• A PAVM was diagnosed in a critically ill cyanotic neonate. • Echocardiography played a pivotal role in establishing the diagnosis. • Urgent transcatheter device occlusion resulted in immediate hemodynamic stabilization.

Anomalous left common carotid artery is a unique and rare abnormality. Most aortic arch anomalies can be explained by the totipotential aortic arch. Rare anomalies may not fit traditional arch regression models. Echocardiography is key for arch anomaly diagnosis and monitoring. Identification of this very rare anomaly carries significant clinical implications.