In medicine, a Holter monitor (occasionally ambulatory electrocardiography device) is a portable device for continuously monitoring various electrical activity of the cardiovascular system for at least 24 hours (often for two weeks at a time). The Holter’s most common use is for monitoring heart activity (electrocardiography or ECG), but it can also be used for monitoring brain activity (electroencephalography or EEG) or arterial pressure. Its extended recording period is sometimes useful for observing occasional cardiac arrhythmia or epileptic events which 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.
When used for the heart, much like standard electrocardiography the Holter monitor records electrical signals from the heart via a series of electrodes attached to the chest. Electrodes are placed over bones to minimize artifacts from muscular activity. The number and position of electrodes varies by model, but most Holter monitors employ between three and eight. These electrodes are connected to a small piece of equipment that is attached to the patient’s belt or hung around the neck, and is responsible for keeping a log of the heart’s electrical activity throughout the recording period.
Older devices used reel to reel tapes or a standard C90 or C120 audio cassette and ran at a 1.7mm or 2mm/second speed to record the data. Once a recording was made, it could be played back and analyzed at 60x speed so 24 hours of recording could be analyzed in 24 minutes. More modern units record onto digital flash memory devices. The data is uploaded into a computer which then automatically analyzes the input, counting ECG complexes, calculating summary statistics such as average heart rate, minimum and maximum heart rate, and finding candidate areas in the recording worthy of further study by the technician or the Doctor.
-While wearing the device, avoid:
Continue your normal activities while wearing the monitor. You may be asked to exercise while being monitored if your symptoms have occurred in the past while you were exercising.
When your Doctor suggest a Holter monitor for your medical problem, you already know that is an accurate exam, so, let us play with the phrase: “Don’t hold your Holter’s examination”.