Overview
This lecture covers rheumatic fever and rheumatic heart disease, focusing on their pathogenesis, diagnostic criteria, pathological features, and common university exam questions.
Structure of the Heart
- The heart has four chambers: two atria (oracles) and two ventricles.
- The heart contains three layers: endocardium (inner), myocardium (middle), and pericardium (outer).
- Heart valves are made solely of endocardium.
Rheumatic Fever vs. Rheumatic Heart Disease
- Rheumatic fever is a multisystem autoimmune disease following group A streptococcal (GAS) pharyngitis.
- Rheumatic heart disease is one of five possible manifestations of rheumatic fever.
Pathogenesis of Rheumatic Fever
- Occurs in children, typically 3-5 years old, after GAS pharyngitis.
- Molecular mimicry: antibodies against GAS M protein cross-react with human tissues.
- Main affected organs: heart, brain, skin, subcutaneous tissue, and joints.
Clinical Manifestations (Jones Criteria)
Major Criteria
- Carditis (pancarditis/rheumatic heart disease)
- Chorea (Sydenham’s chorea)
- Erythema marginatum (skin)
- Subcutaneous nodules
- Migratory polyarthritis (joints)
Minor Criteria
- Fever
- Arthralgia (joint pain, not swelling)
- Elevated ESR/CRP/WBC count
- Prolonged PR interval on ECG
GAS (Supporting) Criteria
- Positive throat culture or rapid antigen test
- Elevated or rising streptococcal antibody titers (ASO or anti-DNase B)
Diagnostic Rules
- Diagnosis: Either 2 major criteria, or 1 major plus 2 minor, with evidence of preceding GAS infection.
Pathology of Rheumatic Heart Disease
- Pancarditis involves all three heart layers: endocardium (vegetations, MacCallum patch), myocardium (Aschoff bodies/granulomas), pericardium (fibrinous pericarditis).
- Vegetations: Small, sterile nodules along the line of valve closure, most commonly mitral> aortic > tricuspid > pulmonary.
- Deformity: Fish mouth/buttonhole appearance due to valve scarring.
- Aschoff bodies: Granulomatous lesions with central fibrinoid necrosis, surrounded by Aschoff and Anitschkow cells (modified macrophages).
Key Terms & Definitions
- Rheumatic Fever — Autoimmune disease occurring after streptococcal infection, affecting multiple organs.
- Rheumatic Heart Disease — Cardiac manifestation (pancarditis) of rheumatic fever.
- Molecular Mimicry — Immune response to bacterial antigens cross-reacting with host tissues.
- Jones Criteria — Clinical guidelines for diagnosing rheumatic fever, split into major and minor criteria.
- Vegetations — Small, sterile nodules on heart valves.
- Aschoff Body — Myocardial granuloma with central fibrinoid necrosis.
- MacCallum Patch — Thickened, wrinkled area of endocardium, typically in the left atrium.
- Bread and Butter Pericarditis — Fibrinous exudate between pericardial layers resembling bread and butter.
Action Items / Next Steps
- Review the lecture notes and diagrams, focusing on Jones criteria and cardiac pathology.
- Solve previous university exam questions related to rheumatic fever and rheumatic heart disease.
- Prepare for possible short and long exam questions on diagnosis, pathogenesis, and pathology.