Pulmonary atresia (uh-TREE-zhuh) is one of several heart valve defects that may be found at birth or soon after. In pulmonary atresia, the valve between the heart and lungs (pulmonary valve) is not fully developed, which prevents forward blood flow to the lungs, and your baby doesn't get needed oxygen.

Normally, some blood enters the lungs through other passages within the heart and its arteries. Before your baby is born, it receives blood through a hole between the top chambers of your baby's heart (foramen ovale), and blood is pumped out to the rest of your baby's body.

After birth, the foramen ovale usually closes, but in pulmonary atresia it may stay open. Another temporary opening (ductus arteriosus) may allow some blood flow, but your baby will need medication, procedures or surgery to correct the atresia.

In this heart defect, there is also a hole between the two pumping chambers (ventricular septal defect, or VSD) of your baby's heart.

The pulmonary artery and its branches can be very small or nonexistent. In the latter case, additional arteries arise from the aorta to provide blood flow to the lung (major aortopulmonary collateral arteries, or MAPCAs).

Doctors may use several tests to diagnose pulmonary atresia:

• Pulse oximetry. This simple test measures the amount of oxygen in your baby's blood. Your doctor will attach a small sensor to your baby's hand or foot.
• X-ray. An X-ray shows your baby's doctor the shape and size of your baby's heart and any defects.
• Echocardiogram. In an echocardiogram, sound wave movement reveals the features of your baby's heart. Your doctor might also use an echocardiogram of your abdomen before you deliver your baby (fetal echocardiogram) to diagnose pulmonary atresia.
• Electrocardiogram (ECG). In this test, sensor patches with wires attached (electrodes) measure the electrical impulses given off by your baby's heart. An ECG finds abnormal heart rhythms (arrhythmias or dysrhythmias) and may show other heart damage.
• Cardiac catheterization. In catheterization, the doctor inserts a thin, flexible tube (catheter) into a blood vessel in your baby's groin and guides it to your baby's heart. This test shows your baby's heart structure and the blood pressure and oxygen levels in your baby's heart, pulmonary artery and aorta. The doctor may inject a dye into the catheter to see your baby's arteries more easily under X-ray.
• Cardiac CT scan. This scan of your baby's heart and blood vessels is taken to help understand the anatomy and the presence of MAPCAs, which are these collateral arteries, which will be important for planning the repair.

Medication and several procedures may be needed to treat your baby's pulmonary atresia with ventricular septal defect.

Procedures. Your baby may need one or more procedures to improve heart function and blood flow. There are several treatment pathways depending on the anatomy of the pulmonary arteries and the presence or absence of the MAPCAs.

• Stent placement. Placement of a rigid tube (stent) between the aorta and pulmonary artery (ductus arteriosus) allows blood to flow to your infant's lungs.
• Systemic-to-pulmonary artery shunt. This is a surgical procedure that may be needed in the first few days of life to increase blood flow to the lungs by creation of a connection (shunt) between one of the arteries and the pulmonary artery using a small tube of synthetic material. One example of such procedure is the Blalock-Taussig shunt (BT shunt).

Complete repair

• Neonatal complete repair. If your baby's heart has well-developed pulmonary arteries and no MAPCAs, your baby's surgeon can perform the complete repair in one stage during the neonatal period. This will include closure of the ventricular septal defect and placement of a valve conduit (tube) between the right ventricle and the pulmonary artery.
• One-stage complete repair. In this procedure, your baby's surgeon connects all the MAPCAs together to create new pulmonary arteries and then completes the repair with closure of the VSD and placement of the conduit. This is usually performed between 4 and 6 months of age. This procedure may also be called unifocalization.

Staged repair

• Staged unifocalization. If the MAPCAs are small or have multiple areas of narrowing, they may be connected in stages. This allows the arteries to grow to adequate size prior to the complete repair. The source of blood flow to the lungs will be provided through a small shunt from the aorta to the newly constructed pulmonary arteries. After a few months, your baby's heart will be evaluated with a cardiac catheterization and cardiac CT scan to determine the suitability and timing of the complete repair.
• Catheter interventions for the pulmonary artery branches. This procedure is done to assess the anatomy of your baby's heart and reconstruct pulmonary artery branches and dilate or stent the areas that have narrowing in them.