Beat-to-beat monitoring of the sympatho-vagal balance during ischemic episodes

In two groups of patients with Chronic Stable Angina (CSA, 4 patients) and Vasospastic Angina (VA, 6 patients) the authors studied the role of automatic control by frequency analysis of the heart rate variability (HRV) signal via autoregressive (AR) models. The spectral parameters that quantify the sympatho-vagal balance were evaluated on 24 h ECG recordings and in correspondence of ischemic events. Since the HRV signal is not stationary, the AR model was used in its time-variant form in correspondence of ischemic events. The 24th analysis in VA patients evidenced an impaired control by the autonomic nervous system. In correspondence of the ischemic events a sympathetic activation was documented. In CSA episodes the maximum of such an activation was observed after the onset of the event, while in VA patients the sympathetic activation reaches its maximum before the onset of the attack. On the basis of these results a different autonomic involvement can be hypnotized for the two different pathologies.