Pulmonary Atresia

What is pulmonary atresia?

Pulmonary atresia is a congenital heart defect in which the pulmonary valve that allows blood to flow to the lungs is not formed properly. Atresia means the absence or abnormal narrowing of a natural opening in the body.

Normally, blood flows from the right ventricle via the pulmonary valve and into the pulmonary artery to the lungs where it collects oxygen. In this condition, the pulmonary valve is absent or blocked and the pulmonary artery is often underdeveloped and this means that blood cannot reach the lungs. Because the blood can’t get to the lungs through the pulmonary artery, it takes a different route by flowing through the foramen ovale (the natural opening between the atria which is present during pregnancy) into the left ventricle and aorta and then gets to the pulmonary artery by going through the ductus arteriosus. During pregnancy, the ductus arteriosus connects the aorta and the pulmonary artery allowing blood to bypass the lungs and go straight to the descending aorta to supply oxygen rich blood to the body. After birth, the baby will rely on this structure to be able to supply oxygen to the lungs. This condition can be a uni or bi ventricular outcome.

There are two types of pulmonary atresia:

Pulmonary atresia with intact ventricular septum (PA/IVS):

This means there is pulmonary atresia and no VSD. Growth and development of the ventricles is helped by blood flowing through them. When there is no hole in the ventricular septum, the right ventricle receives very little blood flow and remains small and underdeveloped.

PA/IVS could be a single ventricle condition.

Pulmonary atresia with a ventricular septal defect (PA/VSD):

In this type of pulmonary atresia, there is a VSD present. This hole between the ventricles allows some of the blood to flow from the left ventricle into the right ventricle. This blood flow may encourage the right ventricle to grow.

How can pulmonary atresia be spotted?

Pulmonary atresia can be detected at the 20 week anatomy scan or after birth by echocardiogram. This is a condition that can be picked up by oxygen saturation checks before discharge from the maternity hospital. If it is not picked up in the antenatal period, once the baby is born they will display the following signs:

• Bluish skin, lips and nailbeds – with lower than normal oxygen levels – this is known as cyanosis
• Fast breathing
• Difficulty feeding
• Lethargy (sleepy or unresponsive)
• Cool or clammy skin
• Irritability

If pulmonary atresia is diagnosed during the pregnancy, plans can be made to give the baby an intravenous medicine at birth called prostaglandin (‘prostin’) which keeps the ductus arteriosus open until the baby can have an intervention.

In most cases, children with pulmonary atresia require intensive medical and nursing care soon after birth.

How can pulmonary atresia 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 lungs until surgery can take place.

If your baby has PA/VSD then the right ventricle is usually well developed and will be able to pump blood to the lungs. Depending on the baby’s oxygen levels and exact anatomy the surgeons or the cardiologists can intervene. The first intervention could be a ‘shunt’ operation . A shunt (a small tube, like a drinking straw) will be placed directly from the aorta to the pulmonary artery. This ensures that enough blood is flowing to the lungs and increases the oxygen levels so ‘prostin’ is no longer required and baby should be able to go home. The cardiologists may be able to insert a ‘stent’ (a small cage like device) inside the ‘duct’ or into the right ventricular outflow tract (underneath the pulmonary valve)-this does the same job as a shunt. Later on surgery will include closing the ventricular septal defect and the insertion of a tube(conduit) from the right ventricle to the pulmonary artery. This tube allows blood flow through the right ventricle into the pulmonary artery and to the lungs-this tube does not grow and patients will require other interventions as they get older.

If your baby has PA/IVS, then the right ventricle is usually very poorly developed and unable to act as a pumping chamber to deliver blood to the lungs. In some cases, the cardiologist may be able to ‘perforate’ the pulmonary valve and perform a balloon dilatation to encourage flow through the pulmonary valve and into the pulmonary artery and encourage growth and function of the right ventricle. Sometimes this is not possible and a shunt may be needed to direct the blood flow to the lungs. A shunt (a small tube, like a drinking straw) will be placed directly from the aorta to the pulmonary artery. This ensures that enough blood is flowing to the lungs and increases the oxygen levels so ‘prostin’ is no longer required and baby should be able to go home.

This will be followed by several stages of surgery during the first few years of the child’s life to balance and optimise blood flow to the lungs and the body.

Other surgeries may include:

Glenn procedure: The second surgery is usually done when the baby is around 6-12 months of age and the surgeons move the superior vena cava from the heart and attach it to the pulmonary artery so that the blood can collect oxygen from the lungs without having to go through the heart.

Fontan procedure: The third stage of surgery, usually done when the child is 2 – 6 years old. The timing of this surgery is dependent on oxygen levels and the child’s general well-being. This surgery involves a tube being attached from the inferior vena cava to the pulmonary artery, so most of the blood from the body now flows directly to the lungs-the surgeon will normally leave a little hole between the tube and the right atrium-this is called a fenestration. This procedure does not create a normal blood circulation in the body but it does improve the circulation.

General advice/info for the future

Babies and children with pulmonary atresia will need lifelong follow-up.
Whenever tubes are used for repairs, they will always require changing, usually before the 10th birthday and some children may need another intervention during adolescence or adulthood. This tube replacement could be a valve insertion in the catheter lab or possibly another open heart surgery.

They will need repeat tests like echocardiogram, ECG and sometimes cardiac Magnetic Resonance Imaging (MRI) scans. The aim of these tests is to monitor your child’s heart function so that any future heart problems are diagnosed and treated quickly.

As complicated as these conditions are, children are encouraged to be as active as they possibly can be. They are encouraged to live as normal a life as they possibly can. As your baby will have had open 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.

With special thanks to Gill McBurney, Cardiac Liaison Nurse Specialist, for her contribution to this information.

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