| ObjectiveThe ability to evaluate myocardial perfusion by a quick and simple noninva-sive method would be of great value in patients with coronary artery heart disease. In the clinic, currently the only diagnostic procedure is radiology scintig-raphy. With the improvement of the equipment and the development of the contrast agent, it is possible to assess myocardial perfusion with myocardial contrast echocardiography (MCE) by intravenous injecting contrast agent. Now intravenous MCE is a hot topic in the echocardiography field. But it is still at the stage of research. And there are not receipted standard in the examination and analysis. In China, there is few research in this fields because there is no commercially available contrast agent. The purpose of this study is to evaluate myocardial perfusion with MCE by intravenous self-made contrast agent in normal open chest dogs and dogs with coronary artery occlusion and reperfusion. To determine the size of the risk area and infarct area during occlusion and the ultimate infarct area after reperfusion, the myocardial salvage is also evaluated.MethodsPreparation of sonicated contrast agentSelected aliquots of 5% human albumin and 5% dextrose or Dextranum 40 were mixed in 20ml upright syringe which connect to one of the three path cathe-ters. A sonicator (Sonic & materials) is used to created micro bubbles. With the sonicating probe initially placed just below the surface of the mixture liquids, the sonication proceeded at output levels 80 or 100 for 120s, 150s, and 180s. During the early time of the sonicating, 1ml perfluorocarbon gases were injected to the bottom of the syringe from another end of three path catheters. U-sing the 0.5ml lowest liquids, the left is sealed for preparation. Three samples were made for every condition. The size and concentration of micro bubbles were measured under the light microscopy by the improved Neubauer method.MCE protocol in the normal open chest dogsAnimal preparation Two mongrel dogs (weight, 17kg and 20kg) were used for the experiment. They were anesthetized with 30mg/kg of sodium pento-barbital, intubated, and ventilated by respirator pump. A catheter was introduced into right femoral veins for contrast agent injection. A medial thoracotomy was performed, and the heart was suspended in a pericardial cradle.MCE protocol Intermittent harmonic imaging was performed in the pa-rasternal short - axis plain at mid papillary muscle level with the Hp 5500 Sonos system. The transducer was placed in a water bath over the heart which served as an acoustic interface, with the mechanical index set to 1.6. At the beginning of the experiment, the gain, the depth and the focus were adjusted at the baseline and the myocardium was almost black and only endocardial bounders should be visible. The parameters of the equipment were held throughout the experiment. The baseline 2D image was acquired. Self - made contrast agent, total dose is 12ml, was intravenous injected by a gently agitate infusion pump ( B/ Braun) at a rate of 1.5ml/min. End -systolic images were obtained at pulsing intervals ranging from 3 to 10 cycles,, The double frames were used. The second image was acquired 15ms after the first one and used as a background image to avoid artifacts. All images were recorded on the MO disk. The EGG was monitored during the experiment.The MCE protocol in the dogs with acute myocardial ischemia and reperfusionAnimal preparation Twelve mongrel dogs were used. They were anesthe-tized with 30mg/kg of sodium pentobarbital, incubated, and ventilated by respirator pump. Two catheters were introduced into double femoral veins to infuse contrast agent and fluids. A median thoracotomy was performed, and the heart was suspended in a pericardial cradle. The proximal of the left arterial descending coronary artery (LAD) was dissected freely from surrounding tissue and was occlusion for 4 hours, followed by 1 hour reperfusion.MCE protocol The protocol of MCE is the same as in the normal case. The trigger inte...
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