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Case 021: Infective Endocarditis in Repaired CHD

Clinical Presentation

Setting: Pediatric emergency department

Patient: 14-year-old male with history of repaired tetralogy of Fallot

Surgical History: - Age 6 months: Complete TOF repair with transannular patch - Age 10: Pulmonary valve replacement (25mm Hancock bioprosthetic)

Chief Complaint: Fever for 3 weeks, fatigue, decreased appetite

History of Present Illness: The patient has had intermittent fevers (up to 39.2°C) for the past 3 weeks. Initially attributed to viral illness, but fevers persisted despite supportive care. He reports significant fatigue, 5-pound weight loss, night sweats, and decreased appetite. He had a dental cleaning 6 weeks ago and admits he did not take prophylactic antibiotics because "they forgot to call them in."

Two days ago, he noticed painful red spots on his fingertips. Today his mother noticed he seemed confused, prompting ED visit.

Initial Assessment

Vital Signs: - Temperature: 38.9°C - HR: 112 - BP: 102/58 - RR: 22 - SpO2: 96% on RA

Physical Exam: - General: Ill-appearing, diaphoretic adolescent - HEENT: Petechiae on conjunctivae bilaterally, poor dentition with visible caries - Cardiac: Regular tachycardia, 3/6 systolic ejection murmur at LUSB (baseline), NEW 2/6 diastolic murmur - Lungs: Clear to auscultation - Abdomen: Splenomegaly (4cm below costal margin), mildly tender - Extremities: Splinter hemorrhages in nail beds, 2 Osler nodes on finger pads - Skin: No Janeway lesions - Neuro: Mild word-finding difficulty, otherwise intact

Diagnostic Workup

Laboratory Studies:

Test Result Reference
WBC 18.2 × 10⁹/L 4.5-11.0
Hemoglobin 9.8 g/dL 12-16
Platelets 142 × 10⁹/L 150-400
ESR 78 mm/hr 0-15
CRP 142 mg/L <5
Procalcitonin 2.8 ng/mL <0.1
Creatinine 1.4 mg/dL 0.5-1.0
Urinalysis RBC casts, proteinuria -

Blood Cultures: 3 sets drawn from separate sites

ECG: - Sinus tachycardia, rate 115 - RBBB (baseline) - No new conduction abnormalities

Echocardiogram:

Finding Description
Bioprosthetic PV 12mm × 8mm mobile, oscillating mass on ventricular surface
Pulmonary regurgitation Moderate (increased from prior mild)
RV function Mildly reduced (TAPSE 14mm)
No abscess No evidence of paravalvular involvement
No new PR or RVOT obstruction Valve leaflets mobile

Case Progression

Blood Culture Results (48 hours)

All 3 sets positive: Viridans group streptococci (Streptococcus mitis) - MIC to penicillin: 0.06 mcg/mL (susceptible) - Susceptible to ceftriaxone, vancomycin

Decision Point 1

What is your diagnosis using Duke Criteria?

Answer

DEFINITE Infective Endocarditis

Major Criteria (2/2):

  1. ✓ Positive blood cultures: Typical organism (viridans strep) from 3 separate cultures
  2. ✓ Echocardiographic evidence: Vegetation on prosthetic valve

Minor Criteria (4/5):

  1. ✓ Predisposing condition (prosthetic valve)
  2. ✓ Fever >38°C
  3. ✓ Vascular phenomena (splinter hemorrhages, possible embolic stroke)
  4. ✓ Immunologic phenomena (Osler nodes, glomerulonephritis with RBC casts)
  5. ✗ Blood cultures not meeting major (N/A - already meets major)

Diagnosis: 2 major criteria = Definite IE

Decision Point 2

What is your initial antibiotic regimen?

