1. In carotid endarterectomy(CEA) surgery, the dynamic changes of plasma MMP9 concentration cross CEA will be identified.
2. And the part of patients suffered particulate cerebral embolic injury, their MMP9 level will increase in the early stage after CEA.

Inclusion Criteria:

-All patients enrolled had at least ≥70% unilateral or bilateral stenosis of Internal -Carotid Artery， or those who had a <70% stenosis but obvious cerebral ischema symptoms had been existed.

Exclusion Criteria:

• Exclusion criteria included poor temporal window
• Refused to cooperate with us
• Nonatheromatous such as takayasu arteritis and fibromuscular dysplasia.

patients under CEA in the PUMCH