What are the differences between pre-atrial contractions, pre-ventricular contractions, and ectoptic beats?

Extrasystoles: There are basically two types of extra beats. Ventricular extra beats and supraventricular extra beats are the two types. They are abbreviated pvcs and apcs for premature ventricular contractions and atrial premature contractions. They are the commonest arrhythmias and are usually benign though they often cause symptoms of annoyance.