Physiology and Pathophysiology of Syncope Flashcards
Syncope
A specific form of transient loss of consciousness due to cerebral hypoperfusion, characterised by rapid onset, short duration and spontaneous recovery
Types of syncope
Reflex, cardiac and orthostatic
Transient Loss of Consciousness
A state of real or apparent loss of consciousness with loss of awareness, motor control. Short duration and results in amnesia
Types of reflex syncope
Vasovagal
Situation
Carotid Sinus
Causes of TLOC
Head trauma
Syncope
Epileptic seizure
TLOC mimics
Initial evaluation of TLOC
History
Full physical examination
Orthostatic BP measurement
12-lead ECG
Reflex syncope
All types of syncope in which neural reflexes modify HR (cardioinhibition) and/ or vascular tone (vasodepression), hence predisposing to a fall in MAP of sufficient severity to cause a transient period of cerebral hypoperfusion causing syncope/ near syncope
Which type of syncope is the most common?
(vasovagal) reflex syncope
What happens when reflex pathways are activated?
cardioinhibition via vagal stimulation-> bradycardia and decreased CO
Vasodepression via reduced sympathetic activity to blood vessels> decreased SVR, venous return, SV and CO
MAP decreases as CO and SVR falls-> cerebral hypoperfusion->syncope/ near syncope
What triggers vasovagal reflex syncope?
emotional or orthostatic stress
Symptoms of vasovagal reflex syncope
Typical prodrome (pallor, sweating, nausea)
How to avoid vasovagal reflex syncope?
increase venous return by crossing legs or adopting horizontal gravity neutralisation position
Risks of vasovagal reflex syncope
Injury when falling
* not associated with increased mortailtiy
Treatment for vasovagal reflex syncope
education
reassurance
avoiding triggers
adequate hydration
Situational reflex syncope
Faint during or immediately after a specific trigger eg coughing