Pulmonary atresia

Overview

Pulmonary atresia is a heart defect in which a valve on the right side of the heart, called the pulmonary valve, does not form. Without this valve, blood can't flow from the right side of the heart to the pulmonary artery and on to the lungs to become oxygenated. This isn't a problem before birth because the fetus relies on oxygenated blood from the mother to live, rather than the lungs.

The heart consists of four chambers: the two upper chambers, called atria, where blood enters the heart, and the two lower chambers, called ventricles, where blood is pumped out of the heart. The flow between the chambers is controlled by a set of valves that act as one-way doors.

Normally blood is pumped from the right ventricle through the pulmonary valve and the pulmonary artery to the lungs, where the blood is filled with oxygen. From the lungs, the blood travels back down to the left atrium and left ventricle. The newly oxygenated blood is then pumped through another big blood vessel, called the aorta, to the rest of the body.

While a baby is in the womb, a temporary blood vessel called the patent ductus arteriosus (PDA) is open and connects the pulmonary artery and the aorta.

In pulmonary atresia, because there is no way for blood to leave the right ventricle, blood that enters the right atrium passes across an opening into the left side of the heart, which pumps it into the aorta. The only way that blood can reach the lungs is through the PDA.

Babies with pulmonary atresia have reduced oxygen in their blood, a condition called hypoxia. They often have a small right ventricle as well.

Signs & symptoms

Babies with pulmonary atresia may turn blue, a condition called cyanosis; pulmonary atresia may also be called "blue baby syndrome." Other symptoms include:

• Difficult or rapid breathing
• Lethargy
• Cool sweat

Diagnosis

Blueness is always a sign of a problem. Your baby's doctor may also notice a heart murmur, an extra noise that occurs during the heartbeat. Tests used to diagnose pulmonary atresia include:

• Chest X-ray
• Electrocardiogram (ECG or EKG)
• Echocardiogram
• Catheter procedures to determine pressure and oxygen in the heart

Treatment

Initial treatment is a medication, given intravenously, called prostaglandin E-1 to keep the patent ductus arteriosus (PDA) from closing. This allows blood to flow between the pulmonary artery and aorta, thereby bypassing the valve and heart. But this only works temporarily. Your child may also be placed on a ventilator or oxygen to improve respiration.

Immediate surgery usually is necessary to increase blood flow to the lungs. Surgeons create a passageway by inserting a tiny piece of tubing called a shunt between the pulmonary artery and the aorta to increase flow to the lungs. Later, after the first year of life when the baby's lungs have developed more, a second operation called a Fontan procedure may be performed. It connects the right atrium, where deoxygenated blood collects from the body, directly to the pulmonary artery by creating a channel through or just outside the heart to bypass the undeveloped pulmonary valve.

Long-term treatment may include drugs to control heart rhythm disturbances and antibiotics to prevent infection during other surgery or dental procedures.