Magnetocardiographic analysis of the two-dimensional distribution of intra-QRS fractionated activation

The spatial distribution of high-frequency components in magnetic signals d uring the QRS complex of the human heartbeat was investigated. Cardiomagnet ic signals were recorded simultaneously using 49 first-order magnetogradiom eter channels of a multi-SQUID system with a low noise power density. The Q RS fragmentation score S, as a measure of the fragmentation of the bandpass -filtered QRS complex, was examined for its sensitivity and specificity to discriminate 34 healthy volunteers, 42 post-myocardial infarction patients and 43 patients with coronary heart disease and with a history of malignant sustained ventricular tachycardia or ventricular fibrillation. The multich annel information was visualized by two-dimensional mapping of the score va lues of the single channels. By averaging the score values for the seven ce ntral channels, S-7, the score values of all 49 channels, S-49, and calcula ting the standard deviation for all 49 channels, D-49, a higher sensitivity and specificity for detecting patients with ventricular tachycardia (VT) o r ventricular fibrillation (VF) was reached than by analysis of a single ch annel. Combination of these parameters furnishes a sensitivity of 90% and a specificity of 70% for identifying patients prone to VT/VF. The results were compared with diagnostic information obtained From the QRS duration of the signal as well as with results obtained by modified QRS in tegral mapping.