Coronary angiography is an effective method for diagnosing coronary artery disease. A catheter is inserted through the femoral, radial, or other peripheral arteries to the ascending aorta, and then the left or right coronary artery is explored for insertion and contrast is injected to visualize the coronary arteries. This will reveal the anatomical abnormality of the coronary artery and the location, extent and scope of the obstructive lesion. Although other tests such as electrocardiogram can also diagnose coronary artery disease, sometimes they are not accurate, and the most accurate method to diagnose coronary artery disease is coronary angiography. Coronary angiography is the only method that can directly observe the morphology of coronary arteries, and is known as the “gold standard” in the medical community. Coronary angiography has important clinical significance: (1) To clarify the diagnosis of coronary artery disease: For patients with atypical angina pectoris symptoms that are difficult to diagnose clinically, especially those with poor therapeutic effect, as well as middle-aged and elderly patients with enlarged heart, severe arrhythmia, heart failure, abnormal electrocardiogram and suspected coronary artery disease or malformation, but the non-invasive test results cannot confirm the diagnosis, coronary angiography can provide a strong diagnostic basis. . (2) For guiding treatment: For patients with clinically confirmed coronary artery disease who are considered for percutaneous transluminal coronary angioplasty (PTCA) or aortic-coronary artery bypass grafting due to poor conservative medical treatment, coronary artery and left ventricular angiography must be performed first to clarify the site and degree of coronary artery stenosis and the function of the left ventricle, so as to correctly select the indications and formulate the treatment plan.