MRI conditionally safe lead with low-profile multi-layer conductor for longitudinal expansion

• US 8,676,351 B2
• Filed: 02/14/2013
• Issued: 03/18/2014
• Est. Priority Date: 12/31/2009
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Foster, Arthur J., Perrey, Christopher, DeRoche, Stephen Earl, Jackson, Timothy R., De Kock, Andrew L.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Morales, Jon Eric C
• Application Number:
  US13/767,445
• Publication Number:
  US 20130158641A1
• Time in Patent Office: 397 Days
• Field of Search: 607/119
• US Class Current: 607/119
• 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 1/056 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: A61N 1/3925 Monitoring; Protecting

Abstract

An implantable electrical lead includes a lead body and a multi-layer coil conductor extending within the lead body. The multi-layer coil conductor includes a first coil layer and a second coil layer disposed about the first coil layer. The first and second coil layers are configured such that the multi-layer coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the multi-layer coil conductor.

Claims

1. An implantable electrical lead comprising:

a lead body; and

a multi-layer coil conductor extending within the lead body, the multi-layer coil conductor including a first coil layer and a second coil layer disposed about the first coil layer, wherein the first and second coil layers are configured such that the multi-layer coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the multi-layer coil conductor.

2. The implantable electrical lead of claim 1, wherein each of the first and second coil layers includes a filar having a filar thickness, a coil outside diameter, and a coil pitch, and wherein one or more of the filar thickness, the coil outside diameter, and the coil pitch are such that the axial stiffness of the multi-layer coil conductor is substantially equal to the axial stiffness of the lead body adjacent to the multi-layer coil conductor.

3. The implantable electrical lead of claim 1, wherein a filar material and a coil wind geometry of the first and second coil layers are such that the axial stiffness of the multi-layer coil conductor is substantially equal to the axial stiffness of the lead body adjacent to the multi-layer coil conductor.

4. The implantable electrical lead of claim 1, wherein the multi-layer coil conductor is mechanically and electrically connected to an electrode.

5. The implantable electrical lead of claim 4, wherein the multi-layer coil conductor is configured to allow the electrode to move axially relative to a proximal connector when under tensile load.

6. The implantable electrical lead of claim 1, further comprising a layer of insulating material between the first and second coil layers.

7. The implantable electrical lead of claim 1, wherein each filar of the first and second coil layers is individually insulated.

8. An implantable electrical lead, comprising:

a lead body having a longitudinal body lumen;

an electrode coupled to the flexible body in the distal region; and

a multi-layer coil conductor extending within the longitudinal body lumen and coupled to the electrode, the multi-layer coil conductor including a first coil layer and a second coil layer disposed about the first coil layer, wherein at least one parameter of the first and the second coil layer is configured such that the lead exhibits a predetermined axial stiffness or bending stiffness, wherein the at least one parameter of the first and second coil layers is at least one of a coil filar thickness, a number of filars, a filar material, a coil winding direction, or a coil diameter, and wherein the first and second coil layers are configured such that the multi-layer coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the multi-layer coil conductor.

9. The implantable electrical lead of claim 8, further comprising a third coil layer disposed around the second coil layer, wherein at least one parameter of the third coil layer is configured such that the lead exhibits a predetermined axial bending stiffness.

10. The implantable electrical lead of claim 8 wherein each of the first and second coil layers is formed from one or more filars of a silver core drawn filled tube (DFT) wire having an MP35N cladding.

11. The implantable electrical lead of claim 8, wherein the multi-layer coil conductor is mechanically and electrically connected to a second electrode coupled to the lead body.

12. The implantable electrical lead of claim 11, wherein the multi-layer coil conductor allows the second electrode to move axially relative to a proximal connector when under tensile load.

13. The implantable electrical lead of claim 8, wherein each of the filars of the first and second coil layers is individually insulated.

14. An implantable electrical lead, comprising:

a lead body; and

a multi-layer coil conductor extending within the lead body, the multi-layer coil conductor including a first coil layer and a second coil layer disposed about the first coil layer, wherein at least one parameter of the first and the second coil layer is configured such that the multi-layer coil conductor has a pre-determined spring constant along at least a portion of its length, and wherein the first and second coil layers are configured such that the multi-layer coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the multi-layer coil conductor.

15. The implantable electrical lead of claim 14 wherein the pre-determined spring constant is such that the lead returns to its original length after axial elongation of the multi-layer coil conductor.

16. The implantable electrical lead of claim 14, wherein the multi-layer coil conductor is mechanically and electrically connected to an electrode coupled to the lead body.

17. The implantable electrical lead of claim 14, wherein the multi-layer coil conductor is configured to allow the electrode to move axially relative to a proximal connector when under tensile load.

18. The implantable electrical lead of claim 14, wherein the multi-layer coil further comprises a third coil layer disposed around the second coil layer, wherein at least one parameter of the third coil layer is configured such that the lead exhibits a predetermined axial bending stiffness.

19. The implantable electrical lead of claim 14, further comprising a layer of insulating material between the first and second coil layers.

20. The implantable electrical lead of claim 14, wherein each filar of the first and second coil layers is individually insulated.