Practical Guide to Optimizing Remote Monitoring Functions
Sylvain Ploux
KEY POINTS
Remote monitoring (RM) receives a Class I level A of recommendation for the follow-up of patients with cardiac implantable electronic devices. However, all RM systems are not equal.
Cardiologists should be aware of the advantages and limitations of the different systems in order to:
Best adapt the material to the patient profile
Ensure actual RM (maximal adherence)
Adapt their transmitted data management to the system specificities
RM should not be restricted to alerts collection. It should comprise periodical reports, in-depth analysis, and regular checks for nontransmitting patients.
INTRODUCTION
Two decades after Biotronik launched the first pacemaker with wireless transmission capabilities, remote monitoring (RM) has become the new standard of patient care with all kinds of cardiac implantable electronic devices (CIEDs), with alert-driven in-person evaluation replacing most routine office interrogations.1 CIED manufacturers have developed parallel proprietary RM solutions. Although the different systems share a common principle, they differ significantly in philosophy and practical application.2 Physicians in charge of a RM program should be aware of the capabilities and limitations of the different systems in order to best adapt the surveillance to the patient’s condition and to avoid loss of information and time. The purpose of this review is to present the main features of each RM system and highlight the specifics that matter in clinical practice.
RM TECHNOLOGY
Nowadays fully automated systems using either wireless or landline transmission technologies are considered as gold standard to operate CIED RM. Historical patient-initiated systems tend to be abandoned for safety and power saving reasons; therefore, they will not be addressed in the present review.3
RM monitoring of CIEDs comprises remote systematic interrogations with continuous surveillance of a limited (and variable) amount of device functions and clinical events (which may trigger “alert” transmissions). Usually the implanted device communicates with a transceiver every night, although Biotronik and Medtronic implantable cardioverter defibrillators (ICDs) allow real-time transmission for critical alerts when the patient is close enough to the transceiver.
Remote Periodical Interrogations
Remote periodical interrogations of nearly all the device content (with the exception of the Biotronik electrogram [EGM] tracings) can be scheduled remotely from the website manufacturer. Additional patient-initiated interrogations are possible, except with the Biotronik system.
Alerts choice
The alerts can be individually programmed via the website for Biotronik, Boston Scientific, and Abbott devices, but solely on the programmer for Microport and Medtronic devices. The possibility to remotely control the alerts and their boundaries avoids message redundancy and unwanted clinic visits. The number of alerts varies considerably from one system to another.
Alert Recurrence Policy
The number of alerts per category between two programmer interrogations may be limited depending on the alert recurrence policy of the RM system. These major differences have direct consequences on the alert management and the frequency of in-person evaluation. For example, after a first alert for shock delivery, CareLink will not alert for the same condition unless the device has been interrogated with a programmer (Figure 5.1).
The Abbott system does not limit the number of alerts between two programmer interrogations.
The Biotronik ICD’s system does not limit the number of alerts between two programmer interrogations. To be retriggered, the alert condition must be terminated and acknowledged on the website, otherwise the system will send periodical recalls. For pacemakers, high atrial and ventricular rate episodes are limited to 5 transmissions and leads problems to 2 transmissions between two in person interrogation.
The Boston Scientific system sends only one notification for each technical alert condition detected by the system. It does not repeat alert notifications unless the condition is reset with a programmer. There are however no restrictions for the clinical alerts. The “Right ventricular non-physiologic signal detected” and “Lead impedance abrupt change” alerts can be retriggered as well.
The Microport RM system sends a maximum of two alerts for each category between two programmer interrogations, except for shock/antitachycardia pacing (ATP) delivery, which can be sent up to 8 times.
The Medtronic system does not retransmit a wireless alert notification that has already been successfully transmitted, until the alert is cleared by programmer interrogation.
