Osmosis video - Premature atrial contraction

Premature atrial contraction is when the atria contract too early because of depolarization from an ectopic focus. While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, premature atrial contractions occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat. The ECG will show an early and abnormal P-wave, as well as one of three patterns, depending on when the PAC occurs: normal ventricular conduction, aberrant ventricular conduction, or a conduction block.