Unusual Association of Arch Anomalies: Fifth Arch Remnant with Isolated Left Subclavian Artery

We report a rare case of a persistent fifth aortic arch (PFAA) associated with an isolated left subclavian artery (ILSA) in a patient with Tetralogy of Fallot (TOF). We report an 11-month-old female with TOF, in whom cardiac computed tomography revealed a double-lumen aortic arch and nonvisualized origin of the left subclavian artery, consistent with PFAA and ILSA. This case highlights the importance of advanced imaging in identifying complex congenital vascular anomalies.