The Postural Tachycardia Syndrome: Etiology, Diagnosis and Treatment

Zusammenfassung

Syncope, the transient loss of consciousness and postural tone, has long been recognized by medical science. Only relatively recently, however, was it established that many episodes of syncope were due to transient periods of auto-nomically-mediated hypotension and bradycardia. During the last 15 years, tilt-table testing has been employed as a useful modality for the diagnosis of these conditions, while simultaneously providing a controlled setting where precise observations and measurements of these phenomena could be made [1]. Thus, during this period there was a very rapid increase in our knowledge of these disorders. One such observation was that these transient disturbances in autonomic nervous system tone could produce varying degrees of hypotension, while not enough to result in loss of consciousness, could nonetheless be great enough to produce symptoms such as vertigo, dizziness, near-syncope and focal neurologic deficits that appeared remarkably similar to transient ischemic attacks. At the same time, several groups of investigators noted that there was a group of patients who exhibited a less severe form of autonomic disturbance, resulting in a form of orthostatic intolerance manifested by postural tachycardia, severe fatigue, blurred vision, exercise intolerance, dizziness and near-syncope. Detailed analysis of these patients uncovered the fact that their clinical histories, physical examinations, and responses to upright posture and head upright tilt were essentially similar.