Treatment for 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, 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 and monitor vital signs 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 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, 1
If Bradycardia Persists Despite Atropine
- Initiate IV infusion of β-adrenergic agonists: 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
Oral Medication Option
- Theophylline may be considered as an oral medication for chronic 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, 4, 5
Special Considerations
Type of AV Block
- Atropine is likely 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, 6
- Paradoxical worsening of bradycardia may occur with atropine in patients with His-Purkinje (infranodal) blocks 6
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 most persistent symptomatic bradycardia cases, permanent pacing remains the definitive treatment 3, 7
- In patients with tachy-brady syndrome and symptoms attributable to bradycardia, permanent pacing is reasonable 3
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
- Atropine may not be effective in all types of bradycardia, particularly in infranodal blocks 6
- Approximately 20% of patients with compromising bradycardia may require temporary emergency pacing for initial stabilization 7
- In cases resistant to standard treatment, aminophylline or theophylline may be considered as alternative agents, particularly in spinal cord injury-related bradycardia 4, 5