Myocardial electrical impedance responds to ischemia and reperfusion in humans

Myocardial electrical impedance (MEI) is correlated to ischemia and reperfusion of the heart muscle. The entire body of work with MEI to this point has been carried out in nonhuman animal subjects and excised tissue samples. In this study we measured MEI clinically for the first time in human patients who were undergoing off-pump coronary artery bypass (OPCAB) surgery. Our patient population had a 70-100% stenosis of the coronary artery targeted for bypass. We measured MEI continuously during surgery and at 3, 6, 24 and 72 hrs postop from two temporary pacing electrodes attached to heart. MEI increased with occlusion of the diseased artery prior to bypass. The percent increase from baseline was correlated to the percent stenosis of the artery. MEI decreased below baseline immediately on reperfusion following bypass and continued decreasing over the measurement period. MEI is a reliable clinical indicator of ischemia and reperfusion in humans.