In the early stages of fetal development, two aortic arches come from the heart, ascend upward and then descend behind the heart merging together to become a single aorta. As the heart develops normally, the right-sided arch disappears, leaving the left-sided arch to ascend upward and continue to the descending aorta behind the heart. The normally developed left-sided aorta lies in front of the trachea, or breathing tube, and esophagus, or swallowing tube.
A vascular ring is a defect where the arch vessels encircle the breathing and swallowing tubes.This is caused by abnormal development of the aortic arches. If both arches stay open it is called a double aortic arch. The two arches surround the breathing and swallowing tubes and may cause narrowing or compression of these structures and lead to breathing and/or feeding difficulties. In another form of a vascular ring, the left-sided arch disappears, and the right-sided arch stays open. If this is associated with an abnormal origin of the blood vessel that goes to the left arm and a left-sided ductus arteriosus, a vascular ring is formed.
Surgery can be performed in symptomatic patients to divide part of the aorta or other vascular structures in order to eliminate the compression of the breathing and swallowing tubes. For a double aortic arch, the left arch is typically divided along with the ductal ligament. For a vascular ring formed by a right aortic arch with a left-sided ductal ligament, division of the ductal ligament is performed.
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