# US 2014/0155972 A1 · Mri conditionally safe lead with low-profile 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 2014/0155972 A1 - Document ID: US20140155972A1 - Status: Published application - Kind: A1 - Application number: 14/174,358 - Filed: 2014-02-06 - Published: 2014-06-05 - Earliest claimed: 2009-12-31 - Assignees: Cardiac Pacemakers, Inc. - Applicants: Cardiac Pacemakers, Inc. - Inventors: Arthur J. Foster; Christopher R. Perrey; Stephen E. DeRoche; Timothy R. Jackson; Andrew L. De Kock - Web page: https://patentgrep.com/patent/US20140155972A1 ## 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 coil conductor extending within the lead body, the coil conductor configured such that the coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the coil conductor. ### Claim 2 (depends on 1) The implantable electrical lead of claim 1, wherein the coil conductor 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 coil conductor is substantially equal to the axial stiffness of the lead body adjacent to the 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 coil conductor are such that the axial stiffness of the coil conductor is substantially equal to the axial stiffness of the lead body adjacent to the coil conductor. ### Claim 4 (depends on 1) The implantable electrical lead of claim 1, wherein the coil conductor is mechanically and electrically connected to an electrode. ### Claim 5 (depends on 4) The implantable electrical lead of claim 4, wherein the 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 disposed over the coil conductor. ### Claim 7 (depends on 1) The implantable electrical lead of claim 1, wherein each filar of the coil conductor is individually insulated. ### Claim 8 (depends on 1) The implantable electrical lead of claim 1, wherein the coil conductor is formed from one or more filars of a silver core drawn filled tube (DFT) wire having an MP35N cladding. ### Claim 9 (depends on 1) The implantable electrical lead of claim 1, wherein a pre-determined spring constant of the coil conductor is such that the lead returns to its original length after axial elongation of the coil conductor. ### Claim 10 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 conductor extending within the longitudinal body lumen and coupled to the electrode, wherein at least one parameter of the coil conductor is configured such that the lead exhibits a predetermined axial stiffness or bending stiffness, wherein the at least one parameter of the coil conductor 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 coil conductor is configured such that the coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the coil conductor. ### Claim 11 (depends on 10) The implantable electrical lead of claim 10, wherein the coil conductor is formed from one or more filars of a silver core drawn filled tube (DFT) wire having an MP35N cladding. ### Claim 12 (depends on 10) The implantable electrical lead of claim 10, wherein the coil conductor is mechanically and electrically connected to a second electrode coupled to the lead body. ### Claim 13 (depends on 12) The implantable electrical lead of claim 12, wherein the coil conductor allows the second electrode to move axially relative to a proximal connector when under tensile load. ### Claim 14 (depends on 10) The implantable electrical lead of claim 10, wherein each of the filars of the coil conductor is individually insulated. ### Claim 15 An implantable electrical lead, comprising: a lead body; and a coil conductor extending within the lead body, wherein at least one parameter of the coil conductor is configured such that the coil conductor has a pre-determined spring constant along at least a portion of its length, and wherein the coil conductor is configured such that the coil conductor has an axial stiffness substantially equal to an axial stiffness of the lead body adjacent to the coil conductor. ### Claim 16 (depends on 15) The implantable electrical lead of claim 15, wherein the pre-determined spring constant is such that the lead returns to its original length after axial elongation of the coil conductor. ### Claim 17 (depends on 15) The implantable electrical lead of claim 15, wherein the coil conductor is mechanically and electrically connected to an electrode coupled to the lead body. ### Claim 18 (depends on 15) The implantable electrical lead of claim 15, wherein the coil conductor is configured to allow the electrode to move axially relative to a proximal connector when under tensile load. ### Claim 19 (depends on 15) The implantable electrical lead of claim 15, further comprising a layer of insulating material disposed over the coil conductor. ### Claim 20 (depends on 15) The implantable electrical lead of claim 15, wherein each filar of the coil conductor is individually insulated.