Cell2ECG: A virtual laboratory to simulate cardiac electrograms

Engineering approaches to indentify and reverse electrical instabilities of the injured heart have lead to innovative diagnostic and therapeutic solutions. Therefore, curricula of Biomedical Engineering (BME) courses include cardiac electrophysiology. This paper describes a virtual laboratory designed for the study of the generation of the electrocardiogram (ECG) based on cellular electrophysiology. In detail, the virtual lab includes (1) an equivalent source model for cardiac cells, (2) a formulation of the mathematical relationship between the transmembrane potential and the transmembrane current, (3) the determination of resulting extracellular potentials, and (4) the calculation of the ECG by a weighted summation of transmembrane currents. Since these tasks require specific presumption and knowledge concerning cardiac geometry, a geometrical model was constructed using anatomical stylized segments of the left ventricle. Propagation parameters control the activation sequence as well as velocity and direction for anisotropic conduction. In order to verify the developed models and algorithms simulation results were compared against experimentally obtained data under various physiological conditions. Although there is considerable scatter in the measurements, the comparison indicates that a definite relationship exists between measured and computed waveforms. Simulations interactively show physiological and pathophysiological changes in the ECGs for various user setting of the cell function. In conclusion, the interactive laboratory enables the user to study the relationship between the electric activity of cardiac cells and the resulting extracellular potentials including the ECGs on the body surface. Students increase their knowledge of cardiac electrophysiology, applied electrical circuit theory and the understanding of differential equations as well as numerical methods for solving them.