Implantable lead having variable electrode spacing

An implantable lead, comprising:

• an inner lead subassembly including a helical electrode mounted on an inner coil extending along a longitudinal axis;
• and
• an outer lead subassembly including an outer coil having a central lumen containing the inner coil, and a ring electrode mounted on the outer coil, wherein the outer lead subassembly includes a threaded interface having a threaded surface between the outer lead subassembly and the inner lead subassembly, and wherein the threaded surface converts rotation of the inner lead subassembly relative to the outer lead subassembly into relative axial movement of the helical electrode relative to the ring electrode.