The pain in the middle of the chest may be caused by two factors: 1. It may be caused by a sterile inflammation of the sternum in the middle of the chest and the rib cartilage between the ribs. If the inflammation is strong, there will also be local redness, swelling, heat and pain, and the pain will usually appear or worsen when breathing deeply or when the thorax is moved with force. 2. There may be pressure pain under the mastoid process below the chest, and the pressure pain in this area may be a problem of the upper gastrointestinal tract, commonly acute or chronic gastritis, gastric ulcer, duodenal ulcer, etc. If the pain is sudden and severe, accompanied by abdominal muscle tension and rebound pain throughout the abdomen, there may be ulcers and perforation of the upper gastrointestinal tract. However, it is important to note that if no pressure is applied in the middle of the chest, pain can also occur and resemble a crushing pain. It is important to suspect acute heart disease, such as acute myocardial infarction, angina pectoris, which can be diagnosed by an electrocardiogram and a blood test for troponin.