Leadless Cardiac Pacemaker Research Articles

Advanced helix-fixation leadless cardiac pacemaker implantation techniques to improve success and reduce complications.

Leadless cardiac pacemakers (LCPs) are becoming more commonly utilized because of their potential advantages (i.e., reduced short and long-term complications, improved patient comfort) and may be the preferred option for patients with venous access problems, high-risk for infection, previous lead fractures, or skin erosion. There are currently two types of LCP fixation mechanisms that have been FDA approved-Medtronic's Micra system has a tine-based fixation and Abbott's Aveir system has a helix-fixation design. This article highlights important tips and tricks for a successful implant of a helix-fixation LCP, particularly when difficulties are encountered, and provides precautions to avoid potential complications. Cases of single chamber Aveir LCP implantation were reviewed to highlight examples of procedural pitfalls and suggested methods to circumnavigate them. There are unique procedural considerations regarding the Aveir LCP implant as well as challenges that that may be occasionally encountered. Techniques to address these-such as avoiding air embolism, maneuvering difficult entry into the right ventricle, handling complicated positioning/repositioning, evaluating proper fixation, and releasing difficult tethers-are illustrated in detail. Advice to reduce risks of perforation and to position optimally for potential retrieval and communication for dual chamber pacing are also described. The advanced teaching concepts described and emphasized in this article may help improve success and prevent procedural complications, especially when physicians are learning how implant these novel helix-fixation LCPs.

(487) Use of Leadless Cardiac Pacemakers in Heart Transplant Recipients: A Case Series

(487) Use of Leadless Cardiac Pacemakers in Heart Transplant Recipients: A Case Series

Electromagnetic interference : Pacemakers, cardiac resynchronization therapy devices, implantable cardioverter-defibrillator

Patients with cardiac pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy devices (CRT) are exposed to different types of electromagnetic interference (EMI) at home and at work. Due to the constantly increasing role of electrically active appliances in daily use and the introduction of new therapy concepts such as the leadless cardiac pacemaker and the subcutaneous defibrillator, this topic is of great relevance. The further development of the implanted devices and the almost complete use of bipolar leads has reduced the overall risk of EMI. This review article provides information about the current status of possible interference in the private environment and how to avoid it. In addition, information is provided on how to deal with occupational sources of interference.

Modulation Scheme Analysis for Low-Power Leadless Pacemaker Synchronization Based on Conductive Intracardiac Communication.

Conductive intracardiac communication (CIC) has been demonstrated as a promising concept for the synchronization of multi-chamber leadless cardiac pacemakers (LLPMs). To meet the 2-5 μW power budget of a LLPM, highly specialized CIC-transceivers, which make optimal use of the cardiac communication channel, need to be developed. However, a detailed investigation of the optimal communication parameters for CIC-based LLPM synchronization is missing so far. This work analyzes the intracardiac communication performance of two low-power modulation techniques, namely On-Off-Keying (OOK) and Manchester-encoded baseband transmission (BB-MAN), as a function of the transmitted bit-energy. The bit error rate (BER) of a prototype dual-chamber LLPM was determined both in simulation and in-vitro experiments on porcine hearts. A BER of 1e -4 was achieved with a median bit-energy in the range of 3-16 pJ (interquartile range: 4-15 pJ) for data rates from 75-500 kbps and a receiver input noise density of 7 nV/ √{Hz}. Both modulation schemes showed comparable performance, with BB-MAN having a slight bit-energy advantage (1-2 dB at 150-500 kbps) under equalized transceiver characteristics. This study demonstrates that reliable CIC-based LLPM synchronization is feasible at transmitted power levels 10 nW under realistic channel conditions and receiver noise performance. Therefore, modulation techniques such, as BB-MAN or OOK, are preferable over recently proposed alternatives, such as pulse position modulation or conductive impulse signaling, since they can be realized with fewer hardware resources and smaller bandwidth requirements. Ultimately, a baseband communication approach might be favored over OOK, due to the more efficient cardiac signal transmission and reduced transceiver complexity.

