早孕期胎儿心轴的参考值及其临床意义

目的探讨孕11^＋0~13^＋6周胎儿心轴的正常参考值范围，并评价早孕期测定胎儿心轴的临床应用价值。 方法选取2017年6月至2018年6月于南京医科大学附属苏州医院行早孕期超声检查的孕妇1639例，均为单胎妊娠，于早孕期超声检查时显示标准四腔心切面，于收缩期（房室瓣完全关闭时）测量心轴角度。 结果1631例正常胎儿心轴测量值范围为10.26°~74.02°，平均为（43.79±10.10）°。按照不同孕周将1631例胎儿分为11^＋0~11^＋6周、12^＋0~12^＋6周、13^＋0~13^＋6周3组，其胎儿心轴角度分别为（43.40±10.82）°、（43.91±9.88）°、（43.65±9.96）°，3组胎儿心轴比较差异无统计学意义（F=0.40375，P>0.05）。本研究采用普通人群中胎儿心轴角度的95%可信区间作为正常参考值范围，得出1631例早孕期胎儿心轴角度正常参考值范围为23.99~63.58°。1639例胎儿中，8例于早孕期诊断为先天性心脏病，其中6例心轴角度测量值异常（4例心轴向左侧偏移，1例心轴向右侧偏移，1例心轴无法测量）。 结论早孕期胎儿心轴角度测量及正常参考值范围的建立对于早孕期胎儿心脏超声筛查具有一定的价值，可作为早孕期诊断胎儿心脏畸形的指标之一。

Clinical value of fetal cardiac axis in the first trimester

ObjectiveTo explore the normal reference range for fetal cardiac axis in the first trimester, and to evaluate its clinical value. MethodsA total of 1639 unselected singleton pregnancies were enrolled from June 2017 to June 2018. Routine first trimester screening scan and fetal echocardiography were performed at 11^{+ 0}~13^{+ 6} weeks of gestation. The cardiac axis was assessed by obtaining an axial view of the fetal chest at the level of the four-chamber view (when the atrioventricular valve was completely closed). ResultsThe 1631 normal fetuses had a mean cardiac axis of (43.79±10.10)°, ranging from 10.80° to 74.02°. According to the gestational weeks, all pregnant women were divided into groups of 11^{+ 0}~11^{+ 6} weeks, 12^{+ 0}~12^{+ 6} weeks, and 13^{+ 0}~13^{+ 6} weeks, and the mean fetal cardiac axis for them were (43.40±10.82)°, (43.91±9.88)°, and (43.65±9.96)°, respectively; the difference among the three groups was not statistically significant (F=0.40375, P>0.05). The normal cardiac axis reference range was defined as 95% of the range of the fetal cardiac axis (23.99~63.58°). Among the 1639 fetuses, 8 were diagnosed with congenital heart disease in the first trimester, 6 of whom had abnormal cardiac axis value (4 cases of left axis deviation, 1 case of right axis deviation, and 1 case of unmeasurableness). ConclusionThe reference range of fetal cardiac axis in the first trimester may be helpful in improving the detection rate of congenital heart defects, and it can be used as one of the indicators for the diagnosis of congenital heart defects in the first trimester.