A Comparison of the Electrophysiological and Anatomic Characteristics of Pacing Different Branches of the Left Bundle Conduction System

Introduction: Left bundle branch pacing (LBBP) is a rapidly growing conduction system pacing technique. However, little is known regarding the electrophysiological characteristics of different types of LBBP. We aimed to evaluate the electrophysiological characteristics and anatomic lead location with pacing different branches of the left bundle branch.Methods: Consecutive bradycardia patients with successful LBBP were enrolled and classified into groups according to the paced electrocardiogram and the lead location. Electrocardiogram, pacing properties, vectorcardiogram, and lead tip location were analyzed.Results: Ninety-one patients were enrolled, including 48 with the left bundle trunk pacing (LBTP) and 43 with the left bundle fascicular pacing (LBFP). The paced QRS duration in the LBTP group was significantly shorter than that in the LBFP group (108.1 ± 9.9 vs. 112.9 ± 11.2 ms, p = 0.03), with a more rightward QRS transition zone (p = 0.01). The paced QRS area in the LBTP group was similar to that during intrinsic rhythm (35.1 ± 15.8 vs. 34.7 ± 16.6 μVs, p = 0.98), whereas in the LBFP group, the paced QRS area was significantly larger compared to intrinsic rhythm (43.4 ± 15.8 vs. 35.7 ± 18.0 μVs, p = 0.01). The lead tip site for LBTP was located in a small fan-shaped area with the tricuspid valve annulus summit as the origin, whereas fascicular pacing sites were more likely in a larger and more distal area.Conclusions: Pacing the proximal left bundle main trunk produced better electrical synchrony compared with pacing the distal left bundle fascicles. A visualization technique can facilitate achieving LBTP.

Percutaneous Treatment of Tricuspid Regurgitation

Tricuspid valve regurgitation is one of the most common valvular disorders and moderate to severe tricuspid regurgitation is consistently associated to an increased morbidity and mortality. From an etiopathological perspective, tricuspid regurgitation can be classified in primary, due to the organic disease of any of the valve components, or secondary, as a result of tricuspid valve annulus dilatation, adverse right ventricular remodeling and tricuspid valve leaflet tethering. Despite its poor prognosis, most patients with tricuspid insufficiency are managed conservatively and only those with concomitant left heart valvular disease do finally go surgery in the real-world setting. In fact, outcomes of conventional surgery in patients with isolated tricuspid regurgitation are poor and this approach has not proven yet any survival benefit over stand-alone medical therapy. Given this unmet need, new transcatheter techniques have been developed in the last years, including leaflet plication, percutaneous annuloplasty and valve implantation in either the tricuspid position (orthotopic implantation) or in a different position such as the vena cava (heterotopic implantation). These techniques, with promising outcomes, are seen as an interesting alternative to open-heart surgery given the much lower periprocedural risk.

Retrieval of a Leadless Transcatheter Pacemaker from the Tricuspid Valve Annulus: A Case Report

This case report describes a procedure of retrieval of a leadless transcatheter pacemaker from the right ventricle after device implantation immediately. An 80-year-old man affected by ischemic cardiomyopathy, complete AV block and atrial fibrillation was implanted with a Micra transcatheter pacing system at the median septum of the right ventricle. After tether removal, the leadless pacemaker migrated to tricuspid valve annulus. The device was successfully removed using a snare loop hooked to the proximal retrieval feature of Micra.

