Atrial fibrillation with slow ventricular response
AV block identification
AV block patterns
First degree AV block (I44.0)
Prolonged PR with 1 to 1 conduction
Often benign if asymptomatic
Second degree AV block type I (Wenckebach) (I44.1)
Progressive PR prolongation
Dropped QRS
Second degree AV block type II (I44.1)
Fixed PR
Dropped QRS
Higher risk of progression
Third degree AV block (I44.2)
AV dissociation
Escape rhythm
High risk ECG features
ECG danger features
Wide QRS escape rhythm
Ventricular pause 3 seconds or longer
Ischemic changes
Hyperkalemia pattern features
Assessment
Problem representation
Syndrome summary
Symptomatic bradycardia with pulse
Asymptomatic bradycardia
Bradycardia with syncope
Severity and risk stratification
Severity features
Hemodynamic instability
End organ hypoperfusion
Requirement for pacing
High risk conduction disease features
Mobitz type II
Complete heart block
Wide QRS escape rhythm
Reversible causes framework
Reversible causes
Ischemia
Hypoxia
Electrolyte abnormality
Hypothermia
Drug toxicity
Endocrine disorder
Working diagnoses
Working diagnosis options
Sinus bradycardia (R00.1)
Sick sinus syndrome (I49.5)
Second degree AV block (I44.1)
Complete AV block (I44.2)
Plan
First 5 minutes workflow
Immediate stabilization sequence
Airway patency and oxygen if hypoxemic
Cardiac monitor
Defibrillator pads for pacing readiness
IV access
At least one large bore peripheral line
Two lines if unstable or toxin concern
12 lead ECG early
Point of care glucose
Reversible causes targeted treatment initiation
Algorithm based treatment
Symptomatic bradycardia treatment pathway
Atropine IV
Dose 1 mg bolus
Repeat every 3 to 5 minutes
Maximum total 3 mg
If atropine ineffective
Transcutaneous pacing
Analgesia and sedation if awake and time allows
Mechanical capture confirmation
Epinephrine infusion
Dose 2 to 10 mcg per minute
Titrate to perfusion targets
Dopamine infusion
Dose 5 to 20 mcg per kg per minute
Titrate to perfusion targets
Expert consultation
Cardiology
Electrophysiology when available
Transvenous pacing
Persistent instability despite above
High grade AV block
Reversible cause directed therapies
Etiology specific interventions
Hyperkalemia management when suspected
Calcium salt for ECG changes
Insulin with dextrose
Beta agonist therapy
Dialysis pathway when indicated
Beta blocker toxicity pathway
Glucagon per local protocol dependent
High dose insulin euglycemia therapy per local protocol dependent
Lipid emulsion per local protocol dependent
Calcium channel blocker toxicity pathway
Calcium salts
High dose insulin euglycemia therapy per local protocol dependent
Vasopressor support per response
Digoxin toxicity pathway
Digoxin immune Fab per local protocol dependent
Avoid calcium in severe digoxin toxicity concern
Hypothermia pathway
Active rewarming
Gentle handling
Monitoring and reassessment loop
Reassessment cadence
Vitals every 5 minutes in unstable patient
Mental status trend
Perfusion markers
Repeat ECG after each major intervention
Infusion titration every 5 to 10 minutes to effect
Disposition
ICU criteria
ICU level of care indications
Transvenous pacing required
Ongoing vasopressor or chronotrope infusion
Persistent hypotension
High grade AV block with instability
Inpatient admission criteria
Admission indications
Symptomatic bradycardia requiring ED intervention
New high grade AV block
Suspected acute coronary syndrome
Suspected myocarditis
Suspected Lyme carditis
Drug toxicity requiring monitoring
Observation pathway criteria
Observation considerations
Transient medication related bradycardia with resolved symptoms
Normalizing vitals after correction of reversible cause
Discharge criteria
Discharge requirements
Asymptomatic at rest and with brief ambulation when appropriate
No high risk ECG features
Reversible cause corrected or clearly identified with safe plan
Reliable follow up within 72 hours when indicated
Return precautions understood and feasible
Discharge Instructions
Copy discharge instructions
Patient facing instructions
Low heart rate was found and may cause dizziness or fainting
Avoid extra doses of heart rate lowering medications unless specifically instructed
Hydration and regular meals if dehydration contributed
Follow up timing
Primary care within 3 to 7 days
Cardiology within 7 to 14 days if ongoing low heart rate or abnormal ECG
Return to emergency department immediately for
Fainting
Chest pain
Shortness of breath
Confusion
Weakness worsening
Heart rate very low with symptoms
References
Guidelines and algorithms
Evidence based sources
American Heart Association
Adult bradycardia with a pulse algorithm
2025
American College of Cardiology
ACC AHA HRS guideline on bradycardia and conduction delay
2018
Circulation
Adult advanced life support guideline update
2025
Resuscitation Council UK
Adult bradycardia algorithm
2021
European Resuscitation Council
Guidelines on cardiopulmonary resuscitation
2025
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