In AVRT, which pathway shows HIS earliest activation?

In AVRT, which pathway shows HIS earliest activation?

• A. Left lateral pathways
• B. Septal pathways
• C. Right lateral pathways
• D. Posterior wall

Answer: (B)

During AVRT, the timing of His bundle activation tracks how close the accessory pathway is to the AV node/His system. Septal pathways lie on the interventricular septum right near the AV node and His bundle, so the retrograde impulse traveling through the accessory pathway reaches the atrium in proximity to the His region and makes the His bundle activate earliest. Lateral and posterior pathways are farther from the His bundle, leading to later activation timings. So the pathway that shows the earliest His activation is the septal one.

During AVRT, the timing of His bundle activation tracks how close the accessory pathway is to the AV node/His system. Septal pathways lie on the interventricular septum right near the AV node and His bundle, so the retrograde impulse traveling through the accessory pathway reaches the atrium in proximity to the His region and makes the His bundle activate earliest. Lateral and posterior pathways are farther from the His bundle, leading to later activation timings. So the pathway that shows the earliest His activation is the septal one.