A Triple Band Circularly Polarized Antenna for Leadless Cardiac Transcatheter Pacing System

The ground-breaking entry of leadless cardiac pacemakers in the cardiac pacemaker’s world has resulted in the design of ultracompact implantable antennas. In this article, we developed a circularly polarized fractal-shaped open-loop antenna for leadless cardiac transcatheter pacing (TCP) system operating at industrial, scientific, and medical bands (915 MHz, 2.4 GHz, and 5.8 GHz). The proposed antenna was constructed on the high permittivity dielectric material Rogers RT/Duroid 6010 LM ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r} = 10$ </tex-math></inline-formula> ) with a tiny footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 3\times0.254$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . To the best of our knowledge, this is the smallest footprint antenna that works in triple bands with circular polarization, compared with the other reported implantable antennas. We placed the antenna inside the TCP system to evaluate its performance in a realistic environment. Subsequently, it is placed deep inside at the center of the multilayer (skin–fat–muscle) phantom model with dielectric properties equivalent to the human heart. Furthermore, the antenna was integrated into a 3-D printed TCP capsule with dummy electronics for experimental verification, and its performance was checked in the ballistic gel phantom and minced pork. The measured impedance bandwidths of the antenna at 915 MHz, 2.4 GHz, and 5.8 GHz are 580 MHz, 900 MHz, and 1.2 GHz, respectively. Correspondingly, the measured axial ratio bandwidths in phantom are 255 MHz, 260 MHz, and 370 MHz, and measured gain values are −35.1 dBi, −31.6 dBi, and −26.7 dBi.

Leadless cardiac pacemaker in elderly patients: How old for a new technology?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Leadless transcatheter pacemakers are considered as a safe and effective option for cardiac pacing in patients (pts) at higher risk of complications with conventional transvenous cardiac pacing. Purpose Our aim was to assess the clinical "real-life" feasibility and outcomes of leadless pacing in elderly pts in a high-volume center over a mid-term follow-up (FU) period. Methods Elderly pts (aged ≥ 75 years) who underwent leadless MICRA® system pacemaker implantation with a FU period above 3 months were included in this retrospective monocentric study. Results 130 pts were included (84 ± 5.6 years old, male 66.2%). Indications were: Atrioventricular block (permanent 15.4%; transient 27.7%), atrial fibrillation bradycardia 50% and sinus node dysfunction 6.9%. Leadless system pacing was preferred over conventional pacing in pts with: transvenous pacemaker extractions due to infectious 18.5% or vascular 1.5% complications; active systemic infection and urgent need for cardiac stimulation 20%; complex conventional vascular approach 21.6%; severe tricuspid valve disease 1.5%; deterioration of general condition and clinical frailty 22.3%; shortly after transvalvular aortic valve replacement 8.5%. Among the pts, 6.2% had previous leadless Nanostim® device implantation with dysfunction of the system. Pts had either local anesthesia 13.2% or deep sedation 86.8%. The average fluoroscopy time was 4.3±2.9 minutes and number of device deployments before the final position ranged from 1 to 7 with a mean value of 1.5±1 positions. Pacing threshold during implant was 0.5±0.4 V at 0.24ms, only 4 pts (3%) had an implant threshold of &amp;gt;1.0 V at 0.24 ms. Two postoperative deaths were observed: 1 cardiac arrest related to myocardial dysfunction and consequent pulmonary edema in a patient with advanced heart failure, and 1 death secondary to myocardial perforation with need for surgical repair that occurred among the first implantations with an apical device position and a patient with multiple comorbidities. The total rate of major complications was 2.3% with only 1 vascular complication at the femoral puncture site. The median time from the leadless pacemaker implant procedure to discharge was 5±6.5 days (minimum 1 and maximum 40 days): 55.6% pts were able to leave the cardiology department within the first 72 hours. The mean FU period was 17 months ± 15 months with a mortality rate of 12.3% (cardiovascular impairment 5.4%; non cardiovascular-related deaths 6.9%). Increase in pacing thresholds was noted in 4 pts with subsequent stabilization; 92.2% of pts presented with thresholds lower than 1V at 0.24 ms. All pts remained free of infections during FU with no cases of device dislodgement observed. Conclusion Elderly pts are at higher risk of complications; our experience confirms their clinical frailty and underlines the favorable safety profile of leadless system pacing with a low rate of complications and stable pacing thresholds.

