Nonselective His Bundle Pacing Research Articles

Temporal evolution of His bundle pacing thresholds: a sub-study of the PACE-CONDUCT trial

Abstract Background His bundle pacing (HBP) has become a valuable alternative for cardiac resynchronization therapy, offering physiological pacing. This substudy of the PACE-CONDUCT trial aimed to explore the influence selective and non-selective HBP on threshold height. We assessed these parameters in patients with both normal conduction and bundle branch block conduction. Methods Our study included 61 consecutive patients with a median age of 73 years, who underwent a successful HBP implantation for indications such as sick sinus syndrome, AV Block 2 type 2, binodal disease, and ablate and pace therapy prior to AV-node ablation. Among these patients, 18 exhibited QRS durations exceeding 150 ms, indicating a complete and broad bundle branch block which made them candidates for cardiac resynchronization therapy (CRT). All patients received HBP implantation with the assistance of a 3D electroanatomical system. This system allowed for low-fluoroscopic, atraumatic evaluation of the His bundle (HB) area, presenting the His voltage as a color-coded map for precise electrode placement. Results The feasibility of bundle branch correction is generally accepted in selective HBP distal to the site of block, albeit associated with higher threshold values and potentially lower battery duration. Our analysis encompassed 61 patients who underwent HBP implantation, with 23 patients (37,7%) exhibiting selective HBP and 38 (62,3%) non-selective HBP. Remarkably, 10 out of the 23 patients with selective HBP demonstrated a complete bundle branch block correction after HBP implantation even with a basal QRS durations exceeding 150 ms. We evaluated HBP thresholds at implantation, one day post-implantation, and one month post-implantation, correlating these data with selective and non-selective HBP. Threshold values were converted to volts per millisecond (volts × milliseconds) for analysis. Statistical analysis conducted with IBM SPSS 29.0 revealed a significant difference at the day of implantation, indicating higher threshold capture in selective HBP compared to non-selective HBP (one-sided p-value: < 0.01, two sided p value 0.01). However, this difference could not be sustained at the one-day and one-month threshold follow-ups, suggesting normalization of the selective HBP threshold. Conclusion In our study, the initially higher threshold in selective HBP normalized within 24 hours compared to non-selective HBP. Additionally, our study demonstrated the feasibility of selective His pacing in patients with complete bundle branch block and broad QRS durations. These findings provide insights into HBP optimization and encourage further investigations with larger patient cohorts to validate our observations and enhance patient care in the realm of cardiac pacing.Threshold trend

Single-center experience with His bundle lead implantation: success rate, implantation method optimization, and lessons learned in 426 patients

Abstract Background Conduction system pacing (CSP) is increasingly used to avoid the development of pacing-induced cardiomyopathy in patients who require a high amount of ventricular pacing. His bundle pacing (HBP) is considered as ideal to achieve the narrowest paced QRS and optimal synchronization in patients with intrinsic narrow QRS or right bundle branch block but also as difficult at implantation. Purpose We analyzed our experience with HBP in terms of time and effort, pacing and sensing results, success rate, and lessons learned for optimization over a time period of 7 years. Methods All consecutive patients in whom HBP was attempted between 6/2016 and 11/2023 were included in this analysis. Implantations were performed using a pacing system analyzer (PSA) with high-resolution electrograms (EGMs). Data on implantation success [selective or non-selective HBP, left bundle branch area pacing (LBBAP)], sensing and pacing parameters, achievement of His bundle current of injury (coi), duration of implantation and fluoroscopy were collected prospectively. These results were compared for the 1st, 2nd, 3rd and 4th quartile of implantations and reasons for improvement or deterioration were analyzed. Results HBP was attempted in 426 patients (78±11 years, 38% female, 90% AV block, left ventricular ejection fraction 54±10 %, 81 single-, 286 dual-, 46 triple-chamber pacemakers, 2 dual- and 11 triple-chamber ICDs) and was successful in 404 patients (95%): 182 non-selective HBP, 206 selective HBP, and 16 LBBAP. R wave amplitude was 4.5±3.5 mV, pacing threshold 1.1 ± 0.6V/1.0 ms. In 16% of patients, a ventricular back-up lead was implanted. A His bundle coi was achieved in 61% of patients. The implantation duration was 92±43 min, fluoroscopy duration 10±8 min. Success rate increased from 89% in the 1st to 99% in the 4th quartile. Improved implantation success was associated with using a stiff 3D steerable sheath, implantation site at the distal His bundle, and an increased number of screw-in turns until a His bundle coi was visible. Conclusions Establishing an implantation routine with 1) a PSA and high-resolution EGMs, 2) use of a stiff 3D steerable sheath, 3) implantation at the distal His bundle with myocardial capture (non-selective HBP) as a back-up, and 4) an increased number of screw-in turns of the lead tip until a His bundle coi is achieved, HBP implantation can be facilitated and results optimized to a highly acceptable implantation effort and a success rate >95%.

