Pediatric Left Aortic Arch With Aberrant Right Subclavian Artery Etiology: congenital UGI: posterior indentation on the esophagus Clinical: usually asymptomatic but occasionally can have dysphagia lusora Radiology Cases of Left Aortic Arch With Aberrant Right Subclavian Artery AP (left) and lateral (right) images from an upper GI exam shows a left sided aortic arch and a posterior indentation on the esophagus.