| Objective The persistence of an intact microcirculation after prolonged ischemia is a basic factor for the myocardium to stay alive. The aim of this study was to evaluate the ability of myocardial contrast echocardiography (MCE) in assessing myocardial viability (MV). Different methods of MCE were used to compare with positron emission tomography (PET) and low dose dobutamine stress echocardiography (LDDE) clinically, and with pathological examination and radiolabled microsphere in animal study. Methods I. Seven dogs were ligated at the proximal of left anterior descending coronary artery to create acute myocardial infarction models. 4 hours after coronary ligature, microbubbles were administered as a constant venous infusion, and MCE was performed with the use of different pulse intervals at 150 to 200ms, 1,2,5,9,18,27,36, and 45 cardiac cycles. The video intensity versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: yA(1-e- f3 t), where y is VI at pulsing interval t, A reflects microvascular cross-sectional area (or myocardial blood volume), and P reflects mean myocardial microbubble velocity. The product of A~B represents MBF. Radiolabeled microsphere-derived MBF and pathological technology was used to verify the reliability of MCE in the determining of myocardial viability. 2. MCE with the method mentioned above was performed in 19 consecutive anterior myocardial infarction patients after successfully revascularization with LAD.,and the results were compared with PET. 3 MCE with bolus intraveneous, injection microbubbles were performed in 13 consecutive anterior myocardial infarction patients after successful PTCA&stent, and -4- the results were compared with LDDE and PET. 3. Real-time myocardial contrast echocardiography (RTMCE) with coherent contrast imaging (CCI) protocol provided by Acuson were performed in 12 volunteers and 10 anterior myocardial infarction patients. MV was determined from myocardial perfusion in combination with wall motion, and the results were compared with PET. Results 1. Aj3 in the normal, ischemic, and infarct region was 52.46?15.09, 24.36?.89, and 3.74?.80 in the animal study. The normalized A13<0.23 means myocardial necrosis, this result was coincided with pathological result. 2. In the clinical trial, A~f3 in normal and infarct region was 62.41 ?12.97 and 3.61 ?1.69 respectively, and normalized A~f3 in necrosis region was less than 0.23, and MV determined by MCE was coincided with that of PET results. 3. For the detection of MV with LDDE, MCE, and MCE+LDDE, the sensitivity were 82%~ 89%.~ 92% respectively. The specificity were 79%~. 57%., 82% respectively. The positive predict value were 85%~ 82%.. 90% respectively. The negative predict value were 76%.. 71%.. 85% respectively. 4. For the detection of MV with RTMCE, all segments are viable in the normal group. In the myocardial infarction group, 128 segments are viable and 26 segments are necrosis, and the results were coincided with the PET results. Conclusions 1. MCE can be used to assess MV by quantification of myocardial blood flow. 2. MCE combination of LDDE can raise the sensitivity and specificity in the detection of MV. 3. RTMCE may be a new method in the detection of MV.
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