Answer

For prosthetic valve viridans streptococcal IE (penicillin-susceptible):

Penicillin G 300,000 units/kg/day IV divided q4h
(max 24 million units/day)

PLUS

Gentamicin 3 mg/kg/day IV divided q8h × 2 weeks
(for synergy)

Alternative: Ceftriaxone 100 mg/kg/day (max 4g) if penicillin allergy

Duration: 6 weeks total (prosthetic valve)

Key Points: - Prosthetic valve = 6 weeks minimum (not 4) - Gentamicin added for synergy (only 2 weeks, monitor levels/renal function) - Could have started empiric vancomycin + gentamicin pending cultures

Case Progression - Day 3

The patient's mental status has returned to baseline. MRI brain obtained:

MRI Brain Findings: - Multiple small acute ischemic infarcts in MCA distribution bilaterally - No hemorrhagic transformation - No mycotic aneurysm identified on MRA

Clinical Status: - Afebrile for 48 hours on antibiotics - Repeat blood cultures at 48h: No growth to date - Hemodynamically stable - Vegetation size unchanged on repeat echo

Decision Point 3

Does this patient need surgery? When?

Answer

Current Surgical Indications - NOT immediately met:

Indication This Patient
Heart failure from valve dysfunction No - hemodynamically stable
Persistent sepsis >5-7 days No - afebrile, cultures clearing
Abscess No
Fungal IE No - streptococcal
Large vegetation + emboli YES - 12mm vegetation with CNS emboli

Recommendation: Surgery is relatively indicated (Class IIa) due to: - Large vegetation (>10mm) - Documented embolic event (stroke) - Prosthetic valve involvement

Timing: Given recent ischemic stroke WITHOUT hemorrhage: - May proceed with surgery within 1-2 weeks if clinically needed - If hemorrhagic stroke: delay 4 weeks

This Patient: Continue antibiotics, surgical consultation. If vegetation enlarges, recurrent emboli, or hemodynamic deterioration → operate. Otherwise, reasonable to complete antibiotics with close monitoring given clinical improvement.

Case Progression - Day 10

Repeat Echocardiogram: - Vegetation now 8mm (decreased from 12mm) - Moderate PR unchanged - RV function stable - No abscess

Clinical Status: - Afebrile since day 2 - Repeat blood cultures negative - Creatinine normalized to 0.8 mg/dL - ESR/CRP trending down - Neurologically at baseline

Team Decision: Continue medical management with 6-week antibiotic course. Will need future PVR given underlying prosthetic valve IE, but not emergently.

Discharge Planning

Week 3 - Transition to OPAT:

Criteria met: - ✓ Clinically stable, afebrile >1 week - ✓ Cultures negative - ✓ CRP normalizing - ✓ No surgical indication - ✓ PICC line placed - ✓ Family education completed - ✓ Home nursing arranged

Outpatient Antibiotic Plan: - Ceftriaxone 2g IV daily (switched from penicillin for once-daily dosing) - Remaining 3 weeks as outpatient

Follow-up: - Weekly labs: CBC, BMP, CRP - Weekly ID/Cardiology phone check - Echo at end of therapy - Return precautions reviewed

Long-Term Outcomes

End of Therapy (6 weeks): - Echo: Vegetation resolved, moderate PR, no abscess - CRP: <5 mg/L - Blood cultures: Negative

6-Month Follow-up: - No recurrence - Exercise tolerance improved - Planning for pulmonary valve re-replacement in 1-2 years due to progressive PR

Lifelong Requirements: - IE prophylaxis for ALL dental procedures - Dental care optimization - Education on fever workup

Teaching Points

Key Lessons from This Case

  1. Prophylaxis failure: Patient did not receive prophylaxis before dental procedure - emphasize importance

  2. Classic presentation: Subacute course (3 weeks), constitutional symptoms, embolic phenomena (stroke, Osler nodes, splinter hemorrhages, glomerulonephritis)

  3. Duke criteria application: 2 major = definite IE

  4. Prosthetic valve = 6 weeks: Native valve strep IE can be 4 weeks; prosthetic always 6

  5. Vegetation >10mm with emboli: Relative surgical indication, but can be managed medically if responding

  6. Stroke timing for surgery:

  7. Ischemic only: can operate within 1-2 weeks

  8. Hemorrhagic: delay 4 weeks

  9. OPAT is appropriate: Stable patients can complete therapy at home with proper infrastructure

  10. Dental health matters: Poor dentition was a risk factor; optimize dental care

References

  1. Baltimore RS, et al. Infective Endocarditis in Childhood: 2015 Update. Circulation. 2015.
  2. Baddour LM, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications. Circulation. 2015.
  3. Habib G, et al. 2015 ESC Guidelines for the Management of Infective Endocarditis. Eur Heart J. 2015.