PO-693-05 REMOVAL OF A CHRONICALLY-IMPLANTED LEADLESS VENTRICULAR PACEMAKER AFTER 9-YEARS USING A HIGHLY TORQUE RETRIEVAL CATHETER A CASE REPORT

Leadless cardiac pacemakers (LPs) are an effective and safe alternative to transvenous pacemakers for single-chamber ventricular pacing. However, the feasibility of retrieving and replacing chronically implanted LPs is not well understood. We report a case of LP retrieval and replacement of a 9-year chronically implanted Nanostim LP. N/A An 84 year old woman had a Nanostim LP (St Jude Medical Inc) implanted in December 2012, with good pacing parameters: threshold 0.5 V at 0.4 ms, impedance 500 Ohm, R-wave amplitude 7.5 mV. The parameters remained stable over time until the most recent clinic visit (early November 2021), when interrogation failed - indicating battery end-of-life. One month later, she underwent LP retrieval. Fluoroscopy revealed significant swinging movement of the LP docking button - suggestive that success of retrieval was likely. After femoral venous access, with fluoroscopy + ICE guidance, we used a tri-loop snare LP retrieval catheter (Abbott Inc) designed to be engage the LP in a highly torque-responsive manner. After confirming coaxial alignment between the snare and the docking button, the snare was closed, and locked around the docking button on the proximal end of the LP. After closing the snare, the retrieval catheter was docked with the LP. The protective sleeve was then advanced over the LP to assist with the coaxial alignment between the retrieval catheter docking cap and the LP. Thereafter, the retrieval catheter was rotated counterclockwise to allow the LP to unscrew from the myocardium. After less than 2 minutes, the tri-Loop retrieval catheter snared the docking cap, and the soft protective sleeve was easily advanced over the LP. After two full rotations, and in less then 2 minutes, the LP was released from the RV wall. The explanted LP device had limited adherent tissue ingrowth. During the same procedure, a new LP (Aveir VR; Abbott Inc.) was implanted: acute threshold 1 V/0.4, Impedance 630 ohm and R wave amplitude 9 mV. This case report demonstrates the feasibility of retrieval of even long-term chronically-implanted LPs after 9 years duration. Successful retrieval seems to be related to the combination of i) identifying swinging motion of the LP with fluoroscopy, plus ii) the high torque-responsiveness of the retrieval catheter.

Design and implementation of compact dual-band conformal antenna for leadless cardiac pacemaker system

The leadless cardiac pacemaker is a pioneering device for heart patients. Its rising success requires the design of compact implantable antennas. In this paper, we describe a circularly polarized Hilbert curve inspired loop antenna. The proposed antenna works in the WMTS (Wireless Medical Telemetry Services) 1.4 GHz and ISM (Industrial, Scientific, and Medical) 2.45 GHz bands. High dielectric constant material Rogers RT/Duroid 6010 LM ({epsilon }_{r}=10) and fractal geometry helps to design the antenna with a small footprint of 9.1 mm3 (6 mm × 6 mm × 0.254 mm). The designed antenna has a conformal shape that fits inside a leadless pacemaker’s capsule is surrounded by IC models and battery, which are tightly packed in the device enclosure. Subsequently, the integrated prototype is simulated deep inside at the center of the multi-layer canonical heart model. To verify experimentally, we have put dummy electronics (IC and battery) inside the 3D printed pacemaker’s capsule and surfaced the fabricated conformal antenna around the inner curved body of the TCP (Transcatheter Pacing) capsule. Furthermore, we have tested the TCP capsule by inserting it in a ballistic gel phantom and minced pork. The measured impedance bandwidths at 1.4 GHz and 2.45 GHz are 250 MHz and 430 MHz, whereas measured gains are − 33.2 dBi, and − 28.5 dBi, respectively.

