Before birth, while the baby is developing, this condition does not threaten life because the placenta provides oxygen for the baby and the lungs are not yet functioning. Blood entering the right side of the fetal heart passes through an opening called the foramen ovale that allows oxygen-rich (red) blood to pass through to the left side of the heart and circulate throughout the body. After birth, the placenta no longer provides oxygen for the newborn — the lungs must provide it.
Two connections within a newborn’s heart can provide temporary help in getting blood flow to the lungs — the foramen ovale and the patent ductus arteriosus (PDA). As these connections spontaneously begin to close after birth, the baby becomes critically ill due to an inadequate blood flow to the lungs where the blood picks up oxygen. This situation cannot support life, since oxygen-poor (blue) blood cannot meet the body’s demands. The baby becomes very blue (cyanotic) and sick.
The diagnosis is usually made shortly after birth. A physician may suspect pulmonary atresia when examining the patient, but generally more testing is necessary to confirm a diagnosis. An echocardiogram (ultrasound of the heart) can show the heart defect, and additional tests may be needed, including cardiac catheterization, electrocardiogram (ECG) and X-rays.
Babies who have PA/IVS need immediate attention in a medical center experienced in treating this condition. Upon diagnosis, the baby is admitted to an intensive care unit. The baby may be treated with oxygen, a ventilator to assist breathing and intravenous medications to help the heart and lungs function more efficiently. In addition, the drug prostaglandin is administered to prevent the ductus arteriosus from closing, thereby maintaining blood flow to the lungs. This helps stabilize the baby while subsequent treatment decisions are made. Once stabilized, there are four surgical treatment options:
Cardiac Catheterization – This procedure can be used as an initial treatment and a diagnostic tool for some cases of PA/IVS. A cardiac catheterization usually will be performed to evaluate any heart defects, establish whether the foramen ovale or ductus arteriosus are still open, and determine the amount and proportions of oxygen-rich (red) and oxygen-poor (blue) blood.
Balloon Atrial Septostomy – This procedure may be performed as part of the cardiac catheterization to improve the proportions of red blood and blue blood between the right and left atria (upper chambers of the heart). A special catheter (tube) with a balloon in the tip is used to create an opening in the atrial septum (the wall between the left and right atria). The catheter is guided through the foramen ovale and into the left atrium, and the balloon is inflated.
Open-Heart Surgery – This procedure is required within the first week of life. It is designed to open the pulmonary valve, allowing blood to flow through the valve and to the lungs. Alternatively, the surgeon may perform a heart valve replacement, replacing the baby’s closed valve with a donor valve. Following surgery, the baby’s circulation may be normal. However, some patients may need another heart valve replacement surgery within the next 10 years as the new valve slowly wears out. The right-sided pumping chamber (ventricle) is typically smaller than normal, so the baby may require another mechanism for blood flow to reach the lungs so enough oxygen can get to the body. In such a case, an artificial connection (shunt) between the aorta — the large artery that leaves the heart and provides oxygen-rich blood to the body — and the pulmonary artery is created to deliver blood to the lungs.
Additional Heart Surgery – Additional surgery is needed when the child is older, particularly in cases where the right ventricle was very underdeveloped. The kind of surgery recommended depends on the size of the right ventricle and the pulmonary artery. If they are normal size and the right ventricle is able to pump blood, open-heart surgery will make blood flow through the heart in a normal pattern. If the right ventricle is small and unable to pump, doctors may perform an operation called the Fontan procedure, in which the right atrium is connected directly to the pulmonary artery.
Follow Up
Children who have PA/IVS require intensive monitoring both before and after surgery, including blood tests, X-rays and urine tests. The child will also need lifelong monitoring by a congenital heart specialist.
Patients born with PA/IVS have a risk of developing endocarditis, an infection in the heart’s walls or valves. Consequently, they require antibiotics before dental work and certain surgeries to prevent endocarditis.
Source: The Mayo Clinic