应变率成像在胎儿房性心律失常诊断中应用的初步探讨

目的探讨应用速度向量成像（VVI）技术对胎儿房性心律失常时心肌结构力学及形变学影响的应变与应变率研究，评价胎儿心律失常时对心肌应激状态、运动传导就及功能的影像。方法对检出的77例胎儿心律失常（其中室上性心动过速（SVT）12例、65例为频发性房性早搏（PAC））进行VVI成像技术分析，检测心律失常时胎儿心肌运动速度向量变化及对应变与应变率影响，对照组80例心率正常胎儿。结果胎儿SVT12例中7例持续发作48h者治疗前心室率250—310bpm，均合并心衰及出现水肿，VVI速度向量振幅明显降低，其应变与应变率明显低于对照组（P〈0．01）；阵发一陛SVT5例VVI速度向量振幅-过性降低，心肌应变与应变率无变化；频发PAC组示早搏时速度向量振幅改变，且运动方向同步，心肌运动三维数据定量可显示旱搏及代偿间期的三维模式，应变与应变率与对照组无差异（P〉0．05）。结论VVI成像通过心律失常心肌结构力学变化解析胎儿心律失常，特别是对胎儿心动过速时的快速心率可进行实时动态分析。及应用M型扫描法确认心动周期使胎儿心肌应变与应变率分析成为可行。

Preliminary studios of strain and strain rate application in fetus with arrhythmia

Objective： To study the cardiac structural mechanics and hemodynamics in fetus with arrhythmia by Velocity Vector Imaging （VVI） technology, and to evaluated this new technology in the determination of myocardial stress, conduct sequence and cardiac function in fetus with arrhythmia. Methods： 77 fetus with arrhythmia and 80 healthy individuals were enrolled, arrhythmias included 12 supraventricular tachycardia （SVT） and 65 frequently premature atrial contractions （PAC）, VVI was used to determinate fetus＇s myocardial mechanics, strain and strain rate. Results： 7 of 12 fetus suffered from persistant SVT for more than 48h before effective treatment, heart rate ranged from 250 -310 and complication of cardiac failure and edema occurred, and VVI revealed that amplitude of velocity was significantly reduced, with low strain and strain rate compared with controls （ P 〈 0. 01 ） ; in the other SVT fetus＇, reduction of amplitude of velocity was seen but no change of strain rate occurred. In fetus with PAC. VVI found asynchronous motion without lowing of velocity amplitude ; three - dimensional color mmode analysis established the three - dimensional pattern of premature beats and compensatory pause, and strain and strain rate were found unchanged in compared with controls （ P 〉 0. 05）. Conclusion： VVI could be used to evaluate the cardiac structural mechanics by quantitatively analyzing strain and strain rate, and could precisely provide evidence for diagnosis of cardiac dysfunction in fetus with arrhythmia when ECG is still not feasible.