Cerebral artery flow velocity acceleration and deceleration characteristics in newborn infants

Abstract

To evaluate maturational differences in the cerebral artery blood flow velocity characteristics, we measured the middle cerebral (MCA) and basilar artery blood flow velocity and time intervals using a real-time imaging pulsed Doppler system in 39 preterm and 25 term infants. Preterm MCA and basilar artery mean Doppler spectral area under the curve were ≈22 and 25% lower than the corresponding term values, with a significant increase during gestation as revealed by regression models. Paradoxically, the mean MCA systolic acceleration and deceleration slopes were ≈28 and 18% higher in preterm than in term infants: Acceleration 701.2 ± 160 cm/s2 versus 546.4 ± 156.5/s2 (p < 0.005), and deceleration 222.2 ± 71.6 cm/s2 versus 188.2 ± 52.2 cm/s2 (p < 0.05), respectively. Similarly, acceleration and deceleration pressure half times for MCA were about 15 and 1$% shorter in the preterm (p < 0.01 and < 0.005). Multiple regression models controlling for velocity and frequency terms revealed an inverse relationship between gestational age and MCA acceleration (p < 0.005), and a positive relationship between gestational age and MCA acceleration pressure half times (p < 0.02). In preterm infants the MCA specific index of pulsatility was about 32% higher (p < 0.05) than in the term, which was also inversely relatevd to gestational age in a regression model controlling for velocity terms (p < 0.02). However, the basilar artery acceleration and deceleration slopes were not significantly different between term and preterm groups, nor showed a significant gestational age effect in the multiple regression models. The results indicate that despite a lower volume flow, the rate of rise of MCA velocity is much higher in preterm than in the term infants; during maturation the velocity waveforms assume a smoother contour. These hemodynamic characteristics could in part reflect immature vessel wall viscoe-lastic properties, particularly lack of e las t in which could result in a reduced windkessel phenomenon. © 1989 International Pediatric Research Foundation, Inc.