The Online Encyclopedia and Dictionary






Postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (or POTS) is a condition of orthostatic intolerance in which a change from the supine position to an upright position causes an abnormally high increase in heart rate.



The syndrome was identified as such by Schondorf and Low in 1993. Similar symptoms were collectively described as "idiopathic hypovolemia" by Fouad in 1986.


The sudden increase in heart rate upon standing is often accompanied by hypotension, and associated with dizziness, fatigue, and nausea.

Affected population

About 80 percent of patients diagnosed with POTS are female.


The causes of POTS are not fully known. It is generally believed to be a case of dysautonomia. Its onset is sometimes associated with an inflammatory condition such as a viral infection. An overlap of symptoms with Chronic fatigue syndrome may suggest a pathological overlap in some cases.


Head-up tilt table test

A head-up tilt table test consists of a patient resting, strapped to a table in the supine position for several minutes. The table will then be tilted to a nearly vertical position. Heart rate and blood pressure are measured in both positions. The standard for diagnosis is usually the heart rate experiencing a sustained increase of at least 30 beats per minute, or an sustained increase to a total of at least 120 beats per minute.


Schondorf R, Low PA. Idiopathic postural orthostatic tachycardia syndrome: an attenuated form of acute pandysdautonomia? Neurology. 1993;43:132-137.

External Links

POTS Place

Last updated: 05-21-2005 19:40:20