Assessment of cardiac autonomic state based on RR and QT interval series and symbolic analysis

This paper is aimed to explore the possibility in evaluating the state of cardiac autonomic nerve based on paired short-term heart rate variability (HRV) and QT variability (QTV) indexes. Fantasia Database and Normal Sinus Rhythm Database were used as data source. Using short-term symbolic analysis and mutual information (MI) estimation, the consistency of HRV and QTV and its influencing factors were investigated. The MI of paired HRV and QTV indexes had no significant difference according to age, sex and circadian rhythm, while there were significant differences in most HRV indexes at the same time. The proposed measure is expected to reduce the influence of individual difference and highlight that of some pathological states.