Real-time measurement of the spatial magnitude of the ST segment with the automated vectorcardiographic ST segment...

ST segment deviation has been used as an indicator of the degree of myocardial ischemic injury. An automated vectorcardiograph, i.e., an ST segment analyzing system developed in our laboratory, was applied to experimental coronary artery occlusion in dogs, and continuous real-time measurements of ST segment deviation were undertaken. ST segment deviations of the X, Y and Z leads of the Frank lead system were measured and averaged during eight-second periods (STX, STY and STZ). From the ST segment deviation in three dimensions, the spatial ST magnitude and the direction of ST segment deviation (azimuth and elevation) were computed with the use of a microcomputer. The spatial changes of the ST segment after the occlusion of the coronary arteries in the experimental animals were quite compatible with the site of the occlusion. In addition, various interventions influenced the spatial magnitude of the ST segment resulting from coronary artery occlusion.