Because many bradyarrhythmias (arrhythmias) occur only intermittently, devices that record the EKG for longer periods (24 to 48 hours) are more effective in finding an arrhythmia than a single 10-second EKG done in a doctor's office. Ambulatory EKG monitors (Holter monitors) will continuously record your heart rhythm and can be worn while you do your usual activities. A technologist or doctor can then review the recording to determine whether you had a bradyarrhythmia during the monitoring period.

Keeping track of symptoms

Your doctor will likely tell you to keep a journal of your activities and symptoms while you are wearing the Holter monitor so that any arrhythmia noted can be matched to your symptoms. If you have symptoms that suggest an arrhythmia, but you have a normal heart rhythm during the symptoms, in most cases that would mean that an arrhythmia is not the cause of the symptoms.

What are the limitations of a Holter monitor?

Portable EKG monitors are useful if you have frequent symptoms that your doctor thinks are cause by an arrhythmia. Obviously, if no symptoms or arrhythmia occurs while the monitor is being worn, the test is not as helpful. If your symptoms occur only rarely, even a 48-hour period of monitoring is not likely to be useful. Prolonged EKG monitoring may also be useful for monitoring the effectiveness of treatment for the arrhythmia and for evaluating the function of a pacemaker.

What is an event monitor?

Event monitors are similar to ambulatory EKG monitors (Holter monitors) except that they are worn for weeks at a time. This type of device continuously monitors your heart rhythm but stores only several minutes of the recording in its memory. If you have a symptom that suggests a bradyarrhythmia (a slow arrhythmia), you can activate the device, which then permanently stores a recording of your heart rhythm for several minutes before and after the event.

The stored information can then be sent over the telephone to a lab that will analyze the recording and discuss the results with your doctor. This type of monitor can be very useful if your symptoms do not occur often. Like the Holter monitors, event monitors can be helpful in documenting that you have an arrhythmia, diagnosing the particular type of arrhythmia, and determining the relationship (if any) of the arrhythmia to your symptoms.