Valvular heart disease

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Valvular_heart_disease

 

Valvular heart disease
Specialty	Cardiology

This diagram shows the valves of the heart. The aortic and mitral valves are shown in the left heart, and the tricuspid and pulmonic valves are shown in the right heart.

Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) 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 (valvuloplasty) or replacement (insertion of an artificial heart valve).

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 (coapt) 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 (typically lipomas or myxomas), 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 (most frequent symptom), 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 (if right-sided heart failure develops). Symptoms of mitral stenosis increase with exercise and pregnancy.

On 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 (presenting with a loud P₂). 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 (LLSB) 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

ECG showing left ventricular hypertrophy, these findings may be present in 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.

Diagnostic classification of aortic stenosis

Classification	Valve area
Mild aortic stenosis	<1 cm="" sup="">2

Moderate aortic stenosis 1.0-1.5 cm² Severe aortic stenosis 1.5-2.0 cm²

Aortic regurgitation

Chest x-ray is not as sensitive as other tests, but it may show aortic root dilation (especially in causes involving the aortic root) 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 (RF), 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

Chest x-ray 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="" cm="" sup="">2

. Progressive mitral stenosis has a normal valve area but will have increased flow velocity across the mitral valve.

Mitral regurgitation

Chest x-ray 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 p="">

Causes and risk factors

Calcific disease

Calcification 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

Heart valve 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

Marfan's Syndrome 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 (marantic endocarditis), certain autoimmune conditions (Libman-Sacks endocarditis, seen in systemic lupus erythematosus) and hypereosinophilic syndrome (Loeffler endocarditis). Endocarditis of the valves can lead to regurgitation through that valve, which is seen in the tricuspid, mitral, and aortic valves.^[11] 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 (70% of cases), though in some cases the aortic and mitral valves are both involved (25%). 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 (the most common cause), 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 an intercurrent 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:

1. Severe aortic stenosis with or without symptoms
2. Aortic regurgitation with NYHA functional class III-IV symptoms
3. Mitral stenosis with NYHA functional class II-IV symptoms
4. Mitral regurgitation with NYHA functional class III-IV symptoms
5. Aortic and/or mitral valve disease resulting in severe pulmonary hypertension (pulmonary pressure greater than 75% of systemic pressures)
6. Aortic and/or mitral valve disease with severe LV dysfunction (EF less than 0.40)
7. Mechanical prosthetic valve requiring anticoagulation
8. Marfan syndrome with or without aortic regurgitation

In individuals who require an artificial heart valve, consideration must be made for deterioration of the valve over time (for bioprosthetic valves) versus the risks of blood clotting in pregnancy with mechanical valves with the resultant need of drugs in pregnancy in the form of anticoagulation.

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.

Aortic stenosis

Treatment of aortic stenosis is not necessary in asymptomatic patients, unless the stenosis is classified as severe based on valve hemodynamics. Both asymptomatic severe and symptomatic aortic stenosis are treated with aortic valve replacement (AVR) surgery. Trans-catheter Aortic Valve Replacement (TAVR) is an alternative to AVR and is recommended in high risk patients who may not be suitable for surgical AVR. Any angina is treated with short-acting nitrovasodilators, beta-blockers and/or calcium blockers. Any hypertension is treated aggressively, but caution must be taken in administering beta-blockers. Any heart failure is treated with digoxin, diuretics, nitrovasodilators and, if not contraindicated, cautious inpatient administration of ACE inhibitors. Moderate stenosis is monitored with echocardiography every 1-2 years, possibly with supplementary cardiac stress test. Severe stenosis should be monitored with echocardiography every 3-6 months.

Aortic regurgitation

Aortic regurgitation is treated with aortic valve replacement, which is recommended in patients with symptomatic severe aortic regurgitation. Aortic valve replacement is also recommended in patients that are asymptomatic but have chronic severe aortic regurgitaiton and left ventricular ejection fraction of less than 50%. Hypertension is treated in patients with chronic aortic regurgitation, with the anti-hypersensives of choice being calcium channel blockers, ACE inhibitors, or ARBs. Also, endocarditis prophylaxis is indicated before dental, gastrointestinal or genitourinary procedures. Mild to moderate aortic regurgitation should be followed with echocardiography and a cardiac stress test once every 1-2 years. In severe moderate/severe cases, patients should be followed with echocardiography and cardiac stress test and/or isotope perfusion imaging every 3–6 months.

