CHAPTER 60
Heart Valve Disorders
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—see art on page 317). Each ventricle has a one-way “in” (inlet) valve and a one-way “out” (outlet) valve. 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. Each valve consists of flaps (cusps or leaflets) that open and close like one-way swinging doors.
The heart valves can malfunction either by leaking (termed regurgitation) or by 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 an echocardiogram. Doctors often regard this as a normal finding.
A faulty valve may be repaired or replaced. Repair may require surgery but may sometimes be accomplished during heart catheterization, 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 balloon-tipped catheter is threaded through a vein and eventually into the heart. Once inside 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, a mechanical type and one made from the heart valve of a pig (bioprosthetic). Mechanical valves last for many years, but people with mechanical valves must take anticoagulants for the rest of their lives to prevent blood clots from forming in the valve. Bio-prosthetic valves generally deteriorate and require replacement after 10 to 12 years but do not require use of anticoagulants for more than a few months after surgery. Abnormal valves and all replacement valves can become infected, and people 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).
Changes With Aging: As people age, the mitral and aortic valves thicken. The aorta becomes stiffer, which increases blood pressure and stress on the mitral 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.
Mitral Regurgitation
Mitral regurgitation (mitral valve regurgitation, mitral incompetence, mitral insufficiency) is leakage of blood backward through the mitral valve each time the left ventricle contracts.
Heart attack is the most common cause of mitral regurgitation except in places where antibiotics are not readily available to treat strep infections.
When regurgitation is severe, people may have shortness of breath.
Mild regurgitation may not need treatment, but people with more severe regurgitation may need to take angiotensin-converting enzyme inhibitors or have surgery to replace the damaged heart valve.
As the left ventricle pumps blood into the aorta, some blood leaks backward into the left atrium, increasing blood volume and pressure there. The increased blood pressure in the left atrium increases blood pressure in the veins leading from the lungs to the heart (pulmonary veins) and causes the left atrium to enlarge to accommodate the extra blood leaking back from the ventricle. An extremely enlarged atrium often beats rapidly in an irregular pattern (a disorder called atrial fibrillation), which reduces the heart’s pumping efficiency because the fibrillating atrium is quivering rather than pumping. Consequently, blood does not flow through the atrium normally, and blood clots may form inside the chamber. If a clot breaks loose (becoming an embolus), it is pumped out of the heart and may block an artery, possibly causing a stroke or other damage.
Severe regurgitation can result in heart failure, in which increased pressure in the atrium causes fluid accumulation (congestion) in the lungs, or in which reduced forward flow of blood from the ventricle to the body deprives organs of the proper amount of blood. The left ventricle may gradually dilate and weaken, further worsening heart failure.
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.
Cause
Rheumatic fever (see page 1765)—a childhood illness that sometimes occurs after untreated strep throat or scarlet fever—used to be the most common cause of mitral regurgitation. But today, rheumatic fever is rare in North America, Australasia, Western Europe, and other regions where antibiotics are widely used to treat infections such as strep throat. In these regions, rheumatic fever is a common cause of mitral regurgitation only among older people who did not have the benefit of antibiotics during their youth and among people who have moved from regions where antibiotics are not widely used. In such regions, rheumatic fever is still common and still commonly causes mitral stenosis or regurgitation, sometimes 10 years or more after the initial infection. Repeated attacks of rheumatic fever hasten valve deterioration.
In North America, Western Europe, and Australasia, a more common cause of mitral regurgitation is a heart attack. A heart attack can damage the structures that support the mitral valve. Another common cause is myxomatous degeneration, a hereditary connective tissue disorder that causes weakness in the tissue of the valve. As a result, the heart valve gradually becomes floppy and does not close properly.
Symptoms
Mild mitral regurgitation may not produce any symptoms. When regurgitation is more severe or when there is atrial fibrillation, people may have palpitations (an awareness that their heart beat has changed rhythm) or unexplained shortness of breath. People with heart failure may have cough, shortness of breath during exertion or at rest, and swelling in the legs.
Diagnosis
Mitral regurgitation is usually diagnosed based on the characteristic heart murmur heard through a stethoscope. The murmur is a distinctive sound produced by blood leaking backward into the left atrium when the left ventricle contracts. The disorder is sometimes diagnosed when a doctor hears this murmur during a routine physical examination.
