About Valvular Heart Disease
Heart valve disease occurs when one or more valves do not open and/or close properly, robbing the heart of its normal efficiency.
There are two types of valve disease — stenosis and regurgitation.
When valves don't open completely, the condition is known as stenosis.
When a valve is stenotic, blood has to flow through a smaller opening than normal forcing the chamber behind the valve to pump blood more forcefully than usual. Stenosis results from progressive hardening or stiffening of valve leaflets from calcium deposits or scarring. This causes abnormal stress and strain on the heart muscle, which can become irreversibly weakened.
In aortic stenosis, the aortic valve does not open normally. Compare the relatively closed aortic valve in aortic stenosis to the valve opening in a normal heart. Because the left ventricle must pump extra hard to eject blood across the stenotic valve, the left ventricular free wall and inter-ventricular septum are markedly thickened. However, there is no enlargement of the heart chambers or arteries.
The left atrium, pulmonary veins, pulmonary artery and right ventricle remain normal in size (as illustrated) throughout most of the natural course of the disease.
In mitral stenosis, the mitral valve fails to open normally. Compare the relatively closed mitral valve in mitral stenosis to the valve opening in the normal heart. This chamber is normal to small in volume, because of the impediment to flow into the left ventricle. However, because blood backs up behind the valve, the left atrium, pulmonary artery and right ventricle are enlarged. The left ventricular free wall and inter-ventricular septum remain normal in thickness.
The pulmonary veins, pulmonary artery and right ventricle will become overfilled, enlarge and develop higher than normal pressures, leading to stiff lungs and difficulty in breathing.
When valves don't close completely, the condition is known as regurgitation or insufficiency.
The valves, themselves, or supporting structures below, may be loose, torn or distorted, allowing a gap to develop between the valve leaflets. If the valve doesn't close completely, blood leaks backward into the cardiac chamber at the same time it is receiving blood from the preceding chamber. The result is over-stretching of the heart muscle, which, if sufficiently severe and prolonged, can permanently damage the heart muscle.
In aortic regurgitation, the aortic valve fails to close normally and, therefore, leaks. Compare the difference in the size of the opening of the valve in aortic regurgitation with that in a normal heart. Because of the leak, the left ventricle is markedly enlarged, as the aorta. The left ventricular free wall and inter-ventricular septum are of normal thickness. The pulmonary artery and right ventricle are of normal volume.
In mitral regurgitation, the mitral valve does not close properly, and, therefore, leaks. Compare the differences in the circumference of the mitral valve and the size of its opening in mitral regurgitation with that in a normal heart. As a result of the leak backward from the left ventricle, the left atrium, pulmonary artery and right ventricle are enlarged. The left ventricle also is enlarged (it receives the leaked volume as well as the normal forward flow), but the left ventricular free wall and inter-ventricular septum remain normal in thickness.