What is Postural Tachycardia Syndrome (POTS)?
When orthostatic symptoms occur in patients, but blood pressure does not fall as much as 20/10 mmHg on assumption of upright posture, the patient has orthostatic intolerance (OI). Additional criteria used for the diagnosis of OI at Vanderbilt’s Autonomic Dysfunction Center include an increase in heart rate of at least 30 beats per minute with standing, and a standing plasma norepinephrine level of at least 600 pg/ml. Because upright heart rate is usually greatly increased, the term Postural Tachycardia Syndrome (POTS) is commonly used.
