Aberrant Left Subclavian Artery Hypoplasia with Right Aortic Arch as a Cause of Inter-arm Blood Pressure Difference and Subclavian Steal in an Asymptomatic Adult.

A 30-year-old asymptomatic man was evaluated for an inter-arm blood pressure (BP) difference; his left arm BP was 15-20 mmHg lower than that of the right arm. Doppler ultrasonography revealed left subclavian artery occlusion with subclavian steal. Contrast-enhanced CT revealed a right aortic arch and an aberrant left subclavian artery with severe proximal hypoplasia. A right aortic arch with abnormal supra-aortic branching is usually diagnosed perinatally or in infancy because of congenital heart disease or vascular ring symptoms. Although rare in asymptomatic adults, congenital aortic arch anomalies should be considered in patients with right aortic arch and interarm BP differences.