Synonyms: ectopic beats, premature beats, premature atrial or ventricular complexes
Extrasystoles are essentially extra beats, or contractions, which interrupt the normal regular rhythm of the heart. They occur when there is electrical discharge from somewhere in the heart other than the sino-atrial node. They are classified as atrial or ventricular extrasystoles according to their site of origin.
This is a companion discussion topic for the original article at https://patient.info/doctor/cardiovascular-disease/extrasystoles