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Pulmonary atresia is a congenital heart defect where the baby is born with a defective or absent pulmonary valve. The valve should have three leaflets which allow blood to flow forward into the pulmonary artery but prevent it from flowing backward into the right ventricle. For those born with pulmonary atresia, the valve either malfunctions or does not form at all.
A sheet of tissue forms in place of the pulmonary valve, not allowing blood passage into the pulmonary artery. This defect develops in the first 8 weeks of pregnancy and affects the flow of blood from the right ventricle (heart chamber) to the pulmonary artery leading to the lungs. It can be identified in a prenatal ultrasound.
Pulmonary atresia affects 1 in 10,000 live births. Babies born with the condition will begin to exhibit symptoms of the associated defects on the day they are born. Diagnosis and timely surgical intervention is required for the survival of the baby.
There are two different kinds of pulmonary atresia based on whether ventricular septal defect or VSD is present or not. VSD refers to a hole in the heart. The hole is located in the wall that separates the two lower ventricles of the heart.
1. Pulmonary Atresia with an intact Ventrical Septum: Here the atrial septum or wall between the left and right ventricles is developed and intact. However, the flow of blood into the right ventricle during pregnancy is not adequate and the chamber does not develop fully. The small size of the right ventricle causes problems in transporting blood from the heart to the lungs. So the main pulmonary artery stays small and the pulmonary valve does not form.
2. Pulmonary Atresia with a Ventricular Septal Defect: Here the hole in the atrial septum causes blood to intermittently flow into and out from the right ventricle. The right ventricle is not too small and the pulmonary valve forms but it is defective. The small-sized pulmonary valve has trouble directing the flow of blood from the heart. This condition is similar to tetralogy of Fallot.
Ventricular Septal Defect Present
Treatment will start with the administration of prostaglandin E1 medication to keep the ductus arteriosus open post the birth of the baby. The administration of the intravenous medication will ensure that blood circulates through the alternative route in the baby’s heart till surgical intervention takes place.
Heart catheterization may be used to solve the problem of blood flow in the right direction by inserting a thin, flexible tube into the heart. A small balloon may be used to expand the pulmonary valve during this process. A stent may be placed to ensure that the ductus arteriosus stays open till corrective surgery takes place.
During the surgery, a patch may be placed over the ventricular septal defect to close the hole between the left and right ventricles of the heart. The passage to the pulmonary artery may be enlarged to allow better blood flow. The pulmonary valve may be repaired or replaced based on the condition it is in.
Ventricular Septal Defect Absent
A series of three different surgical procedures will be performed on the baby to treat the condition. Starting with re-routing blood flow for the baby immediately after birth and eventually repairing the pulmonary valve when the baby older.
A Blalock- Taussing, otherwise known as BT, shunt is placed to redirect the flow of blood towards the lungs once the ductus arteriosus closes. This is the first surgery to palliate the heart by connecting an artery from the arm to the pulmonary arteries.
The second surgery is known as a Glenn procedure in which the superior vena cava is connected directly to the right lung artery. The superior vena cava is a large vein that carries blood from the upper body into the heart.
The Fontan procedure is the final part of the trio of operations. In this surgery, the inferior vena cava is connected to the right lung artery. The inferior vena cava is the vein that carries oxygen poor blood from the lower parts of the body to the heart.
The outlook is quite positive for a baby who has undergone corrective surgery for pulmonary atresia. Most children recover from the birth defect and will go on to meet all regular developmental milestones. Special attention should be paid to the nutrition and hygiene of the baby post surgery.
Immediately after surgery, the baby will be given a course of preventive antibiotics for possible infections. Parents will be encouraged to ensure that the child stays active and plays. A regulated routine for health care as well as follow ups with the doctor are provided.
Replacement valves and shunts may need to be replaced with larger versions as the child grows older. This will entail more surgeries at a later date.