Time-variant autoregressive spectral estimation in acute ischemic episodes

Time-invariant algorithms of autoregressive spectral estimation were employed in the study of the heart rate variability signal to quantify, on a beat-by-beat basis, the effect of the sympatho-vagal balance in the assessment of the heart rate. Thus, it was possible to obtain the relevant spectral parameters during transient phenomena, in which the hypotheses of stationarity, required for a batch analysis, are not respected. In particular, the focus is on the study of the cardiac transient ischemic pathology, aiming at analyzing the dynamical changes corresponding to the beginning of the attack and during the attack itself. For this purpose, the European ST-T database provides a significant number of cases of ischemic attacks that have been studied through time-invariant spectral analysis for a better comprehension of the origin mechanisms and of the involvement of the autonomic nervous system in the ischemic episodes