Delayed afterdepolarization implies?: (A) Increased intracellular Ca", (B) Excessive catecholamines, (C) Digitalis toxicity, (D) All of the above
Answer is D. Ans. is 'd' i.e., All of the aboveDelayed afterdepolarizations occur in late phase 3 or early phase 4 when the action potential is nearly of fully repolarized.The mechanism is poorly understood; however, this type of arrhythmia is found to be associated with high intracellular Ca++ concentrations as occurs with digitalis toxicity or excessive catecholamine stimulation.The triggered impulse can lead to a series of rapid depolarizations (i.e. a tachyarrhythmia).