High Quality Content by WIKIPEDIA articles! A premature ventricular contraction (PVC), also known as a premature ventricular complex, ventricular premature contraction (or complex or complexes) (VPC), ventricular premature beat (VPB), or extrasystole, is a relatively common event where the heartbeat is initiated by the heart ventricles rather than by the sinoatrial node, the normal heartbeat initiator. The electrical events of the heart detected by the electrocardiogram allow a PVC to be easily distinguished from a normal heart beat.