Cardiac arrhythmias are heart-rhythm disorders. Most arrhythmias are not life threatening, and many are benign. But some rhythm disturbances originating in the ventricles—the heart's main pumping chambers—can be fatal.
Visual observations of animal hearts, documented at least as far back as the 16th century, revealed that the exposed surface of a ventricular wall can break down into worm-like regions or “fibrils” that appear to twitch randomly before death. In an article published in 1874, the French physician and neurologist Edmé Vulpian coined the term mouvement fibrillaire to describe the quivering motion that stops the heart from pumping.
In a human heart, ventricular fibrillation is almost always fatal. It is generally preceded by a very rapid rhythm known as ventricular tachycardia. Roughly half of the deaths caused by cardiovascular disease are sudden. The majority of those sudden deaths—an estimated 300 000 per year in the US—are associated with ventricular fibrillation.
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