EVALUATION OF DYNAMIC CHANGES IN MICROVASCULAR FLOW DURING ISCHEMIA-REPERFUSION BY MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY

Background. Dynamic changes of myocardial blood flow have been observe d after reperfusion of an occluded coronary artery. MCE performed by i ntracoronary contrast injection can pro, ide an estimate of microvascu lar flow. We hypothesized that MCE performed using intravenous infusio n of a new generation contrast agent and electrocardiogram gated harmo nic imaging would be able to assess serial changes of microvascular pe rfusion. Objective. To study the potential of myocardial contrast echo cardiography (RICE) to assess serial changes of microvascular flow dur ing ischemia-reperfusion.Methods. Sixteen dogs underwent 90 or 180 min of left anterior descending coronary occlusion, followed by 180 min o f reperfusion. Regional blood flow (RBF) nas measured,vith fluorescent microspheres at baseline, during coronary occlusion, and at 5, 30, 90 , and 180 min during reperfusion. At the same time points, MCE was per formed with intravenous infusion of AF0150 (4 mg/min). Gated end systo lic images in short axis were acquired in harmonic mo de and digitized on line. Background subtracted videointensity measured from MCE and R BF obtained from fluorescent microspheres were calculated for the risk area and for a control area, and were expressed as the ratio of the t wo areas. Results. After initial hyperemia, a progressive reduction in flow mas observed during reperfusion. MCE correctly detected the time course of changes in flow during occlusion-reperfusion. Video-intensi ty ratio significantly correlated with RBF data (r = 0.79; p < 0.0001) . Conclusions. The progressive reduction in blood flow occurring withi n the postischemic microcirculation was accurately detected by MCE. Th is approach has potential application in the evaluation and management of postischemic reperfusion in humans. (C) 1998 by the American Colle ge of Cardiology.