fibrillation

Rapid and disordered beating of a section of heart muscle. It may occur in different chambers of the heart. Atrial fibrillation, producing a rapid, chaotic heartbeat, occurs in a number of conditions, including atherosclerosis, rheumatic heart disease and hyperthyroidism. Ventricular fibrillation causes cardiac arrest; it occurs mostly after a heart attack.

In 1998 US cardiologists identified a mutation of the gene controlling for the cardiac sodium channel that affects heart beat.

There are 300,000 sudden deaths per year in the USA, from ventricular fibrillation. In 30,000 of these cases there is no underlying disease identified, indicating that there is some genetic susceptibility.