Pulmonary atresia is caused by the abnormal formation of the pulmonary valve, which is responsible for allowing blood flow out of the heart to go to the lungs. The blood flow in that area is obstructed with an excessive tissue lining that causes the valve to be unable to open or close completely. Less blood to the lungs means less oxygen supply in the body.
In general, this congenital heart disease is fatal and can be diagnosed from the time the baby is born. Among babies, there are other natural cardiac channels that allow an amount of blood to flow to the lungs. Although these channels are important for babies when they are still in the womb, they generally close right after birth.
As pulmonary atresia restricts delivery of enough oxygen in the body, the disease mostly causes babies to have blue-colored skin (cyanosis) and treatment is needed, including medications and/or surgery, to improve the heart function.
Pulmonary atresia tends to be symptomatic among babies right after birth. Signs and symptoms of the disease include:
- Cyanosis, which makes the skin turn gray or blue
- Difficulty breathing
- Fatigue or loss of energy
- Feeding problems
In most cases, a doctor can detect pulmonary atresia right after a baby is born. In case a baby starts to have symptoms of the disease after coming home, you are required to immediately seek a medical care.
Causes of pulmonary atresia are still unknown but it is important to understand how the disease occurs by knowing the function of the heart.
How the heart works
The heart has four chambers, two on the right and two on the left, which contribute to the pumping of blood for organs throughout the body. Pulmonary arteries are responsible for delivering blood from the right chambers to the lungs. Pulmonary veins deliver the blood that has absorbed oxygen in the lungs back to the left chambers. This oxygen-rich blood is then pumped through the aorta allowing blood to flow throughout the body. Our blood goes in one direction, flows in sync with the heart rhythm as regulated by the opening and closing of heart valves.
Those with pulmonary atresia have the pulmonary valve that is not formed properly, and cannot open to pump blood from the right ventricle to the lungs to absorb oxygen in the organ.
An irregular valve may not be life-threatening for babies in the womb as they receive oxygen through the placenta instead of the lungs.
The heart’s right side is responsible for receiving blood which will flow through the foramen ovale, which is a hole located between the two top chambers. Then the oxygen-rich blood is pumped out of the heart to nourish the whole body.
In pulmonary atresia, the heart has to pump blood to the lungs through another way as the lungs are responsible for providing the body with oxygen after birth. The foramen ovale naturally closes after the baby is born, but pulmonary atresia may cause the hole to stay open after birth.
Among newborn babies, a ductus arteriosus is present as a channel that connects the aorta with the pulmonary artery. It is responsible for partly pushing the oxygen-poor blood to receive oxygen in the lungs. In the organ, the blood absorbs oxygen for the body. The ductus arteriosus naturally closes after the baby is born, but medications may be prescribed to keep the channel open.
Some babies might have both pulmonary atresia and a ventricular septal defect (VSD). VSD is a hole of the wall between the ventricles that allows blood to flow from the right ventricle to the left ventricle. Those with both diseases tend to have multiple problems with the lungs and the arteries that bring blood to the lungs.
Pulmonary atresia with intact ventricular septum (PA/IVS) is a disease present in those that have no VSD. This leads to incomplete development of the right ventricle before birth as the heart chamber cannot receive enough blood.
Although there are no known causes to pulmonary atresia, many factors are found to raise the risk of developing a congenital heart defect, including:
- Having a parent with a congenital heart disease
- Mother being overweight before getting pregnant
- History of smoking, including when being pregnant
- Mother leaving her diabetes untreated or uncontrolled
- Mother taking certain medications while being pregnant, including acne drugs.