Online detection of myocardial ischemia by near infrared spectroscopy witha fiberoptic catheter

Background: The interruption of myocardial O-2-supply in acute myocardial i schemia causes differences in coronary venous O-2-content. In this study, t he oxygenation status of coronary sinus blood is detected in myocardial isc hemia by near infrared (NIR) spectroscopy. Method: For the intravascular ap plication, a new fiberoptic catheter is developed. After calibration of the catheter by perfusion of blood with standardized gas mixtures in an in vit ro experiment, the in vivo application was performed in 12 domestic pigs. T he catheter was placed into coronary sinus and an anterior ischemia was ind uced by temporary occlusion of LAD. NIR graphs and hemodynamic data were ob tained for 90 min ischemia and 90 min reperfusion time. Results: Main NIR-s pectroscopic differences between oxygenated and de-oxygenated hemoglobin to ok place in O-2-concentrations less than 30%. Coronary sinus NIR spectra of hemoglobin-oxygen binding showed significant, reproducible differences bet ween pre-ischemia, LAD-occlusion and reperfusion. NIR graphs also show vari ations related to CO2-concentration, pH and temperature. Conclusion: The in travascular application of NIR spectroscopy could be a reliable tool in det ection and follow-up of acute myocardial ischemia and infarction.