Right aortic arch with left descent.

A right aortic arch may descend either to the right or left of the spine. When the aorta crosses from right to left posterior to the esophagus, the findings on plain chest film and barium swallow studies may simulate those of a mediastinal mass, especially in older patients. Although aortography is definitive, computed tomography can accurately display the retroesophageal aorta, allowing rapid and hazard free diagnosis.