A Holter monitor is a 24-hour electrocardiogram (ECG or EKG). An ECG is a tracing of the electrical activity of the heart that appears as lines on paper.
If you place a Holter monitor on a patient, you are able to see the ECG trace for a whole day. This is helpful to see if there are any abnormalities in the electrical activity of the heart (abnormal heart beats) over the course of a day.
In addition, a Holter monitor is helpful to determine if an abnormal heart beat occurs with a certain activity (like sleep or exercise or excitement). The owner of the patient with the Holter monitor keeps a Holter diary and records the activity of the patient. Then, the ECG can be evaluated at the time of the activity to determine if there is an abnormal heart beat.
