Blood is pumped through your heart in only one direction. Heart valves play key roles in this one-way blood flow, opening and closing with each heartbeat. Pressure changes behind and in front of the valves allow them to open their flap-like "doors" (called cusps or leaflets) at just the right time, and then close them tightly to prevent a back flow of blood.
There are 4 valves in the heart:
- Tricuspid valve, which lies between the right atrium and right ventricle
- Pulmonary (pulmonic) valve, between the right ventricle and the pulmonary artery
- Mitral valve between the left atrium and left ventricle
- Aortic valve between the left ventricle and the aorta
Two types of problems can disrupt blood flow though the valves: regurgitation or stenosis.
Regurgitation is also called insufficiency or incompetence. Regurgitation happens when a valve doesn't close properly and blood leaks backward instead of moving in the proper one-way flow. If too much blood flows backward, only a small amount can travel forward to your body's organs. Your heart tries to make up for this by working harder, but with time your heart will become enlarged (dilated) and less able to pump blood through your body.
Stenosis happens when the leaflets do not open wide enough and only a small amount of blood can flow through the valve. Stenosis happens when the leaflets thicken, stiffen, or fuse together. Because of the narrowed valve, your heart must work harder to move blood through your body.
In both circumstances the heart must work harder to pump the blood. In valvular stenosis, when the valve narrows, the heart’s pumping ability decreases, leading to several problems. For example, if the mitral valve is narrow when the left atrium contracts, less blood is able to fill the ventricle. This limits the amount of blood that is then pumped out to the body.
When a valve fails to close completely, blood can flow back into the chamber that it was coming from. This valve condition also impairs the heart’s ability to pump the necessary volume of blood to the rest of the body. So for example if the mitral valve does not close completely when the left ventricle contracts, blood passes back into the left atrium as well as forward through the aorta. The blood “regurgitating’ or being forced back into the atrium can cause pressure to build in the atrium and even back into the lungs. The excess pressure in the lungs limits their efficiency.
What causes valve disease?
There are three main causes of valvular heart disease. These are birth defects known as congenital heart disease, rheumatic fever and age.
Congenital heart disease
Some people are born with an abnormal heart valve and for many of these people they never cause a problem. However in some cases, as people get older these valves are no longer able to function as well as before. Stenosis and/or regurgitation can then occur.
Abnormal valves are also more likely to become infected than healthy valves. This can cause a condition known as endocarditis and this can lead to problems with valve function.
This is the most common cause of valve disease. Rheumatic fever itself is not very common today, however 20-30 years ago it affected many people.
People, who contracted rheumatic fever as a child, can experience problems with the valves in their heart as adults.
Rheumatic fever can affect more than one valve and can cause both stenosis and regurgitation.
In older people the most common cause of valve disease is thickening of the valve. This means that the valve cannot open and close as easily as before. This restricts the blood flow.