A disorder of the HEART with obstruction of the outflow of blood from the right ventricle. Narrowing of the pulmonary valve at the exit of the right ventricle and narrowing of the pulmonary artery may cause obstruction. The condition is usually congenital, although it may be caused by RHEUMATIC FEVER. In the congenital condition, pulmonary stenosis may occur with other heart defects and is then known as TETRALOGY OF FALLOT. Breathlessness and enlargement of the heart and eventual heart failure may be the consequence of pulmonary stenosis. Surgery is usually necessary to remove the obstruction.