Understanding Rheumatic Fever: Causes, Symptoms, and Complications

Rheumatic Fever

Is a multisystem inflammatory disease that can involve the heart, joints, skin, and brain. The disease develops after a streptococcal infection (A beta-hemolytic – Streptococcus pyogenes) – mostly pharyngitis

Clinical Features

• Occur most often in children
• Develop 2-4 weeks after streptococcal infection
• Fever, malaise, and increased erythrocyte sedimentation rate
• Rheumatic heart disease – pancarditis; inflammation of the entire heart (3 layers)

Pericarditis

Leads to serous effusions

Myocarditis

Leads to cardiac failure

Endocarditis

Leads to valvular damage

• Rheumatic endocarditis – mitral and aortic valves (mostly); the valves become thickened, fibrotic, deformed, & calcification (may)

• Joint involvement – arthralgia, arthritis, and migratory polyarthritis
• Skin lesions – subcutaneous nodules and erythema marginatum (distinctive)
• CNS involvement – Sydenham chorea (involuntary muscular movements)
• If chronic – arrhythmias and thromboembolic complications

Causes

• Immunologic origin rather than a result of direct bacterial involvement
• Streptococcal antigens – molecular mimicry – elicit an antibody cross-reactivity

Mechanism

• Type II hypersensitivity – attributed to antibodies against group A streptococcal molecules that cross-react with host myocardial antigens

Morphology

Acute Rheumatic Fever

• Inflammation foci within several tissues
• Aschoff bodies – focal interstitial myocardial inflammation, with:

• Aschoff cells – multinucleated giant cells
• Anitschkow myocytes or “caterpillar cells”
• Collagen and fibrinoid material

• Aschoff bodies can be found in all three layers of the heart
• The pericardium exhibits fibrinous exudate
• The endocardium may contain verrucae (1-2mm vegetations)

Chronic Rheumatic Fever

• Organization of acute diffuse inflammation and scarring
• Aschoff bodies are replaced by fibrous scar – therefore not seen in chronic RF
• Cardiac valves show leaflet thickening, commissural fusion and shortening, and thickening of the chordae tendinea
• Calcification creates buttonhole stenoses
• Neovascularization

Rheumatic Heart Disease

• Valvular stenosis and regurgitation

• 70% mitral valve
• 25% mitral and aortic valves
• 5% tricuspid valve

• Mitral valve stenosis à left atrium dilation à atrial fibrillation à mural thrombosis