What is the treatment for heart block caused by infectious diseases in pediatric patients?

Infectious Causes of Heart Block in Pediatric Patients and Treatment

The most critical infectious cause of heart block in pediatric patients is infective endocarditis (IE), which requires urgent antimicrobial therapy tailored to the causative organism, with acute onset of atrioventricular block being a red flag for periannular extension requiring surgical evaluation. 1

Primary Infectious Etiologies

Infective Endocarditis

• Acute onset of atrioventricular block in IE indicates periannular extension of infection, which typically does not respond to medical management alone and requires surgical intervention 1
• Heart block in IE suggests abscess formation, fistulous tracks, or extension beyond valve leaflets—all high-risk complications 1
• Congenital heart disease is the leading risk factor for pediatric IE in developed countries, making this population particularly vulnerable 2

Lyme Carditis

• Lyme disease is the most common vector-borne cause of heart block in endemic areas, affecting 4-10% of patients with Lyme disease 3
• Transient atrioventricular blocks occur in 77% of adults with Lyme carditis, with up to 50% developing complete heart block 3
• In children from endemic areas presenting with new high-grade heart block, Lyme disease testing is mandatory 4
• Predominantly affects adolescent males (mean age 15.9 years in one series) 4

MIS-C (Multisystem Inflammatory Syndrome in Children)

• Atrioventricular block occurs in up to 20% of children with MIS-C, including progression to second and third-degree block 1
• EKG is a key component of the diagnostic evaluation for all suspected MIS-C cases 1

Treatment Approach by Etiology

For Infective Endocarditis with Heart Block

Immediate Actions:

• Urgent cardiology and cardiac surgery consultation is mandatory when heart block develops in IE, as this indicates periannular extension 1
• Blood cultures before antibiotics (at least 3 sets from different sites) 1
• Echocardiography (transesophageal preferred in complex CHD or older children) to identify vegetations, abscesses, and fistulae 2

Antimicrobial Therapy:

For Streptococcal IE (most common in children):

• Penicillin G or ampicillin for 4-6 weeks for penicillin-susceptible strains (MIC ≤0.1 μg/mL) 1
• Add gentamicin for first 2 weeks if MIC 0.1-0.5 μg/mL 1
• For prosthetic material: extend to 6 weeks with gentamicin for first 2 weeks 1

For Staphylococcal IE (increasingly common):

• Vancomycin 15 mg/kg/dose IV every 6 hours for 2-6 weeks depending on source and complications 1
• Daptomycin 6-10 mg/kg/dose IV once daily is an alternative option 1
• Do NOT use clindamycin or linezolid if endocarditis or endovascular infection is suspected 1
• For prosthetic valve MRSA: vancomycin plus rifampin for ≥6 weeks plus gentamicin for 2 weeks 1

For Culture-Negative IE:

• Ampicillin-sulbactam 300 mg/kg/day IV in 4-6 divided doses plus gentamicin 3 mg/kg/day for 4-6 weeks 1
• Infectious diseases consultation is mandatory 1

For HACEK organisms:

• Ceftriaxone or cefotaxime alone for 4 weeks, or ampicillin plus gentamicin 1

Surgical Indications:

• Progressive heart failure with periannular extension requires urgent surgery 1
• Prosthetic valve infection with S. aureus should be considered for valve replacement in most cases 1
• Abscesses or fistulae typically require surgical intervention 1

For Lyme Carditis with Heart Block

Diagnostic Confirmation:

• Lyme serology (IgM and IgG) in any child from endemic area with unexplained heart block 3, 4
• Look for erythema migrans rash, arthritis, or neurologic symptoms 3

Treatment Protocol:

• Antibiotic therapy for 21-28 days provides complete resolution of heart block within 2-5 days 4
• Standard regimen: IV ceftriaxone or oral doxycycline (if age >8 years and stable) 4
• Isoproterenol may be needed for 3-4 days in symptomatic patients with very slow escape rates 4
• Temporary transvenous pacing rarely required (only 1/12 patients in recent series) 4
• Steroids do NOT appear to shorten time course and are not routinely recommended 4
• No patient with Lyme carditis requires permanent pacemaker—all resolve completely 4

For MIS-C with Heart Block

Diagnostic Workup:

• EKG and echocardiogram are mandatory components 1
• Troponin T and BNP/NT-proBNP levels help identify cardiac involvement 1
• SARS-CoV-2 serology (80-90% positive) and PCR testing 1

Management:

• Hospital admission required for monitoring and supportive care 1
• Treatment follows MIS-C protocols (IVIG, corticosteroids) rather than specific anti-arrhythmic therapy 1
• Close cardiac monitoring for progression to higher-grade block 1

Critical Pitfalls to Avoid

• Never dismiss new heart block as benign in a febrile child—always consider IE, especially with CHD 1, 2
• Do not delay surgical consultation when heart block develops in IE—this indicates periannular extension with high mortality risk 1
• In endemic areas, failure to test for Lyme disease delays definitive treatment that provides rapid resolution 4
• Avoid clindamycin or linezolid for suspected endocarditis even if MRSA is confirmed—these agents are inadequate for endovascular infections 1
• Do not use steroids empirically for Lyme carditis—antibiotics alone provide rapid resolution 4
• Echocardiography is mandatory in children with CHD and bacteremia >2-3 days to rule out IE 1