Effect of Lower Limb Venous Dilation on the Autonomic Cardiac Response among Healthy Young Men.

Venous occlusion of the lower limbs, which simulates edema, can alter heart rate variability (HRV) by increasing feedback information from group III/IV sensory fibers. Our aim was to quantify this effect among healthy young men. The study group included 13 men (mean age, 20.4 years). Venous occlusion of the lower limbs was induced using a pressure cuff around both thighs. The effect of occlusion on autonomic cardiac response was quantified under occlusion pressures of 20, 60, and 100 mmHg. Compression was applied for 5 min. HRV was evaluated from changes in the low-frequency (LF) and high-frequency (HF) power of the electrocardiogram and the resulting LF/HF balance. Near-infrared spectroscopy of the leg was used to quantify the effects of occlusion on deoxyhemoglobin, measured as the area under the curve (HHb-AUC). The occlusion pressure of 100 mmHg induced a significant increase in the LF/HF ratio, compared to the baseline ( < 0.05). HHb-AUC was highest for the 100 mmHg occlusion pressure compared with the 20 and 60 mmHg pressures ( < 0.01). These findings indicate that venous dilation may elicit a shift towards sympathetic dominance in the autonomic balance.