The centennial of the Einthoven electrocardiogram.

Recording of the electrocardiogram by string galvanometer evolved a century ago from wide-ranging advances in physiology, physics, and engineering. Although body surface recordings had been obtained prior to the work of Willem Einthoven, his ingenuity in mathematically correcting capillary electrometer tracings and incorporating recent advances in electromagnetism, recording technology, optics, and quartz chemistry into the new instrument led to a fundamental tool for the investigation of the heart. For his work, Einthoven received the Nobel Prize.