Department of Anesthesiology and Critical Care Medicine, Hadassah Hebrew University Medical Center, Ein Karem, Jerusalem, Israel.
Department of Anesthesiology and Critical Care Medicine, Hadassah Hebrew University Medical Center, Ein Karem, Jerusalem, Israel; Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA; Wohl Institute of Translational Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel.
Placenta. 2020 Jan 15;90:52-57. doi: 10.1016/j.placenta.2019.11.006. Epub 2019 Nov 29.
We previously reported blood oxygen level dependent MRI (BOLD-MRI) for monitoring placental and fetal hemodynamic changes in mice following maternal hypercapnia. Here we use BOLD-MRI to compare the placental and fetal hemodynamic effects of different maternal vasopressors in mice.
Pregnant ICR mice (n = 16; E17.5) anesthetized with pentobarbital (80 mg/kg i.p.) were placed supine in a 4.7-T Bruker Biospec MRI. Following baseline images, equipotential doses of ephedrine (10 mg/kg) or phenylephrine (10mcg/kg) were administered intravenously. Changes in placental and fetal signal were analyzed from T2*-weighted gradient echo MR images (TR/TE = 147/10 ms). Different regions of interest (placenta, fetal heart, fetal liver and fetal brain) were identified. Percentage change of BOLD-MRI signal intensity (SI) were presented as time curves.
Ephedrine and phenylephrine elicited markedly different effects. Phenylephrine caused an approximate 50% reduction in placental, fetal heart and fetal liver BOLD-MRI-SI, but fetal brain BOLD-MRI-SI was unchanged (statistically different from placenta and other fetal organs; p < 0.001), and the fetal brain/liver BOLD-MRI-SI ratio was markedly increased versus baseline (p < 0.001). Following ephedrine, placental BOLD-MRI-SI increased 30% and fetal heart BOLD-MRI-SI was reduced 26%; other fetal organs were unchanged. Blood gases were unchanged.
Phenylephrine induced BOLD-MRI-SI changes suggestive of placental and fetal hypoperfusion with brain sparing. Ephedrine induced BOLD-MRI-SI changes suggestive of increased cardiac output; we speculate that reduced fetal heart BOLD-MRI-SI may be due to increased fetal myocardial oxygen extraction or metabolic acidosis. The result demonstrates the potential of BOLD-MRI as a non-invasive hemodynamic tool for assessing pharmacodynamics effects in the placental and fetus.
我们之前报道了血氧水平依赖磁共振成像（BOLD-MRI）在监测母体高碳酸血症后小鼠胎盘和胎儿血流动力学变化中的应用。在此，我们使用 BOLD-MRI 比较了不同血管加压药物对小鼠胎盘和胎儿血流动力学的影响。
将孕 ICR 小鼠（n=16；E17.5）麻醉后置于 4.7-T Bruker Biospec MRI 仪上仰卧位。静脉注射等剂量的麻黄碱（10mg/kg）或去氧肾上腺素（10mcg/kg）。使用 T2*-加权梯度回波 MR 图像（TR/TE=147/10ms）分析胎盘和胎儿信号的变化。确定不同的感兴趣区域（胎盘、胎儿心脏、胎儿肝脏和胎儿大脑）。BOLD-MRI 信号强度（SI）的百分比变化呈时间曲线。
麻黄碱和去氧肾上腺素引起的作用明显不同。去氧肾上腺素引起胎盘、胎儿心脏和胎儿肝脏 BOLD-MRI-SI 降低约 50%，但胎儿大脑 BOLD-MRI-SI 不变（与胎盘和其他胎儿器官有统计学差异；p<0.001），胎儿大脑/肝脏 BOLD-MRI-SI 比值明显升高（与基线相比；p<0.001）。麻黄碱后，胎盘 BOLD-MRI-SI 增加 30%，胎儿心脏 BOLD-MRI-SI 减少 26%；其他胎儿器官无变化。血气无变化。
去氧肾上腺素引起的 BOLD-MRI-SI 变化提示胎盘和胎儿低灌注伴有脑保护。麻黄碱引起的 BOLD-MRI-SI 变化提示心输出量增加；我们推测胎儿心脏 BOLD-MRI-SI 减少可能是由于胎儿心肌氧摄取增加或代谢性酸中毒。结果表明，BOLD-MRI 作为一种评估胎盘和胎儿药效动力学效应的非侵入性血流动力学工具具有潜力。
