Medical director: Doc. Cinchini Elisabetta



Published in the issue of August / September 2014 of the international journal Journal of Atrial Fibrillation, an article entitled "Vasovagal Syncope As A Manifestation Of An Evolutionary Selected Trait" by dr. Paolo Alboni in collaboration with dr. Marco Alboni.

  • Paolo Alboni - Section of Cardiology and Syncope Unit, Ospedale Privato Quisisana, Ferrara, Italy.
  • Marco Alboni - Department of Zoology and Anthropology, University of Sassari, Italy. 


Some observations suggest that typical (emotional or orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. We conducted an extensive bibliographic research on the vasovagal reactions in animals, including humans, in order to investigate the possible factors that may explain the origin and evolution of VVS.

We found two processes which appear relevant for the investigation of VVS evolution: fear/threat bradycardia (alarm bradycardia) in animals, mainly during tonic immobility and vasovagal reflex during hemorrhagic shock (thoracic hypovolemia) both in animals and humans. The available data suggest that VVS in humans, alarm bradycardia in animals and the vasovagal reflex during hemorrhagic shock share the same physiological mechanisms and that is indicative of a common evolutionary root.

However, during the vasovagal reflex loss of consciousness occurs in humans, but it is absent (or extremely rare) in animals. That can be explained as a by-product due to the erect position and the large brain evolved in our species. If the vasovagal reflex persisted for millions of years along the vertebrates evolutionary history, we can reasonably assume that it has a function and it is not harmful. It could be neutral or beneficial, but the available data suggest it is beneficial; likely, it evolved as an advantageous response to stressful and possibly dangerous heart conditions. Emotional or orthostatic vasovagal reflex is preceded by enhanced sympathetic activity, which is harmful and possibly dangerous.

The transient inhibition of the sympathetic system, together with activation of the vagal tone, characterizes VVS. The consequent slowing of the heart rate induced by the vasovagal reflex may constitute a beneficial break of the cardiac pump, thereby reducing myocardial oxygen consumption. We suggest that typical VVS should be regarded as a selected response, which probably evolved in the ancient past as a defense mechanism of the organism within some ancestral group(s) of vertebrates.

Download the abstract here.

Other posts from the same category

Book your visit online

Quisisana offers the possibility of booking specialist visits directly online


We and selected third parties use cookies or similar technologies for technical purposes and, with your consent, also for other purposes as specified in the cookie policy.
If you close this banner with a tick or click on "Decline", only technical cookies will be used. If you want to select the cookies to be installed, click on 'Customise'. If you prefer, you can consent to the use of all cookies, including cookies other than technical cookies, by clicking on "Accept all". You can change your choice at any time.