Ambulatory electrocardiography (ECG) involves the utilization of a wearable device known as a Holter monitor to record the electrical activity of the heart. This device consists of electrodes attached to the chest. Typically worn for a minimum of 24 hours, the Holter monitor is capable of detecting intermittent arrhythmias, which are abnormal heart rates and rhythms. It is also employed to evaluate the functioning of a cardiac pacemaker. Whenever symptoms arise, the wearer can press a button on the monitor to mark the recording. The captured data can then be analyzed later to determine whether the occurrences of arrhythmia coincide with the reported symptoms. In certain instances, patients can transmit the recorded data over the telephone using telecardiography, a process that involves sending the electrical impulses to a remote location for analysis.