Vasovagal syncope and head upright tilt table testing

Syncope is a common medical complaint that is responsible for a significant number of emergency department visits and hospitalizations each year. A majority of syncopal events are believed to be caused by vasovagal responses. Although vasovagal syncope is essentially equivalent to simple fainting, the physiologic events that lead to this phenomena are complex. Although not completely understood, the most commonly held theory explaining vasovagal syncope involves a series of reflexive interactions between cardiac mechanoreceptors and the autonomic nervous system. Until the advent of head upright tilt table testing, diagnosis of vasovagal syncope has been an assumption, made when all other causes have been eliminated. Tilt table testing allows reproduction of the syncopal event in susceptible individuals and monitoring of the patients' physiologic responses during an episode. Direct observation and documentation of symptoms permit accurate diagnosis and yield information vital to treatment and symptom control.