What causes narrowing of heart valves?
Narrowing of heart valves can occur at birth. Then it is called congenital narrowing of heart valves. Narrowing of heart valves is given the technical name ‘stenosis‘. Narrowing of aortic valve (valve between the left ventricle – lower muscular chamber of the heart – and the aorta – large blood vessel carrying oxygenated blood to the body) is known as aortic stenosis. Narrowing the valve between the left upper and lower chambers of the heart is known as mitral stenosis. Corresponding names on the right side of the heart are tricuspid stenosis and pulmonary stenosis.
An important cause of narrowing of heart valves in developing countries is rheumatic fever. Degeneration of valve structures by age can lead to narrowing of the aortic valve causing aortic stenosis. As time goes by, these valves can get calcified, with deposit of compounds containing calcium. Then it is called calcific aortic stenosis. Birth defect of the aortic valve in which it has only two cusps instead of the normal three is known as bicuspid aortic valve. Bicuspid aortic valve can degenerate earlier than normal aortic valve causing aortic stenosis. Valves can also get narrowed due to deposition of other materials in certain diseases (infiltrative disorders).
What is valvular heart disease?
Valvular heart disease is a heterogenous group of disorders of the heart in which various heart valves are diseased. The valves could be abnormal by birth (congenital valvular abnormalities) or the abnormality could be acquired in the course of life (acquired valvular heart disease). Important congenital valvular heart diseases are bicuspid aortic valve (aortic valve having two cusps instead of the normal three), congenital aortic stenosis (narrowing of the orifice of the aortic valve) and congenital pulmonary stenosis (narrowing of the orifice of pulmonary valve). Rarely the mitral valve could also be narrowed by birth (congenital mitral stenosis).
What are the important acquired causes of valvular heart disease?
In the developing world, the most common cause of valvular heart disease is rheumatic fever and its sequelae (rheumatic heart disease). In the developed world, more common would be degenerative valvular heart disease. Reduced blood supply to the heart muscle (ischemic heart disease) can also damage the function of the heart valve. Other causes are infections (infective endocarditis), carcinoid heart disease, heart disease induced by medications used for obesity and traumatic damage to the heart valves.
How do valvular heart disease manifest?
Manifestation of the valvular heart disease depends on the valve involved, severity of involvement and the rapidity of progression. Valvular damage could produce leakage of the valve (regurgitation) or narrowing of the orifice (stenosis). Leakage of the heart valve produces volume overloading of the chambers involved. For example, leakage of the mitral valve (mitral regurgitation) between left atrium and left ventricle causes enlargement of both these chambers. Narrowing of mitral valve (mitral stenosis) produces enlargement of the left atrium which is before the valve, but not the left ventricle, which is after the valve in the blood flow sequence.