BACKGROUND: Ultra-high-frequency ECG (UHF-ECG) is a non-invasive tool visualizing the ventricular activation sequence. It was never compared to other methods of dyssynchrony assessment in bradycardia patients. OBJECTIVE: We aimed to compare UHF-ECG interventricular electrical dyssynchrony with interventricular mechanical dyssynchrony measured by echocardiography in patients with right ventricular (RVP) or conduction system pacing (CSP). METHODS: Fifty-three patients with advanced atrio-ventricular conduction disease and preserved ventricular systolic function were prospectively assigned to RVP (n=32) or CSP (n=21). Interventricular mechanical dyssynchrony (IVMD) was measured as a time difference between LV and RV pre-ejection periods. Interventricular e-DYS was software calculated as the time difference between activation in V1 and V7 chest electrodes using UHF-ECG. RESULTS: The median age of patients was 75 years, and both groups had similar clinical characteristics. Baseline IVMD and interventricular e-DYS were similar in the entire population (-2 [-8, 5] ms; resp. -1 [-6, 5] ms; p=0.52). Both methods showed the same dyssynchrony trends after the pacemaker implantation, i.e. while both IVMD and interventricular e-DYS increased in the RVP group (IVMD 28 [23, 33] ms vs. interventricular e-DYS 26 [19, 33] ms, p=0.99), they remained low in the CSP group (IVMD -7 [-16, 2] ms vs. interventricular e-DYS -5 [-12, 2] ms, p=0.91). There was a moderate overall correlation between IVMD and interventricular e-DYS for all studied ventricular rhythms (R=0.74). CONCLUSION: UHF-ECG noninvasively expresses interventricular dyssynchrony from V7-V1 chest leads with similar results to echocardiography. RVP increases interventricular dyssynchrony, while CSP preserves synchronous ventricular activation.

• Keywords
• RV pacing, UHF-ECG, bradycardia, conduction system pacing, echocardiography, ventricular dyssynchrony,
• Publication type
• Journal Article MeSH

Background: Three different ventricular capture types are observed during left bundle branch pacing (LBBp). They are selective LBB pacing (sLBBp), non-selective LBB pacing (nsLBBp), and myocardial left septal pacing transiting from nsLBBp while decreasing the pacing output (LVSP). Study aimed to compare differences in ventricular depolarization between these captures using ultra-high-frequency electrocardiography (UHF-ECG). Methods: Using decremental pacing voltage output, we identified and studied nsLBBp, sLBBp, and LVSP in patients with bradycardia. Timing of ventricular activations in precordial leads was displayed using UHF-ECGs, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. The durations of local depolarizations (Vd) were determined as the width of the UHF-QRS complex at 50% of its amplitude. Results: In 57 consecutive patients, data were collected during nsLBBp (n = 57), LVSP (n = 34), and sLBBp (n = 23). Interventricular dyssynchrony (e-DYS) was significantly lower during LVSP -16 ms (-21; -11), than nsLBBp -24 ms (-28; -20) and sLBBp -31 ms (-36; -25). LVSP had the same V1d-V8d as nsLBBp and sLBBp except for V3d, which during LVSP was shorter than sLBBp; the mean difference -9 ms (-16; -1), p = 0.01. LVSP caused less interventricular dyssynchrony and the same or better local depolarization durations than nsLBBp and sLBBp irrespective of QRS morphology during spontaneous rhythm or paced QRS axis. Conclusions: In patients with bradycardia, LVSP in close proximity to LBB resulted in better interventricular synchrony than nsLBBp and sLBBp and did not significantly prolong depolarization of the left ventricular lateral wall.

• Keywords
• UHF-ECG, depolarization duration, dyssynchrony, left bundle branch pacing, left septal myocardial pacing,
• Publication type
• Journal Article 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

• Keywords
• Heart failure, LBBAP, Resynchronization, UHF-ECG,
• Publication type
• Journal Article MeSH

BACKGROUND: The effect of left ventricular septal myocardial pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and left ventricular (LV) hemodynamic status is poorly understood. OBJECTIVES: The aim of this study was to investigate the impact of LVSP and LBBP vs biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamic status in cardiac resynchronization therapy patients. METHODS: In cardiac resynchronization therapy candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRS duration (QRSd) and using ultra-high-frequency electrocardiography. LV electrical dyssynchrony was assessed as the difference between the first activation in leads V1 to V8 to the last from leads V4 to V8. LV hemodynamic status was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP. RESULTS: A total of 35 patients with a mean LV ejection fraction of 29% and a mean QRSd of 168 ± 24 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LV electrical dyssynchrony than BVP (-10 ms; 95% CI: -16 to -4 ms; P = 0.001); the difference between LVSP and BVP was not significant (-5 ms; 95% CI: -12 to 1 ms; P = 0.10). LBBP was associated with higher systolic blood pressure than BVP (4%; 95% CI: 2%-5%; P < 0.001), whereas LVSP was not (1%; 95% CI: 0%-2%; P = 0.10). Hemodynamic differences during LBBP and LVSP vs BVP were more pronounced in nonischemic than ischemic patients. CONCLUSIONS: Ultra-high-frequency electrocardiography allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamic status as BVP, while LBBP was better than BVP in both.

