abnormal aortic arch and aortic arch branch attachment persistent ductus caroticus 2013-11-15T15:25:58Z MP:0012310 MPheno.ontology csmith persistent carotid duct uni- or bilateral persistence of the segment of dorsal aorta located between the third (III) and fourth (IV) aortic arches, which normally regresses early in development; persistence of ductus caroticus with regression of third arch or fourth arch causes the internal and external carotid arteries to arise from the aortic arch on the left side