产前超声评价正常孕中晚期胎儿主动脉峡部血流动力学变化

目的 应用产前超声分析胎儿主动脉峡部血流动力学的变化规律及收缩末期切迹与胎儿大脑血管发育的关系。方法 收集发育正常的151胎孕23~36⁺⁶周胎儿，采用CDFI和脉冲多普勒技术采集胎儿主动脉峡部及大脑中动脉血流频谱，测量大脑中动脉收缩期峰值血流速度（MCA-S）、主动脉峡部收缩期峰值血流速度（PSV）和收缩末期最低点血流速度（NS），计算收缩指数（ISI），并分析PSV、NS、ISI、MCA-S与孕周及NS与MCA-S的相关关系。结果 孕23周胎儿主动脉峡部频谱可见收缩末期浅切迹，随孕周增加逐渐加深，至孕30周左右时到达基线，之后出现反向。随着孕周增加，胎儿主动脉峡部PSV和MCA-S逐渐增大，而NS及ISI逐渐减小；随着MCA-S增加，NS呈现降低趋势。以孕周为自变量X，分别以主动脉峡部PSV、NS、ISI和MCA-S为因变量Y行曲线拟合，获得曲线方程分别为NS：Y=-110.982+10.975X-0.242X²（R²=0.971，P<0.001）；PSV：Y=-20.077+5.840X-0.073X²（R²=0.794，P<0.001）；ISI：Y=-0.705+0.087X-0.002X²（R²=0.970，P<0.001）；MCA-S：Y=-67.291+4.841X-0.036X²（R²=0.911，P<0.001）。以MCA-S为自变量X，NS为因变量Y进行拟合，获得曲线方程为Y=12.757+0.580X-0.020X²（R²=0.854，P<0.001）。结论 随孕周增加，胎儿MCA-S和主动脉峡部PSV增大，NS和ISI均减小。NS与MCA-S呈负相关，推测胎儿主动脉峡部收缩末期减速切迹的变化与大脑血管网的发育有关。

Prenatal ultrasonic evaluation on hemodynamics of aortic isthmus in normal fetus during middle and late pregnancy

Objective To analyze the changes of hemodynamics in fetal aortic isthmus (AOI) and the relationship between end-systolic notch and the development of fetal cerebral vascular using prenatal ultrasound. Methods A total of 151 normal fetuses at 23-36⁺⁶ gestation weeks were enrolled. Blood flow spectrum of fetal aortic isthmus and middle cerebral artery were collected with CDFI and pulsed Doppler technique. The peak systolic velocity (PSV) and the systolic nadir (NS) of AOI and peak systolic velocity of middle cerebral artery (MCA-S) were measured, and the isthmic systolic index (ISI) was calculated. Their relationship of gestational weeks and PSV, NS, ISI and MCA-S as well as the relationship between NS and MCA-S were analyzed. Results The shallow systolic end notch of AOI occurred at 23^rd week and deepened gradually as gestational age increased, reaching the baseline at about 30th week, and then reversed. With the gestational weeks increasing, PSV and MCA-S increased, while NS and ISI decreased gradually. With MCA-S increasing, NS showed a decreased trend. The curve equations were established regarding the gestation age as the independent variable X,PSV, NS, ISI and MCA-S as the dependent variable Y, respectively. NS:Y=-110.982+10.975X-0.242X² (R²=0.971, P<0.001); PSV:Y=-20.077+5.840X-0.073X² (R²=0.794, P<0.001); ISI:Y=-0.705+0.087X-0.002X² (R²=0.970, P<0.001); MCA-S:Y=-67.291+4.841X-0.036X² (R²=0.911, P<0.001). A curve equation was established regarding MCA-S as the independent variable X, NS as the dependent variable Y, Y=12.757+0.580X-0.020X² (R²=0.854, P<0.001). Conclusion With gestational age increasing, PSV of fetal AOI and MCA-S increased, while NS and ISI decreased. NS was negatively correlated with MCA-S, indicating that the change of the systolic end notch of fetal AOI is related to the development of fetal cerebral vascular network.