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Acute Rheumatic Fever

Acute rheumatic fever

Pathogenesis and Clinical Findings

Overview

• Pathogenesis:
  • Untreated GAS Pharyngitis
  • Environmental Factors
  • Genetic Susceptibility

Pathogenesis

1. Initial Event:
   • Untreated Group A Streptococcus (GAS) pharyngitis
2. Delayed Autoimmune Reaction:
   • Triggered by molecular mimicry where GAS antigen cross-reacts with host tissues
3. Activation of Immune Response:
   • Activation of auto-reactive B and CD-4+ T cells
4. Tissue Injury and Inflammation:
   • Outcomes:
     • Clinical Findings:
       • Fever
       • Arthralgia
       • Erythema Marginatum
       • Subcutaneous Nodules (Osler’s Nodes)
       • Increased ESR and CRP
     • Mechanisms:
       • Antibodies recognize ganglioside and N-acetyl-β-D-glucosamine, targeting neuronal cell surfaces, leading to Sydenham’s Chorea via cell signaling and dopamine release.
       • Antibodies attach to myosin and other cardiac proteins. Lymphocytes adhere to these proteins causing pancarditis and valvular injury, resulting in carditis and prolonged PR interval.

Genetic and Environmental Factors

• Genetic Susceptibility:
  • Polygenic, involving HLA-DR7 and other class II MHC alleles.
  • Single nucleotide polymorphisms (SNPs) for TNF-alpha and Mannan-binding lectin.
• Environmental Risk Factors:
  • Overcrowding
  • Poverty
  • Malnutrition
  • Maternal unemployment
  • Low level of maternal education

Prevention

• Treatment of GAS pharyngitis with a full course of antibiotics can reduce the risk of developing rheumatic fever.

Long-term Sequelae

• Rheumatic heart disease, commonly valvulopathy.
• Jaccoud arthropathy: a benign chronic arthropathy causing joint and tendon loosening in hands/feet.

Introduction and Epidemiology

View or edit this diagram in Whimsical.

Diagnosis

• Definition of Low-Risk Population:
  • Cases of acute RF ≤ 2/100,000 school-age children or rheumatic heart disease.

View or edit this diagram in Whimsical.

Echocardiographic Criteria (AHA 2012)

Doppler Criteria

• Pathological Mitral Regurgitation (all must be met):

  1. Visible in at least 2 projections.
  2. Regurgitation jet length ≥ 2 cm in at least 1 projection.
  3. Regurgitation peak velocity > 3 m/s.
  4. Regurgitation pansystolic.

• Pathological Aortic Regurgitation (all must be met):

  1. Visible in at least 2 projections.
  2. Regurgitation jet length ≥ 1 cm in at least 1 projection.
  3. Regurgitation peak velocity > 3 m/s.
  4. Regurgitation pandiastolic.

Morphological Criteria

• Acute Mitral Valve Involvement:

  1. Dilatation of mitral annulus.
  2. Elongation of chordae tendineae.
  3. Rupture of chorda tendinea with acute mitral regurgitation.
  4. Prolapse of anterior (less often posterior) leaflet.
  5. Nodular lesions on leaflets.

• Chronic Mitral Valve Involvement:

  1. Thickening of leaflets.
  2. Thickening and fusion of chordae tendineae.
  3. Limited leaflet mobility.
  4. Calcifications.

• Acute and Chronic Aortic Valve Involvement:

  1. Symmetrical or focal thickening of leaflets.
  2. Disturbed leaflet coaptation.
  3. Limited leaflet mobility.
  4. Prolapse of leaflets.

Treatment

Primary Prevention

• Indication: Treatment of group A streptococcal (GAS) pharyngitis to prevent the first episode of acute rheumatic fever (ARF).
• Preferred Agent:
  • Phenoxymethylpenicillin (Penicillin V)
    • Dose: 500 mg orally twice daily for 10 days (250 mg for children <27 kg).
• Penicillin Allergy (non-anaphylactic)
  • First-generation cephalosporins (e.g., cephalexin).
• Penicillin Allergy (anaphylactic):
  • Macrolides (e.g., azithromycin or erythromycin).

Secondary Prevention

• Goal: Prevent recurrence of ARF and progression to chronic RHD.
• Preferred Agents:
  • Benzathine benzylpenicillin IM every 3–4 weeks (first-line).
  • Phenoxymethylpenicillin orally twice daily.
  • Macrolides if allergic to penicillin.
• Dosage:
  • Phenoxymethylpenicillin: 250 mg orally twice daily.

Duration of Secondary Prophylaxis

• Without carditis:

  • Until 21 years of age or 5 years after last ARF episode, whichever is longer.

• With carditis but no residual valvular disease:

  • Until 25 years of age or 10 years after last ARF, whichever is longer.

• With carditis and persistent valvular heart disease:

  • Until 40 years of age or 10 years after last ARF, whichever is longer; some guidelines recommend lifelong prophylaxis.

Anti-inflammatory Treatment

• Prednisone:
  • Dosage: 1–2 mg/kg/day for 2–3 weeks, then taper gradually.
  • Total duration: 6 weeks.

Links

• Infective endocarditis
• Valvular heart disease
• Cardiac physiology
• Cardiac disease in pregnancy
• Anaesthetic management of specific cardiac conditions

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References:

1. Szczygielska, I., Hernik, E., Kołodziejczyk, B., Gazda, A., Maślińska, M., & Gietka, P. (2018). Rheumatic fever–new diagnostic criteria. Rheumatology, 56(1), 37-41. https://doi.org/10.5114/reum.2018.74748
2. The Calgary Guide to Understanding Disease. (2024). Retrieved June 5, 2024, from https://calgaryguide.ucalgary.ca/
3. FRCA Mind Maps. (2024). Retrieved June 5, 2024, from https://www.frcamindmaps.org/
4. Anesthesia Considerations. (2024). Retrieved June 5, 2024, from https://www.anesthesiaconsiderations.com/

Summaries:

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© 2025 Francois Uys. All Rights Reserved.

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