What is the treatment for symptomatic bradycardia?

Treatment of Symptomatic Bradycardia

For symptomatic bradycardia, atropine 0.5-1 mg IV is the first-line treatment, repeating every 3-5 minutes as needed up to a maximum total dose of 3 mg. 1

Initial Assessment and Management

• Evaluate if bradycardia is causing symptoms or hemodynamic compromise (altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or shock) 1
• Maintain patent airway, assist breathing if necessary, and provide supplemental oxygen if hypoxemic 1
• Establish cardiac monitoring to identify rhythm, monitor blood pressure, and measure oxygen saturation 1
• Establish IV access for medication administration 1
• Obtain a 12-lead ECG if available 1

Treatment Algorithm

First-Line Treatment

• Administer atropine 0.5-1 mg IV for symptomatic bradycardia 1, 2
• Repeat every 3-5 minutes as needed up to a maximum total dose of 3 mg 1
• Avoid doses of atropine <0.5 mg as they may paradoxically worsen bradycardia due to central vagal stimulation 3, 4

If Bradycardia Persists Despite Atropine

• Initiate IV infusion of β-adrenergic agonists: 1
  • Dopamine (5-10 mcg/kg/min, titrated according to response) 1
  • Epinephrine (0.1-0.5 mcg/kg/min) 1
  • Isoproterenol (for AV block with low likelihood of coronary ischemia) 3
• Consider transcutaneous pacing in unstable patients who do not respond to atropine 1
• Prepare for transvenous pacing if the patient does not respond to drugs or transcutaneous pacing 1

Oral Medication Option

• Theophylline (aminophylline) may be considered for persistent symptomatic bradycardia, particularly in:
  • Patients with sinus node dysfunction 3
  • After inferior myocardial infarction 3
  • Cardiac transplant patients 3, 5
  • Patients with spinal cord injury 3, 5

Special Considerations

Type of AV Block

• Atropine is likely effective in sinus bradycardia, AV nodal block, or sinus arrest 1
• Atropine may be ineffective or harmful in type II second-degree or third-degree AV block with new wide-QRS complex (infranodal block) 1, 4

Specific Clinical Scenarios

• Avoid atropine in heart transplant patients without evidence of autonomic reinnervation, as it may cause paradoxical high-degree AV block 3, 1
• Use atropine cautiously in inferior myocardial infarction as increased heart rate may worsen ischemia 1
• For vagal bradycardia, especially in specific populations like newborns with vagal hyper-reflectivity, atropine can be particularly effective 6

Potential Complications and Pitfalls

• Atropine administration should not delay implementation of external pacing for patients with poor perfusion 1
• Excessive doses of atropine (>3 mg) may cause central anticholinergic syndrome (confusion, agitation, hallucinations) 1
• Theophylline may cause side effects including nausea, headache, insomnia, and seizures at higher levels 3
• Regular monitoring of theophylline levels is recommended when used 3
• Be prepared for paradoxical worsening of bradycardia with atropine, particularly in patients with infranodal blocks 4

Definitive Treatment

• For most symptomatic bradycardia cases that are persistent, permanent pacing remains the definitive treatment 3, 7
• Symptomatic patients with sick sinus syndrome and high second- or third-degree AV blocks require placement of permanent pacemakers 7

Monitoring and Follow-up

• Continue cardiac monitoring during and after treatment 1
• Evaluate response to therapy by monitoring heart rate, blood pressure, and resolution of symptoms 1
• The elimination half-life of atropine is more than doubled in children under two years and the elderly (>65 years old) 2