Correlations between fetal left ventricular Tei index and different hemodynamic parameters during middle and late pregnancy at high altitudes
Jiao Ni, Hongjian Chen, Nianqiao ChenAbstract
Objectives
To compare fetal left ventricular Tei index (TI) values and hemodynamic correlations between high-altitude and low-altitude pregnancies, establishing an altitude-specific framework for fetal cardiac assessment.
Methods
This prospective dual-group study enrolled 234 high-altitude and 252 low-altitude singleton pregnancies in Yunnan, China. Standardized Doppler ultrasound was performed at 20–25, 30–34, and 37–40 weeks. Fetal TI and hemodynamic parameters (umbilical artery [UA], ductus venosus [DV], middle cerebral artery [MCA], uterine artery [UtA]) were measured using a Samsung WS80A ultrasound system with strict angle control (<20° for vessels, <15° for TI).
Results
TI elevation: High-altitude TI was consistently higher (all p<0.001): 20–25 w: 0.471 ± 0.027 versus 0.405 ± 0.131 (Δ16.3 %); 30–34 w: 0.492 ± 0.050 versus 0.384 ± 0.121 (Δ28.1 %); 37–40 w: 0.484 ± 0.052 versus 0.365 ± 0.148 (Δ32.6 %). Gestational divergence: TI decreased with gestation in high-altitude group (F=4.037, p=0.019) but remained stable in low-altitude group (F=1.421, p=0.244). TI was negatively correlated with Dominant TI-MCA-PSV (r=−0.383) and TI-DV-PAV (r=−0.314) at high altitude, while showing a positive correlation with Strongest TI-UA-S/D (r=0.257) at low altitude.
Conclusions
Chronic hypoxia induces a distinct fetal cardiovascular phenotype characterized by Tei index elevation (>0.48 post-30w), venous compromise (DV-PAV), and cerebral compensation (MCA-PSV). The tri-parametric model (TI + DV-PAV + MCA-PSV) addresses critical gaps in altitude-agnostic guidelines, offering tailored surveillance for 140 million high-altitude pregnancies globally.