Detection of early myocardial tissue changes in acute canine myocardial infarction by ultrasonic tissue...

To determine the time after left anterior descending (LAD) artery occlusion in which myocardial texture changes first occur, two-dimensional echocardiograms on five sham operated dogs and eight dogs before and after proximal LAD occlusion were performed. Serial two-dimensional echocardiograms were performed every 15 mins by placing a 5 MHz transducer directly on the chest wall. The dogs were sacrificed at the end of the study and the area of myocardial infarction was confirmed by triphenyltetrazolium chloride staining. The two-dimensional echocardiogram images were digitized. The mean pixel intensity +/- SD in the area of myocardial infarction (region of asynergy) and a normally moving area (control region) equidistant from the transducer were calculated; thus, each dog served as its own control. In sham operated dogs, no significant changes in mean pixel intensity, skewness or kurtosis were observed. There was a significant increase (P less than 0.01) in mean pixel intensity in the infarcted regions (anteroseptal) compared to values obtained in the normally moving (lateral) regions at 30 mins (mean pixel intensity 25.2 +/- 2.1 versus 23.0 +/- 0.7, P less than 0.05); this difference persisted at 45 mins (mean pixel intensity 25.8 +/- 0.9 versus 22.6 +/- 0.5, P less than 0.01), 60 mins (mean pixel intensity 27.2 +/- 1.4 versus 22.8 +/- 0.8, P less than 0.01), 90 mins (mean pixel intensity 28.6 +/- 1.6 versus 22.5 +/- 0.9, P less than 0.01) and 180 mins (mean pixel intensity 28.7 +/- 1.8 versus 21.3 +/- 1.4, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)