Definition of Holter monitor

Holter monitor: A type of portable heart monitor that is a small electrocardiogram (EKG) device worn in a pouch around the neck or waist. A Holter monitor keeps a record of the heart rhythm, typically over a 24-hour period, and the patient keeps a diary of activities and symptoms. The EKG recording is then correlated with the person's activities and symptoms. This type of test is useful for identifying heart disturbances that are sporadic and not readily identified with a resting EKG.