Limits...
Blood pressure variability and closed-loop baroreflex assessment in adolescent chronic fatigue syndrome during supine rest and orthostatic stress.

Wyller VB, Barbieri R, Saul JP - Eur. J. Appl. Physiol. (2010)

Bottom Line: Indices of blood pressure variability and baroreflex function (α-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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Rikshospitalet University Hospital, 0027, Oslo, Norway. brwylle@online.no

ABSTRACT
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. 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 (α-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 in the HF range was lower among CFS patients as compared to controls both at rest and during LBNP. During LBNP, compared to controls, α-gain HF decreased more, and α-gain LF and the ratio of α-gain LF/α-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.

Show MeSH

Related in: MedlinePlus

Individual univariate and bivariate spectra from one healthy control (upper panels) and one CFS patient (lower panels) at baseline (left) and during LBNP (right). Dark shadowed areas indicate the low-frequency range (0.04–0.15 Hz); light shadowed areas indicate the high-frequency range (0.1–0.50 Hz). Vertical dotted lines mark the point of maximal coherence within each frequency band. Of note, in the healthy control, LBNP results in a reduction of α-gain in both frequency bands, whereas in the CFS patient, LBNP is associated with a decrease of HF α-gain and an increase in LF α-gain
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3037975&req=5

Fig1: Individual univariate and bivariate spectra from one healthy control (upper panels) and one CFS patient (lower panels) at baseline (left) and during LBNP (right). Dark shadowed areas indicate the low-frequency range (0.04–0.15 Hz); light shadowed areas indicate the high-frequency range (0.1–0.50 Hz). Vertical dotted lines mark the point of maximal coherence within each frequency band. Of note, in the healthy control, LBNP results in a reduction of α-gain in both frequency bands, whereas in the CFS patient, LBNP is associated with a decrease of HF α-gain and an increase in LF α-gain

Mentions: Gain and phase values were extracted in the low-frequency (LF) band (0.04–0.15 Hz) and the high-frequency (HF) band (0.15–0.5 Hz), anywhere the coherence between RRI and SBP signals reached its maximum inside each frequency band (Fig. 1). As previously suggested, the α-gain for baroreflex feedback was characterized between SBP and RR, and the β-gain feedforward was characterized between RR and DBP because of the direct effects of changes in the RR interval on DBP (Barbieri et al. 2001). For subjects with two experimental recordings, the arithmetical mean for each variable was computed from corresponding experimental epochs.Fig. 1


Blood pressure variability and closed-loop baroreflex assessment in adolescent chronic fatigue syndrome during supine rest and orthostatic stress.

Wyller VB, Barbieri R, Saul JP - Eur. J. Appl. Physiol. (2010)

Individual univariate and bivariate spectra from one healthy control (upper panels) and one CFS patient (lower panels) at baseline (left) and during LBNP (right). Dark shadowed areas indicate the low-frequency range (0.04–0.15 Hz); light shadowed areas indicate the high-frequency range (0.1–0.50 Hz). Vertical dotted lines mark the point of maximal coherence within each frequency band. Of note, in the healthy control, LBNP results in a reduction of α-gain in both frequency bands, whereas in the CFS patient, LBNP is associated with a decrease of HF α-gain and an increase in LF α-gain
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037975&req=5

Fig1: Individual univariate and bivariate spectra from one healthy control (upper panels) and one CFS patient (lower panels) at baseline (left) and during LBNP (right). Dark shadowed areas indicate the low-frequency range (0.04–0.15 Hz); light shadowed areas indicate the high-frequency range (0.1–0.50 Hz). Vertical dotted lines mark the point of maximal coherence within each frequency band. Of note, in the healthy control, LBNP results in a reduction of α-gain in both frequency bands, whereas in the CFS patient, LBNP is associated with a decrease of HF α-gain and an increase in LF α-gain
Mentions: Gain and phase values were extracted in the low-frequency (LF) band (0.04–0.15 Hz) and the high-frequency (HF) band (0.15–0.5 Hz), anywhere the coherence between RRI and SBP signals reached its maximum inside each frequency band (Fig. 1). As previously suggested, the α-gain for baroreflex feedback was characterized between SBP and RR, and the β-gain feedforward was characterized between RR and DBP because of the direct effects of changes in the RR interval on DBP (Barbieri et al. 2001). For subjects with two experimental recordings, the arithmetical mean for each variable was computed from corresponding experimental epochs.Fig. 1

Bottom Line: Indices of blood pressure variability and baroreflex function (α-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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Rikshospitalet University Hospital, 0027, Oslo, Norway. brwylle@online.no

ABSTRACT
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. 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 (α-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 in the HF range was lower among CFS patients as compared to controls both at rest and during LBNP. During LBNP, compared to controls, α-gain HF decreased more, and α-gain LF and the ratio of α-gain LF/α-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.

Show MeSH
Related in: MedlinePlus