# US 2013/0158641 A1 · Mri conditionally safe lead with low-profile multi-layer conductor for longitudinal expansion > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0158641 A1 - Document ID: US20130158641A1 - Status: Published application - Kind: A1 - Application number: 13/767,445 - Filed: 2013-02-14 - Published: 2013-06-20 - Earliest claimed: 2009-12-31 - Assignees: Cardiac Pacemakers, Inc. - Inventors: Arthur J. Foster; Christopher Perrey; Stephen Earl DeRoche; Timothy R. Jackson; Andrew L. De Kock - Web page: https://patentgrep.com/patent/US20130158641A1 ## CPC - A61N 1/056: {Transvascular endocardial electrode systems} - A61N 1/05: for implantation or insertion into the body, e.g. heart electrode (A61N1/06 takes precedence) - A61N 1/3718: {Monitoring of or protection against external electromagnetic fields or currents} - A61N 1/3925: {Monitoring; Protecting} - A61N 1/086: {Magnetic resonance imaging [MRI] compatible leads} - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## 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 ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) The implantable electrical lead of claim 1, wherein the multi-layer coil conductor is mechanically and electrically connected to an electrode. ### Claim 5 (depends on 4) 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. ### Claim 6 (depends on 1) The implantable electrical lead of claim 1, further comprising a layer of insulating material between the first and second coil layers. ### Claim 7 (depends on 1) The implantable electrical lead of claim 1, wherein each filar of the first and second coil layers is individually insulated. ### Claim 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. ### Claim 9 (depends on 8) 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. ### Claim 10 (depends on 8) 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. ### Claim 11 (depends on 8) 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. ### Claim 12 (depends on 11) 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. ### Claim 13 (depends on 8) The implantable electrical lead of claim 8, wherein each of the filars of the first and second coil layers is individually insulated. ### Claim 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. ### Claim 15 (depends on 14) 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. ### Claim 16 (depends on 14) 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. ### Claim 17 (depends on 14) 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. ### Claim 18 (depends on 14) 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. ### Claim 19 (depends on 14) The implantable electrical lead of claim 14, further comprising a layer of insulating material between the first and second coil layers. ### Claim 20 (depends on 14) The implantable electrical lead of claim 14, wherein each filar of the first and second coil layers is individually insulated.