Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are among the commonest aortic arch anomalies.
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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
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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
trisomy 21 4, trisomy 18 and other chromosomal defects 7
Clinical presentation
They are often asymptomatic, but ~10% of people may complain of tracheo-oesophageal 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 oesophagus variable 3:
80% posterior to the oesophagus
15% between oesophagus 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 oesophagus 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 oesophagus 5.
Treatment and prognosis
Complications
The presence of an aberrant right subclavian artery poses a substantial risk of life-threatening haemorrhage in patients undergoing surgery like oesophagectomy. 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 oesophagus 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.
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