6A_02: Prenatal detection of coarctation of the aorta using Doppler velocimetry to detect a diastolic tail in the aortic isthmus

Abstract

To validate the use of a diastolic tail in the aortic isthmus, representing continuous flow in diastole, as a marker of coarctation of the aorta in the fetus. A retrospective analysis of 6 years of fetal echocardiogram studies were analysed. All studies had been reported as probable coarctation of the aorta in fetuses between 16 and 37 weeks gestation. A STIC volume of the fetal heart with colour Doppler was analysed using 4D-View. In the transverse view of the aortic and ductal arches M Mode was applied to detect continuous flow in diastole at the aortic isthmus. The investigator was blinded to the postnatal diagnosis of the fetus. A further 68 control cases were obtained prospectively using both colour and B flow Doppler between 16 and 37 weeks gestation. M mode of the aortic isthmus detected a diastolic tail in 1 case at 35 weeks gestation, in which there was no other reason to suspect coarctation of the aorta. 79 cases of probable coarctation of the aorta were identified. Good quality imaging of the aortic arch in transverse view, with adequate colour fill was obtained in 68 cases. Of these 68 cases the mean gestation was 28 weeks (16 to 37 weeks). Using M mode at the aortic isthmus a diastolic tail was detected in 3 cases. Of these 3 cases 1 had a postnatal diagnosis of coarctation of the aorta however the other 2 cases did not. All 3 positive cases with a diastolic tail were greater than 30 weeks gestation. Postnatal follow-up information was available for 54 out of the 68 cases. A diastolic tail in the aortic isthmus has recently been hypothesised and reported as a strong marker for detecting coarctation of the aorta in the fetus. Previously this test, which uses the high systolic velocity at the site of the coarctation giving continuous flow throughout the cardiac cycle (diastolic tail) has only been used after birth as a marker of severe coarctation. Our retrospective evaluation did not support the use of a diastolic tail for prenatal diagnosis of coarctation of the aorta.