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Postural orthostatic tachycardia syndrome (POTS) is one of a group of disorders that have orthostatic intolerance (OI) as their primary symptom.OI describes a condition in which an excessively reduced volume of blood returns to the heart after an individual stands up from a lying down position.n POTS, the lightheadedness or fainting is also accompanied by a rapid increase in heartbeat of more than 30 beats per minute, or a heart rate that exceeds 120 beats per minute, within 10 minutes of rising. The faintness or lightheadedness of POTS are relieved by lying down again.
The hallmark symptom of POTS is an increase in heart rate by at least 30 beats per minute within 10 minutes of assuming an upright position. For people aged between 12 and 19, the minimum increase for diagnosis is 40 beats per minute. This symptom is known as orthostatic (upright) tachycardia (fast heart rate).ther symptoms of an orthostatic nature â occurring in response to upright posture â may accompany the tachycardia. The causes of POTS are poorly understood, and it is likely that several distinct underlying problems can lead to the symptoms of POTS.