Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years

OBJECTIVE: Experimental studies on fetal lambs have shown that during an in crease in the resistance to placental flow the delivery of oxygen to the br ain is preserved as long as net flow through the aortic isthmus is antegrad e. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome. STUDY DESIGN: Forty-four fetuses were retrospectively included in this stud y on the basis of an abnormal Doppler velocity in the umbilical artery. Mea n gestational age at delivery was 33.0 +/-: 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as fol lows. group A, net isthmic flow antegrade (defined as the ratio of the syst olic antegrade to the diastolic retrograde velocity integrals) (n = 39); gr oup B, net isthmic flow retrograde (n = 5). RESULTS: Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is sign ificant and leads to a relative risk of 2.05 (95% confidence interval, 1.49 -2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth. CONCLUSION: Measuring the ratio of antegrade to retrograde velocity integra ls in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.