左心室心肌透壁应变梯度的速度向量成像研究

Experimental validation of left ventricular transmural strain gradient with echocardiographic velocity vector imaging

目的:应用速度向量技术(VVI)定量分析健康成人及肥厚型心肌病患者左室心内膜下心肌(endo)、中层心肌(myo)、心外膜下心肌(epi)的应变梯度。方法:选取健康成人38例,肥厚型心肌病患者12例,应用VVI自动分析软件,计算心尖四腔切面的径向应变(RS)和三层心肌的纵向应变(LS)、左室短轴乳头肌水平切面的径向应变和每层心肌的环周应变(CS),以及相应的应变率(SR)、应变梯度。结果:健康成人及肥厚型心肌病患者内膜下心肌、心肌中层、外膜下心肌的纵向应变(LSendo、LSmyo、LSepi)、环周应变(CSendo、CSmyo、CSepi)均成递减的分布模式,相应的应变率(LSR、CSR)亦呈递减分布;肥厚型心肌病患者的三层心肌应变梯度(LSendo-epi、CSendo-epi、LSendo-myo、CSendo-myo、LSmyo-epi、CSmyo-epi)与正常人的差异无统计学意义;健康成人的心肌各层的纵向应变(LSendo、LSmyo、LSepi)及三层心肌纵向应变的均值(LSmean)均高于肥厚型心肌病患者;健康成人射血分数与四腔心切面的RS及LSendo、LSmyo及乳头肌水平短轴切面的RS、CSmyo相关。结论:健康成人及肥厚型心肌病患者心肌的各层LS和CS均保持一定规律,即内膜层>心肌中层>外膜层,这种应变梯度在肥厚型心肌病患者中与正常人无异;健康成人各层心肌的LS及LSmean均大于肥厚型心肌病患者;健康成人射血分数与四腔心切面的RS及LSendo、LSmyo及乳头肌水平短轴切面的RS、CSmyo相关,肥厚性心肌病患者这种相关性消失。

Objective：Application of velocity vector technology （VVI） quantitative analysis the strain gradient of left ventricular subendocardial myocardial （endo） , midmyocardium （myo） , subepicardium （epi） in health adults and patients with hypertrophic cardiomyopathy. Method： Thirty-eight healthy adults and twelve HCM patients were enrolled in this study. Application of VV1 automatic analysis software, we calculated radial strain （RS） and all three layers＇ longitudinal strain （I.S） in apical ＇i chamber view, RS and three layers＇ circumferential strain （CS） in short axis view at the level of papillary muscle, and the corresponding strain rate （SR）, strain gradient. Result： The I.S and CS of endo , mid-wall, and epimyocardium （LSendo, LSmyo, LSepi; CSendo, CSmyo, CSepi） both decreased gradually in healthy subjects and HCM patients, the corresponding longitudinal and circumferential SR also had this characteristic. The strain gradient difference of the three layers （LSendo epi, CSendo epi, LSendornyo, CSendo-myo, LSmyo-epi, CSmyo epi） between two subjects had no statistics significance. The LS of endo-, mid wall, epimyocardium and their mean value （LSmean） in healthy subjects were higher than those in HCM patients. The ejection fraction （EF） in heahhy subjects had a significant linear correlation with the RS, LSendo, LSmyo in apical 4 chamber view and RS, CSmyo in short axis view at the level of papillary muscle. Conclusion： There is a certain pattern in LS and CS gradient, which is inner strain〉mid-wall〉outer strain, and there is no apparent difference between heaithy subjects and HCM patients. Each layer myocardial LS and LSmean in healthy adults were all greater than those in HCM patients. The EF in healthy adults but not in HCM patients had a post tive correlation with RS, LSendo, LSmyo and CSmyo.