Any disturbance of the heart's rhythm resulting in rates less than 60 beats per minute. ... (27 Sep 1997) ... 
(brad″e-ә-rith´me-ә) bradycardia associated with arrhythmia; the rate is 60 beats per minute or less. It is caused by conditions such as sinus bradycardia, sinoatrial block, and atrioventricular block.
Type: Term Pronunciation: brad′ē-ă-ridh′mē-ă Definitions: 1. Any disturbance of the heart's rhythm resulting (by convention) in a rate less than 50 beats/minute.
A slow and irregular heartbeat, usually less than 60 beats per minute.
bradyarrhythmia Any disturbance in the heart rhythm in which the heart rate is abnormally slowed, usually to less than 60 beats per minute in an adult.