DDAVP SHORTENS THE PROLONGED BLEEDING TIMES OF PATIENTS WITH SEVERE VONWILLEBRAND DISEASE TREATED WITH CRYOPRECIPITATE - EVIDENCE FOR A MECHANISM OF ACTION INDEPENDENT OF RELEASED VONWILLEBRAND-FACTOR

After infusion of cryoprecipitate, the very prolonged bleeding time of patients with severe von Willebrand disease (vWD) is shortened but not always normalized in spite of normalization of plasma von Willebrand factor (vWF) levels. Therefore treatments that further improve primary hemostasis in severe vWD patients are needed. Since DDAVP shortens the bleeding time in a variety of bleeding disorders, we investigated in a double-blind, placebo-controlled crossover study the effects of the intravenous (IV) infusion of DDAVP (0.3 μg/kg) on the bleeding times of 10 patients with severe vWD treated with cryoprecipitate. Their very prolonged bleeding times (>30 minutes), partially corrected by the infusion of cryoprecipitate (14 ± 2 minutes, mean ± SEM), were further shortened by the administration of DDAVP (9 ± 2 minutes, P < .01) but not of saline (15 ± 3 minutes, ns). Plasma vWF levels, raised from unmeasurable to normal values by cryoprecipitate, were not changed after DDAVP or saline. The defective deposition of platelets from eight patients onto human umbilical artery subendothelium was increased but not normalized by cryoprecipitate and was not significantly affected by DDAVP or saline. Therefore the infusion of DDAVP after cryoprecipitate may be of clinical benefit for management of bleeding episodes in severe vWD patients. Since severe vWD patients do not have releasable tissue stores of vWF, DDAVP must shorten their prolonged bleeding times independently of released vWF.