【作者】 秦超；

【导师】 何涛；

【作者基本信息】 广西医科大学 ， 心血管科内科， 2012， 硕士

【摘要】 背景与目的心肌梗死(myocardial infarction, MI)是当前世界范围内致死和致残的主要疾病之一,心肌梗死的诊治一直是研究的重点。心肌梗死动物模型的建立是进行心肌梗死实验研究的必要前提。结扎大鼠冠状动脉左前降支(LAD)是经典的心肌梗死模型制备方法,其关键步骤之一是判断模型是否成功建立。心电图对急性、演变中或新进心肌梗死的诊断具有重要价值,诊断依据之一是心电图出现ST段偏移。实验研究中普遍应用心电图判断动物心肌梗死模型是否成功建立,而实验中多数采用肢体导联特别是Ⅱ导联监测心电图的变化,也有学者应用了胸导联。我们既往的研究显示结扎大鼠LAD后各肢体导联ST段抬高的出现率均小于80%。胸导联的导联轴位于横面,面对心脏的前壁与侧壁,LAD闭塞主要引起前壁梗死,故胸导联能检测到LAD闭塞后引起的心肌梗死特征性的心电图变化,且理应较肢导联更准确地予以反映结扎LAD后引起的心肌梗死,但尚未见有相关报道。多糖是由许多相同或不同的醛糖或者酮糖以A2或B2糖苷键连接而成的一类具有广泛生物活性的生物大分子,具有复杂的生物活性与功能,有研究提示某些植物多糖如麦冬多糖、芦荟多糖对心肌梗死具有保护作用。前期研究中本课题组己从甘蔗叶中成功提取了多糖,甘蔗叶多糖是否与其他一些植物多糖类似对心肌梗死具有保护作用尚未见有报道。本研究通过结扎大鼠LAD建立心肌梗死模型,同步记录大鼠肢体导联与胸导联共9个导联的心电图,比较胸导联与肢体导联对结扎大鼠LAD所形成心肌梗死的诊断价值；以甘蔗叶多糖对大鼠心肌梗死模型进行灌胃,通过测量大鼠左心室病理切片的梗死区域面积观察甘蔗叶多糖是否具有缩小心肌梗死面积的作用。方法75只健康雄性SD大鼠,经腹腔麻醉后,建立人工通气,开胸结扎LAD,同步记录大鼠术前、术后30分钟、60分钟的9导联心电图,测量除aVR导联外的各导联ST段偏移幅度及ST段发生变化的出现率,并进行统计学分析。根据心电图ST段抬高与否,将出现ST段抬高的大鼠随机分为甘蔗叶多糖组与生理盐水组。术后24小时,以甘蔗叶多糖溶液、生理盐水对两实验组分别实行灌胃处理,持续5天后处死。取材心脏,分离左心室,制成HE染色病理切片,测量左心室梗死区域面积及左心室切片面积,大鼠的梗死面积公式：梗死面积=左心室梗死区域面积/左心室切片面积×100%,比较两组左心室梗死区域面积与左心室切片面积的比值是否存在差异。结果大鼠心肌梗死模型的心电图,除Ⅲ导联外,其它导联结扎后30min、60min的ST段均较术前升高(P<0.05)；在胸导联V2、V5ST段较术前升高的幅度高于各肢导联(P<0.05),V1导联高于Ⅱ、aVF导联(P<0.05),而与Ⅰ、aVL导联的差异无统计学意义(P>0.05),3个胸导联中以V2导联的ST段变化最为明显；两个观测时点间各导联ST段升高的幅度差异无统计学意义(P>0.05)； V1、Ⅱ和aVF3个导联术后ST段升高的出现率低于V2、V5、Ⅰ和aVL导联(P<0.05),而这4个导联间出现率差异无统计学意义(P>0.05),两个观测时点间各导联的出现率差异无统计学意义(P>0.05)。75只雄性SD大鼠,共存活64只,经病理切片证实,50只大鼠出现心肌梗死病理表现(生理盐水组20只,甘蔗叶多糖组30只)。甘蔗叶多糖组左心室梗死面积小于生理盐水对照组,其差异均有统计学意义(P<0.05)。结论结扎大鼠LAD后胸导联ST段的变化更为明显,检测胸导联更能准确判断大鼠LAD闭塞后发生的心肌梗死。甘蔗叶多糖能缩小大鼠心肌梗死面积,提示对心肌具有保护作用。更多还原

