AVNERP is defined as which of the following?

• A. The longest retrograde conduction interval that fails to conduct to the atrium
• B. The shortest retrograde conduction interval that conducts to the atrium
• C. The retrograde conduction time from atrial pacing to AV node conduction
• D. The time from atrial activation to ventricular activation during antegrade conduction

Answer: (A)

AVNERP represents the AV node’s retrograde refractory property. It’s the longest ventriculoatrial conduction interval that fails to reach the atrium because the AV node is still refractory in the retrograde direction. In practice, during an EP study you pace the ventricle and look for whether an atrial activation occurs. The longest interval at which retrograde conduction fails defines the AV nodal effective refractory period for retrograde conduction. This value helps gauge how likely retrograde conduction is during tachyarrhythmias and influences the potential for reentry circuits.