What are the management steps for a patient with bradycardia (abnormally slow heart rate)?

From the Guidelines

If a patient is bradycardic, first assess if they are symptomatic, and for symptomatic bradycardia with signs of hemodynamic instability, administer atropine 0.5 mg IV every 3-5 minutes up to a total of 3 mg, as recommended by the most recent guidelines 1. For symptomatic bradycardia, the following steps should be taken:

• Assess the patient's hemodynamic status and identify underlying causes of bradycardia
• Administer atropine 0.5-1 mg IV every 3-5 minutes as needed up to 1.5-3 mg total, as it is the first-line treatment for symptomatic bradycardia 1
• If atropine is ineffective, consider second-line treatments such as dopamine 5-20 mcg/kg/min IV or epinephrine 2-10 mcg/min IV, as recommended by the guidelines 1
• For refractory cases, consider transcutaneous pacing, and continue to identify and address underlying causes of bradycardia
• Provide oxygen if saturation is low and ensure continuous cardiac monitoring, as these are essential components of bradycardia management 1

It is essential to note that the treatment of bradycardia should be tailored to the individual patient's needs and underlying causes of bradycardia. The guidelines recommend a step-wise approach to treatment, starting with atropine and progressing to second-line treatments as needed 1. The most recent and highest quality study, which is the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, provides the basis for these recommendations 1. In addition to these guidelines, other studies have also recommended atropine as the first-line treatment for symptomatic bradycardia, with doses ranging from 0.5-1 mg IV every 3-5 minutes as needed up to 1.5-3 mg total 1. However, the 2018 ACC/AHA/HRS guideline is the most recent and highest quality study, and its recommendations should be prioritized in clinical practice 1.

From the FDA Drug Label

Atropine-induced parasympathetic inhibition may be preceded by a transient phase of stimulation, especially on the heart where small doses first slow the rate before characteristic tachycardia develops due to paralysis of vagal control Adequate doses of atropine abolish various types of reflex vagal cardiac slowing or asystole The drug also prevents or abolishes bradycardia or asystole produced by injection of choline esters, anticholinesterase agents or other parasympathomimetic drugs, and cardiac arrest produced by stimulation of the vagus.

If a patient is bradycardic, atropine (IV) can be used to prevent or abolish bradycardia.

• Atropine works by inhibiting the muscarinic actions of acetylcholine on the heart, leading to an increase in heart rate.
• Adequate doses of atropine can abolish reflex vagal cardiac slowing or asystole, and prevent or abolish bradycardia or asystole produced by other agents 2.

From the Research

Treatment Options for Bradycardia

• If a patient is bradycardic, particularly due to beta-adrenergic or calcium-channel blocker overdose, treatment options include:
  • Glucagon administration, as it has been shown to improve clinical condition in cases of symptomatic bradycardia 3
  • Beta-agonists, phosphodiesterase inhibitors, and high-dose insulin with supplemental dextrose and potassium therapy (HDIDK) may also be considered 4
• In cases of beta-blocker poisoning with symptomatic bradycardia and hypotension, high-dose glucagon is considered the first-line antidote 4
• For calcium-channel blocker poisoning with evident cardiotoxicity, first-line therapy is a combination of calcium and epinephrine, with HDIDK reserved for refractory cases 4

Important Considerations

• The cause of bradycardia should be identified, as treatment may vary depending on the underlying cause 3, 4
• Health-system pharmacists should be aware that higher than normal dosing of antidotes may be needed in cases of beta-blocker or calcium-channel blocker poisoning 4