Myocardial electrical impedance (MEI) is correlated to ischemia and reperfusion of the hearth muscle. The entire body of work with MEI to this point has been carried out in animal subjects in vivo and excised tissue samples. In this study, we measured MEI clinically for the first time in human patients who were undergoing off-pump coronary aratery bypass (OPCAB) surgery. MEI was measured with a monitor designed in this laboratory and approved by the FDA for use on human subjects. Our patient population (n = 18) had a 70%-100% stenosis of the diseased coronary artery targeted for bypass. We measured NIEL continuously during surgery and at 3, 6, 24, and 72 h postoperatively from two temporary pacing electrodes attached to the heart muscle. Absolute baseline impedance ranged from 173 to 729 ω. MEI increased with occlusion of the diseased artery prior to bypass. The percent increase from baseline was inversely correlated to the percent stenosis of the diseased artery. MEI decreased below baseline immediately on reperfusion following bypass in all patients and continued decreasing over the measurement period. NIEI is a reliable clinical indicator of ischemia and reperfusion in humans and may indicate the effectiveness of coronary artery surgery. The parameter may have monitoring and diagnostic value in heart disease in humans.
- Myocardial electrical impedance
ASJC Scopus subject areas
- Biomedical Engineering