From the Guidelines
The management algorithm for bradycardia involves assessing the patient for signs of hemodynamic instability and administering atropine 0.5 mg IV, which can be repeated every 3-5 minutes to a maximum dose of 3 mg, as the first-line treatment for acute symptomatic bradycardia, as recommended by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Assessment and Initial Management
The first step in managing bradycardia is to assess the patient for signs of hemodynamic instability, such as hypotension, altered mental status, chest pain, or heart failure. If the patient is unstable, immediate intervention is necessary.
Pharmacological Management
The following medications can be used to manage bradycardia:
- Atropine: 0.5-1 mg IV, which can be repeated every 3-5 minutes to a maximum dose of 3 mg 1
- Dopamine: 5 to 20 mcg/kg/min IV, starting at 5 mcg/kg/min and increasing by 5 mcg/kg/min every 2 min 1
- Isoproterenol: 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
- Epinephrine: 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to desired effect 1
Temporary Pacing
Temporary pacing can be used to acutely treat bradycardia causing hemodynamically significant instability, such as prolonged and symptomatic pauses, life-threatening ventricular arrhythmias mediated by bradycardia, or severe symptomatic bradycardia attributable to a reversible cause with the goal to avoid PPM implantation 1.
Permanent Pacemaker Implantation
For patients with recurrent symptomatic bradycardia, permanent pacemaker implantation should be considered as definitive therapy, especially for high-grade AV blocks, symptomatic sinus node dysfunction, or other non-reversible causes of bradycardia.
Key Considerations
- Atropine may be ineffective for infranodal blocks or denervated hearts (e.g., post-cardiac transplant) 1.
- Temporary pacing can be implemented transcutaneously, via a transesophageal approach, or by insertion of a transvenous pacing electrode or pulmonary-arterial pacing catheter 1.
From the FDA Drug Label
Atropine Sulfate Injection, USP in clinical doses counteracts the peripheral dilatation and abrupt decrease in blood pressure produced by choline esters 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.
The management algorithm for bradycardia may include the use of atropine as it can counteract vagal cardiac slowing and abolish bradycardia or asystole.
- Atropine can be used to prevent or abolish bradycardia produced by various factors, including choline esters and parasympathomimetic drugs.
- The use of atropine may help increase the heart rate in patients with bradycardia, especially when vagal activity is an etiologic factor 2.
From the Research
Management Algorithm for Bradycardia
The management of bradycardia involves a step-wise approach, with the initial step being the assessment of the patient's hemodynamic stability.
- If the patient is unstable, the first-line treatment is often intravenous (IV) atropine 3, 4.
- If atropine is unsuccessful, the next steps may include IV adrenaline or isoprenaline and transcutaneous pacing 3, 5.
- Transcutaneous cardiac pacing (TCP) has been shown to be effective in patients with atropine-resistant unstable bradycardia 6.
- The use of TCP in the prehospital setting may also be beneficial, particularly in patients with a palpable pulse upon paramedic arrival 7.
Key Considerations
- The location of the heart block may affect the response to atropine, with patients having atrioventricular blocks at the level of the His-Purkinje fibres being at increased risk of adverse events 3.
- Paramedics should be prepared to manage unexpected adverse events secondary to atropine administration in patients with heart block 3.
- The efficacy of TCP in unstable bradycardia patients has been demonstrated in several studies, with significant improvements in vital signs and electrocardiography 6, 7.