Diastolic Right-To-Left Shunting PDA In Neonatal Coarctation Is A Sign Of Severe Pulmonary Hypertension

In severe neonatal coarctation, patients require a patent ductus arteriosus (PDA) for systemic perfusion. What may go unrecognized is the importance of differentiating ductal flow in systole versus diastole. Right-to-left ductal flow in systole would be a normal finding in severe coarctation as this is essential for distal systemic perfusion. Right-to-left ductal flow during diastole is abnormal and represents severely elevated pulmonary vascular resistance. This differentiation during diastole and systole is not well described in the literature, as pure right-to-left shunting is rare. We describe two neonates with critical coarctation of the aorta with pure right-to-left ductal flow with evidence of pulmonary hypertensive crisis after repair. Case …