Principle] The coronary angiography catheter is selectively inserted into the opening of the coronary artery, and the contrast agent is injected to show the anatomical course of the coronary artery and lesions. Indications] 1. Clinical suspicion of coronary artery disease, in order to clarify the diagnosis. 2.Clinical diagnosis of coronary artery disease, according to the results of the choice of treatment (such as intervention, coronary artery bypass grafting or drug therapy). 3.Acute myocardial infarction, requiring emergency intervention or surgical treatment. Follow-up after revascularization. 5.Coronary artery condition before cardiac surgery. 6.Special occupations. [Surgical methods] (1) Vascular access: femoral artery, radial artery or brachial artery can be used. (2) Seldinger method percutaneous puncture of the artery and placement of the arterial sheath tube, discretionary heparin 2,000 ~ 3,000 U, hypercoagulable state or operation with prolonged break-in (more than lh), can be additional heparin. Frequent suction of the arterial sheath side tube, observe whether there is thrombus obstruction. (3) Send the catheter to the middle of the ascending aorta under X-ray fluoroscopy and guide wire guidance, not too deep to avoid entering the coronary artery unknowingly. After the catheter is in place, remove the guide wire, remove the air, connect the triple tee, observe the pressure curve, and confirm that the pressure curve shows good. (4) Usually, left coronary angiography is performed first, usually in the orthostatic position or left anterior oblique position, and the left coronary angiography catheter is slid downward along the aortic wall to the left coronary sinus, and the front of the catheter automatically jumps into the left main trunk in most cases. At this point, it is important to confirm that there is no abnormal change in the pressure profile and to inject a small amount of contrast to confirm proper catheter placement (avoiding overdepths or over-topping of the catheter tip). If the catheter does not enter the left coronary artery, it can be entered by slightly rotating and lifting the catheter. After the catheter is properly positioned, the C-arm is rotated to visualize the left coronary artery in a variety of positions. Commonly used positions include left anterior oblique, right anterior oblique, posterior anterior, cephalic position, and foot position with angular projection. (5) Right coronary angiography usually takes the left anterior oblique position. Send the right coronary angiography catheter along the aortic wall down to the right coronary sinus, rotate the catheter in the clockwise direction, observe the pressure and catheter pulsation, and combine with the injection of contrast medium to determine whether the catheter enters the right coronary artery anonymously. After confirming that the catheter is in the proper position, the C-arm is rotated, and the right coronary artery is visualized in various positions. Commonly used positions include left anterior oblique position and right anterior oblique position. (6) At the end of the examination, the arterial sheath tube is withdrawn and localized compression is applied to stop bleeding, usually requiring 15 to 25 min of compression and pressure bandaging. Vascular closure devices may be used as appropriate. (7) Transradial left coronary angiography can choose Juakins left (JL) or Amplatz left catheter (AL). AL is easier to maneuver, can be guided by the guidewire into the left coronary sinus, while turning the catheter counterclockwise, while pushing the catheter, so that it is close to the mouth of the left coronary artery, and then twisting the catheter clockwise, the catheter will normally automatically jump into the mouth of the left coronary artery. If it is too deep, the catheter can be turned counterclockwise again to make the catheter head recede from within the left main trunk. Right coronary angiography can be performed with either a multipurpose catheter, a Judkins right (AR) or an AL catheter.The AL catheter can also be turned around to do the right coronary artery after doing the left coronary artery, and a single catheter can be used to do both coronary arteries without having to exchange catheters. In recent years, the specially designed left and right coronary artery shared type catheter, also widely used, with a catheter to complete the left and right coronary angiography. Postoperative treatment] (1) For patients with local compression hemostasis, the limb on the puncture side should be braked for 10–24h, and sandbag compression should be applied for 6h, and the radial artery approach should be used to reduce the bed rest and hospitalization time of the patients.The symptoms, vital signs, electrocardiograms, puncture sites, and peripheral circulatory conditions of the patients should be closely observed within 24h. (2) Encourage the patient to drink water or intravenous rehydration to promote the excretion of contrast medium. Pay attention to the correction of electrolyte disorders. Outcome judgment and clinical significance] 1. Outcome judgment (1) Generally, it is considered that ≥50% stenosis of the lumen diameter of major coronary arteries and their large branches will affect the blood flow reserve, and it is a clinically significant lesion. ≥70% stenosis of LAD, LCX, and RCA lesions, and ≥50% stenosis of the left main stem lesions are categorized as serious lesions. (2) The type of lesion was determined by the degree of stenosis, location, length, angulation, eccentricity, calcification, ulceration, thrombus, dilated lesion or aneurysm, branch involvement, and curvature of the vessel proximal to the lesion. (3) Determine the severity of CAD according to the number and distribution of lesions. 2, clinical significance ① to determine the diagnosis; ② to guide the treatment; ③ to evaluate the efficacy of treatment.