Right carotid artery ligation in neonates: classification of collateral flow with color Doppler imaging.

Extracorporeal membrane oxygenation (ECMO) is a lifesaving procedure for neonates that involves permanent ligation of the right common carotid artery. To determine the collateral flow patterns that develop after ligation, 58 infants underwent a total of 115 color Doppler imaging studies during (n = 54), within 1 month after (n = 36), or more than 1 month after (n = 25) ECMO. On the basis of the direction of flow in the right internal carotid artery (ICA) proximal and distal to the right posterior communicating artery (PCoA), 85 of the 115 studies were placed in one of three categories: (a) Anterior communicating artery (ACoA) dominance (n = 22), with retrograde flow in the entire right ICA, was most common during ECMO and was never seen more than 1 month after ECMO. (b) PCoA dominance (n = 47), with antegrade right ICA flow distal to the right PCoA but retrograde proximally, was common during all time periods. (c) External carotid artery (ECA) dominance (n = 16), with antegrade flow throughout the right ICA, was noted in 53% of studies more than 1 month after ECMO but in only 9% of earlier studies. Patterns changed from ACoA to PCoA to ECA dominance in 17 infants, but no change in the opposite direction was noted.