EGM Transmission Policy
Abbott, Boston Scientific, Microport, and Medtronic behave similarly. Every arrhythmia alert is accompanied by (at least) one EGM of the episode(s). These systems transmit the entire device library with unaltered EGMs. In addition, each
transmission generates a “real-time EGM” acquired at the time of the transmission. Biotronik sends a limited number of truncated EGMs per session (four per session for ICDs, one per session for pacemakers) unless the episode occurs at the vicinity of the home monitoring transceiver (direct transmission of the current episode, for ICDs only). Biotronik EGMs are triggered not only by arrhythmia episodes but also
by technical issues (impedance out of range, threshold test failed, right ventricular [RV] sense amplitude out of range, RV lead monitoring, etc.). These technical EGMs carry additional value for recognizing device malfunction. Finally, periodical EGM can be remotely scheduled and requested with a 3/5-day delay.
transmission generates a “real-time EGM” acquired at the time of the transmission. Biotronik sends a limited number of truncated EGMs per session (four per session for ICDs, one per session for pacemakers) unless the episode occurs at the vicinity of the home monitoring transceiver (direct transmission of the current episode, for ICDs only). Biotronik EGMs are triggered not only by arrhythmia episodes but also
by technical issues (impedance out of range, threshold test failed, right ventricular [RV] sense amplitude out of range, RV lead monitoring, etc.). These technical EGMs carry additional value for recognizing device malfunction. Finally, periodical EGM can be remotely scheduled and requested with a 3/5-day delay.
 FIGURE 5.1 CareLink transmission summary from a Medtronic Evera MRI XT DR showing a first CareAlert-driven transmission on September 10, 2016, followed by two scheduled (November 7 and February 6, 2017) and one patient-initiated (January 9, 2017) transmissions with no intermediate CareAlert notification despite the presence of CareAlert conditions. On September 10, 2016, three CareAlerts were notified: one Shock Delivered for an Episode (true fast ventricular tachycardia), atrial tachycardia (AT)/atrial fibrillation (AF) Daily Burden greater than Threshold, and Fast V Rate during AT/AF. As long as the device has not been interrogated with a programmer, CareLink is not able to notify these alerts again. As a result, the inappropriate shock delivered on January 17, 2017 was discovered 20 days after on the quarterly scheduled report (June 2, 2017). |
Pacemaker RM
Abbott, Biotronik, and Boston Scientific pacemakers can be remotely followed using the same technologies and modalities as ICDs. Since 2018, Medtronic pacemakers can be followed by means of the patient’s smartphone. Until now, Microport pacemakers could only benefit from remote inductive interrogations (wand-based radiofrequency platform).
Implantable Loop Recorder RM
The Abbott Confirm Rx implantable loop recorder (ILR) provides automatic transmission of all the device content using the patient’s smartphone.
The Biotronik Biomonitor II ILR provides automatic transmission every night using the common Biotronik transceiver with up to six episodes per day.
The Medtronic Reveal DX ILR can be periodically remotely interrogated using an inductive system. In addition, the Medtronic Reveal Link provides basic wireless transmission with the possibility to transmit the latest episode of the highest priority. This communication is unidirectional (device to monitor only) and repeated for 14 days unless an episode of equal or higher priority occurs. Only 10 seconds of an atrial fibrillation (AF) episode can be automatically sent on this model; AF always has the lowest level of priority. With the LINQ TruRhythm, 30 seconds EGM can be transmitted for an AF episode.
Table 5.1 summarizes the main technical features of each RM system.
Optimization Advice
The remote periodical interrogation calendar should be determined according to the alert notification policy of the system. Consider closer remote interrogations (<3 months) when using a limited number of alerts in order to decrease time before a medical decision. Periodical reports must be explored in detail, with particular attention paid to the lead function trends and the transmitted EGM.4
Patient-initiated transmissions must be either motivated by symptoms or performed at the request of the RM team, in order to spare battery life and avoid data overload. This must be part of the patient’s education.
The alert settings can be customized for each patient. However, a clinic alert grouping is usually more convenient at RM initiation. Biotronik allows the creation of different alert templates.
Automatic wireless RM systems should be preferred to inductive systems. The use of mobile transceivers (including smartphones) favors traveling and increases patient adherence to RM.
