Holter Monitoring, Event Recorder and Implantable Loop Recorder
Holter Monitoring, Event Recorder, and Implantable Loop Recorder
Monitoring the electrical activity of the heart provides another means of diagnosing cardiovascular causes of syncope. Holter monitors are walkman-sized recording devices attached to skin electrodes. The patient wears the device for 24 to 72 hours during which time the Holter is continuously recording heart electrical activity. This is useful only if the patient has an event during the monitored period of time. Alternatively, the patient can wear an event monitor. This is similar to a Holter but is a device worn for many days – It is triggered by the patient to record memory loops during or immediately after the patient has experienced symptoms. Information is transferred to a physician with the use of telephone transmission.
The Implantable Loop Recorder (ILR) is a loop monitor that is placed in the subcutaneous tissue adjacent to the sternum. It is smaller than a pack of gum and is self-contained, not requiring any wires or connections to the heart. Implantation takes less than ½ hour to perform and is a same-day procedure. Recuperation is rapid, and the procedure is generally very well tolerated. The patient can trigger the device to record loops when symptoms occur with the use of a handheld triggering device.
The physician may choose to program the device to automatically record asymptomatic arrhythmias or arrhythmias that the patient fails to record. When a syncopal episode occurs, the patient triggers the device to record the period of time before and after the event. This is performed by placing the handheld triggering device over the ILR and depressing a button. A green light on the handheld triggering device signals successful acquisition of the event. The patient then arranges an appointment with the EP staff to interrogate the device. This interrogation should be performed as soon as possible. Interrogation allows the physician to download the recorded information and review cardiac electrical activity.
ILR implantation is performed in patients in whom history, physical, and standard tests fail to reveal a likely cause of syncope. Typically such patients have relatively infrequent syncopal episodes. Thus, external Holter monitors and event monitors are impractical and insensitive.