Indication of Leadless Cardiac Pacemaker in Children

Indication of Leadless Cardiac Pacemaker in Children

Single-Chamber Leadless Cardiac Pacemaker in Patients Without Atrial Fibrillation: Findings From Campania Leadless Registry.

Introduction:Little is known about the clinical performance of single-chamber leadless pacemaker (LLPM) in patients without atrial fibrillation (AF) as pacing indication. The aim of this study was to describe the clinical characteristics of patients who underwent single chamber LLPM implantation at three tertiary referral centers and to compare the safety and effectiveness of the single-chamber LLPM among patients with or without AF.Materials and Methods:All the consecutive patients who underwent LLPM implantation at three referral centers were analyzed. The indications to LLPM in a real-world setting were described. The study population was divided into two groups according to AF as pacing indication. We assessed the procedure-related complications; moreover, we compared syncope, cardiac hospitalization, pacemaker syndrome, and all-cause death recurrence during the follow-up between patients with and without AF as pacing indication.Results:A total of 140 consecutive patients (mean age, 76.7 ± 11.24 years, men 64.3%) were included in the study. The indication to implantation of LLPM was permanent AF with slow ventricular response (n: 67; 47.8%), sinus node dysfunction (n: 25; 17.8%), third atrioventricular block (AVB) (n: 20; 14.2%), second-degree AVB (n: 18; 12.8%), and first degree AVB (n: 10; 7.1%). A total of 7 patients (5%) experienced perioperative complications with no differences between the AF vs. non-AF groups. During a mean follow-up of 606.5 ± 265.9 days, 10 patients (7.7%) died and 7 patients (5.4%) were reported for cardiac hospitalization; 5 patients (3.8%) experienced syncope; no patients showed pacemaker syndrome. No significant differences in the clinical events between the groups were shown. The Kaplan–Meier analysis for the combined endpoints did not show significant differences between the AF and non-AF groups [hazard ratio (HR): 0.94, 95% CI: 0.41–2.16; p = 0.88].Conclusion:Our real-world data suggest that LLPM may be considered a safe and reasonable treatment in patients without AF in need of pacing. Further studies are needed to confirm these preliminary results.

Ventricular Fibrillation Cardiopulmonary Arrest Following Micra™ Leadless Pacemaker Implantation

Leadless cardiac pacemakers such as the Micra™ transcatheter leadless pacing system (Medtronic, Minneapolis, MN, USA) are an alternative to traditional transvenous pacemakers. Implantation of leadless pacemakers, albeit safe, may be associated with complications, including cardiac tamponade; high capture thresholds; and, rarely, ventricular arrhythmias. We report a case of ventricular fibrillation arrest following the implantation of a Micra™ leadless pacemaker.

Inductive Power Transfer Link at 13.56 MHz for Leadless Cardiac Pacemakers

Inductive power links are most viable for the long-term powering of cardiac pacemakers. Designing an inductive power link without surpassing the specific absorption rate (SAR) for modern leadless cardiac pacemakers (LCPs) remains a challenging task because of its size and implantation depth. The inductive power link employed in the conventional works is either designed at a high frequency or based on the size, shape, weight, and implantation depth of conventional cardiac pacemakers. Here, a 3-coil inductive power transfer link with a circular transmitter coil and solenoidal receiver coil is designed at 13.56 MHz to provide uninterrupted power to the modern LCPs. Considering the food and drug administration approved term for implant size of modern LCP, the receiver coil is designed with 6 mm diameter and 6.5 mm length. The performance of the link has been verified through simulations and measurements under perfect alignment, lateral and/or angular misalignments, and distance variation between the coils. At a 50 mm horizontal distance between transmitter and receiver coils, the transmission coefficient is −30.9 dB. The maximum simulated average SAR at heterogeneous phantom is 0.30 W/kg, which is lower than the limit set by the Federal Communications Commission for radiation threshold exposure. Experiments conducted on pork’s heart verified the reliability of the simulated results. At a 50 mm distance between the coils, the measured transmission coefficient is −34 dB, and at an input power of 1 W, the power delivered to the load is 0.7 mW.

