定量组织速度成像检测不同程度缺血心肌局部收缩功能

目的　应用定量组织速度成像 (QTVI)技术检测不同程度心肌缺血时的左心局部收缩功能的变化 ,并探索评价缺血心肌收缩功能的新指标。方法　将 15只开胸犬左前降支 (L AD)血流减少造成中度、重度心肌缺血模型。以 QTVI观察左室前壁基底段、中间段、心尖段在不同程度缺血时等容收缩期、收缩早期心肌组织峰值速度 (Vivc、 Vs1 )和收缩中期速度 (Vs2 )的变化。结果　 Vivc由基础状态时以正向波为主变为中重度缺血时以负向波峰为主 ,变化具有显著意义 (P<0 .0 5 )。缺血导致 Vs1 迅速显著地降低 (P<0 .0 1)。 Vs2 随缺血也有所减低 ,但部分节段变化不明显 (P>0 .0 5 )。结论　 Vivc和 Vs1 是定量评价缺血心肌收缩功能的最佳指标 ,QTVI可以敏感、准确评价不同程度心肌缺血时局部心肌收缩功能。

Detection of Regional Myocardial Systolic Function in Graded Coronary Stenosis in Dogs Using Quantitative Tissue Velocity Imaging

Objective:To quantify regional myocardial systolic function during acute different graded ischemia using quantitative tissue velocity imaging (QTVI),and to find out the new measurements of function in ischemic myocardium.Methods:Two grades of moderate and severe ischemia were produced in 15 open-chest canine models by partial ligation of left anterior descending coronary artery. The left ventricular wall on the two-chamber view was divided into 6 segments (base,middle,and apical segments along the anterior and inferior walls). The largest absolute velocity during isovolumic contraction (Vivc),the peak velocities during early-ejection (Vs 1) and mid-ejection velocities (Vs 2) in each segment were determined.Results:In the anterior wall,The Vivc was dominantly positive in all segments at baseline.With onset of moderate and severe ischemia,the Vivc was decreased and became dominantly negative (P<0.05).After ischemia,Vs 1 was decreased rapidly and significantly (P<0.01).There was a decrease in Vs 2,but in some segments,it was not obvious (P>0.05).In the nonischemic inferior wall,Vivc,Vs 1 and Vs 2 showed no significant changes(P>0.05).Conclusions:Vivc and Vs 1 are the best markers of systolic function in ischemic myocardium.QTVI may be a promised new tool for quantifying ischemia-induced regional myocardial dysfunction.