Bradycardia (aka bradyarrhythmia) is a slow heart rate

• Resting HR<60bpm in adults
• Relative bradycardia is heart rate that, although not actually below 60bpm, is still considered too slow for the patient's current medial condition

• Usually asymptomatic, until the rate is <50bpm
• Fatigue
• Weakness
• Diziness
• Fainting, at very low rates

• Physiological:
  • During sleep, a slow HR between 40-50bpm is common and considered normal
  • Highly trainted athletes may have athletic heart syndrome, a very slow resting HR that occurs due to sport adaptation, and helps prevent tachycardia during training
• Cardiac, which includes Acute/chronic ischemic heart disease, Vascular heart disease, Valvular heart disease, or Degenerative primary electrical disease. Causes include:
  • Disorders of the SA node (aka sick sinus syndrome), which may have disordered automaticity or impaired conduction of the impulse from the sinus node into the surrounding atrial tissue (an exit block).
  • Disorders of the AV node, which may have impaired conduction in the AV node, or anywhere below it (e.g. Bundle of His). AV blocks are clinically more significant than SA blocks
• Noncardiac, including:
  • Drugs, including beta blockers, which can slow the heart rate and decrease how forcefully it contracts
  • Recretional drug use/abuse
  • Metabolic or endocrine issues, especially in the thyroid
  • Electrolyte imbalance
  • Neurologic factors
  • Autonomic reflexes
  • Situational factors, e.g. prolonged bed rest
  • Autoimmunity

• Palpation
• ECG
• Electrolytes → determine underlying cause

Source: RNCeus

• ABC's, including:
  • Supplemental oxygen if oxygen saturations are low
  • IV atropine
  • If ineffective, IV inotrope infusion (e.g. dopamine, adrenaline)
  • Transcutaneous pacing, if the cause of bradycardia is not rapidly reversible

• More likely to have acquired it (cf being congenital)
• More common in older Pt's

• Heart rate
• Tachycardia (antonym)
• Bradypnea (slow breathing)