Which interval is most directly used to assess AV nodal conduction?

Which interval is most directly used to assess AV nodal conduction?

• A. AH interval
• B. HV interval
• C. PR interval
• D. QRS duration

Answer: (A)

AV nodal conduction time is reflected by the AH interval. This interval measures the delay from atrial activation to the His bundle, isolating the conduction happening specifically within the AV node. In electrophysiology, placing electrodes in the high right atrium and at the His bundle shows this atrioventricular delay directly. The PR interval on a surface ECG includes AV nodal conduction but also the time for atrial activation to occur before the AV node, so it’s influenced by multiple factors and isn’t a pure measure of AV nodal delay. The HV interval gauges conduction from the His bundle to the ventricles, i.e., the distal conduction system beyond the AV node. QRS duration reflects how long ventricular depolarization lasts, not AV nodal conduction. Therefore, the AH interval is the most direct indicator of AV nodal conduction.

AV nodal conduction time is reflected by the AH interval. This interval measures the delay from atrial activation to the His bundle, isolating the conduction happening specifically within the AV node. In electrophysiology, placing electrodes in the high right atrium and at the His bundle shows this atrioventricular delay directly.

The PR interval on a surface ECG includes AV nodal conduction but also the time for atrial activation to occur before the AV node, so it’s influenced by multiple factors and isn’t a pure measure of AV nodal delay. The HV interval gauges conduction from the His bundle to the ventricles, i.e., the distal conduction system beyond the AV node. QRS duration reflects how long ventricular depolarization lasts, not AV nodal conduction. Therefore, the AH interval is the most direct indicator of AV nodal conduction.