"ILRs- Implantable Loop Recorders, Insertion Guidance and After Care Precautions- A Review and Reflection of the Literature and Our Experience"

In the cardiology and electrophysiology clinic there are several
diagnoses which challenge the provider to determine the specific
arrhythmia...

a preset length of time determined by the device's internal battery life with the average LINQ battery life estimated at three years [6], Indications for loop recorders include syncope, cryptogenic stroke to assess for atrial fibrillation, palpitations and resultant symptoms, and a need to gain an overall atrial fibrillation burden [7]. The ILR devices provide ongoing monitoring and can capture any arrhythmia over several years. They function in a retrospective fashion and give the provider a mirror of trends in arrhythmia or unusual changes in the heart rhythm. Coupled with a careful journal of patient complaints, they provide vital information from which the provider makes the diagnosis and treatment plan. Indications for ILR devices are outlined by the Heart Rhythm Society. If an indication for an ILR implant is verified one can then plan and expedite the ILR implant procedure.

FDA Approval for Small-Implanted Loop Recorders
The process of monitoring one's arrhythmias became much easier in February 2014 with the release of the LINQ monitor from the Medtronic ™ corporation, the smallest monitoring device available. This device is a subcutaneously placed monitor which is one third the size of a triple A battery, 1.2 cc and transmits data via remote monitoring [6]. It then quickly became an easy way to determine abnormal arrhythmias and possible causes of strokes, which may have eluded periodic external monitoring techniques in the past [8]. The following is an overview of the use of the LINQ monitor, expected outcomes, unusual ILR complications and trouble-shooting tips for the provider.

Evolvement of Procedure Room; Holding Room Insertions of ILRs
With the introduction of the Medtronic LINQ ILR and its lowprofile size, weight, and subcutaneous injection delivery system came great excitement for such an easy delivery system of such an advanced device. Many facilities started performing the insertion of the ILRs in other treatment areas, rather than the cardiac catheterization labs and electrophysiology labs. The ease of the insertion of the device led to these devices being implanted with advanced professional staff such as physician assistants and nurse practitioners in procedure rooms and holding bays. Following this change in practice from a conventional lab setting, there were several studies to analyze potential side effects and the efficacy of this new practice. Four studies in particular show a low likelihood for adverse events and review some learned pearls of knowledge for the insertion and care of these devices. The four cases involving LINQ studies and studies of in office, holding room, procedure room and advance practice profession placement of the devices are outlined in the literature review. In our practice of a 1000 bed tertiary care facility and EP lab   which implants approximately 250 loop recorder devices per year [9], we have a very low side effect profile, much as is seen nationally. As in previous loop recorder studies [10] our side effect profile includes localized bleeding (small hematoma), localized skin changes (irritation and or rash) and localized infection or mild pain at the insertion pocket site [11]. These side effects are limited to a less than1-2% chance of occurrence and are easily managed with short term compression, skin care and acetaminophen or ibuprofen. Of note, we are particularly interested in 4-5 scenarios which have presented in the last 3-4 years with patients complaining of recurrent and very intense pain at the device site requiring prescribed narcotic medications, ice and compression of the area, and in two cases, removal of the loop recorder. Of note, two of the instances include devices which were placed at outside hospitals and our service simply saw the patient due to change in living locations or transferring from another region of the country.

Typical Implanted Loop Recorder Practices
We first reviewed our typical placement of loop recorders and the precautions we take with every placement of an internal cardiac monitoring device. In analyzing possible pain or unusual cases Five milliliters of local anesthesia (as above) is injected into the subcutaneous space. An incision is then made utilizing the angled blade provided in the LINQ-tm insertion kit. The monitoring device is inserted into the subcutaneous space parallel to the skin utilizing the insertion tool. The tool is then turned 180 degrees to create the pocket. While firmly holding the insertion tool against the skin, the device is injected into the subcutaneous tissue parallel to the skin. The device is interrogated to assure proper sensing. The device is programed based upon the diagnosis. Pressure is then held for 5 minutes to ensure hemostasis [6]. Glue is applied to the skin, followed by steri-strips and a telfa pad [6,12]. Some of our physicians prescribe antibiotics prior to the procedure and some do not, depending upon personal preference ( Figure 1).

Picture from Medtronic Advertising Site
After completion of the procedure care includes removing the dressing in 48 hours. Leave the steri-strips in place until they start to peel off. Patient education is completed in the recovery area prior to patient being discharged from the area. A wound check is scheduled and maintained in 7-10 days.

