Cardiorespiratory dynamics during vasovagal syncope induced by a head-up tilt.

Abstract
Cardiac output, ventilation volume and arterial pressure of an orthostatically unstable subject were recorded during an attack of vasovagal syncope induced by a passive tilt. The failure of circulatory homeostasis in the upright position may be ascribed to the depressor reflex initiated from the intracardiac baroreceptor.