Study on fetal circulation using Doppler signal and pulse waveforms

(1)胎儿心脏等容收缩时间的研究：为探讨正常妊娠及合并胎盘血管疾病胎儿心脏等容收缩时间（ICT），对160例正常胎儿及55例合并胎盘血管疾病胎儿进行ICTs测定。在正常妊娠中，ICT与妊娠和胎心保持恒定。ICT持续时间延长和围产期异常之间存在强相关性，表明胎儿ICT持续时间延长可预测胎盘血管疾病的不良结局。(2)胎儿降主动脉脉搏波形的研究：使用回声跟踪系统获得胎儿降主动脉脉搏波形，以阐明与胎龄相关的变化以及检测心功能不全的有用性。采用收缩期峰值直径（PSD）、舒张末期直径（EDD）、脉搏幅度（PSV）及PSV/EDD比值进行分析。196例孕20周后正常胎儿的PSD、EDD、EVD均随孕龄的增加而增加，EVD/EDD比值随孕龄的增加而线性下降。根据短轴缩短率和前负荷指数将19例可疑心功能不全胎儿分为正常组和心功能异常组。其中7例心功能不全胎儿的低舒张压（p<0.01）和舒张压/舒张末期舒张压比值（p<0.001）显著高于其余12例心功能正常胎儿。胎儿降主动脉脉搏波形分析对胎儿宫内心功能异常的诊断有重要意义。

(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.