Rheumatic Heart Disease

RHD Pathogenesis - Strep's Delayed Attack

• Trigger: Group A β-hemolytic Streptococcus (GAS) pharyngitis (untreated/inadequately treated).
• Mechanism: Molecular mimicry.
  • Bacterial M protein & carbohydrates (e.g., N-acetylglucosamine) share antigenic similarity with host tissues.
  • Host antibodies produced against GAS (e.g., anti-streptolysin O, anti-DNase B) cross-react with cardiac myosin, valvular endothelium, synovium, and brain antigens.
• Timeline: Delayed, non-suppurative autoimmune sequela, typically 2-4 weeks after acute GAS infection.
• Key Pathology:
  • Pancarditis: Inflammation affecting endocardium, myocardium, and pericardium.
  • Aschoff bodies: Pathognomonic granulomatous lesions in myocardium; collections of lymphocytes, plasma cells, and characteristic Anitschkow cells (macrophages with caterpillar-like nuclei).

⭐ Aschoff bodies are pathognomonic for rheumatic carditis.

• Genetic predisposition influences susceptibility (certain HLA types, e.g., HLA-DR4, DR2).

Jones Criteria - Diagnostic Checklist

Diagnosis (mod/high-risk populations): 2 Major OR 1 Major + 2 Minor criteria, PLUS evidence of recent Group A Strep (GAS) infection.

• Major Criteria (📌 JONES):
  • Joints: Polyarthritis (migratory)
  • O (♥): Carditis (clinical/subclinical)
  • Nodules: Subcutaneous (painless)
  • Erythema Marginatum
  • Sydenham's Chorea
• Minor Criteria (mod/high-risk):
  • Monoarthralgia
  • Fever (≥ 38°C)
  • ↑ESR (≥30 mm/hr) OR ↑CRP (≥3.0 mg/dL)
  • Prolonged PR interval (ECG)
• Essential: Evidence of Preceding GAS Infection:
  • ↑ASO or Anti-DNase B titers
  • Positive GAS throat culture or Rapid Antigen Detection Test (RADT)
  • Recent scarlet fever (if documented)

⭐ Carditis is the most serious manifestation of acute rheumatic fever and the only one causing permanent damage.

Investigations & Valvular Lesions - Heart's Echoes

• Key Investigations:
  • ↑ ASO titre, ↑ ESR/CRP (inflammation markers).
  • ECG: PR prolongation, chamber enlargement signs.
  • Chest X-ray: Cardiomegaly, pulmonary congestion.
  • Echocardiography (2D Echo & Doppler): Gold standard. Confirms diagnosis, assesses valve damage & function.
• Common Valvular Lesions (Echo findings):
  • Acute Phase:
    • Mitral Regurgitation (MR): Most common (📌 Carey Coombs murmur).
    • Aortic Regurgitation (AR).
    • Valvulitis: Annular dilatation, leaflet edema, prolapse, chordal elongation.
  • Chronic Phase:
    • Mitral Stenosis (MS): Most frequent. "Fish-mouth" valve.
    • MR, AR, Aortic Stenosis (AS).
    • Thickened, fibrosed, calcified leaflets; chordal fusion.

⭐ Mitral valve is the most commonly affected valve in chronic RHD, typically leading to mitral stenosis.

Management & Prophylaxis - Shielding the Heart

Acute Rheumatic Fever (ARF) Management:

• Goals: Control inflammation, eradicate GAS, manage complications.
• Bed rest; Aspirin (arthritis/fever); Prednisolone (carditis).
• Eradicate GAS: Benzathine Penicillin G 1.2 MU IM (single dose, 0.6 MU if <27kg) or oral Penicillin V (10 days).

Secondary Prophylaxis (Prevent Recurrence & RHD Progression):

⭐ Secondary prophylaxis with Benzathine Penicillin G is the cornerstone of preventing RHD progression and recurrence.

• Primary: Benzathine Penicillin G 1.2 MU IM every 3-4 weeks (📌 Benzathine Prevents Going back).
  • Every 3 weeks for high-risk/severe carditis.
• Alternatives (penicillin allergy): Sulfadiazine, Erythromycin.
• Duration guided by RHD severity (see flowchart).

High‑Yield Points - ⚡ Biggest Takeaways

• Most common cause of acquired heart disease in children worldwide.
• Follows Group A Streptococcal (GAS) pharyngitis; an autoimmune reaction.
• Revised Jones Criteria (major/minor) for diagnosis, needs prior GAS infection evidence.
• Pancarditis is common; mitral valve most affected (initially MR, later MS).
• Aschoff bodies (myocardial granulomas) are pathognomonic.
• Sydenham's chorea is a late, specific major neurological sign.
• Long-term penicillin prophylaxis prevents recurrence and valvular damage.