Evaluation of fluorescence microscopy for the identification of necrotic myocardium

The utility of fluorescence microscopy in the evaluation of hematoxylin-eosin-stained sections for the presence of myocardial necrosis was examined. Sixteen human autopsy cases with clinical and pathologic evidence of myocardial infarction were studied. In addition, to better define the sensitivity and specificity of this technique, the hearts of 20 dogs that had undergone experimental coronary occlusion of known duration were studied; the duration of occlusion was three hours in seven dogs, six hours in seven dogs, and seven days in six dogs. In both human and dog studies, hypereosinophilic necrotic fibers in hematoxylin-eosin-stained sections appeared bright yellow by fluorescence microscopy. In myocardium that was shown to be necrotic by triphenyltetrazolium chloride staining and electron microscopy but was not hypereosinophilic, there was no bright yellow fluorescence of myofibers. Our study shows that bright yellow fluorescence is related to hypereosinophilia of myofibers and thus can be used to detect myocardial necrosis. However, since only hypereosinophilic fibers show the characteristic yellow fluorescence, the method appears to offer no distinct advantages over routine light microscopic techniques.