Which description best defines AVNERP appearance on an EPS?

• A. Where pacing causes a His signal and captures the paced chamber.
• B. Where pacing does not cause a His signal, but still captures the paced chamber.
• C. Where pacing fails to capture the chamber.
• D. Where pacing results in retrograde conduction.

Answer: (B)

AVNERP appearance is about capturing the paced chamber without engaging the His bundle. When the pacing stimulus lands in tissue that is excitable at that moment but the AV conduction system (especially the His bundle) is refractory or blocked, you can still see a clear capture of the targeted chamber, yet there is no corresponding His electrogram. This specific pattern—no His signal despite chamber capture—is what AVNERP describes.

That’s why the description where pacing does not produce a His signal but still captures the paced chamber is the best fit. It captures the idea of direct local capture without His activation, distinguishing it from situations where a His signal is present (normal or intact conduction) or where there’s no capture at all (failure to pace). Retrograde conduction would show activation in the opposite chamber, which isn’t implied by AVNERP.