Cerebrovascular disease capillary bed separates arteries from veins, which protects the veins from the higher blood pressures that occur in arteries. In arteriovenous malformations, arteries are directly connected to veins, which increases the risk of venous rupture and hemorrhage. Arteriovenous malformations in the brain have a 2–4% chance of rupture each year. However, many arteriovenous malformations go unnoticed and are asymptomatic throughout a person's lifetime. A germinal matrix hemorrhage is bleeding into the brain of premature infants caused by the rupture of fragile blood vessels within the germinal matrix of premature babies. The germinal matrix is a highly vascularized area within an
Circulatory anastomosis Circulatory anastomosis A circulatory anastomosis is a connection (an anastomosis) between two blood vessels, such as between arteries (arterio-arterial anastomosis), between veins (veno-venous anastomosis) or between an artery and a vein (arterio-venous anastomosis). Anastomoses between arteries and between veins result in a multitude of arteries and veins, respectively, serving the same volume of tissue. Such anastomoses occur normally in the body in the circulatory system, serving as backup routes for blood to flow if one link is blocked or otherwise compromised, but may also occur pathologically. Arterio-arterial anastomoses include actual (e.g., palmar and plantar arches) and potential varieties (e.g., coronary