938-60 Detection of Experimental and Clinical Myocardial Infarction by High Frequency Ultrasound

Abstract

To determine whether myocardial changes in acute myocardial infarction are detectable by high frequency ultrasound imaging, the left anterior descending coronary artery of 10 rats was ligated and 1 rat was sacrificed after 1 day and 3 rats were sacrificed after 2 days, 3 rats after 3 days and 3 rats after 4 days. Two rats served as sham operated controls. Unstained, 5 μm sections of rat hearts were placed on a glass slide and imaged with a 600 MHz transducer. In addition, sections of myocardium obtained at autopsy from 1 pt with acute myocardial infarction were also imaged. A serial section from each of the hearts was imaged by light microscopy. Ultrasound images of control rats and 1 day myocardial infarction showed cardiac myocytes arranged in long axis both in the anterior wall and septum. The anterior wall in the 2 day, 3 day and 4 day infarcts showed cell loss in the subendocardium and subepicardium and discrete rounded echo dense particles which corresponded to inflammatory cell infiltration on light microscopy. Between these areas were hypoechoic myocytes which corresponded to coagulation necrosis on histology. The septum (control region) showed normal myocytes. In acute myocardial infarction in man, cell necrosis and cellular infiltration was noted in the infarcted region. Thrombi in intramyocardial arterioles were seen. The changes were confirmed by light microscopy. High frequency ultrasound imaging depicted characteristic changes in acute myocardial infarction. Further development of this technique for possible IN VIVO evaluation of myocardial ischemia and differentiation of infarcted from viable myocardium appears warranted.