[Simulation of a one-dimensional impulse transmission along a heart muscle fiber with varied intracellular specific resistance--unidirectional block].

The subject of this study is the modeling of the spread of excitation along a ventricular myocardial fibre based on the one-dimensional "cable" (transmission line) theory. In particular the influence of a varying intracellular c resistivity, R, and of the extracellular potassium concentration [K]o on the propagation is investigated. The membrane model used is the Luo-Rudy model, with which such cellular phenomena as supernormal excitability and Wenckebach pattern can be simulated. The specific resistivity, R, comprises the resistivity of the myoplasm and that of the gap junction. The phenomen of the unidirectional block (UDB) can be simulated in the ischaemic/non-ischaemic transitional zone. Here, the resistivity peak within the ischaemic border zone--caused by collagenous tissue--in combination with a gradient of the R along the fibre-plays a basic role. This simulation study makes it evident that variations in the R-profile have a considerably greater effect on the propagation of a stimulus than variations in the [K]o-profile.