Physiology and Pathophysiology of Syncope Flashcards

1
Q

Syncope

A

A specific form of transient loss of consciousness due to cerebral hypoperfusion, characterised by rapid onset, short duration and spontaneous recovery

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2
Q

Types of syncope

A

Reflex, cardiac and orthostatic

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3
Q

Transient Loss of Consciousness

A

A state of real or apparent loss of consciousness with loss of awareness, motor control. Short duration and results in amnesia

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4
Q

Types of reflex syncope

A

Vasovagal
Situation
Carotid Sinus

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5
Q

Causes of TLOC

A

Head trauma
Syncope
Epileptic seizure
TLOC mimics

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6
Q

Initial evaluation of TLOC

A

History
Full physical examination
Orthostatic BP measurement
12-lead ECG

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7
Q

Reflex syncope

A

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

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8
Q

Which type of syncope is the most common?

A

(vasovagal) reflex syncope

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9
Q

What happens when reflex pathways are activated?

A

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

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10
Q

What triggers vasovagal reflex syncope?

A

emotional or orthostatic stress

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11
Q

Symptoms of vasovagal reflex syncope

A

Typical prodrome (pallor, sweating, nausea)

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12
Q

How to avoid vasovagal reflex syncope?

A

increase venous return by crossing legs or adopting horizontal gravity neutralisation position

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13
Q

Risks of vasovagal reflex syncope

A

Injury when falling

* not associated with increased mortailtiy

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14
Q

Treatment for vasovagal reflex syncope

A

education
reassurance
avoiding triggers
adequate hydration

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15
Q

Situational reflex syncope

A

Faint during or immediately after a specific trigger eg coughing

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16
Q

Treatment of situational reflex syncope

A

treatment of cause eg cough
lie down
hydrate
cardiac permanent pacing

17
Q

Carotid Sinus Reflex Syncope

A

Triggered by mechanical manipulation of neck, tight collar etc.

eg after head and neck surgery

Common in elderly (esp males)

18
Q

Associated condition of carotid sinus reflex syncope

A

Carotid artery atherosclerosis

19
Q

Treatment of carotid sinus reflex syncope

A

Permanent cardiac pacing

20
Q

Cause of postural/ orthostatic hypotension

A

Failure of baroreceptor responses to gravitational shifts in blood when moving from horizontal to vertical position

21
Q

Risk factors for postural hypotension

A

Age
Medication
Reduced intravascular volume
Prolonged bed rest

22
Q

Positive result for postural hypotension

A

Drop within 3mins of standing from lying position:-

  • in SBP of at least 20mmHg (with or without symptoms)
  • in DBP of at least 10mmHg (with symptoms)
23
Q

Symptoms of postural hypotension

A

Lightheadedness, dizziness, blurred vision, falls

24
Q

Cardiac syncope

A

Syncope caused by a cardiac event which results in a sudden drop in CO

25
Q

Causes of cardiac syncope

A

Arrhythmias
Acute MI
Structural cardiac disease
Other CVD eg PE

26
Q

Features suggesting cardiac syncope

A

Presence of structural cardiac abnormality
Family history of sudden death at a young age
Palpitations followed by syncope
Syncope during excretion or when supine