By Nicholas Tullo, MD
Implantable cardiac monitors (ICMs), otherwise known as implantable loop recorders (ILRs), are small devices that are inserted under the skin to continuously monitor the heart rhythm. They are capable of automatically detecting abnormal rhythms like atrial fibrillation, tachycardia, and bradycardia or pauses, and are extremely valuable in diagnosing patients with infrequent symptoms like fainting spells or palpitations. Detecting atrial fibrillation in stroke victims is extremely important since that means the patient is at higher risk of recurrent stroke and should be treated with blood thinners (anticoagulants). A new model ICM is now available that simplifies the patient’s ability to manage their own care, since it allows the use of a “smartphone” to monitor symptoms and to transmit abnormal rhythms quickly and easily.
Implantable cardiac monitors have been around for many years. The original device, the Reveal® (Medtronic, Inc, Minneapolis, MN), was a little larger than a pack of gum and required minor surgery to implant. The Reveal was updated several times but remained relatively large until 2015, when it was replaced by the “LINQ®” device. The LINQ was the first miniaturized ILR that could be inserted with a minimally invasive procedure that could even be done in a doctor’s office. It’s about the size of a paper clip and has a battery life of three years. The Medtronic LINQ system utilizes a pocket-sized “patient activator.” When the patient has a symptom, they use the patient activator, which sends a signal to the recorder through the skin, triggering the device to save a picture of the heart rhythm. This allows the patient to record the arrhythmia that is causing their symptoms. The device will also record abnormal rhythms automatically. The system comes with a receiving station that is plugged in to the wall socket next to the patient’s bed. Every night the LINQ wirelessly transmits a status report to the receiving station (which contains a cellular device). The report is then forwarded to Medtronic, and can be reviewed by the doctor online. This transmitted report would include any abnormal rhythms that occurred in the last 24 hours. Patients are also able to use that receiving station to manually transmit any symptom-related recordings the patient may have captured earlier in the day.
The new device, known as Confirm Rx® (Abbott/St. Jude Medical, St. Paul, MN), was recently approved by the FDA and is now available for use. This device communicates directly with your smartphone using Bluetooth wireless technology. This means that the patient is able to start a recording using an app on his/her phone and transmit that recording directly from the phone to St. Jude’s remote servers (which their doctor can access over the internet). Thus, there is no need for a patient activator or a separate receiving station. The Confirm Rx is about the same size as the LINQ and has a battery life of two years. The ability to use a smartphone to control the recorder allows for patients to be more engaged with their care and also avoids the need for separate, cumbersome devices to use the system properly. The device will also transmit automatically recorded rhythm disturbances through the smartphone without the need for the patient to return home to the receiving station.
If you have symptoms that occur infrequently or if you have had a stroke, your doctor may recommend an implantable cardiac monitor. Now there is a choice of devices to implant, and if you are comfortable using a smartphone, the Confirm Rx device might be the right monitor for you.