Bradycardia

Overview

  • Bradycardia refers to heart rate <60/min in an adult
  • Bradycardias are classified as regular or irregular, narrow complex or wide complex

Differential diagnosis causing bradycardia

  • Cardiac disease
    • Myocardial ischaemia / infarction
    • Myocarditis
    • Cardiomyopathies
  • Hypoxia
  • Electrolyte disturbance - Hyperkalemia
  • Medications, poisonings and toxic exposures
    • Digoxin
    • Beta blockers
    • Calcium channel blockers
    • Amiodarone
    • Clonidine
  • Hypothermia
  • Hypothyroidism
  • Raised intracranial pressure (Cushing response)
  • Infections (Lyme disease, diphtheria, typhoid fever)
  • Autoimmune - Systemic lupus erythematosis
  • Infiltrative disorders (e.g. sarcoidosis, amyloidosis)
  • Physiological causes
    • athletes
    • vagal response
Remember Life threatening causes of bradycardia include: hypotension, raised intracranial pressure and MI

History

  • Past medical history
  • Cardiac history and risk
  • Medical conditions - screen for
    • Hypothyroidism
    • Autoimmune/ infiltrative disease
  • Medication - digoxin, beta-blocker, calcium channel blockers or other antiarythmics

Examination

  • General observation
  • Vitals
    • Low body temperature?
    • Cushings triad
  • ECG
    • Hyperkalaemia - Tall tented T-waves
  • Cardiovascular examination
  • Respiratory examination

Acute Management

  • ABCD
    • Oxygen
    • IV access
  • Tredenleberg position if hypotensive
  • ECG
  • Drug: Atropine
  • Transthoracic pacing
  • Low dose adrenaline infusion - if transthoracic pacing unavailable
  • CPR - if deteriorating
Pharmacology Atropine

Investigations

  • FBC
  • EUC
    • Hyperkalaemia
  • LFT
  • CRP
  • Cardiac biomarkers
  • Cardiac ultrasound
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