Hemodynamic Characterization of a Circular Shunt After Arterial Switch in a Neonate to Guide Management Strategy.

A circular shunt is a complex and often critical condition in neonates after cardiac surgery. We report a case of a newborn with refractory hypoxemia and a circular shunt following an arterial switch operation. Cardiac catheterization provided a precise hemodynamic characterization and guided intervention. A trial balloon occlusion confirmed that closure would resolve the shunt, leading to successful device deployment and resolution of the patient's condition. Hemodynamic changes due to inadvertent partial pressure of arterial carbon dioxide (PaCO2) accumulation suggest that, in addition to focusing on inspired oxygen concentrations during shunt calculations, one needs to pay heed to PaCO2 levels as well. This case highlights the indispensable role of catheterization for detailed hemodynamic assessment and guiding interventional strategies when non-invasive imaging is insufficient.