Assessment of risk area during coronary occlusion and infarct size after reperfusion with myocardial contrast echocardiography using left and right atrial injections of contrast

Abstract

Background. Myocardial opaciflcation during echocardiography has been demonstrated after left (LA) and right (RA) atrial injections of contrast, and microvascular damage with reduced blood flow and impaired flow reserve has been documented in necrotic myocardial tissue. Therefore, we hypothesized that because of its ability to depict capillary perfusion, myocardial contrast echocardiography (MCE) can be used to define risk area during coronary occlusion and infarct size after reperfusion with LA and RA injections of contrast in the presence of pharmacologically induced coronary hyperemia. Methods and Results. Eighteen open-chest anesthetized dogs with 3 to 6 hours of left anterior descending artery occlusion and 15 minutes of reflow were studied in the presence of either dipyridamole (0.56 mg/kg over a period of 4 minutes) or dobutamine (15 μg · kg-1 · min-1). Technetium autoradiography was performed for risk area assessment; infarct size was measured with triphenyl tetrazolium7 chloride; and in 11 dogs, myocardial blood flow was measured with radiolabeled microspheres. A close linear relation was noted between the MCE defect size and autoradiographic risk area during coronary occlusion both during LA (y=0.95x-0.25, r=.97, P