Co-extruded, multi-lumen medical lead

The present invention relates to medical electrical leads for sensing or electrical stimulation of body organs or tissues and their method of fabrication, such leads having multiple electrical conductors encased in a lead body, and particularly to implantable cardiac leads for delivering electrical stimulation to the heart, e.g., pacing pulses and cardioversion/defibrillation shocks, and/or sensing the cardiac electrogram (EGM) or other physiologic data. Medical electrical leads for sensing or electrical stimulation of body organs or tissues, particularly implantable cardiac leads for delivering pacing pulses and cardioversion/defibrillation shocks, and/or sensing the cardiac electrogram (EGM) or other physiologic data and their methods of fabrication are disclosed. A lead body sheath is co-extruded in a co-extrusion process using bio-compatible, electrically insulating, materials of differing durometers in differing axial sections thereof, resulting in a unitary lead body sheath having differing stiffness sections including axial segments or webs or lumen encircling rings or other structures in its cross-section. The lead body sheath is co-extruded to have an outer surface adapted to be exposed to the environment or to be enclosed within an outer sheath and to have a plurality of lead conductor lumens for receiving and enclosing a like plurality of lead conductors of the same or differing types. The lead body sheath can be co-extruded of a plurality of sheath segments containing a lead conductor lumen and formed of a first durometer material or of differing durometer materials. A web of a further durometer material can be co-extruded extending between the adjoining boundaries of the axial sheath segments and bonding the adjacent segments together. The lead body sheath can be tailored to exhibit differing bending stiffnesses away from the lead body sheath axis in selected polar directions around 360° circumference of the sheath body.