title: Reversible sympathetic vasomotor dysfunction in POTS patients.
abstract: BACKGROUND
  Orthostatic intolerance refers to the development upon assuming an upright posture of disabling symptoms, which are partly relieved by resuming the supine position. Postural tachycardia syndrome (POTS) is an orthostatic intolerance syndrome characterized by palpitations due to excessive orthostatic sinus tachycardia, lightheadedness, tremor, and near-syncope. Patients usually undergo extensive medical, cardiac, endocrine, neurological and psychiatric evaluation, which usually fails to identify a specific abnormality. We investigated the autonomic and hemodynamic profile of POTS patients and the efficacy of bisoprolol and or fludrocortisone.
  
  
  RESULTS
  We evaluated eleven female patients with POTS before and after medical treatment with a cardio-selective beta blocker (bisoprolol) and/or fludrocortisone, and eleven age-matched controls. Variability of heart rate and systolic blood pressure was assessed by Fast Fourier Transform, and spontaneous baroreceptor gain by temporal sequences slope and alpha index. Modelflow was used to quantify hemodynamics. All patients improved greatly after medication. The autonomic and hemodynamic impairment observed in patients with POTS, particularly after orthostatic stress, is treated effectively with bisoprolol and/or fludrocortisone. These results need further confirmation in a controlled double-blind study.
  
  
  CONCLUSIONS
  Proper medical treatment dramatically improves the clinical and autonomic/hemodynamic disturbances observed in patients with POTS. The data support the hypothesis that POTS is due to a hyperadrenergic activation and/or hypovolemia during orthostasis.
authors.affiliation: Centro de Estudos da Função Autonómica do Hospital de São João do Porto, Portugal. jfreitas@med.up.pt
authors.forename: J
authors.initials: J
authors.lastname: Freitas
authors.forename: R
authors.initials: R
authors.lastname: Santos
authors.forename: E
authors.initials: E
authors.lastname: Azevedo
authors.forename: O
authors.initials: O
authors.lastname: Costa
authors.forename: M
authors.initials: M
authors.lastname: Carvalho
authors.forename: A F
authors.initials: AF
authors.lastname: de Freitas
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D017298:Bisoprolol / Q000627:therapeutic use; D002302:Cardiac Output; D016022:Case-Control Studies; D005260:Female; D005438:Fludrocortisone / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D008901:Mineralocorticoids / Q000627:therapeutic use; D011187:Posture / Q000502:physiology*; D013575:Syncope / Q000209:etiology / Q000503:physiopathology; D013610:Tachycardia / Q000188:drug therapy / Q000503:physiopathology*; D014655:Vascular Resistance
chemical_list: D000319:Adrenergic beta-Antagonists; D000893:Anti-Inflammatory Agents; D008901:Mineralocorticoids; D005438:Fludrocortisone; D017298:Bisoprolol