HRS Board Review 2025 New Courses (Reviewers Copy)-Workshop 1_Tomaselli_2025

Video Transcription

The correct answer is D, calcium release from intracellular stores. The observation here are delayed after depolarization, some of which are of sufficient amplitude to generate  another action potential so-called triggered action potential, in this case, a series of triggered action potentials. DADs are generally associated with  intracellular calcium overload and leaky ryanodine receptors. Rapid rates, catecholamines, and digitalis can predispose to delayed after depolarizations. In contrast, EADs are  associated with action potential duration prolongation, a pause-dependent onset, and reactivation of cell surface, sodium, and calcium currents.  These are associated with polymorphic PT and torsade deployment. Again, the best answer here is calcium release from intracellular calcium stores.

Video Summary

The correct answer is D, calcium release from intracellular stores, linked to delayed after depolarizations (DADs). DADs arise from intracellular calcium overload and leaky ryanodine receptors, with conditions like rapid rates, catecholamines, and digitalis increasing their likelihood. Unlike early after depolarizations (EADs), which relate to prolonged action potential duration and involve sodium and calcium current reactivation, DADs lead to triggered action potentials due to elevated calcium levels. EADs occur with pause-dependent onset and are associated with polymorphic ventricular tachycardia and torsades de pointes. Therefore, calcium release from intracellular stores is the most accurate answer.

Keywords

calcium release

delayed after depolarizations

intracellular calcium overload

ryanodine receptors

triggered action potentials