Four novel types of placental villous trees: Insights from Slow flow HD ultrasound imaging into placental microvascular architecture in congenital heart disease

OBJECTIVE: Placental vascular development is critical for maternal-fetal exchange, and altered fetal cardiovascular physiology in congenital heart disease (CHD) may impact placental circulation. This study aimed to assess whether SlowflowHD imaging technology could qualitatively evaluate alterations in placental vascular structure in CHD. METHODS: A cross-sectional study was conducted using SlowflowHD to image placental vasculature in 215 fetuses, normal (n = 106) and CHD (n = 109) including critical CHD (CCHD) (n = 66) and other fetal heart disease (FHD) (n = 43). SlowflowHD provided two-dimensional (2D) and three-dimensional (3D) imaging of placental villous tree structures. Differences in display rates and distribution characteristics of placental villous trees were analyzed between the normal, CCHD, and FHD groups. RESULTS: SlowflowHD imaging technology demonstrated high sensitivity in visualizing placental vascular structures, with overall display rates of 95.5%-100%. Primary, secondary, and tertiary villi were visualized with rates of 95.5%-100%, 69.7%-97.7%, and 34.8%-88.7%, respectively. Four distinct placental villous tree types (types 0-3) were identified, exhibiting different distribution characteristics. The composition ratios of these types differed significantly between normal and CCHD fetuses, as well as between CCHD and FHD groups (P < 0.05). CONCLUSION: SlowflowHD imaging technology effectively identifies and characterizes placental villous tree structures. Placental villous trees in CCHD fetuses display sparser distribution patterns compared with normal fetuses, highlighting potential implications for maternal-fetal exchange in CHD.