Coexistence of complete infra-Hisian block, WPW syndrome and Mobitz type II Kent Bundle block

A 65-year-old patient with a chief complaint of syncope had an ECG with ventricular preexcitation and intermittent second-degree atrioventricular (AV) block. AV conduction was maintained by the accessory pathway only, with no evidence of AV nodal conduction. Electrophysiological study demonstrated that the QRS duration and morphology did not increase with atrial pacing; however, A-H prolongation occurred with increased pacing rates.