Angiography is painless because the guide wire is inserted into the blood vessel, and the moment it is inserted into the blood vessel and the skin is opened, no pain is felt because there are no nerve endings in the remaining blood vessel, and no pain is felt because there are no nerve endings. Under normal circumstances, angiography, such as cardiac angiography, is usually performed by puncturing the arteries of the upper extremities, while angiography of the lower extremities or abdominal cavity is performed by puncturing the femoral vein or the femoral artery. In general, the pain of angiography is not as obvious as one would expect because of the presence of local anesthetic.