Double ventricular response in dual AV nodal pathways mimicking supraventricular as well as ventricular tachycardia

Supraventricular tachycardias confined to the AV junction are usually thought to be due to reentry using a slow and a fast conducting pathway. In the case presented, a marked difference of conduction velocity in dual AV nodal pathways and retrograde block in the slow conducting pathway caused a ventricular double response to a single atrial depolarization. At a critical heart rate this phenomenon occurred in a bigeminal fashion, mimicking supraventricular as well as ventricular tachycardia.