Acquired von Willebrand factor deficiency has been described in patients with aortic valve stenosis due to high shear forces developed during passage through the narrowed valve orifice, which determines structural changes in this molecule. Similar flow conditions are present in patients with an aortic prosthesis that presents a patient-prosthesis mismatch. Patient-prosthesis mismatch is described by the smaller effective orifice area of the prosthesis than the native valve, which would probably determine similar changes in the molecules of the von Willebrand factor, leading to acquiring von Willebrand deficiency.