HEART VALVE DISORDERS
Major problems encountered with heart valves include an improper closing of the valves leading to leakage (regurgitation) or failure to open fully (stenosis). These conditions interfere with the heart’s capacity to pump blood. If the mitral valve leaks, then regurgitation occurs each time the ventricle contracts. As blood is pumped into the aorta some leaks back into the left atrium increasing the volume and the pressure in that compartment. This, in turn, increases the blood pressure in the vessels leading from the lungs to the heart resulting in a pulmonary edema. Rheumatic fever was once the commonest cause of mitral valve regurgitation and heart attacks that damage the structures supporting the valve is its commonest cause. However, in countries where there is poor preventive medicine, rheumatic fever is still common. Repair or replacement of the valve is required if the regurgitation is severe.
The aortic valve may also become leaky, and the most common causes were rheumatic fever and syphilis but this is now rare because of the use of antibiotics. In contrast, aortic valve stenosis is mainly a disease of the elderly (over 60 years) and is the result of the valve becoming calcified. The left ventricle wall thickens as the heart strains to pump sufficient blood through the narrow opening and the enlarged heart muscle requires extra oxygen and nutrients from the coronary arteries. Eventually the output of blood from the heart becomes insufficient for the body's needs and the resulting heart failure causes shortness of breath and fatigue. The treatment is to replace the aortic valve, preferably before the left ventricle becomes irreparably damaged.
Problems can also occur with the tricuspid valve. However, regurgitation usually requires little treatment. Stenosis of the tricuspid valve is rare, again, because the damage was mainly associated with rheumatic fever.