COMBINATION OF DOBUTAMINE AND MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY TODIFFERENTIATE POSTISCHEMIC FROM INFARCTED MYOCARDIUM

Objectives. This study tested whether the combination of dobutamine ec hocardiography (DE) and myocardial contrast echocardiography (MCE) was superior to either technique alone in identifying postischemic myocar dium and in differentiating it from necrotic myocardium. Background. W all motion abnormalities at rest occur in postischemic myocardium in t he presence of infarction, stunning or hibernation, alone or in combin ation. Various investigators have suggested that either DE or MCE can be used to identify the presence of myocardial viability. Methods. We studied a total of 53 mongrel dogs in an open chest model of coronary occlusion of various durations followed by reperfusion and dobutamine administration (10 mu g/kg body weight per min). MCE with aortic root injections of Albunex (area under the curve) and DE (percent thickenin g fraction) were performed at the different stages, Postmortem triphen yltetrazolium chloride (TTC) staining was used to identify myocardial necrosis. Results. Thirteen dogs underwent brief (15 min) occlusions a nd developed no necrosis (Group I). Of 40 dogs that underwent prolonge d (30 to 360 min) occlusions, 14 had no infarction (Group II), whereas 26 did (Group III: 12 papillary muscle, 7 subendocardial, 7 transmura l), MCE (expressed as percent change from baseline) demonstrated chang es that paralleled the blood how changes observed by radiolabeled micr ospheres at all interventions (r = 0.67, p < 0.0001). Regional ventric ular function improved with dobutamine administration in the ischemic region in all three groups, The sensitivity (88%) for detecting myocar dial viability was superior when the two techniques were combined; how ever, a poor specificity (61%) was observed, Conclusions. Contractile reserve and perfusion data are complementary when assessing regional w all motion abnormalities in postischemic myocardium. DE alone cannot d ifferentiate postischemic from infarcted myocardium; simultaneous data on myocardial perfusion are required, The combination of DE and MCE i s superior to either technique alone for identifying the absence of my ocardial necrosis.