What is the initial workup and management for a patient presenting with bradycardia?

Initial Workup and Management of Bradycardia

The initial workup for bradycardia should include a 12-lead ECG, comprehensive history, physical examination, and cardiac monitoring to establish correlation between symptoms and rhythm, followed by targeted laboratory testing and appropriate management based on symptom severity. 1

Initial Assessment

• Evaluate if heart rate is appropriate for clinical condition, typically defined as less than 50 beats per minute when symptomatic 1, 2
• Assess for signs and symptoms of poor perfusion, including altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or shock 1, 2
• Maintain patent airway and assist breathing as necessary 2
• Provide supplementary oxygen if hypoxemia is present 2
• Attach cardiac monitor to identify rhythm, monitor blood pressure, and measure oxygen saturation 2
• Establish IV access for medication administration 2
• Obtain 12-lead ECG to document rhythm, rate, conduction abnormalities, and screen for structural heart disease 1, 2

Diagnostic Workup

• Cardiac rhythm monitoring should be selected based on frequency and nature of symptoms:
  • Holter monitor (24-48 hours)
  • Event monitor (up to 30 days)
  • Implantable cardiac monitor (for infrequent symptoms) 1
• Laboratory testing directed toward suspected specific diagnoses:
  • Thyroid function tests
  • Electrolyte panel (particularly potassium levels)
  • Lyme titer in endemic areas
  • Drug levels (digoxin, beta-blockers, calcium channel blockers) 1

Identify and Treat Reversible Causes

• Medications: beta-blockers, calcium channel blockers, digoxin, antiarrhythmic drugs 2
• Electrolyte abnormalities: hyperkalemia, hypokalemia 2
• Hypothyroidism 2
• Acute myocardial ischemia or infarction 2
• Increased intracranial pressure 1, 2
• Hypothermia 1, 2
• Infections (particularly Lyme disease) 1, 2
• Sleep apnea 2

Management Algorithm for Symptomatic Bradycardia

For Unstable Patients (with signs of poor perfusion)

1. First-line therapy: Atropine

   • Dose: 0.5 mg IV every 3-5 minutes to a maximum total dose of 3 mg 1, 2, 3
   • Consider atropine a temporizing measure while awaiting more definitive treatment 2
   • For patients with coronary artery disease, limit the total dose to 0.03-0.04 mg/kg 3

2. If atropine is ineffective or contraindicated:

   • IV infusion of β-adrenergic agonists:
     • Dopamine (especially if bradycardia is associated with hypotension) 2
     • Epinephrine 1, 2

3. If pharmacologic therapy fails:

   • Initiate transcutaneous pacing for unstable patients 1, 2
   • Prepare for transvenous pacing if temporary measures are ineffective 2
   • Consider expert consultation for complex cases 2

For Stable Patients with Symptomatic Bradycardia

• Identify and treat reversible causes 1
• Monitor closely for deterioration 4
• Consider permanent pacing for chronic symptomatic bradycardia, particularly if caused by necessary medications with no alternatives 1, 2

Special Considerations

• Weekend hospital admissions may be associated with delayed permanent pacemaker implantation, increased use of temporary transvenous pacing, and prolonged hospital stays 5
• Temporary transvenous pacing is associated with higher rates of adverse events compared to early or delayed permanent pacemaker implantation 5
• Treatment should rarely be prescribed solely on the basis of a heart rate lower than an arbitrary cutoff 6
• Even marked bradycardia can be physiologic in some patients, and in the presence of impaired ventricular function may offer important compensatory hemodynamic effects 7

Common Pitfalls to Avoid

• Failing to identify medication-induced bradycardia, which is a common reversible cause 2
• Overuse of permanent pacemakers in mildly symptomatic patients with favorable prognosis 7
• Delaying ECG or therapy in unstable patients 2
• Neglecting to consider bradycardia as a manifestation of serious underlying conditions such as myocardial infarction or increased intracranial pressure 1, 2
• Using atropine in patients with suspected cardiac transplantation (denervated hearts won't respond) 8