The implementation of element-to-element propagation into the Miller-Geselowitz heart model, so as to automatically generate activation isochrones, is described. This implementation was achieved from initiation sites on the endocardial surface of the model via a Huygens’ construction, utilizing ellipsoidal propagation wavelets to reflect anisotropic propagation in the myocardium. Isochrones similar to those specified for normal activation of the original Miller-Geselowitz model were obtained, using propagation velocities derived from published propagation velocities measured in isolated tissue. Futther validation of the new model was sought by simulating the Wolff-Parkinson-White syndrome, in which preexcitation of the ventricles of the heart occurs due to an accessory pathway connecting atria and ventricles, resulting in an initial delta wave in the QRS complex of the electrocardiogram. The approximate site of the accessory pathway may be deduced from the subject’s body surface potential map pattern during the delta wave, or from the polarities of the delta wave in the 12-lead electrocardiogram, or again from the orientation of the spatial vector-cardiogram during the delta wave. By specifying eight separate accessory pathway initiation sites, followed 40 ms later by normal activation, the isochrones corresponding to preexcitation were simulated. The body surface potential maps, electrocardiograms, and vectorcar-diograms were calculated using an inhomogeneous torso model. Source.