Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has a one-way "in" (inlet) valve and a one-way "out" (outlet) valve. Each valve consists of flaps (cusps or leaflets) that open and close like one-way swinging doors.
In the right ventricle, the inlet valve is the tricuspid valve, which opens from the right atrium, and the outlet valve is the pulmonary (pulmonic) valve, which opens into the pulmonary artery.
In the left ventricle, the inlet valve is the mitral valve, which opens from the left atrium, and the outlet valve is the aortic valve, which opens into the aorta.
The mitral and tricuspid valves are held in place by tough, fibrous strings (chordae tendineae) that are connected to thin muscles (papillary muscles) that attach to the walls of the ventricles.
A Look Into the Heart
This cross-sectional view of the heart shows the direction of normal blood flow.
Changes with aging
As people age, the mitral and aortic valves thicken. The aorta becomes stiffer, which increases blood pressure and stress on the aortic valve, and the heart requires additional oxygen to pump blood effectively. These age-related changes may lead to symptoms and complications in older people with heart disease.
Heart valve malfunction
The heart valves can malfunction by
Leaking (termed regurgitation, incompetence, or insufficiency)
Not opening adequately and thus partially blocking the flow of blood through the valve (termed stenosis)
Either problem can greatly interfere with the heart's ability to pump blood. Sometimes a valve has both problems. Faulty valves generally create murmurs and other abnormal heart sounds that a doctor can hear with a stethoscope. Faulty valves can be identified by using echocardiography. Often, minor degrees of regurgitation are not detected with a stethoscope but are detected during echocardiography. Doctors often regard this as a normal finding.
Most faulty valves are not severely abnormal, and they do not affect the person in any way. Symptoms may include leg swelling Swelling Swelling is due to excess fluid in the tissues. The fluid is predominantly water. Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and... read more , shortness of breath Shortness of Breath Shortness of breath—what doctors call dyspnea—is the unpleasant sensation of having difficulty breathing. People experience and describe shortness of breath differently depending on the cause... read more , palpitations Palpitations Palpitations are the awareness of heartbeats. The sensation may feel like pounding, fluttering, racing, or skipping beats. Other symptoms—for example, chest discomfort or shortness of breath—may... read more , fatigue Fatigue Fatigue is when a person feels a strong need to rest and has so little energy that starting and sustaining activity is difficult. Fatigue is normal after physical exertion, prolonged stress... read more , chest pain Chest Pain Chest pain is a very common complaint. Pain may be sharp or dull, although some people with a chest disorder describe their sensation as discomfort, tightness, pressure, gas, burning, or aching... read more , and fainting Fainting Light-headedness (near syncope) is a sense that one is about to faint. Fainting (syncope) is a sudden, brief loss of consciousness during which the person falls to the ground or slumps in a... read more . Doctors often do periodic check-ups because a few faulty valves worsen over time to the point where intervention (repair or replacement) is required to decrease symptoms or prolong survival. Symptoms are not a reliable guide to the existence and severity of valve problems, so echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more (ultrasonography of the heart) is used to detect problems early. Sometimes doctors use exercise testing Stress Testing Stressing the heart (by exercise or by use of stimulant drugs to make the heart beat faster and more forcibly) can help identify coronary artery disease. In coronary artery disease, blood flow... read more to help monitor people with certain heart valve disorders. In general, neither lifestyle measures nor drug treatment can slow the deterioration of an abnormal valve.
Understanding Stenosis and Regurgitation
The heart valves can malfunction either by leaking (causing regurgitation) or by not opening adequately and thus partially blocking the flow of blood through the valve (causing stenosis). Stenosis and regurgitation can affect any of the heart valves. These two disorders are shown below affecting the mitral valve.
Normally, just after the left ventricle finishes contracting and starts to relax and fill with blood again (during diastole), the aortic valve closes, the mitral valve opens, and some blood flows from the left atrium into the left ventricle. Then the left atrium contracts, ejecting more blood into the left ventricle.