B-PO05-061 SAFETY OF INTRAOPERATIVE PLACEMENT OF PERMANENT LEADLESS PACEMAKERS COMPARED TO TEMPORARY EPICARDIAL WIRE PLACEMENT

Since the risk of post-op bradyarrhythmias is high after tricuspid valve or aortic valve surgery, placement of temporary epicardial pacing (TEP) wires has a Class I indication. Intraoperative placement of a leadless cardiac pacemaker (LCP) avoids the need for monitoring with TEP and their associated complications. To compare the safety of intraoperative LCP against post-operative monitoring with TEP wires in patients who ultimately undergo pacemaker placement. Single-center review of patients who underwent valve surgery from 8/2018-11/2020 and received an LCP (Medtronic, Micra) either i) intraoperatively without adjunctive TEP wires (n=23; Figure) or ii) post-operatively with TEP (n = 23). There were no procedural complications/adverse pacing events with intra-operative LCP implantation without TEP wire placement. Of patients with TEP in place, two (8.7%) required urgent implantation of transvenous pacing leads after pacing needs developed post-TEP removal. One patient received an urgent permanent pacemaker after TEP leads failed and lost capture. TEP wires remained in place for a median of 9 days. Despite additional monitoring in the TEP group, both groups had similar rates of moderate pacing (>40% RV pacing) at 30-day follow-up (44% TEP vs 28% Intraop, p = 0.298). There were no pacing related complications in patients who underwent intraoperative LCP implantation without temporary epicardial leads. Temporary epicardial leads have been associated with pacing related complications (R-on-T) and can fail over time. Studies on the financial implications of this strategy are warranted.

Leadless cardiac pacemaker implantations after infected pacemaker system removals in octogenarians.

BackgroundManagement of pacemaker (PM) infections among advanced aged patients possesses particular clinical challenges due to higher rates of concurrent cardiovascular disease and medical comorbidities. Novel leadless cardiac pacemakers (LCPs) may provide new opportunities for better management options in this population, however, there is limited data especially in Asian populations to guide the decision making.MethodsWe reviewed 11 octogenarians (median age: 86 [minimum 82–maximum 90] years; male: 73%; median body mass index (BMI): 20.1 kg/m2) who received Micra Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) implantations following transvenous lead extractions (TLEs) for PM infections. ResultsAll patients had more than two medical comorbidities (average 3.7 comorbidities). The indications for LCP implantations were atrioventricular block in four patients, atrial fibrillation bradycardia in five, and sinus node dysfunction in two. Eight patients (73%) were bridged with temporary pacing using active fixation leads (median interval of 14.0 days), while one with severe dementia underwent a concomitant LCP implantation and TLE during the same procedure. Successful TLEs and LCP implantations were successfully accomplished in all without any complications. The median time from the TLE procedure to discharge was 22 days (minimum 7–maximum 136). All patients remained free of infections during a mean follow-up period of 17.2 ± 6.5 months.ConclusionsLCP implantations were safe and effective after removing the entire infectious PM system in all octogenarians. The novel LCP technology may offer an alternative option for considering a re-implantation strategy after transvenous PM infections in elderly patients, particularly those with severe frailty and PM dependency.

B-PO03-036 IMPACT OF LEADLESS PACEMAKER IMPLANTATION DURING VALVE SURGERY ON LENGTH OF STAY

The leadless cardiac pacemaker (LCP) is typically implanted percutaneously, but can also be implanted under direct visualization during valve surgery in patients with either a pre-existing pacing indication or who are at high risk for post-op bradyarrhythmias. To compare the impact of timing of LCP implantation on the length of hospitalization in patients undergoing intra-operative (during valve surgery) vs post-operative (prior to discharge) leadless pacemaker implantation. We conducted a retrospective review of patients undergoing valve surgery between 8/1/2018 and 11/30/2020, and received an LCP (Micra, Medtronic Inc) either intra-operatively (n=27) or post-operatively (n=23) during the index hospitalization. The STS short-term risk scores for mortality and/or morbidity were similar between the intra-operative and post-operative groups (1.6 vs 2.3%, p = 0.646; 14.6 vs 12.7%, p = 0.437, respectively). Patients receiving an intra-operative LCP spent significantly fewer median days in the ICU (3 vs 5 days, p = 0.03) and had a significantly shorter median total length of stay (11 vs 16 days, p = 0.036). Despite similar pre-operative co-morbidities, intra-operative implantation of an LCP in select patients at high risk for post-operative bradyarrhythmias is associated with a significantly shorter lengths of stay in both the ICU and the hospital. Future studies should identify which patients may benefit most from this prophylactic approach to pacing in at-risk patients undergoing valve surgery.

