Cardiac potential mapping

The purpose of clinical electrocardiography is to interpret the cardiac electrical signals in terms of intracardiac electrophysiological events. To understand the relationships between ECG signals and intracardiac electric sources we must measure the distribution of heart potentials in the cardiac cavities, in the atrial and ventricular walls, on the endocardial and epicardial surfaces, in the extracardiac conducting media and on the surface of the body. This can be done by using experimental preparations. On the other hand, computer simulations offer the unique advantage of describing a) the electric sources associated with excitation and recovery; b) the three-dimensional time-varying distributions of potentials and currents within the heart, on its surface, in the extracardiac conducting media and on the surface of the body; c) the relevant electro(cardio)graphic (ECG) signals. The analysis of the cardiac electric sources discussed in this report provides a key for understanding the mechanisms that produce the cardiac potential fields, the associated current distributions and the ECG signals. Because epicardial isochrones and potential distributions can be noninvasively computed from body surface ECGs it is clinically important to understand the relationships between epicardial (or endocardial) electrical phenomena and the actual, intramural current sources associated with excitation and recovery.