Which interval is defined as the longest S1 S2 interval that fails to result in ventricular depolarization?

Which interval is defined as the longest S1 S2 interval that fails to result in ventricular depolarization?

• A. AVERP
• B. VERP
• C. AERP
• D. VAERP

Answer: (A)

The key idea is ventricular refractoriness as measured with extrastimulus testing. You first deliver a train of beats to establish a stable ventricular state, then introduce a premature stimulus (S2) at progressively shorter S1–S2 intervals. The longest interval at which this premature stimulus still fails to produce a ventricular depolarization is the ventricular effective refractory period. This interval marks the end of the tissue’s refractory state and, when shorter, indicates the ventricle is capable of conduction. Understanding VERP helps assess arrhythmia susceptibility and guides pacing and ablation strategies.

The key idea is ventricular refractoriness as measured with extrastimulus testing. You first deliver a train of beats to establish a stable ventricular state, then introduce a premature stimulus (S2) at progressively shorter S1–S2 intervals. The longest interval at which this premature stimulus still fails to produce a ventricular depolarization is the ventricular effective refractory period. This interval marks the end of the tissue’s refractory state and, when shorter, indicates the ventricle is capable of conduction. Understanding VERP helps assess arrhythmia susceptibility and guides pacing and ablation strategies.