abnormal aortic arch and aortic arch branch attachment abnormal ductus caroticus morphology persistent ductus caroticus MP:0012310 MPheno.ontology 2013-11-15T15:25:58Z 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 csmith persistent carotid duct