If a patient has pain in the left chest and back at the same time, it is usually seen for the following reasons: 1. To consider the factors of trauma, such as fracture of the sternum or ribs or contusion or sprain of the surrounding soft tissues, these conditions will lead to pain in the above area; 2. For cardiogenic diseases, such as coronary artery disease, unstable angina, heart failure, acute myocarditis, pericarditis, heart compression, this condition will also have pain in the 3, for respiratory system diseases, such as tension pneumothorax, traffic pneumothorax, open pneumothorax, acute pleural effusion, large lung infection, there will also be symptoms of pain in the left posterior sternal back at this time; 4, in addition, for intercostal neuralgia, herpes zoster pain and other diseases of the chest wall, patients will also often have symptoms of pain.