Which statement about antidromic AVRT is true?

Which statement about antidromic AVRT is true?

• A. Antegrade conduction via accessory pathway and retrograde via AV node
• B. Antegrade conduction via AV node and retrograde via accessory pathway
• C. Both directions via AV node
• D. Both directions via accessory pathway

Answer: (A)

In antidromic AVRT, the reentrant circuit uses the accessory pathway for antegrade conduction from the atria to the ventricles, and the normal AV node for retrograde conduction from the ventricles back to the atria. This means the ventricles are activated first by the bypass tract, often producing a wide QRS because the conduction doesn’t go through the His-Purkinje system. The retrograde limb through the AV node completes the loop to sustain the tachycardia. The opposite arrangement—antegrade through the AV node and retrograde through the accessory pathway—describes orthodromic AVRT, which typically yields a narrow QRS.

In antidromic AVRT, the reentrant circuit uses the accessory pathway for antegrade conduction from the atria to the ventricles, and the normal AV node for retrograde conduction from the ventricles back to the atria. This means the ventricles are activated first by the bypass tract, often producing a wide QRS because the conduction doesn’t go through the His-Purkinje system. The retrograde limb through the AV node completes the loop to sustain the tachycardia. The opposite arrangement—antegrade through the AV node and retrograde through the accessory pathway—describes orthodromic AVRT, which typically yields a narrow QRS.