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a premature cardiac contraction that is independent of the normal rhythm and arises in response to an impulse outside the sinoatrial node.
atrial extrasystole one in which the stimulus is thought to arise in the atrium elsewhere than at the sinoatrial node.
atrioventricular extrasystole one in which the stimulus is thought to arise in the atrioventricular node.
interpolated extrasystole a contraction taking place between two normal heartbeats.
nodal extrasystole atrioventricular extrasystole.
retrograde extrasystole a premature ventricular contraction followed by a premature atrial contraction, due to transmission of the stimulus backward, usually over the bundle of His.
ventricular extrasystole one in which either a pacemaker or a re-entry site is in the ventricular structure.
Extrasystole occurring as a result of an impulse originating in the atrioventricular node. Synonym: junctional extrasystole
See also: extrasystole