Linear and nonlinear characteristics of ECG signals produced by simulations of ventricular tachyarrhythmias

The aim of this study was to compare pseudo-ECGs produced by different configurations of re-entry in a computational model. We initiated single, double and multiple re-entrant waves in a cuboid with Fitz-Hugh Nagumo excitability. We estimated one component of the pseudo-ECG, and applied linear time-frequency and nonlinear dimensional analysis. The pseudo-ECG produced by a single re-entrant wave was periodic, whereas that produced by a double re-entrant wave was quasiperiodic with slow changes in both frequency content and amplitude. The dimension of these time series was around 1 and 3 respectively. The time-frequency distribution of the pseudo-ECG produced by multiple re-entrant waves was more complex with rapid changes in frequency and amplitude, and the dimension of the pseudo-ECG time series was around 4. Thus different configurations of reentrant wave are associated with qualitatively and quantitatively different pseudo-ECG time series.