Effect of Cryoprecipitate Infusion on Factor VIII Response to Venous Congestion in Patients with von Willebrand’s Disease

In patients with Von Willebrand’s disease(VWD) venous congestion(v.c.) is un able to increase the VIIIAHF and VIIIAGN level as in normal subjects. To evaluate the effect of rise in VIIIAHF and VIIIAGN levels, 5 patients with VWD received single infusion of lyophilised cryoprecipitate(15 U./Kg) for treatment of bleeding episodes. Two v.c, at 15min and at 300min after the completion of infusion, one on each arm, was performed. VIIIAHF plasma level, raised by infusion, did not show further increase after v.c. at 15min. This finding may suggest that increased levels after v.c. in normal subjects is not achieved by activation of plasma VIIIAHF. In contrast at 300min a significant increase of VIIIAHF was obtained(F test p<0.05). On the other hand VIIIAGN high plasma level immediately after infusion showed a significant rise(F test p<0.05) after v.c. at 15min but much less at 300min when VIIIAGN is reduced. The divergence on response of VIIIAGN and VIIIAHF to v.c. at different times after infusion may support the mechanism of VIIIAGN conversion to VIIIAHF in VWD. As the plasma VIIIAHF activation appears to be unlikely, the endothelial cells may be responsable for release of AGN and AHF i.e. for conversion of AGN to AHF.