【Abstract】 Background and ObjectivesMyocardial infarction (myocardial infarction, MI) is the current world-wide death and disability in one of the major diseases, and diagnosis and treatment of myocardial infarction has been the focus of the study. Myocardial infarction animal model is a necessary prerequisite for myocardial infarction experimental study. Ligation of the left anterior descending coronary artery (LAD) is a classic model of myocardial infarction preparation methods, and one of its key steps is to determine whether the model was successfully established. ECG has an important value for acute, evolving or new diagnosis of myocardial infarction, the diagnosis is based on ST segment deviation. ECG was widely used to diagnose MI in animal models during experimental study, and mostly limb leads were used, especially lead II, and some scholars had applied chest leads. Our previous study showed that ST-segment elevated in limb leads in less than80%rats with LAD ligation. Chest leads are in the horizontal plane, and face the anterior wall and lateral wall of the heart, the LAD occlusion causes anterior infarction, so chest leads can show myocardial infarction characteristic ECG changes after LAD occlusion, and should be more accurate than the limb leads, but we still have not seen in any relevant reports.Polysaccharide is made by many of the same or different aldose or ketose by A2or B2glycosidic bond with a wide range of biological activity of biological macromolecules, with the complexity of the biological activity and function, some researches suggested that some plant polysaccharides such as aspolysaccharides, aloe polysaccharides had a protective effect on myocardial infarction.In our previous study, a polysaccharide was successfully extracted from the sugar cane leaves. However, it is not known whether sugar cane leaves polysaccharide has a protective effect on myocardial infarction or not.In this study, rats were ligated the LADs, and simultaneously recorded9leads (limb leads+chest leads) ECG, and compared the accuracy between chest and limb leads in diagnostic of myocardial infarction in rats. These AMI rats were randomly divided into sugarcane leaf polysaccharide group and saline group. Sugarcane leaf polysaccharide solution was given to the polysaccharide group by gavage for5days; the control group was given normal saline at the same amount. On the sixth day after operation, the pathological sections of rat heart were made, and the left ventricular infarct area and left ventricular slice area were measured with the Image-Pro Plus6.0image measurement software.Methods75healthy male SD rats, after intraperitoneal anesthesia, the establishment of artificial ventilation and LAD ligation,9-lead ECG were recorded simultaneously in the rats before surgery and after30minutes,60minutes, measure the ST segment deviation and ST segment change rate except aVR.The MI rats were randomly divided into sugar cane leaf polysaccharide group and the saline group.24hours after the surgery, sugar cane leaf polysaccharide solution, normal saline were implementation of gavage treatment on the two experimental groups, continued5days and put to death. Heart drawn, separating the left ventricle, and is made biopsy of HE staining, measuring the area of left ventricular infarction, left ventricular slice area. Compare left ventricular infarct area/left ventricular slice area between two experimental groups, and analyzed statistically.ResultAfter30min,60min of LAD ligation, the elevation of ST segment in all leads is higher than before except III lead (P<0.05);The extent of ST elevation than before in Chest leads V2, V5is higher than all limb leads (P<0.05),V, is higher than Ⅱ, aVF (P<0.05), and is similar to I, aVL (P>0.05), the change of ST segment in V? is most obvious within the3chest leads; All leads have no obvious difference in30,60minutes (P>0.05); the frequencies of occurrences of ST elevation in V1, Ⅱ, aVF leads is lower than that in V2, V5, I, aVL (P<0.05), and these4leads have the same frequency (P>0.05). there is no obvious difference in frequencies of occurrences of ST elevation between tow time points (P>0.05).75male SD rats,64survived, confirmed by biopsy in50rats the pathology of myocardial infarction (saline group20, the sugarcane leaf polysaccharide group30). Sugarcane leaf polysaccharide group left ventricular infarct size, the percentage of infarction were less than the saline control group, the differences were statistically significant (P<0.05).ConclusionAfter ligation in rats LAD, ST-segment changes of chest lead are more obvious, the detection of chest lead determine the rat LAD occlusion occurred after myocardial infarction more accurately.The sugar cane leaf polysaccharide can narrow the area of myocardial infarction in rats, suggesting a protective effect on myocardial更多还原