| Objectives:The structural and functional abnormalities of coronary microcirculation play a pathogenic role in many cardiovascular diseases, and have a prognostic significance. It was found that many diseases have endothelial functional abnormality in coronary artery with normal coronary artery arteriogram, including aging, hypertension, left ventricular hypertrophy (LVH), hyperlipidemia, diabetes mellitus, cardiomyopathy, long period smoking and lack of estrogen. A lot of evidences showed that endothelial functional impairment induce cardiac microangiopathy. Up to now, the means to study myocardial microcirculation are seldom. Myocardial contrast echocardiography (MCE) is one of very effective methods to assess microvascular function. The time-intensity curve manifested by MCE can evaluate relationship of blood flow and volume, thereby it can reflect coronary flow reserve with reality. The purposes of this study are: (1) to discuss the influences of acute hyperglycemia on coronary blood flow (CBF) and coronary blood flow reserve (CFR) in epicardial coronary artery and myocardial microvessles with endothelial independent vascular dilator dipyridamole and nitroglycerin; (2) to try to found out an effect of acute hyperglycemia on CBF and CFR in epicardial coronary artery and myocardial microvessles when myocardial oxygen consumption (MVO2) was increased by intravenous dobutamine; (3) to research whetherhypertension accompanies myocardial microangiopathy and it's relationship to severity of disease and hypertensive LVH, and the value of electrocardiographic changes of ST segment and T wave to estimate myocardial microangiopathy.Materials and Methods:1. Experimental study: Eleven healthy adult mongrel canines were anesthetized , opened chest, and instrumented, and then suspended pericardium cradle and freed anterior descending coronary artery. After obtained optimal two-dimensional left ventricular papillary muscle short axis view, dipyridamole 0.56mg kg-1 (0.142mg-kg-1 min-1 ,within 4min) , dobutamime 40 p g-kg~l-min"1and nitroglycerin 20 u g-min"1 were randomly intravenous injected at basic and hyperglycemia state respectively. The administration interval was at least 20 minutes for each drug, until hemodynamic data were stable. The CBF of LAD was measured with flow meter before and after each drug administration. The ratio of the CBF of LAD between post-drug administration and pre-drug administration was defined coronary flow reserve (CFR). Quanfuxian (a contrast agent consisting albumin and CaFg) was intravenous injected before and after drug administration for MCE, and MCE images were recorded by intermitted harmonic imaging technique and stored in MO disc for offline analysis.2. Clinical study: Twenty-four hypertentives and 8 normal controls were studied with MCE. Quanfuxian (a contrast agent consisting albumin and CsFg) was intravenous injected before and after dipyridamole administration for MCE, and MCE images were recorded by intermitted harmonic imaging technique and stored in MO disc for offline analysis. All patients in each group had normal coronary artery angiography.3. MCE method and image analysis: The MCE images were offline analysed by analysis software. Five to six images before MCE were selected for background images, and 5 to 6 images of each time interval were alsoselected, and then drew the outline of sketch of region of interest (ROI) respectively. The selected images were automatically arranged and aligned by the procedure. With average video frequency intensity (VI) of each ROI in every time point deducted corresponding VI of background images, the procedure drew trigger interval-VI curve of different regions automatically, and present values of A, 3 and A ?3 . Previous studies have testified that the hemodynamic effect of micro-bubbles of contrast agent is similar to erythrocyte, thus, the local filling velocity of contrast agent (3) represents local blood flow's velocity, and the maximum of micro-bubbles accumulated in...
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