Can adrenaline (epinephrine) be used as an inotrope in cases of bradycardia?

Can Adrenaline Be Used as an Inotrope in Bradycardia?

Yes, adrenaline (epinephrine) can and should be used as an inotrope in bradycardia when first-line atropine therapy fails or when the patient has hemodynamic compromise requiring both chronotropic and inotropic support. 1, 2

Treatment Algorithm for Symptomatic Bradycardia

First-Line Therapy

• Administer atropine 0.5-1 mg IV as initial treatment for symptomatic bradycardia 1, 2
• Repeat atropine every 3-5 minutes up to a maximum total dose of 3 mg 1, 2
• Avoid doses <0.5 mg as they may paradoxically worsen bradycardia 2

Second-Line Therapy: When Atropine Fails

Epinephrine is specifically recommended when atropine and transcutaneous pacing fail or pacing is unavailable 1:

• Starting dose: 2-10 mcg/min IV infusion (or 0.1-0.5 mcg/kg/min in a 70-kg adult = 7-35 mcg/min) 1, 2
• Titrate to hemodynamic response and heart rate 1, 2
• Epinephrine provides both chronotropic effects (increases heart rate) and inotropic effects (increases contractility) 1

Alternative Second-Line Agent: Dopamine

• Starting dose: 5-10 mcg/kg/min IV infusion 1, 2
• Particularly useful when hypotension accompanies symptomatic bradycardia 1
• Titrate by 2-5 mcg/kg/min every 2-5 minutes based on response 2
• Maximum dose: 20 mcg/kg/min (higher doses cause excessive vasoconstriction and arrhythmias) 2

Clinical Context: When to Choose Epinephrine Over Dopamine

Epinephrine is preferred in:

• Severe hypotension (systolic BP <70 mmHg) with bradycardia 1
• Exsanguinated patients with absolute bradycardia 3
• Heart transplant patients (where atropine may cause paradoxical high-degree AV block) 1, 2
• When both strong chronotropic and inotropic support are urgently needed 1

Dopamine may be preferred when:

• More titratable, dose-dependent effects are desired 2
• The patient requires both chronotropy and blood pressure support but less aggressive vasoconstriction than epinephrine provides 2

Critical Warnings and Pitfalls

Location of Heart Block Matters

• Atropine (and by extension, the need for epinephrine) is likely effective for sinus bradycardia, AV nodal block, and sinus arrest 2
• Atropine is unlikely effective for Type II second-degree AV block or third-degree AV block with wide QRS (infranodal block) 2, 4
• In infranodal blocks, atropine may paradoxically worsen bradycardia or cause ventricular standstill 4

Ischemic Heart Disease Considerations

• Use with extreme caution in acute coronary ischemia or myocardial infarction 1, 2
• Increasing heart rate may worsen ischemia or increase infarct size 2
• Epinephrine increases myocardial oxygen demand, potentially creating supply-demand mismatch 1

Cardiogenic Shock Context

• In cardiogenic shock, epinephrine is NOT recommended as a first-line inotrope or vasopressor and should be restricted to cardiac arrest scenarios 1
• For cardiogenic shock with bradycardia, dopamine may be considered, but norepinephrine is preferred if tachycardia is already present 1

Rare but Serious Adverse Effect

• Epinephrine can cause stress cardiomyopathy (takotsubo-like presentation) 5
• This is dose and route-dependent, with management being supportive and outcomes generally good 5

Practical Implementation

Administration Route

• Central line preferred for all catecholamines to avoid tissue necrosis from extravasation 1
• If extravasation occurs, infiltrate 5-10 mg phentolamine diluted in 10-15 mL saline immediately 1
• Do not mix with sodium bicarbonate or alkaline solutions (inactivates adrenergic agents) 1

Concurrent Measures

• Do not delay transcutaneous pacing while administering medications in unstable patients 2
• Maintain cardiac monitoring, establish IV access, obtain 12-lead ECG 2
• Monitor for resolution of symptoms, improvement in blood pressure, and adequate heart rate response 2

Special Population: Heart Transplant Patients

• Avoid atropine in heart transplant patients without autonomic reinnervation 1, 2
• Atropine may cause paradoxical high-degree AV block or sinus arrest in 20% of transplant patients 1
• Epinephrine is the preferred agent in this population 2