The diagnosis of coronary artery disease is mainly based on clinical manifestations (patient’s symptoms) and examination. Coronary artery disease is highly suspected when a patient with the basis of coronary artery disease (older age, multiple risk factors) develops chest pain with the following characteristics. 1.Pain site: posterior to the sternum. 2.Radiation: to the jaw, left upper limb, left shoulder. 3.Nature: crushing, burning-like. 4, Duration: 1-5 points, not more than 15 points. 5, Triggers: exertion, cold or full meal. 6, Relief: rest, sublingual nitrates (1-3 points). Differential diagnosis Angina pectoris is differentiated from acute myocardial infarction, intercostal neuralgia and costochondritis. Myocardial infarction is differentiated from angina pectoris, acute pericarditis, acute pulmonary embolism and aortic coarctation. Coronary heart disease commonly used examination methods are: 1, electrocardiogram: electrocardiogram is the earliest, most commonly used and the most basic diagnostic methods in the diagnosis of coronary heart disease, compared with other diagnostic methods, the electrocardiogram is easy to use, easy to popularize, when the patient’s condition changes will be able to capture the changes in a timely manner, and can be continuous dynamic observation and conduct a variety of load tests to improve the diagnosis of its sensitivity, whether it is angina pectoris or myocardial infarction, have their own Whether it is angina pectoris or myocardial infarction, all have their typical ECG changes, especially for the diagnosis of arrhythmia has its clinical value, but of course there are some limitations. 2, electrocardiogram load test: mainly including exercise load test and drug test (such as pansentin, isopropyl renal test, etc.), electrocardiogram is the most commonly used simple method of clinical observation of myocardial ischemia, when angina pectoris attack, electrocardiogram can be recorded to the electrocardiogram of the myocardial ischemia of the ECG abnormalities, but many patients with coronary heart disease, despite the coronary arteries dilation of the maximum reserve capacity has declined, usually the resting coronary artery blood flow can still be maintained normal, without the rest of the patient’s coronary arteries. Blood flow can still maintain normal, no myocardial ischemia manifestation, ECG can be completely normal, in order to reveal the reduced or relatively fixed blood flow, through exercise or other methods, to give the heart a load, to induce myocardial ischemia, and then confirm the existence of angina pectoris, the exercise test for ischemic arrhythmia and myocardial infarction after the evaluation of cardiac function is also essential. 3.Dynamic electrocardiogram: It is a method to record and analyze the electrocardiogram changes of the heart in the active and quiet state continuously for a long time, and this technology was firstly used by Holter in 1947 to monitor the study of electrical activity, so it is also called Holter monitoring, conventional electrocardiogram can only record the waveforms of the resting state briefly for only dozens of times of the cardiac cycle, while the dynamic electrocardiogram can record as many as 100,000 times of the waveforms in a 24-hour period continuously. However, dynamic electrocardiogram can continuously record up to 100,000 times of electrocardiogram signals in 24 hours, which can improve the detection rate of non-sustained ectopic rhythm, especially transient arrhythmia and transient myocardial ischemic attack, thus expanding the range of electrocardiogram’s clinical application and the time of its appearance can be corresponding to the patient’s activities and symptoms. 4, nuclear myocardial imaging: according to the history, electrocardiography can not exclude angina pectoris can do this test, nuclear myocardial imaging can show ischemic area, clear ischemic site and range of size, combined with exercise test and then imaging, can improve the detection rate. 5.Coronary angiography: it is the “gold standard” for the diagnosis of coronary heart disease, which can clarify whether there is any stenosis in the coronary artery, the location, degree and range of stenosis, etc., and guide the measures to be taken for further treatment accordingly; at the same time, left ventricle angiography can be carried out for the evaluation of the cardiac function. The main indications for coronary angiography are: (1) For those who still have severe angina under medical treatment, to clarify the arterial lesions in order to consider bypass graft surgery. (2) Chest pain that seems like angina but cannot be diagnosed. 6, ultrasound and intravascular ultrasound: cardiac ultrasound can examine the heart morphology, ventricular wall movement and left ventricular function, which is one of the most commonly used means of examination, and has important diagnostic value for ventricular wall tumors, intracavitary thrombus, cardiac rupture, and papillary muscle function, etc. Intravascular ultrasound can clarify the morphology of the wall and the degree of stenosis of the coronary artery, and it is a new technology with great prospects for development. 7.Cardiac enzymology examination: it is one of the important means of diagnosis and differential diagnosis of acute myocardial infarction. Clinically, according to the sequence change of serum enzyme concentration and the elevation of specific isoenzymes and other definite enzymatic changes, it can be clearly diagnosed as acute myocardial infarction. 8, cardiac blood pool imaging: can be used to observe the dynamic image of ventricular wall contraction and diastole, for determining the ventricular wall movement and cardiac function has important reference value.