Reentry in non-uniformly anisotropie ventricular myocardium — Simulation and visualization in a computer model

We tested the hypothesis that non-uni-formly anisotropie coupling combined with variation in recovery properties provides the substrate for reentry by simulating a 22 × 8 mm sheet of myocardium as a grid of 17,600 elements obeying Beeler-Reuter kinetics. Barrier lines of relative transverse uncoupling defined a conducting isthmus. In separate experiments, we varied barrier resistivity, length and width. Membrane ionic properties were uniform throughout, except at the mouth of the isthmus where abnormal recovery properties were specified. We found that regional variation in cellular recovery properties allows for unidirectional block of premature extrastimuli and initiation of reentry, while-transverse uncoupling, when of the proper geometry, allows for perpetuation of tachycardia. Graphical visualization tools were developed to assist in interpreting the large amount of data produced by the computer model.