The most common cause of heart tightness is myocardial ischemia, and the most common cause of myocardial ischemia is coronary heart disease, which includes angina pectoris, myocardial infarction, and other types. For patients with angina pectoris, the typical symptom is exertional angina pectoris, which is often induced by tightness, stuffiness, and discomfort in the middle and lower sternum of the precordial area under emotional excitement, exercise, and exertion. For patients with angina pectoris, the pain often lasts for 1-5 minutes, up to 15 minutes, and can be relieved by resting or taking nitroglycerin, while for patients with myocardial infarction, the pain is severe and long-lasting, often exceeding half an hour, and can not be relieved by resting or taking nitroglycerin, and can be accompanied by symptoms related to nausea, vomiting, cold sweating, lowered blood pressure, shock, heart failure, and so on.