Project description:BackgroundA new intracardiac leadless pacemaker (ILP) has been developed to ensure atrioventricular (AV) synchrony (AVS) during ventricular pacing (VP). Recent studies have shown the feasibility and safety of accelerometer-based atrial sensing and an improvement in AVS among patients with atrioventricular block implanted with the Micra AV ILP (Medtronic Inc., Minneapolis, MN, USA). However, no data exists about the benefits of a VDD ILP in patients wearing a still working VVI Nanostim ILP (St Jude Medical, St Paul, MN, USA). We describe the feasibility of the procedure and the absence of device-related adverse events in the short-term follow-up.Case summaryWe present the case of a 72-year-old man implanted with a VVI ILP (Nanostim, St Jude Medical, St Paul, MN, USA) on May 2014, who has developed symptomatic high percentage of VVI asynchronous pacing and was treated with an upgrade to synchronous AV pacemaker (PM) ILP-Micra AV (Medtronic Inc., Minneapolis, MN, USA), which has improved symptoms and functional class.DiscussionIntracardiac leadless pacemakers represent the best current option for patients requiring PM implantation who are at high risk of infection and bleeding. Our case shows that the new AVS ILP is a good alternative to VVI ILP in patients with sinus rhythm and a strong need for VP.
Project description:BackgroundThe use of transvenous pacing leads is associated with the risk of developing tricuspid valve (TV) dysfunction. This develops through several mechanisms including the failure of leaflet coaptation or direct damage to the TV or to its sub-valvular apparatus and can result in significant tricuspid regurgitation (TR). Multiple approaches to pacemaker implantation after transvenous lead extraction (TLE) or surgical TV repair have been described. Placement of pacing leads across the TV is generally avoided in such circumstances.Case summaryA 66-year-old woman presented with a year-long history of exertional dyspnoea, peripheral oedema, and postural neck pulsations. Her medical history included a dual-chamber pacemaker implantation for sinus node dysfunction 14 years ago. Echocardiography revealed severe lead-related TR. Her case was discussed in our multi-disciplinary team meeting. A decision was made to perform a TLE and implant a leadless pacemaker in an attempt to avoid open-heart surgery if possible. This was reserved as an option in the event of persistent severe TR. Transvenous extraction of the right ventricular lead was performed. The atrial lead was preserved and connected to and AAI device. A Micra AV was implanted allowing for atrioventricular (AV) synchronous pacing.DiscussionWe present the first case of successful implementation of AV sequential pacing using a dual-pacemaker approach involving the use of an AAI pacemaker and a Micra AV device. This was performed after TLE for severe lead-related TR.
Project description:AimsPermanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker.Methods and resultsPatients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms.ConclusionEarly assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial.Clinical trial registrationClinicalTrials.gov ID NCT02004873.
Project description:A subclinical cardiac perforation by a device cup of the Micra™ transcatheter pacing system was suspected in a 78-year-old woman. During the procedure, the device cup was placed on the septum. The contrast media was injected before device deployment and remained outside of the myocardium. Later, a cardiac computed tomography scan visualized a protruded diverticular structure on the right ventricle. The contrast material remained in a pouch within the pericardium. To ensure the device is oriented away from the border between the right ventricular septum and the free wall, right anterior oblique view should be carefully reviewed before deployment.
Project description:The long-term performance of leadless pacemaker (LPM) has not been well evaluated. Between September 2017 and January 2021, 929 consecutive patients who underwent pacemaker implantation were grouped according to the types of pacemakers: LPM (LPM group, n = 368) and conventional pacemaker (PM group, n = 561). The median follow-up duration was 1.7 years (interquartile range 0.8-2.6 years). Hospitalization rate for heart failure in the LPM group was 9.3%, 15.6%, and 21.6% at 1, 2, 3 years, respectively. The LPM group had a significantly higher adjusted heart failure hospitalization risk than the PM group [hazard ratio (HR) 1.70, 95% confidence interval (CI) 1.09-2.64, p = .01]. More patients with symptomatic bradycardia caused by sinus node dysfunction (SND) in the LPM group (n = 150) were admitted to the hospital for heart failure compared to those in the PM group (n = 219) (HR 2.02, 95%CI 1.04-3.90, p = .03), whereas no significant difference was observed between the two groups in the patients with bradycardia caused by atrial fibrillation (LPM group, n = 71; PM group, n = 18) or atrioventricular block (LPM group, n = 147; PM group, n = 324). Patients who received LPM implantation had greater hospitalization risk for heart failure, compared to those who received conventional pacemaker implantation. The increased risk was mainly attributed to patients with SND.
Project description:IntroductionMARVEL 2 assessed the efficacy of mechanical atrial sensing by a ventricular leadless pacemaker, enabling a VDD pacing mode. The behavior of the enhanced MARVEL 2 algorithm during variable atrio-ventricular conduction (AVC) and/or arrhythmias has not been characterized and is the focus of this study.MethodsOf the 75 patients enrolled in the MARVEL 2 study, 73 had a rhythm assessment and were included in the analysis. The enhanced MARVEL 2 algorithm included a mode-switching algorithm that automatically switches between VDD and ventricular only antibradycardia pacing (VVI)-40 depending upon AVC status.ResultsForty-two patients (58%) had persistent third degree AV block (AVB), 18 (25%) had 1:1 AVC, 5 (7%) had variable AVC status, and 8 (11%) had atrial arrhythmias. Among the 42 patients with persistent third degree AVB, the median ventricular pacing (VP) percentage was 99.9% compared to 0.2% among those with 1:1 AVC. As AVC status changed, the algorithm switched to VDD when the ventricular rate dropped less than 40 bpm. During atrial fibrillation (AF) with ventricular response greater than 40 bpm, VVI-40 mode was maintained. No pauses longer than 1500 ms were observed. Frequent ventricular premature beats reduced the percentage of AV synchrony. During AF, the atrial signal was of low amplitude and there was infrequent sensing.ConclusionThe mode switching algorithm reduced VP in patients with 1:1 AVC and appropriately switched to VDD during AV block. No pacing safety issues were observed during arrhythmias.