ICD LEAD-RELATED ALERTS
The ICD performance relies on the defibrillation lead integrity. ICD lead dysfunction may result in adverse clinical consequences such as failure to deliver therapy, inappropriate therapies, or loss of bradycardia pacing. The ICD lead surveillance encompasses different aspects:
Lead impedance monitoring. In its simplest form, lead impedance monitoring consists of triggering an alert for each impedance out of the lower or upper boundary (which can be remotely changed through the Biotronik website). Contemporary
Biotronik ICDs provide EGMs acquired at the time of “out of the range” RV or shock impedance measurement. Optionally, the Boston Scientific system can be configured to send an alert for lead impedance variations. The Medtronic Lead Integrity Alert is also sensitive to impedance changes. Alternatively, a visual inspection of the lead trends may reveal suspicious impedance changes (Abbott, Biotronik, and Microport).
TABLE 5.1 Fully Automated Remote Monitoring Technologies
Transceiver
Abbott
Biotronik
Boston Scientific
Microport
Medtronic
Name
Merlin.net
Biotronik Home Monitoring
Latitude NXT
Smartview
CareLink
ICD
PM
ILR
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
[check mark]
Cellular
Landline
Internet
3G
GPRS/3G
3G
GPRS
GPRS/3G
[check mark]
United States only
[check mark]
[check mark]
[check mark]
[check mark]
United States only
Scheduled interrogation
1 wk-1 y
Daily
1 wk-1 y
1 d-1 y
1 wk-1 y
Direct transmission
[check mark]
[check mark]
Transmitted EGM/session
All
4 ICD/1 PM
All
All
All
Remote control of the alerts
[check mark]
[check mark]
[check mark]
[check mark]
Remote setting of the alerts
[check mark]
[check mark]
Patient-initiated transmission
[check mark]
[check mark]
[check mark]
[check mark]
Direct transmission: ability to transmit a critical alert anytime—when the patient is close enough to the transceiver (ICDs only).
Scheduled follow-up:
1 wk-1 y: programmable from weekly to yearly.
1 d-1 y: programmable from daily to yearly.
Transmitted EGM/session: For Biotronik ICDs: up to four EGMs can be transmitted per session, unless the episode occurs in the vicinity of the transmitter (direct transmission). For pacemakers, only one episode can be sent, there is no direct transmission.
“All” referred to all memorized EGM that have not already been sent.
Remote control of the alerts: ability to switch on/off an alert remotely through the website. Some alerts remain accessible only through the use of a programmer.
Remote setting of the alerts: ability to remotely change the boundaries of an alert. For example, the Biotronik system allows changes in the lower and upper limits for lead impedance.
Abbreviations: EGM, electrogram; ICD, implantable cardioverter defibrillator; ILR, implantable loop recorder; PM, pacemaker. Adapted from Ploux S, Varma N, Strik M, Lazarus A, Bordachar P. Optimizing implantable cardioverter-defibrillator remote monitoring: a practical guide. JACC Clin Electrophysiol. 2017;3(4):315-328.
R wave amplitude monitoring. A drop in the R wave amplitude may manifest as lead failure, lead dislodgement, oversensing, or an electrode-myocardial interface
change. Biotronik and Boston systems only provide dedicated alerts for RV intrinsic amplitude out of range, respectively less than 2 mV and less than or equal to 3 mV (Biotronik sends the corresponding EGM). For the other three systems, a careful inspection of the R wave amplitude trend is required.
RV threshold monitoring. An abrupt rise of the pacing threshold is compatible with a lead failure and a RV lead dislodgment and may compromise pacing support. Biotronik and Boston Scientific systems only provide dedicated alerts for RV threshold above a limit. For the other three systems, a careful inspection of the RV threshold trend is required.
Noise detection. Noise oversensing is the most common presentation of ICD lead fracture.5 Various algorithms have been designed to alert the presence of repetitive nonsustained rapid ventricular rhythms. Biotronik uses a short RR interval counter, Boston Scientific tracks short RR intervals within ventricular arrhythmia-detected episodes, whereas Microport sends an alert for accumulation of nonsustained ventricular fibrillation (VF) episodes. The more sophisticated Medtronic Lead Integrity Alert algorithm is triggered either by impedance changes or by rapid oversensing.6
Noise discrimination. Abbott and Medtronic provide noise discrimination algorithms that differentiate ICD lead noise from ventricular arrhythmias by comparing a far-field EGM signal to near-field sensing. Once a lead noise is identified, these algorithms are designed to withhold therapies and trigger an alert.7
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