This study examined the cardiovascular response to orthostatic
challenge, and incidence and mechanisms of neurally mediated
hypotension in chronic fatigue syndrome (CFS) during a head-up
tilt test. Stoke volume was obtained by a thoracic impedance
cardiograph, and continuous heart rate and blood pressure were
recorded during a 45-min 70 degrees head-up tilt test.
Thirty-nine CFS patients and 31 healthy physically inactive
control subjects were studied. A positive tilt, i.e. a drop in
systolic blood pressure of > 25 mmHg, no concurrent increase
in heart rate and/or development of presyncopal symptoms, was
seen in 11 CFS patients and 12 control subjects (P > 0.05).
During baseline and the first 5 min of head-up tilt, CFS
patients had higher heart rate and smaller pulsatile-systolic
area than control subjects (P < 0.05). Among subjects who
completed the test, those with CFS had higher heart rate and
smaller stroke volume (P < 0.05) than corresponding control
subjects. When comparing those who had a positive test outcome
in each group, CFS patients had higher heart rates and lower
pulse pressure and pulsatile-systolic areas during the last 4
min before being returned to supine (P < 0.05). These data
show that there are baseline differences in the cardiovascular
profiles of CFS patients when compared with control subjects
and that this profile is maintained during head-up tilt.
However, the frequency of positive tilts and the haemodynamic
adjustments made to this orthostatic challenge are not
different between groups.
LaManca JJ, Peckerman A, Walker J, Kesil W, Cook S, Taylor A,