What is the treatment for symptomatic bradycardia?

Treatment of Symptomatic Bradycardia

For symptomatic bradycardia, first-line treatment is atropine 0.5-1 mg IV, which may be repeated every 3-5 minutes to a maximum of 3 mg, followed by transcutaneous pacing if medications fail, and consideration of temporary transvenous pacing for persistent symptoms. 1

Initial Assessment and Management

• Symptomatic bradycardia presents with:

  • Altered mental status
  • Ischemic chest discomfort
  • Acute heart failure
  • Hypotension
  • Signs of shock
  • Lightheadedness or syncope
  • Increased work of breathing 1

• Before initiating treatment:

  • Identify and address reversible causes:
    • Medications (beta-blockers, calcium channel blockers, digoxin)
    • Electrolyte disturbances
    • Hypothyroidism
    • Acute myocardial ischemia/infarction (especially inferior MI)
    • Sleep apnea
    • Hypothermia
    • Infection 1

Pharmacological Management Algorithm

First-Line Therapy

• Atropine 0.5-1 mg IV
  • May repeat every 3-5 minutes to maximum of 3 mg
  • Administer in increments of 0.5 mg, titrated to achieve minimally effective heart rate (approximately 60 bpm) 2, 1
  • Important caveat: Doses less than 0.5 mg may paradoxically worsen bradycardia due to parasympathomimetic response 2, 3

Second-Line Therapies (if atropine ineffective)

• Dopamine 5-20 μg/kg/min IV infusion 1
• Epinephrine 2-10 μg/min IV infusion 1
• Isoproterenol 2-10 μg/min IV infusion (use with caution if coronary ischemia suspected) 1

Special Situations

• For beta-blocker or calcium channel blocker overdose:

  • Glucagon 3-10 mg IV bolus followed by infusion of 3-5 mg/h 1, 4
  • High-dose insulin therapy may be considered 1

• For heart transplant patients:

  • Atropine is ineffective due to denervation
  • Consider methylxanthines (theophylline or aminophylline) 1, 5

• For spinal cord injury-induced bradycardia:

  • Methylxanthines (aminophylline or theophylline) may be effective 1, 6, 5

Pacing Therapies

Transcutaneous Pacing

• Indicated when medications fail to improve symptomatic bradycardia 2, 1
• Apply transcutaneous patches immediately for high-risk patients
• Note: Associated with significant pain; consider sedation if patient is conscious

Temporary Transvenous Pacing

• Consider for persistent hemodynamically unstable bradycardia refractory to medical therapy 1
• Particularly indicated for:
  • Sinus bradycardia (rate <50 bpm) with symptoms unresponsive to drug therapy
  • Symptomatic bradycardia not responsive to atropine
  • Bilateral bundle branch block
  • New or indeterminate age bifascicular block with first-degree AV block
  • Mobitz type II second-degree AV block 2

Important Considerations and Pitfalls

• Location of heart block matters:

  • Atropine is effective for AV block at the nodal level (second-degree type I or third-degree with narrow-complex escape rhythm)
  • Atropine may worsen or be ineffective for infranodal blocks (usually associated with anterior MI with wide-complex escape rhythm) 2, 3

• Atropine in acute MI:

  • Use with caution due to protective effect of parasympathetic tone against VF and myocardial infarct extension
  • Most effective for sinus bradycardia occurring within 6 hours of symptom onset 2

• Continuous monitoring:

  • All patients with bradycardia should be continuously monitored until stable
  • Regularly assess vital signs, symptoms, and monitor for adverse effects of medications 1

• Avoid temporary pacing in patients with minimal/infrequent symptoms without hemodynamic compromise 1

By following this structured approach to managing symptomatic bradycardia, clinicians can effectively improve patient outcomes while minimizing complications related to both the bradycardia itself and its treatment.