| Part I Animal Experimental StudyObjectives: To have a further realization of the mechanism of hibernating myocardium and its image characteristics on echocardiography,MRI and SPECT.Materials and Methods: The LCX of coronary artery of 10 pigs were obstructed by Ameroid occlusions to make hibernating myocardium model .Echocardiography , MRI and 201-TI SPECT were performed before ,2 weeks or 5weeks after operation and compared with histopathologic examination.1.Echographic Measurements Conventional measurements( LV wall thickening in the area at risk ,fraction shortening and ejection fraction) were obtained from gray-scale M-mode tracings. With color-coded M-mode TDI, the endocardial ,epicardial velocities and the myocardial velocity gradient( MVG) were calculated within posterior wall from left ventricular long-axis view. The time-velocity curves and MVGs of several points were obtained from short-axis view at papillary muscle level. After 10μg/(kg.min) and 20μg/(kg.min) dobutamine stress, these indexes were measured again. The IBS indexes( CVIB and AII) of posterior wall were obtained from short-axis view at papillary muscle level.2.MRI Imaging Multiple applications of fast MRI techniques were performed ,such as morphology scanning, cine MRI, myocardial perfusion and viability imaging.3.201-TI SPECT Imaging Images were acquired 15 minutes later after dipyridamolestress . 2 hours later, delayed -rest images were obtained.4.Pathological Examination EVAN's blue dyes were injected in the LCX, just distal to the Ameroid occlusion .Each transverse heart slices was inculated for 15 minutes in a 1% solution of TTC at 37℃, then were examined under microscope.Results:1.Normal pigs a)Echocardiography displayed that each lumen of the heart was normal size and the myocardium had good contractile function. Vendo was 3.44±0.70cm/s,Vepi 1.58±0.70cm/s,MVGm 5.36±1.60/s, The TVC of the septum and posterior wall were 3.54±0.87cm/s,4.03±0.66cm, respectively. b) On the MRI image, normal myocardium exhibited rapid, uniform first-pass signal enhancement and lack of delayed regional hyperenhancement. c) 201-TI SPECT The radionuclide was well distributed, no perfusion defects were seen. 2.6 of 10 pigs were made hibernating myocardium model successfully. The histopathology examination mainly showed myocardium denaturation with a little necrosis.3.Model pigs a) Echocardiography At the 2th and 5th week after operation ,the lumens of the heart were normal. 2 pigs had abnormal regional contractile ,the location and range of which were coincident with the risk area. After the 2 weeks of ischemia , the Vendo,Vepi ,MVG of the systolic stage and diastolic stage ,the thickening of the posterior wall from short-axis view depressed significantly. Compared with pre-operation ,the Vendo,Vepi ,MVG of the systolic stage were still lower at the 5th week,but no significant difference were seen between the 2th week and the 5th week. The indexes of the whole heart function FS and EF didn't change with the time. The IBS index AII showed no difference between the pre-operation and post-operation. Although the CVIB didn't change significantly with the time, it depressed at the 2th week when compared with pre-operation. At the 2th week of ischemia, after injected 5μg/(kg.min) and １ï¼Î¼g/(kg.min) dosage of dobutamine ,each pig manifested improvement of wall motion. At the 5th week of ischemia, the dysfunctional segments displayed improvement at 5μg/(kg.min) and 10μg/(kg.min) dosage ,but deteriorated at 20μg/(kg.min) dosage .At the 2th week,　MVGm after 10μg/(kg.min) stress was lower than before stress. At the 5th week, MVGm after 20μg/(kg.min)stress wasn't different from no stress,but still lower than before operation. The TVC improved evidently after stress, but the change rate of TVC made no difference among diverse points. b) 2 pigs also exhibited depressed systolic function on cine MRI. Hypoe...
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