Holter monitoring or ambulatory E.C.G., is a recording of the electric activity of the heart. It is done while the patient is walking or moving around, wearing a small tape recorder called a Holter monitor.

Holter monitering helps identify occurrences of abnormal electrical activity in the heart. Your doctor uses this form of test to help explain what is causing your palpitations, dizzy episodes or fainting attacks. The heart’s electrical abnormalities may occur spontaneously or after emotional stress or exercise. Some of the electrical disturbances may be life-threatening. By using a diary of the occurrence of events and at the same time recording the hearts electrical activity your doctor may be able to learn what causes your symptoms. The holter monitor is not only able to detect abnormal heart rhythms but also to detect if the heart is suffering from lack of oxygen by doing ST segment analysis. Holter monitoring is done continuously for either 24 or 48 hours as a person goes about his or her normal daily activities.

In addition to holter monitoring, your doctor may refer you for an event monitor which is a variant of a holter monitor. It is worn for much longer periods up to 2 weeks and unlike a holter monitor is designed only to record pre-selected abnormal rhythms. You may also press a button on this monitor if you feel some symptoms and it will record what was happening at that time.Even longer lasting heart monitors may be advised but these are implanted surgically under the skin and are left for some months to capture an arrhythmia. these are reserved for patients with infrequent but concerning symptoms such as sudden collapse for no apparent reason.