There are many reasons for shortness of breath and chest tightness, mainly consider the following: 1. Diseases of the circulatory system, such as coronary heart disease, unstable angina, acute myocardial infarction, acute or chronic cardiac insufficiency, all of which can cause shortness of breath, shortness of breath after activity, chest tightness and chest pain, and should be further diagnosed by electrocardiogram and cardiac ultrasound. 2. Diseases of the respiratory system, such as acute bronchial The symptoms of dyspnea, shortness of breath and chest tightness will occur in asthma, pulmonary infarction, lung infection, pneumothorax and pleural effusion, and the diagnosis should be confirmed by chest CT or frontal and lateral chest radiographs. 3. Renal insufficiency and acidosis will also cause dyspnea and chest tightness.