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We report 3 cases of prenatal diagnosis of premature constriction of the ductus arteriosus after maternal benzydamine hydrochloride therapy (3-mg lozenges) in third-trimester pregnancies. In each case, fetal echocardiography revealed a dilated, hypocontractile right ventricle with severe tricuspid regurgitation and constriction of the ductus arteriosus. Although the effect of indomethacin and other nonsteroidal anti-inflammatory drugs on prenatal ductal constriction is well known, readily available over-the-counter nonsteroidal anti-inflammatory drugs such as benzydamine can have an equally deleterious effect and are best avoided in the third trimester of pregnancy., (© 2015 by the American Institute of Ultrasound in Medicine.)

Premature constriction or closure of the ductus arteriosus can occur during fetal life. It is a rare phenomenon and has been described secondary to medication or structural lesions or as idiopathic constriction. Premature closure of the ductus arteriosus can lead to progressive right heart dysfunction with tricuspid regurgitation, congestive heart failure, fetal hydrops, and intrauterine death. This series describes diagnosis of fetal ductus arteriosus constriction of unknown etiology in 3 cases, prenatal management, and outcomes. Constriction of the ductus arteriosus can be diagnosed prenatally with careful interrogation of the ductal arch using pulsed Doppler sonography and complete fetal echocardiography. Close monitoring is mandatory to rule out development of right heart failure and to determine the intervention time.

Objective: Three- and 4-dimensional fetal echocardiography can be performed using novel algorithms. However, these algorithms assume that the spatial relationships among cardiac chambers and great vessels are constant throughout gestation. The objective of this study was to determine whether changes in fetal cardiac geometry occur during gestation., Methods: A cross-sectional study was conducted by reviewing 3- and 4-dimensional volume data sets from healthy fetuses obtained between 12 and 41 weeks of gestation. Volume data sets were examined using commercially available software. Parameters measured included 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. Nonparametric statistics were used for analysis., Results: Eighty-five fetuses were included in the study. The angle between the ductal arch and the fetal thoracic aorta decreased with gestational age (Spearman rho coefficient: -0.39; P < .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 rho coefficients: 0.45 and 0.40, respectively; P < .001)., Conclusions: (1) Changes in fetal cardiac geometry were shown with advancing gestational age. (2) Proposed algorithms for the examination of the fetal heart with 3-dimensional ultrasonography may need to be adapted to optimize visualization of the standard planes before 26 weeks of gestation.

The Coanda effect (the tendency of a jet stream to adhere to a boundary wall), and the relevant anatomy, may explain the location of ductal jets within the main pulmonary artery. With the usual insertion of the duct close to the left pulmonary artery, during right ventricular ejection, the ductal jet adheres to the left wall of the main pulmonary artery. When right ventricular ejection is absent in pulmonary atresia, the ductal jet streams down the right wall of the pulmonary artery to the pulmonary valve, reverses, and maintains a parallel column back toward the bifurcation. If the reversed flow is mistaken for ejection from the right ventricle, the diagnosis of pulmonary atresia may be missed.

The feasibility of fetal echocardiographic examination using three-dimensional ultrasonography was investigated in 54 healthy pregnant women with uncomplicated pregnancies between 17 and 37 weeks of gestation. In 46 cases (85.2%), good quality three-dimensional volumes of the fetal heart were obtained from both apical and lateral four-chamber views. By reslicing apical volumes, the reformatted sections of the long axis view of the left ventricle and the aortic crest were seen in 40 (87%) and 38 (83%) of 46 cases, respectively. The short axis was seen in 26 (57%) and ductal arch in 30 (65%) cases. The examination of lateral volumes was much less successful. The short axis was seen in 11 (24%) cases, and the aortic crest in 22 (48%), whereas the analysis of the longitudinal views was not possible. The best results were obtained at a gestational age between 22 and 27 weeks. Three-dimensional fetal echocardiography allowed the examination of the four chambers of the heart and left outflow tract during the late second trimester. The technique may become useful for the screening and diagnosis of congenital cardiac defects in the future.