A right-to-left or bidirectional ductal shunt in preterm neonates: grave implication?

We delineate the natural history of a right-to-left or bidirectional (RL/BD) patent ductus arteriosus (PDA) in preterm infants and compare outcomes of an RL/BD and a left-to-right (LR) ductal shunt. We performed a retrospective chart review of preterm infants (< 32 weeks), who, between 2 and 30 days of age, had an RL/BD PDA > 1.5 mm (study group; N = 74) or an LR PDA (N = 87) on echocardiogram (ECHO). In the study group, 27% of infants who were of significantly lower gestational age and birth weight had a "prolonged" RL/BD PDA on two or more ECHOs. Infants with RL/BD PDA required significantly greater surfactant (98.6% versus 94.2%) and less PDA therapy (27% versus 92%) and had higher mortality (48.6% versus 21.8%) compared with those with LR PDA. On regression analysis, lower gestation (odds ratio [OR] 1.45; 95% confidence interval [CI]: 1.15 to 1.83) and RL/BD PDA (OR 4.74; 95% CI: 2.18 to 10.3) were significantly associated with mortality. The independent association between an RL/BD PDA shunt and mortality warrants further investigation. Insights into the etiology of pulmonary hypertension may optimize outcomes in this population.