Mitral stenosis

For patients with symptomatic severe mitral stenosis, percutaneous balloon mitral valvuloplasty (PBMV) is recommended. If this procedure fails, then it may be necessary to undergo mitral valve surgery, which may involve valve replacement, repair, or commisurotomy. Anticoagulation is recommended for patients that have mitral stenosis in the setting of atrial fibrilliation or a previous embolic event. No therapy is required for asymptomatic patients. Diuretics may be used to treat pulmonary congestion or edema.

Mitral regurgitation

Surgery is recommended for chronic severe mitral regurgitation in symptomatic patients with left ventricular ejection fraction (LVEF) of greater than 30%, and asymptomatic patients with LVEF of 30-60% or left ventricular end diastolic volume (LVEDV) > 40%. Surgical repair of the leaflets is preferred to mitral valve replacement as long as the repair is feasible. Mitral regurgitation may be treated medically with vasodilators, diuretics, digoxin, antiarrhythmics, and chronic anticoagulation. Mild to moderate mitral regurgitation should be followed with echocardiography and cardiac stress test every 1–3 years. Severe mitral regurgitation should be followed with echocardiography every 3–6 months.

Epidemiology

In the United States, about 2.5% of the population has moderate to severe valvular heart disease. The prevalence of these diseases increase with age, and 75 year-olds in the United States have a prevalence of about 13%. In industrially underdeveloped regions, rheumatic disease is the most common cause of valve diseases, and it can cause up to 65% of the valve disorders seen in these regions.

Aortic stenosis

Aortic stenosis is typically the result of aging, occurring in 12.4% of the population over 75 years of age and represents the most common cause of outflow obstruction in the left ventricle.^[1] Bicuspid aortic valves are found in up to 1% of the population, making it one of the most common cardiac abnormalities.

Aortic regurgitation

The prevalence of aortic regurgitation also increases with age. Moderate to severe disease has a prevalence of 13% in patients between the ages of 55 and 86. This valve disease is primarily caused by aortic root dilation, but infective endocarditis has been an increasing risk factor. It has been found to be the cause of aortic regurgitation in up to 25% of surgical cases.

Mitral stenosis

Mitral stenosis is caused almost exclusively by rheumatic heart disease, and has a prevalence of about 0.1% in the United States. Mitral stenosis is the most common valvular heart disease in pregnancy.

Mitral regurgitation

Mitral regurgitation is significantly associated with normal aging, rising in prevalence with age. It is estimated to be present in over 9% of people over 75.

Rheumatic fever

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Rheumatic_fever 

 

Rheumatic fever
Other names	Acute rheumatic fever (ARF)
Rheumatic heart disease at autopsy with characteristic findings (thickened mitral valve, thickened chordae tendineae, hypertrophied left ventricular myocardium).
Specialty	Cardiology
Symptoms	Fever, multiple painful joints, involuntary muscle movements, erythema marginatum
Complications	Rheumatic heart disease, heart failure, atrial fibrillation, infection of the valves
Usual onset	2–4 weeks after a streptococcal throat infection, age 5-14 years
Causes	Autoimmune disease triggered by Streptococcus pyogenes
Risk factors	Genetics, malnutrition, poverty
Diagnostic method	Based on symptoms and infection history
Prevention	Antibiotics for strep throat, improved sanitation
Treatment	Prolonged periods of antibiotics, valve replacement surgery, valve repair
Frequency	325,000 children a year
Deaths	319,400 (2015)

Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful joints, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves, known as rheumatic heart disease (RHD), usually occurs after repeated attacks but can sometimes occur after one. The damaged valves may result in heart failure, atrial fibrillation and infection of the valves.

Rheumatic fever may occur following an infection of the throat by the bacterium Streptococcus pyogenes. If the infection is left untreated, rheumatic fever occurs in up to three percent of people. The underlying mechanism is believed to involve the production of antibodies against a person's own tissues. Due to their genetics, some people are more likely to get the disease when exposed to the bacteria than others. Other risk factors include malnutrition and poverty. Diagnosis of RF is often based on the presence of signs and symptoms in combination with evidence of a recent streptococcal infection.

Treating people who have strep throat with antibiotics, such as penicillin, decreases the risk of developing rheumatic fever. In order to avoid antibiotic misuse this often involves testing people with sore throats for the infection; however, testing might not be available in the developing world. Other preventive measures include improved sanitation. In those with rheumatic fever and rheumatic heart disease, prolonged periods of antibiotics are sometimes recommended. Gradual return to normal activities may occur following an attack. Once RHD develops, treatment is more difficult.

Occasionally valve replacement surgery or valve repair is required.

Otherwise complications are treated as per normal.

