Pathophysiology
AVMs are an abnormal connection between the arteries and veins in the human brain. Arteriovenous malformations are most commonly of prenatal origin. The cause of AVMs remains unknown. In a normal brain oxygen enriched blood from the heart travels in sequence through smaller blood vessels going from arteries, to arterioles and then capillaries. Oxygen is removed in the latter vessel to be used by the brain. After the oxygen is removed blood reaches venules and later veins which will take it back to the heart and lungs. On the other hand when there is an AVM blood goes directly from arteries to veins through the abnormal vessels disrupting the normal circulation of blood.
Read more about this topic: Cerebral Arteriovenous Malformation