What are the indications for a pacemaker?

Indications for Pacemaker Implantation

Pacemakers are primarily indicated for symptomatic bradycardia due to sinus node dysfunction or AV block, with specific Class I indications including second or third-degree AV block with symptomatic bradycardia, advanced heart block with exercise intolerance, and sinus node dysfunction with symptomatic bradycardia. 1

Primary Indications (Class I)

Atrioventricular (AV) Block

• Second or third-degree AV block with symptomatic bradycardia 1
• Advanced second or third-degree AV block with moderate to marked exercise intolerance 1
• Complete heart block (permanent or intermittent) with any of the following:
  • Symptomatic bradycardia
  • Congestive heart failure
  • Documented asystole ≥3.0 seconds or escape rate <40 beats/min in asymptomatic patients
  • Confusional states that clear with temporary pacing 1

Sinus Node Dysfunction

• Sinus node dysfunction with symptomatic bradycardia 1
• Correlation of symptoms during age-inappropriate bradycardia (particularly important in pediatric patients) 1

Post-Surgical and Congenital Conditions

• Advanced second or third-degree AV block persisting 10-14 days after cardiac surgery 1
• Congenital third-degree AV block with wide QRS escape rhythm or ventricular dysfunction 1
• Congenital AV block with wide QRS escape rhythm or block below the His bundle 1

Special Circumstances

• External ophthalmoplegia with bifascicular block 1
• Post AV junction ablation 1

Secondary Indications (Class II)

• Asymptomatic complete heart block with ventricular rates ≥40 beats/min 1
• Asymptomatic type II second-degree AV block 1
• Bradycardia-tachycardia syndrome requiring antiarrhythmic drugs other than digitalis or phenytoin 1
• Second or third-degree AV block within the bundle of His in asymptomatic patients 1
• Asymptomatic second or third-degree AV block with ventricular rate <45 beats/min when awake 1
• Long QT syndrome 1

Pacing for Tachyarrhythmias

• Symptomatic recurrent supraventricular tachycardia when drugs fail or produce intolerable side effects 1
• Symptomatic recurrent ventricular tachycardia after defibrillator implantation when drugs fail 1
• Recurrent supraventricular tachycardia as an alternative to drug therapy 1

Contraindications (Class III)

• Asymptomatic patients or those whose symptoms are medically controlled 1
• First-degree AV block 1
• Tachycardias that are accelerated or converted to fibrillation by pacing 1
• Presence of accessory pathways with rapid anterograde conduction capacity 1

Special Considerations in Pediatric Patients

Pacemaker implantation in children requires special considerations:

• Symptomatic bradycardia definition varies with age and expected heart rate 1
• Congenital heart disease with bradycardia requires careful evaluation 1
• Bradycardia-tachycardia syndrome is a frequent indication, particularly when antiarrhythmic drugs are needed 1

Clinical Pearls and Pitfalls

• Important pitfall: Temporary pacing during acute myocardial infarction does not by itself constitute an indication for permanent pacing 1
• Key consideration: In patients with complete heart block, symptoms must be presumed due to heart block unless proven otherwise 1
• Critical assessment: Before pacemaker implantation for carotid sinus syndrome, it's essential to define if there's a vasodepressor component to the reflex response 1
• Monitoring approach: In children, concurrence of symptoms with bradycardia can be determined by 24-hour ambulatory ECG or transtelephonic ECG 1

Pacemaker therapy has evolved significantly from treating simple bradycardia to addressing complex arrhythmias and heart failure, with demonstrated benefits in reducing symptoms like fatigue, dizziness, and syncope while improving quality of life and reducing mortality in specific patient populations 2, 3.