二维斑点追踪技术评价兔急性心肌缺血早期左心房功能改变

Assessment of left atrial function in the early stage of acute myocardial ischemia using two-dimensional speckle tracking imaging

目的应用二维斑点追踪显像(2D-STI)技术评价兔急性心肌缺血早期左心房功能的变化,并探讨其与左心室整体纵向收缩峰值应变(PSLS)变化之间的关系。方法 48只大白兔行左冠状动脉前降支结扎,形成左心室局部心肌缺血,应用2D-STI技术测量缺血前后左心房各壁(前壁、下壁、间隔、侧壁、后壁)的收缩期、储器期、通道期峰值的应变及应变率(CT-PSR、R-PSR、CD-PSR),并计算其左心房整体平均应变和应变率(mCT-PSR、mR-PSR、mCD-PSR),同时应用2D-STI技术测量左心室16节段纵向收缩应变,计算左心室整体PSLS。结果最终46只大白兔均成功建立急性心肌缺血模型。与缺血前比较,缺血后左心房在通道功能期和储器功能期的平均峰值应变均降低(P﹤0.05),在泵功能期的平均峰值应变有所增加。缺血后左心房mCT-PSR、mR-PSR、mCD-PSR均降低(P﹤0.05),左心室整体PSLS也降低(P﹤0.05),且其缺血前后变化率与左心房mCT-PSR、mR-PSR、mCD-PSR变化率呈正相关(r=0.34、0.49、0.38,P=0.022、0.001、0.01)。结论 2D-STI技术评价急性心肌缺血早期左心房功能变化是可行的,急性心肌缺血早期左心室整体PSLS及左心房各期平均峰值应变率均降低,左心室纵向收缩应变的变化会影响左心房的功能,表现为左心房各应变参数的改变。

Objective To evaluate the changes of left atrial （LA）function in the early stage of acute myocardial isehemia using two-dimensional speckle tracking imaging （2D-STI）, and to explore the relationship between the changes of LA function and left ventricular（ LV ） global longitudinal systolic peak strain （PSLS）.Methods In 48 healthy rabbits, the left anterior descending coronary artery was occluded to cause LV regional acute ischemia.The peak strain and strain rate values of the left walls during the contractile, reservoir, and conduit phases （CT-PSR, R-PSR, CD-PSR ）, as well as the longitudinal systolic strain of LV 16 segments were measured before and after ischemia using 2D-STI.The LA global mean peak strain and strain rates （mCT- PSR, mR-PSR, mCD-PSR）, and LV global PSLS were calculated.Results mCT-PSR, mR-PSR and mCD-PSR values of LA decreased after ischemia（ P 〈 0.05 ）.LV global PSLS decreased after ischemia（ P 〈 0.05 ）and its percent change was positively correlated with the percent changes of LA mCT-PSR,mR-PSR and mCD-PSR（r=0.34,0.49 and 0.38;P=0.022,0.001 and 0.01 ）. Conclusion 2D-STI can be used to evaluate the changes of LA function in the early stage of acute myocardial ischemia.In the early stage of acute myocardial ischemia, LV global PSLS and LA mCT-PSR, mR-PSR, mCD-PSR decreased.The change of LV global PSLS can affect left atrial function, showing the change of the LA strain parameters.