Aberrant right subclavian artery

Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are among the commonest aortic arch anomalies. 

Epidemiology

The estimated incidence is 0.5-2% ¹.

Associations

• as can be expected from the embryological development of the artery, the right recurrent laryngeal nerve is usually non-recurrent, entering the larynx directly.
• aneurysmal dilatation (aberrant subclavian arterial aneurysms) of the proximal portion of an aberrant right subclavian artery can occur, a pouch-like aneurysmal dilatation is called a diverticulum of Kommerell
• if there is a retro-esophageal course
  • it can get compressed between the esophagus and the vertebra
  • the incidence of stenosis/occlusion in this segment is higher
• trisomy 21 ⁴, trisomy 18 and other chromosomal defects ⁷

Clinical presentation

They are often asymptomatic, but ~10% of people may complain of tracheo-esophageal symptoms, almost always as dysphagia, termed dysphagia lusoria ².

Pathology

Course

Instead of being the first branch (with the right common carotid as the brachiocephalic artery), it arises on its own as the fourth branch, distal to the left subclavian artery. It then hooks back to reach the right side with its relationship to the esophagus variable ³:

• 80% posterior to the esophagus
• 15% between esophagus and trachea
• 5% anterior to the trachea

Radiographic features

Plain radiograph

Lateral radiographs of the chest may show obliteration of the retrotracheal space.

Fluoroscopy

An upper GI contrast study will demonstrate displacement of the contrast-filled esophagus ⁵. This displacement by the aberrant vessels produces the so-called bayonet deformity of the aberrant right subclavian artery.

CT/MRI

CT and MRI both demonstrate the aberrant branch arising from the distal left aortic arch and coursing rightwards and can define the relationship between the aberrant artery and the trachea and esophagus ⁵.

Treatment and prognosis

Complications

The presence of an aberrant right subclavian artery poses a substantial risk of life-threatening hemorrhage in patients undergoing surgery like esophagectomy. Moreover, the recurrent laryngeal nerve does not follow the orthodox course, which is important in thyroid and parathyroid surgeries ⁶.

History and etymology

The word lusoria comes from the Latin phrase "lusus naturae", meaning "freak of nature", which refers to the anomalous course of the artery ^8-10.

The term "dysphagia lusoria" was coined by the English surgeon, David Bayford (1739-90) when he described the case of a female patient with "obstructed deglutition" due to an anomalous subclavian artery. The term "arteria lusoria" was later derived from "dysphagia lusoria". 

Bayford, whilst still an apprentice surgeon, attended the patient's autopsy in 1761, at which he found the anomalous arterial course ^8-10. In his described case the artery passed between the trachea and esophagus which is the second commonest course. Yet he did not publish the findings until 28 years later in an oral presentation in 1787, and it was only published in written form in 1789 ¹⁰! Thereafter, for many years the condition was also known as Bayford syndrome ⁹.