CT angiogram revealed a right-sided aortic arch crossing the midline posterior to the esophagus, further descending on the left side (circumflex aorta). The circumflex arch is ectatic and measures 38 mm in its maximum diameter. Marked compression on the posterior aspect of the esophagus by the ectatic circumflex arch is also noted.
The first branch arising from the arch is the left common carotid artery, followed by the right common carotid artery, right subclavian artery, and finally the aberrant left subclavian artery which arises from a small diverticulum after the aortic arch has crossed the midline to the left. A left ductus arteriosus is also present which completes the vascular ring. The thoracic aorta descends on the left side. The diagnosis is consistent with right circumflex aorta with aberrant left subclavian artery.