cardiac arrhythmia [Gk, kardia + a + rhythmos, without rhythm] , 1. (Nontechnical) an abnormal cardiac rate or rhythm. The condition is caused by a failure of the sinus node to maintain its pacemaker function or by a defect in the electrical conduction system. Kinds include bradycardia, ectopic beat, heart block, tachycardia. 2. most accurately, the absence of a cardiac rhythm, as in asystole.
