ECG-oesophageal recording for beat-to-beat analysis of A-V conduction time variability

Oesophageal recording and spectral analysis were used to investigate the atrioventricular conduction (AVC) time variability. Ten minutes of surface electrocardiogram (ECG) and oesophageal electrogram were recorded from seven healthy subjects. With an automatic procedure A-wave and R-wave fiducial points were measured respectively on the oesophageal and surface ECG. The A-A and A-R intervals series were described in the time domain by computing mean and standard deviation. Frequency analysis was performed by applying an autoregressive power spectra density (PSD) estimation. Both A-R and A-A PSD show the characteristic frequency distribution mainly concentrated in low (LF) and high (HF) frequency bands. Nevertheless, greater activity around the HF component in the A-R spectra was found. These findings suggest the presence of a direct influence of the autonomic nervous system (ANS) on A-V conduction.