Valvular heart disease
Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart. These conditions occur largely as a consequence of aging, but may also be the result of congenital abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.
Anatomically, the valves are part of the dense connective tissue of the heart known as the cardiac skeleton and are responsible for the regulation of blood flow through the heart and great vessels. Valve failure or dysfunction can result in diminished heart functionality, though the particular consequences are dependent on the type and severity of valvular disease. Treatment of damaged valves may involve medication alone, but often involves surgical valve repair or replacement.
Classification
Stenosis and insufficiency/regurgitation represent the dominant functional and anatomic consequences associated with valvular heart disease. Irrespective of disease process, alterations to the valve occur that produce one or a combination of these conditions. Insufficiency and regurgitation are synonymous terms that describe an inability of the valve to prevent backflow of blood as leaflets of the valve fail to join correctly. Stenosis is characterized by a narrowing of the valvular orifice that prevents adequate outflow of blood. Stenosis can also result in insufficiency if thickening of the annulus or leaflets results in inappropriate leaf closure.| Valve involved | Stenotic disease | Insufficiency/regurgitation disease |
| Aortic valve | Aortic valve stenosis | Aortic insufficiency/regurgitation |
| Mitral valve | Mitral valve stenosis | Mitral insufficiency/regurgitation |
| Tricuspid valve | Tricuspid valve stenosis | Tricuspid insufficiency/regurgitation |
| Pulmonary valve | Pulmonary valve stenosis | Pulmonary insufficiency/regurgitation |
Aortic and mitral valve disorders
Aortic and mitral valve disease are termed left heart diseases. Diseases of these valves are more prevalent than disease of the pulmonary or tricuspid valve due to the higher pressures the left heart experiences.Stenosis of the aortic valve is characterized by a thickening of the valvular annulus or leaflets that limits the ability of blood to be ejected from the left ventricle into the aorta. Stenosis is typically the result of valvular calcification but may be the result of a congenitally malformed bicuspid aortic valve. This defect is characterized by the presence of only two valve leaflets. It may occur in isolation or in concert with other cardiac anomalies.
Aortic insufficiency, or regurgitation, is characterized by an inability of the valve leaflets to appropriately close at end systole, thus allowing blood to flow inappropriately backwards into the left ventricle. Causes of aortic insufficiency in the majority of cases are unknown, or idiopathic. It may be the result of connective tissue or immune disorders, such as Marfan syndrome or systemic lupus erythematosus, respectively. Processes that lead to aortic insufficiency usually involve dilation of the valve annulus, thus displacing the valve leaflets, which are anchored in the annulus.
Mitral stenosis is caused largely by rheumatic heart disease, though is rarely the result of calcification. In some cases vegetations form on the mitral leaflets as a result of endocarditis, an inflammation of the heart tissue. Mitral stenosis is uncommon and not as age-dependent as other types of valvular disease.
Mitral insufficiency can be caused by dilation of the left heart, often a consequence of heart failure. In these cases the left ventricle of the heart becomes enlarged and causes displacement of the attached papillary muscles, which control the mitral valve.
Pulmonary and tricuspid valve disorders
Pulmonary and tricuspid valve diseases are right heart diseases. Pulmonary valve diseases are the least common heart valve disease in adults.Pulmonary valve stenosis is often the result of congenital malformations and is observed in isolation or as part of a larger pathologic process, as in Tetralogy of Fallot, Noonan syndrome, and congenital rubella syndrome. Unless the degree of stenosis is severe individuals with pulmonary stenosis usually have excellent outcomes and treatment options. Often patients do not require intervention until later in adulthood as a consequence of calcification that occurs with aging.
Pulmonary valve insufficiency occurs commonly in healthy individuals to a very mild extent and does not require intervention. More appreciable insufficiency it is typically the result of damage to the valve due to cardiac catheterization, intra-aortic balloon pump insertion, or other surgical manipulations. Additionally, insufficiency may be the result of carcinoid syndrome, inflammatory processes such a rheumatoid disease or endocarditis, or congenital malformations. It may also be secondary to severe pulmonary hypertension.
Tricuspid valve stenosis without co-occurrent regurgitation is highly uncommon and typically the result of rheumatic disease. It may also be the result of congenital abnormalities, carcinoid syndrome, obstructive right atrial tumors, or hypereosinophilic syndromes.
Minor tricuspid insufficiency is common in healthy individuals. In more severe cases it is a consequence of dilation of the right ventricle, leading to displacement of the papillary muscles which control the valve's ability to close. Dilation of the right ventricle occurs secondary to ventricular septal defects, right to left shunting of blood, eisenmenger syndrome, hyperthyroidism, and pulmonary stenosis. Tricuspid insufficiency may also be the result of congenital defects of the tricuspid valve, such as Ebstein's anomaly.
Signs and symptoms
Aortic stenosis
Symptoms of aortic stenosis may include heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, angina pectoris, and syncope, usually exertional.Medical signs of aortic stenosis include pulsus parvus et tardus, that is, diminished and delayed carotid pulse, fourth heart sound, decreased A2 sound, sustained apex beat, precordial thrill. Auscultation may reveal a systolic murmur of a harsh crescendo-decrescendo type, heard in 2nd right intercostal space and radiating to the carotid arteries.
