title: Disturbances of gastrointestinal transit and autonomic functions in postural orthostatic tachycardia syndrome.
abstract: BACKGROUND
  Gastrointestinal symptoms are common in the postural orthostatic tachycardia syndrome (POTS). However, few studies have evaluated gastrointestinal transit in POTS. Our primary objectives were to evaluate gastrointestinal emptying and the relationship with autonomic dysfunctions in POTS.
  
  
  METHODS
  We reviewed the complete medical records of all patients aged 18 years and older with POTS diagnosed by a standardized autonomic reflex screen who also had a scintigraphic assessment of gastrointestinal transit at Mayo Clinic Rochester between 1998 and 2012. Associations between specific gastric emptying and autonomic (i.e., cardiovagal, adrenergic, and sudomotor) disturbances were evaluated.
  
  
  RESULTS
  Among 163 patients (140 women, mean [± SEM] age 30 [± 1] years), 55 (34%) had normal, 30 (18%) had delayed, and 78 (48%) had rapid gastric emptying. Fifty-eight patients (36%) had clinical features of physical deconditioning, which was associated (p = 0.02) with rapid gastric emptying. Associations with delayed gastric emptying included vomiting, which was more common (p < 0.003), and anxiety or depression, which was less common (p = 0.02). The tilt-associated increase in heart rate and reduction in systolic BP at 1 min was associated (p < 0.05), being greater in patients with delayed gastric emptying.
  
  
  CONCLUSIONS
  Two-thirds of patients with POTS and GI symptoms had abnormal, most frequently rapid gastric emptying. Except for more severe adrenergic impairment in patients with delayed gastric emptying, the pattern of autonomic dysfunction did not discriminate among gastric emptying groups. Further studies are necessary to ascertain whether extravascular volume depletion and/or deconditioning contribute to POTS in patients with gastrointestinal symptoms.
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors.forename: A
authors.initials: A
authors.lastname: Loavenbruck
authors.forename: J
authors.initials: J
authors.lastname: Iturrino
authors.forename: W
authors.initials: W
authors.lastname: Singer
authors.forename: D M
authors.initials: DM
authors.lastname: Sletten
authors.forename: P A
authors.initials: PA
authors.lastname: Low
authors.forename: A R
authors.initials: AR
authors.lastname: Zinsmeister
authors.forename: A E
authors.initials: AE
authors.lastname: Bharucha
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D005260:Female; D005772:Gastrointestinal Transit / Q000502:physiology*; D018589:Gastroparesis / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D054972:Postural Orthostatic Tachycardia Syndrome / Q000150:complications / Q000503:physiopathology*
keywords: POTS; dumping; gastric emptying; gastroparesis