The scene is familiar to anyone who has seen a TV medical drama. The old man on the gurney goes into cardiac arrest, his heart monitor emitting an urgent whine. A doctor grabs a paddle in each hand, barks a warning -- Clear! -- and applies a jolt of electricity to the patient's bare chest. The body thrashes violently, but a tense moment later, the monitor resumes its steady beeping.

That this procedure is instantly recognizable to people who've never set foot in an emergency room is largely due to Boston physician Bernard Lown, inventor of the modern defibrillator. It wasn't always clear that passing current through a patient's body could restore a wayward heart. In 1775, a Danish veterinarian used electricity to stun and revive a chicken. It wasn't until 1955, though, that physician Paul Zoll resuscitated a human patient by applying a burst of alternating current to his chest. AC defibrillation didn't have a high success rate, but since its recipients were nearly dead anyway, its drawbacks did not receive much scrutiny.