Aortic regurgitation
Patients with aortic regurgitation may experience heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, and angina pectoris. In acute cases patients may experience cyanosis and circulatory shock.Medical signs of aortic regurgitation include increased pulse pressure by increased systolic and decreased diastolic blood pressure, but these findings may not be significant if acute. The patient may have a diastolic decrescendo murmur best heard at left sternal border, water hammer pulse, Austin Flint murmur, and a displaced apex beat down and to the left. A third heart sound may be present
Mitral stenosis
Patients with mitral stenosis may present with heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, chest pain, hemoptysis, thromboembolism, or ascites and edema. Symptoms of mitral stenosis increase with exercise and pregnancyOn auscultation of a patient with mitral stenosis, typically the most prominent sign is a loud S1. Another finding is an opening snap followed by a low-pitched diastolic rumble with presystolic accentuation. The opening snap follows closer to the S2 heart tone with worsening stenosis. The murmur is heard best with the bell of the stethoscope lying on the left side and its duration increases with worsening disease. Advanced disease may present with signs of right-sided heart failure such as parasternal heave, jugular venous distension, hepatomegaly, ascites and/or pulmonary hypertension. Signs increase with exercise and pregnancy.
Mitral regurgitation
Patients with mitral regurgitation may present with heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, or pulmonary edema.On auscultation of a patient with mitral stenosis, there may be a holosystolic murmur at the apex, radiating to the back or clavicular area, a third heart sound, and a loud, palpable P2, heard best when lying on the left side. Patients also commonly have atrial fibrillation. Patients may have a laterally displaced apex beat, often with heave In acute cases, the murmur and tachycardia may be only distinctive signs.
Tricuspid regurgitation
Patients with tricuspid regurgitation may experience symptoms of right-sided heart failure, such as ascites, hepatomegaly, edema and jugular venous distension.Signs of tricuspid regurgitation include pulsatile liver, prominent V waves and rapid y descents in jugular venous pressure. Auscultatory findings include inspiratory third heart sound at left lower sternal border and a blowing holosystolic murmur at LLSB, intensifying with inspiration, and decreasing with expiration and Valsalva maneuver. Patients may have a parasternal heave along LLSB. Atrial fibrillation is usually present in patients with tricuspid regurgitation
Diagnosis
Aortic stenosis
Patients with aortic stenosis can have chest X-ray findings showing dilation of the ascending aorta, but they may also have a completely normal chest X-ray. Direct visualization of calcifications on chest X-ray is uncommon. Other findings include dilation of the left ventricle. ECG typically shows left ventricular hypertrophy in patients with severe stenosis, but it may also show signs of left heart strain. Echocardiography is the diagnostic gold standard, which shows left ventricular hypertrophy, leaflet calcification, and abnormal leaflet closure.| Classification | Valve area |
| Mild aortic stenosis | <1 cm2 |
| Moderate aortic stenosis | 1.0-1.5 cm2 |
| Severe aortic stenosis | 1.5-2.0 cm2 |
Aortic regurgitation
is not as sensitive as other tests, but it may show aortic root dilation and apex displacement. ECG may show left ventricular hypertrophy and signs of left heart strain. Left axis deviation can be a sign of advanced disease. Echocardiogram can be helpful in determining the root cause of the disease, as it will clearly show aortic root dilation or dissection if it exists. Typically the pump function of the heart during systole is normal, but echocardiogram will show flow reversal during diastole. This disease is classified using regurgitant fraction, or the amount of volume that flows back through the valve divided by the total forward flow through the valve during systole. Severe disease has a RF of >50%, while progressive aortic regurgitation has an RF of 30–49%.Mitral stenosis
in mitral stenosis will typically show an enlarged left atrium, and may show dilation of the pulmonary veins. ECG can show left atrial enlargement, due to increased pressures in the left atrium. Echocardiography is helpful in determining the severity of the disease by estimating the pulmonary artery systolic pressure. This test can also show leaflet calcification and the pressure gradient over the mitral valve. Severe mitral stenosis is defined as a mitral valve area <1.5 cm2. Progressive mitral stenosis has a normal valve area but will have increased flow velocity across the mitral valve.Mitral regurgitation
in mitral regurgitation can show an enlarged left atrium, as well as pulmonary venous congestion. It may also show valvular calcifications specifically in combined mitral regurgitation and stenosis due to rheumatic heart disease. ECG typically shows left atrial enlargement, but can also show right atrial enlargement if the disease is severe enough to cause pulmonary hypertension. Echocardiography is useful in visualizing the regurgitant flow and calculating the RF. It can also be used to determine the degree of calcification, and the function and closure of the valve leaflets. Severe disease has an RF of >50%, while progressive mitral regurgitation has an RF of <50%.Causes and risk factors
Calcific disease
