Verapamil-sensitive atrial tachycardia with a slow conduction zone near the noncoronary aortic sinus and His bundle.

This report presents a verapamil-sensitive atrial tachycardia, mid-atrium septum activating the earliest. Concealed entrainment was obtained at noncoronary aortic sinus (NCS), where the local activation was delayed compared to mid-septum. The tachycardia was successfully ablated at NCS. The entrance of the slow conduction zone was located at NCS.