Preliminary study on left bundle branch area pacing in children：clinical observation of 12 cases

Objective: To explore the safety and feasibility of left bundle branch area pacing (LBBAP) in children. Methods: This study observed 12 children attempted LBBAP from 2019 to 2021 in our department prospectively. Clinical data, pacing parameters, electrocardiograms, echocardiographic measurements and complications were recorded at implant and during follow-up. Results: The 12 patients aged between 3 and 14ys and weighted from 13 to 48kg. 11 patients were diagnosed with third-degree AVB and 1 patient (case 4) suffered from cardiac dysfunction due to right ventricular apical pacing (RVAP). LBBAP was successfully achieved in all patients with narrow QRS complexes. LVEF of case 4 recovered on the 3rd day after LBBAP. The median of LVEDD Z score of the 12 patients decreased from 1.75 to1.05 3 months after implantation (p<0.05). The median of paced QRS duration was 103ms. The median of pacing threshold, R-wave amplitude and impedance were 0.85V, 15mV and 717Ω respectively and remained stable during follow-up. No complications such as loss of capture, lead dislodgement or septal perforation occurred. Conclusions: LBBAP can be performed safely in children with narrow QRS duration and stable pacing parameters. Cardiac dysfunction caused by long-term RVAP can be corrected by LBBAP quickly.

Automated Framework for the Inclusion of a His–Purkinje System in Cardiac Digital Twins of Ventricular Electrophysiology

Personalized models of cardiac electrophysiology (EP) that match clinical observation with high fidelity, referred to as cardiac digital twins (CDTs), show promise as a tool for tailoring cardiac precision therapies. Building CDTs of cardiac EP relies on the ability of models to replicate the ventricular activation sequence under a broad range of conditions. Of pivotal importance is the His–Purkinje system (HPS) within the ventricles. Workflows for the generation and incorporation of HPS models are needed for use in cardiac digital twinning pipelines that aim to minimize the misfit between model predictions and clinical data such as the 12 lead electrocardiogram (ECG). We thus develop an automated two stage approach for HPS personalization. A fascicular-based model is first introduced that modulates the endocardial Purkinje network. Only emergent features of sites of earliest activation within the ventricular myocardium and a fast-conducting sub-endocardial layer are accounted for. It is then replaced by a topologically realistic Purkinje-based representation of the HPS. Feasibility of the approach is demonstrated. Equivalence between both HPS model representations is investigated by comparing activation patterns and 12 lead ECGs under both sinus rhythm and right-ventricular apical pacing. Predominant ECG morphology is preserved by both HPS models under sinus conditions, but elucidates differences during pacing.

How to Implant His Bundle and Left Bundle Pacing Leads: Tips and Pearls

Cardiac pacing is the treatment of choice for the management of patients with bradycardia. Although right ventricular apical pacing is the standard therapy, it is associated with an increased risk of pacing-induced cardiomyopathy and heart failure. Physiological pacing using His bundle pacing and left bundle branch pacing has recently evolved as the preferred alternative pacing option. Both His bundle pacing and left bundle branch pacing have also demonstrated significant efficacy in correcting left bundle branch block and achieving cardiac resynchronisation therapy. In this article, we review the implantation tools and techniques to perform conduction system pacing.

Increased QRS duration and dispersion are associated with mechanical dyssynchrony in patients with permanent right ventricular apical pacing

Background: Permanent right ventricular apical pacing may have negative effects on ventricular function and contribute to development of heart failure. We aimed to assess intra- and interventricular mechanical dyssynchrony in patients with permanent right ventricular apical pacing, and to establish electrocardiographic markers of dyssynchrony. Methods: 84 patients (46:38 male:female) who required permanent pacing were studied. Pacing was done from right ventricular apex in all patients. We measured QRS duration and dispersion on standard 12-lead ECG. Intra- and interventricular mechanical dyssynchrony and left ventricular ejection fraction were assessed by transthoracic echocardiography. Patients were followed-up for 24 months. Results: Six months after implantation, QRS duration increased from 128.02 ms to 132.40 ms, p≤0.05. At 24 months, QRS dispersion increased from 43.26 ms to 46.13 ms, p≤0.05. Intra- and interventricular dyssynchrony increased and left ventricular ejection fraction decreased during follow-up. A QRS dispersion of 47 ms predicted left ventricular dysfunction and long-term electromechanical dyssynchrony with a sensitivity of 80% and a specificity of 76%. Conclusion: In patients with permanent right ventricular apical pacing there is an increased duration and dispersion of QRS related to dyssynchrony and decreased left ventricular ejection fraction. This study shows that QRS dispersion could be a better predictive variable than QRS duration for identifying left ventricular ejection fraction worsening in patients with permanent right ventricular apical pacing. The electrocardiogram is a simple tool for predicting systolic function worsening in these patients and can be used at the bedside for early diagnosis in the absence of clinical symptoms, allowing adjustments of medical treatment to prevent progression of heart failure and improve the patient's quality of life.