Literature Review
This literature review examined advantages of an ILR, evolving ILR technology, possible skin changes or rashes, increased pain at the insertion site, migration of the loop recorder and dislodgement of the loop recorder. This search proved to be challenging as the LINQ loop recorder insertion is associated with such a low complication rate and considered a smooth and relatively troublefree procedure [10]. The literature review revealed cases which included the term "pain" but did not directly relate to the pocket site pain. At our institution we have experienced 2-3 complaints which have experienced localized pain directly at the pocket insertion site. One article discussed a gentleman who initially experienced pocket site pain which improved but later developed chest and jaw pain. Such pain was initially felt to be anginal in nature and there was concern for an evolving ischemic cardiac event. He was evaluated for an acute coronary syndrome with a negative stress test. Within a day he was referred for an outpatient chest x-ray and was ultimately found to have a migrating loop recorder which was seen in the lower abdomen. The LINQ device was removed with an open surgical procedure [13].
There was an additional case of the LINQ migration involving a 78 year-old gentleman who had a LINQ loop recorder inserted with mild pain at the insertion site after the initial implant. The pain at the site slowly improved, but the patient developed pleuritic chest pain 35 days post ILR placement. The ILR had migrated to the left pleural space and was identified in this pleural space region on a computed tomography study (CT). The ILR was then removed with a video assisted thoracoscopic procedure utilizing a port and with forceps [14]. The final example of a LINQ loop recorder and pain is noted by Pocoro [15].  The final study also published in 2017 described low risk complication rates in the LINQ insertion within an electrophysiology lab as well as an outpatient procedure room within the LOOP study [21]. There were 1420 patients in the study and post implant pain was noted in 3 patients and an additional post implant pain complaint which resulted in the implant extraction. There was also noted minor bleeding or hematoma in 4 instances, superficial infection noted with 13 patients, and pocket erosion noted with 3 patients. There were a total of 18 devices which were removed and 9 of them were for pocket erosion, pain or infection and 9 were due to patient request with no physical abnormality [21].
Of interesting note, the patients with the higher body mass index (BMI) experienced more complications (which we have also observed within our practice and described to follow). The conclusion of the study is that the LINQ insertion is a very low risk procedure They noted a higher risk for those patients requiring repositioning of the device with a higher associated infection rate in those patients requiring repositioning outside of the conventional sterile electrophysiology laboratory setting [21]. The conclusion warns caregivers to be aware of the extra need for caution with patients with repositioning needs of the LINQ placed at the outside of the EP setting and a higher complication rate in either setting with those patients with a higher BMI [21].

Our Typical Procedure Practice
In implanting the ILR devices our facility has taken several precautions to ensure minimal risk and assure prompt healing from this minimally invasive procedure. ILRs are implanted in a sterile environment and using surgical sterile techniques. Care is given to insert the device subcutaneously, avoiding deep insertion with muscle or fat tissues. From our facility's practice we have experienced one event with a patient with morbid obesity in which the loop recorder was initially bothersome to the patient and ultimately needed forceps retrieval. Post procedural instructions are given to keep area clean and dry for the first one week.

Picture of ILR tracing
Tracing via Medtronic education site (Figure 3).

Complaints of Pain at the Device Site, Without Physical Findings
Our service has experienced complaints from patients who had the device inserted at outside facilities and transferred care to our service. We have also received complaints from patients who had the device inserted at our facility with no obvious cause of the complaint. The complaint which is most common is one of pain at the insertion site out of proportion to any physical findings.
The exam has shown to be normal in these cases and involves no redness, no streaking and no discharge from the site. Our usual work up includes discussion of specific complaints to pinpoint related events, signs and symptoms or underlying conditions which may affect the device site healing and any abnormal outcomes.
Once the history and physical details are thoroughly discussed and examination will then be done. With the examination, often no offending findings are noted and there has been no erythema, rash, no swelling and no leakage.
We then move forward with a chest x-ray which often shows no culprit findings for the individual out of the anticipated level of pain for such a minor procedure. We often first recommend nonsteroidal anti-inflammatory medications such as ibuprofen. Our There have been a few cases in which we have noticed changes in our ECG tracings and suspected movement of the device. We have brought the patient in for a physical examination and have noted the pocket site is rather larger in comparison to the LINQ device.
We have then extracted and re-implanted out of the exact previous region, with very good success.
In our practice we have seen minimal LINQ ILR complications.
The reference cases have caused us to be cautious in not delivering the device too deeply into the subcutaneous fat. We remain diligent in delivering the device to the recommended 8 mm depth. We have been cautious to meet with patients in person and to directly assess skin changes for possible extrusion or local rejection of the device.
We continue to question cases of intense or prolonged pain with no local evidence of hematoma, no skin changes, and no radiographic evidence of migration. Some of these cases have resolved over several weeks with the use of analgesics and conservative local care

3.
Be aware that without physical findings or radiologic findings initially, that over time the device may migrate elsewhere or surface and extrude at the insertion site.

4.
Remember to fully investigate post-operative complaints thoroughly which may entail repeat follow-up visits over several weeks.

5.
Be cautious with the initial implants to follow the recommendations from Medtronic LINQ ILR package insert or other company recommendations and be cautious to avoid too shallow or too deep insertion of the ILR.