Rheumatic fever occurs in about 325,000 children each year and about 33.4 million people currently have rheumatic heart disease. Those who develop RF are most often between the ages of 5 and 14, with 20% of first-time attacks occurring in adults. The disease is most common in the developing world and among indigenous peoples in the developed world. In 2015 it resulted in 319,400 deaths down from 374,000 deaths in 1990. Most deaths occur in the developing world where as many as 12.5% of people affected may die each year. Descriptions of the condition are believed to date back to at least the 5th century BCE in the writings of Hippocrates. The disease is so named because its symptoms are similar to those of some rheumatic disorders.

Signs and symptoms

A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in a 16-year-old.

 

The disease typically develops two to four weeks after a throat infection. Symptoms include: fever, painful joints with those joints affected changing with time, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves usually occurs only after multiple attacks but may occasionally occur after a single case of RF. The damaged valves may result in heart failure and also increase the risk of atrial fibrillation and infection of the valves.

Pathophysiology

Rheumatic fever is a systemic disease affecting the connective tissue around arterioles, and can occur after an untreated strep throat infection, specifically due to group A streptococcus (GAS), Streptococcus pyogenes. It is believed to be caused by antibody cross-reactivity. This cross-reactivity is a type II hypersensitivity reaction and is termed molecular mimicry. Usually, self reactive B cells remain anergic in the periphery without T cell co-stimulation. During a streptococcal infection, mature antigen-presenting cells such as B cells present the bacterial antigen to CD4+T cells which differentiate into helper T₂ cells. Helper T₂ cells subsequently activate the B cells to become plasma cells and induce the production of antibodies against the cell wall of Streptococcus. However the antibodies may also react against the myocardium and joints, producing the symptoms of rheumatic fever. S. pyogenes is a species of aerobic, cocci, gram-positive bacteria that are non-motile, non-spore forming, and forms chains and large colonies.

S. pyogenes has a cell wall composed of branched polymers which sometimes contain M protein, a virulence factor that is highly antigenic. The antibodies which the immune system generates against the M protein may cross-react with heart muscle cell protein myosin, heart muscle glycogen and smooth muscle cells of arteries, inducing cytokine release and tissue destruction. However, the only proven cross-reaction is with perivascular connective tissue. This inflammation occurs through direct attachment of complement and Fc receptor-mediated recruitment of neutrophils and macrophages. Characteristic Aschoff bodies, composed of swollen eosinophilic collagen surrounded by lymphocytes and macrophages can be seen on light microscopy. The larger macrophages may become Anitschkow cells or Aschoff giant cells. Rheumatic valvular lesions may also involve a cell-mediated immunity reaction as these lesions predominantly contain T-helper cells and macrophages.

In rheumatic fever, these lesions can be found in any layer of the heart causing different types of carditis. The inflammation may cause a serofibrinous pericardial exudate described as "bread-and-butter" pericarditis, which usually resolves without sequelae. Involvement of the endocardium typically results in fibrinoid necrosis and wart formation along the lines of closure of the left-sided heart valves. Warty projections arise from the deposition, while subendocardial lesions may induce irregular thickenings called MacCallum plaques.

Rheumatic heart disease

Pathophysiology of rheumatic heart disease

 

Micrograph showing an Aschoff body (right of image), as seen in rheumatic heart disease. H&E stain.

 

Chronic rheumatic heart disease (RHD) is characterized by repeated inflammation with fibrinous repair. The cardinal anatomic changes of the valve include leaflet thickening, commissural fusion, and shortening and thickening of the tendinous cords. It is caused by an autoimmune reaction to Group A β-hemolytic streptococci (GAS) that results in valvular damage. Fibrosis and scarring of valve leaflets, commissures and cusps leads to abnormalities that can result in valve stenosis or regurgitation. The inflammation caused by rheumatic fever, usually during childhood, is referred to as rheumatic valvulitis. About half of patients with rheumatic fever develop inflammation involving valvular endothelium. The majority of morbidity and mortality associated with rheumatic fever is caused by its destructive effects on cardiac valve tissue. The pathogenesis of RHD is complex and not fully understood, but it is known to involve molecular mimicry and genetic predisposition that lead to autoimmune reactions.

