At the Bedside

Start with ABCs, monitor, IV access, and a 12-lead ECG. Ask: is the patient unstable from the bradycardia? Look for hypotension, altered mental status, ischemic chest pain, acute heart failure, syncope, or shock. If unstable, treat immediately while preparing pacing.

Key differential: sinus bradycardia, sick sinus syndrome, 1st/2nd/3rd-degree AV block, junctional rhythms, hypothermia, hypothyroidism, hyperkalemia, inferior MI, medication/toxin effect (beta-blockers, calcium channel blockers, digoxin, clonidine, opioids), increased vagal tone, and post-arrest states.

Workup:
  • ECG: identify rhythm, PR/QRS width, AV dissociation, escape rhythm, ischemic changes, hyperkalemic signs.
  • POC glucose, electrolytes, Mg, Ca, renal function.
  • Troponin if ischemia suspected.
  • TSH if clinically suggested, but don’t delay resuscitation.
  • Consider digoxin level, tox screen, ABG/VBG, temperature, pregnancy test when relevant.
  • Bedside ultrasound can help assess perfusion, volume status, and alternate shock states.
Management:
  • Unstable bradycardia: atropine first, but do not linger if high-grade block or poor response is likely. Move early to transcutaneous pacing and/or epinephrine or dopamine infusion.
  • Correct reversible causes: treat hyperkalemia, stop offending meds, warm hypothermic patients, manage MI, reverse overdoses when indicated.
  • High-grade AV block, Mobitz II, complete heart block, wide escape rhythms, or bradycardia with shock generally need urgent pacing and admission/ICU.
  • Symptomatic but stable patients still need close monitoring, repeat ECGs, and disposition based on cause and conduction pattern.
Disposition:
  • Stable sinus bradycardia from athletic conditioning or sleep may be discharged if clearly benign.
  • Otherwise admit/observe, and if pacing or pressors are required, ICU/CCU.
A Classic Presentation
A 72-year-old man with a history of hypertension and prior inferior MI presents after a syncopal episode while gardening. He is pale, diaphoretic, and hypotensive with a heart rate in the 30s. ECG shows complete heart block with a wide ventricular escape rhythm. Despite a dose of atropine, he remains symptomatic, so transcutaneous pacing is initiated while cardiology is paged for temporary transvenous pacing and ICU admission.
Patient Presentation to Attending
How you’d present this patient on the floor
This is a 72-year-old man with prior MI and beta-blocker use presenting after syncope with persistent bradycardia for the last hour. My main concern is hemodynamically significant bradycardia from high-grade AV block, because he’s hypotensive and had a transient loss of consciousness, which makes this more than benign sinus bradycardia. He’s had no clear reversible trigger like hypoglycemia or hypothermia, and he denies chest pain, but the ECG shows complete heart block with a wide escape rhythm. On exam he’s pale and diaphoretic with weak pulses and ongoing dizziness. Given the instability and poor expected atropine response in infranodal block, we’re moving to pacing now while checking electrolytes and ischemia labs and involving cardiology/ICU for likely temporary pacing and admission.

Study Directive

  • Draw the ACLS bradycardia algorithm from memory, including when to skip to pacing.
  • Review 10 ECGs: sinus bradycardia, junctional rhythm, Mobitz I, Mobitz II, complete heart block, hyperkalemia.
  • Practice a one-minute oral plan for unstable bradycardia: monitor, IV, ECG, atropine, pacing, pressors, reversible causes.
  • Memorize the common bradycardia mimics and medication/toxin triggers.
  • Read your institution’s transcutaneous pacing setup steps and sedation approach.

Recent Literature