Pulmonary valve stenosis usually occurs when the pulmonary valve doesn't grow properly during fetal development. Babies who have the condition often have other congenital heart abnormalities, as well. 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 cusps 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 — then closes to prevent blood from flowing backward into the right ventricle of the heart.

What happens in pulmonary valve stenosis

One or more of the cusps may be defective or too thick, or the cusps 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 — a combination of signs and symptoms, including flushing of the skin and diarrhea — results from the release of a chemical, serotonin, from growths called carcinoid tumors in the digestive system.
  • Rheumatic fever. This complication of an infection caused by streptococcus bacteria, such as strep throat or scarlet fever, may injure the heart valves.
Dec. 02, 2016