Paradoxical shortening of QRS interval during right ventricular pacing in patient with complete bundle branch block
Abstract
Authors have tested the hypothesis: DDD pacing from selective site of right ventricle with optimal timing of AV delay and evoked fusion beats can achieve shortening of native QRS interval with the welcome implication of reducing LV dyssynchony during right ventricular pacing. The group of 15 pacients with preserved AV conduction and complete bundle branch block were paced in DDD mode with different AV delay in order to achieve fusion beats.
There were 4 patients excluded because of non obtaining of reliable fusion beats morphology for reason of pacemakers technologicaly inability of fine-tuning AV delay.From the 11 patients in 8 patients (73%) paradoxical shortening of native QRS interval was achieved, in 3 patient the length of QRS was identical. Average duration of QRS complex : paced(V00): 146 ms, native(A00): 137 ms, fusion beats(DDD): 126 ms.