What is the pulmonary valve?
The pulmonary valve, one of two semilunar valves in the heart, is the valve that is situated between the right ventricle and the pulmonary artery, the artery that transports deoxygenated blood to the lungs from the heart. It is called the pulmonary valve because it leads to the pulmonary artery. The pulmonic valve, like the tricuspid valve and aortic valve, has three leaflets (only the bicuspid/mitral valve has two leaflets) that open and close to regulate blood flow and prevent blood from leaking back (regurgitating) into the right ventricle.
What does the pulmonary valve look like?
The average size of a pulmonary valve in adults is 2.5 cm². The three leaflets of the valve—the left cusp, the right cusp and the anterior cusp—attach to the ventricular septum (the wall that separates the heart’s lower chambers) and the pulmonary annulus, a fibrous ring similar to that of the aortic valve. Unlike the tricuspid and mitral valves, the pulmonary valve is not supported by heart strings (chordae tendineae). The leaflets resemble half-moons and each cusp has a free edge and small fibrous nodule at the centre of it. Like the aortic valve, there is also a supportive rim (lunula) that ensures tight closure of the valve.
What is the function of the pulmonary valve? How does it function?
The pulmonary valve functions to regulate blood that flows between the right ventricle (the heart’s bottom right chamber) and the pulmonary artery and to prevent regurgitation as blood is pumped from the right ventricle to the pulmonary artery. Normally, pressure increases in the right ventricle during ventricular systole (contraction). Once it exceeds pulmonary pressure, the pulmonary valve opens, allowing blood to pass through from the right ventricle to the pulmonary artery. Then, as soon as ventricular systole ends, pressure drops swiftly and pulmonary pressure forces the pulmonary valve shut.
What happens when the pulmonary valve doesn’t function properly?
If the pulmonary valve is defective or damaged, dysfunction can occur and cause symptoms and complications. Pulmonary valve disease is rare. When there are problems, it is usually due to a congenital (present from birth) abnormality, such as pulmonary atresia, tetralogy of fallot, great transposition of the arteries or double outlet right ventricle. Pulmonary valve stenosis and pulmonary valve regurgitation are two potentially serious problems that are associated with congenital conditions. They can develop through life, however, due to rheumatic heart disease, carcinoid syndrome, infective endocarditis, etc.