REDUNDANCY REDUCTION FOR IMPROVED DISPLAY AND ANALYSIS OF BODY-SURFACE POTENTIAL MAPS .1. SPATIAL COMPRESSION

The Karhunen-Loeve technique of random process representation was investigated as a method of quantitatively characterizing body surface potential maps. Lead body surface potential maps (192) from 124 normal subjects and 97 patients with independently documented heart disease were used in the study. Each map frame in QRS and ST-T of 34 maps in a test set was represented as a linear sum of orthonormal distributions derived from the covariance matrix estimated from all QRS frames in the 221 training maps. At 16:1 reduction in spatial data of the test set was achieved with rms [root mean square] errors of 45 and 21 .mu.V in QRS and ST-T, respectively. Apparently 12 independent waveforms, derived from the 192 measured ECG, may be used in place of those 192 ECG. In addition to providing a convenient and familiar method of display for map data, the technique puts the data in an appropriate form for quantitative statistical analysis.