syncope Flashcards

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1
Q

what is syncope

A

transient loss of consciousness due to global cerebral hypoperfusion; acute onset and spontaneous complete recovery

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2
Q

what systolic BP results in syncope

A

<70mmHg

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3
Q

what is the most common form of syncope

A

vasovagal syncope

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4
Q

causes of transient loss of conciousness (5)

A

traumatic;
non-truamatic - syncope, elipepsy, psychogenic, misc (e.g. metabolic, toxins, haemorrhage etc.)

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5
Q

how to distinguish syncope from other TLOCs

A

syncope - rapid onset, short duration, spontaneous, complete recovery;
others are not characterised by these

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6
Q

4 syncope categories

A

reflex (60%); orthostatic (15%); cardiac; unkown

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7
Q

3 types of reflex syncope

A

vasovagal; situational; carotid sinus syndrome

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8
Q

reflex syncope - what triggers it, warning signs, who it occurs in

A

occurs due to a trigger e.g. emotional stress, injury, pain etc.
warning - there is a prodrome which lasts 30s-several mins where the pt feels fatigued, sweaty, dimming of vision, ringing in ears;
occurs in younger pts

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9
Q

vasovagal syncope pathway

A

trigger (exaggerated sympathetic activation) leading to –> increased vagal tone/prarsympathetic stimulation –> bradycardia, vasodilation of peripheral blood vessels –> hypotension –> cerebral hypoperfusion –> loss of conciousness

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10
Q

common triggers of vasovagal syncope (5)

A

pain; prolonged standing; fear; dehydration; stressful events

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11
Q

symptoms of vasovagal syncope

A

dizziness; fainting; feeling warm; nausea; ringing in ears; tunnel vision etc.

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12
Q

what is situational syncope

A

a form of reflexive syncope caused by specific situational triggers

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13
Q

examples of situational syncope (5)

A

micturition; defaecation; coughing; laughing; swallowing

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14
Q

who does micturition syncope affect more and what is the mechanism

A

affects men - usually benign in young men but associated with comorbidities.postural hypotension in older;
occurs when stretch receptors innervate the brainstem which upregulates parasymp.

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15
Q

what is the carotid sinus reflex

A

the carotid sinus is a dilation at the base of the internal carotid artery that contains baroreceptors which monitor BP

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16
Q

carotid sinus reflex pathway (2)

A
  1. ↑ BP –> ↓ symp. –(vasodilation)–> ↓TPR –> ↓BP
  2. ↑ BP –> stretch carotic barorecptors –> message sent to brainstem –> ↑ parasymp – (↓ HR + contractility)–> ↓ CO –> ↓BP
17
Q

what can be done to test the carotid sinus reflex

A

carotid sinus massage - a normal response is a slight drop in HR/BP, an exaggerated response indicates carotid sinus hypersensitivity

18
Q

what is carotid sinus syndrome

A

syncope without warning and hypersensitive CSM response (and reproducable syncope w CSM)

19
Q

carotid sinus syndrome triggers examples (3)

A

head turning; shaving; tight collar (too much pressure on CS)

20
Q

what can help exaggerated CSM

A

pacing

21
Q

what is orthostatic hypotension

A

a form of low blood pressure that happens when standing after sitting or lying down - compensatory mechanisms are required to maintain BP as blood volume is redistributed around the body

22
Q

orthostatic hypotension definition (stats)

A

↓systolic BP >20mmHg within 3mins of standing or a systopic BP of <90mmHg on standing

23
Q

How is the arterial blood pressure adjusted as someone stands up after being in a lying
position?

A

When someone stands up the venous return falls due to gravity, Cardiac input diminishes and
arterial BP is reduced (↓preload​) => Baroreceptors​ afferent firing is reduced – medullary centres inhibition reduced -> ↑sympathetic tone to arterioles and veins (vasoconstriction​), Reduced vagal tone to SAN =>
↑myocardial sympathetic tone –> ↑HR -> ↑stroke work –> ↑ blood pressure

24
Q

what occurs when standing up when there is no compensation

A

↓venous return -> ↓underfilled LV -> ↓SV -> ↓CO -> ↓BP

25
Q

causes of OH (3)

A
  1. drugs e.g. antihypertensives, antiparkinsonian, antianginals etc.
  2. hypovolaemia (dehydration, addison’s disease)
  3. autonomic failure - primary (Parkinson’s), secondary (ageing, diabetes)
26
Q

when are OH symptoms worse

A

on standing; in the morning; after meals; after exercise; in hot environments

27
Q

management of reflex syncope and OH (8)

A

reassurance; education; lifestyle changes; counter-pressure manouvers (e.g. squatting); increase fluid intake; reduce BP lowering drugs; pacing (select pts only); fludrocortisone (select pts only)

28
Q

when is pacing considered in reflex syncope

A

recurrent syncope despite medical therapy + brady/asystolic pauses; only benefits those with bradycardia

29
Q

what causes cardiac syncope

A

arrythmia (2/3) e.g. AV block, SVT; structural (1/3) e.g. AS, PE, HOCM

30
Q

red flag symptoms for syncope (history/PMH -6)

A

history - exertion (AS, coronary ischaemia), supine, no warning;
PMH - structural heart disease, CAD, HF

31
Q

red flag symptoms for syncope (FH, associated - 6)

A

FH - sudden cardiac death;
associated - chest pain, palpitations, SOB, abdo pain, headache

32
Q

red flag symptoms for syncope (examination, ECG -8)

A

examination - low BP, bradycardia, undiagnoses systolic murmur;
abnormal ECG - long QT, brugada sign (or other channeopathies), conduction disease, arrythmia, acute MI

33
Q

6Ps for syncope history

A

before - provoking factors, posture, prodrome, PMH (+DH,FH);
during - passerby account
after - post event (rapid recover etc.)

34
Q

what is the tilt table test

A

a test used to provoke reflex syncope in a lab setting; pt starts off supine and gradually tilted to upright position –> +ve test will result in ↓systolic BP (vasodepressor) or ↓HR (cardioinhibitory) or ↓BP +↓HR (mixed)

35
Q

why is the tilt table test rarely used

A

time consuming and it is a very artificial investigation

36
Q

role of cardiac rhythm monitoring

A

if arrythmia is suspected and symptoms are frequent (holter) or infrequent (loop recorder)