Terminating ventricular tachycardia by pacing induced dynamical inhomogeneities in the reentry circuit

Formation of feedback loops of excitation waves (reentrant circuit) around non-conducting ventricular scar tissue is a common cause of lethal cardiac arrhythmias, such as ventricular tachycardia. This is typically treated by rapid stimulation from an implantable device (ICD). However, the mechanisms of reentry termination success and, more importantly, failure, are poorly understood. To study such mechanisms, we simulated pacing of anatomical reentry in an ionic model of cardiac tissue, having significant restitution and dispersion properties. Our results show that rapid pacing causes inhomogeneous conduction in the reentrant circuit, leading to successful pacing termination of tachycardia. The study suggests that more effective pacing algorithms can be designed by taking into account the role of such dynamical inhomogeneities.