Several approaches have been proposed to reduce the risk of RAO, including anticoagulation, immediate postprocedural sheath removal, and a small sheath/radial artery ratio. Doppler ultrasound examination showed that interrupted blood flow in RA tend to occur in the proximal end rather than distal part of the artery,which was ignored by a majority of interventional cardiologists. Different insights into occlusion location may lead to different options of sheath materials, models, catheters and puncture access. Thus, the investigators designed this present study to explore the reason of radial artery endothelial dysfuction and damage and occlusion location by flow-mediated dilation (FMD) to determine the suitable method to reduce occlusion risk during TRI.

Inclusion Criteria:

• admitted for transradial catheterization.

Exclusion Criteria:

• femoral access, arterial circulatory disease, pathological Allen tests, decompensated heart failure, chronic renal failure