斑点追踪成像技术评价心室起博对左心室壁运动影响的实验研究

目的 应用斑点追踪成像技术(STI)观察评价心室起搏对左室室壁运动的影响.方法 7只成年猪在全麻成功后切开胸骨及心包,暴露出心脏.将起搏器电极放在心外膜上行左室或右室起搏,并在起搏前后采集左室中段短轴切面超声图像.用STI软件对图像进行环向应变分析并得出时间应变曲线.以QRS波作为心动周期的起点,分析起搏前后的心肌收缩起始时间、终止时间及收缩总时间占整个心动周期的比率,并了解左室壁各节段收缩协调情况.结果 与窦性心律相比,所有心室起搏心律的收缩起始时间、终止时间及收缩总时间占整个心动周期的比率均增大.心室起搏可导致室壁各节段运动明显不协调.当起搏心率＞130次/min时,在起搏心电图正常情况下,左室整体及部分节段在一个心动周期中出现一次以上的收缩或舒张运动,并出现在相邻的几个心动周期中收缩幅度变异性很大情况.结论 心室起搏可引起左室收缩延迟及时间延长,并可引起左室室壁各节段运动不协调.高频率心室起搏还可能引起左室室壁不规则运动.

Abstract：

Objective To assess the change of left ventricular wall motion at ventricular pacing(VP)by using global circumferential strain (GCS) and segmental circumferential strain of speckle tracking imaging(STI). Methods Seven adult pigs were sedated,followed by median sternotomy and opening of the pericardium. Temporary pacing leads were placed on the right ventricular (RV) epicardium and LV epicardium for RV or LV pacing. A LV short axis view at the mid-level LV was acquired at sinus and VP rhythm. Analysis of circumferential strain by STI was performed offline. The onset of QRS wave was used to characterize the beginning of the cardiac cycle, and the ratio of beginning systolic time, end systolic time and total systolic time to cardiac cycle dyssynchrony was analyzed at sinus and VP rhythm. Results Compared with sinus rhythm,in VP rhythm all of the ratio of the beginning systolic time,end systolic time and total systolic time to cardiac cycle were increased (all P ＜0.05), and the construction of six segments were dyssynchrony,even segmental paradoxical movement. At VP ≥130 beats/min,both LV global and LV segments sometimes showed irregular motion while the EKG remained normal, which included: ( 1 ) multiple construction and diastole in one heart cycle; (2) A large variability of construction amplitude in several consecutive cardiac cycles. Conclusions VP can lead to several kinds of disturbance of left ventricular wall motion, including delay and lengthening of LV systole, dyssynchrony, and irregularity of systole and diastole.

Animal experimental study of left ventricular wall motion at ventricular pacing by speckle tracking imaging

Objective To assess the change of left ventricular wall motion at ventricular pacing(VP)by using global circumferential strain (GCS) and segmental circumferential strain of speckle tracking imaging(STI). Methods Seven adult pigs were sedated,followed by median sternotomy and opening of the pericardium. Temporary pacing leads were placed on the right ventricular (RV) epicardium and LV epicardium for RV or LV pacing. A LV short axis view at the mid-level LV was acquired at sinus and VP rhythm. Analysis of circumferential strain by STI was performed offline. The onset of QRS wave was used to characterize the beginning of the cardiac cycle, and the ratio of beginning systolic time, end systolic time and total systolic time to cardiac cycle dyssynchrony was analyzed at sinus and VP rhythm. Results Compared with sinus rhythm,in VP rhythm all of the ratio of the beginning systolic time,end systolic time and total systolic time to cardiac cycle were increased (all P ＜0.05), and the construction of six segments were dyssynchrony,even segmental paradoxical movement. At VP ≥130 beats/min,both LV global and LV segments sometimes showed irregular motion while the EKG remained normal, which included: ( 1 ) multiple construction and diastole in one heart cycle; (2) A large variability of construction amplitude in several consecutive cardiac cycles. Conclusions VP can lead to several kinds of disturbance of left ventricular wall motion, including delay and lengthening of LV systole, dyssynchrony, and irregularity of systole and diastole.