Re-entry by early afterdepolarisations in a computational model

Afterdepolarisations are one mechanism suggested for the spontaneous initiation of re-entrant arrhythmias in the ventricles but are difficult to study experimentally. We have conducted a systematic investigation of the initiation of reentry by afterdepolarisations using a computational model of cardiac ventricular tissue. We implemented a mono- domain model of a ID fibre, where the excitability of the cell membrane was described by the 4 variable Fenton-Karma (FK4V) model. We embedded additional behaviour into the FK4V model, so a prescribed region produced afterdepolarisations. By changing the size of this region, and duration, amplitude and frequency of the afterdepolarisation potentials, we were able to look in detail at how after- depolarizations can initiate propagating action potentials. This study has shown that afterdepolarisations are capable of producing re-entry, but the duration and amplitude of the afterdepolarisation potential are important in determining whether re-entry is produced.