Is dopamine more beneficial than epinephrine (adrenaline) for treating bradycardia?

From the Guidelines

Epinephrine is generally more beneficial than dopamine for treating bradycardia. For acute symptomatic bradycardia, epinephrine is typically administered at 2-10 mcg/min IV infusion, which can be titrated based on heart rate response 1. Epinephrine works rapidly by stimulating both alpha and beta adrenergic receptors, with beta-1 effects increasing heart rate and contractility. Dopamine, while also effective, typically requires higher doses (5-20 mcg/kg/min) to achieve chronotropic effects and has a less predictable response profile 1. Epinephrine's stronger beta-1 activity makes it particularly effective for increasing heart rate in emergency situations. Additionally, epinephrine maintains better cerebral and coronary perfusion during bradycardic episodes. For patients with profound bradycardia causing hemodynamic compromise, epinephrine should be considered while preparing for temporary pacing if the bradycardia is refractory to medical management. However, the choice between these medications should account for the specific clinical scenario, underlying cause of bradycardia, and patient comorbidities.

Some key points to consider when choosing between epinephrine and dopamine for bradycardia include:

• The dose of epinephrine is typically lower than that of dopamine, with epinephrine administered at 2-10 mcg/min IV infusion and dopamine at 5-20 mcg/kg/min IV infusion 1.
• Epinephrine has a more rapid onset of action and a more predictable response profile compared to dopamine 1.
• The specific clinical scenario, underlying cause of bradycardia, and patient comorbidities should be taken into account when choosing between epinephrine and dopamine 1.

It's also important to note that atropine is often the first-line treatment for symptomatic bradycardia, and epinephrine or dopamine may be considered as second-line therapy if atropine is not effective 1. Overall, the choice between epinephrine and dopamine for treating bradycardia should be based on the individual patient's needs and the specific clinical scenario.

From the FDA Drug Label

Dopamine exhibits an inotropic action on the myocardium, resulting in increased cardiac output. Increased output has been associated with unchanged or decreased systemic vascular resistance (SVR). Dopamine's direct inotropic effect on the myocardium which increases cardiac output at low or moderate doses is related to a favorable prognosis

The FDA drug label does not answer the question about the benefit of dopamine vs epinephrine for bradycardia.

From the Research

Comparison of Dopamine and Epinephrine for Bradycardia

• Dopamine and epinephrine are both used to treat bradycardia, but their effects on the heart differ 2.
• Dopamine increases automaticity in Purkinje fibers and has a biphasic effect on action-potential duration, which can lead to atrial and ventricular tachyarrhythmias in animals 2.
• In humans, dopamine has been shown to cause dose-related sinus tachycardia, with few reports of clinically significant ventricular arrhythmias 2.
• Epinephrine, on the other hand, shortens sinus cycle length, increases atrial and ventricular automaticity, promotes atrioventricular nodal conduction, and decreases ventricular effective refractory period (ERP), which can lead to ventricular fibrillation and decrease the ventricular fibrillation threshold (VFT) in ex vivo models and intact animals 2.
• In humans, epinephrine may cause dose-related sinus tachycardia, supraventricular arrhythmias, or ventricular arrhythmias 2.

Benefits of Dopamine over Epinephrine

• Dopamine may be more beneficial than epinephrine for treating bradycardia due to its ability to facilitate reflex bradycardia, which is mediated by dopaminergic synapses within the caudate-putamen complex 3, 4.
• Activation of dopaminergic receptors within the caudate-putamen complex has been shown to enhance reflex bradycardia in rats, while inhibition of these receptors reduces reflex bradycardia 3, 4.
• However, there is limited evidence directly comparing the effectiveness of dopamine and epinephrine for treating bradycardia in humans.

Other Treatment Options

• Other treatment options for bradycardia include atropine, pacing, and aminophylline 5, 6.
• Aminophylline has been used to treat severe symptomatic bradycardia resistant to atropine, and may work by increasing cyclic adenosine monophosphate (cAMP) and activating the sympathoadrenal system 6.
• Pacing, including transcutaneous pacing, may also be effective for treating unstable bradycardia, but may require a larger sample size to determine its effectiveness compared to dopamine 5.