Abnormal von Willebrand factor in bleeding angiodysplasias of the digestive tract

Background & Aims: Involvement of an abnormal von Willebrand factor in the bleeding expression of gastrointestinal angiodysplasias has been suggested but not assessed by prospective studies. Methods: To address this issue, 27 patients with either nonbleeding (group A, n = 9) or bleeding (group B, n = 9) digestive angiodysplasias or telangiectasias or diverticular hemorrhag e (group C, n = 9) were enrolled. In all patients, an analysis of von Wille brand factor and a screening for the most common disorders associated with an acquired von Willebrand disease were performed. Results: In all patients from groups A and C, von Willebrand factor was normal, and no underlying d isease could be found. In contrast, all but 1 patient from group 9 had a va riable selective loss of the largest multimeric forms of von Willebrand fac tor, associated in 7 cases with a stenosis of the aortic valve. Conclusions : This study indicates that most patients with bleeding angiodysplasia or t elangiectasia have a deficiency of the largest multimers of von Willebrand factor induced by a latent acquired von Willebrand disease. Because these m ultimers ave the most effective in promoting primary hemostasis at the very high shear conditions related to these vascular malformations, we suggest that their deficiency is likely to contribute to the bleeding diathesis.