What is the treatment for complete heart block?

Treatment of Complete Heart Block

Permanent pacemaker implantation is the definitive treatment for complete heart block, especially when symptomatic or associated with hemodynamic compromise. 1

Indications for Permanent Pacing in Complete Heart Block

Class I Indications (Definite Benefit)

• Complete heart block with any of the following:
  • Symptomatic bradycardia (syncope, near-syncope, dizziness, confusion)
  • Congestive heart failure
  • Documented periods of asystole ≥3.0 seconds
  • Escape rate <40 beats/min in asymptomatic patients
  • Confusional states that clear with temporary pacing
  • Need for medications that suppress escape pacemakers
  • Post-AV junction ablation or in myotonic dystrophy 1

Class IIa Indications (Reasonable Benefit)

• Asymptomatic complete heart block with ventricular rates ≥40 beats/min 1
• Persistent advanced AV block after myocardial infarction with block in His-Purkinje system 1

Acute Management Before Pacemaker Implantation

For symptomatic patients awaiting permanent pacemaker implantation:

1. Temporary pacing may be required for hemodynamic stabilization
2. Pharmacologic support with:
   • Atropine for temporary increase in heart rate
   • Isoproterenol infusion for temporary chronotropic support
   • Dobutamine for inotropic and chronotropic support 2
3. External transcutaneous pacing should be available as standby

Pacemaker Selection and Implantation Considerations

Device Selection

• Dual-chamber pacing (DDD/DDDR) is preferred for most patients to maintain AV synchrony
• Single-chamber ventricular pacing (VVI/VVIR) may be appropriate for:
  • Patients with permanent atrial fibrillation
  • Elderly patients with limited physical activity
  • Situations where venous access is limited

Special Considerations

• For patients with LV dysfunction: Consider biventricular pacing (CRT) to avoid right ventricular pacing-induced dyssynchrony 1, 3
• For congenital complete heart block: Pacing is indicated for symptomatic patients or infants with heart rates <55 bpm (or <70 bpm with structural heart disease) 1
• For post-surgical AV block: Permanent pacing is indicated if block persists for ≥7 days after cardiac surgery 1

Prognostic Implications

Permanent pacing significantly improves survival in patients with complete heart block, particularly when syncope has occurred 1. However, long-term outcomes depend on:

• Presence of coexisting heart disease (poorer prognosis)
• Age (patients ≥80 years have worse outcomes than age-matched controls even with isolated AV block)
• Comorbidities (CHF, COPD, diabetes are independent predictors of increased mortality) 4

Common Pitfalls and Caveats

1. Reversible causes of AV block should be ruled out before permanent pacemaker implantation:

   • Electrolyte abnormalities
   • Drug toxicity (beta-blockers, calcium channel blockers, digoxin)
   • Lyme disease
   • Perioperative inflammation near the conduction system

2. Procedural complications to be aware of:

   • Pneumothorax during subclavian vein access
   • Lead dislodgement
   • Pocket hematoma or infection
   • Venous thrombosis

3. Risk factors for developing complete heart block after procedures:

   • Pre-existing bundle branch block
   • First-degree AV block
   • Female gender 5

4. Pacemaker syndrome may develop in patients with single-chamber ventricular pacing due to loss of AV synchrony, requiring upgrade to dual-chamber system

Complete heart block requires prompt recognition and appropriate treatment with permanent pacing to prevent morbidity and mortality from bradycardia-related complications.