The early symptoms of myocardial ischemia are mostly paroxysmal chest pain, which can be relieved by resting or taking nitroglycerin. Myocardial ischemia refers to the conflict between coronary blood supply and myocardial blood demand due to various reasons, so that coronary blood flow cannot meet the needs of myocardial metabolism. Causes of decreased myocardial blood supply and oxygen supply or increased myocardial oxygen demand may lead to the development of myocardial ischemic symptoms. The early symptoms of myocardial ischemia are mostly manifested as paroxysmal chest tightness and chest pain in the presence of certain triggers, which include several characteristics: 1. Triggers: There are mostly triggers for the onset of symptoms, such as going upstairs, fast walking, exertion, full meal, cold, emotional excitement, etc. 2. Site: The typical site is behind the sternum, and it may radiate to the left chest, the back of the left shoulder, and the anterior medial side of the left upper arm; it may also radiate to the neck, throat, jaw and head. 3.Nature: The nature of pain is typically crush-like, mostly accompanied by obvious chest tightness, and some patients have a sense of near death, often forcing patients to stop activities immediately. 4, duration and relief mode: the duration is usually 5-10 minutes, often not less than 1 minute, not more than 15 minutes, quiet rest or nitroglycerin containing symptoms can be relieved. 5. Some patients have atypical symptoms, such as epigastric pain and subxiphoid discomfort. The main risk factors causing myocardial ischemia are hypertension, hyperlipidemia, diabetes, smoking, obesity, etc. If the above symptoms of chest tightness and chest pain occur in patients with a history of hypertension, hyperlipidemia, diabetes, etc., or if the patient usually smokes a lot and has a relatively obese body type, this situation should be highly suspected whether the chest tightness and chest pain are caused by myocardial ischemia. The early symptoms of myocardial ischemia are mostly manifested as paroxysmal chest tightness and chest pain, and there are many triggers for the symptoms to occur. If there are also major risk factors causing myocardial ischemia, patients should go to a regular hospital for electrocardiogram or myocardial enzyme examination to exclude the possibility of myocardial ischemia.