Comparison of electrical characteristics between atrial and ventricular side His-bundle pacing in bradycardia patients

Background His-bundle pacing (HBP) is recognized as the most physiological way of pacing but with less study focused on electrical characteristics in different site. Purpose We aimed to evaluate the differences of pacing and echocardiographic parameters between atrial and ventricular side His-bundle pacing. Methods Patients who successfully underwent HBP implantation from September 2018 to August 2019 were retrospectively analyzed. All patients were assigned to atrial-side HBP (aHBP) group or ventricular-side HBP (vHBP) group according to the location of the His-bundle pacing lead, which was confirmed by two methods including postoperative echocardiography and visualization of tricuspid valve annulus (TVA). The pacing and echocardiographic parameters were compared between two groups during the procedure and at 3-month follow-up. Results A total of 71 bradycardia patients who successfully underwent HBP implantation and confirmed lead position were included. Among them, twenty-seven were assigned to aHBP group and the other 44 were assigned to vHBP group with no significant differences in baseline clinical characteristics between two groups. During the procedure, the proportion of selective HBP was significantly higher (77.8% vs. 11.4%; P<0.01) and the intra-procedural HV intervals was significantly longer (50.85±6.53 ms vs. 42.95±6.02 ms, P<0.01) in aHBP group than in vHBP group. The capture threshold in vHBP group was significantly lower than in aHBP group at implantation (0.92±0.22 V/1.0ms vs. 1.05±0.26 V/1.0ms, P=0.03) and remain significantly difference after 3-month follow-up (0.98±0.23 V/1.0ms vs. 1.15±0.44 V/1.0ms, P=0.03). The R-wave amplitude was significantly higher in vHBP group than in aHBP group at implantation (5.82±2.52 mV vs. 3.74±1.81 mV, P<0.01), and these differences still persisted during follow-up (5.88±2.51 mV vs. 3.67±1.61 mV, P<0.01). During 3-month follow-up, an increase in the capture threshold >1 V/1.0ms was seen in 2 cases in aHBP group while all patients remained stable in vHBP group. One patient developed a pocket hematoma in aHBP group compared to none in vHBP group. None of deterioration of tricuspid regurgitation and other procedure-related complications were observed during 3-month follow-up. Conclusions Ventricular side His-bundle pacing can achieve favourable pacing parameters including a lower pacing threshold and a higher R-wave amplitude than atrial side His-bundle pacing, which may be an ideal pacing strategy for patients in need of ventricular pacing. Funding Acknowledgement Type of funding source: None

Permanent His Bundle Pacing Implantation Facilitated by Visualization of the Tricuspid Valve Annulus

Background: His bundle pacing (HBP) is the most physiological pacing modality. However, HBP has longer procedure times with frequent high capture thresholds, which likely contributes to the low adoption of this approach. The aim of this study is to compare HBP implantation with a novel imaging technique versus the standard implantation technique. Methods: This study included 50 patients with standard pacing indications randomized to HBP with visualization of the tricuspid valve annulus (N=25, the visualization group) or with the standard method (N=25, the control group). In the visualization group, the tricuspid valve annulus was imaged by contrast injection in the right ventricle during fluoroscopy. The site for HBP was identified in relationship to the tricuspid septal leaflet and interventricular septum. Results: Permanent HBP was successful in 92% in the visualization group and 88% in the control group. The fluoroscopic time for HBP lead placement was significantly shorter in the visualization group (7.1±3.3 minutes) compared with the control group (10.1±5.6 minutes, P =0.03). Total procedural and fluoroscopic times were also significantly shorter in the visualization group (91.0±15.7 and 9.6±3.8 minutes) than the control group (104.4±17.8 and 12.7±6.2 minutes, P =0.01 and 0.04, respectively). There was no significant difference in capture threshold between groups. In the visualization group, there was a quantitative association between the HBP site and the tricuspid valve annulus. Conclusions: The visualization technique shortens the procedural and fluoroscopic times for HBP implantation. Moreover, anatomic localization of HBP sites is strongly associated with physiological characteristics of pacing, which can help guide optimal lead placement. Registration: URL: https://www.chictr.org.cn/index.aspx . Unique identifier: ChiCTR2000029834.

Mahaim pathway potential revealed by high-resolution three-dimensional mapping

Mapping and ablation of atriofascicular fibers can be highly challenging due to the complex and dynamic anatomy of the tricuspid valve annulus. This case highlights the utility of a multi-electrode catheter three-dimensional mapping approach to localize the Mahaim pathway along the tricuspid annulus in order to guide catheter ablation.