Effect of Cell Geometry on Conduction Velocity in a Subcellular Model of Myocardium

We have studied the effect of cell geometry on propagation velocity of the cardiac impulse using a subcellular computer model of myocardium. Variation of cell size has only small effects on longitudinal and transverse conduction velocities, when the ratio of cell length/width is constant, for cell sizes (length X width) between (60 μm × 20 μm) and (120 μm × 40 μm). The results were not dependent on gap-junction conductance (range 0.25-1 μS), gap-junction distribution, or the specific tissue architecture. Longitudinal conduction velocity increased with the cell length/width ratio and transverse velocity decreased. The cell length/width ratio was a good estimator of the anisotropic ratio. In conclusion, cell length/width ratio is more important than cell size in determining conduction velocity.