Abstract: A transvenous cardioversion lead for use in standby cardioversion in patients who have a high risk of ventricular tachycardia or fibrillation, adapted for use with presently available external defibrillation units. The lead is provided with energy-reducing or energy-limiting circuitry to prevent the inappropriately high energy levels which may be generated by external defibrillation units from causing injury to the patient while preserving the beneficial waveform of the defibrillation pulse. The lead is further provided with at least three electrodes, two for location in the ventricle, at least one for location in the superior vena cava. The lead is so constructed that the superior vena cava electrode and one of the ventricular electrodes may be used for cardioversion, while the two ventricular electrodes may be used for cardiac pacing and sensing.

Abstract: An implantable dispenser for infusing a desired drug into the blood stream. The dispenser is adapted to be spliced into a blood vessel so that blood flows freely through it. Within the dispenser is a replaceable biomass cartridge containing a colony of microorganisms which produce the drug.

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.