Development of chronic thresholds in His bundle pacing: single-center experience over 7 years in 426 patients

Abstract Background Conduction system pacing (CSP), e. g. by His bundle pacing (HBP) has the potential to perform highly synchronized ventricular pacing in patients with AV block and narrow QRS complex or right bundle branch block. Therefore, CSP is recommended in these patients to prevent pacing-induced cardioomyopathy. However, there have been reports about an acute and chronic threshold increase in HBP that may cause asystole in pacemaker-dependent patients. Purpose We checked the development of chronic pacing thresholds, the incidence of dislodgements and of consecutive asystole in patients with HBP. Methods All consecutive patients with HBP attempted in our center between 6/2016 and 11/2023 were enrolled. Pacing and sensing parameters over 36 months together with the follwing events were collected and analyzed: His bundle lead dislodgement, loss of capture, threshold increase to ≥3.0V/1.0 ms, emergency admission due to syncope with loss of HBP and asystole. Results In 426 patients (78±11 years, 38% female, 90% AV block, left ventricular ejection fraction 54±10%), HBP was attempted and in 388 patients successful (47% non-selective, 53% selective HBP), 16 patients were converted to left bundle branch area pacing, 22 implantations attemps were unsuccessful. Pacing and sensing performance during follow-up are listed in the Fig. There were 3 lead dislodgements (2 patients with Twiddler syndrome), 1 loss of capture (patient with sinus node disease), and 13 increases of pacing thresholds to ≥3.0V/1.0 ms, summing up to 17 events over 3 years (4.3%). No patient had a clinical event due to threshold increase or loss of HBP capture. All His bundle threshold increases were clinically silent because patients were not pacemaker-dependent, had non-selective HBP with myocardial capture serving as a "back-up" or due to a previously implanted right ventricular back-up lead. Conclusions There is a modest pacing threshold increase in His bundle thresholds from 1.1 to 1.8V@1.0 ms over a period of 3 years. However, this did not cause clinically relevant events in our patient cohort.Chronic pacing and sensing parameters

Left bundle branch pacing preserved left ventricular myocardial work in patients with bradycardia.

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. Left ventricular (LV) myocardial work (MW) incorporates afterload and LV global longitudinal strain to estimate global and segmental myocardial contractility. However, the effect of LBBP on LV MW remains unknown. This study aimed to evaluate the impact of LBBP on LV MW in patients receiving pacemaker for bradyarrhythmia. We prospectively enrolled 70 bradycardia patients with normal LV systolic function receiving LBBP (n = 46) and non-selective His-bundle pacing (NS-HBP) (n = 24). For comparative analysis, patients receiving right ventricular pacing (RVP) (n = 16) and control subjects (n = 10) were enrolled. Two-dimensional speckle tracking echocardiography was performed. The LV pressure-strain loop was non-invasively constructed to assess global LV MW. After 6-month follow-up, LBBP group (with >40% ventricular pacing during 6 months) had shorter peak strain dispersion (PSD) compared with RVP group, and higher LV global longitudinal strain compared with RVP group and NS-HBP group, but had no difference in left intraventricular mechanical dyssynchrony, including septal-to-posterior wall motion delay and PSD, compared with NS-HBP group. During ventricular pacing, LBBP group had higher global MW index (GWI) (2,189 ± 527 vs. 1,493 ± 799 mmHg%, P = 0.002), higher global constructive work (GCW) (2,921 ± 771 vs. 2,203 ± 866 mmHg%, P = 0.009), lower global wasted work (GWW) (211 ± 161 vs. 484 ± 281 mmHg%, P < 0.001) and higher global MW efficiency (GWE) (91.4 ± 5.0 vs. 80.9 ± 8.3%, P < 0.001) compared with RVP group, and had lower GWW (211 ± 161 vs. 406 ± 234 mmHg%, P < 0.001) and higher GWE (91.4 ± 5.0 vs. 86.4 ± 8.1%, P < 0.001) compared with NS-HBP group. In this study we found that in patients with mid-term (6-month) high ventricular pacing burden (>40%), LBBP preserved more LV MW compared with NS-HBP and RVP. Further studies are warranted to assess the association between LV MW and long-term clinical outcomes in LBBP with high ventricular pacing burden.

Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing.

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited. We included 152 consecutive patients (mean age 61±24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n=54), para-Hisian region (n=66), or mid interventricular septum (n=17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI). QRS duration was prolonged in all pacing sites: from 114±28 to 160±29 (RV apex), from 110±28 to 122±29 (para-Hisian), and from 121±24 to 154±30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48h after implantation but did not require repositioning. QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Conduction system pacing guided by 3d-electroanatomic mapping system preserves systolic function in paediatric patients

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Paediatric transvenous permanent pacing from alternative ventricular sites including conduction system pacing may prevent ventricular dyssynchrony and systolic dysfunction. These procedures may be difficult and require higher fluoroscopic exposures. The use of three-dimensional-electroanatomic mapping system (3D-EAM) may guide lead implantation toward these alternative sites and reduce fluoroscopic exposure. Purpose of this study is the outcome of 3D-EAM-guided alternative sites pacing in paediatric patients. Methods Retrospective analysis of children and young patients with congenital or acquired complete atrioventricular block (CAVB) with or without other congenital heart disease (CHD) who underwent 3D-EAM-guided transvenous pacing in alternative sites of the subpulmonary ventricle, to perform non-selective His bundle pacing (NSHBP), pacing of ventricular septum close to conduction system (VS-CSP) or outflow tract (OT). 3D-pacing map guided stylet-directed screw-in lead implantation toward septal sites with narrower paced QRS. Procedure and follow-up data were recorded. Parameters of ECG (QRS duration, left ventricular activation time, LVAT), echocardiogram (3D ejection fraction, EF, global longitudinal strain, GLS, of the systemic ventricle) and lead (threshold, sensing) were registered and compared at baseline (pre-implantation) and during follow-up (1-3-year). Data are reported as median (25th-75th centiles). P&amp;lt;0.05 was significant. Results 64 patients (47 females) with CAVB, of whom 11 with CHD, underwent 3D EAM-guided pacing (31 VVIR, 33 DDD) at age 12 (8-15) years, weight 44 (27-57) kg. Prior pacing (RV apex, RV and LV free wall, also biventricular) was present in 27 patients. Pacing sites were: 10 NSHBP, 5 RVOT, 49 VS-CSP (Figure 1). Procedure time was 175 (146-200) min, fluoroscopy exposure was: 3.0 (1.2-5.0) mGy and 90 (33-146) microGy/m2. Echographic parameters at baseline and follow-up are reported in Table 1. Baseline QRS duration 85 (80-130) ms, increased after implantation, 115 (100-120) ms (P=0.002), with LVAT 80 (70-81) ms (Figure 1). In patients with prior pacing, QRS shortened post-implantation: QRS 130 (120-160) vs. 120 (110-125)ms (P=0.004). Lead parameters were good post-implantation and at 3-year follow-up: threshold 0.5 (0.4-0.7) vs. 0.9 (0.7-1.2)V/0.5 ms; R-wave sensing 9 (6-12) vs. 7 (4-9)mV. Four NSHBP patients showed lead dislodgement requiring lead repositioning. Conclusions 3D-EAM-guided alternative site pacing was accomplished with low fluoroscopic exposure. Paced QRS duration was significantly broader than in junctional rhythm but it was significantly narrower than prior epi/conventional site endo pacing. This pacing approach preserved ventricular systolic function in paediatric patients with CAVB at mid-term follow-up.

