer coil disposed around the inner layer coil, and a third one of the first coil, the second coil, or the third coil is an outer layer coil disposed around the intermediate layer coil.
18. The lead of claim 17 , wherein the second coil is the intermediate layer coil.
19. The lead of claim 14 , wherein each insulated conductor electrically couples one of the electrodes to one of the contacts.
20. The lead of claim 14 , further comprising an outer layer of a biocompatible, non-conductive polymer material disposed around and covering each of the current suppression modules.