Valvular heart disease

Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and bicuspid valves on the left side of heart and the pulmonary and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.

Stenosis of the aortic valve is characterized by a thickening of the valvular annulus or leaflets that limits the ability of blood to be ejected from the left ventricle into the aorta. It is typically the result of aging, occurring in 12.4% of the population over 75 years of age and represents the most common cause of outflow obstruction in the left ventricle. Stenosis is typically the result of valvular calcification, but may be the result of a congenitally malformed bicuspid aortic valve. This defect is characterized by the presence of only two valve leaflets and affects up to 1% of the population, making it one of the most common cardiac abnormalities. It may occur in isolation or in concert with other cardiac anomalies.

Pulmonary valve insufficiency occurs commonly in healthy individuals to a very mild extent and does not require intervention. More appreciable insufficiency it is typically the result of damage to the valve due to cardiac catheterization, intra-aortic balloon pump insertion, or other surgical manipulations. Additionally, insufficiency may be the result of carcinoid syndrome, inflammatory processes such a rheumatoid disease or endocarditis, or congenital malformations. It may also be secondary to severe pulmonary hypertension.

Inflammation of the heart valves due to any cause is called valvular endocarditis; this is usually due to bacterial infection but may also be due to cancer (marantic endocarditis), certain autoimmune conditions (Libman-Sacks endocarditis, seen in systemic lupus erythematosus) and hypereosinophilic syndrome (Loeffler endocarditis). Certain medications have been associated with valvular heart disease, most prominently ergotamine derivatives pergolide and cabergoline.

The evaluation of individuals with valvular heart disease who are or wish to become pregnant is a difficult issue. Issues that have to be addressed include the risks during pregnancy to the mother and the developing fetus by the presence of maternal valvular heart disease as an intercurrent disease in pregnancy. Normal physiological changes during pregnancy require, on average, a 50% increase in circulating blood volume that is accompanied by an increase in cardiac output that usually peaks between the midportion of the second and third trimesters. The increased cardiac output is due to an increase in the stroke volume, and a small increase in heart rate, averaging 10 to 20 beats per minute. Additionally uterine circulation and endogenous hormones cause systemic vascular resistance to decrease and a disproportionately lowering of diastolic blood pressure causes a wide pulse pressure. Inferior vena caval obstruction from a gravid uterus in the supine position can result in an abrupt decrease in cardiac preload, which leads to hypotension with weakness and lightheadedness. During labor and delivery cardiac output increases more in part due to the associated anxiety and pain, as well as due to uterine contractions which will cause an increases in systolic and diastolic blood pressure.