First-Trimester Echocardiographic Features and Perinatal Outcomes in Fetuses With Congenital Absence of the Aortic Valve.

Objectives: The purpose of this study was to describe the echocardiographic features and perinatal outcomes of congenital absence of the aortic valve diagnosed by first-trimester echocardiography.

Methods: This retrospective study assessed the feasibility of first-trimester echocardiography in detecting absence of the aortic valve. All cases of absence of the aortic valve diagnosed by first-trimester fetal echocardiography from January 2010 to December 2014 were identified at a single referral center using an established perinatal database. Demographic information, echocardiograms, perinatal outcomes, and autopsy reports were reviewed. Echocardiographic features were described.

Results: A total of 50,822 fetuses underwent first-trimester echocardiography during the study period. Ten cases of congenital absence of the aortic valve were diagnosed, for an overall incidence rate of 0.019%. The earliest gestational age at diagnosis was 11 weeks 6 days. The mean crown-lump length was 61.9 mm; mean gestational age was 12 weeks; and mean maternal body mass index ± SD was 21.2 ± 3.9 kg/m(2). Nine fetuses had increased nuchal translucency ranging from 2.4 to 12.4 mm (mean ± SD, 6.4 ± 3.6 mm). Color Doppler flow imaging revealed biphasic bidirectional flow in the ascending aorta and aortic arch and reversed flow in the ductus venosus during atrial systole in all cases. Reversed diastolic flow was present in the umbilical arteries and thoracic aorta. All cases had complex cardiac malformations as well as extracardiac abnormalities.

Conclusions: Our study confirms that absence of the aortic valve is a rare cardiac defect that can be diagnosed by first-trimester fetal echocardiography. A "to-and-fro" flow pattern or biphasic bidirectional flow in the great arteries is a key echocardiographic feature in fetuses with absence of the aortic valve.