Vasovagal Syncope

i.e. the common faint. To date, I have never fainted and as a kid, I thought the idea of fainting (and of breaking a bone) was pretty cool.

And at last, it is bedtime. Yay 🙂


Vasovagal Syncope

Definition: a.k.a neurocardiogenic syncope, a.k.a a simple faint.

Syncope, a temporary impairment of consciousness due to inadequate cerebral blood flow, is more commonly referred to as a blackout.

Aetiology/risk factors:

-due to reflex bradycardia +/- peripheral vasodilation provoked by emotion, pain, fear or standing too long, especially in warm surroundings.

Epidemiology: very common

Symptoms & Signs: onset is over seconds (not instantaneous)

-often precede by nausea, pallor, sweating, closing in of visual fields (pre-syncope)

It cannot occur if lying down.

-individual falls to the ground, being unconscious for ∼ 2 minutes.

-brief clonic jerking of the limbs may occur (reflex anoxic convulsions due to cerebral hypoperfusion), but there is no stiffening or tonic (stiffening)/clonic (rhythmical jerking) sequence.

-urinary incontinence uncommon (but can occur)

-no tongue-biting

-recovery is rapid

-bradycardia and hypotension during episode

Investigations:

Investigations mainly to rule out other causes of syncope, particularly if persistent.

-Cardiovascular and neurological examination, sitting and standing blood pressure (orthostatic hypotension?)

U&Es, FBC, Glucose (hypoglycaemia?)

ECG/ 24h ECG (dysrhythmia?)

Echo (structural heart disease?)

Tilt testing is used to diagnose vasovagal syncope if there are repeated episodes of unexplained syncope and cardiac causes or epilepsy have been excluded. The patient lies strapped flat on a swivel motorised table. BP, HR, symptoms and ECG are recorded after the table is tilted +60º to the vertical for 10-60 mins. Reproduction of symptoms, bradycardia or hypotension indicates a positive test.

Image result for tilt testing

Management:

-re-assure patient

-patient education, avoidance of triggering factors, sufficient hydration

-physical techniques to abort syncope when warning symptoms are recognised e.g. squatting, arm tensing, leg crossing and leg crossing with tensing of the lower body muscles.

Medical therapy rarely needed and clinical evidence to support use of drugs is weak:

-volume expansion e.g. increased dietary salt and electrolyte-rich sport drinks

-fludrocortisone (mineralocorticoid steroid)

-midodrine (vasopressor)

Complications: I suppose, if you fainted somewhere dangerous…and if they were very frequent

Prognosis: good

References: Cheese & Onion, Kumar & Clark’s, BMJ best practice

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