Hypoxic Preconditioning on Patients

Inclusion Criteria: 1. Informed written consent from the patient. 2. Han nationality, age \>18 years. 3. Carotid artery stenosis on at least one side, measuring more than 70% by ultrasonic detection and requiring carotid artery stenting or a carotid endarterectomy. 4. Long-term residence at an altitude of \<100 m (the altitude of Tianjin is 2-5 m). 5. Not having been to an altitude ≥1500 m in two years. Exclusion Criteria: 1. Planned vessel sacrifice as the primary modality for ischemic cerebrovascular treatment. 2. Systemic blood disease before intervention. 3. Regular physical activity exercise: frequency \>1 time/week, duration \>20 min. 4. History of brain disease or history of stroke or transient ischemic attack within the previous six months. 5. History of heart, liver, kidney or lung disease. 6. History of hypertension and poor blood pressure control, with blood pressure \>160/90 mmHg. 7. Pregnancy.