What are angiodysplasia?
Normally arteries are connected to veins via intervening capillaries. Arteries are exposed to high pressure because they receive blood pumped from the heart and have a relatively thick, muscular wall to contain blood under high pressure without bursting or leaking. The very narrow capillaries normally dissipate the high pressure in the arterial system through friction to produce a low pressure in the venous system. Veins typically have thin walls because they are exposed to low pressures. Angiodysplasia is a vascular tuft or tangle of vessels with a central feeding artery directly connected directly to veins without intervening capillaries. Angiodysplasia is sometimes called arteriovenous malformation to describe this vascular anomaly. In angiodysplasia the veins distal to the feeding artery are exposed to abnormally high pressures because of the absence of capillaries and can become leaky, manifesting clinically as occult or gross bleeding.