Patient Education: Heart Valve

The Function of Heart Valves

Your heart is your body's pump.  In your lifetime your heart will beat more than two billion times, pumping about 180 million liters of blood!  If you put your two fists together, you will have the approximate size of a human heart.  Your heart is divided into four chambers; two atria and two ventricles.  There is one atrium and one ventricle on both the right side and the left side of the heart.

When blood flows through your heart, it first flows through an atrium and then into a ventricle.  Within each of the four chambers there is a valve which allows blood to pass into the next chamber, or an artery.

The left side of the heart must develop a pressure that is approximately ten times higher than than the pressure created on the right side of the heart because it is supplying your entire body with oxygenated blood.  Oxygenated blood is returned to the left atrium of the heart in the pulmonary veins.  Blood then flows from your left atrium through the mitral valve into your left ventricle.  It is then transported to your body through the aorta, the largest artery in your body.  Because of the pressure it must maintain to perform its function, the heart valves on the left side of your heart are most often affected by disease.

After touring the body, the blood has very little oxygen left.  To get a new supply of oxygen, the deoxygenated blood needs to go to the lungs.  In order to get to the lungs, the blood needs to return to the heart, entering through the right atrium.  The blood is pumped from the right atrium through the tricuspid valve, pushing the tricuspid valve's leaflets aside.  As the ventricle starts to contract, drawing in the blood, the tricuspid valve's leaflets snap shut and the cusps of the pulmonary valve open allowing blood to flow out of the ventricle through the pulmonary artery and on to the lungs.  As the ventricle relaxes, the pulmonary valve then closes. After leaving the right ventricle, the blood heads towards the lungs to give up carbon dioxide and water vapor in exchange for the oxygen the body needs.  It then returns to the heart via the pulmonary veins and enters the left atrium.  Once the blood moves to the left ventricle, it is ready to start its circuit all over again.

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What is Mitral Valve Prolapse?

If a mitral valve is not as tight as it should be, it may allow one of the portions of the valve to bend backwards towards the upper chamber (left atrium) during the heart's contraction. This is called prolapse. This movement can create a clicking sound that can be heard with a stethoscope.

Mitral valve prolapse is not uncommon and affects between five to twenty percent of the general population, most of them women. The symptoms of mitral valve prolapse usually begin after the early teenage years (approximately age 14 in girls and in 15 in boys) yet people of any age may be affected.

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What is Mitral Regurgitation?

Mitral Regurgitation occurs when there is a small leakage of blood backwards into the upper chamber of the heart (left atrium) from the lower chamber of the heart (left ventricle). While this can be heard as a heart murmur the heart is still able to function normally. The heart still pumps and receives an adequate blood supply. Most cases of mitral valve prolapse do not tend to worsen over time.

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What is the cause of Mitral Stenosis?

Mitral stenosis appears mostly in people who have had rheumatic fever, which can cause damage to heart valves, or those with a family history of rheumatic fever and stroke. Symptoms can be triggered by an episode of atrial fibrillation (rapid, incomplete contractions of the atria), pregnancy, respiratory infection, endocarditis, or other cardiac disorders or body stresses.

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What is Aortic Stenosis?

Aortic stenosis is a condition in which one of the valves in the heart (the aortic valve) has become stenotic (narrowed/constricted) and does not open normally. When this occurs, the ability of the heart (left ventricle) to pump blood out of the heart to the aorta and other arteries is affected. The body's organs will not receive a sufficient supply of oxygen-rich blood, and the blood may "back up" into the lungs, causing shortness of breath.

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What is Aortic Regurgitation?

When the aortic valve does not close properly, the blood that is being pumped can leak backward towards the valve. As a result, the left ventricle needs to pump more blood than it normally can and becomes gradually larger as a result of the extra work it needs to perform.