Electrocardiography (ECG) and chest x-rays show that the left ventricle is enlarged. If mitral regurgitation is severe, the chest x-ray may also show fluid accumulation in the lungs. Echocardiography (see page 328), which uses ultrasound waves to produce an image of the heart structures and blood flow, provides the most information. This procedure can show the size of the atrium and ventricle and the amount of blood leaking, so that the severity of the regurgitation can be determined.
Treatment
If regurgitation is mild, no specific treatment may be required; however, the person may need to be evaluated periodically and may need to take antibiotics before dental and medical procedures. More serious regurgitation may be treated with an angiotensin-converting enzyme (ACE) inhibitor, such as enalapril or lisinopril, with or without digoxin. Sometimes surgery is necessary for those with severe regurgitation.
Surgery must be performed before the left ventricle becomes irreversibly weakened. Therefore, echocardiography is usually performed periodically to determine how rapidly the left ventricle is enlarging. Surgery may involve repairing the valve or replacing it with an artificial (prosthetic) valve. Repairing the valve eliminates regurgitation or reduces it enough to make the symptoms tolerable and prevent damage to the heart. Repairing the valve is preferable to replacing it, if possible, because a repaired valve usually functions better than a mechanical or bio-prosthetic valve and the person does not require lifetime anticoagulation therapy. Replacing the valve eliminates regurgitation.
Damaged heart valves are susceptible to a serious infection by bacteria (infective endocarditis). People with a damaged or an artificial valve should take antibiotics before surgical, dental, or medical procedures (see box on page 388) to reduce the risk of an infection on a valve, even though this risk is small. Atrial fibrillation, if present, may require treatment (see page 371), including use of anticoagulants to prevent clots.
Mitral Valve Prolapse
Mitral valve prolapse (MVP) is a disorder in which the valve cusps bulge into the left atrium when the left ventricle contracts, sometimes allowing leakage (regurgitation) of small amounts of blood into the atrium.
Mitral valve prolapse is often the result of a connective tissue disorder.
Most people have no symptoms, but some people have chest pain, a rapid pulse, awareness of heartbeats, migraine headaches, fatigue, and dizziness.
Doctors make the diagnosis after hearing a characteristic clicking sound through a stethoscope placed over the heart, but they may need echocardiography to confirm the diagnosis.
Most people do not need treatment.
About 2 to 5% of people have mitral valve prolapse. The cause is redundancy of the valve tissue often from myxomatous degeneration, a hereditary connective tissue disorder that causes weakness in the tissue of the valve. It causes serious heart problems only if the regurgitation becomes severe, infection of the valve occurs, or myxomatous tissue ruptures.
Replacing a Heart Valve
A damaged heart valve may be replaced with a mechanical valve made of plastic and metal or with a bio-prosthetic 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 rarely requires the 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 how old the person is, what the person’s activity level is, how well the heart is working, and which heart valve is damaged.
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.
Symptoms and Diagnosis
Most people with mitral valve prolapse have no symptoms. Others have symptoms that are difficult to explain on the basis of the mechanical problem alone; these symptoms include chest pain, a rapid pulse, palpitations (awareness of heartbeats), migraine headaches, fatigue, and dizziness. In some people, blood pressure may fall below normal when they stand up (a disorder called orthostatic hypotension).
Doctors diagnose mitral valve prolapse after hearing the characteristic clicking sound through a stethoscope. Regurgitation is diagnosed if a murmur is heard when the left ventricle contracts. Echocardiography (see page 328) enables doctors to view the prolapse and determine the severity of regurgitation if present.
Treatment
Most people with mitral valve prolapse do not need treatment. If the heart is beating too fast, a beta-blocker may be taken to slow the heart rate and to reduce palpitations and other symptoms.
If regurgitation is also present, antibiotics should be taken before surgical, dental, or medical procedures (see box on page 388) because bacterial infection of the heart valve (infective endocarditis) is a risk, although a small one.
Mitral Stenosis
Mitral stenosis (mitral valve stenosis) is a narrowing of the mitral valve opening that increases resistance to blood flow from the left atrium to the left ventricle.
Mitral stenosis usually results from rheumatic fever, but infants can be born with the condition.
Mitral stenosis does not usually cause symptoms unless it is severe.
Doctors make the diagnosis after hearing a characteristic heart murmur through a stethoscope placed over the heart.
Treatment includes use of diuretics and beta-blockers or calcium channel blockers.
