Syncope refers to a transient loss of consciousness due to a sudden fall in blood pressure that temporarily impairs the blood supply to the brain. The most frequent cause of hypotension and syncope (fainting) in apparently normal individuals is neurally mediated syncope, which may also be referred as vasovagal, vasodepressor, neurocardiogenic or reflex syncope. Neurally mediated syncope is an acute hemodynamic reaction produced by a sudden change in the normal pattern of autonomic nervous system activities that maintains blood pressure in the standing posture. Sympathetic activity suddenly decreases while parasympathetic acutely increases. This results in a fall in blood pressure and slowing of the heart.
Neurally mediated syncope occurs more often in young women and the elderly. It can be triggered by emotions, blood loss, dehydration and prolonged standing. It is a benign condition that can be successfully managed, in most cases, with patient education and other non-pharmacologic approaches.
We focus on the diagnosis and management of patients with chronic fainting.
We have conducted several studies on fainting, including a double-blind placebo controlled trial of midodrine, studies on the role of breathing changes in susceptibility to fainting, and trials of water drinking to prevent fainting.