Abstract: A threaded pacing electrode assembly for use in implantable electrical leads. The electrode is provided with an exposed portion adapted to make electrical contact with body tissue and with a cylindrical portion proximal to the exposed portion provided with a helical screw thread. A conductor coil which has an inner diameter smaller than the outer diameter of the cylindrical portion is mounted to the exterior of the cylindrical portion, coiled within the screw thread. A transparent insulating sleeve covers the cylindrical portion, is frictionally retained by the thread, and assists in maintaining the conductor coils in contact with the cylindrical portion.

Abstract: A body implantable lead which may be provided with a desired predetermined curve. A memory coil is inserted into the lead while straightened by a stylet. After removal of the stylet, the memory coil imparts the desired curve to the lead.

Abstract: A lead having multiple electrodes which is transvenously implanted for use in standby defibrillation of patients having a high risk of ventricular fibrillation. The lead employs four electrodes. The two distal electrodes have a spacing for optimal measurement of impedance changes due to mechanical contractions. This impedance measurement is used for mechanical sensing of normal cardiac activity. The electrode at the very distal tip terminates in a hemispherical shape. Two proximal electrodes are closely spaced and located at a distance from the two distal electrodes which ensures their placement within the superior vena cava whenever the distal electrodes are placed within the right ventricular apex. The body of the lead uses drawn brazed strand conductors wound triaxially for maximum flexibility, minimum cross-sectional area and the required high current carrying capability. At the proximal end of the lead, three connectors are used to electrically couple the lead to an implantable pulse generator.