In 1962, Bernard Lown, Barouh Berkovits, and colleagues published in JAMA the introduction of direct current (DC) via controlled capacitor discharge to terminate cardiac arrhythmias, replacing Zoll's alternating current (AC). The Lown waveform — a regulated, synchronized DC discharge — proved much safer and more efficient for the heart than AC. The switch to DC capacitors was the link enabling energy autonomy: instead of depending on mains power, the system could slowly charge energy and release it in a pulse. Pantridge took exactly this principle in 1965 and coupled it to car batteries to create the first portable prehospital defibrillator.