Loss of consciousness: a state characterized by the loss of awareness of self and the surroundings and an inability to respond to stimuli

Transient loss of consciousness: a temporary (short duration) and self-limited form of loss of consciousness; A term used predominantly during clinical evaluation while the pathogenesis is still unclear.

Syncope (fainting): Due to Cerebral hypoperfusion resulting in

• transient loss of consciousness – TLOC)
• Loss of muscle tone
• Spontaneous recovery without treatment
• Completely back to baseline

<aside> 💡 7s cerebral flow cessation systolic BP 55mmHG @ heart level systolic BP of 45mmHg @ Head level

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Prodrome with noncardiogenic

1. tunnel vision - retinal hypoperfusion
2. nausea, sweating pallor, palpitations - autonomic actication
3. light headedness - early cerebral hypoperfusion
4. distant sounds, buzzing, ringing - final cerebral hypoperfusion
5. LOC - syncope

3 major categories

• neurogenic/reflex: most common. benign and usually self-limiting.
  • Emotional trigger - fear, pain, phobia
  • Visceral or somatic trigger (situational). could be on micturition, defecation, swallowing, cough, sneeze, valsalva.
  • stretch receptor trigger - carotid sinus syndrome
  • cause vasovagal response: excess stimulation of vagus nerve causing bradycardia, vasodilation and syncope
  • Reflex-mediated and orthostatic causes of syncope occur more frequently and tend to be more benign than cardiac and vascular causes.
• orthostatic: mostly in elderly esp with meds. inadequate SNS tone. increased venous pooling, low circulating blood volume, inadequate vasoconstriction standing up.
  • drug induced - alcohol, vasodilators, diiuretics, beta blockers
  • hypovolemia - haemorrhage, diarrhoea, vomiting
  • autonomic failure
    • primary (brain): Parkinsons, Lewy body dementia
    • secondary (nerves): AI, diabetes
  • inadequate sypathetic outflow → insufficient vasoconstriction and chronotropic incompetence
• cardiogenic - WOBBLER ECG assessment
  • Arrhythmia
    • Bradycardia: sick sinus, asystole, Heart block
    • Tachycardia: VT/VF, SVT, AF
    • also WPW, long QT, Brugada, ARVD which can all deteriorate to VT
  • Structural
    • Valve: aortic stenosis, pulmonary stenosis
    • Ventricle: hypertrophic cardiomyopathy, myocarditis, dilated cardiomyopathy, MI
    • Vessel: MI, PE, aortic dissection