Tchirikov Michael
University Clinic of Obstetrics and Gynecology, Johannes Gutenberg University of Mainz, Mainz, Germany.
Am J Obstet Gynecol. 2008 Jan;198(1):138.e1-6. doi: 10.1016/j.ajog.2007.06.066.
The reduction of resistance to flow in the ductus venous (DV) and a decrease of blood supply to the liver serve for the survival of the fetus during hypoxia. The present study investigated the influence of the increased diameter of the DV on placental blood perfusion.
In 15 ewes with twin pregnancies at gestational ages of 117 +/- 4 days, a stent (4 or 5 mm) was placed into the DV of 1 twin (DV(stent) group) under ultrasound guidance. Blood flow rates in the umbilical vein (UV) and DV of both fetuses were measured using Doppler ultrasound. Eight pairs of twin fetuses were included for the final analysis.
The dilatation of the DV increased the blood flow volume rate passed through the DV from 136.61 +/- 41.07 to 398.93 +/- 86.62 (mL/min(-1), P < .0001) and also significantly increased placental blood perfusion from 454.35 +/- 143.0 in control twin to 663.56 +/- 167.36 in the DV(stent) group (P < .05, mL/min(-1)), respectively. The DV/UV ratio increased from 30.6 +/- 11.6% in the control group to 58.9 +/- 11.6% in DV(stent) gemini (P < .0001). The positive effect of DV dilation on the placental blood perfusion was stable and could be observed up to 3 weeks after the operation.
The dilatation of the DV by means of stent implantation in the DV increased the blood flow volume rate in the umbilical vein. Fetal surviving mechanism, the increase of DV shunting rate including redistribution of the blood flow in the liver with a reduction of DV resistance to flow, could have a second effect: the improvement of reduced placental blood perfusion during hypoxia.
降低静脉导管（DV）的血流阻力并减少肝脏血液供应有助于胎儿在缺氧时存活。本研究调查了DV直径增加对胎盘血液灌注的影响。
在15只妊娠117±4天的双胎妊娠母羊中，在超声引导下将一个支架（4或5毫米）放置到其中一个双胎胎儿的DV中（DV（支架）组）。使用多普勒超声测量两个胎儿的脐静脉（UV）和DV中的血流速度。最终分析纳入了8对双胎胎儿。
DV扩张使通过DV的血流量率从136.61±41.07增加到398.93±86.62（mL/min⁻¹，P<.0001），并且也使胎盘血液灌注从对照组双胎胎儿的454.35±143.0显著增加到DV（支架）组的663.56±167.36（P<.05，mL/min⁻¹）。DV/UV比值从对照组的30.6±11.6%增加到DV（支架）双胎胎儿的58.9±11.6%（P<.0001）。DV扩张对胎盘血液灌注的积极作用是稳定的，并且在手术后长达3周都可以观察到。
通过在DV中植入支架使DV扩张增加了脐静脉中的血流量率。胎儿存活机制，即DV分流率增加，包括肝脏血流重新分布以及DV血流阻力降低，可能还有第二个作用：改善缺氧时胎盘血液灌注减少的情况。
