OP04.06: Evaluation of placental microvascular perfusion by SlowflowHD imaging in fetal congenital heart defects

Fetal cardiovascular system and placenta appear at the same time in embryology, so the morphology and function of placenta will change in the presence of congenital heart disease (CHD). The purpose of this study was to compare placental blood perfusion and function between normal fetus and CHD fetus. In this study, 40 fetuses were collected prospectively, including 20 cases of normal group and 20 cases of CHD group. CHD group included tetralogy of Fallot (n = 9), complete transposition of great arteries (n = 3), single ventricle (n = 2), congenital anomaly of aorta (n = 4) and total anomalous pulmonary venous drainage (n = 2). We engaged the SlowflowHD mode to visualise placental blood flow, and procured three-dimensional images. SlowflowHD can vividly display the placental basal plate, chorionic plate, primary villi, secondary villi, and tertiary villi and 3D reconstruction of the placental blood flow. Further, the spectral characteristics of all hierarchical levels of the villi can be extracted using spectral Doppler. Utilising virtual organ computer-assisted analysis (VOCAL) measurement software, the colour blood flow signal of the placental region of interest was numerically quantified as a histogram, and vascular index (VI), flow index (FI) and vascular flow index (VFI) were calculated automatically. The results showed that the umbilical vein blood flow, VI, FI and VFI in CHD group were lower than those in normal fetus. However, there was no significant difference in Doppler blood flow parameters of placental villi between the two groups. The distribution density of placental villi of CHD fetus is lower than that of normal fetus, and the blood flow index of placental parenchyma is lower than that of normal fetus. SlowflowHD imaging can be used as a scientific tool to study fetal heart-placental axis. This method helps to better understand the role of placenta in placental development, especially the placental differences in CHD.