Aberrant right subclavian artery

Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are the commonest of the aortic arch anomalies ². 

Epidemiology

The estimated incidence is 0.5-2%.

Clinical presentation

They are often asymptomatic, but around 10% of people may complain of tracheo-oesophageal symptoms, almost always as dysphagia termed dysphagia lusoria ³. 

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, after the left subclavian artery. It then hooks back to reach the right side. Its relationship to the oesophagus is variable:

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

Associations

• as can be expected from embryology, the right recurrent laryngeal nerve is usually non-recurrent (that is, enters 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-oesophageal course:
  • it can get compressed between the oesophagus and the vertebra
  • the incidence of stenosis/occlusion in this segment is higher
• it can be associated with trisomy 21, trisomy 18 and other chromosomal defects.

Radiographic features

Fluoroscopy

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

CT/MRI

CT or MRI now usually accomplishes the definitive diagnosis. Both modalities can demonstrate the aberrant branch arising from the distal left aortic arch and coursing as the right subclavian artery.

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