Proposed mechanism for the development of angiodysplasia

This cartoon depicts one possible explanation for the development of gastointestinal angiodysplasias. Mucosal and submucosal venous drainage is intermittently obstructed by muscular contraction or increased intraluminal pressure (panels A, B, and C). After many years of intermittent obstruction, submucosal veins may become dilated and tortuous (panel D) and involve additional veins and venules draining into the system. Eventually, the capillary ring dilates and the precapillary sphincter becomes incompetent resulting in a small arteriovenous communication lesion.