Harris Birthright Research Centre for Fetal Medicine, Fetal Medicine Research Institute, King's College Hospital, London, UK.
School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
Ultrasound Obstet Gynecol. 2021 Feb;57(2):266-272. doi: 10.1002/uog.23522. Epub 2020 Dec 31.
Echocardiographic studies have reported that fetuses with low birth weight, compared to those with normal birth weight, have globular hearts and reduced cardiac function. Dichotomizing continuous variables, such as birth weight, may be helpful in describing pathology in small studies but can prevent us from identifying physiological responses in relation to change in size. The aim of this study was to explore associations between fetal cardiac morphology and function and birth weight, as a continuous variable, as well as uterine artery (UtA) pulsatility index (PI), as an indirect measure of placental perfusion, and the cerebroplacental ratio (CPR), as an indirect measure of fetal oxygenation.
This was a prospective study of 1498 women with singleton pregnancy undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Pregnancies complicated by pregestational or gestational diabetes mellitus, chronic hypertension, pregnancy-induced hypertension or pre-eclampsia were excluded from the analysis. Conventional and more advanced echocardiographic modalities, such as speckle tracking, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity indices. In addition, the PI of the UtA, umbilical artery (UA) and fetal middle cerebral artery (MCA) was determined and the CPR was calculated by dividing MCA-PI by UA-PI. Multiple linear regression models were used to assess determinants of fetal echocardiographic parameters.
The study population included 146 (9.7%) small-for-gestational-age (SGA) fetuses with birth weight < 10 percentile and 68 (4.5%) with fetal growth restriction (FGR). In the SGA and FGR groups, compared to the non-SGA and non-FGR fetuses, respectively, there was a more globular right ventricle and reduced left and right ventricular systolic function, and, from the left ventricular diastolic functional indices, the E/A ratio was increased. There was a linear association of right ventricular sphericity index, indices of left and right ventricular systolic function and E/A ratio with birth-weight Z-score. There were no significant associations between cardiac morphological and functional indices and UtA-PI Z-score or CPR Z-score.
This screening study at 35-37 weeks' gestation has demonstrated that birth weight is a determinant of fetal cardiac morphology and function but UtA-PI and CPR, as indirect measures of placental perfusion and fetal oxygenation, are not. This suggests that the differences in fetal cardiac indices between small and appropriately grown fetuses may be part of a normal physiological response to change in fetal size rather than part of a pathological adaptation to abnormal placental perfusion and fetal oxygenation. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.
超声心动图研究报告称，与正常出生体重的胎儿相比，低出生体重的胎儿心脏呈球形，心功能降低。将连续变量（如出生体重）二分为类可能有助于在小研究中描述病理学，但会阻止我们识别与大小变化相关的生理反应。本研究旨在探讨胎儿心脏形态和功能与出生体重（作为连续变量）、子宫动脉（UtA）搏动指数（PI）（作为胎盘灌注的间接测量指标）和脑-胎盘比（CPR）（作为胎儿氧合的间接测量指标）之间的关系。
这是一项前瞻性研究，纳入了 1498 名单胎妊娠女性，这些女性在妊娠 35+0 至 36+6 周时接受常规超声检查。排除了合并孕前或妊娠期糖尿病、慢性高血压、妊娠高血压或子痫前期的妊娠。使用常规和更先进的超声心动图方法（如斑点追踪）评估右心室和左心室的胎儿心功能。通过计算右心室和左心室的球形指数来评估胎儿心脏的形态。此外，还测定了 UtA、脐动脉（UA）和胎儿大脑中动脉（MCA）的 PI，并通过将 MCA-PI 除以 UA-PI 计算 CPR。采用多元线性回归模型评估胎儿超声心动图参数的决定因素。
研究人群包括 146 名（9.7%）出生体重小于第 10 百分位的小于胎龄儿（SGA）胎儿和 68 名（4.5%）胎儿生长受限（FGR）胎儿。与非 SGA 和非 FGR 胎儿相比，SGA 和 FGR 组的右心室更呈球形，左、右心室收缩功能降低，从左心室舒张功能指标来看，E/A 比值增加。右心室球形指数、左、右心室收缩功能指数和 E/A 比值与出生体重 Z 评分呈线性相关。心脏形态和功能指数与 UtA-PI Z 评分或 CPR Z 评分无显著相关性。
这项在 35-37 周时进行的筛查研究表明，出生体重是胎儿心脏形态和功能的决定因素，但 UtA-PI 和 CPR（作为胎盘灌注和胎儿氧合的间接测量指标）不是。这表明，小胎儿和适当生长胎儿之间的胎儿心脏指数差异可能是胎儿大小变化的正常生理反应的一部分，而不是对胎盘灌注和胎儿氧合异常的病理性适应的一部分。
