A logical state model of reentrant ventricular activation

The ventricular surface of the heart was modeled as a two-dimensional, 4096-element network of cells connected logically to each other. An ischemic area was represented by a central core of prolonged refractoriness, distributed into eccentrically layered elliptical contours such that refractoriness declined along varying gradients to the surrounding normal area. Propagation of cardiac action potentials was simulated by five sequential states ranging from activation to inactivation. Reentrant activation was induced by premature stimulation of the network and resembled a figure-eight-type reentry seen experimentally. These simulations indicate that reentrant activation is characterized by the formation of long lines of conduction block which occur along a border of steeply graded refractoriness and by retrograde slow conduction which occurs along a more shallow refractory gradient.