Fetal hemodymanic effects on ductus arteriosus development and influences on postnatal management in infants with ductal-dependent pulmonary blood flow.

The ductus arteriosus (DA) has been studied since Galen. Initially after birth in neonates with obstruction to pulmonary blood flow, DA patency is integral to ensure output and oxygenation. While DA stenting dates back 25 years, there is emerging interest in better understanding how and when to utilize this strategy as an alternative to surgical shunt placement or ongoing prostaglandin administration. Understanding the normal fetal circulation and the perturbations that affect flow and oxygenation is integral to comprehending how normal DA anatomy and morphology may change and how this may influence technical and clinical considerations. In the normal human fetus the great majority of descending aorta circulation comes from the DA, whereas this is a small minority in pulmonary outflow lesions, resulting in size and angle abnormalities. Study of the DA morphology has previously sought to identify patients requiring early intervention and more novel classifications are contributing to knowledge of complications and increasing the likelihood of success. As well, optimal patient selection for aorto-pulmonary shunt vs DA stent remains unclear. This review seeks to convey how fetal circulation can affect the DA, how other clinical considerations such as neurocognitive development support these finding and influence management, and emphasize that the variability in the DA will affect suitability for stenting, which requires further study as guidelines and standards are developed.