afterdepolarization /-dēpō′lərizā″shən/ , a membrane potential depolarization that follows an action potential. In cardiac muscles, it may be early (during phases 2 and 3 of the action potential) or delayed (during phase 4), and it is thought to cause atrial and ventricular tachycardia, especially in the setting of a long Q-T interval or digitalis poisoning. Also called afterpotential.