Gerätebasierte rhythmologische Diagnostik und Therapie in COVID-19-Zeiten

Die COVID-Pandemie mit ihrer ersten und zweiten Welle hat uns gezwungen, über eine sinnvolle Nutzung unserer medizinischen Ressourcen nachzudenken und Eingriffe nach ihrer Notwendigkeit und Dringlichkeit zu graduieren. Diese Selektion ist insbesondere in der Kardiologie in jedem einzelnen Fall schwierig und riskant. Die aktuellen Empfehlungen in der Herzschrittmacher‑, Defibrillatortherapie und Nachsorge werden aufgezeigt mit dem Ziel, die individuelle ärztliche Entscheidung auf nachvollziehbare und belastbare Argumente zu stützen und diese auch den Patienten gegenüber begründen zu können. Diese Überlegungen haben in einzelnen Ländern zu einem deutlichen Rückgang von Schrittmacher- und Defibrillatorimplantationen geführt ebenso wie Ablation bei supraventrikulären Arrhythmien. Die Auswirkungen der Pandemie lassen sich aus den Aktivitätsprofilen der rhythmologischen Implantate nachvollziehen. Die Notwendigkeit und Chancen einer telemedizinischen Überwachung sind in dieser Zeit nachdrücklich deutlich geworden, ebenso wie die bislang unzureichende Nutzung und mangelnde Struktur. Die aktuelle positive G‑BA(Gemeinsamer Bundesausschuss)-Bewertung der telemedizinischen Überwachung bei Herzinsuffizienz weist in die richtige Richtung, die Umsetzung und Vergütung wird jedoch für weitere Diskussionen sorgen. Ein neuer Algorithmus, der auf einer Herztonerkennung beruht und im ersten AV(atrioventrikulären)-sequenziellen sondenlosen Herzschrittmacher Verwendung findet, wird diskutiert. Bisher stützen sich die Indikationen für eine primärprophylaktische ICD(implantierbarer Kardioverter-Defibrillator)-Implantation im Wesentlichen auf die linksventrikuläre Ejektionsfraktion insbesondere bei der nichtischämischen Kardiomyopathie. Die Notwendigkeit und Bedeutung von intramuralem Fibrose- und Narbennachweis in der Magnetresonanztomographie (MRT) werden diskutiert und könnten die Entscheidungsfindung unterstützen.

Editor's comments

Most of the more than one million cardiac pacemakers implanted each year have up to three leads that reach into the heart's chambers. The most modern pacemakers integrate all of the pacemaker functions into a small capsule that be directly implanted into the endocardium, resulting in what is known as a leadless cardiac pacemaker. However, these can typically only be used to stimulate a single chamber. By using intra-body communication, the operation of more than one leadless cardiac pacemaker can be synchronized, resulting in the ability to use this approach with multiple chambers of the heart. The paper by Mirko Maldari, Chadi Jabbour, Youcef Haddab, and Patricia Desgreys describes a system for such intra-body communication for pacemakers. The design and development of the system is described, as well as the optimization of the power usage of the system based on the signal waveform involved. The results demonstrated the telemetry-based synchronization of a dual-chamber leadless cardiac pacemaker system with minimum power consumption. This paper was based on one of the finalists for the 2021 URSI-France PhD Prize in Radio Science.

