Date sent:      	Sat, 5 Jan 2002 

Source: http://www.ahmf.org/01behan3.html
The Third International Clinical and Scientific Meeting


Cardiovascular function and exercise intolerance in
chronic fatigue syndrome

WMH Behan, E Georgiades, Y Pitsiladis, N Macfarlane, J
Wilson, L Kilduff & SA Ward

Department of Pathology and Centre for Exercise Science
and Medicine,
Glasgow University,
Glasgow,
Scotland,
UK

Correspondence to:
Professor WMH Behan,
Department of Pathology,
Western Infirmary,
Glasgow G11 6NT
Telephone: +44 141 211 2208
Email:wmb1q@clinmed.gla.ac.uk



Chronic fatigue syndrome (CFS) is characterised by impaired
skeletal muscle function, with consequent impairment of
exercise tolerance. Little attention, however, has been given
to the contribution of cardiovascular dysfunction to this
impaired exercise capacity.


Seven patients with CFS (age 35 + 7 yr, SD) therefore
performed cardiopulmonary exercise testing on different
occasions, utilising (a) ramp-incremental cycle-ergometer
exercise to the limit of tolerance and (b) moderate (i.e.
below the lactate threshold) constant-load.


Subjects demonstrated resting pulmonary function that was
within normal limits (FEV1/FVC = 0.78 ± 0.05). Evidence of
exercise intolerance was found in the reduced peak oxygen
uptake (1.48 ± 0.41 l/min, 71% predicted) on the
ramp exercise test, with maximum levels of perceived leg
fatigue being attained. There was a modest reduction in both
peak heart rate (HR) (164 ± 31 bt/min; 89 ± 11 % pred)
and oxygen pulse (8.9 ± 1.6 ml/bt; 80 ± 11 %
pred). Further evidence consistent with cardiovascular
dysfunction was that cardiac output (estimated by the CO2
rebreathing technique) during moderate exercise was below
predicted in 4 of the 7 patients (although normal, or even
high, in 2, with valid measurements not being obtained in one
patient).


These results therefore, provide preliminary evidence of
cardiovascular impairment during dynamic exercise in
patients with CFS, as judged by the cardiac output response
to moderate exercise. However, as is the case with other
"markers" of functional impairment in this patient population,
there was considerable heterogeneity in its degree.


Acknowledgements: This work was supported by the Barclay
Trust & the Myalgic Encephalomyelitis Association.