Chronic fatigue syndrome: illness severity, sedentary lifestyle, blood volume and evidence of diminished cardiac function.
This study examined whether deficits in cardiac output and blood volume in a Chronic Fatigue Syndrome (CFS) cohort were present and linked to illness severity and sedentary lifestyle. Follow-up analyses assessed whether differences between CFS and control groups in cardiac output levels were corrected by controlling for cardiac contractility and total blood volume (TBV). The 146 participants were subdivided into two CFS groups based on symptom severity data, severe (n=30) vs. non-severe (n=26), and two healthy non-CFS control groups based on physical activity, sedentary (n=58) vs. non-sedentary (n=32). Controls were matched to CFS participants using age, sex, ethnicity and body mass. Echocardiographic measures indicated that the severe CFS participants displayed 10.2% lower cardiac volume (i.e., stroke index and end diastolic volume) and 25.1% lower contractility (velocity of circumferential shortening corrected by heart rate) than the control groups. Dual tag blood volume assessments indicated that CFS groups had lower TBV, plasma volume (PV) and red blood cell volume (RBCV) than control groups. Of the CFS subjects with a TBV deficit (i.e., >/=8% below ideal levels), the mean +/-SD percent deficit in TBV, PV and RBCV were 15.4+/-4.0, 13.2+/-5.0, and 19.1+/-6.3, respectively. Lower CFS cardiac volume levels were substantially corrected by controlling for prevailing TBV deficits, but were not affected by controlling for cardiac contractility. Analyses indicated that the TBV deficit explained 91-94% of the group differences in cardiac volume indices. Group differences in cardiac structure were offsetting and hence no differences emerged for LV mass index. Therefore, the findings indicate that lower cardiac volume levels, displayed primarily by persons with severe-CFS, were not linked to diminished cardiac contractility levels, but were likely a consequence of a comorbid hypovolemic condition. Further study is needed to address the extent to which the CFS cardiac and blood volume alterations have physiological and clinical significance.
PMID: 19469714 [PubMed - as supplied by publisher]
