Time out of mind

Reply to the letter to the Editor of Marx et al

“…We greatly appreciate the Letter to the Editor sent by Marx et al in the comment on Kohno et al and Fedorowski and Sutton and the opportunity to reply offered by the Editor. Dr Marx and colleagues argue that vasovagal syncope (VVS) is a self‐preservation mechanism logically related with epinephrine (but not norepinephrine) surge.…”

Epinephrine rise concept

“…We very much appreciated both the letter from Marx et al regarding our recent article in the Journal of Cardiovascular Electrophysiology , and the Editor's offering us an opportunity to respond. The observations by Marx et al regarding apparent vasovagal syncope (VVS) events in children and adolescents tend, as they state, to be consistent with the potential role of epinephrine as a contributor to enhancing susceptibility to, and perhaps even being in part responsible for triggering, VVS events under conditions of emotional upset or stress. Additional indirect evidence favoring the “epinephrine rise” hypothesis is provided to some extent by the findings of the POST study in which beta‐adrenergic blockade appeared to provide some therapeutic benefit .…”

“…Marx et al raise the interesting issue that the unique VVS susceptibility exhibited by humans may tie into the epinephrine hypothesis. As they point out, we and others have commented previously on the seeming paradoxical persistence of VVS throughout the human evolutionary experience, while it is no longer (or perhaps never was) present in the vast majority of other species .…”