The aorta is the main blood vessel that carries oxygen-rich blood away from the heart to the organs of the body. After it leaves the heart, it first ascends in the chest to give off blood vessels to the arms and head. Then, it turns downward, forming a semicircular arch and heads toward the lower half of the body.
Interrupted aortic arch (IAA) is the absence or discontinuation of a portion of the aortic arch.
There are three types of interrupted aortic arch, and they are classified according to the site of the interruption:
- Type A: The interruption occurs just beyond the left subclavian artery. Approximately 30 percent to 40 percent of the infants with interrupted aortic arch have type A.
- Type B (diagram): The interruption occurs between the left carotid artery and the left subclavian artery. Type B is the most common form of interrupted aortic arch. It accounts for about 53 percent of reported cases.
- Type C: The interruption occurs between the innominate artery and the left carotid artery. Type C is the least common form of interrupted aortic arch, accounting for about 4 percent of reported cases.
Interrupted aortic arch is thought to be a result of faulty development of the aortic arch system during the fifth to seventh week of fetal development. This defect is almost always associated with a large ventricular septal defect (VSD). Patients with interrupted aortic arch (particularly those with type B) often have a chromosomal abnormality called DiGeorge syndrome. In addition to interrupted aortic arch, patients with DiGeorge syndrome may have problems with low calcium, developmental delay and immune system abnormalities.