What is the treatment for symptomatic bradycardia?

Treatment of Symptomatic Bradycardia

For symptomatic bradycardia, the first-line treatment is intravenous atropine 0.5-1 mg, which can be repeated every 3-5 minutes 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
• Identify and treat underlying causes of bradycardia 1

Treatment Algorithm

First-Line Treatment

• Administer atropine 0.5-1 mg IV for symptomatic bradycardia 1, 2
• Repeat atropine every 3-5 minutes as needed up to a maximum total dose of 3 mg 1
• Important caution: Doses of atropine <0.5 mg may paradoxically worsen bradycardia due to central vagal stimulation and should be avoided 3, 1

If Bradycardia Persists Despite Atropine

• Initiate IV infusion of β-adrenergic agonists 1:
  • Dopamine (2-10 μg/kg/min) 3, 1
  • Epinephrine (2-10 μg/min) 3, 1
  • Isoproterenol (for AV block with low likelihood of coronary ischemia) 3, 1
• 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, 4

Special Considerations

Type of AV Block

• Atropine is likely to be effective in sinus bradycardia, conduction block at the AV node level, or sinus arrest 1
• Atropine may be ineffective in type II second-degree or third-degree AV block with new wide-QRS complex (infranodal block) 1, 5
• Patients with heart blocks at the level of the His-Purkinje fibers (infranodal) may experience paradoxical worsening of bradycardia with atropine administration 5

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 or increase infarction size 1
• For BRASH syndrome (Bradycardia, Renal failure, AV nodal blockers, Shock, and Hyperkalemia), atropine may be ineffective and isoproterenol may be needed 6

Oral Medication Options

• Theophylline is recommended as the primary oral medication for treating symptomatic bradycardia, particularly in patients with sinus node dysfunction 3
• Oral theophylline is particularly useful in specific scenarios such as after inferior myocardial infarction, in cardiac transplant patients, and in patients with spinal cord injury 3, 7
• Regular monitoring of theophylline levels is recommended to maintain therapeutic effect while avoiding toxicity 3

Permanent Pacing Considerations

• For most symptomatic bradycardia cases, permanent pacing remains the definitive treatment when bradycardia is persistent and symptomatic 3, 4
• Approximately 50% of patients presenting with compromising bradycardia may require permanent pacemaker implantation 4

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, including confusion, agitation, and hallucinations 1
• Atropine works by competitively antagonizing muscarinic actions of acetylcholine, which may not be effective in all types of bradycardia 2
• Be prepared for unexpected adverse events following atropine administration, especially in patients with heart block 5