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Auton Neurosci. 2014 Oct;185:107-11. doi: 10.1016/j.autneu.2014.06.003. Epub 2014 Jun 21.

Decreased orthostatic adrenergic reactivity in non-dipping postural tachycardia syndrome.

Author information

1
Department of Neurology, Mayo Clinic, Rochester, MN, United States.
2
Department of Internal Medicine, Mayo Clinic, Rochester, MN, United States.
3
Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, United States.
4
Department of Cardiology, Mayo Clinic, Scottsdale, AZ, United States.
5
Department of Neurology, Mayo Clinic, Rochester, MN, United States. Electronic address: singer.wolfgang@mayo.edu.

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.

KEYWORDS:

Ambulatory blood pressure; Circadian blood pressure rhythm; Dipping; Orthostatic intolerance; Postural tachycardia syndrome

PMID:
25033770
PMCID:
PMC4165658
DOI:
10.1016/j.autneu.2014.06.003
[Indexed for MEDLINE]
Free PMC Article

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