Abstract: A cardiac monitoring and defibrillation system is provided which may be embodied as a bedside unit or as an ambulatory unit. The system includes amplification and processing circuitry which receives and conditions inputs from a variety of sensing means such as an electrocardiogram, a blood oxygenation sensor, a blood pressure monitor, and a cardiac acoustical transducer. A noise and artifact discrimination procedure is employed to prevent erroneous detection of the onset of cardiac arrhythmias. In response to the conditioned inputs from the monitoring means, the microprocessor controls therapeutic electrical stimulus which may be delivered to a patient in accordance with a cardioverter/defibrillator step therapy method. The microprocessor may be operated or programmed by means of a control panel or an external programming and monitoring unit.