Assessment of myocardial postreperfusion viability by intravenous myocardial contrast echocardiography - Analysis of the intensity and texture of opacification

Background-Although defects on intracoronary myocardial contrast echocardio graphy (MCE) indicate loss of viability after reperfusion, opacified segmen ts may also exhibit persistent dyssynergy. Therefore, we related the intens ity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissu e by postreperfusion MCE. Methods and Results-MCE was performed by intravenous injection of 0.15 mL/k g QW7437 in 14 dogs who underwent 3-hour coronary occlusion followed by 3-h our reperfusion, At baseline and 3 hours after reperfusion, midventricular short-axis images were digitized and segmented. Infarction fraction (IF) fo r each segment was determined by triphenyltetrazolium chloride stain. Of 22 4 segments, 140 showed no or small infarction and served as a control group . Of 84 segments with significant infarction (IF>30%), 52 exhibited a defec t on MCE, and 32 exhibited no defect. Echo texture was quantified by comput ing entropy based on the co-occurrence matrix analysis of gray-level pairs within each segment. Three hours after reperfusion, average and maximal ent ropies in the infarct segments without opacification defects were significa ntly higher than control levels. Histologically, the degree of intracapilla ry erythrocyte stasis was less in this group than in the infarcted segments with MCE defects with similar magnitude of tissue injuries. Conclusions-Opacification defects by MCE may be present or absent in myocar dium with histologically confirmed infarction, The texture of MCE from opac ified but infarcted myocardium differed significantly from control segments and may assist in determination of segmental viability after reperfusion.