Interrupted Aortic Arch (IAA)

What is an interrupted aortic arch (IAA)?

An interrupted aortic arch is a very rare congenital heart defect. It occurs when the aorta does not develop normally. The aorta is the large blood vessel that leaves the left ventricle of the heart and delivers oxygen rich blood to the rest of the body.

The part of the aorta leaving the heart is called the ascending aorta as it arises upwards. The aorta then curves left forming the shape of an arch. It then descends towards the lower body and this is called the descending aorta. There are three blood vessels that arise from the aortic arch and these supply the head and arms with oxygen rich blood. 

An interrupted aortic arch is where the portion of the aorta between the ascending and descending aorta has not formed and there is a blockage. This means that oxygen rich blood cannot supply the rest of the body.

There are 3 different types of interrupted aortic arch and they are determined by where the interruption is.

This diagram is of an interrupted aortic arch type II which is the most common type.

How can it be spotted?

An interrupted aortic arch can be detected at the 20-week anatomy scan or after birth by echocardiogram.

During pregnancy, there is a small blood vessel called the ductus arteriosus that allows blood to bypass the lungs and go straight to the descending aorta to supply oxygen rich blood to the body. A couple of days after birth, this vessel usually closes on its own. In a baby with an interrupted aortic arch, when the duct closes, blood can no longer reach the lower body. This can cause the baby to suddenly become very ill. 

If the interrupted aortic arch is not picked up in the antenatal period, once the baby is born and the ductus arteriosus closes the baby will display the following signs:

If an interrupted aortic arch is diagnosed during the pregnancy, plans can be made to give the baby a medicine at birth called prostaglandin which keeps the ductus arteriosus open until the baby can have surgery.

How can it be treated?

Immediate treatment will be gaining intravenous access after birth and the medicine prostaglandin started to keep the duct open. This will enable blood to reach the body until surgery can take place.

Heart surgery will usually be performed in the first few weeks of life once the baby is stable. The aim of the surgery is to connect the two ends of the aorta together. 

Often a baby with an interrupted aortic arch will have a ventricular septal defect (VSD) which is a hole between the two ventricles. During the surgery to reconnect the two ends of the aorta, the VSD will also be closed and the ductus arteriosus will be tied off.

General advice/info for the future

Babies and children with an interrupted aortic arch (even when surgically treated) will need lifelong follow up.

Some children may experience further problems with the aortic arch or the aortic valve and further surgeries or cardiac catheterization may be required when the child is older.

As your baby will have had heart surgery, they will have a scar down the middle of the chest, and there will be small scars where drain tubes were used, but these will fade over time.

Long-term follow-up by the cardiologist to assess growth of the aortic valve region and the reconstructed aortic arch is essential. Reoperation to address further problems with these areas may be needed in 10 to 20 percent of patients.