Analysis of beat-to-beat 24-h α-baroreceptive gain: study of non linear dynamics

Spontaneous changes of ECG and Arterial Blood Pressure (ABP) variability and their interaction can IIC assessed through the baroreceptive α-gain. Quantification of this parameter has been obtained through an automatic spectral technique for ARMA time-variant model applied to HR and ABP variability. Series of beat-to-beat 24h a-gain values in normal subjects have been then analyzed in order to estimate complexity parameters which are indices of chaotic dynamics. Fractal dimension and Ilf slope were calculated during the day and the night hours. Results agree with the hypothesis that chaotic dynamics are involved in cardiovascular variability regulation and especially in a beat-to-beat α gain series.