Simulation studies of the electrocardiogram. I. The normal heart.

Abstract

A digital computer model is presented for the simulation of the body surface electrocardiogram (ECG) during ventricular activation and recovery. The ventricles of the heart are represented in detail by a three-dimensional array of approximately 4000 points which is subdivided into 23 regions. Excitation sequence and cellular action potential data taken from the literature are used to determine the spatial distribution of intracellular potentials at each instant of time during a simulated cardiac cycle. The moment of the single dipole representing each region is determined by summing the spatial gradient of the intracellular potential distribution throughout the region. The resulting set of 23 dipoles is then used to calculate the potentials on the surface of a bounded homogeneous volume conductor with the shape of an adult torso. Simulated isopotential surface maps during both activation and recovery are in good agreement with data for humans reported in the literature.

Quantitative Prediction of Body Surface Potentials from Myocardial Action Potentials Using a Summed Dipole Model

“…Most closely matching the objectives of the present paper was the work of Miller and Geselowitz 10 in 1978. They assumed that a net current flows in an intracellular network from regions of higher intracellular potentials to regions of lower intracellular potentials.…”

“…The extensive development of numerical methods and computer hardware has made the study of very complex models possible, including detailed models of cardiac muscle cells and ion channels, cardiac and non-cardiac tissues (biodomains), and the three dimensional gross anatomy of the thorax 2 . Notable examples of complex solutions to the forward problem include those of Plonsey 3 , Geselowitz 4 , Rudy 5 , Gulrajani 6 , Selvester 7 , Barr 8 , Gelernter and Swihart 9 (1964), and Miller and Geselowitz 10 . While technically successful, these mathematical models are exceedingly complex and far beyond the understanding of most students of physiology and medicine.…”

Effect of tissue anisotropy on extracellular potential fields in canine myocardium in situ.

“…Equation 17 is a general expression for the extracellular potential <P,, in terms of spatial derivatives of the transmembrane potential. Again, it is clear that there can be no extracellular electric field unless the spatial gradient of the transmembrane potential is nonzero; this is also true for isotropic tissue (Miller and Geselowitz, 1978).…”

“…Our basic tissue model (Roberts et al, 1979) extends to anisotropic myocardium a model that has been used previously for isotropic tissue (Miller and Geselowitz, 1978). Our model consists of two parallel, continuous, anisotropic, conducting media, the intracellular (i) and extracellular (o) media, connected at each point in space by the cell membrane.…”

Approche multi-échelle appliqué à la modélisation de l’activité électrique du coeur

“…Les résultats de simulation suggèrent que la dispersion spatiale des propriétés de repolarisation doit être plus grande que celle qui est observée dans des cellules isolées. C'est une faiblesse car, en contrepartie, l'ECG simulé par les modèles les plus avancés semble pour le moment moins réaliste que celui que produisent des modèles plus anciens ou plus simples [27] où les sources utilisées pour reproduire un ECG normal sont déterminées empiriquement plus qu'elle ne se fondent directement sur des données expérimentales. Le but ultime est de disposer d'un modèle coeur-torse réaliste ( Figure 5) qui puisse être adapté à chaque patient pour valider le diagnostic établi à partir de l'ECG ou guider la thérapie, comme le choix du site d'implantation des électrodes des stimulateurs cardiaques.…”