The aortic arch is described as three segments: proximal, distal and isthmus. The proximal component extends from the takeoff
of the innominate artery to the left common carotid artery. The distal component extends from the left common carotid artery
to take-off of the left subclavian artery. The segment of the aorta connecting the distal aortic arch to the juxtaductal region
of the descending aorta is termed the isthmus. This complex composite of segments introduces a risk of developmental anomalies
in the form of interruptions at the various junction points. Aortic arch interruption is characterized by complete lack of
anatomic continuity between the aortic arch or isthmus and the descending thoracic aorta. In aortic arch atresia, with identical
pathophysiology and hemodynamics, there is anatomic continuity between the two segments, represented by an imperforate fibrous
strand of various lengths.