In typical orthodromic AVRT, retrograde conduction occurs through which structure?

In typical orthodromic AVRT, retrograde conduction occurs through which structure?

• A. Accessory pathway
• B. AV node
• C. Her-Purkinje
• D. Sinoatrial node

Answer: (A)

In orthodromic AVRT, the retrograde limb of the reentrant circuit is the accessory pathway. The impulse travels antegrade from the atria to the ventricles via the AV node and His-Purkinje system, then returns retrogradely from the ventricles back to the atria through the accessory pathway. This pathway provides a fast route that bypasses the AV node for the reverse direction, which is why retrograde conduction is through the accessory pathway. The other structures listed (AV node in the retrograde direction, His-Purkinje as a retrograde route, or the sinoatrial node) aren’t used for retrograde conduction in this typical pattern.

In orthodromic AVRT, the retrograde limb of the reentrant circuit is the accessory pathway. The impulse travels antegrade from the atria to the ventricles via the AV node and His-Purkinje system, then returns retrogradely from the ventricles back to the atria through the accessory pathway. This pathway provides a fast route that bypasses the AV node for the reverse direction, which is why retrograde conduction is through the accessory pathway. The other structures listed (AV node in the retrograde direction, His-Purkinje as a retrograde route, or the sinoatrial node) aren’t used for retrograde conduction in this typical pattern.