Holter and Event Monitor

Holter monitors and event recorders are devices to record a person's heart rhythm over an extended period of time. Abnormalities of the heart rhythm tend to be paroxysmal and more often than not, do not occur while the patient is in the doctor's office being examined. When a patient complains of symptoms that sound like they are due to an abnormal or erratic heart rhythm, it is important to record the rhythm electrocardiographically.

There are many different types of abnormal heart rhythms. Some don't require any treatment. For those that do, the type of abnormal heart rhythm must be known in order to select the proper treatment. What works for one type of abnormal heart rhythm may be ineffective or dangerous for other types of abnormal heart rhythms. Finally, in some people, the monitor shows that heart rhythm was normal when the symptoms occurred. Then, the doctor knows that another cause for the symptoms must be sought.

A holter monitor is generally worn for 24 hours but it can be worn for longer periods of time if needed. ECG electrodes are attached to the patient's chest and are attached by wires to a small recording device which hangs by a small shoulder strap. This records a continuous ECG on a magnetic tape. The patient is also asked to keep a diary, noting the time of activities and symptoms. At the end of the recording period, the patient returns to the doctor's office where the electrodes and monitor are removed. The tape is then analyzed and the recorded heart rhythm is correlated with any symptoms the patient recorded in the diary.

Many times, the symptoms occur rarely and it's hard to catch them even with a holter monitor. For these patients, an event monitor is used. This device is similar to a holter monitor but can be kept for weeks at a time. It continuously records the heart rhythm into a temporary memory The patient is instructed to press a button on the device when the symptoms occur. When the button is pressed, the recording for the preceding few seconds as well as the subsequent few seconds is placed into a permanent memory. Otherwise, the remainder of the recordings in the temporary memory are discarded. The permanently stored recordings can be transmitted back to the doctors office over standard telephone lines for instant analysis.

What is a cardiac event monitor?1

Like Holter monitors, cardiac event monitors are another kind of ambulatory electrocardiogram (EKG, ECG) monitor. There are two different types of cardiac event monitors: Presymptom (looping memory) event monitor. This is a small device, often about the size of a pager, that attaches to your chest with adhesive electrodes. Like a Holter monitor, the presymptom event monitor records your heartbeat constantly. However, when specific symptoms of heart trouble (such as dizziness or palpitations) occur, you need to press a button on the monitor to make a permanent recording of your heart rhythm. This monitor will also save a small amount of information about how your heart was beating before the save button was pressed (presymptom recording). This feature is especially useful if you become unconscious when your heart problems occur and are not able to push the save button until after you wake up.

Postsymptom event monitor. This type of monitor is used only when symptoms of heart problems occur. Unlike other EKG monitors, a postsymptom event monitor does not have electrodes that attach to your chest. One type of postsymptom event monitor fits on your wrist like a watch. Another type of postsymptom monitor is about the size and shape of a credit card and is carried in your purse or pocket. When heart symptoms occur, you press the monitor (which contains small metal buttons that function as electrodes) against your chest while you push a button to start the EKG recording.

Cardiac event monitor or Holter monitor?

While a Holter monitor records heart activity over a longer period than an EKG in a hospital or doctor's office, you may find it uncomfortable to wear a Holter monitor for longer than 24 hours. However, you may have symptoms of heart trouble that occur even less frequently than once in a 24-hour period. In this case, your doctor may suggest a cardiac event monitor, which you may find easier to keep near you for a longer time than a Holter monitor.