A Variant of Crossed Pulmonary Arteries in Association with Coarctation of Aorta.

Crossed or "crisscross" pulmonary arteries (CPA) are a result of an anomalous origin and course of both the pulmonary arteries from the main pulmonary trunk in which the left pulmonary artery (PA) ostium usually lies directly superior and to the right PA ostium after which they cross each other and supply their respective lungs. This condition is usually associated with conotruncal malformations and genetic syndromes. We describe a case report of an infant, suspected to have Down syndrome, who was diagnosed with CPA and coarctation of aorta on computed tomography (CT) angiography. Our case is unusual because in our patient the right PA ostium was superior and to the left of the left PA suggesting a variant of CPA that has not been documented before. Three-dimensional (3D) CT reconstruction has shown to improve the understanding of this anomaly and its unique 3D display of various angles may enhance anatomical comprehension of such complex cases.