Shortening of intraventricular conduction time with rapid ventricular pacing

BackgroundSupernormal conduction (SNC) of the human ventricular myocardium has been reported, but its mechanism remains controversial.MethodsWe recorded monophasic action potentials during rapid ventricular pacing from the right ventricular endocardium in 24 patients with supraventricular tachyarrhythmias who underwent catheter ablation.ResultsIn 7 of 24 patients, shortening of the QRS duration was observed at a pacing cycle length ≤400 ms and lengthening of the QRS duration was observed in 3.ConclusionsShortening of the QRS duration during rapid ventricular pacing was observed in the patients.