OC5.05: Changes in fetal cardiac geometry with gestation: implications for three‐dimensional fetal echocardiography

Three-dimensional (3D) fetal echocardiography can be performed using algorithms designed to systematically examine fetal cardiac anatomy. Algorithms proposed thus far assume that the spatial relationships among cardiac chambers and great vessels are constant throughout gestation. However, if this assumption is not correct, the approach to 3D fetal echocardiography will have to be modified. The objective of this study was to examine whether changes in fetal cardiac geometry occur during gestation. A cross-sectional study was conducted of fetuses examined between 12 and 41 weeks. All patients had uncomplicated pregnancies and singleton gestations. Fetal heart volumes were acquired using 3D/4D ultrasonography with Spatio Temporal Image Correlation and examined using 4D View Software. The multiplanar display was used to analyze one frame of the cardiac cycle during systole. Parameters measured included the angles between 1) the ductal arch and fetal thoracic aorta; 2) the ductal arch and aortic arch; and 3) the left outflow tract and main pulmonary artery as seen in the short axis of the heart. The mean angle from the left outflow tract to the short axis was calculated. Non-parametric statistics were used for analysis. Sixty-four fetuses were included in the study. The angle between ductal arch and the fetal thoracic aorta decreased with gestational age (Spearman's rho coefficient: − 0.37; p < 0.001). In contrast, the angle between the ductal arch and aortic arch, and the mean angle between the left outflow tract and the short axis of the heart increased with gestational age (Spearman's rho coefficients: 0.45 and 0.47 respectively; p < 0.001) (see Table below). 1) Changes in fetal cardiac geometry were demonstrated with advancing gestational age; 2) Proposed algorithms for the examination of the fetal heart with 3D ultrasound need to be modified to optimize visualization of the standard planes before 20 weeks of gestation.