What is the management of complete heart block?

Management of Complete Heart Block

Permanent pacemaker implantation is recommended for patients with complete heart block who are symptomatic or have hemodynamic compromise. 1

Diagnosis and Assessment

• Complete heart block (third-degree AV block) is defined as the complete absence of AV conduction
• Clinical presentation varies based on:
  • Escape rhythm characteristics (rate, QRS width)
  • Presence of underlying heart disease
  • Hemodynamic stability
  • Associated symptoms

Key Diagnostic Findings

• ECG showing AV dissociation with:
  • Regular P waves
  • Independent ventricular rhythm (typically 20-40 bpm)
  • No relationship between P waves and QRS complexes

Management Algorithm

1. Immediate Management of Acute Complete Heart Block

• For hemodynamically unstable patients:

  • Administer atropine 0.5-1.0 mg IV (may repeat up to total dose of 1.5-2.0 mg) 1, 2
    • Note: Atropine is often ineffective in infra-His blocks but may help in AV nodal blocks
  • If no response to atropine, initiate temporary pacing:
    • Transcutaneous pacing for immediate support
    • Transvenous temporary pacing if persistent instability

• For hemodynamically stable patients:

  • Close monitoring with continuous ECG
  • IV access and preparation for emergency interventions
  • Identify and treat reversible causes (drug toxicity, electrolyte abnormalities)

2. Definitive Management

Class I Indications for Permanent Pacemaker (Strong Recommendation):

• Complete heart block with any of the following 1:
  • Symptomatic bradycardia
  • Wide QRS escape rhythm
  • Mean daytime heart rate below 50 bpm
  • Complex ventricular ectopy
  • Ventricular dysfunction

Class IIa Indications (Reasonable to Perform):

• Asymptomatic congenital complete heart block 1
• Postoperative complete heart block not expected to resolve 1

3. Special Considerations

Congenital Complete Heart Block

• Isolated congenital complete heart block has favorable outcomes during pregnancy when escape rhythm has narrow QRS complex 1
• Supportive pacing during pregnancy usually not necessary unless symptoms develop 1

Perioperative Management

• For pregnant women with complete heart block, temporary pacing during delivery is recommended in those with symptoms 1
• Permanent pacemaker implantation can be performed safely during pregnancy, especially beyond 8 weeks gestation 1
• Echo guidance may be helpful for implantation during pregnancy 1

Post-Cardiac Surgery

• Complete heart block after cardiac surgery requires observation as it may resolve
• Permanent pacing is indicated if complete heart block persists and is not expected to resolve 1

Technical Aspects of Pacemaker Implantation

• Pacemaker implantation is typically performed under local anesthesia with conscious sedation
• Access is usually via the subclavian or axillary vein (93.6% of cases) 3
• Potential complications include:
  • Pneumothorax (0.8% requiring treatment) 3
  • Lead displacement (1.4%, more common with atrial leads) 3
  • Pocket infection (0.9%, higher risk with prior temporary pacing) 3

Follow-up Care

• Initial device check within 2-4 weeks of implantation
• Regular follow-up every 3-12 months based on device type and patient characteristics
• Remote monitoring when available
• Patient education regarding:
  • Activity restrictions during healing period
  • Electromagnetic interference precautions
  • Signs of infection or device malfunction

Pitfalls and Caveats

• Do not delay permanent pacemaker implantation in symptomatic patients with complete heart block
• Avoid assuming all bradycardias in AF represent complete heart block; a slow, regular ventricular response during AF usually indicates complete heart block 1
• Temporary pacing should not be used as a long-term solution for permanent complete heart block
• In patients with complete heart block and structural heart disease, consider whether an ICD rather than a pacemaker is indicated if risk factors for sudden cardiac death are present 1