An implantable lead assembly for a body implantable medical system adapted to transmit electrical signals between a proximal end portion of the lead assembly and a distal end portion of the lead assembly to thereby stimulate selected body tissue includes an elongated insulative sheath of flexible resilient material having at least one longitudinally extending lumen, an electrical conductor received within the lumen of the insulative sheath and extending between a proximal end and a distal end, and at least one elongated super plastic element slidably received within the lumen of the insulative sheath, the super plastic element being bendable to configure the lead assembly to negotiate tortuous turns in the vasculature of the body. An electrical connector is coupled to the proximal end of the conductor for releasable attachment to a stimulating pulse generator and an electrode is coupled to the distal end of the conductor.