组织强度曲线评价急性心肌梗死犬左室局域舒张功能的实验研究

目的：探索急性心肌梗死（AMI）犬左室舒张期局域心肌组织强度变化特点，为组织强度应用于临床判断急性心肌梗死病人的左室局域舒张功能提供依据。方法：对12只犬冠状动脉左前降支结扎前基础状态及结扎后4h左室心肌进行组织多普勒成像检查。记录心尖二腔动态图像，应用组织强度一时间曲线（TIC）获取左室各节段心肌同步组织TIC，测量等容舒张期、心室充盈期局域心肌组织强度值及其变化幅度，对两组结果进行对比分析。结果：冠状动脉结扎前基础状态，整个舒张期组织强度自心底至心尖呈负值增大梯度变化，结扎后4h该规律消失，梗死节段组织强度（dB）负值明显增大。基础状态TIC的等容舒张期由向上波群组成，AMI后等容舒张期由水平或向下波群构成，dB负值明显增大。心室充盈期梗死部位dB负值明显增大，与基础状态相比差异具有显著性，梗死部位与非梗死部位的dB值相比差异具有显著性（P〈0．01）。结论：AMI时，心肌组织dB负值增大，通过定量分析心肌组织强度变化，不但能区别正常和梗死部位，同时可以评估心肌组织的舒张功能，对临床早期诊断AMI和定位梗死部位有重要的应用价值。

EVALUATION OF REGIONAL DIASTOLIC FUNCTION IN DOGS WITH ACUTE MYOCARDIAL INFARCTION BY TISSUE INTENSITY CURVE

Objective:To detect the tissue intensity features of regional wall abnormalities in dogs with acute myocardial infarction during diastolic period,and the results from this study provide experimental foundation for tissue intensity cure(TIC) in estimating the regional left ventricular diastolic function of acute myocardial infarction.Methods:Twelve dogs ligated left anterior descending coronary artery(LADCA) were performed at apical two-chamber view by doppler tissue imaging in pre-ligation and post-ligation 4 hours.Tissue intensity of LV segments was analyzed by tissue intensity curves synchronously.Results:Pre-ligation TIC showed increasing negative value from base to apex during the whole relaxation period;in post-ligation 4 hours,this law disappeared and the negative value of dB in infarction segments was bigger than that of pre-ligation.During ventricular filling phase post-ligation the value of dB of infarction segment was bigger than pre-ligation and non-infarction segment(P<0.01).Conclusion:The dB value of myocardial tissue increases during acute myocardial infarction(AMI).The infarction and normal myocardium can be distinguished and assessed by quantitatively analyzing the change of tissue intensity.And TIC is very useful for clinical diagnosing acute myocardial infarction and positioning the segment of infarction.