Background: Although it is assumed that cerebral oxygenation during exercise is influenced by both cardiopulmonary function and cerebrovascular arteriosclerosis, the latter factor has not been fully clarified. In the present study the relationship between the degree of cerebrovascular arteriosclerosis and cerebral oxygenation during exercise was investigated.
Methods and results: A total of 109 patients (69 patients with coronary artery disease, 40 patients with hypertensive heart disease) (61.7+/-9.7 years) performed a symptom-limited exercise test with respiratory gas measurements (CPX). From the respiratory gas analysis, peak O(2) uptake (VO(2)), the slope of the increase in VO(2) to the increase in work rate (DeltaVO (2)/DeltaWR), and the slope of the increase in ventilation to the increase in CO(2) output (VE/VCO(2) slope) were calculated. Oxyhemoglobin (O(2)Hb) at the forehead was monitored using near-infrared spectroscopy. The brain ischemic score was counted based upon fluid-attenuated inversion recovery images of magnetic resonance imaging and expressed from 0 to 4. When compared with patients with a lower ischemic score (<2, n=67), those with a higher ischemic score (> or =2, n=42) had a lower increase in brain O(2)Hb during exercise (-1.08 +/-2.7 vs 0.77+/-4.1 micromol/L, p=0.011). Of brain ischemic score, left ventricular ejection fraction, peak VO(2), DeltaVO(2)/DeltaWR, and the VE/VCO(2) slope, DeltaVO(2)/ DeltaWR was found to be the sole independent index determining cerebral O(2)Hb during exercise. The CPX parameters were also significantly related to the degree of cerebrovascular arteriosclerosis.
Conclusions: Although cerebral oxygenation during exercise is mainly related to cardiopulmonary function, the degree of cerebrovascular arteriosclerosis partly influences cerebral oxygenation in patients with risk factors for atherosclerosis.