Tchirikov M, Strohner M, Popovic S, Hecher K, Schröder H J
Department of Obstetrics and Fetal Medicine, Johannes Gutenberg Universität Mainz, University Medical Center Mainz, Mainz, Germany.
Ultrasound Obstet Gynecol. 2008 Dec;32(7):917-22. doi: 10.1002/uog.5364.
To measure changes in cardiac output (CO) after partial cord occlusion in fetal sheep in order to investigate pathophysiological fetal adaptation mechanisms in a simulated acute placental insufficiency model under standardized conditions, with the aim of finding relevant methods for monitoring human fetuses during stress situations.
We used minimally invasive, percutaneous endoscopic techniques to close umbilical vessels in mid-gestational fetal sheep. Placental blood flow was reduced by preferentially closing first arterial and then the concomitant venous umbilical vessels within a short time interval. The investigations were carried out on 11 pregnant ewes at a median gestational age of 86 (range, 73-95) days. Major placental arteries and veins were occluded permanently by coagulation with bipolar forceps under percutaneous fetoscopic control. The fetal CO and Doppler parameters in the ductus venosus (DV), umbilical artery (UA) and umbilical vein (UV) were measured.
In spite of heart rate reduction, the CO was not significantly affected by vessel occlusion (mean +/- SD, 500 +/- 194 mL/min before and 457 +/- 219 mL/min after coagulation) because stroke volume slightly increased from 2.65 +/- 1.16 mL/beat to 3.1 +/- 1.5 mL/beat. The right to left CO ratio remained at 1.4. The UV flow/combined CO ratio decreased from 34 +/- 14% to 25 +/- 10% after vessel coagulation. The pulsatility index in the DV increased from 0.4 +/- 0.1 to 0.7 +/- 0.4. The DV blood flow volume remained relatively constant after the intervention. The DV shunting rate, given as DV/UV flow ratio, increased significantly from 30.8 +/- 4.7% to 59.3 +/- 25.0%.
The nearly simultaneous closure of arterial and venous umbilical vessels changed the flow pattern in the UA and significantly reduced placental blood perfusion. It did not distinctly change the blood flow volume rate through the DV, and consequently the DV shunting rate was increased. The combined CO was not significantly affected by the vascular obstruction, whereas the fraction of combined CO directed to the placenta was reduced.
测量胎羊部分脐带闭塞后心输出量（CO）的变化，以便在标准化条件下，于模拟急性胎盘功能不全模型中研究胎儿病理生理适应机制，旨在找到在应激情况下监测人类胎儿的相关方法。
我们采用微创经皮内镜技术闭合妊娠中期胎羊的脐血管。通过在短时间间隔内优先闭合动脉然后伴随的静脉脐血管来减少胎盘血流。对11只妊娠母羊进行了研究，妊娠中期的中位数为86（范围73 - 95）天。在经皮胎儿镜控制下，用双极钳凝固永久性闭塞主要胎盘动脉和静脉。测量胎儿的CO以及静脉导管（DV）、脐动脉（UA）和脐静脉（UV）中的多普勒参数。
尽管心率降低，但CO并未受到血管闭塞的显著影响（平均值±标准差，凝固前为500±194 mL/分钟，凝固后为457±219 mL/分钟），因为每搏输出量从2.65±1.16 mL/次搏动略有增加至3.1±1.5 mL/次搏动。左右心输出量比值保持在1.4。血管凝固后，UV血流/总心输出量比值从34±14%降至25±10%。DV的搏动指数从0.4±0.1增加至0.7±0.4。干预后DV血流量保持相对恒定。以DV/UV血流比值表示的DV分流率从30.8±4.7%显著增加至59.3±25.0%。
动脉和静脉脐血管几乎同时闭合改变了UA中的血流模式，并显著降低了胎盘血液灌注。它并未明显改变通过DV的血流量率，因此DV分流率增加。总心输出量未受到血管阻塞的显著影响，而流向胎盘的总心输出量比例降低。
