Bonnin P, Fouron J C, Teyssier G, Sonesson S E, Skoll A
Department of Pediatrics, Saint-Justine Hospital, University of Montreal, Canada.
Circulation. 1993 Jul;88(1):216-22. doi: 10.1161/01.cir.88.1.216.
This study investigated the effects of impairment to placental flow on flow patterns through the aortic isthmus because in the fetus, this vascular segment is the link between the parallel vascular systems perfused by the left and right ventricles.
A progressive increase in resistance to blood flow through the placenta was created in seven exteriorized fetal lambs by mechanical umbilical vein compression. Blood flows were measured in the ascending aorta, pulmonary artery, aortic isthmus, and umbilical artery at baseline and at each compression level. The severity of the levels of compression was determined by changes in the flow profile through the umbilical artery. An increase in placental resistance causing a fall in umbilical blood flow of approximately 50% was associated with a retrograde diastolic flow through the aortic isthmus even though the diastolic flow through the umbilical artery remained forward. Because of the systolic predominance, however, the net flow in the isthmus was forward. With a more severe increase in placental resistance corresponding to a decrease of 75% in umbilical blood flow, the net flow through the isthmus approached zero. A strong positive correlation was found between the umbilical blood flow and the net flow through the aortic isthmus (r = .89).
Variations in Doppler blood flow velocity waveforms and integrals of the aortic isthmus can be used as a sensitive indicator of the state of the umbilical circulation.
本研究调查了胎盘血流受损对通过主动脉峡部血流模式的影响，因为在胎儿中，该血管段是由左右心室灌注的平行血管系统之间的连接。
通过机械性压迫脐静脉，在7只体外胎儿羔羊中逐渐增加胎盘血流阻力。在基线时以及每个压迫水平下，测量升主动脉、肺动脉、主动脉峡部和脐动脉中的血流。压迫水平的严重程度通过脐动脉血流曲线的变化来确定。胎盘阻力增加导致脐血流量下降约50%，即使脐动脉舒张期血流仍为正向，但与主动脉峡部舒张期逆向血流相关。然而，由于收缩期占优势，峡部的净血流为正向。随着胎盘阻力更严重增加，对应脐血流量减少75%，通过峡部的净血流接近零。发现脐血流量与通过主动脉峡部的净血流之间存在强正相关（r = 0.89）。
主动脉峡部多普勒血流速度波形和积分的变化可作为脐循环状态的敏感指标。
