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Medtronic Reveal® insertable loop recorder
The World’s First Implantable Diagnostic Device
What is the Reveal Insertable Loop Recorder (ILR)?
Medtronic’s Reveal® Insertable Loop Recorder (ILR) is the world’s first implantable cardiac monitor. The Reveal ILR is used to record the heart’s rate and rhythm at the time of an unexplained episode to determine if it is related to a heart rhythm problem. The Reveal ILR can help diagnose whether symptoms like fainting, dizziness, palpitations and unexplained seizure-like episodes have a cardiovascular cause.
A study recently published in the Journal of the American College of Cardiology suggests that a cardiovascular cause may be responsible for the seizure-like episodes in some patients diagnosed with epilepsy who do not respond to medication. The study, Misdiagnosis of Epilepsy – Many Seizure-Like Episodes Have a Cardiovascular Cause, was a collaboration of neurologists and cardiologists and designed to examine the prevalence of cardiovascular cause in patients with seizure-like symptoms.
Is a Seizure the same as Syncope?
No, but it can be very difficult to distinguish between a seizure and syncope. Syncope often results in movements or behaviors that mimic seizure-like characteristics. The difference is, syncope is caused by a reduction in blood flow carrying oxygen to the brain, which often results in a fainting episode. A seizure is caused from a condition that produces brief disturbances in the normal electrical functions of the brain. A seizure can sometimes accompany a syncope (fainting) episode, and syncope can sometimes accompany a seizure.
Cardiovascular causes of syncope or seizure-like episodes can be among the most serious. If syncope has a cardiovascular cause it is important to diagnose and treat it to reduce the risk of stroke or sudden cardiac arrest.
The cause of seizure-like episodes is sometimes hard to identify because in many patients it is infrequent. Traditionally, in order to diagnose the cause of an episode a patient might undergo:
- a history and physical examination
- blood tests
- a resting 12 lead electrocardiogram (ECG),
- 24 to 48 hours of continuous ambulatory cardiac monitoring (with a Holter monitor),
- external cardiac event monitoring for up to a month
- echocardiogram (“echo”)
- tilt table testing and/or
- an electrophysiology study (EPS)
- carotid sinus massage
Other tests such as an electroencephalogram (EEG), magnetic resonance imaging (MRI), echocardiogram (“echo”) and psychiatric evaluations are sometimes also necessary, depending on what the physician suspects is the cause of fainting. While valuable, some of these diagnostic tests must be performed in the hospital and can be costly and inconvenient for the patient.
Heart-related causes of syncope or seizure-like episodes are easiest to diagnose when the heart can be monitored during an episode. In the past, that meant a patient had to have such an episode while in a doctor's office or during some form of monitoring. The infrequency of most of these patients' episodes made this unlikely. The Reveal ILR is now available to make diagnosing the cause of recurrent, infrequent episodes much easier.
How does the Reveal ILR work?
The Reveal ILR continuously monitors the rate and rhythm of the heart. It works much like a black box in an airplane, whereby vital information is recorded during the actual fainting episode and can be played back later for detailed analysis. The Reveal can continuously record the heart’s rhythm and rate for up to 14 months. It can help to determine if unexplained transient symptoms are related to a heart rhythm problem in up to 88 percent of cases, a diagnostic yield much higher than traditional methods. (Source: American Journal of Cardiology, 1998)
To store the electrocardiogram (ECG) at the time of the episode, a patient places a hand-held, pager-sized activator over the Reveal ILR after waking from an episode, and presses a button. A family member or friend also can be the one to place the activator over the patient's device to save the information. Later, a physician analyzes the stored information and determines whether the episode was caused by an abnormal heart rhythm.
What are the benefits of the Reveal ILR?
The Reveal ILR captures an ECG during the actual episode, which may allow physicians to confirm or rule out an abnormal heart rhythm more definitively than other tests. Because it can be worn continuously for up to 14 months, the likelihood of capturing heart rhythm information during an infrequent episode is probable. Diagnosing the cause of seizure-like symptoms or related symptoms with the Reveal ILR may also result in fewer physician and emergency room visits, and reduce the number of tests typically involved when trying to diagnose their cause.
There is a benefit as well in knowing if the cause of seizure-like episodes is not heart-related because it enables physicians to focus more aggressively on other possible causes. Most importantly, diagnosing the cause can lead to effective treatment more quickly.
How is the Reveal ILR implanted?
Implanting the Reveal ILR takes about 15 to 20 minutes and can be done under a local anesthetic. The physician makes an incision about 2 centimeters in length, creating a pocket the same size and shape as the Reveal ILR device, about the size of a pack of gum. Once the device is inserted in the pocket, it is programmed to record the ECG during an episode. When heart activity is recorded during an actual episode and the physician is satisfied that heart rhythm-related causes can be ruled in or out, the device can be removed. See the appropriate technical manual for additional information regarding indications, contraindications, warnings, and precautions.
What are the treatment options if the cause is determined to be heart-related?
When the cause of seizure-like episodes is properly determined, it usually can be treated. If the episodes are caused by an abnormal heart rhythm, treatment options include medication, a pacemaker or implantable cardioverter defibrillator (ICD), or catheter ablation.
After these treatments, patients can often resume normal activities without fear of suffering another episode. Such treatments not only may eliminate the episodes, but may also correct the underlying cause, which may result in better overall health and improved quality of life for patients.