| Background One of the most important pathophysiologic features of coronary artery disease (CAD) is the abnormality of myocardial blood perfusion (MBP). A rapid and correct estimate of MBP plays a very significant role during the diagnosis and cure of CAD. Over the last few years, there have been several advancements in the area of myocardial contrast echocardiography (MCE). Being different from coronary angiography and radionuclide, MCE is provided with more unique advantages and is hopeful to be the substitute of these deleterious procedures. At the same time there are many problems still remain unresolved especially on the methodology of MCE. Until the end of 1999, ECG triggering technology had been needed during the MCE, which provides much better visualization of myocardial contrast. However, the triggering technology rules out the information of wall motion function during a stress perfusion exam, the basis of a current stress echo exam. In addition, triggering makes the MCE exam more difficult, requiring the clinician to maintain a window for four seconds or more between images. Real-time myocardial contrast enhancement imaging (Real-time MCE) is a new kind of myocardial perfusion detection technology. It can show the myocardial contrast agents perfusion and ventricular motion function simultaneously, thus may be more versatile than the common MCE for identifying the presence and extent of myocardial perfusion defects. However its reliability in routine practice is unclear.In this serial experimental study, we suppose that Real-time MCE may offer more very important advantages than the common triggering MCE for the assessment of canine myocardial perfusion during normal and graded coronary stenosis, after acute myocardial infarction. We designed the study to evaluate the feasibility and accuracy of intravenous Real-time MCE for the detection of the canine myocardial perfusion changes in canine graded coronary stenosis and acute myocardial infarction models.Study I The instrumental setting and the facts on which will affect myocardial contrast enhancement in intravenous Real-time MCEObjective: To probe into the best instrumental settings of Real-time MCE and the facts on which will affect canine myocardial contrast enhancement in the evaluation of canine normal myocardial perfusion.Methods: Eight open-chest canine models were established. Real-time MCE, using intravenous injection of a Perfluorocarbon contrast agent by two methods with intravenous infusion using a minim injection pump (5ml/min andlOml/min) and a slow bolus injection, were performed. The myocardial contrast agent perfusion and wall motion function of left ventricular walls was observed on the middle of papillary muscles scan plane with different instrumental settings. Results: Real-time MCE can show myocardial contrast perfusion and wall motions simultaneously with most default settings except lowering the receive gain to 50%. In addition, the flash contrast imaging revealed the reperfusion of the contrast agent well with five impulse frames.Conclusion: Having been performed significantly easily, Real-time MCE got many advantages of triggered imaging. It shows the myocardial microcirculation and wall motion function simultaneously with a few influential factors. High tissue motion sensitivity, however, induced blooming artifacts in the field and will weaken the efficiency of Real-time MCE.Study II The experimental study on canine normal myocardial perfusion with intravenous Real-time MCEObjective: To assess the value of Real-time MCE in the evaluation of canine normal myocardial perfusion.Methods: Twenty open-chest mongrel canine models with non-flowing-limiting were established. Real-time MCE were performed with intravenous infusion (5ml/min and lOml/min) of a Perfluorocarbon contrast agent using a minim injection pump. The myocardial contrast agents perfusion and wall motion function of left ventricular walls was observed on the middle of papillary muscles scan plane.Results: Real-time MCE showed not only the...
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