Syncope

Transient loss of consciousness due to cerebral hypoperfusion, characterized by rapid onset, short duration, and spontaneous complete recovery

Reflex syncope

  • Involves neural reflexes
  • Vagal stimulation decreases HR which decreases CO AND/OR
  • Depression of sympathetic activity to blood vessels - vasodilation, which decreases SVR, venous return, SV and CO
  • Decrease in CO and SVR → decreased MAP → syncope

Vasovagal syncope

  • Most common
  • Faint triggered by emotional distress or orthostatic stress
  • Associated with pallor, sweating and nausea
  • Can be averted through manoevers to increase venous return e.g. horizonal gravity neutralisation position
Management
  • Education
  • Reassurance
  • Avoidance of triggers
  • Adequate hydration

Situational reflex syncope

  • Faint during/immediately after a specific trigger e.g. cough
Management
  • Treat cause if possible
  • Advise patient to lie down if possible when experiencing trigger
  • Avoid dehydration and excessive alcohol
  • Cardiac permanent pacing may be required in some cases

Carotid sinus reflex syncope

  • Triggered by mechanical manipulation of the neck, shaving, tight collar etc.
  • More common in the elderly, especially males
Management
  • Cardiac permanent pacing

Orthostatic hypertension (postural hypertension)

  • Results from failure of baroreceptor responses to gravitational shifts in blood, when moving from horizonal to vertical position
  • Risk factors include being elderly, certain medications, certain diseases, reduced intravascular volume and prolonged bedrest
  • A positive result is indicated by a drop within 3 minutes of standing from a lying position:
    • In systolic BP of at least 20 mmHg with or without symptoms OR
    • In diastolic BP of at least 10 mmHg with symptoms
  • Symptoms - light headedness, dizziness, blurred vision, faintness and falls

Cardiac syncope

  • Cardiac event causing sudden drop in CO e.g. arrhythmias, MI