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 risks of heart disease in pregnancy?
Important risk of heart disease in pregnancy is that the mother may go into heart failure with severe breathlessness. A potential risk of miscarriage is also there. In a rare form of heart disease with obstruction in the great vessel (aorta), a portion of the enlarged vessel may rupture during the strain of delivery, with catastrophic results. Another rare form of heart disease specific for pregnancy is peripartum cardiomyopathy which produces weakness of the heart muscle during pregnancy, usually improving after delivery. Severe forms of peripartum cardiomyopathy is also a high risk condition, leading to heart failure near the time of delivery or soon after.
Which types of heart diseases are poorly tolerated in pregnancy?
In general, any severe heart disease can worsen significantly during pregnancy as the work load of the heart increases markedly in later pregnancy. Heart diseases with some obstruction in the flow of blood is more likely to be worsened in pregnancy than leaks in the valves. Important obstructions which worsen in pregnancy are mitral stenosis (narrowing of the valve between the left atrium and left ventricle), aortic stenosis (narrowing of the valve between the left ventricle and aorta) and coarctation of aorta (narrowing of a region of the aorta). Birth defects of the heart which increase the blood pressure in the lungs markedly (Eisenmenger syndrome) also carries high risk in pregnancy. In Eisenmenger syndrome pregnancy is better avoided. In the other three obstructive conditions mentioned above, pregnancy can be considered after relieving the obstruction by treatment (surgery or dilatation using a balloon catheter).
At what term of pregnancy does women with heart disease start worsening?
Blood volume in the body progressively increases as the pregnancy advances. By about five months of pregnancy there is a significant increase in blood volume so that women with most severe forms of heart disease become more symptomatic. This will continue as the pregnancy advances unless the disease is relieved by treatment.