Standard stylet-driven Abbott Tendril compared to non-stylet driven Medtronic 3830 in left bundle branch area pacing: procedural duration and acute outcome measures

Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Maatschap cardiologie Isala Zwolle Right ventricular apical pacing (RVAP) is associated with an increased incidence of heart failure, caused by dyssynchronous activation. Left bundle branch area pacing (LBBAP) is an alternative physiological pacing technique. However, evidence on LBBAP is limited. Moreover, most LBBAP has been performed with the lumenless, bipolar, permanent pacing lead, with a fixed helix. Although several case reports described the successful use of a standard stylet-driven lead, only one trial compared a stylet-driven active fixation lead to the Medtronic 3830 lead. The aim of this analysis was to compare the non-stylet driven Medtronic 3830 (MDT) to a standard stylet-driven active fixation lead in terms of pacing parameters, success and complication rates. In this ongoing observational study, 84 patients received a LBBAP in the period of December 2019 until December 2020. The majority received a right ventricular (RV) lead as back-up. A subgroup of 80 patients was selected, including all patients who received the MDT (41.3%) or Tendril lead (58.8%) and had at least a 2-week follow-up period. In both groups 1 LBBAP lead positioning was not successful; 2.1% (Tendril) versus 3.0% (MDT). One patient had a Tendril lead dislocation (2.1%) and therefore switched to the back-up RV lead. The success rate of LBBAP lead performance was comparable, p = 0.632. Complication rate was comparable in both groups, p = 0.441. Mean number of deployments, lead implantation and procedural time did not differ significantly, for Tendril respectively 2.8 ± 2.5 deployments, 47 ± 26 and 107 ± 32 minutes. MDT showed 3.8 ± 3.3 deployments, 48 ± 36 and 123 ± 47 minutes, p-values 0.058, 0.399 and 0.172. Mean sensing amplitude (mV) and pacing threshold (V) were comparable, although Tendril pacing impedance was significantly lower; 439 ± 207 Ohm versus 594 ± 202 Ohm with MDT, p = 0.001. There was no learning effect in the MDT group, comparing the first ten and last ten implantations in implantation time, success rate, number of deployments and complications. The Tendril group showed significantly shorter lead implantation time in the last ten implantations compared to the first ten: 28 ± 15 versus 63 ± 34 minutes, p = 0.002. The last ten Tendril leads were implanted significantly faster than the last ten MDT leads, p = 0.035, with mean lead implantation time for MDT 45 ± 22 minutes. This analysis demonstrates that there are no differences in complications, lead implantation time and number of deployments in LBBAP implantation between MDT and Tendril, although Tendril showed a significant learning effect in lead implantation time. Moreover, success rate did not differ significantly. Pacing impedance was significantly lower in the Tendril group, however this did not result in clinically relevant outcomes. Further research should focus on long-term differences between these leads in terms of pacing parameters and lead failure.

OPTIMIZATION OF RABBIT VENTRICULAR ELECTROPHYSIOLOGICAL MODEL AND SIMULATION OF SYNTHETIC ELECTROCARDIOGRAM

This study aimed to use computer simulation method to study the mechanism of cardiac electrical activities. We optimized an electrophysiological rabbit ventricular model, including myocardial segmentation, heterogeneity and a realistic His-Purkinje network. Simulations of normal state, several types of ventricular premature contractions (VPC), conduction system pacing and right ventricular apical pacing were performed and the detailed cardiac electrical activities were studied from cell level to electrocardiogram (ECG) level. A detailed multiscale optimized ventricular model was obtained. The model effectively simulated various types of electrical activities. The synthetic ECG results were very similar to the real clinical ECG. The duration of QRS of typical VPC is 58[Formula: see text]ms, 71% longer than that of a normal-state synthetic QRS and the amplitude of the QRS is 35% larger, while the QRS duration and amplitude of the real clinical ECG of typical VPC are 69% longer and 36% larger than those of the real normal QRS. The duration of QRS of ventricular fusion beat is 31[Formula: see text]ms, 91% of that of a normal-state synthetic QRS and the amplitude of the QRS is 36% larger, while the QRS duration of the real clinical ECG of a ventricular fusion beat is 92% of the real normal QRS and the amplitude is 37% larger. Therefore, the results indicate that this model is effective and reliable in studying the detailed process of cardiac excitation and pacing.