of the leaflets of the aortic valve is a common with increasing age, but the mechanism is likely to be more related to increased lipoprotein deposits and inflammation than the "wear and tear" of advance age. Aortic stenosis due to calcification of tricuspid aortic valve with age comprises >50% of the disease. Aortic stenosis due to calcification of a bicuspid aortic valve comprises about 30-40% of the disease. Hypertension, diabetes mellitus, hyperlipoproteinemia and uremia may speed up the process of valvular calcification.Dysplasia
is an error in the development of any of the heart valves, and a common cause of congenital heart defects in humans as well as animals; tetralogy of Fallot is a congenital heart defect with four abnormalities, one of which is stenosis of the pulmonary valve. Ebstein's anomaly is an abnormality of the tricuspid valve, and its presence can lead to tricuspid valve regurgitation. A bicuspid aortic valve is an aortic valve with only 2 cusps as opposed to the normal 3. It is present in about 0.5% to 2% of the general population, and causes increased calcification due to higher turbulent flow through the valve.Connective tissue disorders
is a connective tissue disorder that can lead to chronic aortic or mitral regurgitation. Osteogenesis imperfecta is a disorder in formation of type I collagen and can also lead to chronic aortic regurgitation.Inflammatory disorders
Inflammation of the heart valves due to any cause is called valvular endocarditis; this is usually due to bacterial infection but may also be due to cancer, certain autoimmune conditions and hypereosinophilic syndrome. Endocarditis of the valves can lead to regurgitation through that valve, which is seen in the tricuspid, mitral, and aortic valves. Certain medications have been associated with valvular heart disease, most prominently ergotamine derivatives pergolide and cabergoline.Valvular heart disease resulting from rheumatic fever is referred to as rheumatic heart disease. Damage to the heart valves follows infection with beta-hemolytic bacteria, such as typically of the respiratory tract. Pathogenesis is dependent on cross reaction of M proteins produced by bacteria with the myocardium. This results in generalized inflammation in the heart, this manifests in the mitral valve as vegetations, and thickening or fusion of the leaflets, leading to a severely compromised buttonhole valve.
Rheumatic heart disease typically only involves the mitral valve, though in some cases the aortic and mitral valves are both involved. Involvement of other heart valves without damage to the mitral are exceedingly rare.Mitral stenosis is almost always caused by rheumatic heart disease Less than 10% of aortic stenosis is caused by rheumatic heart disease. Rheumatic fever can also cause chronic mitral and aortic regurgitation.
While developed countries once had a significant burden of rheumatic fever and rheumatic heart disease, medical advances and improved social conditions have dramatically reduced their incidence. Many developing countries, as well as indigenous populations within developed countries, still carry a significant burden of rheumatic fever and rheumatic heart disease and there has been a resurgence in efforts to eradicate the diseases in these populations.
Diseases of the aortic root can cause chronic aortic regurgitation. These diseases include syphilitic aortitis, Behçet's disease, and reactive arthritis
Heart disease
Tricuspid regurgitation is usually secondary to right ventricular dilation which may be due to left ventricular failure, right ventricular infarction, inferior myocardial infarction, or cor pulmonale Other causes of tricuspid regurgitation include carcinoid syndrome and myxomatous degeneration.Special populations
Pregnancy
The evaluation of individuals with valvular heart disease who are or wish to become pregnant is a difficult issue. Issues that have to be addressed include the risks during pregnancy to the mother and the developing fetus by the presence of maternal valvular heart disease as a pre-existing disease in pregnancy.Normal physiological changes during pregnancy require, on average, a 50% increase in circulating blood volume that is accompanied by an increase in cardiac output that usually peaks between the midportion of the second and third trimesters. The increased cardiac output is due to an increase in the stroke volume, and a small increase in heart rate, averaging 10 to 20 beats per minute. Additionally uterine circulation and endogenous hormones cause systemic vascular resistance to decrease and a disproportionately lowering of diastolic blood pressure causes a wide pulse pressure. Inferior vena caval
obstruction from a gravid uterus in the supine position can result in an abrupt decrease in cardiac preload, which leads to hypotension with weakness and lightheadedness. During labor and delivery cardiac output increases more in part due to the associated anxiety and pain, as well as due to uterine contractions which will cause an increases in systolic and diastolic blood pressure.
Valvular heart lesions associated with high maternal and fetal risk during pregnancy include:
- Severe aortic stenosis with or without symptoms
- Aortic regurgitation with NYHA functional class III-IV symptoms
- Mitral stenosis with NYHA functional class II-IV symptoms
- Mitral regurgitation with NYHA functional class III-IV symptoms
- Aortic and/or mitral valve disease resulting in severe pulmonary hypertension
- Aortic and/or mitral valve disease with severe LV dysfunction
- Mechanical prosthetic valve requiring anticoagulation
- Marfan syndrome with or without aortic regurgitation
Treatment
Some of the most common treatments of valvular heart disease are avoiding smoking and excessive alcohol consumption, antibiotics, antithrombotic medications such as aspirin, anticoagulants, balloon dilation, and water pills.In some cases, surgery may be necessary.