Spectral analysis of r-r and arterial pressure variabilities to assess sympatho-vagal interaction during mental stress in humans

We tested the hypothesis that spectral analysis of the R-R in-terval and systolic arterial pressure variabilities allows assess-ment of the dynamic changes in neural control of the cardio-vascular system in men undergoing mental stress testing. Mental arithmetic increased the low-frequency components of R-R and systolic arterial pressure, i.e. markers of sympathetic activity to the SA node and the vasculature, respectively; it also decreased the high frequency component of R-R variability, a marker of vagal activity. Spectral analysis of R-R and systolic arterial pressure variabilities may be used in the clinic to test the dynamic effects of mental stress on both sympathetic and vagal activities.