[Calf flow reserve measured by venous-occlusion near-infrared spectroscopy: relationship to exercise tolerance]

The correlations between calf flow reserve evaluated with venous-occlusion near-infrared spectroscopy, air plethysmography or skin laser Doppler flowmetry were investigated in patients with cardiovascular diseases. The relationships to exercise tolerance during upright bicycle exercise were also examined.

The calf flow reserve (blood flow after 5 min of arterial occlusion/basal blood flow) evaluated by the above three methods and peak oxygen uptake (peak VO2) on bicycle exercise were measured in 24 male patients (mean age 65.0 +/- 7.7 years, left ventricular ejection fraction 24-86%).

There was a good correlation between flow reserve by near-infrared spectroscopy (8.0 +/- 3.8) and air plethysmography (7.9 +/- 3.1; r = 0.90). However, there was a weak correlation between flow reserve by near-infrared spectroscopy and skin laser Doppler flowmetry (3.4 +/- 1.7; r = 0.42). There was a good correlation between flow reserve by near-infrared spectroscopy and peak VO2 (r = 0.69), or flow reserve by air plethysmography and peak VO2 (r = 0.53). However, there was no significant correlation between flow reserve by skin laser Doppler flowmetry and peak VO2 (r = 0.18).

Calf flow reserve evaluated by venous-occlusion near-infrared spectroscopy relates to the flow reserve in the muscle tissue and is minimally affected by the flow reserve in the skin. The flow reserve in the muscle tissue is related to exercise tolerance, but the flow reserve in the skin is not, in patients with cardiovascular diseases.