Threshold based acceleration change index (TACI) for heart rate variability analysis

Heart role variability (HRV) analysis is a useful diagnostic tool for autonomic nervous balance assessment. In this paper, we have proposed threshold based acceleration change index (TACI), for HRV analysis, which is closely related to the acceleration change index (ACI). ACI index characterizes the sign of difference of time series, whereas, for TACI computation, we relate the sign of difference of the time series with some threshold value. ACI is the special case of TACl, when threshold value is zero. If was found that TACl is more robust in classifying various groups under different physiological and pathological conditions. In this paper the performance of TACl is evaluated for classifying following groups and conditions retrospectively: (a) healthy subjects versus those with congestive heart failure (CHF); (b) young and elderly healthy subjects; (c) Young healthy subjects versus arrhythmia patient.