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: Juan J Figueroa, Darlene M Bott-Kitslaar, Joaquin A Mercado, Jeffrey R Basford, Paola Sandroni, Win-Kuang Shen, David M Sletten, Tonette L Gehrking, Jade A Gehrking, Phillip A Low, Wolfgang Singer
• Journal: Autonomic neuroscience : basic & clinical (Auton Neurosci) Vol. 185 Pg. 107-11 (Oct 2014) ISSN: 1872-7484 [Electronic] Netherlands
• PMID: 25033770 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical References

• Norepinephrine

Topics

• Adult
• Blood Pressure (physiology)
• Blood Pressure Monitoring, Ambulatory
• Circadian Rhythm (physiology)
• Female
• Heart Rate (physiology)
• Humans
• Male
• Norepinephrine (blood)
• Postural Orthostatic Tachycardia Syndrome (physiopathology)
• Posture (physiology)
• Retrospective Studies