Myocardial ischemia, a pathological condition in which blood perfusion to the heart is reduced, resulting in decreased oxygen supply to the heart and abnormal energy metabolism in the myocardium, which is unable to support the normal work of the heart. Myocardial ischemia can be detected by ECG, cardiac ultrasound and coronary CT angiography. 1. Electrocardiogram: Electrocardiogram and dynamic electrocardiogram are mainly used to observe whether there is any ischemic ST change on the electrocardiogram, so as to indirectly determine whether there is myocardial ischemia. 2. Cardiac ultrasound: cardiac ultrasound is mainly to check whether there is any abnormality in the structure and function of the heart. If ischemia is more serious, it will cause myocardial contraction force to decrease, and when doing cardiac ultrasound, it will indicate segmental hypermobility, which is a strong indication of myocardial ischemia. 3. Coronary artery CT angiography: It is the most intuitive and direct examination to diagnose myocardial ischemia by injecting contrast agent under X-ray and directly observing whether there is any stenosis in the blood vessels of the heart and to what extent the stenosis is. Patients with myocardial ischemia may suffer from tightness or constriction-like pain in the retrosternal or precordial area when they are tired or nervous, radiating to the left shoulder and left upper arm, lasting 3-5 minutes and relieved by rest, accompanied by profuse sweating; or chest tightness, palpitation, and shortness of breath when they are physically active, relieved by rest. It is recommended to go to the hospital for relevant examination in time.