300.3 🏥 內科專科考前版

300.3.1 Mechanistic Deep Dive

300.3.1.1 Molecular Mimicry

  • M protein on Strep cross-reacts with myosin (heart), tropomyosin, neural antigens
  • Triggers Type II hypersensitivity
  • Genetic susceptibility (HLA-DR7, HLA-DR4)
  • “Streptococcal antibodies” against host tissues

300.3.1.2 Sydenham Chorea Pathophysiology

  • Anti-basal ganglia antibodies
  • Anti-D2 dopamine receptor antibodies
  • Carbonic anhydrase III
  • PANDAS / PANS (similar concept in children)

300.3.2 Recent Trials & Updates

300.3.2.1 Subclinical Carditis (2015 Jones Modification)

  • Echocardiographic screening in high-risk populations
  • Reveals more cases
  • Treatment decisions individualized

300.3.2.2 RHEUMATIC (2024) — RHD Vaccine

  • Multi-antigen vaccine candidates in trial
  • StreptAnova phase II
  • Hope for primary prevention

300.3.2.3 Penicillin Adherence Strategies

  • Implantable formulations in development
  • 6-12 month formulations being trialed
  • ↑ Compliance + ↓ ARF recurrence

300.3.2.4 Endemic Country Strategies

  • Australia: Aboriginal communities high burden
  • Pacific: similar
  • New Zealand: BPG availability
  • WHO RHD Action Plan 2024-2030

300.3.3 High-Yield Specialist Points

300.3.3.1 Carditis Severity Grading

  • Mild: subclinical or trivial murmur
  • Moderate: clear murmur + LV function preserved
  • Severe: HF, LV dysfunction

300.3.3.2 Anti-Inflammatory Choice

  • ASA still standard for arthritis (high-dose)
  • Naproxen also used
  • Steroids for HF, severe carditis (debated for valve protection)

300.3.3.3 Surgery + Pregnancy

  • Pregnancy + severe MS: PMBV during pregnancy
  • Pregnancy mWHO 2-4 for RHD
  • Anticoagulation considerations (warfarin teratogenic; LMWH for mechanical valve)

300.3.3.4 Newer Diagnostic Modalities

  • Handheld echocardiography
  • AI-assisted screening
  • Smartphone-based devices
  • Increasing access globally

300.3.3.5 Global Health Initiative

  • Penicillin G global access challenges
  • Generic shortages
  • Storage requirements
  • Workforce training for IM administration

300.3.3.6 Migration Health

  • Travelers / immigrants from endemic areas
  • Screening with echo
  • Continue prophylaxis

300.3.3.7 Vaccine Development

  • StreptAnova (multi-valent M protein)
  • C5a peptidase
  • Polysaccharide conjugates
  • Phase I-II trials
  • Decades-long effort

300.3.4 Pearls

  • ARF: 2-4 wk post-GAS pharyngitis; Jones criteria + GAS evidence
  • 5 major manifestations: carditis, migratory polyarthritis, Sydenham chorea, erythema marginatum, subcutaneous nodules
  • GAS pharyngitis: penicillin V or BPG; prevents ARF
  • Secondary prevention: BPG IM q3-4 wk; duration varies
  • RHD: MS most common; MR, AR, AS may coexist
  • 2015 Jones: subclinical carditis accepted for moderate/high-risk populations
  • 2024 RHD Action Plan: echo screening + penicillin access + vaccine R&D
  • Global burden: 33 million RHD prevalent; 470,000 new ARF/yr