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Background: The ductus arteriosus (DA) is critical in maintaining postnatal circulation in neonates with obstructed systemic circulation (OSC) and pulmonary circulation (OPC). We hypothesized that the size of the DA and aortic isthmus (AoI) undergoes adaptive growth in utero to counteract the hemodynamic challenges in these congenital heart diseases (CHD). Methods: Postnatal echocardiograms of neonates diagnosed prenatally with ductal-dependent CHD who were started on prostaglandins within 24 hours of birth were reviewed. We assessed the cross-sectional area of the aortic valve opening, pulmonary valve opening, AoI, and DA by calculating (diameter)2/body surface area. Neonates were classified into OSC or OPC then subgrouped depending upon the patency of semilunar valves: OSC with and without aortic atresia (OSC-AA and OSC-nAA, respectively) and OPC with and without pulmonary atresia (OPC-PA and OPC-nPA, respectively). Results: Ninety-four cases were studied. The DA in OSC was significantly larger than OPC, and the DA in OSC-AA was significantly larger than OSC-nAA. The size of the AoI was significantly larger in OPC than OSC and larger in OSC-AA than OSC-nAA. Within the OSC-nAA group, there was no significant difference in the size of the DA, AoI, or pulmonary valve opening between those with retrograde flow (RF) at the AoI and without (nRF) except the aortic valve opening was significantly larger in nRF. All groups had comparable cross-sectional areas of systemic output. Conclusions: Our findings suggest that DA and AoI show compensatory growth to maintain critical blood flow to vital organs against primary anatomical abnormalities in ductus-dependent CHD.

Background: The ductus arteriosus (DA) is critical in maintaining postnatal circulation in neonates with obstructed systemic circulation (OSC) and pulmonary circulation (OPC). We hypothesized that the size of the DA and aortic isthmus (AoI) undergoes adaptive growth in utero to counteract the hemodynamic challenges in these congenital heart diseases (CHD).Methods: Postnatal echocardiograms of neonates diagnosed prenatally with ductal-dependent CHD who were started on prostaglandins within 24 hours of birth were reviewed. We assessed the cross-sectional area of the aortic valve opening, pulmonary valve opening, AoI, and DA by calculating (diameter) 2 /body surface area. Neonates were classi ed into OSC or OPC then subgrouped depending upon the patency of semilunar valves: OSC with and without aortic atresia (OSC-AA and OSC-nAA, respectively) and OPC with and without pulmonary atresia (OPC-PA and OPC-nPA, respectively).Results: Ninety-four cases were studied. The DA in OSC was signi cantly larger than OPC, and the DA in OSC-AA was signi cantly larger than OSC-nAA. The size of the AoI was signi cantly larger in OPC than OSC and larger in OSC-AA than OSC-nAA. Within the OSC-nAA group, there was no signi cant difference in the size of the DA, AoI, or pulmonary valve opening between those with retrograde ow (RF) at the AoI and without (nRF) except the aortic valve opening was signi cantly larger in nRF. All groups had comparable cross-sectional areas of systemic output. Conclusions: Our ndings suggest that DA and AoI show compensatory growth to maintain critical blood ow to vital organs against primary anatomical abnormalities in ductus-dependent CHD.