Vascular Hemostasis in Flowing Blood in Children

Abstract

This review considers differences in hemostasis among newborns, children, and adults from the standpoint of the vascular endothelium and, where appropriate, in the presence of flowing blood. Special procoagulant features of newborn hemostasis include unusually large von Willebrand factor multimers, augmented platelet transport under flow conditions, and greater ability of newborn endothelium to generate tissue factor. Special anticoagulant features in the newborn include increased vessel wall glycosaminoglycan activity, elevated α₂-macroglobulin, and increased percentage of free protein S. The net effect of the differences is that hemostasis is generally achieved in all age groups but is developmental in nature. In addition to congenital hypercoagulable states and catheter placement, developmental vascular anomalies appear to constitute a thrombotic risk, at least in some children (and possibly adults).

Keywords:

Endothelium - hemostasis - shear stress - newborns - platelets - vascular anomalies