In mitral stenosis, blood flow through the narrowed valve opening is reduced. As a result, the volume and pressure of blood in the left atrium increases, and the left atrium enlarges. The enlarged left atrium often beats rapidly in an irregular pattern (a disorder called atrial fibrillation). As a result, the heart’s pumping efficiency is reduced. If mitral stenosis is severe, pressure increases in the blood vessels of the lungs, resulting in heart failure with fluid accumulation in the lungs and a low level of oxygen in the blood. If a woman with severe mitral stenosis becomes pregnant, heart failure may develop rapidly.
Cause
Mitral stenosis almost always results from rheumatic fever, a childhood illness that sometimes occurs after untreated strep throat or scarlet fever (see page 1765). Rheumatic fever is now rare in North America, Australasia, and Western Europe because antibiotics are widely used to treat infection. Thus, in these regions, mitral stenosis occurs mostly in older people who had rheumatic fever and who did not have the benefit of antibiotics during their youth or in people who have moved from regions where antibiotics are not widely used. In such regions, rheumatic fever is common, and it leads to mitral stenosis in adults, teenagers, and sometimes even children. Typically, when rheumatic fever is the cause of mitral stenosis, the mitral valve cusps are partially fused together.
Mitral stenosis can rarely be present at birth (congenital). Infants born with the disorder rarely live beyond age 2, unless they have surgery.
Three rare conditions unrelated to mitral stenosis can produce the same effects as the stenosis. They include a myxoma (a noncancerous tumor in the left atrium), cor triatriatum (a rare developmental abnormality in which a membrane goes across the left atrium), and pulmonary veno-occlusive disease (a narrowing of the veins that lead from the lungs into the left atrium).
Symptoms and Diagnosis
Mild mitral stenosis does not usually cause symptoms. Some people with more severe mitral stenosis have atrial fibrillation or heart failure. People with atrial fibrillation may feel palpitations (awareness of heartbeats). People with heart failure become easily fatigued and short of breath. Shortness of breath may occur only during physical activity at first, but later, it may occur even during rest. Some people can breathe comfortably only when they are propped up with pillows or sitting upright. Those people with a low level of oxygen in the blood and high blood pressure in the lungs may have a plum-colored flush in the cheeks (called mitral facies). People may cough up blood (hemoptysis) if the high pressure causes a vein or capillaries in the lungs to burst. The resulting bleeding into the lungs is usually slight, but if hemoptysis occurs, the person should be evaluated by a doctor promptly because hemoptysis indicates severe mitral stenosis or another serious problem.
With a stethoscope, doctors may hear the characteristic heart murmur as blood tries to pass through the narrowed valve opening from the left atrium into the left ventricle. Unlike a normal valve, which opens silently, the abnormal valve often makes a snapping sound as it opens to allow blood into the left ventricle. The diagnosis is usually confirmed by electrocardiography (ECG), a chest x-ray showing an enlarged atrium, and echocardiography, which uses ultrasound waves to produce an image of the narrowed valve and the blood passing through it.
Prevention and Treatment
Mitral stenosis will not occur if rheumatic fever is prevented by promptly treating strep throat with antibiotics.
Treatment includes use of diuretics and beta-blockers or calcium channel blockers. Diuretics, which increase urine formation, can reduce blood pressure in the lungs by reducing the volume of circulating blood. Beta-blockers, digoxin, and calcium channel blockers help control heart rhythms. Anticoagulants may be needed to prevent clot formation in people with atrial fibrillation.
If drug therapy does not reduce the symptoms satisfactorily, the valve may be repaired or replaced. Sometimes the valve can be stretched open using a procedure called balloon valvuloplasty. In this procedure, a balloon-tipped catheter is threaded through a vein and eventually into the heart (see page 330). Once inside the valve, the balloon is inflated, separating the valve cusps. Alternatively, heart surgery may be performed to separate the fused cusps. If the valve is too badly damaged, it may be surgically replaced with an artificial valve.
People with mitral stenosis are given antibiotics before a surgical, dental, or medical procedure (see box on page 388) to reduce the small risk of developing a heart valve infection (infective endocarditis).
Aortic Regurgitation
Aortic regurgitation (aortic incompetence, aortic insufficiency) is leakage of blood back through the aortic valve each time the left ventricle relaxes.
Rheumatic fever and syphilis are the most common causes.
Aortic regurgitation causes no symptoms unless heart failure develops.
Doctors suspect the diagnosis because of physical examination findings, and they use echocardiography to confirm the diagnosis.
The damaged heart valve must be replaced surgically.
