Significance of reverse orientation of the ductus arteriosus in neonates with pulmonary outflow tract obstruction for early intervention.

Reverse orientation of the ductus arteriosus (RDA), defined as an inferior angle at the aortic junction of <90 degrees , is associated with pulmonary atresia; however, the significance of RDA in nonatretic pulmonary outflow tract obstruction (POTO) is unknown. The purpose of this study was to evaluate the relation between ductal morphology and the need for early intervention. Ductal morphology was retrospectively reviewed in 76 neonatal cases of POTO. Patients were stratified to those with conotruncal (CT) or primary pulmonary valve (PV) abnormalities. The prevalence of RDA was 40 of 68 (59%) and was higher in patients with CT defects (28 of 30, 93%) compared with PV abnormalities (12 of 38, 32%; chi-square = 26.4, p <0.0001). Early intervention was required in 29 of 40 patients with RDA (73%) compared with only 8 of 28 patients with normal ductal morphology (31%; chi-square = 12.8, p <0.001). The proportion of patients with RDA who required early intervention was greater in PV abnormalities (12 of 12, 100%) compared with CT defects (17 of 28, 61%; chi-square = 6.5, p <0.02). Importantly, after excluding patients with pulmonary atresia, these analyses were unchanged. In patients with nonatretic POTO, a threshold inferior angle of 65 degrees was predictive of the need for early intervention. RDA in patients with PV abnormalities, or CT defects and an inferior angle <65 degrees , is a specific indicator for early intervention. These findings demonstrate an association between RDA in the context of atretic and nonatretic POTO and the need for early intervention. The need for early intervention should be considered when RDA is identified in this population.