超声对比格犬急性心肌缺血左心室三维位移的研究

目的观察健康比格犬左心室心肌三维峰值位移(3D-D)、位移达峰时间(3D-DTC)以及位移同步化指数(3D-DTSD)变化,量化评价左心室基础状态与急性心肌缺血状态心肌力学状态特征。方法建10只健康比格犬开胸模型,结扎左冠状动脉左前降支,诱导产生急性心肌缺血,分别采集基础状态和急性缺血状态每一状态下一个完整心动周期的全容积实时灰阶图像。应用斑点跟踪成像技术测量左心室心肌基础状态和急性缺血状态3D-D、3D-DTC,并计算出3D-DTSD,分析心肌基础状态和急性缺血状态3D-D的时序分布规律。结果 (1)急性心肌缺血状态与基础状态比较左心室各节段心肌3D-D均呈下降趋势,其中急性心肌缺血状态左心室心肌底前间隔、中前间隔、中间隔、尖前壁、尖间隔3D-D分别为(2.464±0.624)、(2.526±1.205)、(2.770±1.082)、(1.627±0.935)、(1.866±1.150)mm,基础状态的以上部位3D-D分别为(3.722±1.280)、(4.176±1.567)、(4.127±1.429)、(2.897±1.062)、(3.413±1.565)mm,两者比较差异有统计学意义(t=2.785、2.815、2.320、3.542、2.997,P均<0.05)。(2)急性心肌缺血状态底前壁、底前间隔、底间隔、底下壁、底后壁、底侧壁、中前壁、中前间隔、中间隔、中下壁、中后壁、中侧壁、尖前壁、尖间隔、尖下壁、尖侧壁3D-DTC分别为(325.43±78.26)、(339.21±65.81)、(347.59±86.21)、(304.27±112.34)、(296.58±114.52)、(306.18±57.17)、(342.82±79.68)、(351.63±84.21)、(332.55±171.15)、(336.66±169.53)、(304.09±87.56)、(329.07±107.62)、(435.25±66.99)、(400.48±149.48)、(375.92±190.36)、(352.46±86.38)ms,基础状态的以上部位3D-DTC分别为(228.00±64.50)、(194.49±50.81)、(193.50±72.52)、(235.26±74.76)、(213.98±85.46)、(221.38±70.44)、(233.78±69.31)、(224.19±10.40)、(193.95±66.42)、(214.17±60.66)、(220.90±61.83)、(253.59±65.13)、(246.71±79.47)、(240.38±60.66)、(248.56±47.58)、(253.93±73.59)ms,急性缺血状态与基础状态比较左心室各节段心肌3D-DTC均发生明显延迟,除底下壁、中下壁、尖下壁和中侧壁外,余节段差异有统计学意义(t=4.601、4.517、6.516、2.620、2.857、2.868、4.745、2.708、2.652、7.469、3.345、3.004,P均<0.05)。(3)急性心肌缺血状态与基础状态比较左心室心肌3D-DTSD增大,差异有统计学意义(68.29±22.18,50.28±20.30,t=2.582,P<0.05)。结论实时三维峰值位移作为终点力学参数能够敏感地反映急性心肌缺血状态左心室异常的结构和力学状态,有助于深入揭示急性心肌缺血后左心室的运动状态。

Echocardiographic study of left ventricular 3-dimensional displacement in canine models of acute myocardial ischemia

Objective To evaluate the changes of left ventricular myocardial 3-dimensional peak displacement(3D-D),3D-DC peak time(3D-DTSD) and the standard deviation of TC(3D-DTSD) between baseline and acute ischemia.To provide a reliable mechanical database for myocardial structure and function observation.Methods Left anterior descending coronary(LAD)artery was ligated to induce acute myocardial ischemia in open-chest Beagle canine models(n=10).3D full volumetric real-time imaging was acquired in a complete cardiac cycle.With speckle tracking imaging,the 3D-D,3D-DTC and 3D-DTSD were calculated andanalyzed before and after acute myocardial ischemia.Results(1)Compared with baseline levels,the 3D-D significantly decreased after acute myocardial ischemia in all segments:(3.722±1.280)mm vs(2.464±0.624)mm in basal anteriorspetal segment(t=2.785,P<0.05),(4.176±1.567)mm vs(2.526±1.200) mm in mid anteriorspetal segment(t=2.815,P<0.05),(4.127±1.429)mm vs(2.770±1.082)mm in mid spetal segment(t=2.320,P<0.05),(2.897±1.062)mm vs(1.627±0.935)mm in apical anterior segment(t=3.542,P<0.05),and(3.413±1.565)mm vs(1.866±1.150)mm in apical spetal segment(t=2.997,P<0.05).(2) After adjusting with the heart rate,the myocardial 3D-DTC of most segments after acute myocardial ischemia were(325.43±78.26),(339.21±65.81),(347.59±86.21),(304.27±112.34),(296.58±114.52),(306.18±57.17),(342.82±79.68),(351.63±84.21),(332.55±171.15),(336.66±169.53),(304.09±87.56),(329.07±107.62),(435.25±66.99),(400.48±149.48),(375.92±190.36),(352.46±86.38)ms.And the myocardial 3D-DTC of most segments at baseline were(228.00±64.50),(194.49±50.81),(193.50±72.52),(235.26±74.76),(213.98±85.46),(221.38±70.44),(233.78±69.31),(224.19±10.40),(193.95±66.42),(214.17±60.66),(220.90±61.83),(253.59±65.13),(246.71±79.47),(240.38±60.66),(248.56±47.58),(253.93±73.59)ms.Therefore,the myocardial 3D-DTC after acute myocardial ischemia were significantly longer than those at baseline for most segments(t=4.601,4.517,6.516,2.620,2.857,2.868,4.745,2.708,2.652,7.469,3.345,3.004,all P<0.05),except for basal interior,mid interior,apical interior and mid lateralsegments.(3)There was a significant difference in 3D-DTSD between baseline(50.28±20.30) and acute myocardial ischemia state(68.29±22.18,t=2.582,P=0.036).Conclusions The myocardial 3D-D could be used as a terminal mechanical parameter to evaluate the abnormal structure and mechanics of left ventricle and then to reveal the changes of left ventricle movements after acute myocardial ischemia.