As the left ventricle relaxes to fill with blood from the left atrium, blood leaks backward from the aorta into the left ventricle, increasing the volume and pressure of blood in the left ventricle. As a result, the amount of work the heart has to do increases. To compensate, the muscular walls of the ventricles thicken (hypertrophy), and the chambers of the ventricles enlarge (dilate). Eventually, despite this compensation, the heart may be unable to meet the body’s need for blood, leading to heart failure, with fluid accumulation in the lungs.
Cause
Rheumatic fever and syphilis used to be the most common causes of aortic regurgitation in North America, Australasia, and Western Europe, where both disorders are now rare because of the widespread use of antibiotics. In regions where antibiotics are not widely used, aortic regurgitation due to rheumatic fever or syphilis is still common. Aside from these infections, the most common causes of severe aortic regurgitation are weakening of the valve’s usually tough, fibrous tissue due to myxomatous degeneration (a hereditary connective tissue disorder in which the valve gradually becomes floppy); degeneration of the valve due to unknown factors; aortic aneurysms; and aortic dissection. Common causes of mild aortic regurgitation are severe high blood pressure and a birth defect in which the aortic valve consists of two cusps (bicuspid valve) instead of the usual three (tricuspid valve). About 2% of boys and 1% of girls are born with this defect. Other causes of aortic regurgitation include bacterial infection of the valve (infective endocarditis) and injury.
Symptoms and Diagnosis
Mild aortic regurgitation produces no symptoms other than a characteristic heart murmur that can be heard with a stethoscope each time the left ventricle relaxes. People with severe regurgitation may develop symptoms when heart failure results. Heart failure causes shortness of breath during exertion. Lying flat, especially at night, makes breathing difficult. Sitting up allows backed-up fluid to drain out of the upper part of the lungs, restoring normal breathing. About 5% of people with aortic regurgitation have chest pain due to an inadequate blood supply to the heart muscle (angina), especially at night.
The pulse, sometimes called a collapsing pulse, is momentarily strong, then disappears quickly because the blood leaks backward through the aortic valve, causing blood pressure to decrease sharply.
Doctors usually suspect the diagnosis based on the results of a physical examination (such as the collapsing pulse and characteristic heart murmur) and an enlarged heart seen on an x-ray. Electrocardiography (ECG) may show signs of an enlarged left ventricle. Echocardiography can show the faulty valve and help doctors determine how severe regurgitation is and whether heart valve replacement surgery is needed. Coronary angiography is performed in older people before surgery because about 20% of people with aortic regurgitation also have coronary artery disease.
Treatment
Unless aortic regurgitation is mild, surgery is ultimately almost always required. Drug treatment is not especially effective in slowing the progression of heart failure and does not eliminate the need for timely valve replacement, but various drugs may be used to control symptoms prior to surgery. The damaged valve should be surgically replaced with an artificial valve before the left ventricle becomes irreversibly damaged and heart failure becomes too severe. Usually, echocardiography is performed periodically to determine how rapidly the left ventricle is enlarging, so that surgery can be scheduled at an appropriate time.
People with aortic regurgitation, even when mild, are given antibiotics before surgical, dental, or medical procedures (see box on page 388) to reduce the risk of infection of the damaged heart valve.
Aortic Stenosis
Aortic stenosis is a narrowing of the aortic valve opening that increases resistance to blood flow from the left ventricle to the aorta.
The most common cause in people younger than 70 is a congenital abnormality of the valve. In people over 70, the most common cause is aortic sclerosis.
People may have chest pain or feel short of breath or faint.
Doctors usually base the diagnosis on a characteristic heart murmur heard through a stethoscope, on pulse abnormalities, and on results of echocardiography.
People see their doctors regularly so their condition can be monitored, and people with symptoms may undergo surgical replacement of the valve.
In aortic stenosis, the wall of the left ventricle usually thickens because the ventricle must work harder to pump blood through the narrowed valve opening into the aorta. The thickened heart muscle requires an increasing supply of blood from the coronary arteries, and sometimes, especially during exercise, the blood supply does not meet the needs of the heart muscle, and chest pain, fainting, and sometimes sudden death may occur. The heart muscle may also begin to weaken, leading to heart failure. The abnormal aortic valve can rarely become infected by bacteria (infective endocarditis).
