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One of a group of vascular ring anomalies of the aortic arch. Aberrant right subclavian artery is the most common of the incomplete vascular rings. Its true prevalence is unknown as it may be asymptomatic, however it accounts for about 20% of all vascular rings. Vascular rings may be complete, encircling the entire esophagus and trachea, or incomplete. The two most common complete vascular rings are the double aortic arch and right aortic arch with left ligamentum arteriosum. These structures completely encircle the trachea and esophagus. Incomplete vascular rings may compress either the trachea or esophagus without encircling them. The most common incomplete rings are aberrant right subclavian artery, anomalous innominate artery, and anomalous left pulmonary artery.
Vascular rings result when one of the six embryologic branchial arches fails to regress completely or does so abnormally. In normal development, the distal segment of the right fourth arch involutes and the proximal segment becomes the right subclavian artery. An aberrant right subclavian is formed when the proximal portion of the right fourth arch involutes. Therefore the first brachiocephalic branch off the aorta is the right common carotid, and the right subclavian arises from the descending aorta. It then courses to the right and posterior to the esophagus. An aberrant right subclavian artery is not commonly associated with other congenital abnormalities, but can be seen with Tetralogy of Fallot with left aortic arch, coarctation of the aorta, and interrupted aortic arch.
The majority of patients who become symptomatic present in infancy with feeding or breathing problems, however some may present later in life or remain asymptomatic. Aberrant right subclavian is often an incidental finding during the evaluation of dysphagia but is not commonly responsible for dysphagia.