AMBOSS: says MOSTLY veins, not always, also pathophys “poorly understood (a potential influencing factor is low-grade venous obstruction of submucosal veins)” (ref = https://next.amboss.com/us/article/ZS0Zy2?q=angiodysplasia#Zfb87175675ef50c92c97f63c620b1be0)
will add in extra, cuz amboss: a common degenerative disorder of GI vessels (mostly venous) that can cause GI bleeding