[Note: The autonomic nervous system is responsible for maintaining stability of functions such as heart rate/blood pressure in the body - and a part of it, the sympathetic nervous system, becomes more active when the body is stressed by physical or psychological stimuli
The Chronic Fatigue Syndrome (CFS) has been shown to be associated with orthostatic intolerance and cardiovascular dysregulation.
We investigated the cardiovascular responses to combined orthostatic stress and isometric exercise in adolescents with CFS. We included a consecutive sample of 15 adolescents 12 to 18 years old with CFS diagnosed according to a thorough and standardized set of investigations, and a volunteer sample of 56 healthy control subjects of equal sex and age distribution.
Heart rate, systolic, mean and diastolic blood pressure, stroke index, and total peripheral resistance index were non-invasively recorded during lower body negative pressure (LBNP) combined with two consecutive periods of handgrip.
In addition, we measured baseline plasma catecholamines, and recorded symptoms.
At rest, CFS patients had higher heart rate, diastolic blood pressure, plasma norepinephrine (P < 0.01), mean blood pressure and plasma epinephrine (P < 0.05) than controls.
During lower body negative pressure (LBNP), CFS patients had a greater increase in heart rate, diastolic blood pressure, mean blood pressure (P < 0.05) and total peripheral resistance index (n.s.) than controls.
During handgrip, CFS patients had a smaller increase in heart rate, diastolic blood pressure (P < 0.05), mean blood pressure and total peripheral resistance index (n.s.) than controls.
Our results indicate that adolescents with CFS have increased sympathetic activity at rest with exaggerated cardiovascular response to orthostatic stress, but attenuated cardiovascular response when performing isometric exercise during orthostatic stress. This suggests that CFS might be causally related to sympathetic dysfunction.
Source: European Journal of Applied Physiology. Dec 8, 2007 [E-pub ahead of print] PMID: 18066580, by Wyller VB, Saul JP, Walløe L, Thaulow E. Department of Pediatrics, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway.