Conduction system pacing (CSP) is being increasingly adopted as a more physiological alternative to right ventricular and biventricular pacing. Since the 2021 European Society of Cardiology pacing guidelines, there has been growing evidence that this therapy is safe and effective. Furthermore, left bundle branch area pacing was not covered in these guidelines due to limited evidence at that time. This Clinical Consensus Statement provides advice on indications for CSP, taking into account the significant evolution in this domain.

• Keywords
• Biventricular pacing, Cardiac resynchronization therapy, Conduction system pacing, His bundle pacing, Indications, Left bundle branch area pacing,
• MeSH
• Action Potentials MeSH
• Cardiology * standards   MeSH
• Cardiac Pacing, Artificial * standards   adverse effects   methods   MeSH
• Consensus MeSH
• Humans MeSH
• Heart Conduction System * physiopathology   MeSH
• Societies, Medical MeSH
• Arrhythmias, Cardiac * therapy   physiopathology   diagnosis   MeSH
• Heart Rate MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Practice Guideline MeSH
• Geographicals
• Europe MeSH

INTRODUCTION: Left bundle branch area pacing (LBBAP) comprises pacing at the left ventricular septum (LVSP) or left bundle branch (LBBP). The aim of the present study was to investigate the differences in ventricular electrical heterogeneity between LVSP, LBBP, right ventricular pacing (RVP) and intrinsic conduction with different dyssynchrony measures using the ECG, vectorcardiograpy, ECG belt, and Ultrahigh frequency (UHF-)ECG. METHODS: Thirty-seven patients with a pacemaker indication for bradycardia or cardiac resynchronization therapy underwent LBBAP implantation. ECG, vectorcardiogram, ECG belt and UHF-ECG signals were recorded during RVP, LVSP and LBBP, and intrinsic activation. QRS duration (QRSd) was measured from the ECG, QRS area was calculated from the vectorcardiogram, LV activation time (LVAT) and standard deviation of activation time (SDAT) from ECG belt and electrical dyssynchrony (e-DYS16) from UHF-ECG. RESULTS: Both LVSP and LBBP significantly reduced ventricular electrical heterogeneity as compared to underlying LBBB and RV pacing in terms of QRS area (p < .001), SDAT (p < .001), LVAT (p < .001) and e-DYS16 (p < .001). QRSd was only reduced as compared to RV pacing(p < .001). QRS area was similar during LBBP and normal intrinsic conduction, e-DYS16 was similar during LVSP and normal intrinsic conduction, whereas SDAT was similar for LVSP, LBBP and normal intrinsic conduction. For all these variables there was no significant difference between LVSP and LBBP. CONCLUSION: Both LVSP and LBBP resulted in a more synchronous LV activation than LBBB and RVP. Especially LBBP resulted in levels of LV synchrony comparable to normal intrinsic conduction.

• Keywords
• bradycardia pacing, cardiac resynchronization therapy, conduction system pacing, dyssynchrony, left bundle branch area pacing,
• MeSH
• Action Potentials * MeSH
• Bundle-Branch Block physiopathology   therapy   diagnosis   MeSH
• Bradycardia physiopathology   therapy   diagnosis   MeSH
• Time Factors MeSH
• Electrophysiologic Techniques, Cardiac MeSH
• Electrocardiography MeSH
• Ventricular Function, Left * MeSH
• Bundle of His * physiopathology   MeSH
• Cardiac Pacing, Artificial * MeSH
• Middle Aged MeSH
• Humans MeSH
• Ventricular Septum * physiopathology   MeSH
• Predictive Value of Tests * MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Heart Rate * MeSH
• Cardiac Resynchronization Therapy MeSH
• Vectorcardiography * methods   MeSH
• Treatment Outcome MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH

From precordial ECG leads, the conventional determination of the negative derivative of the QRS complex (ND-ECG) assesses epicardial activation. Recently we showed that ultra-high-frequency electrocardiography (UHF-ECG) determines the activation of a larger volume of the ventricular wall. We aimed to combine these two methods to investigate the potential of volumetric and epicardial ventricular activation assessment and thereby determine the transmural activation sequence. We retrospectively analyzed 390 ECG records divided into three groups-healthy subjects with normal ECG, left bundle branch block (LBBB), and right bundle branch block (RBBB) patients. Then we created UHF-ECG and ND-ECG-derived depolarization maps and computed interventricular electrical dyssynchrony. Characteristic spatio-temporal differences were found between the volumetric UHF-ECG activation patterns and epicardial ND-ECG in the Normal, LBBB, and RBBB groups, despite the overall high correlations between both methods. Interventricular electrical dyssynchrony values assessed by the ND-ECG were consistently larger than values computed by the UHF-ECG method. Noninvasively obtained UHF-ECG and ND-ECG analyses describe different ventricular dyssynchrony and the general course of ventricular depolarization. Combining both methods based on standard 12-lead ECG electrode positions allows for a more detailed analysis of volumetric and epicardial ventricular electrical activation, including the assessment of the depolarization wave direction propagation in ventricles.

