Describe the physiology of a vasovagal syncope
Generally, there was a lack of knowledge about this topic with many candidates confusing
vasovagal syncope with a Valsalva or orthostatic hypotension. A “vasovagal” is from excessive
autonomic reflex activity in contrast to orthostatic hypotension which is a failure of the
autonomic reflex response.
A good place to start was with a description of vasovagal syncope, also known as
neurocardiogenic syncope. It is benign, self-limiting and caused by an abnormal or exaggerated
autonomic response to various stimuli (which should have been listed). The mechanism should
have been described including the various receptors involved.
Interestingly, though the official CICM answer draws a distinction between vasovagal syncope and orthostatic hypotension ("which is a failure of the autonomic reflex response"), orthostatic causes are listed in the 2018 ESC guidelines for the management of syncope. In fact they separated vasovagal syncope into "orthostatic" and "emotional", alongside several other forms of reflexive neurally mediated syncopes.
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