Generation of aberrant impulses in ectopic areas of heart outside of normal cardiac pacemaker cells results in premature contraction. These impulses interfere with the function of the sinoatrial, or SA, node, which becomes refractory as a compensatory mechanism and skips a beat to restore normal cardiac rhythm, according to LearnTheHeart.com.
A compensatory pause is a skipped heartbeat. It is associated with irregular and premature contractions, which can either originate in portions of the atria, or upper chambers of the heart, or ventricles, the lower chambers of the heart. The ECG Learning Center explains that when they originate in the atria, they are called PACs, or premature atrial contractions. In the latter case, they are associated with PVCs, or premature ventricular complexes. Compensatory pauses associated with PACs are usually incomplete, because they enter the normal cardiac pacemaker, which resets it and results in the earlier firing of the next impulse from SA node. However, the compensatory pause associated with PVCs are complete and the impulse rate of the normal pacemaker cells remains unaltered.