Central haemodynamic variability during sleep in subjects with and without atrial fibrillation

The aim of this study was to develop a Matlab programme for quantitative evaluation and graphical presentation of haemodynamic variability parameters calculated from electrocardiography (ECG) and impedance cardiography (ICG) signals. We also sought to identify and compare patterns of variability in healthy subjects (N) and subjects with atrial fibrillation (AF). We analysed 3000 seconds of ECG and ICG signals acquired continuously during overnight, home recordings of six healthy male subjects (20–22, group N) and five male patients with atrial fibrillation (ages 56–78, group AF). Haemodynamic variability was determined using standard deviation and indices describing asymmetry of stroke volume, systolic time intervals (STI), and their derivatives. Stroke volume (SV), amplitude of impedance signal (dz/dtmax), ejection time (ET) and pre-ejection period (PEP) were calculated automatically. The standard deviation (SD) of SV varied in the range of 9–16 ml in normal subjects, versus 12–39 ml in AF subjects. SD for ET was 14–42 ms for N and 31–68 ms for AF. PEP SD varied 8–33 ms for N and 12–38 ms for AF. Preliminary results show that the patterns of haemodynamic variability in AF patients differed from those observed in non-patients for most of the analysed indices.