Aberrant right subclavian artery
CTA requested for evaluation of carotid stenosis diagnosed on previous Doppler study.
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Right subclavian artery on this case is the fourth and last aortic arch's branch and hooks back to reach the right side passing posterior to the oesophagus.
Instead of being the first branch (with the right common carotid as the brachiocephalic artery), aberrant right subclavian artery (ARSA) 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