Postural orthostatic tachycardia syndrome: an underrecognized disorder

Postural orthostatic tachycardia syndrome (POTS), a clinical syndrome of orthostatic intolerance characterized by excessive tachycardia and symptoms of cerebral hypoperfusion on standing, is not well recognized in Australia. The aim was to study the clinical symptomatology, results of autonomic testing and outcome in patients with POTS.

Sixteen subjects from a tertiary referral centre who met the criteria for POTS were studied between January 2003 and January 2006. Ten of these patients consented to be interviewed using a validated autonomic symptom questionnaire. Heart rate responses to deep breathing and the Valsalva manoeuvre were measured using Colin BP-508 machine (WR Medical Electronic Co., Stillwater, MN, USA). Tilt studies were carried out for 10 min to 80 degrees of head-up tilting. Patient outcome was assessed as functionally normal, able to stand 30 min without symptoms, able to work and carry out recreational activities or worse on follow up.

The mean age of 10 subjects was 24.9 +/- 6.8 years, six being women. The mean duration of symptoms was 70.7 months (range 3-228 months). The common presenting orthostatic symptoms were light-headedness (100%), palpitations (90%), pallor (90%), weakness (80%) and clammy skin (80%). The mean heart rate increment during the tilt study was 51.7 +/- 14.3 b.p.m. The mean duration of follow up was 8.9 months (range 1-16 months). Only five patients were functioning normally at the follow-up visit.

POTS is an underrecognized but persistent autonomic disorder in young patients with a variety of symptoms and variable outcome.