Small Bowel Angiodysplasia

A 74-year-old woman with moderate aortic stenosis (gradient 45 mmHg) and chronic kidney disease stage 3 presents with a 6-month history of recurrent iron deficiency anemia and melena. Upper endoscopy and colonoscopy are negative. Video capsule endoscopy of the small bowel reveals multiple discrete cherry-red vascular lesions with characteristic fern-like arborizing capillaries radiating from central feeder vessels, distributed throughout the jejunum and proximal ileum. Several lesions show fresh red halos with active oozing. The structure marked **A** in the diagram represents these lesions. Which of the following best explains the pathophysiology linking her aortic stenosis to bleeding from these lesions?

A 74-year-old man with severe calcific aortic stenosis (valve area 0.8 cm², mean gradient 45 mmHg) presents with a 6-month history of recurrent melaena and symptomatic iron-deficiency anaemia (Hb 7.2 g/dL, MCV 68 fL). Repeated upper GI endoscopy and colonoscopy with good bowel preparation revealed no bleeding source. Video capsule endoscopy identifies the lesion marked **B** in the diagram—multiple small cherry-red flat vascular lesions in the jejunum and proximal ileum with tortuous dilated thin-walled submucosal vessels radiating with a fern-like margin. One lesion shows active oozing. Which of the following best explains the pathophysiology linking this lesion to his aortic stenosis?