Forecasting patient instability: Current advances & future opportunities

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited.We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI).QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning.QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Echocardiographic Evaluation of His Bundle Pacing in Patients with Prolonged PR Intervals.

Patients with PR intervals >240ms have atrio-ventricular (AV) dyssynchrony, which can increase risk of atrial fibrillation and all-cause mortality. When requiring pacing, long AV delays (AVDs) have been programmed to avoid ventricular dyssychrony. His bundle pacing (HBP) may provide improved AV synchrony in patients with prolonged PR. 10 patients with sinus node dysfunction and prolonged PR who received HBP were studied. Real-time echocardiographic was performed with 3 pacemaker modes (RV septal, non-selective HBP, and selective HBP) using the following pacemaker settings: control (no ventricular pacing), pacing with AVD of 180ms, 150ms, 120ms, 100ms, and 70ms. Echocardiographic Doppler measurements: EA/RR, >40% = AV synchrony; E/e', <8 = normal left atrial pressure; pulmonic-to-aortic pre-ejection time difference, <40ms = interventricular synchrony; septal-to-lateral wall activation time difference, <56ms = intraventricular synchrony; and LVOT VTI. Unpaired T test was used to evaluate for significance. Exclusion criteria: persistent atrial fibrillation, second-degree AV block. Compared to control programming, HBP showed a 31.5% increase in EA/RR time, a decrease in E/e' of 26.9%, and an increase in the LVOT VTI of 21.3%. Compared to RV septal pacing, there was a similar increase in LVOT VTI. These findings met statistical significance and were considered optimal based on Doppler echocardiography findings primarily at AVDs of 150ms and 120ms. Comparisons between selective and non-selective pacing were not significantly different. Compared to controls and RV septal pacing, physiologic His bundle pacing was shown to increase markers of AV synchrony and LV stroke volume while maintaining ventricular synchrony.

Results of Using Various Conduction System Pacing Options in Patients with Bradyarrhythmia

Chronic right ventricular myocardial pacing causes an asynchronous pattern of left ventricular activation, reduces left ventricular ejection fraction (LVEF), and may be associated with worsening of clinical outcomes in the long term. Although with the emergence of algorithms that minimize ventricular pacing it became possible to reduce the percentage of paced complexes in patients with sinus node dysfunction, permanent ventricular pacing is still inevitable in patients with high-degree atrioventricular (AV) block. The use of permanent conduction system pacing is a promising method for preserving the physiological activation of the ventricular myocardium and preventing the development of heart failure due to ventricular dyssynchrony.&#x0D; The aim. To analyze the immediate and long-term results of the use of conduction system pacing in patients with indications for permanent ventricular pacing.&#x0D; Materials and methods. This study included 18 patients with indications for permanentventricular pacing who were operated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine in the period from 01/01/2013 to 12/31/2022, in whom permanent conduction system pacing was used. There were 17 patients with bradyarrhythmias, of these 16 (88%) suffered from high-degree AV block (including 1 patient with Frederick’s syndrome and 1 (5%) patient with atrial ϐibrillation with slow ventricular response) and 1 (5%) patient with ischemic cardiomyopathy with left bundle branch block and ϐirstdegree AV block with indications for cardiac resynchronization therapy. The mean age of the patients was 55 ± 16 years (8 men, 10 women), LVEF at the time of the intervention was 56.42 ± 9.13 %, end diastolic volume 130.2 ± 23.8 ml, end systolic volume 55.1 ± 17.7 ml, diameter of the left atrium 4.01 ± 0.6 cm. The average QRS width before implantation was 116.5 ± 27.7 ms. In 6 (33%) patients, a special delivery system (С304-L69, Medtronic in 1 patient [5%], C315HIS in 5 [27%] patients) and 4.1F active ϐixation lead Medtronic 3830 Select Secure (69 or 74 cm) were used; in other cases (66%) standard 6F leads with active ϐixation and a lumen for a stylet without a delivery system were used.&#x0D; Results. The average follow-up period after implantation of pacemaker was 36.35 ± 29.65 months. During the observation period, LVEF was 57.07 ± 5.38 %, end diastolic volume111.5 ± 18.09 ml, end systolic volume 49.5 ± 13.4 ml, diameter of the left ventricle 3.9 ± 0.5 cm. The mean duration of paced QRS was 119.1 ± 10.09 ms. In 6 patients (33%), it was possible to demonstrate a change in the QRS width when the amplitude of ventricular stimulation was reduced, with 2 variants of transitions: 1) 4 (22%) patients with a transition from non-selective His bundle pacing (NSHBP) to selective His bundle pacing (SHBP), in 2 (11%) of these patients with a transition from SHBP with correction of right bundle branch block (RBBB) to SHBP without correction of RBBB, and then loss of capture of the myocardium of the ventricles; 2) 2 patients (11%) with a transition from NSHBP to myocardial septal ventricular pacing and further with a decrease in amplitude to the loss of capture of the myocardium of the ventricles. One (5%) patient with complete heart block had permanent non-selective left bundle branch area pacing. The other 11 (61%) patients met the criteria for parahisian pacing without visible transitions with a change in the amplitude of ventricular pacing. The average global longitudinal strain was -17.6 ± 2.7 %. The average interval from the stimulus to the peak of the R-wave in lead V6, which indicated the time of left ventricular activation, was 73.2 ± 8.7 ms. Pacing parameters were standardly set according to the primary indications, but with correction of the amplitude of ventricular stimulation relative to the thresholds of pacing of the conduction system. AV delay was corrected for the latency from the stimulus to the onset of the QRS in SHBP or for the duration of the “pseudodelta” wave in NSHBP which in both cases was the duration of the H-V interval. There were no complications in the acute or long-term postoperative period.&#x0D; Conclusions. Conduction system pacing is a challenge in the practice of cardiologist for treating life-threatening bradyarrhythmias and heart failure, but at the same time it is a safe method that provides physiological electrical and mechanical activation of the myocardium of the ventricles, that allows to effectively avoid the consequences of dyssynchrony due to permanent myocardial ventricular pacing.

