Management of Symptomatic Bradycardia
The first-line treatment for symptomatic bradycardia is intravenous atropine 0.5 to 1 mg, repeated 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, such as altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or other signs of shock 1
- Maintain patent airway and assist breathing as necessary 1
- Provide supplemental oxygen if the patient is hypoxemic or shows signs of increased work of breathing 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 (without delaying therapy) 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
- Repeat every 3-5 minutes as needed up to a maximum total dose of 3 mg 1
- Doses of atropine <0.5 mg may paradoxically result in further slowing of heart rate and should be avoided 1
If Bradycardia Persists Despite Atropine
If bradycardia is unresponsive to atropine or atropine is likely to be ineffective:
Initiate IV infusion of β-adrenergic agonists 1:
Consider transcutaneous pacing (TCP) in unstable patients who do not respond to atropine 1
Prepare for transvenous pacing if the patient does not respond to drugs or TCP 1
Special Considerations
Type of AV Block
- Atropine is likely to be effective in sinus bradycardia, conduction block at the level of the AV node, or sinus arrest 1
- Atropine may be ineffective in type II second-degree or third-degree AV block with new wide-QRS complex where the block is likely in non-nodal tissue (bundle of His or more distal conduction system) 1
Specific Clinical Scenarios
- Heart transplant patients: Avoid atropine in patients who have undergone cardiac transplantation without evidence of autonomic reinnervation, as it may cause paradoxical high-degree AV block 1, 2
- Inferior myocardial infarction: Use atropine cautiously as increased heart rate may worsen ischemia or increase infarction size 1
- Spinal cord injury: Consider aminophylline (100-200 mg slow IV injection) if bradycardia is unresponsive to atropine 3
- BRASH syndrome (Bradycardia, Renal failure, AV nodal blockade, Shock, Hyperkalemia): Management extends beyond atropine to include correction of hyperkalemia, hemodynamic support, and possibly renal replacement therapy 4
Potential Complications and Pitfalls
- Atropine administration should not delay implementation of external pacing for patients with poor perfusion 1
- Paradoxical worsening of bradycardia can occur after atropine administration, particularly in patients with infranodal heart blocks 2
- Excessive doses of atropine (>3 mg) may cause central anticholinergic syndrome, including confusion, agitation, and hallucinations 5
- Elderly patients and children under 2 years have prolonged elimination half-life of atropine (more than doubled), requiring careful dosing 5
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
- Consider cardiology consultation for patients with recurrent symptomatic bradycardia to evaluate the need for permanent pacing 6
- For patients with bradycardia-tachycardia syndrome, address both components of the condition as bradycardia can facilitate the emergence of atrial fibrillation 7