Electrophysiological basis of the electrocardiogram

The electrocardiogram (ECG) is a very useful tool to investigate the electrical activity of the heart. Electrical activity of cells generates short-circuit currents in the extra-and intracellular environment. According to Ohm’s law such short-circuit currents cause electrical potential differences also in the extracellular environment. Studying these potentials can give important information about the underlying processes.