External cardiac pacemaker. "The medical world took notice when Zoll announced in 1952 that he had successfully kept a patient alive through numerous episodes of ventricular standstill using a bedside device that delivered electrical pulses to the heart." (Jeffrey, Machines in our hearts (2001) 37).
"There are two kinds of cardiac rhythm disturbances in patients who have cardiac arrest - the rhythm disturbance of a heart in standstill; and the rhythm disturbance of a 'fibrillating' heart, which are the commonest causes of death in acute heart attacks. The effective techniques that now help to control these disturbances are the pioneering contributions of Dr. Paul M. Zoll. Dr. Zoll demonstrated for the first time in 1952, that when a human heart stops, it can be induced, by externally applied electric stimulation, to resume beating. Dr. Zoll's later studies showed that externally applied alternating current countershocks are similarly effective in stopping ventricular fibrillation." Mary Lasker and Michael DeBakey, in "Citations" (quoted by W. Bruce Fye).