A study on normal fetal heart size Z-score model derived from fetal echocardiography

Abstract

Objective To construct Z-score models for normal fetal heart size measurements derived from fetal echocardiography. Methods Fetal echocardiography were performed in 910 normal singleton fetuses from 14th to 40th gestational weeks. Fetal transverse heart diameter (HD), heart length (HL), heart circumference (HC) and heart area (HA) were derived from a standard four-chamber view during end diastole. Using fetal somatic sizes as independent variables and heart sizes as dependent variables, the regression analyses of the mean (M) and the standard deviation (SD) for each parameter were calculated separately. A group of fetal heart diseases were assessed using these models. Results Strong correlations were found between fetal heart sizes and somatic sizes. Linear-cubic regression equations were each fitted to the models of the means of the heart sizes, whereas linear-quadratic equations were fitted to the models of the SDs. HD (r=0.984-0.986) was a dependent variable that provided the highest correlation coefficient with all of the fetal sizes, followed by HL (r=0.981-0.984), HC (r=0.981-0.982) and HA (r=0.978-0.979). All fetuses with Ebstein's anomaly and most with homozygous α-thalassemia-1 demonstrated Z-scores reflective of increased heart sizes. Conclusions The fetal heart sizes Z-scores models had been constructed. The calculation of Z-scores for heart sizes as a function of fetal somatic size is feasible and simple. They might be useful for quantitative assessment of some cardiac diseases and used as new predictive indicators for homozygous α-thalassemia-1 particularly. Key words: Ultrasonography, prenatal; Heart size; Z-score