 This study will evaluate patients 18 years of age with transfusion-dependent gastrointestinal bleeding due to documented gastrointestinal vascular ectasia with or without concurrent hereditary hemorrhagic telangiectasia HHT. This study will focus on documented bleeding sites in the small bowel, including the duodenum, jejunum and ileum. Eligible patients will have endoscopically-documented sites of vascular ectasia and will have required at least 4 units of blood transfusion or episodes of intravenous iron administration over the preceding four months. 