What is the principle observation for determining VAERP?

What is the principle observation for determining VAERP?

• A. Longest premature stimulus coupling interval (S1 S2) that fails to conduct retrograde to atrium
• B. Shortest premature stimulus coupling interval (S1 S2) that fails to conduct retrograde to atrium
• C. Longest premature stimulus coupling interval (S1 S2) that conducts retrograde to atrium
• D. Any premature stimulus interval that conducts retrograde to atrium

Answer: (A)

In VAERP assessment, what you’re looking for is the boundary of retrograde conduction after a ventricular extrastimulus. You pace the ventricle with a drive train and then deliver a premature ventricular stimulus (S2) at progressively longer coupling intervals. The principle observation is the longest S1-S2 interval that fails to produce retrograde atrial activation. This interval marks the retrograde effective refractory period—the point at which the pathway is just refractory. Any longer interval would conduct retrogradely, while shorter ones would fail. That’s why the correct description is the longest coupling interval that fails to conduct retrograde to the atrium.

In VAERP assessment, what you’re looking for is the boundary of retrograde conduction after a ventricular extrastimulus. You pace the ventricle with a drive train and then deliver a premature ventricular stimulus (S2) at progressively longer coupling intervals. The principle observation is the longest S1-S2 interval that fails to produce retrograde atrial activation. This interval marks the retrograde effective refractory period—the point at which the pathway is just refractory. Any longer interval would conduct retrogradely, while shorter ones would fail. That’s why the correct description is the longest coupling interval that fails to conduct retrograde to the atrium.