A novel mathematical model of the electrical action potential in a canine Purkinje fiber cell

Purkinje fiber (PF) cells exhibit action potential (AP) morphology and duration markedly different to those of ventricle myocytes. In order to study heterogeneity at the Purkinje-ventricular junction (PVJ), we construct a new AP model for the canine PF cell based on detailed experimental data of ion channel characteristics obtained by voltage clamp techniques. Single-cell PF model is incorporated into a 1D transmural strand model, which is used to simulate the AP conduction through the PVJ under physiological and short QT syndrome (SQTS) conditions. Simulations produced the APD dispersion patterns and pseudo-ECGs consistent with experimental data under physiological conditions. Incorporating changes to the activation kinetics and time constants of the IKs channel associated with the KCNQ1 gene mutation resulted in the shortened QT interval characteristic of SQTS.