Study on fetal circulation using Doppler signal and pulse waveforms

(1)胎儿等容量收缩时间的研究：为了研究正常妊娠和合并胎盘血管疾病的复杂妊娠胎儿心脏等容量收缩时间（ICT），我们测量了160例正常妊娠和55例复杂妊娠的胎儿心脏等容量收缩时间。在正常妊娠中，ICT随妊娠期和胎儿心率保持不变。ICT持续时间延长与围产期异常之间存在很强的相关性，表明在胎盘血管疾病存在的情况下，延长胎儿ICT可预测不良后果。(2)胎儿降主动脉脉波研究：利用超声追踪系统获取胎儿降主动脉脉波，明确胎龄相关变化及对心功能障碍的检测价值。采用脉冲波形计算收缩期峰值（PSD）和舒张末期直径（EDD）、脉冲幅值（Amp）和Amp:EDD比值进行分析。196例20周后正常胎儿PSD、EDD、Amp均随妊娠提前而升高，Amp:EDD比值呈线性下降。将19例疑似心功能不全的胎儿根据缩短分数和预负荷指数分为健康和心功能改变两组。其中7例心功能不全胎低Amp发生率（p<0.01）和Amp:EDD比值（p<0.001）显著高于其余12例心功能正常胎。胎儿降主动脉脉波分析对胎儿宫内心功能障碍的检测是有用的。

(1) Study on fetal isovolumetric contraction time: To study the fetal cardiac isovolumetric contraction time (ICT) in normal and complicated pregnancies with placental vascular disease, ICTs were measured in 160 normal fetuses and 55 complicated pregnancies. In normal pregnancy, the ICT remained constant with gestation and fetal heart rate. A strong correlation between prolonged ICT duration and abnormalities in the perinatal course, indicating that a prolonged fetal ICT predicts adverse outcome in the presence of placental vascular disease.(2) Study on fetal pulse waveform in the descending aorta: Pulse waveforms of the fetal descending aorta were obtained using an echo-tracking system to clarify the gestational age-related changes and the usefulness for detecting cardiac dysfunction. Peak-systolic (PSD) and end-diastolic diameter (EDD), pulse amplitude (Amp) and Amp:EDD ratio, calculated from the pulse waveforms, were adopted for analysis. In 196 normal fetuses after 20 weeks, the PSD, EDD and Amp increased, and Amp:EDD ratio decreased linearly with advancing gestation. The 19 fetuses with suspected cardiac dysfunction were divided into healthy and altered cardiac function subgroups, according to the values of fractional shortening and preload index. Of these, 7 fetuses with cardiac dysfunction had significantly higher incidence of low Amp (p<0.01) and Amp:EDD ratio (p<0.001) than remaining 12 fetuses with normal cardiac function. The pulse waveform analysis in the fetal descending aorta proved useful for detecting fetal cardiac dysfunction in utero.