The implantable loop recorder (ILR) is a small (one-third the size of a AAA battery) monitor that is implanted with a simple procedure using local anesthesia. The device is injected under the skin in front of the heart through a small incision and has a battery life of 2-3 years.
It continually monitors each beat of the heart, but records only if it detects something abnormal.
- Depending on each patient’s needs, we set up various parameters; the monitor automatically records different types of arrhythmia, a fast heart rate, a slow heart rate, or atrial fibrillation (for which it uses a specific algorithm).
- Alternatively, if patients experience any symptoms, they have a remote control which they can put it in front of the device and press a button to “force” a recording.
How does monitoring work?
The ILR monitors the heart rate and rhythm continuously, day and night. If the heart rate or rhythm are outside the set parameters, the ILR automatically starts recording to the internal memory. It records the electrograms (single lead ECGs) of the events and the duration of the arrhythmias.
How is the recorded data transmitted to the physician?
- The patient doesn’t need to do anything. Data is automatically recorded and transmitted, so patient involvement is close to zero.
- The entire system is wireless, and usually when patients go to bed at night, the monitor communicates with a transmitter, which must be close to the bedside.
- The transmitter sends the recorded data to our monitoring company, which provides services 24/7/365.
- As there are many patients with these types of devices in our practice, obviously we cannot evaluate everyday transmissions with no abnormalities. We evaluate and address transmissions that meet the criteria of special alerts we set up depending on each patient’s diagnosis and the reasons we implanted the recorder.
- For some conditions (for which we set the highest level of alert), when there is evidence of an arrhythmia, we are notified within 24-48 hours, and then patients or their physician are contacted to discuss the findings and the type of action required. However, this requires an excellent daily transmitter connection. If for any reason the arrhythmia is not detected during these alerts, each month we receive and evaluate a full listing of the events during that period.
- In other circumstances, we want to evaluate the burden of arrhythmia or the response of an arrhythmia to medication or ablation: how often do episodes occur, how long are the episodes, etc. In these cases, we evaluate the findings each month when we receive a full record of what happened during that entire period.
- If patients are experiencing any concerning symptoms, they can force a recording using their remote. Additionally, they can manually send an immediate transmission by pressing the button on the transmitter. If immediate evaluation of the transmission is needed, then a phone call must be placed to our office to alert us about the transmission.
Can patients with an implantable loop recorder travel?
- The transmitter can transmit from anywhere in the world, so we invite patients to take the transmitter with them and travel wherever they’d like.
- For trips of up to two or even three days, patients should be fine without the transmitter, but for longer trips, patients should always take the transmitter with them.
- If patients are planning not to take the transmitter with them and will miss more than 2 or 3 days’ transmissions, then we ask to call and notify us about this ahead of time; otherwise, depending on the reason why the ILR was implanted, they might receive a phone call from our company to check on them.
What is the difference between the monitor and the transmitter?
- The monitor (ILR) is the device implanted that monitors each beat of the heart and records the arrhythmias.
- The transmitter is the device that stays close to the bedside, connects with the ILR monitor at night and transmits the data recorded by the ILR.
When do we consider using an implantable loop recorder?
There are a number of reasons why we use the ILR:
- Unexplained syncope
- Cryptogenic (of unknown origin) stroke – we use the ILR to evaluate for any possible atrial fibrillation of which the patients are unaware (occult atrial fibrillation)
- This is important to know, because if there is atrial fibrillation detected, patients should be on a blood thinner, as blood thinners have been proven to reduce the risk of recurrent stroke in patients with atrial fibrillation
- All patients who suffered a stroke should not be put on a blood thinner automatically, as studies have proven that this can increase the risk for bleeding with no clear benefit
- Unexplained, rare palpitations that could not be documented with an external monitoring system
- Monitoring for the burden of arrhythmias and their response to treatment