Introduction and objectives: Permanent His-bundle pacing is effective in patients with supra-Hisian atrioventricular block. We report our experience in patients with infra-Hisian atrioventricular block.
Methods: The study involved selected patients referred for syncope and intraventricular conduction disturbance, infra-Hisian atrioventricular block, with left ventricular dyssynchrony and no coronary sinus access. All patients underwent electrophysiological study to evaluate infra-Hisian atrioventricular conduction, both at baseline and after flecainide administration. We selected patients with an indication for permanent pacing in whom His-bundle pacing produced a narrow QRS complex. Leads were implanted in the right atrium, in the bundle of His, and at the apex of the right ventricle, and connected to the atrial, left ventricular, and right ventricular terminals, respectively, of a biventricular pacemaker generator. All pacemakers were programmed in DDD mode with a left ventricle-right ventricle interval of 80 ms.
Results: Between February and December 2004, seven patients met the study's inclusion criteria. The His-bundle lead was implanted successfully in five. The His-bundle pacing threshold remained stable in two patients, whereas it increased in three. During follow-up, at between 2 and 12 months, no lead dislodgement or failure to capture was observed. Echocardiography did not disclose any deterioration in ventricular function, or any worsening of or new valvular incompetence, but showed that ventricular dyssynchrony had disappeared in previously affected patients.
Conclusions: His-bundle pacing is the only pacing mode capable of inducing a physiologically normal ventricular contraction. It can be used in some patients with infra-Hisian atrioventricular block.