Doppler changes in the main fetal brain arteries at different stages of hemodynamic adaptation in severe intrauterine growth restriction

Abstract

To evaluate changes in the temporal evolution and regional distribution of arterial brain Doppler parameters in relation to different stages of hemodynamic adaptation in fetuses with severe intrauterine growth restriction (IUGR). Thirty-six fetuses with severe IUGR (<or= 32 weeks of gestation) and abnormal umbilical artery (UA) pulsatility index (PI) (mean > 2 SD) were evaluated longitudinally with pulsed Doppler ultrasound at four different hemodynamic stages: Stage 1 (n = 36), mean UA-PI > 2 SD or absent UA end-diastolic flow; Stage 2 (n = 34), abnormal middle cerebral artery (MCA) PI (mean < 2 SD); Stage 3 (n = 30), reversed UA end-diastolic flow; Stage 4 (n = 12), absent or reversed atrial flow in the ductus venosus. In addition, 36 normally grown fetuses were studied for comparison. PI and time-averaged maximum velocity (TAMXV) in the MCA and the anterior cerebral (ACA), pericallosal (PER) and posterior cerebral (PCA) arteries were measured. In IUGR fetuses, PI values from all arteries were significantly reduced at Stage 2. At Stages 3 and 4, ACA-PI and PCA-PI did not change further, whereas MCA-PI and PER-PI showed a slight increase. In the ACA, MCA and PER, TAMXV in Stage 2 increased significantly. In Stages 3 and 4, ACA and PER-TAMXV remained unchanged, whereas MCA-TAMXV showed a slight decrease, mirroring the PI values. PCA-TAMXV values were similar to controls at all stages. In IUGR fetuses, the brain arteries differ in the magnitude and time sequence of Doppler parameters in relation to systemic hemodynamic adaptation, suggesting the existence of regional brain redistribution processes.