HEART VALVES WORK

How the heart valves work
At the start of each heartbeat, blood returning from the body and the lungs fills the heart's two upper chambers. The mitral and tricuspid valves are located at the bottom of these chambers. As the blood builds up in the upper chambers, these valves open to allow blood to flow into the lower chambers of your heart. After a brief delay, as the lower chambers begin to contract, the mitral and tricuspid valves shut tightly. This stops blood from flowing backward.
As the lower chambers contract, they pump blood through the pulmonary and aortic valves. The pulmonary valve opens to allow blood to flow from the right lower chamber into the pulmonary artery. This artery carries blood to the lungs to get oxygen. At the same time, the aortic valve opens to allow blood to flow from the left lower chamber into the aorta. This aorta carries oxygen-rich blood to the body. As the contraction ends, the pulmonary and aortic valves shut tightly. This stops blood from flowing backward into the lower chambers.
Heart valve problems
Heart valves can have three basic kinds of problems:
Regurgitation, or backflow, occurs when a valve doesn't close tightly. Blood leaks back into the chamber rather than flowing forward through the heart or into an artery. In the United States, backflow is most often due to prolapse. "Prolapse" is when the flaps of the valve flop or bulge back into an upper heart chamber during a heartbeat. Prolapse mainly affects the mitral valve, but it can affect the other valves as well.
Stenosis occurs when the flaps of a valve thicken, stiffen, or fuse together. This prevents the heart valve from fully opening, and not enough blood flows through the valve. Some valves can have both stenosis and backflow problems.
Atresia occurs when a heart valve lacks an opening for blood to pass through.
You can be born with heart valve disease or you can acquire it later in life. Heart valve disease that develops before birth is called a congenital valve disease. Congenital heart valve disease can occur alone or with other congenital heart defects. Congenital heart valve disease usually involves pulmonary or aortic valves that don't form properly. These valves may not have enough tissue flaps, they may be the wrong size or shape, or they may lack an opening through which blood can flow properly. Acquired heart valve disease usually involves the aortic or mitral valves. Although the valve is normal at first, disease can cause problems to develop over time. Both congenital and acquired heart valve disease can cause stenosis or backflow.
Outlook
Many people have heart valve defects or disease but don't have symptoms. For some people, the condition will stay largely the same over their lifetime and not cause any problems. For other people, the condition will worsen slowly over time until symptoms develop. If not treated, advanced heart valve disease can cause heart failure, stroke, blood clots, or sudden death due to sudden cardiac arrest. Currently, no medicines can cure heart valve disease. However, lifestyle changes and medicines can relieve many of the symptoms and problems linked to heart valve disease. They also can lower your risk of developing a life-threatening condition, such as stroke or sudden cardiac arrest. Eventually, you may need to have your faulty heart valve repaired or replaced. Some types of congenital heart valve disease are so severe that the valve is repaired or replaced during infancy or childhood or even before birth. Other types may not cause problems until you're middle-aged or older, if at all.
What causes heart valve disease?
Heart conditions and other disorders, age-related changes, rheumatic fever, and infections can cause acquired heart valve disease. These factors change the shape or flexibility of once-normal valves. The cause of congenital heart valve defects isn't known. These defects occur before birth as the heart is forming. Congenital heart valve defects can occur alone or with other types of congenital heart defects.
Heart conditions and other disorders
Heart valves can be stretched and distorted by:
Damage and scar tissue due to a heart attack or injury to the heart.
Advanced high blood pressure and heart failure. These conditions can enlarge the heart or the main arteries.
Narrowing of the aorta due to the buildup of a fatty material called plaque inside the artery. The aorta is the main artery that carries oxygen-rich blood to the body. The buildup of plaque inside an artery is called atherosclerosis.
Age-related changes
Men older than 65 and women older than 75 are prone to developing calcium and other deposits on their heart valves. These deposits stiffen and thicken the valve flaps and limit blood flow (stenosis). The aortic valve is especially prone to this problem. The deposits resemble those seen in the narrowed and hardened blood vessels of people who have atherosclerosis. Some of the same processes may cause both atherosclerosis and heart valve disease.
Rheumatic fever
Some people have heart valve disease due to untreated strep throat or other infections with strep bacteria, which progress to rheumatic fever. When the body tries to fight the strep infection, one or more heart valves may be damaged or scarred in the process. The aortic and mitral valves are most often affected. Symptoms due to heart valve damage often don't appear until many years after recovery from rheumatic fever. Today, most people with strep infections are treated with antibiotics before rheumatic fever develops. It's very important to take the entire amount of antibiotics your doctor prescribes for strep throat, even if you feel better. Heart valve disease due to rheumatic fever mainly affects older people who had strep infections before antibiotics were available. It also affects people from developing countries, where rheumatic fever is more common.
Infections
Common germs that enter through the bloodstream and get carried to the heart can sometimes infect the inner surface of the heart, including the heart valves. This rare, but sometimes life-threatening infection is called endocarditis. The germs can enter the bloodstream through needles, syringes, or other medical devices and through breaks in the skin or gums. Usually the body's defenses fight off the germs and no infection occurs. Sometimes these defenses fail, which leads to endocarditis. Endocarditis can develop in people who already have abnormal blood flow through a heart valve due to congenital or acquired heart valve disease. The abnormal blood flow causes blood clots to form on the surface of the valve. The blood clots make it easier for germs to attach to and infect the valve. Endocarditis can worsen existing heart valve disease.
Other conditions and factors linked to heart valve disease
A number of other conditions and factors are sometimes linked to heart valve disease. However, it's often unknown how these conditions actually cause heart valve disease.
1.Systemic lupus erythmatosis (SLE). SLE and other immune diseases can affect the aortic and mitral valves.
2.Carcinoid syndrome. Tumors in the digestive tract that spread to the liver or lymph nodes can affect the tricuspid and pulmonary valves.
3.Metabolic disorders. Relatively uncommon diseases, such as Fabry disease and hyperlipidemia, can affect the heart valves.
4.Diet medicines. The use of fenfluramine and phentermine ("fen-phen") has sometimes been linked to heart valve problems. These problems typically stabilize or improve after the medicine is stopped.
5.Radiation therapy. Radiation therapy to the chest area can cause heart valve disease. This therapy is used to treat cancer. Heart valve disease due to radiation therapy may not cause symptoms for as many as 20 years after the therapy ends.