In a computer model of rabbit ventricles, increasing Purkinje-Myocyte Junction density increased the mean firing rate in the Purkinje system and epicardial wave breaks, but densities above 13/cm2 did not alter reentry dynamics.
The Purkinje system is the fast conduction network of the heart which couples to the myocardium at discrete sites called Purkinje-Myocyte Junctions (PMJs). However, the distribution and number of PMJs remains elusive, as does whether a particular PMJ is functional. We hypothesized that the Purkinje system plays a role during reentry and that the number of functional PMJs affect reentry dynamics. We used a computer finite element model of rabbit ventricles in which we varied the number of PMJs. Sustained, complex reentry was induced by applying an electric shock and the role of the Purkinje system in maintaining the arrhythmia was assessed by analyzing phase singularities, frequency of activation, and bidirectional propagation at PMJs. For larger junctional resistances, increasing PMJ density increased the mean firing rate in the Purkinje system, the percentage of successful retrograde conduction at PMJs, and the incidence of wave break on the epicardium. However, the mean firing of the ventricles was not affected. Furthermore, increasing PMJ density above 13/Formula: see text did not alter reentry dynamics. For lower junctional resistances, the trend was not as clear. We conclude that Purkinje system topology affects reentry dynamics and conditions which alter PMJ density can alter reentry dynamics.
Behradfar et al. (Fri,) conducted a other in Ventricular Arrhythmia. Varying Purkinje-Myocyte Junction (PMJ) density vs. Different PMJ densities was evaluated on Reentry dynamics (mean firing rate, wave break incidence, bidirectional propagation). In a computer model of rabbit ventricles, increasing Purkinje-Myocyte Junction density increased the mean firing rate in the Purkinje system and epicardial wave breaks, but densities above 13/cm2 did not alter reentry dynamics.