Where do premature atrial complexes originate?

Premature atrial complexes (PACs) originate in the atria of the heart. These complexes are characterized by early depolarization of the atrial muscle, which results in an early atrial contraction. The source of this early impulse is often a focus within the atrial tissue, which fires before the next normal impulse from the sinoatrial node (the heart's natural pacemaker). This can disrupt the regular rhythm of the heartbeat, leading to the sensation of palpitations.

Understanding the mechanism of PACs is crucial in distinguishing them from other arrhythmias, such as premature ventricular complexes (PVCs) which arise from the ventricles, or impulses originating from the sinoatrial or atrioventricular nodes. Recognizing where PACs originate can help in diagnosing underlying conditions and determining potential treatment options.