"A novel leadless pacemaker dislodged from a patient’s heart chamber and required a complex, two-snare retrieval, underscoring the evolving landscape of cardiac device technology and the critical need for sophisticated extraction techniques."
This incident, detailed in a recent case report, sheds light on a rare but significant complication associated with the latest generation of leadless pacemakers. While these miniaturized devices offer substantial advantages over traditional pacemakers by eliminating external wires and components, their internal placement necessitates meticulous surgical skill for both implantation and, in rare instances, removal. The case highlights the ingenuity of medical professionals in overcoming unforeseen challenges and emphasizes the ongoing importance of patient monitoring and prompt medical attention for any adverse symptoms.
A 64-year-old man, diagnosed with tachycardia-bradycardia syndrome—a condition characterized by alternating episodes of abnormally fast and slow heart rhythms—faced a critical cardiac issue. His medical history was further complicated by paroxysmal atrial fibrillation and end-stage renal disease, necessitating over three decades of hemodialysis. To manage his rhythm disorder and prevent fainting spells, he received a dual-chamber leadless pacemaker system, Abbott’s AVEIR DR, approved by the U.S. Food and Drug Administration (FDA) in July 2023. This advanced system, hailed as the world’s first dual-chamber leadless pacemaker, consists of two separate devices: one implanted in the right atrium and the other in the right ventricle. These units are designed to coordinate their pacing signals by transmitting them through the bloodstream, offering a wire-free solution for patients requiring pacing in both upper and lower heart chambers.
The AVEIR DR devices, described by Abbott as being "shorter, smaller and slimmer than a AAA battery," are anchored to the heart wall using a screw-like helix, a feature intended to facilitate future retrieval if necessary. However, in this particular patient’s case, the initial atrial device experienced a rapid decline in performance. Approximately two and a half years after its implantation, its battery depleted prematurely, and the energy required for pacing began to escalate. This necessitated the implantation of a replacement atrial device. Unfortunately, the new device exhibited poor electrical readings from the outset. Within a week of implantation, follow-up imaging revealed a startling complication: the leadless pacemaker had dislodged, flipped upside down, and migrated into the patient’s right ventricle. An electrocardiogram confirmed a complete loss of atrial pacing, with the heart now being paced solely from the ventricle.
The cardiologists at National Taiwan University Hospital in Taipei, who documented this case in JACC: Case Reports, theorize that the patient’s long-standing kidney failure may have contributed to the dislodgement. They propose a condition known as uremic atrial myopathy, where the chronic effects of kidney disease could have compromised the structural integrity of the atrial tissue, making it more challenging for the pacemaker’s anchoring helix to achieve a secure fixation. While this remains a hypothesis, it underscores a potential vulnerability in patients with severe chronic comorbidities.
The retrieval of the dislodged leadless pacemaker presented a significant clinical challenge. Traditional pacemakers, with their external leads, are typically removed by carefully pulling the wires. However, leadless devices, embedded within the heart muscle, require specialized techniques. The medical team initially attempted to extract the device using a single, three-loop snare catheter, a tool designed to grasp and retract foreign objects. While the snare successfully latched onto the device’s docking button, the pacemaker was firmly embedded, and it slipped free from the snare as the team attempted to withdraw it, retracting back into its protective sheath.
Recognizing the need for a more robust approach, the clinicians ingeniously employed a second, single-loop snare. This second snare was used to stabilize the dislodged pacemaker, providing a firm anchor. With the device held steady, the first snare was able to re-engage the docking button with sufficient grip, allowing for the safe extraction of the pacemaker under fluoroscopic (X-ray) guidance. This "double-snare" technique, while not entirely novel in the field of retrieving dislodged cardiac devices, demonstrated its efficacy in a complex leadless pacemaker scenario. Previous reports have documented the use of dual snares for retrieving different types of leadless pacemakers that have migrated to unusual locations, including the pulmonary artery and even the left side of the heart, with one instance involving an atrial device ending up in a kidney vein.
Following the successful retrieval, the focus shifted to reimplanting a new atrial leadless pacemaker. To mitigate the risk of repeat dislodgement, the team opted for a more precise implantation strategy. Instead of relying on trial-and-error, they performed a detailed 3D electroanatomic mapping of the right atrium. This advanced imaging technique creates a precise, real-time map of the heart chamber’s electrical activity, enabling physicians to identify areas of optimal tissue quality and electrical conductivity for device fixation. The goal of this mapping was to minimize repeated manipulation of the delicate heart tissue.
The new atrial leadless pacemaker was subsequently implanted near the base of the right atrial appendage, a location identified through the mapping process. This time, the device secured successfully on the first attempt, with a follow-up X-ray confirming its stable position. Four months post-implantation, the device demonstrated significantly improved performance, with a pacing threshold of 0.5 volts, a stark contrast to the 4.25 volts required by the device that had dislodged. This indicates a much more efficient and secure electrical connection.
Dislodgement, though a rare complication, is a recognized risk associated with leadless pacemakers. Current data suggests dislodgement rates of approximately 0.88% for ventricular leadless pacemakers and around 1.7% for their atrial counterparts. The AVEIR DR clinical trial itself reported five instances of atrial device dislodgement within the first 40 days after implantation, according to a 2024 case report.
The authors of this case report conclude that the double-snare retrieval technique is a safe and effective method for managing inverted atrial leadless pacemakers. Furthermore, they suggest that pre-implantation electroanatomic mapping could play a crucial role in reducing the incidence of fixation failure. However, it is important to acknowledge that this report is based on a single patient, and further research is needed to definitively establish the optimal retrieval and reimplantation strategies.
The vast majority of leadless pacemakers remain securely in place after implantation. Routine follow-up appointments with healthcare providers are designed to detect any potential issues early on. Patients who have received a pacemaker, regardless of type, should remain vigilant for any new or worsening symptoms. These may include new-onset dizziness, fainting spells, shortness of breath, or palpitations. Promptly contacting their care team if such symptoms arise is crucial for ensuring continued optimal cardiac function and overall well-being. The continuous evolution of leadless pacemaker technology, coupled with advancements in retrieval and implantation techniques, offers a promising future for patients requiring cardiac rhythm management, balancing innovation with robust patient safety protocols.
