超声三维斑点追踪评价不同心脏起搏方式对健康犬左心室功能的影响

Ultrasonic 3D speckle tracking for assessment the effects of various cardiac pacing modes on left ventricular function of healthy canine

目的探讨超声三维斑点追踪成像技术评价不同心室位点心脏起搏对健康犬左室壁机械同步性和左室功能的影响。方法分别采集10只健康开胸比格犬基础状态和右室心尖、左室心尖、左室侧壁起搏状态一个完整心动周期的左心室全容积实时图像；同步记录左室压力时间变化曲线并获取左室射血压力和收缩期压力最大上升速率。用超声三维斑点追踪分析软件分别提取不同状态左室壁径向三维应变图、左室壁径向三维峰值应变和左室收缩末期容积、舒张末期容积、射血分数、每搏输出量、心输出量。定性观察并比较不同状态左室壁各节段心肌的径向三维应变同步性。对定量参数进行配对t检验、卡方检验和直线相关分析。结果①左室心尖或侧壁起搏状态左室壁各节段心肌的径向三维应变不同步程度较右室心尖起搏状态明显。②左室心尖或侧壁起搏状态左室壁径向三维峰值应变显著减低的心肌节段数多于右室心尖起搏状态（9／16对2／16，P〈0．05）。③左室心尖或侧壁起搏状态左室壁整体径向三维峰值应变和左室每搏输出量、射血分数、心输出量均低于右室心尖起搏状态（P〈0．05）。④不同状态左室壁整体径向三维峰值应变分别与左室每搏输出量、射血分数、心输出量呈线性正相关（r=0．781～0．984，P〈0．05）。结论左室心尖或侧壁起搏对健康犬左室壁机械同步性和左室功能的损害超过右心室心尖起搏。

Objective To evaluate the effects of various cardiac pacing modes on mechanical synehrony of left ventricular wall and left ventricular function using ultrasonic 3D speckle tracking imaging. Methods Ten healthy open-chest beagles left ventricular full volumetric real-time imaging in a completed cardiac cycle were acquired respectively during baseline（BASE） and right ventricular apex pacing（RVAP）, left ventricular apex pacing（LVAP）, left ventricular lateral wall pacing（LVLP） state. Left ventricular pressure time sequence curve was recorded simultaneously for achieving left ventricular ejection pressure and the maximal upstroke velocity of left ventricular systolic pressure. Radial 3D strain maps and radial 3D peak strain of left ventricular wall, and left ventricular end systolic volume, end diastolic volume, stroke volume, ejection fraction, cardiac output of different states were extracted respectively using ultrasonic 3D speckle tracking analysis software. The radial 3D strain synchrony of left ventricular wall during different states was qualitatively observed and compared. The t test, chi square test and linear correlation analysis was applied respectively for analyzing the quantitative parameters. Results ①The radial 3D strain asynchrony of different myocardial segments of left ventricular wall during LVAP or LVLP was worse than that during RVAP. ② There were more myocardial segments of left ventrieular wall which radial 3D peak strain degraded significantly during LVAP or LVLP than those during RVAP （9/16 vs 2/16, P 〈0.05）. ③To be compared with RVAP, left ventrlcular stroke volume, ejection fraction, cardiac output and the global radial 3D peak strain of left ventricular wall were degraded during LVAP or LVLP（ P 〈0.05）. ④ There were statistic significant linear correlations between the global 3D peak strain of left ventricular wall and left ventricular stroke volume,and left ventricular ejection fraction,and cardiac output in different states（ r = 0. 781 0. 984, P 〈0.05）. Conclusions As far as the destructive effect on the mechanical synchrony of left ventricular wall and left ventricular function of healthy canine is concerned, LVAP or LVLP mode is more harmful than RVAP mode.