Complete (Third-degree) Heart Block

Conduction

Recognition

  • AV dissociation — P and QRS independent
  • Atrial rate > ventricular rate
  • Ventricular escape 20–40 bpm (wide) or 40–60 (narrow)

Key findings

  • Cannon A waves on JVP

Clinical importance

  • Risk of haemodynamic collapse / Stokes-Adams attacks

Management pearls

  • Atropine 500 mcg IV (often ineffective)
  • Isoprenaline / adrenaline infusion
  • Transcutaneous pacing → transvenous → permanent pacemaker
WardRound

WardRound

Clinical Decisions in Seconds