What is pulmonary artery stenosis?
Pulmonary artery stenosis is a narrowing (stenosis) that occurs in the pulmonary artery, a large artery that sends oxygen-poor blood into the lungs to be enriched with oxygen. The narrowing may occur in the main pulmonary artery and/or in the left or right pulmonary artery branches. This narrowing makes it difficult for blood to reach the lungs to pick up oxygen. Without enough oxygen, the heart and body cannot function as they should. In an effort to overcome the narrowing, the pressure in the right ventricle (the chamber that pumps blood into the pulmonary arteries) rises to levels that can be damaging to the heart muscle.
What causes pulmonary artery stenosis?
Pulmonary artery stenosis is a congenital heart defect, meaning it is a defect that is inborn or exists at birth. Stated another way, the defect is an abnormality, not a disease. Pulmonary artery stenosis is often present in combination with other congenital heart defects, such as:
- Tetralogy of Fallot – a four-pronged defect consisting of: 1) a ventricular septal defect, 2) a narrowing at or just beneath the pulmonary valve, 3) a right ventricle that is more muscular than normal, 4) an aorta that lies directly over the ventricular septal defect
- Pulmonary atresia – absence of a pulmonary valve, preventing blood from flowing from the right ventricle into the pulmonary artery and onward to the lungs
- Truncus arteriosus – the formation of only one combined artery instead of the normal two outlets from the heart, the aorta and pulmonary artery
- Pulmonary valve stenosis – problems with the pulmonary valve (for example, development of less than three leaflets, leaflets that may be partially fused together, thick leaflets that do not open all the way) that make it more difficult for the valve leaflets to open and permit blood to flow from the right ventricle to the lungs
- Patent ductus arteriosus – an open passageway between the pulmonary artery and the aorta. Normally, this passageway closes on its own within a few hours of birth, but when it does not, surgery or an outpatient catheter-based procedure is needed to close the opening
Other causes of pulmonary artery stenosis can include: other syndromes that affect the heart (such as rubella syndrome [a group of heart and other health problems in an infant caused by rubella infection in the mother during pregnancy] and Williams syndrome [a group of abnormalities affecting the heart and other organs]) and surgical procedures used to correct other heart defects (for example, pulmonary artery banding - a purposeful narrowing of the artery to reduce blood flow to the lungs).