Management of bradycardia

Bradycardia is generally defined as a heart rate of < 60/min. The most important step in the acute management of bradycardia is determining if the patient is unstable, in which case atropine should be administered immediately. If IV access is not available and the patient is unstable, transcutaneous pacing should be initiated. The management of symptomatic, stable bradycardia is similar but should be tailored to the suspected cause of the bradycardia. Asymptomatic, stable bradycardia typically does not require treatment. Definitive management depends on the underlying cause of the bradycardia.

See also overview of cardiac arrhythmias, sick sinus syndrome, and atrioventricular block.

1. ABCDE survey ^[1]

• No pulse: Start CPR (see ACLS).
• Pulse present: Continue stepwise approach through ABCDE survey and proceed to the next step.
• Identify and treat hypoxemia: supplemental oxygen to goal S_pO₂ > 94% ^[1]
• Obtain a 12-lead ECG (only if immediately available)
• Monitoring and supportive care
  • Continuous cardiac monitoring
  • Continuous pulse oximetry
  • Crash cart at the bedside
  • Frequent blood pressure assessment
  • IV access

2. Determine if the patient is stable or unstable ^[1]

• Signs of unstable bradycardia present: Administer atropine. ^[1][2]
  • If atropine is ineffective, prepare for emergency transvenous pacing and follow the algorithm for unstable bradycardia.
• No signs of unstable bradycardia present: Proceed to the next step.

Obtaining an ECG to identify the rhythm should not delay the acute management of unstable patients.

3. Determine if the patient is symptomatic or asymptomatic

• Symptomatic, stable bradycardia: Most patients can be observed and will not require intervention.
  • Patients with severe symptoms: Administer atropine. ^[1]
  • If second-degree AV block, Mobitz II, or third-degree AV block is present and the patient is symptomatic: Start transcutaneous pacing or transvenous pacing.
• Asymptomatic bradycardia: Usually, no treatment is required.
  • If second-degree AV block, Mobitz II, or third-degree AV block is present: Consider transcutaneous pacing or transvenous pacing.

Overview of bradycardia based on ECG findings

Signs of unstable bradycardia

• Signs of hypoperfusion
• Respiratory distress
• Chest pain
• Pulmonary edema
• Shock
• Altered mental status

Initial management ^[1]

• If IV access is available, give atropine. ^[1][2]
  • If atropine is ineffective, prepare for emergency transvenous pacing while considering the following temporizing measures:
    • Epinephrine ^[1]
    • Dopamine ^[1][2]
    • Isoproterenol ^[1]
    • Transcutaneous pacing
• If IV access is not available, begin transcutaneous pacing. ^[3]
• Identify and treat hypoxemia: supplemental oxygen to S_pO₂ > 94%

Transcutaneous pacing

• Consider procedural sedation.
• Place the leads in the anteroposterior position.
• Set output to a level that is likely to result in capture.
  • Unconscious patient: Start at 160–180 mA and decrease output if possible.
  • Conscious patient: Start at a low output (e.g., 10 mA) and gradually increase until capture is seen.
• Set pacing rate to 60–80/min.
• Set a backup rate at a low level to avoid unnecessary pacing (e.g., 30/min).
• Verify ventricular capture by checking the patient's pulse manually or with pulse oximetry.

Most patients can be observed and will not require intervention; only patients with high-grade AV block or severe symptoms should be treated.

Initial management ^[2]

• First-line: atropine (unless acute MI is suspected or the patient has had a recent heart transplant) ^[2]
• If atropine is ineffective and the patient continues to have severe symptoms, prepare for transvenous pacing and follow the algorithm for unstable bradycardia.
• Identify and treat hypoxemia: supplemental oxygen to S_pO₂ > 94%

Avoid atropine in patients with myocardial infarction or a recent heart transplant.

• Usually, no treatment is required.
• Second-degree AV block, Mobitz II, or third-degree AV block: Consider transcutaneous or transvenous pacing therapy regardless of symptoms.
• Identify and treat the underlying cause (see causes of bradycardia).
• Identify and treat hypoxemia: supplemental oxygen to S_pO₂ > 94%
• Consider TTE.
• Cardiology consult for consideration of further evaluation.
  • Prolonged monitoring (e.g., Holter monitoring): if a bradyarrhythmia is strongly suspected but cannot be captured on normal ECG
  • Long-term event monitor or loop recorder: if AV block or sinus pause/arrest is suspected
  • Electrophysiologic study

Consider pacing therapy even in asymptomatic patients with second-degree AV block, Mobitz II, or third-degree AV block.

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