Fainting on exposure to phobic stimuli.

Two patients with phobias for medical procedures and trauma developed "vasovagal syncope" with hypotension and bradycardia while viewing a videotape of a venous cutdown. Eleven hours of exposure therapy per patient eliminated both the phobic and fainting responses. These facts support existing hypotheses that phobias of this type and vasovagal fainting are associated and that vasovagal syncope is a diphasic response. They do not support hypotheses that vasovagal syncope follows sudden cessation of anxiety, that that counter-conditioning is necessary for successful treatment, or that novel symptoms emerge following behavioral treatment of these phobias.