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

Video Transcription

Okay, we'll go ahead with the answers. The answer is bidirectional right bundle branch block and retrograde AV nodal block. Okay, let's look at the tracing here.  We have right bundle branch block in the baseline state. Here's a HISS. It's a little bit tune up here, a little bit of a long HV interval. And here is a retrograde HISS  during right ventricular pacing. You see it's after the local ventricular electrogram. That's because this is right bundle branch block  and it's bidirectional right bundle branch block. It takes a long time to get down to the right ventricle. And to keep up the HISS-Purkinje system as it normally does,  it comes out the back here and goes up the left bundle. So what we see here is the HISS deflection out the back there, indicative of retrograde right bundle branch block.  So we have anterograde and retrograde. That's bidirectional right bundle branch block. And we see retrograde conduction through system here to the AV node, to the atrium.  And in this case, it gets to the, but not to the atrium. Therefore, there is retrograde block in the AV node. So we have bidirectional right bundle branch block  and block in the AV node.

Video Summary

The video discusses a complex cardiac conduction issue involving bidirectional right bundle branch block and retrograde AV nodal block. The tracing shows a right bundle branch block with a prolonged HV interval in the baseline state. During right ventricular pacing, a retrograde HISS deflection occurs, indicating the block's bidirectional nature as it travels up the left bundle. This retrograde conduction happens up to the AV node, but not to the atrium, confirming a block in the AV node as well. Thus, the case presents both anterograde and retrograde conduction challenges.

Keywords

cardiac conduction

right bundle branch block

retrograde AV nodal block

HV interval

retrograde conduction