Lumbar medial branch radiofrequency neurotomy in a patient with a leadless pacemaker: a case report

Abstract

Introduction

Facet-mediated lumbar pain is commonly treated with radiofrequency neurotomy (RFN) following confirmatory medial branch blocks. Because RFN generates electrical current, concerns exist regarding electromagnetic interference (EMI) in patients with cardiac implantable electronic devices, particularly leadless pacemakers, for which limited procedural guidance is available.

Case report

We present the case of an 81-year-old man with chronic low back pain and a right ventricular leadless pacemaker (Medtronic Micra) who underwent lumbar RFN after successful diagnostic blocks. Pre-procedural electrophysiology evaluation confirmed he was not pacemaker dependent, and the device was interrogated without reprogramming. Bipolar lesioning was performed with continuous cardiac monitoring. The procedure was completed without complication, and post-procedural interrogation demonstrated normal device function. The patient reported significant pain relief at follow-up.

Discussion

This case highlights that lumbar RFN can be safely performed in patients with a leadless pacemaker when a multidisciplinary approach is utilized. Key considerations include confirmation of device type and pacemaker dependency, pre-procedural interrogation, use of bipolar lesioning to reduce EMI risk, and continuous peri-procedural monitoring. As leadless pacemakers become increasingly prevalent, further research is needed to guide specialty-specific recommendations for interventional pain procedures involving radiofrequency-based therapies.

1. Introduction

In the United States, chronic back pain persisting for more than one year has been reported in up to 60% of the population [1], with a lifetime prevalence approaching 80% [2]. Among these cases, approximately 15-45% are attributable to facet joint arthritis [1]. Management of this condition frequently involves radiofrequency neurotomy (RFN) [2] of the medial branches of the dorsal rami innervating the affected joints, following patient selection via diagnostic medial branch blocks (MBB) [3]. A meta-analysis of twelve randomized controlled trials evaluating RFN subsequent to diagnostic MBB demonstrated a reduction in low back pain at six-month follow-up in 80% of the studies [1]. Furthermore, a separate systematic review found that patients who achieved complete pain relief with MBB and underwent RFN using a parallel electrode placement technique experienced ≥50% improvement in back pain at six-month follow-up [4].

RFN involves placing a cannula near the medial branches and applying electrical current to produce coagulation [3]. The alternating current between the cannula tip and grounding pad generates heat, producing ablation [3]. While effective for pain control [2], it raises important safety concerns in patients with cardiac implantable electronic devices (CIEDs), as the electrical current may cause electromagnetic interference (EMI).

In patients with CIEDs, EMI may lead to inappropriate sensing, under-pacing, bradycardia, or device reset [5]. In more severe cases, EMI can precipitate ventricular tachyarrhythmias, cardiac arrest, or device malfunction [6]. More than one million pacemakers are implanted globally each year, including over 260,000 in the United States [7]. To reduce complications such as lead dislodgement, fracture, infection, and thrombosis, leadless pacemakers were introduced in 2016 as an alternative to traditional transvenous systems [7]. Although these devices decrease pocket-related complications, bleeding risk, and the aforementioned lead-related issues, limited clinical evidence exists to guide their management during RFN [8]. Traditional pacemakers can typically be placed into an asynchronous pacing mode or have therapies suspended through magnet application; however, certain leadless systems, such as the Medtronic Micra [9], do not respond to magnets [5] due to their position deep within myocardial tissue [9]. This distinction is clinically relevant, as current expert consensus recommends that leadless pacemakers be programmed pre-procedurally for high EMI risk procedures and that such procedures be performed with external pacing and defibrillation support available [9]. Post-procedural device interrogation is also advised to confirm appropriate device function and assess for potential adverse events [9].

Given that leadless systems are becoming increasingly common, understanding their management in interventional pain procedures is highly relevant. We present a case of lumbar RFN in a patient with a leadless pacemaker to contribute to this developing area of clinical practice. Written consent from the patient was obtained before publication of this report per our institutional policy.

2. Case report

An 81-year-old male with a past medical history of chronic kidney disease stage 3, coronary artery disease status post stent placement, atrial fibrillation status post ablation, hypertension, and diabetes presented to the pain medicine clinic with greater than 20 years of low back pain, exacerbated at time of presentation by a fall a few months prior.

The patient's symptomatology and physical exam were consistent with right sided facet arthropathy. The patient underwent two sets of diagnostic right sided lumbar MBBs with near complete, transient pain relief after each set. The patient subsequently underwent thermal RFN of the right L3 and L4 medial branches and the L5 dorsal ramus with near complete relief of pain for over 6 months. Afterwards, he underwent repeated right side lumbar RFN with similar results. He then developed left sided axial low back pain and was scheduled for diagnostic left sided lumbar MBBs. However, prior to the diagnostic blocks, he experienced syncope. He underwent a cardiac workup and was noted to have prolonged first degree atrioventricular (AV) block. He then underwent placement of a right ventricular leadless pacemaker (Medtronic Micra). The patient later underwent two sets of diagnostic left side lumbar MBBs with near complete, transient relief of pain after each set. Prior to proceeding to the left lumbar RFN, the patient saw the electrophysiology team. The patient was noted not to be pacemaker dependent. Electrophysiology interrogated the pacemaker wirelessly and did not alter its programmed mode. Risks and benefits were discussed with the patient who elected to proceed. Bipolar lesioning was used to decrease risk of EMI. Two twenty-gauge radiofrequency cannulas with 10 mm active tips were placed in close proximity to each medial branch. Two Hz stimulations were performed to rule out radicular stimulation up to 2 V. One cc of 2% lidocaine was injected at each nerve followed by RFN lesioning at 80 °C for 90 seconds at each level. The patient tolerated the procedure well without any complications. During and after the procedure, the patient was monitored with electrocardiogram, pulse oximetry and noninvasive blood pressure measurements. The patient sent a remote transmission from the pacemaker to the electrophysiology team. The leadless pacemaker was functioning normally and did not incur any damage or alteration of function during the ablative procedure. At follow-up, the patient reported an improvement in pain.

