Interrupted Aortic Arch

Overview

An interrupted aortic arch (IAA) is a severe form of aortic narrowing where one part of the aorta, the main blood vessel that carries oxygen-rich blood away from the heart to the body, is disconnected from the rest of the aorta. As a result, the aortic arch doesn’t look like its usual candy cane appearance. IAA may be classified by where this disconnection exists:

• Type A occurs after the takeoff of the left arm (subclavian) artery.
• Type B occurs between the left head (carotid) artery and left (arm) subclavian artery.
• Type C occurs between the two head (carotid) arteries.

IAA, particularly Type B, may be associated with other cardiac abnormalities such as a small bicuspid aortic valve (when two of the three leaflets of the aortic valve are fused together, resulting in two functional leaflets instead of three), narrowing of the outflow tract below the aortic valve (subaortic stenosis), and ventricular septal defect (VSD). Sometimes, IAA is associated with genetic abnormalities such as DiGeorge syndrome (deletion in the 22nd chromosome).

Symptoms

Typically, the narrowed segment occurs where the ductus arteriosus connects to the aorta. The ductus arteriosus is a blood vessel that's present in all newborns. It should shrink and eventually close within the first few days of life. In some cases, the narrowing of the ductus causes the main aorta to also narrow where some of this ductal tissue has extended to the aorta, creating a coarctation. If this occurs, newborn babies can become sick. They have feeding problems, fussiness, sweating, paleness, and difficulty breathing. Also, it becomes difficult to feel pulses on the baby.

Since IAA is a problem of the midline of the chest and neck (conotruncal defect), other structures may be affected such as the palate of the mouth, parathyroid glands, and thymus gland. The roof of the mouth (palate) may not be completely formed, resulting in a cleft. This may result in feeding difficulties due to uncoordinated swallowing and reflux of milk into the nasal cavities. Due to incomplete development of the parathyroid glands, some patients with IAA may have associated problems with calcium metabolism, resulting in abnormally low levels in the blood, which may lead to seizures. If the thymus gland is absent or abnormal, these patients may have problems with their immune systems, resulting in a reduced ability to fight infections.

Progression and complications

If the ductus arteriosus closes in these babies, they will develop shock and die.

Treatment

If IAA is diagnosed in a baby, an intravenous prostaglandin E1 (PGE1) infusion is started to keep the ductus arteriosus open. IAA requires surgical repair, though there’s been some instances where a short segment interruption has been opened in the catheterization lab with angioplasty and stents. If IAA is associated with additional cardiac abnormalities, staged separated surgeries may be necessary. If there’s renarrowing of the aorta after surgical repair, balloon angioplasty or stenting may be options.