Analysis of heart rate changes associated with ictal activity

The authors examined the EKG signal and its relationship to seizure activity. The EKG data was divided into three periods: before, during and after ictal activity based on visual and behavior classification of the data. Traditional indices, such as the mean and variance, of the R-R intervals of heart beats are evaluated to compare the variation in these three periods. The spectra of the R-R intervals are investigated to determine a ratio between the highest variation (HV) and the lowest variation (LV). This ratio shows how fast the R-R Intervals change during these three periods. Nonlinear time-frequency analysis is also used to evaluate heart rate changes before and after ictal activity. The time-frequency analysis shows that the heart rate increases during the an ictal event and decreases back towards a normal range after the ictus