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.