Heart period dynamics following an asphyxia experiment in rats

The present work proposes an optimal symbol dynamics transformation as an approach to analyze dynamic aspects of heart rate variability (HRV) in an asphyxia experiment in rats. The approximate entropy (ApEn) was used to quantify the regularity of short symbolic sequences derived from 5 min R-R intervals (RRI). The comparison of several symbol transformations applied in HRV analysis indicates our approach as optimal for characterizing the transitions between different phases in the recovery process following asphyxia in rats.