(FIT)-Module 5 Workshop 9: Arrhythmia Case Studies (Putting It All Together for the Boards)-Ellenbogen Case 7 Answer

Video Transcription

Video Summary

The video explains a mechanism of pause due to Phase IV block in the His-Purkinje system, leading to bradycardia-dependent paroxysmal AV block. A premature atrial contraction (PAC) fails to conduct in a diseased His-Purkinje system, illustrating Phase IV bradycardia. Paroxysmal AV block may occur after a non-conducted PAC due to intra-His block. The Phase IV block exhibits prolonged AV block which is corrected by a junctional escape beat that restores normal conduction. This mechanism includes unidirectional anterograde block but maintains retrograde conduction in the His-Purkinje system.

Keywords

Phase IV block

His-Purkinje system

bradycardia-dependent paroxysmal AV block

premature atrial contraction

junctional escape beat