CausesBy Mayo Clinic staff
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Pulmonary valve stenosis usually occurs when the pulmonary valve doesn't grow properly during fetal development. Other heart abnormalities also are often present at birth (congenital) in babies who have pulmonary valve stenosis. It's not known what causes the valve to develop abnormally.
Normal pulmonary valve anatomy
The pulmonary valve is made up of three thin pieces of tissue called leaflets that are arranged in a circle. With each heartbeat, the valve opens in the direction of blood flow — into the pulmonary artery and continuing to the lungs — and then closes to prevent blood from flowing backward into the right ventricle of the heart.
What happens in pulmonary valve stenosis
In pulmonary valve stenosis, one or more of the leaflets may be defective or too thick, or the leaflets may not separate from each other properly. If this happens, the valve doesn't open correctly, restricting blood flow.
Other contributing conditions
Sometimes other medical conditions or having an artificial valve can cause the condition in older people.
- Carcinoid syndrome. This syndrome is a combination of signs and symptoms, including flushing of the skin and diarrhea. Carcinoid syndrome results from the release of a chemical, serotonin, from growths called carcinoid tumors located in the digestive system. People with carcinoid syndrome may develop problems with their heart valves from the serotonin.
- Rheumatic fever. This is a complication of an infection caused by streptococcus bacteria, such as strep throat or scarlet fever. Rheumatic fever may injure the heart valves.
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