Cause
- 1.
Acute rheumatic fever is believed to be an immunologic response that occurs as a delayed sequela of group A streptococcal infection of the pharynx but not of the skin. The attack rate of acute rheumatic fever after streptococcal infection varies with the severity of the infection, ranging from 0.3% to 3%.
- 2.
Important predisposing factors include family history of rheumatic fever, low socioeconomic status (poverty, poor hygiene, medical deprivation), and age between 6 and 15 years (with a peak incidence at 8 years of age).
Pathology
- 1.
The inflammatory lesion is found in many parts of the body, most notably in the heart, brain, joints, and skin.
- 2.
Rheumatic carditis was considered to be pancarditis, with myocarditis being the most important element. It is now recognized that the valvular component may be as important as or much more important than myocardial and pericardial involvement. In rheumatic myocarditis, myocardial contractility is rarely impaired, and the serum level of troponin is not elevated. It is not only the valve leaflets that are heavily involved with fibrinous vegetations on the coapting surfaces, but the entire mitral valve apparatus is also involved (with annular dilatation and stretching of chordae tendineae).
- 3.
Valvular damage most frequently and most severely involves the mitral, less commonly the aortic, and rarely the tricuspid and pulmonary valves.
- 4.
Aschoff bodies in the atrial myocardium are believed to be characteristic of rheumatic fever. These consist of inflammatory lesions associated with swelling, fragmentation of collagen fibers, and alterations in the staining characteristics of connective tissue, now believed to be necrotic myocardial cells.
Clinical Manifestations
Acute rheumatic fever is diagnosed by the use of revised Jones criteria (updated in 1993; see Box 20-1 ). The criteria are three groups of important clinical and laboratory findings: (1) five major manifestations, (2) four minor manifestations, and (3) supporting evidence of an antecedent group A streptococcal infection. These and other important clinical findings are presented here.
| MAJOR MANIFESTATIONS | MINOR MANIFESTATIONS |
|---|---|
|
|
Supporting Evidence of Antecedent Group A Streptococcal Infection
Positive throat culture or rapid streptococcal antigen test result
Elevated or rising streptococcal antibody titer
CRP, C-reactive protein; ESR, erythrocyte sedimentation rate.
• If supported by evidence of preceding group A streptococcal infection, the presence of two major manifestations or of one major and two minor manifestations indicates a high probability of acute rheumatic fever.
History
- 1.
History of streptococcal pharyngitis, 1 to 5 weeks (average, 3 weeks) before the onset of symptoms, is common. The latent period may be as long as 2 to 6 months (average, 4 months) in cases of isolated chorea.
- 2.
Pallor, malaise; easy fatigability; and other history, such as epistaxis (5%–10%) and abdominal pain, may be present.
Major Manifestations
Five major criteria of acute rheumatic fever are discussed below.
Arthritis
Arthritis, the most common manifestation of acute rheumatic fever (70% of cases), usually involves large joints (e.g., knees, ankles, elbows, wrists). Often more than one joint is involved, either simultaneously or in succession, with a characteristic migratory nature of the arthritis. Swelling, heat, redness, severe pain, tenderness, and limitation of motion are common. If the patient was given salicylate-containing analgesics, these signs of inflammation may be mild. The arthritis responds dramatically to salicylate therapy; if patients treated with salicylates (with documented therapeutic levels) do not improve in 48 hours, the diagnosis of acute rheumatic fever probably is incorrect.
Carditis
Carditis occurs in 50% of patients. Signs of carditis include some or all of the following.
- 1.
Tachycardia (out of proportion to the degree of fever) is common; its absence makes the diagnosis of myocarditis unlikely.
- 2.
A heart murmur of mitral regurgitation (MR) or aortic regurgitation (AR) (or both) is almost always present. Although the American Heart Association’s Jones criteria recommend not to make the diagnosis of acute rheumatic carditis without audible murmurs of MR or AR, this is debatable. Significant echocardiographic abnormalities may be present in the absence of heart murmur.
