Myocardial Electrical Impedance Correlates with Ischemic ECG ST-Segment Changes in Humans

Electrocardiogram (ECG) ST-segment changes are commonly used to diagnose myocardial ischemia. In this study we compared ST-segment changes with changes in myocardial electrical impedance (MEI) - an electrical parameter that also responses to ischemia - during off-pump coronary artery bypass graft (OPCABG) surgery of the left anterior descending coronary artery (LADa). We recorded MEI and ST-segment changes in eight patients during OPCABG surgery and compared the change in MEI that occurred when the LADa was occluded just prior to the beginning of the revascularization procedure with the ST-segment changes during the same period. Myocardial electrical impedance changes were directly and significantly correlated with ST-segment changes in our patient population. Our results indicate that MEI is equivalent to ST-segment changes as a measure of myocardial ischemia