premature atrial complex


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premature atrial complex (PAC)

an atrial depolarization that occurs earlier than expected. It is indicated electrocardiographically by an early P′ wave followed by a normal QRS complex. PACs may be the result of atrial enlargement or ischemia or may be caused by stress, caffeine, or nicotine. They may occur occasionally or in a regular pattern. Occasional PACs usually have no significance, but frequent PACs may lead to atrial fibrillation or to paroxysmal supraventricular tachycardia. Also called atrial extrasystole, atrial premature beat, atrial premature complex.

premature atrial complex

Atrial premature contraction, atrial premature depolarization Cardiology A premature heartbeat of atrial origin, and common cause of irregular pulse; PACs arise in normal hearts, but are more common in structurally abnormal hearts, and ↑ with age EKG Premature P wave, P-R interval of > 120 msec Management PACs are rarely serious and do not require therapy