Normally, the doctor may prescribe an ambulatory electrocardiogram during a hospital visit. Ambulatory electrocardiogram is now a relatively common test to monitor tachyarrhythmias, to monitor the pattern of onset and termination of arrhythmias, and whether the patient has preexcitation syndrome, pathological sinus node syndrome and atrioventricular block. Ambulatory electrocardiography can observe slow arrhythmias for the presence of sinus node dysfunction and the presence of fast-slow syndrome, which can provide a reference for the use of medications and the need for subsequent pacemakers. The ECG can also be used to assess the effects of arrhythmogenic drugs, side effects and arrhythmogenic effects when antiarrhythmic drugs are currently being taken, to assess the dosage and usage of arrhythmogenic drugs, and whether the patient needs to increase, adjust, reduce or stop the dosage. Based on the results of the ECG, certain tachyarrhythmias and slow arrhythmias can also be referenced for the types of pacemakers that need to be installed. Unlike ordinary ECG, ECG can be worn on the body for continuous recording and editing to analyze the electrical activity of the heart, independent of the person’s rest and activity, and the collected ECG signal can reach 100,000 beats/24 hours, making it a non-invasive, important and excellent screening method in the cardiovascular field.