Wenckebach During Supraventricular Tachycardia

Abstract

In case 1, a 71-year-old man with a history of coronary artery disease presented with recurrent paroxysmal supraventricular tachycardia (SVT) despite treatment with β-blockers. During electrophysiology study, the baseline sinus cycle length was 895 ms, atrial-His (AH) interval was 120 ms, and His-ventricular interval was 60 ms. A narrow complex SVT with tachycardia cycle length of 480 ms was initiated with atrial overdrive pacing at 400 ms, as well as with single atrial extrastimuli. The tachycardia showed a long RP interval with regular concentric atrial activation pattern and atrioventricular Wenckebach conduction (Figure 1). Ventricular overdrive pacing during tachycardia repeatedly terminated the tachycardia without activation of the atrium (Figure 2). Figure 1. Inducible SVT with Wenckebach block above the His (arrows) in patient 1 (ECG leads I, III, V1, and V6). His d indicates distal His; His p, proximal His; CS 1,2, distal coronary sinus; CS 7,8, proximal coronary sinus; and RVa, right ventricular apex. Figure 2. Ventricular overdrive pacing terminates tachycardia with ventriculoatrial block (arrow) (ECG leads I, III, V1, and V6 …