Decompressing vein and bilateral superior venae cavae in a patient with hypoplastic left heart syndrome.

The levoatrial cardinal vein (LACV), first described in 1926, acts as a decompressing vessel for pulmonary venous return in cases of severe left-sided obstruction with an intact or significantly restrictive atrial septum. The LACV and the persistent left superior vena cava (LSVC) are thought to share similar embryologic origins. To challenge this notion, we present a unique case of a neonate with hypoplastic left heart syndrome, cor triatriatum, and a decompressing LACV in the presence of bilateral superior venae cavae.