Echocardiographic examination can determine the severity of cardiac enlargement, the presence and degree of MR and AR, and the presence of pericardial effusion more objectively than auscultation can. Inclusion of echocardiographic abnormalities may enhance the correct diagnosis of acute rheumatic carditis ( Vijayalakshmi et al, 2005 ). However, a hemodynamically insignificant echocardiographic finding of MR alone is considered insufficient to diagnose myocarditis. Gross prolapse of the mitral valve or the presence of posterolateral (not central) MR jet by color-flow mapping may be significant. (With chronic rheumatic MR, fusion of the leaflets and cordae and contracture of these structures occur, and the regurgitation jets tends to become more central.) Other abnormal echocardiographic findings may include pericardial effusion, increased left ventricular (LV) dimension, or impaired LV function.
- 3.
Pericarditis (with friction rub, pericardial effusion, chest pain, and electrocardiographic [ECG] changes) may be present. Pericarditis does not occur without mitral valve involvement in rheumatic fever. Pericardial effusion is usually of small amount and almost never causes cardiac tamponade.
- 4.
Cardiomegaly on chest radiograph is indicative of severity of rheumatic carditis (or valvulitis) or congestive heart failure (CHF).
- 5.
Signs of CHF (gallop rhythm, distant heart sounds, cardiomegaly) are indications of severe cardiac dysfunction.
Erythema Marginatum
Erythema marginatum occurs in fewer than 10% of patients with acute rheumatic fever. The characteristic nonpruritic serpiginous or annular erythematous rashes are most prominent on the trunk and the inner proximal portions of the extremities; they are never seen on the face. The rashes are evanescent, disappearing on exposure to cold and reappearing after a hot shower or when the patient is covered with a warm blanket. They seldom are detected in air-conditioned rooms.
Subcutaneous Nodules
Subcutaneous nodules are found in 2% to 10% of patients, particularly in cases with recurrences; it is almost never present as a sole manifestation of rheumatic fever. They are hard, painless, nonpruritic, freely movable, swelling, and 0.2 to 2 cm in diameter. They usually are found symmetrically, singly or in clusters, on the extensor surfaces of both large and small joints, over the scalp, or along the spine. They are not transient, lasting for weeks, and have a significant association with carditis. Subcutaneous nodules are not exclusive to rheumatic fever. They occur in 10% of children with rheumatoid arthritis, and benign subcutaneous nodules have been described in children and adults. In adults, they occur with rheumatoid arthritis, systemic lupus erythematosus (SLE), and other diseases.
Sydenham’s Chorea
Sydenham’s chorea (St. Vitus’ dance) is found in 15% of patients with acute rheumatic fever. It occurs more often in prepubertal girls (8–12 years) than in boys. It is a neuropsychiatric disorder consisting of both neurologic signs (choreic movement and hypotonia) and psychiatric signs (e.g., emotional lability, hyperactivity, separation anxiety, obsessions, and compulsions). It begins with emotional lability and personality changes. These are soon replaced (in 1–4 weeks) by the characteristic spontaneous, purposeless movement of chorea (which lasts 4–18 months), followed by motor weakness. The distractability and inattentiveness outlast the choreic movements. The adventitious movements, weakness, and hypotonia continue for an average of 7 months (up to 17 months) before slowly waning in severity. Recently, elevated titers of “antineuronal antibodies” recognizing basal ganglion tissues have been found in more than 90% of patients. The levels of the antineuronal antibody titer are positively related to the severity of choreic movements. These findings suggest that chorea may be related to dysfunction of basal ganglia and cortical neuronal components.
Minor Manifestations
The following are four minor criteria for the diagnosis of acute rheumatic fever.
- 1.
Arthralgia refers to joint pain without the objective changes of arthritis. It must not be considered a minor manifestation when arthritis is used as a major manifestation in making the diagnosis of rheumatic fever.
- 2.
Fever (usually with a temperature of at least 102°F [38.8 ° C]) is present early in the course of untreated rheumatic fever.
- 3.
In laboratory findings, elevated acute-phase reactants (elevated C-reactive protein [CRP] levels and elevated erythrocyte sedimentation rate [ESR]) are objective evidence of an inflammatory process.
- 4.
A prolonged PR interval on the ECG is neither specific for acute rheumatic fever nor an indication of active carditis.
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