| Objectives: The most frequent anatomicopathological phenomenon in the early hours of the acute myocardial infarction (AMI) is the total occlusion of the culprit coronary artery. So most of the research interests and therapeutic strategies have been focused on the epicardial coronary arteries. And a lot of procedures concerning the coronary artery reperfusion have been explored to the clinic. But now a days, people are finding when a coronary artery is occluded, detrimental changes occur in the cardiac capillaries and arterioles. After relief of the occlusion, blood flow to the ischemic tissue may still be impeded, a phenomenon known as "no reflow" (NR). This has been more interested by cardiologists now. As the coronary artery intervention in the early stage of the acute myocardial infarction is widely performed and MCE is particularly helpful in identifying NR, the NR phenomenon has been familiarizing now a days, and the protection of the myocardial microcirculation is paid attention as very focusing as the reperfusion of the underepicardiac transport vessel is. Also, the therapeutic methods which should release NR phenomenon effectively and safely are the urgent demand for the clinic.At the beginning of the new century, an ultrasound contrast agent contained perfluoropropane (C3F8) is capable of producing left ventricular myocardial opacification from a peripheral intravenous injection, so as to this kind of myocardial contrast echocardiography (MCE) occupying an very important part in identification NR these days, just because of its simple, non-invasive and accurate advantages. In this technique, C3F8 gas is broken to the microbubble by the high energy sonic boom and is enclosed by dextrose and albumin. After the reperfusion of the AMI target coronary artery, no microbubble perfusion or permanent microbubble staying in the remote region of the culprit coronary artery is usually the exact evidence of NR.The aims of this series study are (I) exploration of the capability of C3F8 MCE imaging left ventricular myocardium from being injected intravenously, and exploration of the characteristics of the MCE myocardial microcirculation image under the situations of the normal coronary artery, acute occluded coronary artery and revascularization coronary artery; (II) exploration of the characteristics of MCE myocardial microcirculation image of the acute occluded and then reperfused coronary artery under the situation of the ischemic preconditioning (IPC), and trying to explain the mechanisms of the myocardial protecting effect of IPC; (III) exploration of the characteristics of MCE myocardial microcirculation image of the acute occluded and then reconstructed coronary artery under the NR phenomenon, in order to introduce the echocardiographic MCE data for the further clinical research on the NR mechanisms; and (IV) exploration of the characteristics of MCE myocardial microcirculation image under the situation of Diltiazem intervention of NR phenomenon, and trying to offer the laboratory parameters for the clinic coronary artery intervention procedures and trying to look for the effective methods on releasing NR phenomenon. The detail methods and results were mentioned as follow.Part I. The MCE study on myocardial microcirculation of the acute occluded and then reperfused coronary artery model in dogs. Methods: (I) preparations of the MCE image agent. The mixture of the human serum albumin and glucose injection was put into a sterile syringe and then, the latter was placed under the probe of the ultrasonic cellular mixer. The mixer was started and the mixing condition was continued for 100 seconds. During the period, C3F8 gas was injected into the mixture. After the mixing situation, the syringe was kept vertically and quietly until the upper white layer of mycrobubble was emerged stably. The upper white layer of microbubble was assessed with hemocytometry. The sizes of the microbubbles were among 4.0 ~ 5.0 um with 90% of them smaller than 7.0 um and the mean concentration of the microbubble...
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