Sinus Bradycardia

Sinus Bradycardia

David Ray Velez, MD

A Slowed Regular Heart Rate Originating in the Sinoatrial (SA) Node with Rate < 60 bpm

  • Can Be a Normal Adaptive Response, Particularly While Sleeping

EKG Pattern

  • HR < 50-60 bpm
  • Normal P Waves

Sinus Bradycardia

Pathologic Causes

  • Myocardial Infarction (MI)
  • Electrolyte Derangements
  • Obstructive Sleep Apnea (OSA)
  • High Resting Vagal Tone – Athletes
  • Vagal Stimulation – Pain
  • Hypothyroidism
  • Hypothermia
  • Infection
  • Sick Sinus Syndrome/Sinus Node Dysfunction
  • Anorexia Nervosa
  • Brainstem Herniation (Cushing Reflex)
  • Medications (Beta-Blockers, Calcium Channel Blockers, Opiates, etc.)

Treatment

  • The Majority Require No Specific Treatment
  • Atropine
    • Indications:
      • Hemodynamic Instability
      • Signs of Shock
      • Ischemic Chest Discomfort
      • Acute Heart Failure
      • Acute Altered Mental Status
    • Dose: 1 mg IV, Repeated Every 3-5 Minutes as Needed (Up to a Total Dose of 3 mg)
  • Options if Atropine Fails:
    • Temporary Cardiac Pacing
    • Dopamine Infusion
    • Epinephrine Infusion
  • *See Antiarrhythmic Pharmacology