SIMULATION OF ECG FROM 2 PAIRS OF ACTION-POTENTIALS

A simple model for simulation of ECG is presented with the purpose to mimic some common ECG configurations and to generate a hypothesis rega rding their electrophysiological background. Action potentials (AP) we re simulated on a personal computer from ion currents as described pre viously (Wohlfart & Arlock, 1993). The difference between two APs of a pair was used to create an electrogram (EG). The subendocardial AP of the pair was triggered by means of a simulated current injection and the subepicardial AP was triggered from the first AP due to electric c oupling within the pair. The subendocardial APs were of longer duratio n than the epicardial AP because of differences in background currents . A second pair of APs representing another ventricular site was simul ated in an analogous way and this pair was activated somewhat later in time. ECG was calculated as the difference between the two EGs. Right -bundle branch block could be imitated by reducing the coupling betwee n the APs representing the right ventricle. Left-bundle branch block w as generated in an analogous way. ECG in acute myocardial infarction w as created after making one of the epicardial APs ischaemic in appeara nce (reduced amplitude, short duration). Status-post infarction ECG (Q -wave and negative T) was produced by reducing the influence from the EG of the infarcted area. Negative T and increased R-wave as in hypert rophy could also be reproduced. Down sloping ST-segment and negative T as in subendocardial ischaemia was also possible to imitate. The simu lations showed that biphasic T-waves or T and U-waves follows when the two EGs are separated properly in time.