The jugular approach for leadless pacing: A novel and safe alternative.

AIMS: To evaluate safety of leadless pacemaker implantation through the internal jugular vein in a larger cohort with longer follow-up. Moreover, feasibility of non-apical pacing as well as relation between pacing site and QRS duration were assessed. METHODS: Eighty Two consecutive patients, who received a leadless pacemaker though the internal jugular vein, were included. Electrical parameters were measured at regular follow-up and any complications were registered. Paced QRS interval was compared for three pacing sites, RVOT, RV mid septum, and RV apical septum. RESULTS: In all patients, the leadless pacemaker was implanted successfully. In 69 patients, the device was implanted in a non-apical position. In 71% of cases, the device could be deployed at first attempt. The median fluoroscopy time was 4.4 min (range 0.9-51) The paced QRS interval was significantly narrower for non-apical pacing sites compared to apical pacing si 156  vs. 179 ms. p = .04, respectively. During mean follow-up of 16 months (range 0-43 months), electrical parameters remained stable. Two complications occurred, which could be resolved during the implant procedure. There were no access site related complications. CONCLUSION: The jugular approach for leadless pacemaker implantation is feasible and may avoid vascular complications. It facilitates non-apical positioning of leadless pacemakers leading to a narrower paced QRS interval. The jugular approach allows for immediate post procedural ambulation.

Physical activity detection in patients with intracardiac leadless pacemaker.

INTRODUCTION: The Micra Transcatheter Pacing System provides a rate adaptive pacing using an individually programmable three-axis accelerometer. We evaluated the short- and mid-term performance of the Micra activity sensor by testing all three available activity vectors during the exercise tests. METHODS AND RESULTS: Implantation and follow-up data were prospectively collected from the patients undergoing Micra implantation at our institution. Patients underwent a 5-minute exercise test for each vector at predischarge (initial testing) and at scheduled in-office visits (repeat testing). On the basis of measurements of activity counts during the test, vectors were categorized to be adequate (excellent or acceptable) or poor. A total of 278 tests with 818 vector measurements were analyzed in 51 patients during follow-up (median duration was 18 months). Initial testing revealed the adequate quality of the nominal Vector 1 in 74.5% of the patients. Upon repeated testing at subsequent in-office visits, Vectors 1 and 3 were comparable (adequate quality in 64.7% vs 68.6% of the patients; P = 0.65) but better compared with Vector 2 (51.0%; P = 0.10 vs Vector 1, P = 0.01 vs Vector 3). In a subgroup of 45 patients programmed to VVIR mode, Vector 1 was selected in 46.7% of the patients after the initial test (Vector 2, 8.9%; Vector 3, 44.4%). Vector change was performed in 10 patients (22.2%) following repeated tests within 3 months of postimplantation. CONCLUSION: The three-axis accelerometer-based rate adaptive pacing feature proved to be feasible after manual selection of an adequate activity vector. Vector testing in Micra patients with chronotropic incompetence appears to be beneficial compared with the use of nominal Vector 1.

The fixation tines of the Micra™ leadless pacemaker are atraumatic to the tricuspid valve.

BACKGROUND: Today, there is no manufacturer-supplied retrieval tool for the Micra™ pacemaker (Medtronic, Minneapolis, MN, USA); therefore, off-the-shelf catheters have been employed for retrievals. The proximal retrieval feature of the Micra™ can be snared and the device is then retracted from the myocardium, pulling the device through the tricuspid valve. This study characterizes the potential risks of Micra™ nitinol tine engagement with the tricuspid sub-valvular apparatus. METHODS: Fresh human hearts nonviable for transplant (n = 10) were obtained from our regional organ procurement agency (LifeSource, Minneapolis, MN, USA). Micra™ fixation tines were affixed to a linear force transducer. Tines were then engaged in tricuspid chordae tendineae to conduct a constant velocity tensile test. Each test was run until tines disengaged from the chordae tendineae or until they released from the valve apparatus. Subsequently, biomechanical failure properties of the valve apparatus and isolated chordae tendineae were determined using a series of uniaxial tensile tests. RESULTS: There were no chordal ruptures observed during our Micra™ tine extraction testing. Chordal failure required 15.0 times the force of extracting a single engaged tine, and 9.0 times the force of extracting two engaged tines. The uniaxial stresses required for isolated chordal failure averaged 17.4 N/mm2 ; failure strains exceeded 150% resting chordal length. CONCLUSIONS: The forces required to rupture tricuspid chordae tendineae significantly exceeded the forces potentially imposed on the chordae during Micra™ device retrievals. We conclude that the fixation tines of the Micra™ device are unlikely to damage the tricuspid apparatus during either implant or retrieval.

Severe Sinus Bradycardia: An Unusual Cardiac Manifestation of COVID-19.

There has been an accumulating evidence of association between COVID-19 (coronavirus disease 2019) infection and cardiovascular complications. We describe a case of a 58-year-old lady with a history of systolic heart failure and COVID-19 infection, who developed persistent symptomatic bradycardia, requiring pacemaker placement as unusual conductive tissue involvement of this novel coronavirus.

Comparison between leadless and transvenous single-chamber pacemaker therapy in a referral centre for lead extraction.

PURPOSE: The aim of the study was to compare the long-term clinical and electrical performance of Micra leadless pacemaker with transvenous single-chamber pacemaker (TV-VVI PM) in a high-volume centre for transvenous lead extraction (TLE). METHODS: One-hundred patients (group 1) undergoing Micra implant were matched with 100 patients undergoing TV-VVI PM implant (group 2) by age, sex, left ventricular systolic ejection fraction and previous TLE. RESULTS: The implant procedure was successful in all patients. In group 1, the procedure duration was lower than in group 2 (43.86 ± 22.38 vs 58.38 ± 17.85 min, p < 0.001), while the fluoroscopy time was longer (12.25 ± 6.84 vs 5.32 ± 4.42 min, p < 0.001). There was no difference about the rate of septal implant at the right ventricle (76% vs 86%, p = 0.10). Patients were followed-up for a median of 12 months. No acute and chronic procedure-related complication was observed in group 1, while we reported acute complications in seven patients (7%, p = 0.02) and long-term complications in three patients (3%, p = 0.24), needing for a system revision in 6 cases (6%, p = 0.038), in group 2. One systemic infection occurred in TV-VVI PM group. Electrical measurements were stable during follow-up in both groups, with a longer estimated battery life in group 1 (mean delivered energy at threshold at discharge: 0.14 ± 0.21 vs 0.26 ± 0.22 µJ, p < 0.001). CONCLUSION: Micra pacemaker implant is a safe and effective procedure, with a lower rate of acute complications and system revisions compared with TV-VVI PM, even in a real-life setting including patients who underwent TLE.