Objective To evaluate the changes of left ventricular torsion (LVT ) and the relationship between LVT and systolic function in canine after apex ischemia with two-dimensional speckle tracking imaging , and to explore the roll of apex in left ventricular systolic function . Methods Left ventricular apex ischemia was induced in 14 open-chest dogs after left anterior descending artery occlusion near for 1 h . Two-dimensional gray-scale images were collected on left ventricular short axis in the continuous 3-5 cardiac cycles before and after occlusion , respectively . The left ventricular pressure curve was recorded simultaneously . Differences of apical and basal segment rotation and left ventricular torsion angle bef'ore and after apex ischemia were compared , and the relationship between LVT and systolic function was analyzed . Results After occlusion , LVT decreased ohviously ( P＜0. 05 ) . Rotation of apical segment reduced and the ahsolute value of basal segment increased (both P＜0. 05 ) . LVT was positively correlated with +dp/dtmax ( r= 0. 68 , P＜O. 001) . Conclusion The rotation of apical segment and LVT reduce significantly after apex ischemia , which lead to the decrease of left ventricular systolic function , indicating that apex plays an important role in left ventricular systolic fumition .%目的 应用二维斑点追踪显像评价犬心尖部心肌缺血前后左心室扭转角度变化及其与左心室收缩功能的关系,探讨心尖对左心收缩功能的作用.方法 14只犬开胸后阻断前降支近心尖部1 h,造成左心室心尖部心肌缺血.连续采集阻断前后各3～5个心动周期左心室短轴切面二维灰阶图像,同步记录左心室压力曲线.比较心尖部心肌缺血前后心尖段、基底段旋转角度及左心室整体扭转角度的差异,分析左心室扭转与左心室收缩功能的关系.结果 犬心尖部心肌缺血后,左心室整体扭转角度显著减低(P＜0.05),左心室心尖段旋转角度减小,基底段旋转角度绝对值增大(P均<0.05).左心室扭转角度与+dp/dtmax呈正相关(r=0.68,P＜0.001).结论 犬心尖部心肌缺血后左心室心尖段旋转角度及左心室整体扭转角度明显减低,引起收缩功能减退,提示心尖在左心室收缩功能中起重要作用.
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