A right aortic arch usually produces several abnormal shadows on a standard frontal film of the chest. The aortic knob protrudes from the right side of the mediastinum, the trachea is deviated to the left, and the descending aorta can be identified along the right side of the spine. A more conclusive diagnosis can be made from the indentation produced by the arch on the barium-filled esophagus. This also serves to distinguish the two types of right aortic arch. The presence of a large indentation on the posterior aspect of the esophagus is characteristic of the type of arch most frequently associated with a vascular ring. A right arch without a posterior component is commonly associated with significant congenital heart disease.