Introduction. Surgical treatment of congenital heart defects in children is associated with a high incidence of early thrombotic complications. Violation of the ratio of von Willebrand factor (vWF) and ADAMTS13 metalloproteinase activity is one of the components of changes in the hemostasis system.Aim: to study changes in the vWF-ADAMTS13 system in patients with obstructive congenital heart defects.Materials and methods. The prospective observational cohort study included 18 newborns with isolated obstructive CHD (congenital valvular aortic stenosis, isolated coarctation of the aorta). The activity of vWF and ADAMTS13 was determined in all patients, and the dynamics of fibrin formation and thrombin generation were evaluated. The relationship between hemodynamic parameters and the Reynolds number with laboratory parameters of the blood coagulation system before correction of congenital heart defects was studied.Results. The activity of von Willebrand factor varied from 32.1 to 242.0 %. The distribution of ADAMTS13 activity ranged from 0.83 to 1.56 IU/ml. The values of von Willebrand factor activity correlated with the average platelet volume, the initial and steady-state growth rate of the fibrin clot, as well as its size, the time to reach the peak of thrombin (negative correlation) and the rate of thrombin propagation. ADAMTS13 activity values correlated with the aortic valve annulus diameter, aortic arch and isthmus diameter, Reynolds number, and fibrin clot growth retardation. In a univariate regression analysis, aortic valve size (β = 0.540, p = 0.021) and aortic isthmus diameter (β = 0.909, p = 0.001) had predictive value for ADAMTS13 activity. The Reynolds number predicted vWF/ADAMTS13 ratio (β = -0.529, p = 0.024). Plt/vWF made it possible to predict Vi over 56 μm/min (AUC = 0.810 (95 % CI 0.605–1.014), p = 0.003, cut-off = 6.44).Conclusion. ADAMTS13 activity increases with increasing shear stress, and the dynamics of fibrin formation depends on vWF activity. In the state of the vWF/ADAMTS13 system, two variants can be distinguished, characterized by an increase in inhibitor activity and its depletion with an increase in vWF activity. The Plt/vWF ratio makes it possible to predict the occurrence of prothrombotic states in patients with obstructive forms of CHD, which in turn, makes it possible to recommend monitoring this ratio in children who are in their first few months of life.
