Inadvertent triggering of supraventricular tachycardia during pacemaker interrogation: Time to lose the magnet?

Abstract

A 22-year-old male had a dual chamber permanent pacemaker (PPM) implanted for complete heart block following aortic valve replacement for Shone’s syndrome 3 months previously. He presented with acute shortness of breath due to severe para-valvular leak with aortic valve dehiscence following a motor vehicle accident. He was scheduled for redo sternotomy and a pre-operative PPM check was undertaken. A programmer wand (Model 2067, Medtronic Inc., Minneapolis, MN, USA) was applied to the patient's PPM site to perform interrogation. During initialization, asynchronous DOO pacing at the magnet rate of 85 bpm was initiated with evidence of both atrial and ventricular capture. Competition from intrinsic rhythm resulted in functional loss of capture. Competitive pacing initiated a narrow complex supraventricular tachycardia at 180 bpm. The tachycardia persisted to result in clinical deterioration until reversion with urgent intravenous metoprolol. Programmer wands from Medtronic (Model 2067 & Encore) and Biotronik (Renamic, Biotronik Inc., Berlin, Germany) have in-built magnets that can cause asynchronous pacing during initialization of interrogation. Removing the magnet in future iterations of PPM programmer wands will mitigate inadvertent arrhythmia induction.

<Learning objective: Some pacemaker programmer wands contain in-built magnets that can initiate asynchronous pacing when placed over a cardiac implantable electronic device. This could result in asynchronous pacing and inadvertent triggering of arrhythmia. This risk can be minimized by placing the wand after the programmer is booted up to reduce the duration of asynchronous pacing. Device manufacturers should consider redesigning their products to make magnets redundant in future models of programming wands.>

Introduction

The number of patients with cardiac implantable electronic devices (CIEDs) is on the rise due to expanding indications for device implants and aging populations. Programming of CIEDs with device manufacturer specific programmer is often required outside of routine device follow-ups such as in the peri-operative setting whereby healthcare providers’ familiarity level with different device manufacturer specific programmers may vary greatly.

Case report

A 22-year-old male had a dual chamber permanent pacemaker (PPM; Azure XT, Medtronic Inc., Minneapolis, MN, USA) implanted for complete heart block following aortic valve replacement for Shone’s syndrome 3 months previously. He presented with acute shortness of breath due to severe para-valvular leak with aortic valve dehiscence following a motor vehicle accident. He was scheduled for redo sternotomy and a pre-operative PPM check was undertaken with a programmer wand (Model 2090, Medtronic Inc.) applied to the patient's PPM site.

During initialization, asynchronous DOO pacing at the magnet rate of 85 bpm was initiated with evidence of both atrial and ventricular capture. Competition from intrinsic sinus rate of 93 bpm resulted in functional loss of capture. Competitive pacing initiated a narrow complex supraventricular tachycardia (SVT) at 180 bpm (see telemetry rhythm monitoring in Fig. 1). The SVT persisted to result in clinical deterioration until reversion with urgent intravenous metoprolol. Subsequent device check showed normal function but no intracardiac electrogram of the SVT was stored by the PPM as the tachycardia detection rate was set at 200 bpm. His complete heart block had recovered a month previously with no ventricular pacing requirement. Notably, this patient had presented to another institution with spontaneous sustained short RP tachycardia that resolved with Valsalva maneuver previously.

Fig. 1.

This telemetry rhythm strip shows initial intrinsic sinus rhythm at 93 bpm. Asynchronous DOO pacing begun after placement of pacemaker programmer head. There was competition from intrinsic rhythm with functional loss of capture before initiation of a narrow complex tachycardia at 180 bpm.

Discussion

There is an increasing number of patients with CIEDs. All CIEDs contain magnet-sensitive switches that will respond to clinical magnet placement with activation of asynchronous pacing mode in PPMs and suspension of anti-tachycardia therapies in most implantable cardioverter-defibrillators without affecting pacing mode. Interrogation of CIEDs is recommended when necessary information to guide prescription of device management in the peri-operative period is unavailable or when the system is implanted within the previous 3 months [1]. The communication between programmer wands and CIEDs is generally via radiofrequency waves, with some manufacturers utilizing low energy Bluetooth in their latest generation devices. In some devices, magnetic coupling or continuous magnetic field is required to allow programming changes. Currently, programmer wands from two of the five CIED manufacturers, Medtronic (Model 2090 & Encore) and Biotronik (Renamic, Biotronik Inc, Berlin, Germany), still house an in-built magnet to facilitate interrogation and programming. This can result in asynchronous pacing during initialization of interrogation and potential undesired consequence of SVT induction as seen in our patient [2]. This may not be apparent to some healthcare providers who do not perform regular CIEDs checks.

While the latest generation Medtronic devices can be interrogated without magnet with the recently released CareLink SmartSync™ Device Manager due to utilization of Bluetooth technology, this system is currently unable to interrogate their previous generation non-Bluetooth devices that may require magnetic coupling to establish radiofrequency connectivity. Redesign of CIEDs’ circuitry with non-magnetic based switches will allow device manufacturers to remove the magnet in future iterations of PPM programmer wands, which will mitigate inadvertent arrhythmia induction. Clinicians can minimize asynchronous pacing and its potential harm by placing wand with in-built magnet over the patient’s device only after the programmer is fully booted up and ready for interrogation.

Conflicts of interests

Dr Linz reports having served on the advisory board of LivaNova and Medtronic. Dr Linz reports the University of Adelaide (UoA) has received on his behalf lecture and/or consulting fees from LivaNova, Medtronic, and ResMed. Dr Linz reports the UoA has received on his behalf research funding from Sanofi, ResMed, and Medtronic. Dr Wong reports the UoA has received on his behalf lecture, travel and /or research funding from Novartis, Servier, Boehringer Ingelheim, and Medtronic. Dr Sanders reports having served on the advisory board of Biosense-Webster, Medtronic, Abbott Medical, Boston Scientific, and CathRx. Dr Sanders reports that the UoA has received on his behalf lecture and/or consulting fees from Biosense-Webster, Medtronic, Abbott Medical, and Boston Scientific. Dr Sanders reports that the UoA has received on his behalf research funding from Medtronic, Abbott Medical, Boston Scientific, Biotronik, and Microport. Dr Lau reports that the UoA has received on his behalf lecture and/or consulting fees from Abbott Medical, Bayer, Biotronik, Boehringer Ingelheim, Medtronic, Microport, and Pfizer.