This results in a narrower opening for the blood to be pumped through, making it harder for the pumping heart chamber to push the valve open and the blood out. Blood must then flow through a smaller opening so less blood gets pushed through the valve into the next chamber or artery. The valve leaflets may be damaged or supportive structures that help the valve function may become loose or torn causing an insufficient or incomplete closure of the valve. The result is a backward flow of blood. As the valve closes, it does not close tightly enough, and blood that was pumped into the next chamber or artery leaks back in the wrong direction.
People typically tolerate stenotic valves better than incompetent ones.
Sometimes there can be disease of the annulus that affects valve function. Severe calcification of the annulus may affect its ability to change shape and open completely during the cardiac cycle. The annulus may also become enlarged due to congenital or acquired disease, which would prevent the leaflets from meeting properly when closed and thus cause regurgitation. The leaflets may also calcify and thicken, which would impair their mobility. CAD may affect the ability of the papillary muscles and chordae tendineae to work properly due to impaired or damaged heart muscle surrounding these structures.