n. any deviation from the normal rhythm (sinus rhythm) of the heart. Arrhythmias result from a disturbance of the generation or the conduction of electrical impulses from the *sinoatrial node and may be intermittent or continuous. They are subdivided into tachyarrhythmias (fast rate) and bradyarrhythmias (slow rate). They include *ectopic beats (extrasystoles), *re-entry tachycardia, ectopic tachycardias (see supraventricular tachycardia; ventricular tachycardia), atrial and ventricular *fibrillation, and *heart block (which is often associated with slow heart rates). Symptoms include palpitations, breathlessness, and chest pain. In more serious arrhythmias the *Stokes-Adams syndrome or *cardiac arrest may occur. Arrhythmias may result from most heart diseases but they also occur without apparent cause.... arrhythmia
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