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-esophageal 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, distal to the left subclavian artery. It then hooks back to reach the right side with its relationship to the esophagus variable:

80% posterior to esophagus
15% between esophagus and trachea
5% anterior to the trachea
Associations
as can be expected from the embryological development of the artery, 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-esophageal course
it can get compressed between the esophagus and the vertebra
the incidence of stenosis/occlusion in this segment is higher
it can be associated with trisomy 21 5, trisomy 18 and other chromosomal defects
Radiographic features
Fluoroscopy
An upper GI contrast study will demonstrate displacement of the contrast-filled esophagus. 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.



References
Related Radiopaedia articles
Anatomy: Thoracic
thoracic skeleton[+]
muscles of the thorax[+]
spaces of the thorax[+]
thoracic viscera[+]
blood supply of the thorax
arteries
thoracic aorta (development)
ascending aorta[+]
aortic arch
brachiocephalic trunk
common carotid artery
subclavian artery[+]
axillary artery
variant anatomy
right-sided aortic arch
double aortic arch
ductus diverticulum
branching patterns
bovine arch
aberrant right subclavian artery
aortic isthmus[+]
descending aorta[+]
pulmonary trunk[+]
veins[+]
lymphatics[+]
innervation of the thorax[+]