An essential tool in the diagnostic evaluation of patients with cardiac arrhythmias: The ambulatory electrocardiographic monitoring is used to help determine whether someone has an otherwise undetected heart disease; such as, an abnormal heart rhythm (cardiac arrhythmia), or inadequate blood flow through the heart.

Specifically, ambulatory electrocardiographic monitoring can detect abnormal electrical activity in the heart which may occur randomly or only under certain circumstances; such as, during sleep or periods of physical activity or stress, which may or may not be picked up by standard, short-term electrocardiography performed in a doctor's office.

The main complaint that people have with ambulatory electrocardiographic monitoring is that the monitor may be cumbersome and interfere with certain activities; especially, sleeping; however, bathing and showering are not allowed during the monitoring period.

The signals of the ambulatory electrocardiographic monitoring are recorded on a cassette tape that runs slowly for a 24 hour recording, then the tape is quickly analyzed by a machine which stops when it detects any abnormalities in the recording.