The shape of the ECG depends on the lead positions but also on the distribution and depression of different cell types their durations and shapes.
We present an interactive program written in JavaScript and WebGL that allows fast simulations of the ECG by solving and displaying the dynamics of cardiac cells in tissue on a web browser. We use physiologically accurate ODE models of cardiac cell of different types that include SA-node, Right and Left Atria, AV-node, Purkinje and Right and Left Ventricular cell with dispersion that accounts for apex to base and epi to endo variations.
The software allows for in real time variations for each cell type and their spatial range so as to identify how the shape of the ECG varies as a function of the cell type, distribution, excitation duration and action potential shape. The propagation of the wave is visualized in real time through all the regions as parameters are keep fixed or varied, modifying the ECG morphology. This is an excellent program to teach students, fellows and the general public, how AND why lead positions and the different cell physiologies in the heart affects the various morphologies of the ECG. The code is able to solve thousands of simulated cells in real time and independent of operating system, so it can run on PCs, laptops, tablets and cellphones. Among the most interesting simulations include investigations in the shapes and durations of the QRS and T waves, different types of LQT, as well as the dynamics of concordant and discordant alternans in tissue and their effect on T-wave alternans and QRS-alternans. Effects of temperature as well as drugs blocking or enhancing certain ion channels can be simulated in all cell types and quantify their effect on the propagating waves and on the ECGs.