The aim of this study was to describe atrial septal defect morphology in hypoplastic left heart syndrome, to report the incidence of restrictiveness and its relationship with defect morphology, to correlate restriction with midterm outcome, and to describe our interventional approach to restrictive defect.

From 2011 to 2015, 31 neonates with hypoplastic left heart syndrome underwent hybrid procedure with pulmonary artery banding and ductal stenting at our Institution. Restrictive physiology of the atrial septal defect was based on Doppler gradient >6 mmHg through the defect and on clinical signs of pulmonary hypertension. The mean gradient was then measured invasively. Restrictive defect occurred in 11/27 patients (40%). The restrictive group showed three ostium secundum defects (27%) and eight complex morphologies (73%). Conversely, in the non-restrictive group, we observed 11 ostium secundum defects (69%) and five complex morphologies (31%). Early balloon atrioseptostomy was required in three cases. Late restriction occurred in eight patients and was dealt with balloon dilation, stenting, or atrioseptectomy. There was no significant difference between restrictive and non-restrictive groups in terms of early or 12-month survival.

Complex morphologies were more frequently related to restrictiveness. Stenting technique has a crucial role, as the procedure carries a significant risk for stent migration. Effective treatment of restrictive atrial septal defect is related to a better outcome, as it leads to equalisation of survival between patients with and those without restrictive atrial septal defect.