(FIT)-Module 4 Workshop 7: Electrocradiogrpahic and Electrophysiological Correlations, Atrial Fibrillation, Clinical Scenarios and Syndromes-Poole Case 1 Answer

Video Transcription

Video Summary

The patient's Holter monitor reveals atrial flutter with a long atrial cycle and QRS widening during exercise, caused by use-dependent sodium channel blockers like flecainide or propafenone. These drugs increase the risk of conduction abnormalities at higher heart rates. This scenario confirms answer B, the blockade of voltage-gated sodium channels, as correct. In contrast, class III antiarrhythmic drugs, which exhibit reverse use dependence and block IKR (answer A), block of L-type calcium channels (answer C), and sodium-potassium ATPase pump inhibition (answer D) are incorrect as they do not match the observed tracings.

Keywords

atrial flutter

QRS widening

use-dependent sodium channel blockers

flecainide

propafenone