An ambulatory electrocardiogram (ECG) is a small, portable medical device that records the electrical activity of the heart. It is used to detect irregularities in the heart rhythms of patients during their daily activity. Usually a noninvasive recording device, the ECG uses skin electrodes to detect the patient's heart activity. These electrodes are usually applied to the skin with adhesive tabs and then connected to the ambulatory ECG monitor, which is usually clipped onto the belt or worn in a pouch, but it also can be attached to the ambulatory ECG device itself. The patient then goes about his or her normal daily activity with the ECG device in tow, recording any changes that might occur in the his or her heart rate or rhythms.
There are two basic categories of ambulatory ECG. These are the continuous recorder and the intermittent recorders. Intermittent recorder ECG machines are further divided into loop recorders and event monitors.
Continuous recording ECG devices monitor the patient's heart activity over an extended period of time. This time period is usually 24-72 hours but might be much longer. Certain types of long-term ambulatory ECG devices can be surgically implanted in the chest and remain there for a year or more.
Intermittent recording ambulatory ECG devices are used when patients have infrequent heart arrhythmia. With this type of ECG device, recording does not happen all the time. Instead, recording occurs only when the patient is experiencing symptoms.
The intermittent ambulatory ECG requires a certain amount of patient interaction. In the case of the loop recorder, the patient must press a button on the recording device when he or she experiences the symptoms of heart trouble. This signals the machine to record additional information about the heart's rhythms and electrical function during the episode.
With an event monitor, the patient must also activate the recording process. This ambulatory ECG differs from the loop recorder and other ambulatory ECG devices in the fact that the electrodes are not attached to the patient's body with adhesive tabs. The event monitor type of ambulatory ECG is a small device that can be worn like a watch or carried in a purse or pocket. When the patient experiences symptoms of heart arrhythmia, he or she presses the button to activate the device and places the electrodes of the device against the skin.