ECG mean-power as primary indicator of myocardial ischemia

In order to cause myocardial ischemia, the left anterior descending (LAD) branch of the coronary artery was occluded and released twice in five dogs. The occlusion-release times and the ECG was recorded. Using an epicardial lead in the necrosis zone for each dog, spectrograms were obtained. The spectrograms showed great changes related to the perfusion status in the lowand high-frequency regions. As a numerical indicator, for each recorded lead, the normalized mean power was calculated for both the low-frequency region (1-10 Hz) and the high-frequency region (30-100 Hz). As a cardiac ischemia indicator, the normalized low-frequency mean-power (LFMP) plot was obtained. When the coronary occlusion begins and then remains, this graphic plot shows an increase in the LFMP, whereas coronary releasing causes the recovery of the initial LFMP level.