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

• US 8,391,994 B2
• Filed: 11/05/2010
• Issued: 03/05/2013
• 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
• Primary Examiner(s): Layno, Carl H.
• Assistant Examiner(s): MORALES, JON ERIC C
• Application Number:
  US12/940,489
• Publication Number:
  US 20110160828A1
• Time in Patent Office: 851 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 having a flexible body and including a multi-layer coil conductor extending within the longitudinal body lumen from the connector assembly to at least the electrode, the multi-layer coil conductor including a first coil layer 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.

Claims

1. An implantable electrical lead, comprising:

a flexible lead body having a proximal region including a proximal end, a distal region, and a longitudinal body lumen extending from the proximal end through the distal region;

a connector assembly configured to mechanically and electrically connect the implantable electrical lead to an implantable pulse generator;

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

a multi-layer coil conductor extending within the longitudinal body lumen from the connector assembly to at least the electrode, 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 the each of the first and second coil layers is characterized by 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 selected 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 are further selected 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 a second electrode coupled to the lead body.

5. The implantable electrical lead of claim 4, wherein the multi-layer coil conductor allows the second electrode to move axially relative to the terminal 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 of the filars of the first and second coil layers is individually insulated.

8. An implantable electrical lead, comprising:

a flexible lead body having a proximal region including a proximal end, a distal region, and a longitudinal body lumen extending from the proximal end through the distal region;

a connector assembly configured to mechanically and electrically connect the implantable electrical lead to an implantable pulse generator;

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

a multi-layer coil conductor extending within the longitudinal body lumen from the connector assembly to at least 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 lead of claim 8 wherein each of the coil layers is formed from one or more filars of a silver core 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 the terminal connector when under tensile load.

13. An implantable electrical lead, comprising:

a flexible lead body having a proximal region including a proximal end, a distal region, and a longitudinal body lumen extending from the proximal end through the distal region;

a connector assembly configured to mechanically and electrically connect the implantable electrical lead to an implantable pulse generator;

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

a multi-layer coil conductor extending within the longitudinal body lumen from the connector assembly to at least 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 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.

14. The implantable electrical lead of claim 13 wherein the pre-determined spring constant is sufficient to allow the multi-layer coil conductor to substantially return the lead to its original length upon axial elongation.

15. The implantable electrical lead of claim 13, wherein the multi-layer coil conductor is mechanically and electrically connected to a second electrode coupled to the lead body.

16. The implantable electrical lead of claim 13, wherein the multi-layer coil conductor allows the second electrode to move axially relative to the terminal connector when under tensile load.