HIGH RESOLUTION MAGNETO-CARDIOGRAPHIC FIELD MAPPING AND ANALYSIS.

High-resolution magnetocardiograms have been measured for nine normal subjects and one patient with a myocardial infarction. The measurements are obtained at 56 locations in a plane near the anterior chest wall. As part of the analysis, this data has been recognized to display the magnetic field of the heart each 2 ms of the heart cycle. Using the Karhunen-Loeve expansion such spatial maps can be represented by a set of orthogonal basis-functions. These basis-functions are then used to extract from the maps underlying patterns not represented by the basis-functions. Applying this analysis to the atrial repolarization pattern of the normals enabled the authors to identify signals characteristic of the His-Purkinje system. A similar analysis was used to extract patterns representing the infarction vector of the patient with the infarction.