Ultrasound of the heart can monitor the rhythm and frequency of the heartbeat, which can assist in the diagnosis of arrhythmias. However, cardiac ultrasound is not the gold standard for arrhythmias. To detect or diagnose arrhythmias, cardiac Holter, or ambulatory electrocardiogram, should be performed, which is a diagnostic method to clarify the cause of the arrhythmia. If the arrhythmia is considered to be caused by coronary artery neck spasm or stenosis, coronary angiography or coronary CT evaluation is also required. Therefore, the arrhythmia cannot be examined by cardiac ultrasound, and other tests should be performed to make a comprehensive judgment.