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A new, fast, and robust index for heart rate variability analysis

The acceleration change index (ACI) to describe heart rate variability (HRV) is presented. It is calculated from the parameters of a time series derived from the RR time series. Evaluating the ACI for simulated signals shows that it correlates with the their fractal dimension. Evaluating the ACI for records from healthy subjects shows that it decreases with periodical breathing and increases during exercise. When the ACI is applied to records from commercial ECG databases, it can discriminate healthy subjects from subjects who had suffered ventricular tachycardia and/or fibrillation and from subjects with myocardial ischemia.