Cause
In North America, Australasia, and Western Europe, aortic stenosis is mainly a disease of older people—the result of scarring and calcium accumulation (calcification) in the valve cusps. In such cases, aortic stenosis begins after age 60 but does not usually produce symptoms until age 70 or 80. Aortic stenosis may also result from rheumatic fever contracted in childhood. When rheumatic fever is the cause, aortic stenosis is usually accompanied by mitral stenosis, leakage (regurgitation), or both.
In younger people, the most common cause is a birth defect, such as a valve with only two cusps instead of the usual three or a valve with an abnormal funnel shape (see page 1715). The narrowed aortic valve opening may not be a problem in infancy, but problems occur as a person grows. The valve opening remains the same size, but the heart grows and enlarges further as it tries to pump increasing amounts of blood through the small valve opening. Over the years, the opening of a defective valve often becomes stiff and narrow because calcium accumulates.
Symptoms and Diagnosis
Chest pain (angina) may occur during exertion. This pain goes away with several minutes of rest. People with heart failure develop fatigue and shortness of breath during exertion.
People who have severe aortic stenosis may faint during exertion because blood pressure may fall suddenly. Fainting usually occurs without any warning symptoms (such as dizziness or light-headedness) or with any symptoms after awakening.
Doctors usually base the diagnosis on a characteristic heart murmur heard through a stethoscope, on pulse abnormalities, and on results of electrocardiography (ECG) indicating thickening of the heart wall. For people who experience angina, shortness of breath, or faintness, echocardiography (see page 328) is the best procedure for assessing the severity of aortic stenosis (by measuring how small the valve opening is) and the function of the left ventricle. Cardiac catheterization (see page 330) is usually necessary as the doctor is not sure whether the person also has coronary artery disease.
SPOTLIGHT ON AGING
Sometimes calcium accumulates on the aortic valve, and the valve thickens. But the thickening does not interfere with blood flow through the valve. This disorder is called aortic sclerosis. About 1 out of 4 people over 65 have this disorder.
Aortic sclerosis does not cause symptoms. It may cause a soft heart murmur, heard by a doctor through a stethoscope. Aortic sclerosis may not make a person feel any different, but it increases the risk of a heart attack and death. Consequently, identifying and eliminating or controlling risk factors for coronary artery disease are important for people with aortic sclerosis. These risk factors include smoking, high blood pressure, abnormal cholesterol and triglyceride levels, and diabetes.
Treatment
Adults who have aortic stenosis but no symptoms should see their doctor regularly and should avoid overly stressful exercise. Echocardiography is performed periodically to monitor heart and valve function.
In adults who have aortic stenosis that causes shortness of breath on exertion, angina, or fainting, the aortic valve is surgically replaced, preferably before the left ventricle is irreversibly damaged. Echocardiography, usually performed periodically, can help doctors determine when to schedule surgery. Surgical replacement of the abnormal valve is the best treatment for adults of all ages, and the prognosis after valve replacement is excellent.
Before surgery, heart failure is treated with diuretics (see page 359). Treating angina is often difficult, because nitroglycerin, which is used to treat angina in people who have coronary artery disease, can rarely cause dangerously low blood pressure and worsen the angina in people with aortic stenosis.
People with an artificial valve must take antibiotics before a surgical, dental, or medical procedure (see box on page 388) to reduce the risk of an infection on the valve (infective endocarditis).
For children who have severe stenosis, surgery may be performed even before symptoms develop, because sudden death may occur before symptoms develop. Safe, effective alternatives to valve replacement are surgical repair of the valve and balloon valvuloplasty. In balloon valvuloplasty, a balloon-tipped catheter is threaded through a vein and eventually into the heart (see page 330). Once inside the valve, the balloon is inflated to expand the valve opening. However, later, when children are fully grown, the valve usually must be replaced. In adults, stenosis always recurs after balloon valvuloplasty; so among adults, this procedure is used only for frail older people who cannot tolerate surgery.
Tricuspid Regurgitation
Tricuspid regurgitation (tricuspid incompetence, tricuspid insufficiency) is leakage of blood backward through the tricuspid valve each time the right ventricle contracts.
Tricuspid regurgitation is caused by disorders that enlarge the right ventricle.
Symptoms are vague, such as weakness and fatigue.
Doctors suspect the diagnosis because of physical examination findings, and they use echocardiography to confirm the diagnosis.
The underlying disorder needs to be treated.
