Chest tightness is a subjective feeling of breathlessness or lack of breath, or in severe cases, a feeling as if a stone is pressing on the chest, or even difficulty in breathing. Chest tightness can be functional or an early symptom of organic disease. Functional chest tightness is seen in the room with no air circulation for a long time, or encounter some unpleasant things, or in the climate of low air pressure, then there is often chest tightness, fatigue, after a short time of rest, open the window or go outside to breathe fresh air, relaxation of the mind, adjust the emotions, and soon return to normal. Pathological chest tightness is caused by diseases of certain organs in the body, such as obstruction of the respiratory tract, such as tracheobronchial tumors, tracheal stenosis, external pressure on the trachea; lung diseases, such as emphysema, atelectasis, pulmonary infarction, asthma, pneumothorax, etc.; heart diseases, such as certain congenital heart disease, rheumatic heart valve disease; diaphragm lesions, such as diaphragm expansion disease, diaphragm paralysis; imbalance of fluid metabolism and acid-base balance etc. The occurrence of chest tightness in children mostly suggests congenital heart disease, myocarditis or mediastinal tumors. In young people, chest tightness mostly indicates spontaneous pneumothorax, mediastinal tumor, and rheumatic heart valve disease.