Molecular mimicry occurs when epitopes are shared between host antigens and Streptococcus antigens. This causes an autoimmune reaction against native tissues in the heart that are incorrectly recognized as "foreign" due to the cross-reactivity of antibodies generated as a result of epitope sharing. The valvular endothelium is a prominent site of lymphocyte-induced damage. CD4+ T cells are the major effectors of heart tissue autoimmune reactions in RHD. Normally, T cell activation is triggered by the presentation of bacterial antigens. In RHD, molecular mimicry results in incorrect T cell activation, and these T lymphocytes can go on to activate B cells, which will begin to produce self-antigen-specific antibodies. This leads to an immune response attack mounted against tissues in the heart that have been misidentified as pathogens. Rheumatic valves display increased expression of VCAM-1, a protein that mediates the adhesion of lymphocytes. Self-antigen-specific antibodies generated via molecular mimicry between human proteins and streptococcal antigens up-regulate VCAM-1 after binding to the valvular endothelium. This leads to the inflammation and valve scarring observed in rheumatic valvulitis, mainly due to CD4+ T cell infiltration.

While the mechanisms of genetic predisposition remain unclear, a few genetic factors have been found to increase susceptibility to autoimmune reactions in RHD. The dominant contributors are a component of MHC class II molecules, found on lymphocytes and antigen-presenting cells, specifically the DR and DQ alleles on human chromosome 6. Certain allele combinations appear to increase RHD autoimmune susceptibility. Human leukocyte antigen (HLA) class II allele DR7 (HLA-DR7) is most often associated with RHD, and its combination with certain DQ alleles is seemingly associated with the development of valvular lesions. The mechanism by which MHC class II molecules increase a host's susceptibility to autoimmune reactions in RHD is unknown, but it is likely related to the role HLA molecules play in presenting antigens to T cell receptors, thus triggering an immune response. Also found on human chromosome 6 is the cytokine TNF-α which is also associated with RHD. High expression levels of TNF-α may exacerbate valvular tissue inflammation, contributing to RHD pathogenesis. Mannose-binding lectin (MBL) is an inflammatory protein involved in pathogen recognition. Different variants of MBL2 gene regions are associated in RHD. RHD-induced mitral valve stenosis has been associated with MBL2 alleles encoding for high production of MBL. Aortic valve regurgitation in RHD patients has been associated with different MBL2 alleles that encode for low production of MBL. Other genes are also being investigated to better understand the complexity of autoimmune reactions that occur in RHD.

Diagnosis

Streptococcus pyogenes bacteria (Pappenheim's stain) the trigger for rheumatic fever.

 

Modified Jones criteria were first published in 1944 by T. Duckett Jones, MD. They have been periodically revised by the American Heart Association in collaboration with other groups. According to revised Jones criteria, the diagnosis of rheumatic fever can be made when two of the major criteria, or one major criterion plus two minor criteria, are present along with evidence of streptococcal infection: elevated or rising antistreptolysin O titre or DNAase. Exceptions are chorea and indolent carditis, each of which by itself can indicate rheumatic fever. An April 2013 review article in the Indian Journal of Medical Research stated that echocardiographic and Doppler (E & D) studies, despite some reservations about their utility, have identified a massive burden of rheumatic heart disease, which suggests the inadequacy of the 1992 Jones' criteria. E & D studies have identified subclinical carditis in patients with rheumatic fever, as well as in follow-ups of rheumatic heart disease patients who initially presented as having isolated cases of Sydenham's chorea. Signs of a preceding streptococcal infection include: recent scarlet fever, raised antistreptolysin O or other streptococcal antibody titre, or positive throat culture.

Major criteria

• Polyarthritis: A temporary migrating inflammation of the large joints, usually starting in the legs and migrating upwards.
• Carditis: Inflammation of the heart muscle (myocarditis) which can manifest as congestive heart failure with shortness of breath, pericarditis with a rub, or a new heart murmur.
• Subcutaneous nodules: Painless, firm collections of collagen fibers over bones or tendons. They commonly appear on the back of the wrist, the outside elbow, and the front of the knees.
• Erythema marginatum: A long-lasting reddish rash that begins on the trunk or arms as macules, which spread outward and clear in the middle to form rings, which continue to spread and coalesce with other rings, ultimately taking on a snake-like appearance. This rash typically spares the face and is made worse with heat.
• Sydenham's chorea (St. Vitus' dance): A characteristic series of involuntary rapid movements of the face and arms. This can occur very late in the disease for at least three months from onset of infection.

Minor criteria

• Fever of 38.2–38.9 °C (100.8–102.0 °F)
• Arthralgia: Joint pain without swelling (Cannot be included if polyarthritis is present as a major symptom)
• Raised erythrocyte sedimentation rate or C reactive protein
• Leukocytosis
• ECG showing features of heart block, such as a prolonged PR interval (Cannot be included if carditis is present as a major symptom)
• Previous episode of rheumatic fever or inactive heart disease

Prevention

Rheumatic fever can be prevented by effectively and promptly treating strep throat with antibiotics.

