There are four major valves in a person's heart that direct blood flow forward through the chambers of the heart. Valvular heart disease can occur with any one or a combination of the valves, and it will often lead to heart failure if left untreated.
Diseases of the mitral or aortic valves (the valves of the left side of the heart) are most common affecting more than 5 percent of the population.
Heart valves can have one of two malfunctions:
Regurgitation: The valve(s) does not close completely, causing the blood to flow backward instead of forward through the valve
Stenosis: The valve(s) opening becomes narrowed or does not form properly, inhibiting the flow of blood out of the ventricle or atria. The heart is forced to pump blood with increased force in order to move blood through the stiff (stenotic) valve(s).
Heart valves can have both malfunctions at the same time (regurgitation and stenosis). When heart valves fail to open and close properly, the implications for the heart can be serious, possibly hampering the heart's ability to pump blood adequately through the body. Heart valve problems are one cause of heart failure.