As the right ventricle contracts to pump blood forward to the lungs, some blood leaks backward into the right atrium, increasing the volume of blood there and resulting in less blood being pumped through the heart and to the body. As a result, the right atrium enlarges, and blood pressure increases in the right atrium and the large veins that enter it from the body. The liver may swell because of this increased pressure. Enlargement of the right atrium also can result in atrial fibrillation, a rapid, irregular heartbeat. Eventually, heart failure develops.
Cause
Tricuspid regurgitation usually results when the right ventricle enlarges and resistance to blood flow from the right ventricle to the lungs is increased. Resistance may be increased by a severe, longstanding lung disorder, such as emphysema or pulmonary hypertension, by disorders involving the left side of the heart, or rarely by narrowing of the pulmonary valve (pulmonic stenosis). To compensate, the right ventricle enlarges, stretching the tricuspid valve and causing regurgitation.
Other, less common causes are infection of the heart valves (infective endocarditis most often due to intravenous injection of illicit drugs), use of fenfluramine (no longer available), birth defects of the tricuspid valve, injury, and myxomatous degeneration (a hereditary disorder in which the valve gradually becomes floppy).
Symptoms and Diagnosis
Tricuspid regurgitation can cause vague symptoms, such as weakness and fatigue. They develop because the heart is pumping a smaller amount of blood. Usually, the only other symptoms are pulsations in the neck from the elevated right atrial pressure and discomfort in the right upper part of the abdomen due to an enlarged liver. Heart failure results in accumulation of fluid in the body, mainly in the legs.
The diagnosis is based on the person’s medical history and results of a physical examination, electrocardiography (ECG), and chest x-ray. Through a stethoscope, doctors may hear a characteristic murmur produced by the blood leaking backward through the tricuspid valve, but the murmur tends to disappear as the regurgitation worsens. Echocardiography (see page 328) can produce an image of the leaky valve and the amount of blood leaking, so that the severity of the regurgitation can be determined.
Treatment
Usually, mild tricuspid regurgitation requires little or no treatment. However, the underlying disorder, such as emphysema, pulmonary hypertension, pulmonic stenosis, or abnormalities of the left side of the heart, is likely to require treatment. Treatment of atrial fibrillation and heart failure is also necessary, but surgery to repair the tricuspid valve is rarely done unless surgery on another heart valve (for example, mitral valve replacement) is also needed.
Tricuspid Stenosis
Tricuspid stenosis is a narrowing of the tricuspid valve opening that increases resistance to blood flow from the right atrium to the right ventricle.
Over many years, the right atrium enlarges because blood flow through the narrowed valve opening is partially blocked, increasing the volume of blood in the atrium. In turn, this increased volume causes an increase in pressure in the veins bringing blood back to the heart from the body (except the lungs). However, the right ventricle shrinks, because the amount of blood entering it from the right atrium is reduced. Tricuspid regurgitation rarely occurs.
Nearly all cases are caused by rheumatic fever, which has become rare in North America, Australasia, and Western Europe. Rarely, the cause is a tumor in the right atrium, a connective tissue disorder, or, even more rarely, a birth defect of the heart.
Symptoms are usually mild. They include palpitations (awareness of heartbeats), a fluttering discomfort in the neck, cold skin, and fatigue. Abdominal discomfort may result if the increased pressure in the veins causes the liver to enlarge.
Through a stethoscope, doctors may hear the characteristic murmur of tricuspid stenosis. A chest x-ray shows that the right atrium is enlarged. Echocardiography (see page 328) can produce an image of the narrowed valve opening and show the amount of blood passing through the valve, so that the severity of the stenosis can be determined. Electrocardiography (ECG—see page 326) shows changes indicating that the right atrium is strained. Tricuspid stenosis is rarely severe enough to require surgical repair.
Pulmonic Stenosis
Pulmonic (pulmonary) stenosis is a narrowing of the pulmonary valve opening that increases resistance to blood flow from the right ventricle to the pulmonary artery. It is often present at birth (congenital) and thus affects children.
Pulmonic stenosis, which is rare among adults, is usually due to a birth defect (see page 1716). When the stenosis is severe, it is usually diagnosed during childhood, because it produces a loud heart murmur. Severe pulmonic stenosis occasionally causes heart failure in children but often does not produce symptoms until adulthood. Symptoms include chest pain (angina), shortness of breath, and fainting.
Young children with this disorder often require heart surgery. In adults and older children, balloon valvuloplasty may be done. In this procedure, the valve is stretched open using a balloon-tipped catheter threaded through a vein and eventually into the heart. Once inside the valve, the balloon is inflated, separating the valve cusps.