Ectopic beat (or cardiac ectopy) is a disturbance of the cardiac
rhythm frequently related to the electrical conduction system of
the heart, in which beats arise from fiber or group of fibers
outside the region in the heart muscle ordinarily responsible
for impulse formation, i.e., the Sinoatrial node. Depending upon
the origins of the ectopic beat within the myocardium, an
ectopic beat can be further classified as either a premature
ventricular contraction or a premature atrial contraction. Some
patients describe this experience as a 'flip' or a 'jolt' in the
chest, while others report dropped or missed beats. Such
extrasystoles are more common during periods of stress or
debility; they may also be triggered by consumption of some food
like alcohol, strong cheese, or chocolate. It is a form of
cardiac arrhythmia in which ectopic foci within either
ventricular or atrial myocardium, or from finer branches of the
electric transduction system, cause additional beats of the
heart. Some medications may worsen the