Myocardial infarction is myocardial infarction, and its symptom is mainly chest pain, which is reflected in the chest pain characteristics, chest pain site, chest pain duration, relief mode, etc., which is summarized as follows. 1. Characteristics of chest pain Most of the chest pain of myocardial infarction is suffocating, pressing, etc., with a sense of dying, which may be accompanied by sweating. 2. Chest pain location The typical location of myocardial infarction is located in the precordial area or the back of the sternum, of course, there are atypical locations, located in the upper abdomen, toothache, headache and other parts. 3. Duration of chest pain Myocardial infarction lasts for a long time, and the pain will continue until the coronary artery is recanalized. It is often greater than half an hour or more. 4.Relief Myocardial infarction attack containing nitroglycerin and other drugs to expand the coronary artery, the effect is not obvious, only in thrombolysis or vascular intervention after the coronary artery recanalization, chest pain and other symptoms can be relieved. In conclusion, myocardial infarction is a critical illness, once the symptoms related to the emergence of a high degree of vigilance, the need for emergency hospital treatment.