In those who have previously had rheumatic fever, antibiotics in a preventative manner are occasionally recommended. As of 2017 the evidence to support long term antibiotics in those with underlying disease is poor.

The American Heart Association suggests that dental health be maintained, and that people with a history of bacterial endocarditis, a heart transplant, artificial heart valves, or "some types of congenital heart defects" may wish to consider long-term antibiotic prophylaxis.

Treatment

The management of rheumatic fever is directed toward the reduction of inflammation with anti-inflammatory medications such as aspirin or corticosteroids. Individuals with positive cultures for strep throat should also be treated with antibiotics.

Aspirin is the drug of choice and should be given at high doses.

One should watch for side effects like gastritis and salicylate poisoning. In children and teenagers, the use of aspirin and aspirin-containing products can be associated with Reye's syndrome, a serious and potentially deadly condition. The risks, benefits, and alternative treatments must always be considered when administering aspirin and aspirin-containing products in children and teenagers. Ibuprofen for pain and discomfort and corticosteroids for moderate to severe inflammatory reactions manifested by rheumatic fever should be considered in children and teenagers.

Vaccine

No vaccines are currently available to protect against S. pyogenes infection, although research is underway to develop one. Difficulties in developing a vaccine include the wide variety of strains of S. pyogenes present in the environment and the large amount of time and people that will be needed for appropriate trials for safety and efficacy of the vaccine.

Infection

People with positive cultures for Streptococcus pyogenes should be treated with penicillin as long as allergy is not present. The use of antibiotics will not alter cardiac involvement in the development of rheumatic fever. Some suggest the use of benzathine benzylpenicillin. 

Monthly injections of long-acting penicillin must be given for a period of five years in patients having one attack of rheumatic fever. If there is evidence of carditis, the length of therapy may be up to 40 years. Another important cornerstone in treating rheumatic fever includes the continual use of low-dose antibiotics (such as penicillin, sulfadiazine, or erythromycin) to prevent recurrence.

Inflammation

While corticosteroids are often used, evidence to support this is poor. Salicylates are useful for pain.

Steroids are reserved for cases where there is evidence of an involvement of the heart. The use of steroids may prevent further scarring of tissue and may prevent the development of sequelae such as mitral stenosis.

Heart failure

Some patients develop significant carditis which manifests as congestive heart failure. This requires the usual treatment for heart failure: ACE inhibitors, diuretics, beta blockers, and digoxin. Unlike typical heart failure, rheumatic heart failure responds well to corticosteroids.

Epidemiology

Deaths from rheumatic heart disease per million persons in 2012

  0–7

  8–14

  15–20

  21–25

  26–32

  33–38

  39–45

  46–52

  53–63

  64–250

Disability-adjusted life year for rheumatic heart disease per 100,000 inhabitants in 2004.

  no data

  less than 20

  20–40

  40–60

  60–80

  80–100

  100–120

  120–140

  140–160

  160–180

  180–200

  200–330

  more than 330

About 33 million people are affected by rheumatic heart disease with an additional 47 million having asymptomatic damage to their heart valves. As of 2010 globally it resulted in 345,000 deaths, down from 463,000 in 1990.

In Western countries, rheumatic fever has become fairly rare since the 1960s, probably due to the widespread use of antibiotics to treat streptococcus infections. While it has been far less common in the United States since the beginning of the 20th century, there have been a few outbreaks since the 1980s. The disease is most common among Indigenous Australians (particularly in central and northern Australia), Māori, and Pacific Islanders, and is also common in Sub-Saharan Africa, Latin America, the Indian Subcontinent, the Middle East, and North Africa.

Rheumatic fever primarily affects children between ages 5 and 17 years and occurs approximately 20 days after strep throat. In up to a third of cases, the underlying strep infection may not have caused any symptoms. 

The rate of development of rheumatic fever in individuals with untreated strep infection is estimated to be 3%. The incidence of recurrence with a subsequent untreated infection is substantially greater (about 50%). The rate of development is far lower in individuals who have received antibiotic treatment. Persons who have suffered a case of rheumatic fever have a tendency to develop flare-ups with repeated strep infections. 

The recurrence of rheumatic fever is relatively common in the absence of maintenance of low dose antibiotics, especially during the first three to five years after the first episode. Recurrent bouts of rheumatic fever can lead to valvular heart disease. Heart complications may be long-term and severe, particularly if valves are involved. In countries in Southeast-Asia, sub-saharan Africa, and Oceania, the percentage of people with rheumatic heart disease detected by listening to the heart was 2.9 per 1000 children and by echocardiography it was 12.9 per 1000 children.