The emergence of brain infarction depends to a great extent on the status of collateral blood circulation and is associated with hemodynamic instability. This kind of brain infarction is usually found in border vascular zones. Infarction of borderline fields arises between vascular territories ACA and ACM or between ACM and ACP, deep paraventricular infarcts in internal border zones, wound or triangular cortical infarcts, as well as major infarctions involving the entire irrigated territory of ACM.