Acquired von Willebrand syndrome in aortic stenosis

Aortic stenosis can cause excessive bleeding by damaging proteins involved in blood clotting, according to a study of 50 patients. In patients with aortic valve stenosis, the aortic valve in the heart is narrower than normal. This damages a large blood clotting protein called von Willebrand factor as it passes through the valve and this in turn causes excessive bleeding. This explains why blood clotting returns to normal in many patients who have the valve replaced with an artificial valve.