HRS Board Review 2025 New Courses (Reviewers Copy)-Workshop 1_Electrocardio_Miller_2025

Video Transcription

Okay, the answer is retrograde conduction is absent and block is in the hysperkinesis system. Why is this? Look back at the tracing here.  And we have six complexes of ventricular pacing, all are captured. And we have an independent atrial rhythm here coming along. It's high to low.  And when we see a clear P wave between caresses, it looks like a sinus P wave. So these are all sinus complexes here. There is no retrograde conduction,  no influence of ventricular pacing on atrial activation. Where is the cytoblock? Well, we have this situation here where the AH interval, here's a hys,  is constant all throughout here. If there were penetration through the hysperkinesis system, which there almost always is. So almost always retrograde activation  in the hysperkinesis system, but it blocks in the AV node when there's no retrograde. In this case, this guy's got a very sick hysperkinesis system  and his AH is normal and unperturbed. It's as though he doesn't have ventricular pacing going on here.  If there were retrograde conduction, you would see this AH go out a little bit because of concealment into the AV node. It doesn't even make it to the AV node.  Therefore, conduction block in the retrograde direction is in the hysperkinesis system.  And there's our AH intervals, constant as they are. A very unusual situation, but it is what it is.

Video Summary

The video discusses a case where retrograde conduction is absent and the block occurs in the His-Purkinje system. It observes six ventricular pacing complexes with captured sinus complexes. Despite ventricular pacing, there's an independent atrial rhythm and constant AH intervals with no retrograde influence. Normally, retrograde activation occurs in the His-Purkinje system but is blocked at the AV node. In this case, the lack of change in AH intervals suggests the blockage occurs at the His-Purkinje system, not the AV node, indicating a rare situation where the His-Purkinje system is impaired despite normal AH intervals.

Keywords

retrograde conduction

His-Purkinje system

ventricular pacing

atrial rhythm

AH intervals