extrasystole

a heartbeat that is outside the normal rhythm of the HEART and is the result of an impulse generated outside the SINOATRIAL NODE . It may go unnoticed or it may seem that the heart has missed a beat. Extrasystoles are common in healthy people, but they may result from heart disease or nicotine from smoking, or caffeine from excessive intake of tea and coffee. Drugs can be taken to suppress these irregular beats.