• MeSH
• Bundle-Branch Block diagnosis   MeSH
• Electrocardiography * methods   MeSH
• Humans MeSH
• Retrospective Studies MeSH
• Arrhythmias, Cardiac MeSH
• Heart Ventricles * diagnostic imaging   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

Identifying electrical dyssynchrony is crucial for cardiac pacing and cardiac resynchronization therapy (CRT). The ultra-high-frequency electrocardiography (UHF-ECG) technique allows instantaneous dyssynchrony analyses with real-time visualization. This review explores the physiological background of higher frequencies in ventricular conduction and the translational evolution of UHF-ECG in cardiac pacing and CRT. Although high-frequency components were studied half a century ago, their exploration in the dyssynchrony context is rare. UHF-ECG records ECG signals from eight precordial leads over multiple beats in time. After initial conceptual studies, the implementation of an instant visualization of ventricular activation led to clinical implementation with minimal patient burden. UHF-ECG aids patient selection in biventricular CRT and evaluates ventricular activation during various forms of conduction system pacing (CSP). UHF-ECG ventricular electrical dyssynchrony has been associated with clinical outcomes in a large retrospective CRT cohort and has been used to study the electrophysiological differences between CSP methods, including His bundle pacing, left bundle branch (area) pacing, left ventricular septal pacing and conventional biventricular pacing. UHF-ECG can potentially be used to determine a tailored resynchronization approach (CRT through biventricular pacing or CSP) based on the electrical substrate (true LBBB vs. non-specified intraventricular conduction delay with more distal left ventricular conduction disease), for the optimization of CRT and holds promise beyond CRT for the risk stratification of ventricular arrhythmias.

• Keywords
• cardiac resynchronization therapy, conduction system pacing, electrical dyssynchrony, electrocardiography, ultra-high frequency,
• Publication type
• Journal Article MeSH
• Review MeSH

In contrast to left bundle branch pacing, the criteria for left ventricular septal pacing (LVSP) were never validated. LVSP is usually defined as deep septal deployment of the pacing lead with a pseudo-right bundle branch morphology in V1. The case report describes an implant procedure during which this definition of LVSP was fulfilled in four of five pacing locations within the septum, with the shallowest of them present in less than 50% of the septal thickness. The case highlights the need for a more precise definition of LVSP.

• Publication type
• Journal Article MeSH
• Case Reports MeSH

[Figure: see text]

• MeSH
• Electrocardiography MeSH
• Ventricular Function, Left MeSH
• Bundle of His MeSH
• Cardiac Pacing, Artificial MeSH
• Humans MeSH
• Heart Conduction System * MeSH
• Heart Ventricles diagnostic imaging   MeSH
• Cardiac Resynchronization Therapy * MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Publication type
• Comment MeSH
• Editorial MeSH

Biventricular pacing (Biv) and left bundle branch area pacing (LBBAP) are methods of cardiac resynchronization therapy (CRT). Currently, little is known about how they differ in terms of ventricular activation. This study compared ventricular activation patterns in left bundle branch block (LBBB) heart failure patients using an ultra-high-frequency electrocardiography (UHF-ECG). This was a retrospective analysis including 80 CRT patients from two centres. UHF-ECG data were obtained during LBBB, LBBAP, and Biv. Left bundle branch area pacing patients were divided into non-selective left bundle branch pacing (NSLBBP) or left ventricular septal pacing (LVSP) and into groups with V6 R-wave peak times (V6RWPT) < 90 ms and ≥ 90 ms. Calculated parameters were: e-DYS (time difference between the first and last activation in V1-V8 leads) and Vdmean (average of V1-V8 local depolarization durations). In LBBB patients (n = 80) indicated for CRT, spontaneous rhythms were compared with Biv (39) and LBBAP rhythms (64). Although both Biv and LBBAP significantly reduced QRS duration (QRSd) compared with LBBB (from 172 to 148 and 152 ms, respectively, both P < 0.001), the difference between them was not significant (P = 0.2). Left bundle branch area pacing led to shorter e-DYS (24 ms) than Biv (33 ms; P = 0.008) and shorter Vdmean (53 vs. 59 ms; P = 0.003). No differences in QRSd, e-DYS, or Vdmean were found between NSLBBP, LVSP, and LBBAP with paced V6RWPTs < 90 and ≥ 90 ms. Both Biv CRT and LBBAP significantly reduce ventricular dyssynchrony in CRT patients with LBBB. Left bundle branch area pacing is associated with more physiological ventricular activation.

• Keywords
• Biv CRT, Heart failure, LBBAP, UHF-ECG, Ventricular synchrony,
• Publication type
• Journal Article MeSH

The conduction system of the human heart is composed of specialized cardiomyocytes that initiate and propagate the electric impulse with consequent rhythmic and synchronized contraction of the atria and ventricles, resulting in the normal cardiac cycle. Although the His-Purkinje system (HPS) was already described more than a century ago, there has been a recent resurgence of conduction system pacing (CSP), where pacing leads are positioned in the His bundle region and left bundle branch area to provide physiological cardiac activation as alternatives to the unnatural myocardial stimulation obtained with conventional right ventricular and biventricular pacing. In this review, we describe the fundamental anatomical and pathophysiological aspects of the specialized HPS along with the CSP technique's nuts and bolts to highlight its potential benefits in everyday clinical practice.

• Keywords
• Conduction system pacing, His-bundle pacing, His–Purkinje system, Left bundle branch area pacing, Ultra-high-frequency electrocardiogram,
• Publication type
• Journal Article MeSH

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last five years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique.

• Keywords
• Conduction system pacing, Device implantation, His bundle pacing, Left bundle branch area pacing,
• MeSH
• Bundle of His MeSH
• Humans MeSH
• Cardiac Conduction System Disease MeSH
• Heart Conduction System * MeSH
• Cardiac Resynchronization Therapy * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Canada MeSH
• Latin America MeSH

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique. A synopsis is provided in this print edition of EP-Europace. The full document may be consulted online, and a 'Key Messages' App can be downloaded from the EHRA website.

• Keywords
• Conduction system pacing, Device implantation, His bundle pacing, Left bundle branch area pacing,
• MeSH
• Humans MeSH
• Cardiac Conduction System Disease MeSH
• Heart Conduction System * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Asia MeSH
• Canada MeSH