Activation delay in bifurcating strands of surviving myocardial tissue in healed infarction - a comparison between model and experiment. Maglaveras, Nicos, Jacques M. T. De Bakker, Frans J. L. Van Capelle, Costas Pappas, Michiel J. Janse. Laboratory of Medical Informatics, The Medical School, Aristotelian University, Thessaloniki, Macedonia, Greece, Department of Clinical and Experimental Cardiology, University of Amsterdam, Academic Medical Center, Amsterdam and the Interuniversity Cardiology Institute, The Netherlands
APStracts 2:0233H, 1995.
Conduction delay in healed myocardial infarction, facilitating reentry, is frequently based on an increase of the route activation has to travel in a matrix of merging and diverging bundles that survive in the infarcted area. Additional delay occurs at sites where bundles bifurcate. The purpose of this study was to investigate conduction delay at sites where bundles bifurcate. A computer model was dveloped to simulate spread of activation in a 2-dimensional sheet of excitable elements. A structure consisting of 2 isolated bundles merging into a single one was modelled. Extracellular electrograms calculated in the model were comparable to electrograms obtained in a superfused infarcted papillary muscle model. A zone of crowded isochrones or local conduction delay was found at the site where an isolated bundle bifurcated. The position of the isochrones in this area depended on the way activation times were determined. Lines of activation delay were mainly perpendicular to the fiber direction. In conclusion, the results have enabled us to better understand extracellular electrograms at pivoting points and shows that activation sequences at a microscopic level can best be constructed on the basis of Laplacian signals. 

Received 28 June 1994; accepted in final form 4 May 1995.
APS Manuscript Number H565-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  6 July 1995.