The vast majority of cerebral infarcts are caused by thrombus blockage of cerebral blood supply arteries, and brain cells are the most delicate cells in the human body, and irreversible damage occurs once blood flow is completely interrupted for 8 to 10 minutes. A large number of studies have proved that to save the brain tissue it is necessary to restore the blood flow supply in the short period of time before irreversible damage ischemic threshold and semi-dark band under normal conditions the average cerebral blood flow is 50 ml/100g/. When it drops below 30 ml/100 g/min, the patient becomes symptomatic; when it drops below 20 ml/100 g/min, neuronal electrical activity fails (electrical failure) and conduction function is lost; when it drops below 15 ml/100 g/min, the nerve cell membrane ionic pumps fail (membrane failure) and the cell enters into irreversible damage; when it drops below 10 ml/100 g/min , the cell membrane depolarizes, calcium ions are inwardly flowing, and the cell eventually enters death. In the early stage of acute cerebral infarction, blood flow is not completely interrupted, and there is an ischemic limbic zone around the central area of the infarct focus, and the neurons in this zone are in a state of electrical failure, called the semi-dark zone (Penumbra). If blood flow is restored immediately, function can return to normal; if ischemia is aggravated, cells enter membrane failure and become enlarged parts of the infarct. The theory of ischemic threshold and Penumbra brings hope for early thrombolysis and re-flow treatment of acute cerebral infarction, and the purpose of clinical treatment is to rescue the Penumbra. It is currently believed that rapid dissolution of thrombus and restoration of blood flow is the most effective and basic method. A large number of studies have proved that if blood flow is restored within 3-6 hours of vessel occlusion, cerebral infarction can still be saved. If blood flow is restored beyond this period, it is not only difficult to save brain cells, but also may cause reperfusion injury, cerebral hemorrhage, cerebral edema, which is called the “time window for treatment of reflux”. Ischemic waterfall theory In recent years, it has been found that a series of ischemic metabolic disorders caused by cerebral ischemia and hypoxia, such as energy metabolism disorders, excitatory neuromediators release, excessive calcium inward flow, and free radicals reaction, are the central links leading to ischemic brain damage, which is called ischemic waterfall. Therefore, rapid thrombolysis and re-flow is the prerequisite and foundation for successful treatment of acute phase of blockbuster cerebral infarction. Without thrombolysis and reflux, even if the most effective cerebral protection methods and drugs are used, ultimately the sustained ischemic brain tissue cannot be saved.