• Keywords
• BVP, LBBP, LVSP, UHF-ECG, cardiac resynchronization therapy, dyssynchrony,
• MeSH
• Ventricular Dysfunction, Left physiopathology   therapy   MeSH
• Electrocardiography * MeSH
• Ventricular Function, Left physiology   MeSH
• Hemodynamics * physiology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Ventricular Septum physiopathology   MeSH
• Aged MeSH
• Cardiac Resynchronization Therapy * methods   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study 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

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

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

BACKGROUND: Right ventricular myocardial pacing leads to nonphysiological activation of heart ventricles. Contrary to this, His bundle pacing preserves their fast activation. Ultra-high-frequency electrocardiography (UHF-ECG) is a novel tool for ventricular depolarization assessment. OBJECTIVE: The purpose of this study was to describe UHF-ECG depolarization patterns during myocardial and His bundle pacing. METHODS: Forty-six patients undergoing His bundle pacing to treat bradycardia and spontaneous QRS complexes without bundle branch block were included. UHF-ECG recordings were performed during spontaneous rhythm, pure myocardial para-Hisian capture, and His bundle capture. QRS duration, QRS area, depolarization time in specific leads, and the UHF-ECG-derived ventricular dyssynchrony index were calculated. RESULTS: One hundred thirty-three UHF-ECG recordings were performed in 46 patients (44 spontaneous rhythm, 28 selective His bundle, 43 nonselective His bundle, and 18 myocardial capture). The mean QRS duration was 117 ms for spontaneous rhythm, 118 ms for selective, 135 ms for nonselective, and 166 ms for myocardial capture (P < .001 for nonselective and myocardial capture compared to each of the other types of ventricular activation). The calculated dyssynchrony index was shortest during spontaneous rhythm (12 ms; P = .02 compared to selective and P = .09 compared to nonselective), and it did not differ between selective and nonselective His bundle capture (16 vs 15 ms; P > .99) and was longest during myocardial capture of the para-Hisian area (37 ms; P < .001 compared to each of the other types of ventricular activation). CONCLUSION: In patients without bundle branch block, both types of His bundle, but not myocardial, capture preserve ventricular electrical synchrony as measured using UHF-ECG.

• Keywords
• Electrical dyssynchrony, His bundle, Myocardial, Pacing, Ultra-high-frequency ECG,
• MeSH
• Bundle-Branch Block physiopathology   therapy   MeSH
• Electrocardiography methods   MeSH
• Ventricular Function, Left physiology   MeSH
• Ventricular Function, Right physiology   MeSH
• Bundle of His physiopathology   MeSH
• Cardiac Pacing, Artificial methods   MeSH
• Humans MeSH
• Aged MeSH
• Heart Rate physiology   MeSH
• Heart Ventricles physiopathology   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

INTRODUCTION: The present study introduces a new ultra-high-frequency 14-lead electrocardiogram technique (UHF-ECG) for mapping ventricular depolarization patterns and calculation of novel dyssynchrony parameters that may improve the selection of patients and application of cardiac resynchronization therapy (CRT). METHODS: Components of the ECG in sixteen frequency bands within the 150 to 1000 Hz range were used to create ventricular depolarization maps. The maximum time difference between the UHF QRS complex centers of mass of leads V1 to V8 was defined as ventricular electrical dyssynchrony (e-DYS), and the duration at 50% of peak voltage amplitude in each lead was defined as the duration of local depolarization (Vd). Proof of principle measurements was performed in seven patients with left (left bundle branch block) and four patients with right bundle branch block (right bundle branch block) before and during CRT using biventricular and His-bundle pacing. RESULTS: The acquired activation maps reflect the activation sequence under the tested conditions. e-DYS decreased considerably more than QRS duration, during both biventricular pacing (-50% vs -8%) and His-bundle pacing (-77% vs -13%). While biventricular pacing slightly increased Vd, His-bundle pacing reduced Vd significantly (+11% vs -36%), indicating the contribution of the fast conduction system. Optimization of biventricular pacing by adjusting VV-interval showed a decrease of e-DYS from 102 to 36 ms with only a small Vd increase and QRS duration decrease. CONCLUSIONS: The UHF-ECG technique provides novel information about electrical activation of the ventricles from a standard ECG electrode setup, potentially improving the selection of patients for CRT and application of CRT.

• Keywords
• His-bundle pacing, biventricular pacing, cardiac resynchronization therapy, ultra-high-frequency ECG, ventricular electrical dyssynchrony,
• MeSH
• Action Potentials MeSH
• Bundle-Branch Block diagnosis   physiopathology   therapy   MeSH
• Time Factors MeSH
• Electrocardiography * MeSH
• Ventricular Function, Left MeSH
• Ventricular Function, Right MeSH
• Bundle of His physiopathology   MeSH
• Humans MeSH
• Proof of Concept Study MeSH
• Predictive Value of Tests MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Heart Rate * MeSH
• Cardiac Resynchronization Therapy * MeSH
• Heart Failure diagnosis   physiopathology   therapy   MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH