There are three medications used in the bradycardia algorithm: atropine, epinephrine, and dopamine. Read about each drug and its use within the bradycardia algorithm below.
When symptomatic bradycardia occurs, the primary objective is to identify and treat the cause of the problem. Medications are indicated if symptomatic bradycardia cannot be corrected by treating an underlying cause or if the cause cannot be determined.
2020 AHA UpdateThe single-dose administration of atropine was increased from 0.5 mg to 1 mg. Now give 1 mg for the first dose and then repeat every 3-5 minutes at the 1 mg dose. Also, the dopamine infusion rate for chemical pacing was changed to 5-20 mcg/kg/min.
The previous rate from the 2015 guidelines was 2-20 mcg/kg/min.
Atropine is the first line medication for the treatment of bradycardia. The administration of atropine typically causes an increase in heart rate. This increase in the heart rate occurs when atropine blocks the effects of the vagus nerve on the heart. When the vagus nerve is blocked, the SA node increases its rate of electrical discharge and this, in turn, results in the increased HR.
Use atropine cautiously in the presence of myocardial ischemia and hypoxia because it increases oxygen demand on the heart and can worsen ischemia.
The dosing for Atropine is 1 mg IV every 3-5 minutes as needed, and the maximum total dosage for administration is 3 mg.
Atropine should be avoided with bradycardia caused by hypothermia and, in most cases, it will not be effective for Mobitz type II/Second-degree block type 2 or complete heart block.
You may have read that atropine is not effective for Mobitz II (2nd-degree block type II) and complete heart block (3rd-degree block)
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Epinephrine and Dopamine
Epinephrine and dopamine are second-line drugs for symptomatic bradycardia. They are both used as infusions in the bradycardia algorithm if atropine is ineffective.
ACLS guidelines state that if bradycardia is unresponsive to atropine, an equally effective alternative to transcutaneous pacing is the use of an IV infusion of the beta-adrenergic agonists (dopamine or epinephrine).
IV infusion for bradycardia:
- 1mg epinephrine is mixed with 500ml of NS or D5W. The infusion should run at 2-10 mcg/min and titrate to the patient’s response.
- Dopamine 400 mg is mixed with 250 ml NS. Begin the dopamine infusion at 5 to 20 mcg/kg/min and titrate to the patient’s response.
The goal of therapy is to improve the patient’s clinical status rather than target an exact heart rate.
Prior to the use of ACLS drugs in the treatment of symptomatic bradycardia, contributing factors of the bradycardia should be explored then ruled out or corrected.