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DOI: 10.1055/s-2008-1038025
Rapid detection of acute regional and global myocardial ischemia using non-invasive visible light spectroscopy
Aims: Monitoring of tissue oxygenation (StO2) by visible-light-spectroscopy (VLS) can be useful for rapidly detecting myocardial ischemia during cardiac surgery, but its' feasibility for cardiac tissue is not known. We tested the ability of VLS to detect changes of StO2 in animals subjected to acute regional and global cardiac ischemia.
Methods: Eleven anesthetized pigs underwent ligation of the left anterior descending artery for 20 minutes. Myocardial StO2, was obtained from the ischemic and a non-ischemic myocardial region of the left ventricle (LV) using a VLS disc-probe (Spectros Corporation, CA, USA). Hemodynamics were recorded at 1,5,10 and 20 minutes of ischemia. StO2 was correlated to coronary venous oxygen saturations (ScO2) and myocardial function (systolic wall thickening, strain) was assessed by echocardiography. In seven rabbits, myocardial StO2 was acquired during and after global cardiac ischemia induced by hypoxia and aortic clamping.
Results: Baseline StO2 did not differ in the ischemic and non-ischemic myocardium (69.6±7.7% vs. 74.1±4.6%). Hemodynamics remained unchanged, but StO2 rapidly declined at 1 (50.5±8.8%) and 5 minutes (42.1±4.0%) after coronary occlusion and remained decreased in the ischemic region with compensatory increases of StO2 in the non-ischemic region. Decreases of StO2 were associated with contractile dysfunction and correlated to ScO2. Further, VLS reliably detected decreases of the RV and LV StO2 after induction of global ischemia in rabbits.
Conclusions: Non-invasive VLS is a reliable and accurate method of detecting alterations in myocardial StO2 and can be a useful monitor for rapid identification of myocardial ischemia occurring during cardiac surgery.