Hemodynamic abnormalities have been documented in the chronic fatigue syndrome (CFS), indicating functional disturbances of the autonomic nervous system responsible for cardiovascular regulation.
The aim of this study was to explore blood pressure variability and closed-loop baroreflex function at rest and during mild orthostatic stress in adolescents with CFS. [Stress on 'automatic' cardiovascular regulation associated with standing upright from a prone position.]
We included a consecutive sample of 14 adolescents 12-18 years old with CFS diagnosed according to a thorough and standardized set of investigations, and 56 healthy control subjects of equal sex and age distribution.
Heart rate and blood pressure were recorded continuously and non-invasively during supine rest and during lower body negative pressure (LBNP) of -20 mmHg to simulate mild orthostatic stress.
Indices of blood pressure variability and baroreflex function (alpha-gain) were computed from monovariate and bivariate spectra in the low-frequency (LF) band (0.04-0.15 Hz) and the high-frequency (HF) band (0.15-0.50 Hz), using an autoregressive algorithm.
Variability of systolic blood pressure [pressure when the heart is contracting] in the HF range was lower among CFS patients as compared to controls both at rest and during LBNP.
During LBNP, compared to controls, alpha-gain HF decreased more, and alpha-gain LF and the ratio of alpha-gain LF/alpha-gain HF increased more in CFS patients, all suggesting greater shift from parasympathetic to sympathetic baroreflex control.
CFS in adolescents is characterized by reduced systolic blood pressure variability and a sympathetic predominance of baroreflex heart rate control during orthostatic stress.
These findings may have implications for the pathophysiology of CFS in adolescents.
Source: European Journal of Applied Physiology, Oct 2, 2010. PMID: 20890710, by Wyller VB, Barbieri R, Saul JP. Department of Pediatrics, Rikshospitalet University Hospital, Oslo, Norway. [Email: firstname.lastname@example.org]