OC080: Assessment of embryonic and placental blood flow & placental ultrastructure changed with contrast agent (SonoVueTM) in late pregnant rat

Abstract

The study was to investigate the ability of the contrast pulse sequencing technology (CPS) and SonoVueTM (a new contrast agent) to delineate placental angioarchitecture and their influence on placental function, circulation and ultrastructure. sixty late pregnant Wistar rats (median weight, 300 g; range, 260 g to 330 g; median gestational age, 19 days) were selected and divided into three experimental groups, i.e. control group (n=20) injected with 2.0 ml/kg physiologic saline solution, high dose group (n=20) injected with 10 mg/ml SonoVueTM 2.0 ml/kg (Bracco S.p.A., Milan, Italy), and low dose group (n=20) injected with 0.01 mg/ml SonoVueTM 2.0 ml/kg. One of placentas was randomly selected for examination by contrast enhanced ultrasonography. Maternal and embryonic heart rate (HR) and resistance index (RI), pulsatility index (PI), and systolic-diastolic ratio (S/D) in the embryonic middle cerebral artery (MCA), umbilical artery (UA), and uterine artery (UTA) were measured before and after administration of contrast agent or physiologic saline solution. In each group, fifteen rats were cesarean to take the placenta immediately after exam, other five did after 12 hours of exam. The ultrastructural changes of the placenta were observed by electron microscope. Intravascular injection of SonoVueTM was capable of delineating the vascular architecture of the villous tree of rat. No enhancement was seen after saline solution injections. There were no significant changes of resistance index (RI), pulsatility index (PI), and systolic-diastolic ratio (S/D) in the embryonic middle cerebral artery, umbilical artery, and uterine artery after administration of contrast agent or physiologic saline solution. The maternal and embryonic heart rate significantly decreased. However, differences among three groups were not statistically significant; In low dose group, there were no obvious changes of helicine artery in rats's placenta taken immediately and after 12 hours of examination. In high dose group, taken immediately, the helicine artery wall were uneven, there are blood platelet aggregate and accrete around the thinningz; draw it after 12 hours, the vessel wall were thickening and swell, to be missing normal architecture of the blood vessel wall, the endothelial cell exfoliate in Lumen of blood vessel, we can also see apoptotic body in it. Contrast-enhanced ultrasonography limpidly presents the characteristics of perfusion of placenta in a rat model and does not affect the embryonic hemodynamic parameters. Low dose contrast agent does not impact ultrastructural changes of placent. High dose contrast agent can influence on ultrastructural of helicine artery wall.