For pain in the chest and posterior back, consider high-risk chest pain, such as acute coronary syndrome, tension pneumothorax, aortic coarctation or pulmonary embolism, and several other diseases mentioned above. These diseases have a low morbidity but high mortality rate and should be given high priority and, once diagnosed, must be treated thoroughly in a hospital setting. For moderately dangerous chest and back pain: 1. cardiogenic diseases should be considered, such as coronary artery disease, unstable angina, acute myocarditis, acute pericarditis, and cardiac compression. 2. for respiratory diseases, such as large lung infections, pleurisy and pleural effusion, there will also be involvement-like pain in the chest and back, but this pain will change with breathing. 3. for mildly dangerous chest pain. for example, intercostal neuralgia and herpes zoster pain, there will also be pain in the above mentioned areas.