Infective Endocarditis

IE Basics & Etiology - Heart's Unwanted Guests

• Infection of endocardium, valves, or devices.
• Etiology:
  • Mainly bacterial; fungi rare.

  ⭐ Staphylococcus aureus is the most common causative organism of infective endocarditis in children, particularly with intravascular catheters or post-cardiac surgery.

  • S. viridans (post-dental).
  • HACEK group (📌 Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella).
  • CoNS (prosthetic valves/devices).
• Risk Factors (Pediatrics):
  • CHD (most common).
  • RHD.
  • Central venous catheters.
  • Previous cardiac surgery.
  • Immunocompromised state_

IE Pathophysiology - Attack on the Valves

⭐ The formation of vegetations in infective endocarditis typically begins with endothelial damage, leading to a non-bacterial thrombotic endocarditis (NBTE) nidus, which is then colonized by bacteria during transient bacteremia.

IE Clinical Features - Signs of Siege

• Systemic: Persistent fever (often > 38°C), chills, malaise, weight loss, arthralgia.
• Cardiac:
  • New or changing heart murmur (most specific sign).
  • Signs of heart failure (tachycardia, tachypnea, hepatomegaly).
• Peripheral Stigmata (📌 FROM JANE):
  • Fever
  • Roth spots (retinal hemorrhages)
  • Osler nodes (painful, tender nodules on digits)
  • Murmur (new/changed)
  • Janeway lesions (painless, erythematous macules on palms/soles)
  • Anemia
  • Nail-bed (splinter) hemorrhages
  • Emboli (septic; to brain, spleen, kidney, etc.)
• Other: Splenomegaly, clubbing (late finding).

⭐ A new or changing heart murmur is a hallmark clinical finding in pediatric infective endocarditis and should prompt further investigation.

IE Diagnosis - The Evidence Trail

• Blood Cultures: 3 sets, different sites, 1hr apart, pre-antibiotics.
• Echo: TTE → TEE. Shows vegetations, abscess, new regurgitation.
• Modified Duke Criteria: IE = 2M / 1M+3m / 5m.
• Other: CBC (anemia), ↑ESR/CRP.

⭐ The Modified Duke Criteria are essential for diagnosing infective endocarditis, with positive blood cultures for typical organisms and echocardiographic evidence of endocardial involvement being the two major criteria.

IE Management & Prophylaxis - Shielding the Heart

• Management:

  • Goals: Eradicate infection, manage complications.
  • Antibiotics:
    • Empirical: Vancomycin + Gentamicin.
    • Culture-directed: 4-6 weeks (Native Valve Endocarditis - NVE), ≥6 weeks (Prosthetic Valve Endocarditis - PVE).
  • Surgery Indications: Heart Failure (HF), fungal IE, persistent sepsis, large vegetations (>10mm) + emboli, perivalvular abscess.

• Prophylaxis:

  • High-Risk Patients Only: Prosthetic valves, prior IE, specific Congenital Heart Diseases (CHDs) (unrepaired cyanotic; repaired <6 months with prosthetic material or device; repaired with residual defect), cardiac transplant recipients with valvulopathy.
  • High-Risk Procedures:
    • Dental: Gingival/periapical manipulation, oral mucosa perforation.
    • Respiratory Tract: Incision/biopsy of mucosa (e.g., tonsillectomy, adenoidectomy).
  • Regimen: Amoxicillin 50 mg/kg (max 2g) orally 30-60 minutes before procedure.
    • Penicillin allergy: Clindamycin 20 mg/kg (max 600mg) or Azithromycin/Clarithromycin 15 mg/kg (max 500mg).

⭐ Antibiotic prophylaxis for infective endocarditis is recommended only for the highest-risk pediatric patients (e.g., those with prosthetic cardiac valves or previous IE) undergoing specific dental procedures involving gingival manipulation or respiratory tract incisions.

High‑Yield Points - ⚡ Biggest Takeaways

• Most common organisms: Staphylococcus aureus; Viridans streptococci with underlying CHD.
• Congenital Heart Disease (CHD) is the major predisposing factor in pediatrics.
• Diagnosis uses Modified Duke Criteria; echocardiography confirms vegetations.
• Obtain multiple blood cultures (ideally 3 sets) before starting antibiotics.
• Antibiotic prophylaxis is vital for high-risk CHD patients during certain procedures.
• Empirical treatment: Typically Vancomycin plus Gentamicin.
• Key complications include septic emboli and congestive heart failure.