Hemodynamic factors associated with fetal cardiac remodeling in late fetal growth restriction: a prospective study

Altered cardiac geometry affects a proportion of fetuses with growth restriction (FGR). The aim of this study was to explore the hemodynamic factors associated with cardiac remodeling in late FGR. This was a prospective study of singleton pregnancies complicated by late-onset FGR undergoing assessment of left (LV) and right (RV) ventricular sphericity-index (SI). The study population was divided in two groups according to the presence of cardiac remodelling, defined as LVSI <5th centile. The following outcomes were explored: Gestational age at birth, birthweight, caesarean section (CS) for fetal distress, umbilical artery (UA) pH and neonatal admission to special care unit. The differences between the 2 groups in UA pulsatility index (PI), middle cerebral artery (MCA) PI, uterine artery PI, cerebroplacental ratio (CPR) and umbilical vein (UV) flow corrected for fetal abdominal circumference (UVBF/AC) were tested. In total, 212 pregnancies with late FGR were enrolled in the study. An abnormal LV SI was detected in 119 fetuses (56.1%). Late FGR fetuses with cardiac remodeling had a lower birthweight (2390 g vs. 2490; P = 0.04) and umbilical artery pH (7.21 vs. 7.24; P = 0.04) and were more likely to have emergency CS (42.8% vs. 26.9%; P = 0.023) and admission to special care unit (13.4% vs. 4.3%; P = 0.03) compared to those with normal LVSI. No difference in either UA PI (p = 0.904), MCA PI (P = 0.575), CPR (P = 0.607) and mean uterine artery PI (P = 0.756) were present between fetuses with or without an abnormal LV SI. Conversely, UVBF/AC z-score was lower (-1.84 vs.-0.99; P ≤ 0.001) in fetuses with cardiac remodeling and correlated with LV (P ≤ 0.01) and RV SI (P ≤ 0.02). Fetal cardiac remodelling occurs in a significant proportion of pregnancies complicated by late FGR and is affected by a high burden of short-term perinatal compromise. The occurrence of LV SI is independent from fetal arterial Dopplers while it is positively associated with umbilical vein blood flow.