3. Discussion

The American Society of Anesthesiologists (ASA), the American Heart Association (AHA), and pain societies including the American Society of Pain and Neuroscience (ASPN) and International Pain and Spine Intervention Society (IPSIS) [10] have each published guidelines or advisories addressing the perioperative and periprocedural management of conventional CIEDs. Notably, the AHA guidelines are the only ones to address leadless CIEDs; however, they acknowledge that additional consensus and clinical evidence are needed [9]. Across these societies, recommendations consistently emphasize a comprehensive preoperative evaluation that includes identification of CIED type, indication for implantation, current programming, patient pacemaker dependency, recent interrogation data, and assessment of whether electromagnetic interference (EMI) is anticipated above or below the umbilicus [9,11,12]. When EMI-generating equipment is used below the umbilicus, no device reprogramming is typically recommended, provided that appropriate monitoring is maintained [12]. Conversely, when EMI is expected above the umbilicus in pacemaker-dependent patients or in those with an implantable cardioverter-defibrillator (ICD), consultation with the CIED team and pre-procedural reprogramming to an asynchronous mode is advised [12]. In all situations, continuous intraoperative and postoperative cardiac monitoring is recommended [9,11,12]. Postoperative interrogation is generally reserved for cases in which the device was reprogrammed, significant intraoperative events occurred, or there is concern for CIED malfunction [12].

Currently, only two leadless pacemakers are commercially available—the Medtronic Micra and the Abbott Aveir—both of which either do not respond to magnet application or exhibit unreliable magnet responsiveness [9]. This limitation underscores the importance of preoperative interrogation and, when indicated, preemptive CIED reprogramming [9]. The patient described in this case carried a Medtronic Micra, a miniaturized leadless pacemaker implanted directly into the right ventricular myocardium via a transcatheter approach [13]. The Micra provides only single-chamber ventricular pacing and does not offer atrioventricular synchrony, thereby reducing the risk of pacemaker syndrome [13]. It is capable of remote interrogation, rate-responsive pacing, and automated capture threshold management [13].

Manufacturer guidance for the Micra advises avoiding electrosurgery due to the risk of oversensing; however, when electrosurgery is unavoidable, the use of bipolar electrosurgery is recommended [13]. Electrosurgical units (ESUs) represent the most common source of EMI and may be operated in monopolar or bipolar modes [14]. Monopolar electrosurgery is significantly more likely to generate EMI than bipolar electrosurgery [14]. Furthermore, monopolar cautery above the umbilicus carries a greater EMI risk than procedures performed below it [15]. In a prospective cohort study, more than 20% of patients with a CIED experienced EMI when monopolar ESU was used above the umbilicus, whereas no EMI was observed when it was used below the umbilicus [7]. In patients who are partially pacemaker dependent, EMI may result in under sensing and precipitate an R-on-T phenomenon, in which a pacing stimulus falls on the T wave of the intrinsic cardiac cycle. This can lead to ventricular tachycardia and/or ventricular fibrillation, and cardiac arrest [6].

In our case, the patient's CIED underwent a detailed preoperative assessment, including confirmation of device type, indication, dependency status, magnet responsiveness, last interrogation, and programming. Because electrosurgery was anticipated above the umbilicus, the device was interrogated preoperatively. As the patient was not pacemaker dependent, no reprogramming was required. Bipolar cautery was employed intraoperatively to minimize EMI risk, and continuous cardiac monitoring was maintained throughout the intraoperative and postoperative periods. No complications or CIED dysfunction occurred.

Further research is warranted, particularly in pacemaker-dependent patients, to better clarify perioperative management strategies for leadless systems. Evidence within the pain medicine literature remains limited. In the anesthesiology literature, a case report described a pacemaker-dependent patient with a leadless device undergoing tricuspid valve replacement with monopolar electrosurgery above the umbilicus without any observed EMI or adverse events [15]. In that instance, the device was interrogated several hours before surgery, maintained in its programmed VVIR mode (a single chamber, sensed, rate-responsive mode–pacing and sensing the ventricle with an inhibited response to native heart beats and rate response to increased oxygen demand) [15], and the electrophysiology team remained available intraoperatively. The absence of EMI—despite the use of monopolar electrosurgery above the umbilicus—suggests that the intramyocardial placement of leadless pacemakers may confer some degree of intrinsic protection from EMI. The Anesthesia Critical Care Pain Medicine Journal, the Canadian Cardiovascular Society, and the Canadian Anesthesiologists’ Society recommend electrophysiology consultation and CIED reprogramming for pacemaker-dependent patients if risk of EMI is high, although this is not required [16,17].

Given the common use of radiofrequency ablation within pain medicine and an aging population, interventionalists will increasingly encounter patients with leadless CIEDs. Understanding the nuances of EMI risk and device-specific management is essential to safe practice. This case demonstrates that lumbar radiofrequency neurotomy can be performed safely in a patient with a leadless pacemaker when a multidisciplinary approach is employed, including electrophysiology consultation, confirmation of pacemaker dependency status, use of bipolar lesioning techniques, and appropriate peri-procedural monitoring. As radiofrequency-based therapies continue to expand within pain medicine, further research is needed to inform specialty-specific guidelines and optimize procedural safety in patients with evolving cardiac device technologies.