A 30-year-old male graduate student was referred because of the sensation of fullness in his throat that appeared to be aggravated by swallowing. The symptom had been present for several years but had become more prominent in the weeks prior to the consultation. He was able to swallow liquids and solids without difficulty. He did not describe typical esophageal reflux or heartburn. Physical examination was normal and screening blood tests were within the reference range. A barium swallow radiograph showed an oblique indentation (white arrow) on the postero-lateral aspect of the proximal thoracic esophagus at the level of the fourth thoracic vertebra (Fig. 1). A subsequent contrast–enhanced computed tomography (CT) scan (Fig. 2) showed an aberrant right subclavian artery (thin arrow) posterior to the esophagus that resulted in esophageal compression (thick arrow). At upper gastrointestinal endoscopy, there was indentation of the esophagus by a pulsatile external vessel at 27 cm from the gingival margin. The diagnosis was that of an aberrant right subclavian artery.

An aberrant right subclavian artery is the most common congenital abnormality of the aortic arch and occurs in approximately 1% of the population. During embryonic development, abnormal involution of the fourth aortic arch allows the right seventh inter-segmental artery to remain attached to an abnormally persistent right dorsal arch forming an aberrant right subclavian artery. The aberrant artery passes posterior to the esophagus in 80% of cases and anterior to the esophagus in the remainder. The anomaly was first reported by Dr David Bayford in 1794 who described it as ‘lusus naturae’ meaning freak of nature. Most patients with an aberrant right subclavian artery are symptom-free throughout their lives. However, a minority develop symptoms such as a recurrent cough, dysphagia, and thoracic pain. Horner's syndrome has also been reported. The differential diagnosis of esophageal compression on a barium swallow radiograph needs to include aortic arch indentation and aortic dissection. The diagnosis of an aberrant right subclavian artery can be readily confirmed by CT scan, magnetic resonance imaging, arteriography and endoscopic ultrasonography. In symptomatic patients, dysphagia can usually be controlled by thorough chewing of food as well as the liberal use of fluids. Rarely, the aberrant vessel is resected and reanastomozed to the ascending aorta. The term dysphagia lusoria reflects the terminology first used by Dr Bayford.

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