Echocardiography is a non-invasive test that is harmless to the human body. The patient should be relaxed during the test, try to keep breathing calmly and cooperate with the doctor to complete the test. It is not necessary to fast for general cardiac ultrasound examinations, but you may eat appropriately but not too much. Transesophageal ultrasound should be performed only after fasting for at least eight hours. Cardiac ultrasound is the first choice for most cardiovascular diseases and is of great value in diagnosing coronary heart disease, heart valve disease, cardiomyopathy, congenital heart disease, pericardial disease and large vessel disease.