It is a rare congenital disease of vessels where AVM is a tangle of abnormally interconnected arteries and veins. Capillary network is missing and arteries are directly interconnected into veins.
This direct interconnection of artery and vein is called arteriovenous shunt. This cluster of these abnormal shunts is then called a nidus.
Veins are not adapted to such high blood pressure coming from arteries. This can lead to perforation of vein cell wall and therefore to a bleeding. At the same time the higher blood flow in direction to the malformation can cause “stealing” of blood and so oxygen from surrounding healthy tissue. This insufficient blood supply can cause manifestation of hypoperfusion and tissue necrosis.
AVM can be localized in any part of body. Its size can vary from very small to so-called gigantic AVM.