Bradycardia

1Unstable?

Unstable Criteria

• Assess for hypotension or shock.
• Assess for hypoperfusion.
• Assess for acute heart failure.
• Assess for acute altered mental status.
• Assess for ischemic chest discomfort.

2Level Of Block?

Sinus Rhythm / Sinus Node Dysfunction — SA Node

• Look for P waves before each QRS.
• The bradycardia may be physiologic or drug-related.
• Consider sinus node dysfunction.
• If the patient is unstable, treat without delay.

First-Degree Or Second-Degree (Wenckebach) AV Block — AV Node

• The block is often nodal; assess the patient’s symptoms.
• The QRS may be narrow.
• Atropine may improve nodal block.

Second-Degree (Mobitz II) Or Third-Degree AV Block — Infranodal Risk

• QRS width alone does not locate the block.
• Atropine is less reliable if the block is infranodal.
• Prepare pacing and seek expert input.

3Treatment: Bradycardia

Initial Support

• Support ABCs.
• Cardiac monitor / pulse oximetry.
• Obtain IV access.
• Obtain a 12-lead ECG if it does not delay treatment.

Bradycardia (Unstable)

Atropine

• Give atropine 1 mg IV every 3–5 minutes, to a maximum total dose of 3 mg.

If Atropine Is Ineffective

• Use transcutaneous pacing and/or an IV infusion.
• Infusion options are epinephrine 2–10 mcg/min IV or dopamine 5–20 mcg/kg/min IV.

Expert Input

• Seek expert input and consider transvenous pacing.

2025 AHA adult bradycardia algorithm · AHA recommendations and evidence

4Treatment: Underlying Cause

Hypoxia

• Correct hypoxemia / respiratory failure.
• Oxygen and ventilatory support as needed.

Drugs / Overdose

Beta-Blocker Toxicity

• For beta-blocker–associated shock, use vasopressors; use high-dose insulin if the shock is refractory.

Calcium Channel Blocker Toxicity

• For calcium channel blocker–associated shock, use high-dose insulin and vasopressors, with IV calcium.

Digoxin Toxicity

• Use digoxin immune Fab for severe toxicity.

AHA guidance: life-threatening poisoning

Electrolytes — Hyperkalemia

• Give IV calcium for ECG changes.
• Give IV insulin and glucose according to protocol.
• Add nebulized albuterol.
• Monitor glucose and potassium.
• Treat contributing causes.
• Obtain urgent renal and critical care input.
• Use dialysis for severe or refractory cases.

Ischemia

• Evaluate for acute coronary syndrome (ACS) and reperfuse as indicated.