Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
Mount Sinai Hospital, Toronto, Ontario, Canada.
Biol Reprod. 2019 Oct 25;101(4):823-831. doi: 10.1093/biolre/ioz128.
Antenatal corticosteroids are often administered to women at risk of preterm birth to accelerate fetal lung development; however, there is evidence that this treatment may adversely affect placental function in some fetuses. Our group has recently demonstrated that wave reflections in the umbilical artery (UA), measured using high-frequency ultrasound, are sensitive to placental vascular abnormalities. In the present study, we used this approach to investigate the effect of maternal administration of betamethasone, a clinically relevant corticosteroid, on the feto-placental vasculature of the mouse. Fetuses were assessed at embryonic day (E)15.5 and E17.5 in C57BL6/J mice. At both gestational ages, the UA diameter, UA blood flow, and the wave reflection coefficient were significantly elevated in the betamethasone-treated mice compared to vehicle-treated controls. These observations support the interpretation that placental vascular resistance dropped with betamethasone treatment to an extent that could not be explained by vasodilation of the UA alone. Consistent with clinical studies, the effect of betamethasone on UA end-diastolic velocity was heterogeneous. Our results suggest that UA wave reflections are more sensitive to acute changes in placental vascular resistance compared with the UA pulsatility index, and this technique may have clinical application to identify a favorable placental vascular response to fetal therapies such as antenatal corticosteroids, where the fetal heart rate is likely to vary.
产前皮质类固醇经常被用于有早产风险的孕妇，以加速胎儿肺部发育；然而，有证据表明，这种治疗方法可能会对某些胎儿的胎盘功能产生不利影响。我们的研究小组最近证明，使用高频超声测量的脐动脉（UA）反射波对胎盘血管异常敏感。在本研究中，我们使用这种方法来研究母体给予倍他米松（一种临床相关的皮质类固醇）对小鼠胎-胎盘血管的影响。在 C57BL6/J 小鼠中，于胚胎期 15.5 天（E15.5）和 17.5 天（E17.5）评估胎儿。在这两个胎龄，与对照组相比，倍他米松处理组的 UA 直径、UA 血流量和反射波系数显著升高。这些观察结果支持以下解释：与单独的 UA 扩张相比，胎盘血管阻力随着倍他米松治疗而下降，下降程度无法用 UA 来解释。与临床研究一致，倍他米松对 UA 舒张末期速度的影响是异质的。我们的结果表明，与 UA 搏动指数相比，UA 反射波对胎盘血管阻力的急性变化更敏感，这种技术可能具有临床应用价值，可用于识别胎儿治疗（如产前皮质类固醇）对胎盘血管的有利反应，因为胎儿心率可能会发生变化。
