Abstract
The interruption of myocardial oxygen supply in acute ischemia alters the O2 content of coronary venous blood. The oxygenation status of coronary sinus blood was assessed by intravascular application of near-infrared spectroscopy in 10 domestic pigs under in-vivo conditions. Calibration of the catheter was performed in vitro by perfusion of blood with gas mixtures of various O2 concentrations. The catheter was placed into the coronary sinus, and anterior wall ischemia was induced by temporary occlusion of the left anterior descending coronary artery. Spectroscopic and hemodynamic data were obtained. The main differences between oxygenated and deoxygenated hemoglobin were found with O2 concentrations < 30%, corresponding to the coronary sinus blood O2 content. Spectrographs showed variations related to CO2 concentration, pH, and temperature. Spectral analysis showed significant differences between pre-ischemia and ischemia. Variations in spectrographs could be observed in both in-vitro and in-vivo experiments. The intravascular application of near-infrared spectroscopy is technically feasible and can be used as a reliable tool in detection and follow-up of tissue deoxygenation, particularly in acute myocardial ischemia.
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