Numerical analysis of Conduction of the action potential across the Purkinje fibre-ventricular muscle junction

Normally, there is little conduction delay ( 2 /ms for the Purkinje fibreand ventricular muscle to give expected conduction velocities. The effects of (i) the diffusion coefficients between the terminal Purkinje celland the transitional cell (D1) and between the transitional cell and the first ventricular myocyte(D2) and (ii) the ‘load’ on the Purkinje fibre(i.e. number of strings of ventricular myocytes) were investigated. The greater D1 (up to ∼0.4 mm 2 /ms), the larger the load that could be supported, although further increase in D1 resulted in little further increase. Also the greater D2 (up to ∼0.04 mm 2 /ms), the larger the load that could be supported, but in this case a further increase in D2 resulted in a decrease in the load that could be supported. The delay in conduction at the PVJ was dependent on D1, D2 and load and increased markedly at the smallest values of D1 and D2 and the highest loads. At a certain point, a small change could lead to large increase in the delay or even conduction failure.