Medicine · Arrhythmias and Conduction Disorders (ECG, Tachycardia, Heart Block)

A 75-year-old man with complete heart block (CHB) develops syncope. His resting ECG shows P waves at 72 bpm with complete AV dissociation and an escape rhythm at 34 bpm (wide QRS). What is the IMMEDIATE definitive treatment?

  • A IV atropine 1 mg bolus
  • B IV dopamine infusion at 5 mcg/kg/min
  • C Permanent pacemaker implantation (Class I indication)
  • D Temporary transvenous pacing followed by permanent pacemaker implantation
Correct answer: D. Temporary transvenous pacing followed by permanent pacemaker implantation

Explanation

Symptomatic complete heart block with syncope and a slow ventricular escape rate (34 bpm) requires urgent temporary transvenous pacing to stabilize the patient, followed by permanent pacemaker implantation (Class I indication per ACC/AHA guidelines). While transcutaneous pacing may provide brief stabilization, transvenous pacing is the definitive bridge to permanent pacing. Atropine is unreliable for infranodal (His-Purkinje) block (wide QRS escape indicates infranodal site) and is only partially effective for AV nodal block. Dopamine may increase rate but is not definitive. Immediate permanent pacemaker without temporary pacing is feasible in stable patients but emergency stabilization must occur first.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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