Gordon Zoya, Eytan Osnat, Jaffa Ariel J, Elad David
Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv Univ., Tel Aviv 69978, Israel.
Am J Physiol Regul Integr Comp Physiol. 2007 Feb;292(2):R977-82. doi: 10.1152/ajpregu.00410.2006. Epub 2006 Oct 12.
The Hyrtl anastomosis is a common connection between the umbilical arteries near the cord insertion in most human placentas. It has been speculated that it equalizes the blood pressure between the territories supplied by the umbilical arteries. However, its functional role in the regulation and distribution of fetal blood flow to the placenta has not yet been explored. A computational model has been developed for quantitative analysis of hemodynamic characteristic of the Hyrtl anastomosis in cases of discordant blood flow in the umbilical arteries. Simulations were performed for cases of either increased placental resistance at the downstream end or reduced arterial blood flow due to some pathologies upstream of one of the arteries. The results indicate that when placental territories of one artery impose increased resistance to fetal blood flow, the Hyrtl anastomosis redistributes the blood flow into the second artery to reduce the large pressure gradients that are developed in the affected artery. When one of the arteries conducts a smaller blood flow into the placenta and a relatively smaller pressure gradient is developed, the Hyrtl anastomosis rebuilds the pressure gradients in the affected artery and redistributes blood flow from the unaffected artery to the affected one to improve placental perfusion. In conclusion, the Hyrtl anastomosis plays the role of either a safety valve or a pressure stabilizer between the umbilical arteries at the placental insertion.
希尔特尔吻合是大多数人类胎盘脐带插入处附近脐动脉之间的常见连接。据推测，它可使脐动脉供血区域之间的血压均衡。然而，其在调节和分配胎儿流向胎盘的血流中的功能作用尚未得到探索。已开发出一种计算模型，用于定量分析脐动脉血流不一致情况下希尔特尔吻合的血流动力学特征。针对下游端胎盘阻力增加或某一动脉上游因某些病变导致动脉血流减少的情况进行了模拟。结果表明，当一条动脉的胎盘区域对胎儿血流施加增加的阻力时，希尔特尔吻合将血流重新分配到第二条动脉，以减小受影响动脉中形成的大压力梯度。当其中一条动脉向胎盘输送的血流较少且形成相对较小的压力梯度时，希尔特尔吻合会重建受影响动脉中的压力梯度，并将血流从未受影响的动脉重新分配到受影响的动脉，以改善胎盘灌注。总之，希尔特尔吻合在胎盘插入处的脐动脉之间起到安全阀或压力稳定器的作用。
