二维斑点追踪成像技术定量评估捆绑应激模型大鼠左心室心肌运动及功能动态变化

Quantitative evaluation of left ventricular function in immobilization stress model of rats with two-dimensional speckle tracking echocardiography

目的应用二维斑点追踪技术评估捆绑应激模型大鼠左心室心肌运动及功能的动态变化。方法将48只30周龄雌性Sprague Dawley大鼠完全随机分为观察组（36只）和对照组（12只）。再将观察组完全随机分为4个亚组：应激后即刻亚组、应激后24 h亚组、应激后48 h亚组、应激后72 h亚组，各 9只。将36只观察组大鼠同时进行捆绑应激30 min，对照组大鼠置于笼中自由活动。应激后除应激后即刻亚组即刻进行超声心动图检查外，其余应激亚组大鼠均放回笼中，分别于24、48、72 h后进行超声心动图检查。M型超声测量舒张末期室间隔厚度、左心室后壁厚度、左心室舒张末期内径（LVEDD），左心室收缩末期内径（LVESD）、左心室射血分数、缩短分数、每搏输出量（SV）、左心室收缩末期容积、左心室舒张末期容积。留存胸骨旁左心室长轴切面（前间隔基底段、中间段、心尖段，后壁基底段、中间段、心尖段）和乳头肌水平短轴切面（前壁、侧壁、后壁、下壁、后间隔、前间隔）图像，脱机分析12个节段的径向应变、径向应变率、径向收缩峰值速度、纵向应变、纵向应变率、纵向收缩峰值速度、圆周应变、圆周应变率。结果观察组大鼠出现不同程度心电图异常，9只出现ST段明显抬高［25.0%（9/36）］。二维超声探及左心室心尖部室壁运动减低并向外膨隆1只。应激后24 h亚组LVESD明显低于应激后72 h亚组，LVEDD、SV明显低于对照组和应激后48 h亚组［（3.76±0.82）mm比（4.37±0.58）mm，（7.40±0.61）mm比（7.81±0.39）、（7.99±0.27）mm，（228±41）ml比（260±36）、（265±26）ml］，差异均有统计学意义（均P＜0.05）。各组其余心脏功能参数指标比较，差异无统计学意义（P〉0.05）。应激后即刻亚组前间隔心尖段径向应变、径向应变率、径向收缩峰值速度、纵向应变、纵向应变率、纵向收缩峰值速度和后壁径向应变、径向应变率、圆周应变、圆周应变率均低于对照组［（19.36±5.75）%比（37.31±9.97）%、（3.67±1.67）s^-1比（7.18±204）s^-1、（0.65±0.44）cm/s比（1.21±0.41）cm/s、（-14.63±6.98）%比（-25.43±2.07）%、（-3.33±0.67）s^-1比（-6.31±0.96）s^-1、（0.54±0.34）cm/s比（1.04±0.88）cm/s、（21.27±8.16）%比（44.40±7.86）%、（5.02±0.89）s^-1比（8.24±0.48）s^-1、（-16.91±8.08）%比（-24.27±9.49）%、（-4.21±0.46）s^-1比（-7.00±0.80）s^-1］，差异均有统计学意义（均P＜0.05）。结论应激后左心室壁部分节段出现可逆性收缩功能减低。二维斑点追踪成像技术能够较常规超声更早、更敏感地检测捆绑应激大鼠早期左心室室壁运动及功能异常。

ObjectiveTo quantitatively evaluate the left ventricular function in immobilization stress （IMO） model of rats with two-dimensional speckle tracking echocardiography technique. MethodsForty-eight female Sprague Dawley rats （aged 30 weeks） were randomly divided into observation group （n=36） and control group （n=12）; the rats in observation group were further randomly divided into instant, 24 h, 48 h, 72 h subgroup （n=9 in each group）. IMO model was established by binding for 30 min in observation group, and the rats in control group were free movement. Echocardiography was performed immediately, 24 h, 48 h and 72 h after relief of stress in each subgroup. The interventricular septal thickness, left ventricular posterior wall thickness, left ventricular end diastolic dimension （LVEDD）, left ventricular end systolic dimension （LVESD）, left ventricular ejection fraction, fractional shortening, stroke volume （SV）, end-systolic volume and left ventricular end-diastolic volume were determined; the images of left ventricular long axis plane （base, mid, apex of anterior septum and posterior wall） and left ventricular short axis plane （anterior wall, lateral wall, posterior wall, inferior wall, posterior septum, anterior septum） were saved, the radial strain and strain rate, longitudinal strain and strain rate, circumferential strain and strain rate, systolic peak velocity of 12 segments were analyzed with two-dimensional speckle tracking echocardiography. ResultsThe different degree of abnormalities in the electrocardiogram were observed in all the animals in observation group, with obvious ST segment elevation in 9 rats [25.0% （9/36）]. Left ventricular apex regional wall motion dysfunction occurred in 1 rats in echocardiography. The LVESD in 24 h subgroup was significantly lower than that in 72 h subgroup [（3.76±0.82） mm vs （4.37±0.58） mm], the LVEDD and SV in 24 h subgroup were significantly lower than those in control group and 48 h subgroup [（7.40±0.61） mm vs （7.81±0.39）, （7.99±0.27） mm; （228±41） ml vs （260±36）, （265±26） ml] （P〈0.05）; the other heart function indexes were not significantly different among groups （P〉0.05）. The radial strain, strain rate and systolic peak velocity, the longitudinal strain, strain rate and systolic peak velocity of apex section in anterior septum, the radial strain and strain rate, the circumferential strain and strain rate of posterior wall in instant subgroup were significantly lower than those in control group [（19.36±5.75）% vs （37.31±9.97）%, （3.67±1.67） s^-1 vs （7.18±2.04） s^-1, （0.65±0.44） cm/s vs （1.21±0.41） cm/s, （-14.63±6.98）% vs （-25.43±2.07）%, （-3.33±0.67） s^-1 vs （-6.31±0.96） s^-1, （0.54±0.34） cm/s vs （1.04±0.88） cm/s, （21.27±8.16）% vs （44.40±7.86）%, （5.02±0.89） s^-1 vs （8.24±0.48） s^-1, （-16.91±8.08）% vs （-24.27±9.49）%, （-4.21±0.46） s^-1 vs （-7.00±0.80） s^-1] （P〈0.05）. ConclusionsReversible segmental contraction dysfunction occurres on partial segments of left ventricular wall after stress in IMO rats, which can be detected by speckle tracking echocardiography more early and sensitively compared with M model echocardiography.