There are many causes of chest tightness, chest pain and dyspnea, and the common causes are mainly the following: 1. coronary heart disease, acute myocardial infarction, patients with acute myocardial infarction will have chest tightness and chest pain, and if combined with acute left heart failure, they will have dyspnea and cough pink foamy sputum in severe cases. Patients feel unable to breathe in the horizontal position, and can improve after sitting up.2. Pneumonia and lung infection should be considered, especially patients with lobar pneumonia will have chest pain and dyspnea, and frontal and lateral chest films can show inflammation of the lung lobes.3. Pulmonary infarction, patients with pulmonary infarction will also have chest tightness, chest pain and dyspnea, and patients will have significantly elevated D-dimer.