Transesophageal echocardiography is the placement of an ultrasound probe into the esophagus to observe the structure and function of the heart. It provides a clearer view of certain cardiac structures, such as the atrial septum, heart valves, atria and ears, compared to a normal transthoracic echocardiogram. Indications: 1. When there is a long-term fever and infective endocarditis is suspected; 2. When there is a defect in the atrial septum and the transthoracic echocardiogram is unable to clarify whether it can be blocked; 3. When there is a history of atrial fibrillation and the presence of atrial and otocardial thrombus is clarified; 4. Patients need to fast before the examination, and also need to exclude esophageal ulcer, tumor and other diseases by barium meal imaging, and need to make an appointment in advance.