Which interval is measured from the onset of atrial depolarization to the His bundle?

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

Answer: (B)

The AH interval is the time from the start of atrial depolarization to the His bundle, reflecting conduction through the AV node. This makes it the best answer because it directly measures how long it takes for the impulse to travel from the atria into the AV nodal His region.

Remember how the other intervals differ: the HV interval runs from the His bundle to the onset of ventricular depolarization, outlining conduction through the His-Purkinje system; the QRS duration is the time for ventricular depolarization; the PR interval spans from the start of the P wave to the start of the QRS, encompassing both AV nodal conduction (AH) and conduction from the His to the ventricles (HV).