实时三维超声对慢性心肌缺血负荷前后左心室收缩同步性的实验研究

目的 应用实时三维超声心动图技术探讨慢性心肌缺血左心室收缩同步性的改变,以及小剂量多巴酚丁胺负荷对左室收缩同步性的影响.方法 应用Philips iE33对10只猪于建模前及建模后4～6周每周行负荷前后心脏实时三维超声检查.建模前正常猪归为对照组;建模后依照冠脉狭窄程度分为轻度狭窄组、中度狭窄组和重度狭窄组.用3DQA软件分析左室多节段间达最小容积时间(Tmsv)的最大差值(Tmsv-Dif)、标准差(Tmsv-SD)及其标化值.结果 中重度狭窄组负荷后12节段间、6节段间、基底段侧壁与下壁及后间隔间Tmsv最大差值之标化值较负荷前升高;静息及负荷后重度狭窄组各同步化参数较对照组、轻度狭窄组增大,中度狭窄组对照组增大,差异均有统计学意义(P＜0.05).轻度狭窄组负荷后6节段、基底段侧壁与下壁和后间隔间Tmsv最大差值较对照组升高,其标化值静息及负荷后均较对照组升高,差异有统计学意义(P＜0.05).结论 实时三维超声心动图结合负荷试验能较敏感地显示慢性缺血导致的左室收缩同步性异常,左旋支供血区的侧壁比正常供血的室壁改变更明显.

Quantitative assessment of left ventricular systolic synchrony before and after stress in chronic ischemic model by real-time three-dimensional echocardiography

Objective To assess the left ventricular systolic asynchronicity in chronic ischemic model with real-time three-dimensional echocardiography (RT-3DE), and to explore the affection of low-dose dobutamine to it. Methods A chronic ischemic model was induced by placing an Ameroid constrictor in the left circumflex(LCX) in swines,then full volume RT-3DE was performed by Philips iE33 with X3-1 probe combining rest and stress(dobutamine stress echocardiography, DSE) every week after LCX constriction.Ten normal pigs before operation served as controls (group A). Examination of all the models post operation were grouped into group B (mild stenosis, LCX stenosis＜50% ), group C (moderate stenosis, LCX stenosis 50%～75%) and group D (severe stenosis, LCX stenosis≥75%) according to the results of coronary angiography. Images were copied to QLAB 5.2 postprocess workstation,and 3DQA software was used to analyze the full volume data sets. The time to the point with minimal systolic volume (Tmsv) in each segment was taken to derive the following indexes of systolic synchrony: the maximum difference of Tmsv (Tmsv-dif) and standard deviation(Tmsv-SD) among various segments and standard index (Tmsv-dif% and Tmsv-SD%), to evaluate left ventricular dyssynchrony. Tmsv3-6 represented the maximum difference of Tmsv between lateral segment and posterior septum (Tmsv3-5: between lateral segment and inferior) in basal level. Results Tmsvl2-Dif%, Tmsv6-Dif%, Tmsv3-6% and Tmsv3-5% under stress condition in group C and D were significantly higher than those at rest;all the data in group D were significantly higher than in group A and B, and in group C higher than group A ( P ＜0.05,0.01 ). Compared with group A,Tmsv6-Dif,Tmsv3-6 and Tmsv3-5 in group B were significantly increased under stress condition,and so did their standardize data under both rest and stress conditions ( P ＜ 0.05, 0. 01 ). Conclusions RT-3DEcombined with DSE could display sensitively the left ventricular asynchrony caused by chronic ischemia,and that will be more significant in lateral wall in LCX stenosis than in normal segments.