Myocardial ischemia is critical and may progress to myocardial infarction without timely and effective treatment. Myocardial ischemia is generally common in coronary atherosclerosis, myocardial bridge, coronary artery embolism and other diseases, mild cases will lead to temporary hypoxia, functional decline of cardiomyocytes, and severe cases will lead to ischemic necrosis of cardiomyocytes in the corresponding blood supply area and loss of function. 1. Coronary atherosclerosis: generally due to damage to the endothelium of coronary arteries, lipid deposition in the coronary arteries under the endothelium, calcification and so on, leading to coronary atherosclerosis. It also leads to narrowing of the coronary artery lumen. Coronary artery stenosis that exceeds 50% can trigger myocardial ischemia under exertion, emotional stress, etc., which manifests itself in symptoms such as dyspnea, chest tightness, and pain in the anterior thoracic region, or even severe pain. If not timely and effective treatment, stenosis continues to aggravate, which will lead to myocardial ischemia and angina pectoris even in the resting state, and may eventually lead to myocardial infarction. 2. Myocardial bridge: the so-called myocardial bridge refers to part of the coronary artery vessels are covered by cardiomyocytes, resulting in increased contraction of the heart, the cardiomyocytes will squeeze the coronary artery, resulting in myocardial ischemia. If the squeezing is aggravated, it may lead to complete loss of blood supply to the myocardium, which may also trigger myocardial infarction. 3. Coronary artery embolism: the so-called coronary artery embolism, refers to other parts of the thrombus, fat particles, etc., blocking part of the coronary artery blood vessels, resulting in insufficient blood supply to the coronary artery and cause myocardial ischemia, or even severe ischemia and myocardial infarction. Once myocardial ischemia occurs, it is necessary to consult a doctor in time and follow the doctor’s instructions for examination and treatment.