The vital role the ductus arteriosus plays in the fetal diagnosis of congenital heart disease: Evaluation by fetal echocardiography in combination with an innovative cardiovascular cast technology

BackgroundThe ductus arteriosus (DA) is one of the most important vessels of the fetal circulation. A variety of fetal congenital heart disease (CHD) may greatly influence the structure and flow patterns of the DA. This study was to investigate the structural characteristics of the DA and its value in the diagnosis of fetal CHD using fetal echocardiography combined with cardiovascular casting technology.MethodsTwenty-six cases of a normal fetus and 20 cases of a fetus with CHD (10 cases of right-sided obstructive CHD and 10 cases of left-sided obstructive CHD) were enrolled in this study. The three-vessel view and the long axis view of the DA arch were chosen to observe the fetal DA. The diameters of the ascending aorta (AO) and the pulmonary artery trunk (PA) were measured on the left ventricular outflow tract view and the three-vessel view separately, and AO/DA and PA/DA values were calculated separately. The flow direction of the DA was recorded, and the blood flow peak velocity was measured using color and spectral Doppler technology. Cardiovascular cast specimens were made for fetuses secured from induced labor to facilitate further observations of the true form and connections of the DA. At the same time, heart and great vessel deformities were also recorded through careful observation of the cardiovascular cast.ResultsThe following DA anomalies were observed: ① abnormal diameter (6 cases of stenosis and 9 cases of dilatation); ② abnormal blood flow direction (reverse flow in 5 cases); ③ abnormal blood flow speed (12 cases); ④ abnormal connection site (right-sided DA in 2 cases and a DA connection between the left pulmonary artery and the left subclavian artery in one case); and ⑤ absence of the DA in 2 cases. Compared with the control group, the DA diameter in the right-sided obstructive group was obviously narrowed; by contrast, the diameter of the DA in the left-sided obstructive group was obviously dilated. These differences were statistically significant (p < 0.05). Compared with the control group, the AO/DA values in the right- and left-sided obstructive groups were significantly increased and decreased, respectively. Finally, relative to the control group, the PA/DA values of the right- and left-sided obstructive groups were significantly reduced.ConclusionsDA enlargement was often associated with left-sided obstructive CHD, whereas a small DA and reverse blood flow often indicated the presence of right-sided obstructive CHD. DA connections can manifest with multiple anatomical variations. During fetal echocardiography, evaluation of the DA is very important; such analyses may help search for associated cardiac defects whenever a diagnosis of CHD is made.