What medication is used to raise heart rate (hr) in cases of bradycardia?

Medications for Raising Heart Rate in Bradycardia

Atropine is the first-line pharmacological treatment for symptomatic bradycardia, administered at doses of 0.5-1 mg IV, which may be repeated every 3-5 minutes to a maximum dose of 3 mg. 1, 2

First-Line Treatment: Atropine

• Atropine is a parasympatholytic drug that blocks muscarinic acetylcholine receptors, facilitating sinoatrial conduction and increasing sinus node automaticity 1, 3
• For symptomatic bradycardia or hemodynamic compromise, atropine is reasonable to increase sinus rate (Class IIa recommendation) 1
• Typical dosing: 0.5-1 mg IV, may be repeated every 3-5 minutes to a maximum dose of 3 mg 1, 2
• Atropine can significantly increase both heart rate (from 46±14 to 79±12/min) and systolic blood pressure in patients with bradycardia-hypotension syndrome 4

Second-Line Treatments (If Atropine Is Ineffective)

Dopamine

• Recommended dose: 5-20 mcg/kg/min IV, starting at 5 mcg/kg/min and increasing by 5 mcg/kg/min every 2 minutes 1, 2
• Has mixed alpha-adrenergic, beta-adrenergic, and dopaminergic effects that depend on dosage 1
• At 5-20 mcg/kg/min, enhanced chronotropy and inotropy predominate 1
• Caution: Doses >20 mcg/kg/min may result in excessive vasoconstriction and arrhythmias 1, 2

Isoproterenol

• Recommended dose: 20-60 mcg IV bolus followed by doses of 10-20 mcg, or infusion of 1-20 mcg/min based on heart rate response 1
• Nonselective beta agonist with both chronotropic and inotropic effects 1
• May be considered in patients with SND at low likelihood of coronary ischemia (Class IIb recommendation) 1
• Monitor for potential development of ischemic chest pain 1

Epinephrine (Noradrenaline)

• Recommended dose: 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to desired effect 1, 2
• Has strong alpha-adrenergic and beta-adrenergic stimulatory effects 1, 2
• May be considered in patients with SND at low likelihood of coronary ischemia (Class IIb recommendation) 1

Dobutamine

• May be considered in patients with SND associated with symptoms or hemodynamic compromise who are at low likelihood of coronary ischemia (Class IIb recommendation) 1

Special Clinical Scenarios

Post-Heart Transplant Bradycardia

• Atropine should NOT be used in patients who have undergone heart transplant without evidence for autonomic reinnervation (Class III: Harm) 1
• Alternative treatments include:
  • Aminophylline: 6 mg/kg in 100-200 mL of IV fluid over 20-30 min 1
  • Theophylline: 300 mg IV, followed by oral dose of 5-10 mg/kg/d titrated to effect 1

Bradycardia Due to Beta-Blocker or Calcium Channel Blocker Overdose

• Glucagon: 3-10 mg IV with infusion of 3-5 mg/h 1
• High-dose insulin therapy: IV bolus of 1 unit/kg followed by an infusion of 0.5 units/kg/h 1
• For calcium channel blocker overdose specifically:
  • 10% calcium chloride: 1-2 g IV every 10-20 min or infusion of 0.2-0.4 mL/kg/h 1
  • 10% calcium gluconate: 3-6 g IV every 10-20 min or infusion at 0.6-1.2 mL/kg/h 1

Treatment Algorithm for Bradycardia

1. Evaluate and treat reversible causes of bradycardia (Class I recommendation) 1, 2

   • Common reversible causes include medications (beta blockers, calcium channel blockers, digoxin), electrolyte abnormalities, hypothyroidism, increased intracranial pressure, and sleep apnea 1

2. For symptomatic bradycardia or hemodynamic compromise:

   • Administer atropine 0.5-1 mg IV (may repeat every 3-5 min to maximum 3 mg) 1, 5

3. If bradycardia persists despite atropine:

   • Initiate dopamine 5 mcg/kg/min IV, increasing by 5 mcg/kg/min every 2 minutes to maximum 20 mcg/kg/min 1, 2
   • OR consider isoproterenol, epinephrine, or dobutamine if dopamine is ineffective or contraindicated 1, 2

4. If pharmacologic therapy fails:

   • Consider transcutaneous pacing as a bridge to definitive treatment 5, 6
   • The only definitive therapy for persistent bradycardia is placement of a permanent pacemaker 5, 6

Important Caveats

• Low doses of atropine (less than 0.5 mg) may paradoxically worsen bradycardia due to central vagal stimulation 7
• Atropine dose should be carefully calculated based on weight (0.008 mg/kg represents a safe initial dose) 8
• Continuous cardiac monitoring is essential for all patients requiring chronotropic medications 2
• In acute myocardial infarction, atropine may reduce ventricular premature complexes associated with bradycardia 4
• The elimination half-life of atropine is more than doubled in children under two years and the elderly (>65 years) 3