[Mathematical model of the electrical field in ischemic hearts]

The distribution of injury potentials on the cardiac and thoracic surface has been simulated by means of a simple, two-dimensional mathematical model utilizing the solid angle theory. The endocardial, epicardial and thoracic surfaces were represented by three concentric circumferences with radius of 2, 3 and 8 cm; the calculations have been performed with a digital computer (PDP 11/40). Five groups of ischemias have been considered according to their geometrical characteristics: three groups of ischemias affecting the entire ventricular wall, one group of subepicardial and one of subendocardial ischemias. The distribution of epicardial potentials clearly indicated the axis of symmetry and the epicardial border of all the ischemias where such a border existed. Conversely, visual inspection of the curves depicting the distribution of precordial potentials enabled little or no insight to be gained into the location and geometry of the ischemic areas; however, the epicardial or endocardial borders of the ischemic region could be easily determined from precordial data by using the mathematical model. In conclusion, detailed mapping of precordial injury potentials make it possible to obtain significant information on the location and geometry of myocardial ischemias, provided a suitable mathematical model is available.