What is the treatment plan for an inpatient with bradycardia (abnormally slow heart rate)?

Treatment Plan for Inpatient Bradycardia

The first-line treatment for symptomatic bradycardia in the inpatient setting is atropine 0.5-1 mg IV, which can be repeated every 3-5 minutes to a maximum dose of 3 mg. 1 This approach is recommended by the American Heart Association for patients with bradycardia associated with symptoms or hemodynamic compromise.

Initial Assessment and Management

1. Define clinical significance:

   • Bradycardia is defined as heart rate <60 beats/minute, but clinically significant bradycardia typically presents with heart rate <50 beats/minute 2
   • Assess for symptoms: altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or other signs of shock 2

2. Immediate stabilization measures:

   • Maintain patent airway
   • Provide oxygen if hypoxemic
   • Establish cardiac monitoring
   • Monitor blood pressure and oxygen saturation
   • Establish IV access
   • Obtain 12-lead ECG (if available) 2

3. Identify and treat underlying causes:

   • Medications (beta-blockers, calcium channel blockers, digoxin, antiarrhythmics)
   • Electrolyte abnormalities (hyperkalemia, hypokalemia)
   • Hypothyroidism
   • Increased intracranial pressure
   • Acute myocardial infarction
   • Hypoxemia
   • Hypothermia 2

Pharmacologic Treatment Algorithm

First-line therapy:

• Atropine: 0.5-1 mg IV every 3-5 minutes (maximum total dose: 3 mg) 2, 1
  • Mechanism: Competitive antagonism of acetylcholine at muscarinic receptors 3
  • Caution: May be ineffective in type II second-degree AV block, third-degree AV block with wide QRS, and post-heart transplant patients 1

If inadequate response to atropine:

1. Beta-adrenergic agonists (choose one):

   • Dopamine: 5-20 mcg/kg/min IV infusion 2
   • Epinephrine: 2-10 mcg/min IV infusion 2
   • Isoproterenol: 20-60 mcg IV bolus followed by 10-20 mcg, or infusion of 1-20 mcg/min 2
   • Dobutamine: For patients with low likelihood of coronary ischemia 2

2. For specific causes:

   • Calcium channel blocker overdose: 10% calcium chloride 1-2 g IV every 10-20 min or infusion 2
   • Beta-blocker overdose: Glucagon 3-10 mg IV with infusion of 3-5 mg/h 2
   • Both beta-blocker or calcium channel blocker overdose: High-dose insulin therapy (1 unit/kg IV bolus followed by 0.5 units/kg/h infusion) 2
   • Digoxin toxicity: Digoxin-specific antibody fragments (dosage based on amount ingested) 2
   • Post-heart transplant or spinal cord injury: Aminophylline 6 mg/kg IV over 20-30 min 2

Pacing Options

If pharmacologic therapy fails to improve symptoms or hemodynamic status:

1. Transcutaneous pacing (TCP):

   • Immediate temporizing measure
   • Painful in conscious patients 1

2. Transvenous pacing:

   • More reliable capture than transcutaneous pacing
   • Indicated when patient does not respond to drugs or TCP 1
   • Consider early if high-degree AV block is present 1

3. Permanent pacemaker consideration:

   • For persistent symptomatic bradycardia
   • Early implantation (≤2 days) should be considered to reduce the need for temporary transvenous pacing and shorten hospital stay 4

Monitoring and Follow-up

• Continuous cardiac monitoring until stable
• Regular assessment of vital signs and symptoms
• Monitor for adverse effects of medications:
  • Atropine: tachycardia, urinary retention, confusion
  • Beta-agonists: arrhythmias, ischemia
  • Calcium: hypercalcemia
  • Glucagon: nausea, vomiting

Common Pitfalls to Avoid

1. Delaying treatment in symptomatic patients
2. Using atropine in patients with infranodal blocks (may worsen block)
3. Failing to recognize and address drug-induced causes
4. Overlooking metabolic causes (thyroid, electrolytes)
5. Excessive atropine dosing (>1.0 mg initial dose or >2.5 mg cumulative dose over 2.5 hours) which may lead to ventricular arrhythmias 5
6. Unnecessary treatment of asymptomatic bradycardia 6

Remember that approximately half of patients with hemodynamically unstable bradycardia will have either a partial or complete response to atropine therapy, with adverse responses being uncommon 7. Patients with sinus bradycardia tend to respond better to atropine than those with AV block 7.