A model for simulating Bundle Branch and Fascicular Block

The objective of this paper is to develop a model for simulation of bundle branch and fascicular block. The model accounts for the contribution of fiber orientation to the velocity of signal propagation through the myocardium as well as "reentry " of the signal into the subendocardial purkinje system. The Selvester/Soloman method for simulation of normal myocardial activation was adapted to the ECG-TECH Heart-to-loop-to leads software .The software connects the intercardiac activation to the body surface vector and ECG recordings and was modified for this study to simulate complete right and left bundle branch and left anterior and left posterior fascicular block. The process of developing models that simulated typical recorded QRS waveforms of these four conduction abnormalities involved iterative interaction among the investigators. Accurate simulations of each of these inter ventricular conduction abnormalities was accomplished by utilizing published data on the purkinje and myocardial conduction properties, especially at the purkinje myocardial junction. Agreement between the simulated and recorded waveforms was accomplished by varying 1) the locations of the initial purkinje-myocardial activation sites and 2) the relative contributions of intra-myocardial conduction and reentry to the subendocardial purkinje system to activation of myocardium past the point of conduction block. Conclusions: Accurate simulation of intraventricular conduction abnormalities caused by bundle branch and fascicular block abnormalities was accomplished. These results were then used to add conduction defects to the 3D heart training program used to train medical students to better diagnose heart disease.