The Diastolic and Systolic Velocity-Time Integral Ratio of the Aortic Isthmus Is a Sensitive Indicator of Aortic Coarctation in Fetuses

Abstract

Prenatal diagnosis of coarctation of the aorta (CoA) is challenging and is affected by high false-positive and false-negative rates. The aim of this study was to identify sonographic criteria to improve the identification of fetal CoA. A retrospective review was conducted of subjects with prenatal suspicion for CoA who also had postnatal follow-up. Sixty-nine fetuses were identified with possible CoA, and 47 normal fetuses were selected as control subjects. Retrospective measurements of right ventricular/left ventricular ratio, pulmonary artery/aorta ratio, aortic isthmus (AOI) Z score, diastolic velocity-time integral (VTID), and systolic velocity-time integral (VTIS) at the AOI were recorded. Receiver operating characteristic curve analysis identified the parameter most predictive of postnatal CoA. When comparing subjects with (n=31) and without (n=38) CoA, significant differences were detected for the AOI Z score, VTID, VTID/VTIS ratio, and VTID/(VTID+VTIS) ratio (P<.001). The areas under the receiver operating characteristic curve were 0.92, 0.92, 0.78, 0.74, 0.71, and 0.68 for the VTID/VTIS ratio, VTID/(VTID+VTIS) ratio, VTID, AOI Z score (sagittal view), AOI Z score (three-vessel tracheal view), and pulmonary artery/aorta ratio, respectively. There was a 25% (95% CI, 14%-35%) improvement in the area under the curve after adding the VTID/VTIS ratio to the basic model (AOI Z score [sagittal view]), and this ratio (after transformation) showed significantly better discrimination and reclassification ability for determining CoA. The pulmonary artery/aorta ratio, VTID, VTID/VTIS ratio, and VTID/(VTID+VTIS) ratio were stable throughout the normal fetal developmental period in this study. In cases with suspected prenatal diagnosis of CoA, evaluation of spectral Doppler measurements, such as the VTID/VTIS ratio, may enhance the accuracy of diagnosis with fetal echocardiography.