Acquired Valvular Disorders
The valves of the heart control the flow of blood through the heart into the pulmonary artery and aorta by opening and closing in response to the blood pressure changes as the heart contracts and relaxes through the cardiac cycle. The atrioventricular valves separate the atria from the ventricles and include the tricuspid valve, which separates the right atrium from the right ventricle, and the mitral valve, which separates the left atrium from the left ventricle. The tricuspid valve has three leaflets; the mitral valve has two. Both valves have chordae tendineae that anchor the valve leaflets to the papillary muscles and ventricular wall. The semilunar valves are located between the ventricles and their corresponding arteries. The pulmonic valve lies between the right ventricle and the pulmonary artery; the aortic valve lies between the left ventricle and the aorta. Figure 29-1 shows valves in the closed position.When any of the heart valves do not close or open properly, blood flow is affected. When valves do not close completely, blood flows backward through the valve in a process called regurgitation. When valves do not open completely, a condition called stenosis, the flow of blood through the valve is reduced.Disorders of the mitral valve fall into the following categories: mitral valve prolapse (ie, stretching of the valve leaflet into theatrium during systole), mitral regurgitation, and mitral stenosis.Disorders of the aortic valve are categorized as aortic regurgitation and aortic stenosis. These valvular disorders lead to various symptoms that, depending on their severity, may require surgical repair or replacement of the valve to correct the problem (Fig. 29-2). Tricuspid and pulmonic valve disorders also occur, usually with fewer symptoms and complications. Regurgitation and stenosis may occur at the same time in the same or different valves.