Plasma thrombomodulin concentrations in infants and children undergoing cardiac catheterization.

Circulating plasma thrombomodulin (TM) is an endothelial cell marker which may reflect endothelial injury. To find out to what extent diagnostic cardiac catheterization irritates vascular endothelium we conducted a prospective study in 91 children. Soluble TM concentrations, along with thrombin generation, were measured before, at the end of and 24 hours after cardiac catheterization. Compared to starting values, TM concentrations showed a clearly significant increase at the end of cardiac catheterization and returned to pretreatment values 24 hours later. Thrombin generation followed a similar pattern. Five out of the 91 children demonstrated resistance to activated protein C (APCR). With respect to the remaining 86 children, all five APCR cases showed increased thrombomodulin concentrations along with enhanced thrombin generation. Data from this study indicate that increased TM concentrations after cardiac catheterization in children are a sign of short-term endothelial damage. Furthermore, together with enhanced thrombin generation, elevated plasma concentration of soluble TM may reflect this receptor's possible anticoagulant properties.