During normal aortic arch development, a double arch forms, merging behind the heart to become a single dorsal aorta. The right sided segment disappears, leaving the normal left aortic arch. The normally developed aorta lies in front of the trachea and esophagus. Abnormalities in sequential embryonic development can result in aortic arch malformations. If a double arch persists, the right and left sides of the aorta encircle the trachea and esophagus, and will affect these structures. If the left side of the double arch disappears, a persistent right arch results which lies behind the trachea and esophagus. In the absence of other vascular abnormalities an isolated right aortic arch will not negatively affect on these structures.