What is the management of congenital complete heart block (CHB)?

Management of Congenital Complete Heart Block (CHB)

Congenital complete heart block requires careful monitoring and management with pacemaker implantation for symptomatic patients or those with risk factors for poor outcomes. The approach varies based on whether the diagnosis is made prenatally or postnatally, and whether structural heart disease is present.

Prenatal Management

Diagnosis and Assessment

• Perform detailed fetal echocardiography to:
  • Evaluate for structural cardiac abnormalities
  • Assess ventricular rate and function
  • Look for signs of hydrops fetalis 1
• Screen for maternal autoimmune disease with anti-Ro/SSA and anti-La/SSB antibodies 1, 2
• Consider fetal karyotype if structural abnormalities are present 1

Risk Stratification

High-risk features associated with poor outcomes include:

• Fetal hydrops (strongest predictor of intrauterine death) 3
• Ventricular rate <55 beats per minute 4
• Presence of structural heart disease 4
• Gestational age <35 weeks 5

Interventions

• Position mother in left lateral decubitus position to relieve aortocaval compression 1
• For immune-mediated CHB:
  • Note that once third-degree AV block has developed, corticosteroid therapy has not shown significant benefit 1, 2
  • Hydroxychloroquine may have preventive effects but efficacy is still being studied 2
• For bradycardia with hydrops:
  • Consider beta-sympathomimetics to increase fetal heart rate 2, 3
  • In-utero therapy remains investigational 1

Delivery Planning

• Develop a multidisciplinary delivery plan involving cardiology, obstetrics, and neonatology
• Consider timing of delivery based on:
  • Fetal well-being
  • Cardiovascular profile score 6
  • Presence of high-risk features
• Avoid unnecessary emergency cesarean sections in preterm infants 5
• Administer antenatal steroids if preterm delivery is anticipated 5

Postnatal Management

Immediate Assessment

• Evaluate for symptoms of bradycardia (poor perfusion, hypotension)
• Assess heart rate, QRS complex width, and escape rhythm
• Screen for structural heart disease if not already done prenatally

Pacing Indications

1. Immediate pacing (within 24 hours) for:

   • Symptomatic bradycardia with hemodynamic compromise
   • Neonates with structural heart disease and CHB
   • Heart rate <55 bpm
   • Evidence of heart failure or hydrops 4

2. Delayed pacing for:

   • Asymptomatic patients with acceptable heart rates
   • Isolated CHB with narrow QRS complex and adequate escape rhythm 7

Pacing Approach

• Temporary pacing:

  • Epicardial pacing wires can be used for up to 30 days 4
  • Provides bridge to permanent pacemaker implantation

• Permanent pacemaker:

  • Single-chamber pacing is generally preferred initially 7
  • Consider epicardial approach in small infants
  • Echo guidance may be helpful for implantation 7
  • Epicardial lead placement is mandatory in patients with intracardiac shunts 7

Long-term Follow-up

Monitoring

• Regular assessment of:
  • Pacemaker function
  • Ventricular function (risk of dilated cardiomyopathy)
  • Growth and development

Outcomes

• Long-term survival is approximately 76.8% at 30 years 3
• Median time to pacemaker implantation is 2.6 years 3
• Dilated cardiomyopathy occurs in a minority of patients (approximately 7%) 3

Special Considerations

• Pregnancy: Isolated congenital CHB has favorable outcomes during pregnancy when the escape rhythm has a narrow QRS complex 7
• Sports/Activity: No restrictions for asymptomatic patients with well-functioning pacemakers
• Endocarditis prophylaxis: Recommended for patients with associated structural heart disease 7

Prognostic Factors

• Mortality is significantly higher in patients with:
  • Structural heart disease (particularly heterotaxy syndrome) 4
  • Prematurity before 35 weeks 5
  • History of hydrops fetalis 3, 4

Early recognition, appropriate risk stratification, and timely intervention are crucial for improving outcomes in congenital complete heart block.