组织多普勒心肌速度梯度评价胎儿心室动力学

Assessment of fetal myocardial dynamics by myocardial tissue Doppler velocity gradient

目的应用组织多普勒（tissue Doppler imaging，TDI）心肌运动速度梯度（myocardial velocity gradient，MVG）评价胎儿左、右心室心肌动力学。方法对孕龄22～40周的30例正常胎儿取横位四腔心切面进行组织多普勒成像，采集3个心动周期的动态图像，获得心肌速度分布图。测量左、右心室游离壁基底段心内膜和心外膜收缩期及舒张期峰值速度及心肌厚度，计算MVG。分析左、右心室心肌收缩期及舒张期心内膜、心外膜速度及MVG与孕周的关系。结果剔除图像质量较差的3例后，共有27例胎儿纳入分析。收缩期及舒张期左、右心室心内膜运动峰值速度均高于心外膜运动峰值速度（P〈0．01）。收缩期及舒张期左室游离壁、右室游离壁心肌运动速度与孕周呈正相关，而左室游离壁、右室游离壁MVG与孕周呈负相关。结论TDI技术测量MVG能够用于评价胎儿心室心肌动力学，可以了解胎儿心室壁运动速度在中、晚孕期的生理变化特点及规律，有助于更加准确可靠地评估胎儿心功能的相应变化。

Objective To evaluate the fetal myocardial dynamics by tissue Doppler imaging （TDI） myocardial velocity gradient（MVG）. Methods Thirty normal fetuses with a gestational age ranging from 22 to 40 weeks were studied. Two-dimensional color-TDI was superimposed on a transverse four-chamber view of the fetal heart and three cardiac cycles captured in cine-loop format. Generation of the suhepicardial and subendocardial myocardial velocity curves was realized by sampling two-dimensional color-TDI imaging,and myocardial thickness was calculated, subsequently the corresponding MVG were derived. The disparities between right and left subendocardial and subepicardial myocardial velocities in systole and diastole, and the relationship between fetal myocardial velocities,MVG and gestational weeks were correlated. Results Echocardiographic images from a total of 30 normal fetuses were analyzed for inclusion in this study,TDI velocities and MVG data from both the left and right ventricular free walls from 27 of them were of sufficient quality to make quantitative evaluation,3 fetuses with poor echocardiographic images were excluded. Fetal subendocardial myocardial velocities were higher than that of subepicardial myocardium throughout the cardiac cycle in both ventricular free walls. Right and left subendocardial and subepicardial myocardial velocities in systole and diastole showed a positive correlation with advancing gestational age. Right and left MVG in systole and diastole showed a negative correlation with advancing gestational age. Conclusions Tissue Doppler MVG evaluation of the fetal myocardial dynamics is feasible, illustration the relationship between fetal myocardial velocity, MVG and gestational weeks may offer a useful approach for better understanding the characteristic of fetal myocardial properties during fetal heart development.