As the left ventricle begins to contract (during systole), the mitral valve closes, the aortic valve opens, and blood is ejected into the aorta.
In mitral stenosis, the mitral valve opening is narrowed, and blood flow from the left atrium into the left ventricle during diastole is reduced.
In mitral regurgitation, the mitral valve leaks when the left ventricle contracts (during systole), and some blood flows backward into the left atrium.
Repairing or replacing a heart valve
A faulty valve may be repaired or replaced. Repair may require surgery but now may sometimes be accomplished during heart catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more , particularly when the problem is a valve with stenosis. A stenotic valve can sometimes be stretched open using a procedure called balloon valvuloplasty. In this procedure, a catheter with a balloon at the tip is threaded through a vein or artery into the heart. Once across the faulty valve, the balloon is inflated, separating the valve cusps. This procedure does not require a general anesthetic and allows a quick recovery.
Two types of valves are available for replacement
Bioprosthetic type (made from the heart valve of a pig or cow)
Mechanical valves last for many years, but people with mechanical valves must take the anticoagulant warfarin for the rest of their lives to prevent blood clots from forming in the valve. Taking an anticoagulant increases a person's risk of spontaneous bleeding, such as in their brain (see Overview of Hemorrhagic Stroke Overview of Hemorrhagic Stroke Hemorrhagic strokes include bleeding within the brain (intracerebral hemorrhage) and bleeding between the inner and outer layers of the tissue covering the brain (subarachnoid hemorrhage). ... read more ). Bioprosthetic valves generally deteriorate and require replacement after 10 to 12 years but do not require use of anticoagulants for more than 3 to 6 months after surgery. Some newer bioprosthetic valves are more durable.
Replacing a Heart Valve
A damaged heart valve may be replaced with a mechanical valve made of plastic and metal or with a bioprosthetic valve made of heart valve tissue, usually from pigs, placed in a synthetic ring. There are many types of mechanical valves. A St. Jude valve is commonly used.
Choice of a valve depends on many factors, including characteristics of the valve. A mechanical valve lasts longer than a bioprosthetic valve but requires that anticoagulants be taken indefinitely to prevent the formation of blood clots on the valve. A bioprosthetic valve requires only short-term use of anticoagulants. So whether a person can take anticoagulants is an important factor. For example, anticoagulants may not be appropriate for women of childbearing age because anticoagulants cross the placenta and may affect the fetus. Also considered are
When an aortic valve is being replaced, a mechanical valve is usually chosen for people who are under age 50 and a bioprosthetic valve is chosen for those age 50 or older.
When a mitral valve is being replaced, a mechanical valve is usually chosen for people who are under age 65 and a bioprosthetic valve is chosen for those age 65 or older.
For heart valve replacement, a general anesthetic is given. The heart must be still to be operated on, so a heart-lung machine is used to pump blood through the bloodstream. The damaged valve is removed, and the replacement valve is sewn in place. The incisions are closed, the heart-lung machine is disconnected, and the heart is restarted. The operation takes from 2 to 5 hours. For some people, a heart valve can be replaced using a less invasive procedure (without cutting through the sternum), available at some medical centers. The length of the hospital stay varies from person to person. Full recovery may take 6 to 8 weeks.
Abnormal valves and all replacement valves can become infected. People with replacement valves need to take prophylactic antibiotics, which are antibiotics taken at certain times (for example, before some dental or medical procedures) in order to prevent bacterial infection of the valves (infective endocarditis Infective Endocarditis Infective endocarditis is an infection of the lining of the heart (endocardium) and usually also of the heart valves. Infective endocarditis occurs when bacteria enter the bloodstream and travel... read more ).
Also, blood clots may form on replacement valves. The blood clots may partially block the valve or break loose and travel through the bloodstream to block arteries elsewhere in the body (for example, causing a stroke).
Doctors use computed tomography and echocardiography to monitor replaced valves.
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Heart Association: Heart Valve Disease: Provides comprehensive information on diagnosis and treatment of diseases of the heart valves
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