心肌应变率曲线评价心肌梗死局域舒张功能的实验研究

目的探讨急性心肌梗死后等容舒张期局域心肌的应变率特征及其应用价值.方法27条健康杂种犬,结扎冠状动脉左前降支近端.使用组织跟踪技术,分别采集结扎前和结扎后6 h连续3个完整心动周期的组织速度成像图,脱机分析左室18个节段长轴方向上心肌应变率曲线在等容舒张期的变化特征及其与病理解剖结果的关系.结果实验犬心肌梗死后受累节段局域等容舒张时间较正常节段相比明显延长（P＜0.05）;结扎前89%节段的局域等容舒张时间比整体等容舒张时间缩短;结扎后54%受累节段局域等容舒张时间较整体等容舒张时间延长,而只有10%的正常节段局域等容舒张时间较整体等容舒张时间延长（P＜0.01）.梗死区和相邻节段等容舒张期出现负向SR波.结论应变率成像能获得比传统方法更为丰富的心肌力与形变的信息,对评价局域心肌功能具有重要价值.

Experimental study of regional diastolic function during acute myocardial infarction by strain rate curves

Objective To evaluate whether strain rate curve can detect the festives of regional wall motion during isovolumic relaxation period after acute myocardial infarction,to analyze their clinical significance.MethodsThe left anterior descending coronary of 27 anaesthetic opened-chest dogs were ligated.Three complete cardiac cycles were stored in cineloop format of tissue velocity imaging before and after 6 hours of myocardial infarction.Left ventricular regional stain rate curves along long axis using digital workstation were obtained and the features of strain rate analyzed during isovolumic relaxation phase.Results The regional isovolumic relaxation time was significantly prolonged in coronary involved segments in comparison with normal segments (P<0.05).The regional isovolumic relaxation time was shorter than the global relaxation time in 89% of the segments before acute myocardial infarction.The regional isovolumic relaxation time in coronary involved segments was longer than the global relaxation time in 54% of the segments,while the regional isovolumic relaxation time in normal segments was longer than the global relaxation time only in 10% of the segments after acute myocardial infarction (P<0.01).Positive SR was replaced by negative SR near infarcted segments and infarcted segments during isovolumic relaxation period.Conclusions Strain rate is an objective index to evaluate biomechanics of left ventricular.It also can get rich information about stress and deformation compared with traditional methods.