A comprehensive PC solution to heart rate variability analysis in mental stress

To assess the modifications of the sympathovagal balance induced by mental stress, a computerized system has been developed which is able to carry out a complete spectral analysis of the heart rate variability (HRV) signal. Based on a personal computer, it acquires ECG (electrocardiography), respiratory, and blood pressure signals for each step of a mental stress trial. The collected data are then processed and spectral analysis is carried out by conventional FFT. In addition, an autoregressive identification algorithm computes the power and central frequency of the spectra peaks, allowing automatic classification of low-frequency (LF) and high-frequency (HF) peaks. The analysis executed for each step of the trial allows the comparison of the various spectral responses corresponding to different stimulations. This system was tested on 32 recently infarcted subjects and results show a significant increment in LF peak (P<0.005) and a significant reduction in HF peak (P<0.05) during a mental arithmetic task. Preliminary results suggest that this method can be considered a useful technique for evaluating the autonomic response to mental stress