Bradycardia is generally defined as a heart rate of < 60/min. All patients require urgent evaluation with ECG and monitoring. Patients with unstable bradycardia require immediate stabilization, initially with IV atropine, followed by transcutaneous pacing and/or IV chronotropic medications (e.g., dopamine, epinephrine), and transvenous pacing for refractory bradycardia. Treatment should also address reversible underlying , e.g., hypoxemia, acute coronary syndrome, electrolyte disturbances, and medication-induced bradycardia. Stable patients may not require immediate intervention, but often require monitoring and investigations to determine the underlying etiology and risk of progression to unstable bradycardia or sudden cardiac death. Definitive management depends on the underlying and can include permanent pacemaker implantation for patients with nonreversible bradyarrhythmias.
- Follow pulse. and check
- present: Follow .
- Stable bradycardia: Manage according to underlying etiology and symptom severity.
Patients or only mildly typically do not require acute intervention. 
Initial management of bradycardia
- Call for help.
- Establish IV access.
- Bring crash cart to bedside and attach pads.
- Begin continuous cardiac and respiratory monitoring.
- Unstable bradycardia: Begin stabilization according to the .
- Evaluate underlying rhythm.
- Identify and treat reversible supplemental O2 for hypoxemia.  , e.g.,
- Consult cardiology.
Overview of bradyarrhythmias
|Overview of common bradyarrhythmias by ECG findings|
Clinical features of unstable bradycardia 
- Acute altered mental status
- Ischemic chest pain
- Acute heart failure
- airway and breathing despite adequate
Adult unstable bradycardia algorithm 
Startand simultaneously with the following treatment:
- First-line: IV atropine
- If refractory to atropine: Start temporizing measures.
- If refractory to pharmacotherapy: Consult cardiology for .
Special situations 
- No IV access or IO access: Consider transcutaneous pacing as first-line intervention while awaiting vascular access. 
- Acute coronary syndrome
- Recent heart transplant
- Known infranodal block or a wide QRS with AV block: Consider transcutaneous pacing as first-line intervention instead of atropine. 
Spinal cord injury: Consider alternative chronotropic medications if unresponsive to atropine and inotropes.
- Aminophylline 
- OR Theophylline 
- Begin definitive therapy for specific bradyarrhythmias under specialist guidance.
- See “ .”
- See “ .”
- Identify .
- Continue treatment of the underlying .
- ABCDE survey
- IV access, continuous telemetry, and pulse oximetry
- Unstable and/or symptomatic bradycardia: Administer atropine.
- If atropine is ineffective, consider temporizing measures (tailored to the patient).
- Consult cardiology.
- Consider transvenous pacing.
- Identify and treat the underlying .
- Admit to the ICU.
Provideconcurrently for all patients.
If develop at any time, follow the .
- Conduct comprehensive clinical evaluation and obtain 12-lead ECG in all patients.
- Consider additional diagnostics on an individual basis under specialist guidance.
- Asymptomatic or only mildly symptomatic patients typically do not require acute intervention.
- Definitive management depends on the underlying rhythm.
is an .
Consult cardiology as disposition varies depending on underlying rhythm and etiology, symptom severity, and patient factors.
Temporary cardiac pacing
- Consider for conscious patients. . 
- Place the leads in the anteroposterior position.
- Set output to a level that is likely to result in capture.
- Unconscious patient: Start at 160–180 mA and decrease output if possible.
- Conscious patient: Start at a low output (e.g., 10 mA) and gradually increase until capture is seen.
- Set pacing rate to 60–80/min.
- Set a backup rate at a low level to avoid unnecessary pacing (e.g., 30/min).
- Verify ventricular capture by checking the patient's pulse manually or with pulse oximetry.
Transvenous pacing 
- Definition: The delivery of electrical impulses to stimulate cardiac contraction using an electrode placed via a central venous access site into the right ventricle; often used as a bridge to permanent pacemaker implantation
- Indications 
- Contraindications: prosthetic tricuspid valve, severe hypothermia
- Complications: Usually related to vascular access (see “Complications” in “Central venous access.”)
Acute management of reversible causes 
- Provide and/or for .
- Identify and .
- Check core temperature and provide hypothermia. for
- Identify and treat if needed.
- Screen for and treat .
- Obtain laboratory studies for metabolic causes (e.g., electrolytes, TSH) and treat urgent disturbances.
- See “ .”
- See “ .”
- Treat reversible complications, if present.
Medication-induced bradycardia 
Management depends on the indication and individual patient risk. Consult the prescribing clinician if available.
- Noncritical medication: Consider temporary hold or permanent discontinuation.
- Critical medication: Consider dosage reduction or alternative agents under specialist guidance.
Consider the following antidotes in addition to the :
- Calcium channel blocker toxicity
- Beta-blocker toxicity 
- Digoxin toxicity
Etiologies by underlying mechanism
Increased vagal tone
|Degeneration of the conducting system|