Etiology and mechanisms of development
It is well established that the triggering factor of the disease is group A $\beta$-hemolytic streptococcus. This is evidenced by the clear connection between attacks and preceding nasopharyngeal infections (e.g., tonsillitis), an increase in specific antibodies in the blood, and the effectiveness of antibacterial therapy in preventing relapses.
The basis of pathogenesis is the «molecular mimicry» phenomenon. Streptococcal antigens share structural similarities with normal human tissues, primarily the myocardial sarcolemma. As a result, the antibodies produced by the immune system to destroy the bacteria begin to attack the heart's own cells. Family and genetic predisposition also plays an important role: polygenic inheritance determines the individual nature of the immune response and the variety of clinical manifestations in different patients.
Clinical debut and extracardiac manifestations
The disease most often starts in childhood or adolescence (under 15 years of age). The classic debut unfolds 2–3 weeks after an episode of tonsillitis and manifests as a triad: polyarthritis, signs of carditis, and fever.
Extracardiac manifestations include several syndromes:
- Joint syndrome: acute «migratory» polyarthritis with a fever up to 38 °C. Large joints are predominantly affected, presenting with swelling and tenderness. Note: in modern practice, full-blown arthritis is less common, while polyarthralgias (joint pain without visible inflammation) are observed more frequently.
- Skin syndromes: annular erythema (annular erythema). Erythema nodosum (erythema nodosum) and subcutaneous rheumatic nodules along the tendons are significantly less common.
- Involvement of serous membranes: serositis may develop, such as pleurisy.
- Nervous system involvement (neurorheumatism): typical for children, manifesting as Sydenham's chorea. Patients exhibit hyperkinesia (involuntary, purposeless movements), muscle weakness (hypotonia), and pronounced emotional lability.
Heart involvement (Rheumatic carditis)
Rheumatic carditis is the leading manifestation of the disease, determining its prognosis. Inflammation can affect various layers of the heart:
- Myocarditis: usually focal in nature and mild. Patients complain of palpitations, extrasystoles, chest discomfort, and mild dyspnea upon exertion. Auscultation reveals muffling of the first heart sound and a soft systolic murmur at the apex. Heart dimensions usually remain within normal limits.
- Valvulitis and pericarditis: the development of valvulitis can be suspected by the appearance of a diastolic murmur at the cardiac apex. When the pericardium is involved, a pericardial friction rub is auscultated.
- Outcomes: the main reliable criterion of past rheumatic fever is the development of a heart valve defect, most commonly mitral stenosis (often combined with insufficiency). Isolated mitral insufficiency develops rarely. In a significant proportion of patients (more than one-third), the acute phase is latent, and the diagnosis is established retrospectively already at the stage of established valvular disease.
Recurrent rheumatic carditis
Repeated attacks occur with relapses of streptococcal infection. The diagnosis of recurrent carditis is very difficult because its symptoms are «masked» by pre-existing heart valve disease.
The key sign of exacerbation is the progression of heart failure, which stops responding to standard therapy, as well as the formation of new valvular defects. Clinically, the attack is accompanied by fever, arthralgia or arthritis, and cardialgia. Laboratory tests register inflammatory activity.
Laboratory and instrumental diagnostics
A complex of methods is used to confirm the diagnosis and assess the activity of the process.
Electrocardiography (ECG):
- Conduction disorders: prolongation of the P-Q interval (first-degree AV block), which may be transient, as well as intraventricular blocks.
- Rhythm and repolarization changes: T wave flattening, ST segment displacement, extrasystoles.
Important: sometimes transient ECG changes are the only objective evidence of active carditis.
Laboratory markers:
- Nonspecific (inflammation markers): leukocytosis with a left shift, accelerated ESR, appearance of C-reactive protein (CRP), increase in $\alpha_2$- and $\gamma$-globulins, changes in flocculation tests (sublimate, thymol tests).
- Specific (immunological): elevated titers of antibodies to streptococcus (antistreptolysin-O, antistreptokinase, antistreptohyaluronidase). These markers confirm the association of the exacerbation with a recent GAS infection.
Briefly: answers to topical questions
What clinical and diagnostic Jones criteria are used to diagnose rheumatic fever?
To establish a diagnosis, the Jones diagnostic criteria are used, divided into «major» and «minor». A diagnosis of a first attack is justified in the presence of two major criteria or one major and two minor criteria, plus mandatory confirmation of a recent group A beta-hemolytic streptococcus infection.
Major criteria:
- Carditis
- Polyarthritis
- Chorea
- Erythema marginatum (erythema annulare/marginatum)
- Subcutaneous rheumatic nodules
Minor criteria:
- Clinical: arthralgia, fever.
- Laboratory: elevated ESR and C-reactive protein.
- Instrumental: P-R interval prolongation on ECG.
What antibacterial therapy is used for streptococcal eradication in rheumatic fever?
The cited sources do not specify a particular antibacterial eradication regimen for streptococcus in rheumatic fever. The use of antibiotics for secondary prevention—preventing new attacks/exacerbations of rheumatic fever—is confirmed. Penicillin-class drugs are used for this prevention; natural penicillins are indicated as drugs of choice for benzathine penicillin prophylaxis of rheumatic diseases. For rheumatic tricuspid valve disease, the source indicates the duration of prophylaxis: 10 years after the last exacerbation or until the age of 40; lifelong prophylaxis is indicated for high-risk patients with tricuspid stenosis who are GAS carriers.
The classic triad of a rheumatic attack onset: «Joints, Heart, Heat» (polyarthritis, signs of carditis, elevated temperature).
Class and exam questions
Which heart valve defect is most characteristic of rheumatic fever?
A reliable criterion for the rheumatic nature of the disease is considered to be the development of mitral stenosis. It often occurs in combination with mitral valve insufficiency, whereas isolated insufficiency is rare.
How does joint syndrome manifest in rheumatic fever?
The classic variant is acute «migratory» polyarthritis of large joints, accompanied by fever, swelling, and tenderness. However, today polyarthralgias without objective signs of inflammation are more common.
What is neurorheumatism and who gets it?
Neurorheumatism is typical for childhood. It manifests as Sydenham's chorea—a condition in which a child experiences involuntary, purposeless movements (hyperkinesia), muscle weakness, and marked psychoemotional lability.
What else to study on this topic
- Mechanisms of mitral stenosis development in rheumatic valvulitis
- Features of the latent course of acute rheumatic fever
- Interpretation of transient AV blocks on ECG in carditis
- Differential diagnosis of recurrent rheumatic carditis and progressive heart failure
- Significance of specific immunological markers (ASO) in retrospective diagnostics
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