title: Decreased orthostatic adrenergic reactivity in non-dipping postural tachycardia syndrome.
abstract: Whether non-dipping - the loss of the physiologic nocturnal drop in blood pressure - among patients with postural tachycardia syndrome (POTS) is secondary to autonomic neuropathy, a hyperadrenergic state, or other factors remains to be determined. In 51 patients with POTS (44 females), we retrospectively analyzed 24-hour ambulatory blood pressure recordings, laboratory indices of autonomic function, orthostatic norepinephrine response, 24-hour natriuresis and peak exercise oxygen consumption. Non-dipping (<10% day-night drop in systolic blood pressure) was found in 55% (n=28). Dippers and non-dippers did not differ in: 1) baseline characteristics including demographic and clinical profile, sleep duration, daytime blood pressure, 24-hour natriuresis, and peak exercise oxygen consumption; 2) severity of laboratory autonomic deficits (sudomotor, cardiovagal and adrenergic); 3) frequency of autonomic neuropathy (7/23 vs. 8/28, P=0.885); 4) supine resting heart rate (75.3±14.0bpm vs. 74.0±13.8bpm, P=0.532); or 5) supine plasma norepinephrine level (250.0±94.9pg/ml vs. 207.0±86.8pg/ml, P=0.08). However, dippers differed significantly from non-dippers in that they had significantly greater orthostatic heart rate increment (43±16bpm vs. 35±10bpm, P=0.007) and significantly greater orthostatic plasma norepinephrine increase (293±136.6pg/ml vs. 209±91.1pg/ml, P=0.028). Our data indicate that in patients with POTS, a non-dipping blood pressure profile is associated with a reduced orthostatic sympathetic reactivity not accounted for by autonomic neuropathy.
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Figueroa
authors.affiliation: Department of Internal Medicine, Mayo Clinic, Rochester, MN, United States.
authors.forename: Darlene M
authors.initials: DM
authors.lastname: Bott-Kitslaar
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Joaquin A
authors.initials: JA
authors.lastname: Mercado
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, United States.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Basford
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Paola
authors.initials: P
authors.lastname: Sandroni
authors.affiliation: Department of Cardiology, Mayo Clinic, Scottsdale, AZ, United States.
authors.forename: Win-Kuang
authors.initials: WK
authors.lastname: Shen
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: David M
authors.initials: DM
authors.lastname: Sletten
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Tonette L
authors.initials: TL
authors.lastname: Gehrking
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Jade A
authors.initials: JA
authors.lastname: Gehrking
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Low
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, United States. Electronic address: singer.wolfgang@mayo.edu.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Singer
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D054972:Postural Orthostatic Tachycardia Syndrome / Q000503:physiopathology*; D011187:Posture / Q000502:physiology; D012189:Retrospective Studies
chemical_list: D009638:Norepinephrine
keywords: Ambulatory blood pressure; Circadian blood pressure rhythm; Dipping; Orthostatic intolerance; Postural tachycardia syndrome