Invasive measurements of atrioventricular conduction parameters prior to and following ventricular septal defect closure with the amplatzer device

Because of anatomical proximity, closure of paramembranous ventricular septal defect (pm-VSD) with an Amplatzer occluder has the potential to affect the atrioventricular (AV) conduction system. Electrophysiology studies (EPS) were performed prior to and following closure of the pm-VSD in 19 children aged 8.9 +/- 4.5 years. Data from electrocardiograms, Holter monitoring and exercise tests before intervention and at follow up (1.9 +/- 0.8 years) were reviewed. There were no EPS catheter-induced complications. Incidence of total conduction anomalies was 31.6% with 21% of patients having permanent conduction anomalies. Complete AV block was not recorded in any subject and transitory 1st-degree AV block occurred in 2 patients. Permanent complete right bundle branch block was observed in 2 patients and incomplete right bundle branch block in 2 others. Prolongation in EPS parameters was significant for His ventricle interval (p = 0.017). Otherwise, EPS parameters with increased measurements > 15% were observed in 18 patients (95%). Prolongation of retrograde Wenckebach cycle length was predictive of new onset conduction abnormalities (p = 0.003). Other parameters changes did not correlate with the observed conduction disturbances however. With respect to device implantation characteristics, a large Amplatzer device was the only predictive risk factor for new conduction abnormalities (p = 0.03). Closure of pm-VSD with an Amplatzer device promotes relative changes of the AV conduction system, mainly with large devices. In our limited series, these changes have no apparent clinical impact in the immediate and intermediate terms.