Heart valves are thin membranes located within the chambers of the heart. They have leaflets or cusps which allow blood to flow in only one direction through the heart.
There are four main valves in the heart:
a) The two atrioventricular valves (AV valves) are called mitral and tricuspid valves. They are located between the upper (atria) and lower (ventricles) chambers of the heart. They prevent backflow of blood from the ventricles to the atria during their contraction. The mitral valve (bicuspid valve) has two cusps or leaflets. Usually, the tricuspid valve has three cusps. Sometimes there may be two or four cusps. Upturn or prolapse of the AV valves during ventricular contraction is prevented by small muscles within the heart (papillary muscles) that attach to these cusps via the cord-like tendons (chordae tendineae).
b) The two semilunar valves are called aortic and pulmonary valves. They are located in the arteries leaving the heart. They open during ventricular contraction allowing blood to exit but prevent backflow of blood from the arteries.
Conditions affecting the heart valves:
Regurgitation – full closure of valve prevented causing backflow of blood as seen in mitral, tricuspid, aortic or pulmonary regurgitation. It could be due to certain conditions like valve prolapse, congenital heart defects, ischemic heart disease, cardiomyopathy, etc.
Stenosis – narrowing of valve due to thickening. It could be mitral, tricuspid, aortic or pulmonary valve stenosis. Rheumatic fever, endocarditis, coronary artery disease, hypertension, heart attack, etc. can cause valve stenosis.
Diseases of the heart valve are diagnosed by echocardiography, MRI, cardiac catheterization, radionuclide scan, etc. Treatment is aimed at lessening symptoms and protecting the valve from further damage with medications. Defective valves are repaired or replaced with surgery.