Rheumatic Fever and Rheumatic Heart Disease

Definition:

Rheumatic fever (RF) is an acute, immunologically mediated, multisystem inflammatory disease involving heart, joints, CNS, skin and other tissues that occurs a few weeks after an episode of group A β-hemolytic streptococcal pharyngitis. Acute rheumatic heart disease (RHD) is the cardiac manifestation of RF and is associated with inflammation of the valves, myocardium, or pericardium. Rheumatic fever is said to “lick the knee but bite the heart”.

Pathogenesis:

Phase 1:

1. β-hemolytic streptococci (Group A) pharygitis
2. Formation of antistreptococcal antibodies which cross reacts with endogenous tissue antigens in heart (Antibody against Streptococcal M protein cross reacts with Cardiac myosin and Sarcolemma), joints (Antibody against Streptococcal hyaluronic acid cross reacts with connective tissue proteoglycans) and other tissues

Phase 2 (2 weeks Post-infection):

1. Joints: Acute febrile polyarthritis
2. Heart: Pancarditis
3. Eye: Uveitis
4. Kidney: Acute glomerulonephritis
5. Brain: Sydenham chorea (rare)

Morphology:

A. Acute Rheumaic Heart Disease:

1. Aschoff bodies or Rheumatic granuloma: Fibrinoid necrosis demarcated by:

• Antischkow cells (Specialized histiocytes resembling Epithelioid cells which appears catterpillar like in cross section and owl’s eye in longitudinal section)
• Lymphoplasmacytic infiltrate (Sparse)
• Rarely Aschoff cells (Inflammatory Giant cells)

2. Pancarditis: Diffuse inflammation and Aschoff Bodies in any of the 3 layers of heart – pericardium, myocardium, endocardium (including valves)

• Pericardium: “Bread and Butter” Pericarditis (Fibrinous or Serofibrinous)
• Myocardium: Myocarditis (Scattered Aschoff bodies within interstitial connective tissue)
• Endocardium: Fibrinoid necrosis along the lines of closure of valves forming 1 to 2 mm vegetations (verrucae); Macculum plaques usually in left atrium

B. Chronic Rheumatic Heart Disease:

1. Organization of Acute Inflammation and Subsequent Fibrosis:

• Valve leaflet thickening
• Commisural fusion and shortening
• Thickening and fusion of chordae tendinae
• “Fish mouth” or “Button hole” Stenoses: Fibrous bridging across the valvular commisures and calcification

2. Microscopical Examination:

• Diffuse fibrosis and neovascularization
• Aschoff bodies replaced by fibrous scar

Functional Consequences:

1. Valvular stenosis and regurgitation
2. Stenosis > Regurgitation
3. Involvement of Mitral valve alone: 70%
4. Involvement of both Mitral and Aortic valve: 25%
5. Mitral stenosis: 99% (Left atrium dilate and may harbor mural thrombi)
6. Long-standing congestive pulmonary changes: Leads to Right ventricular hypertrophy

Jone’s Criteria:

A. Major: “SPACE”

1. Subcutaneous nodules
2. Pancraditis
3. Migratory polyArthritis
4. Sydenham Chorea
5. Erythema Marginatum of Skin

B. Minor: LEAF

1. Fever
2. Arthralgia
3. Leukocytosis and Raised ESR (Erythrocyte Sedimentation Rate)

Diagnosis: Either of the following

1. Essential criteria (serologic evidence of a previous streptococcal infection) + 2 or more Major Criteria
2. 1 Major Criteria + 2 Minor Criteria

Notes:

• The clinical course of rheumatic fever involves a childhood infection with complications in adulthood (cardiac defect).
• Myocardial scarring following ischemia occurs far from vascular structures but in rheumatic fever scarring occurs close to vascular structures.
• Rheumatic fever in children proceeds from the myocardium to the endocardium to the joints; in adults, it proceeds from the joints to the endocardium to the myocardium.