Also known as an ambulatory ECG monitor, a Holter monitor records your heart rhythms for an entire 24 or 48 hour period. Wires from electrodes on your chest go to a battery-operated recording device carried in your pocket or worn on a belt or shoulder strap. While you are wearing the monitor, you will keep a diary of your activities and symptoms. Your doctor will compare the diary with the electrical recordings to help determine what triggers your symptoms.
When an extended period of monitoring is required, more specialized equipment called an "Event Recorder" can be used. This mode of monitoring is especially useful for patients who have very infrequent symptoms.
There are no risk factors associated with holter monitoring.
What to Expect Before the Test
There is no need for fasting or any other special preparation. Take all your prescribed medications as usual and record them in the diary provided. Wear loose fitting clothes when coming to the hospital.
What to Expect During the Test
Surface electrodes will be placed on the upper chest (pictured above). The electrodes will be connected to a recorder (the size of a small cassette player), which will be strapped around your waist. You will wear it continuously for 24/48 hours as requested by your physician. Please do not remove the electrodes on your own during the recording.
You will be asked to keep a diary to record all your activities and any symptom with the exact time of their occurrence. It is a good idea to synchronize your watch with the timer on the recorder. Please carry out all your activities as usual except for bathing.
You will be advised to return to the hospital at a given time to have the recorder removed for analysis.
What to Expect After the Test
After the prescribed testing period is over, the recorded results are analyzed. Depending on the results, further testing or treatment (e.g., taking medications called antiarrhythmics) may be advised.
No follow-up is required after holter monitoring.