Postural orthostatic tachycardia syndrome (POTS) is manifested by a significant increase in heart rate (an increase of more than 30 bpm or a heart rate of 120 bpm or more) during postural challenge without a fall in blood pressure (it can be quite variable). The mechanism of POTS is incompletely understood and is associated with physical deconditioning, and it usually happens in young females.
In Europe, chronic fatigue syndrome (CFS) is called myalgic encephalomyelitis (ME). Orthostatic intolerance is a broad title for blood pressure abnormalities such as neurally mediated hypotension (NMH) and POTS. Orthostatic intolerance is a symptom of CFS.Patients with CFS have findings similar to the findings in patients with POTS during the head up tilt table test.18,19 Patients with POTS may also have fatigue as a prominent clinical feature. Orthostatic tachycardia and autonomic abnormalities are present in both conditions, which is qualitatively difficult to differentiate.
Patients should be advised to take aerobic exercise on a regular basis so that venous return from the lower extremities can be increased.21 Patients with dysautonomic syncope can be advised to wear graded compressive hosiery extending up to the waist, thus helping to increase static pressure at the calf and decrease venous pooling. A high fluid intake should be encouraged with at least 3–5 g of common salt.