摘要目的:建立中晚孕期正常胎儿左心室流入道与流出道夹角(LIOA)参考范围，观察胎儿LIOA与孕周、心轴、心腔大血管内径、估测胎儿体重(EFW)的相关性。方法:前瞻性收集2022年11月至2023年4月于中南大学湘雅二医院行胎儿超声检查的中晚孕期(16～39 ＋6周)单胎胎儿651例。二维超声获取胎儿LIOA，建立中晚孕正常LIOA范围。采用Pearson相关分析法分析胎儿LIOA与孕周、心轴、心腔大血管内径、EFW的相关性。 结果:651例正常胎儿LIOA范围为(44.39±7.67)°。LIOA与心轴呈轻度正相关( r＝0.22， P<0.05)，LIOA与孕周、心腔大血管内径、EFW无明显相关性(均 P>0.05)。 结论:正常胎儿LIOA在妊娠中晚期是恒定的，其与心轴呈轻度正相关。建立胎儿LIOA正常参考值可为深入研究胎儿主动脉生物力学和血流动力学提供有效数据。

abstractsObjective:To establish the reference value of the angle between the left ventricular inflow and outflow tract (LIOA) in normal fetuses in the second and third trimesters, and observe the correlation between fetal LIOA and gestational age, cardiac axis, cardiac size, and estimated fetal weigh (EFW).Methods:Fetal LIOA in normal fetuses with gestational age from 16 weeks to 39 + 6 weeks were obtained prospectively by two-dimensional ultrasound in the Second Xiangya Hospital from November 2022 to April 2023. Pearson′s correlation coefficient was used to analyze the correlation between fetal LIOA and gestational age, cardiac axis, cardiovascural size and EFW. Results:The LIOA range of 651 normal fetuses was (44.39±7.67)°, and it was found that LIOA was not related to gestational age. LIOA mildly positively correlated with the cardiac axis ( r=0.22, P<0.05) while not correlated with gestational age, cardiovascural size or EFW (all P>0.05). Conclusions:The range of LIOA in normal fetuses were established. Fetal LIOA is constant in the second and third trimesters and it is mildly positively correlated with the cardiac axis. Evaluating fetal LIOA may also provide information for future research on the fetal aortic hemodynamic development.