(FIT)-Module 1, Workshop 1: Electrocardiographic/Electrophysiologic Correlation-Tomaselli Case 1 Answer

Video Transcription

Video Summary

The video discusses the effects of dofetilide on cardiac cells. Cells in panel A, exposed to dofetilide, show longer action potentials that lengthen further at slower pacing cycle lengths compared to cells in panel B. Normally, myocardial action potentials lengthen at slower cycle lengths. However, ranolazine and diltiazem shorten action potential duration. Amiodarone shows minimal impact on frequency dependence. Dofetilide, contrastingly, prolongs action potentials with a reverse use-dependent effect due to its influence on the IKR rapid component of the delayed rectifier, leading to more prolonged action potentials at slower pacing rates.

Keywords

dofetilide

cardiac action potentials

IKr channel

reverse use-dependence

antiarrhythmic drugs