Conductive Impulse for Wireless Communication in Dual-Chamber Leadless Pacemakers

Conductive impulse signaling is proposed for high-efficiency low data-rate wireless communication for future development in cardiac leadless pacemaker technology. The conductivity of the heart muscles and blood is used for electrical signal transmission between two pacemaker implants in the right atrium and the right ventricle. The communication channel is characterized in the frequency range of 1–15 MHz using numerical electromagnetic computations. The wideband implant electrodes support the impulse signaling, and the frequency flat communication channel prevents impulse distortion that simplifies the receiver design using a threshold detector scheme. An ultralow-power impulse generator is designed using off-the-shelf electronics and is integrated into a leadless pacemaker mockup, and the impulse transmission between two capsules is measured in a homogeneous phantom and in vivo animal heart experiments. The feasibility of system integration with the state-of-the-art leadless cardiac pacemakers is demonstrated that can support ultralow-power, low data-rate wireless communications.

European experience with a first totally leadless cardiac resynchronization therapy pacemaker system.

AimsTotally leadless cardiac resynchronization therapy (CRT) can be delivered with a combination of Micra and WiSE-CRT systems. We describe the technical feasibility and first insights into the safety and efficacy of this combination in European experience.Methods and resultsPatients enrolled had indication for both Micra and WiSE-CRT systems because of heart failure related to high burden of pacing by a Micra necessitating system upgrade or inability to implant a conventional CRT system because of infectious or anatomical conditions. The endpoints of the study were technical success of WiSE-CRT implantation with right ventricle-synchonized CRT delivery, acute QRS duration reduction, and freedom from procedure-related major adverse events. All eight WiSE-CRT devices were able to detect the Micra pacing output and to be trained to deliver synchronous LV endocardial pacing. Acute QRS reduction following WiSE-CRT implantation was observed in all eight patients (mean QRS 204.38 ± 30.26 vs. 137.5 ± 24.75 mS, P = 0.012). Seven patients reached 6 months of follow-up. At 6 months after WiSE-CRT implantation, there was a significant increase in LV ejection fraction (28.43 ± 8.01% vs. 39.71 ± 11.89%; P = 0.018) but no evidence of LV reverse remodelling or improvement in New York Heart Association class.ConclusionThe Micra and the WiSE-CRT systems can successfully operate together to deliver total leadless CRT to a patient. Moreover, the WiSE-CRT system provides the only means to upgrade the large population of Micra patients to CRT capability without replacing the Micra. The range of application of this combination could broaden in the future with the upcoming developments of leadless cardiac pacing.

Leadless pacemaker implantation under direct visualization during valve surgery

ObjectiveThe leadless cardiac pacemaker is typically implanted percutaneously and has been widely used for patients who have already undergone valve surgery. We sought to determine the feasibility and safety of implanting the leadless pacemaker under direct visualization during valve surgery. MethodsWe performed a retrospective analysis of consecutive adult patients (n = 15) who underwent implantation of a leadless pacemaker under direct visualization at the time of valve surgery. Indications for single-chamber pacing were sick sinus syndrome with pauses (53.3%), atrial fibrillation with slow ventricular rates (13.3%) or complete heart block (6.6%), and elevated risk for postoperative heart block (26.6%). Leadless pacemaker performance and pacing percentage were assessed. ResultsPatients' age was 67.5 ± 17 years, 6 patients (40%) were male, and 14 patients (93%) had atrial fibrillation. Isolated tricuspid valve replacement was performed in 5 patients (33.3%), and the remainder underwent multivalve surgery that included concomitant tricuspid valve repair/replacement. In 93% of the patients (n = 14), the immediate post–cardiopulmonary bypass pacing thresholds were normal (≤2.0 V at 0.24 ms) and normalized in the remaining patient by the next morning. The impedance/sensing values were normal and stable through follow-up (151 ± 119 days) in all patients. Reliable leadless pacemaker performance allowed for deferral of temporary epicardial wires in 11 patients (73%). There were no procedural complications or device malfunction. ConclusionsLeadless cardiac pacemaker implantation during valve surgery is feasible and safe. This hybrid approach to pacing may simplify the perioperative management of patients undergoing valve surgery who have an indication for single-chamber pacing.