The Holter monitor test is used to record your child's electrocardiogram (ECG) tracing continuously for 24 hours or longer. When symptoms such as dizziness, fainting, low blood pressure, prolonged fatigue, chest pain or palpitations (fast or irregular heartbeats) continue to occur without a definitive diagnosis obtained with a resting ECG, your child's physician may request an ECG tracing to be recorded over a long period.
The Holter monitor gives the physician a better opportunity to capture any abnormal heartbeats or rhythms that may be causing your child's symptoms, especially if they occur infrequently. Abnormal heart rhythms (arrhythmias) may be intermittent and not seen during the shorter recording times of the resting or signal-average ECG.
The Holter Monitor
ECG electrodes will be placed on your child's chest, and the ECG monitor will be attached to the electrodes with lead wires. The ECG monitor is small and portable – smaller than a deck of cards. The monitor may have a shoulder strap or it may clip to a belt or pocket. You will be given instructions regarding how to:
Keep the electrodes attached to your child's skin
Check the monitor for problems
Call the doctor’s office for help
Keep the electrodes and monitor dry by not allowing your child to take a shower or tub bath (a sponge bath is usually allowed) or go swimming
Avoid situations where your child may perspire excessively, causing the electrodes to detach
Keep a diary during the procedure, noting the date and time of day of any changes in activity and symptoms your child experiences
Once your child has been connected to the monitor and you have been given instructions, your child will be allowed to return to usual activities, such as playing and going to school, unless the physician instructs you otherwise. You will be given a telephone number to call in case one or more of the electrodes comes off or if the monitor starts beeping. After 24 hours, the holter monitor is returned so that the data can be analyzed and interpreted by a cardiologist.
The Event Monitor
Event monitoring is very similar to Holter monitoring and is often performed for the same reasons. With an event monitor, an ECG electrode patch is worn on the chest, and the electrodes are connected by wire leads to a recording device. However, unlike the Holter monitor that records continuously throughout the testing period of 24 hours, an event monitor is worn for a month.
The event monitor does not record until you or your child trigger the monitor to record the ECG tracing when your child feels symptoms. An auto-trigger event monitor may be used to record rhythms when symptoms are rare or suspected to occur during sleep. The auto-trigger event monitor automatically records rhythm events and can also be manually activated if your child experiences symptoms.
When your child feels one or more symptoms, such as chest pain, dizziness, or palpitations, you or your child will push a button on the event monitor recorder. Some monitors have a feature called "memory loop recording," in which the monitor can include a recording of a short period prior to the moment you triggered the recording and afterwards. This feature can help your child's physician determine more details about the possible change in your child's ECG at the time the symptoms started, and what was happening with your child's ECG just before you or your child triggered the recorder.
Another type of monitor, called "post-event recorders," simply start recording the ECG from the moment you trigger it. Another type of monitor called ACT (ambulatory cardiac telemetry) requires no patient activation. Your doctor will determine the best monitor for your child.
After symptoms are experienced and recorded, you are instructed to send the recording to a central monitoring center. You will also keep a diary of your child's symptoms and corresponding activities, just as with the Holter monitoring procedure.