If a patient has symptoms of pain on the left side of the heart when breathing, the following points should be considered: First, cardiogenic diseases are considered, such as unstable angina pectoris in coronary artery disease, or acute myocarditis or pericarditis, when the symptoms of pain in the heart will appear, which will gradually worsen with breathing. In addition, arrhythmias caused by various reasons will also have chest tightness, shortness of breath and chest pain, which will worsen with breathing. Secondly, if the patient has a large pneumothorax, pleurisy, or pleural effusion caused by various factors, at this time, the patient will also have a painful feeling on the left side of the heart with a deep breath. Third, if the patient suffers from trauma, such as fracture of the sternum or ribs, contusion of the surrounding soft tissues, stretching injury, sprain and other factors, it will also lead to the symptoms of pain with deep breathing. Fourth, if the patient develops cardiac neurosis, especially when there is a disorder of vegetative nerve function, this will also be manifested.