High incidence of ductal closure or narrowing at birth in patients with right ventricular outflow tract obstruction with normal orientation of the ductus arteriosus.

Background: Ductal patency is mandatory to manage patients with ductal-dependent pulmonary circulation. The aim of this study is to elucidate the morphological and haemodynamic features of ductus arteriosus with right ventricular outflow tract obstruction, and investigate the appropriate perinatal management. Patients and methods: Patients with prenatal diagnosis of right ventricular outflow tract obstruction at our institution between 2010 and 2015 were included in the study. Reverse orientation of the ductus arteriosus is defined as an inferior angle of <90 degrees at the aortic junction, and normal orientation of the ductus arteriosus as an angle of >90 degrees. We retrospectively reviewed the shape and flow pattern of ductus arteriosus and the clinical characteristics of the cases. Results: A total of 39 patients were enrolled. The shape was divided into normal orientation (n = 15) and reverse orientation (n = 24) of the ductus arteriosus. There was no significant difference in the type of oxygen saturation at birth and age at shunt operation between both the groups. However, the median narrowest diameter of ductus arteriosus in the normal orientation group was significantly smaller than that in the reverse orientation group (2.0 [1.0-5.4] versus 3.0 [1.3-4.4]mm, p <0.05). In two patients of the normal orientation group, ductus arteriosus had dosed at birth, and one of whom died because of severe cyanosis. Conclusions: Normal orientation pattern might have high incidence of an early narrowing or closure of ductus arteriosus at birth. The critical patients need careful evaluation by repeated foetal echocardiography and further maternal interventions.