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 are the important types of heart diseases in children?
Most of the important heart diseases in children are birth defects of the heart (congenital heart disease). But there are other types of heart diseases which can also be seen in children. These are rheumatic heart disease as a sequela of rheumatic fever, electrical disorders of the heart, inflammatory diseases of the heart, Kawasaki disease and heart muscle disorders known as cardiomyopathies. Though coronary artery disease is by and large a disease of the adult population, some rare inherited disorders like homozygous hypercholesterolemia can cause a heart attack in older children.
Kawasaki disease is disease of children associated with fever, swelling of lymph glands, redness of eyes and in some cases involvement of blood vessels of the heart (coronary arteries). As the disease progresses, the coronary arteries may be become enlarged in an irregular fashion (aneurysms) which can lead to formation of clots in these blood vessels. Clots within coronary arteries can block the blood supply to a region of the heart and produce a heart attack. Kawasaki disease is one of the causes of heart attack in children, though rare.
Rheumatic heart disease in children mostly manifest as leaks of major heart valves – mitral valve and aortic valve. In severe cases, this can lead to heart failure. Electrical disorders of the heart can lead to rapid or irregular heart rhythm. Sometimes they can have low heart rate due to congenital complete heart block, an electrical disorder in which the pacemaker signals from the natural pacemaker of the heart in its upper chamber does not get conducted to the lower chamber. Inflammatory disease of the heart could involve any of the three layers of the heart and in severe cases lead to heart failure. Congenital heart diseases can involve any chamber, the wall between the chambers, the heart valves or the great vessels arising from the heart. They vary from simple small holes in the wall between the chambers to very complex life threatening defects. Homozygous hypercholesterolemia is an inherited disorder with very high blood cholesterol levels and can lead to formation of blocks in the blood vessels of the heart very early in life.