What is the vasovagal syndrome?

Simple faint. Vasovagal syncope is the most common cause of a simple faint. It is a neurocardiogenic response whereby a trigger ( ie blood draw, dentist drill) cause a surge of adrenaline causing a strong heart beat which feeds back on the vagus nerve that then leads to a chagall stimulation which cause dilatation of the blood vessel (lowers blood pressure) and slow heart rate.