Barium swallow reveals fixed narrowing of the oesophagus at the level of the aortic arch without mucosal abnormality. The narrowing runs oblique from inferior left to superior right and involves the posterior aspect of the oesophagus. This is consistent with extrinsic compression by a retro-oesophageal aberrant right subclavian artery (superimposed in red) resulting in dysphagia lusoria.