- In medicine, a Holter monitor (also called
an ambulatory electrocardiography device), named after its inventor, Dr. Norman J. Holter, is a portable device for
continuously monitoring the electrical activity of the heart for 24 hours or more. Its extended recording period is sometimes useful for observing occasional cardiac arrhythmias that would be difficult to identify in a shorter period of time.
For patients having more transient symptoms, a cardiac event monitor which can be worn for a month or more can be used.
Much like standard electrocardiography (ECG), the Holter monitor records electrical signals from the heart via a series of electrodes attached to the chest. The number and position of electrodes varies by model, but most Holter monitors employ from three to eight. These electrodes are connected to a small piece of equipment that is attached to the patient's belt, and is responsible for keeping a log of the heart's electrical activity throughout the recording period.
- Cardiac event monitors are small portable devices worn by a
patient during normal activity for up to 30 days. The device has a recording system capable of storing several minutes of the individual's
electrocardiogram (EKG) record. The patient can initiate EKG recording during a symptomatic period of arrhythmia. Cardiac event monitors have primarily been used to diagnose and evaluate cardiac arrhythmias. These monitors are particularly useful in obtaining a record of arrhythmia that would not be discovered on a routine EKG or an arrhythmia that is so infrequent that it is not detected during a 24-hour period by a Holter monitor.