Vasovagal syncope (CV)

Question 1

Define vasovagal syncope.

Answer 1

Loss of consciousness due to transient drop in blood flow to the brain caused by excessive vagal discharge

Question 2

What is vasovagal syncope also known as?

Answer 2

Common faint

Question 3

What is vasovagal syncope the most common cause of?

Answer 3

Fainting in young people

Question 4

What can vasovagal syncope be precipitated by?

Answer 4

• emotions:
  
  • severe pain
  • fear
  • blood phobia and other phobias
• orthostatic stress
  
  • prolonged standing
  • hot weather

Question 5

What does neurally mediated reflex syncope (NMRS) refer to? (vasovagal syncope)

Answer 5

A group of related conditions or scenarios in which symptomatic hypotension occurs as a result of neural reflex vasodilation and/or bradycardia

Question 6

What is vasovagal syncope a type of?

Answer 6

Neurally mediated reflex syncope

Question 7

What are the clinical features of vasovagal syncope? (7)

Answer 7

• loss of consciousness lasting a short time
• provocative factor
• vagal symptoms before passing out: dizziness, sweating, light-headedness
• twitching of limbs during blackout
• diminished vision/hearing
• recovery very quick (short post-ictal phase)
• absence of Fx of sudden death / structural heart disease (consider cardiac cause if so)

Question 8

What would you see on examination of vasovagal syncope?

Answer 8

Bradycardia at time of syncope

Question 9

What are some risk factors for vasovagal syncope? (8)

Answer 9

• prior syncope
• prior Hx of arrhythmias, MI, heart failure or cardiomyopathy
• severe aortic stenosis
• prolonged standing
• emotional stress
• dehydration
• preceding episode of N/V
• preceding episode of severe pain

Question 10

What are the 1st-line investigations for vasovagal syncope? (7)

Answer 10

• 12-lead ECG - rule out AV block, bradycardia, asystole, long QT, BBB
• serum Hb - anaemia
• plasma blood glucose - hypoglycaemia
• serum beta-hCG - pregnancy
• cardiac enzymes & D-dimer - MI, PE
• serum cortisol - adrenal insufficiency
• U&Es + creatinine - dehydration

Question 11

Why do we do ECG for vasovagal syncope?

Answer 11

Check for arrhythmias - rule out AV block, bradycardia, asystole, long-QT, BBB

Question 12

When should we do a 24h ECG for vasovagal syncope?

Answer 12

Should be requested in those with multiple episodes of loss of consciousness with quick recovery times

Question 13

Why do we check lying/standing BP in vasovagal syncope?

Answer 13

Check for orthostatic hypertension

Question 14

Why do we do echocardiogram in vasovagal syncope?

Answer 14

Check for outflow obstruction

Question 15

Why do we do fasting blood glucose in vasovagal syncope?

Answer 15

Check for DM / hypoglycaemia

Question 16

What mnemonic can be used to remember other tests to do for vasovagal syncope?

Answer 16

BRACES

• BNP>300picograms/mL
• Rectal exam positive for faecal occult blood
• Anaemia (Hb<90g/L)
• Chest pain associated with syncope
• ECG showing Q-waves
• oxygen Sats <95%

Question 17

What are some differential diagnoses for vasovagal syncope? (14)

Answer 17

• orthostatic syncope - concomitant dehydration, anti-hypertensive, vasodilator use, old and frail
• bradycardia
• SVT, VT, non-sustained VT
• ACS
• aortic dissection
• pulmonary hypertension
• pulmonary embolism
• aortic stenosis
• HOCM
• vertebrobasilar TIA
• subclavian steal
• migraine
• adrenal insufficiency
• hypoglycaemia

Question 18

What is the management plan for vasovagal syncope? (7)

Answer 18

• patient education + avoid triggers (e.g. prolonged standing, warm env)
• physical techniques: physical counter-pressure manoeuvres (e.g. squatting, arm tensing, leg crossing); tilt training (standing training)
• volume expansion - increased dietary salts, electrolyte-rich sports drinks
• consider fludrocortisone
• consider midodrine
• withdraw hypotensives
• lifestyle modification - avoid excess alcohol/caffeine/nicotine, regular physical activity

Question 19

What are some complications of vasovagal syncope? (1 + 2)

Answer 19

Falls:

• injuries and fractures
• extradural or cerebral haemorrhages (secondary to trauma)

Question 20

Describe the prognosis of vasovagal syncope. (2)

Answer 20

• recurrences are common but often occur in clusters
• in the long term, the mortality risk if very low, but injury is a concern due to recurrent falls, especially in older people