Physiological vs. non-physiological heart pacing as assessed by ultra-high-frequency ECG

Abstract Background The dyssynchrony related to permanent cardiac pacing is the main reason for heart failure in some patients. Physiological pacing techniques as His bundle pacing (HBP), left bundle branch pacing (LBBP), and left ventricular myocardial septal pacing (LVSP) were shown to improve clinical outcomes in patients with pacemakers. Due to specific lead placement in the area close to conductive tissue, several different ventricular capture types are possible during them. Method We studied the effect of these pacing modalities on ventricular synchrony using ultra-high-frequency ECG (UHF-ECG), which is a novel tool for ventricular depolarization visualization. Several parameters of dyssynchrony were calculated and compared between studied ventricular capture types. Results We showed ventricular depolarization during nonselective HBP to be equivalent to selective HB pacing. Next, we demonstrated the nonselective HBP in the area below the tricuspid valve leads to the best interventricular synchrony from all other RV pacing locations. We also compared UHF-ECG-derived parameters of ventricular depolarization during HBP, LBBP, and LVSP, and we showed that both pacing types from the left septal area are less physiological than HBP. nsLBBP and sLBBP deteriorate interventricular dyssynchrony, and LVSP leads to less physiological left ventricular depolarization than HBP. Conclusion UHF-ECG is an effective tool that can be used in clinical practice to assess the electrical dyssynchrony caused by cardiac pacing. Furthermore, its real-time implementation allows recognizing between physiological vs. non-physiological pacing during an implant procedure. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic

Non Selective his Bundle Pacing: As Physiological as S-HBP but Simpler and Faster

We have read with interest Dr. Burri’s Electrocardiographic Analysis for His Bundle Pacing at Implantation and Follow up [1]. A comprehensive guide to understand electrocardiographic (ECG) nuances of His Bundle Pacing (HBP) is presented in this review. The authors, with outstanding didactics, describe a well-organized analysis of challenging HBP electrocardiographic characteristics to confirm conduction tissue (selective or non-selective HBP) at implant and follow-up. Caught our interest, in particular, the paragraph where practical pacing characteristics and benefits of non-selective HBP pacing (NSHBP) are emphasized. In this context we would like to point out the statement that pacing “ventricular myocardium adjacent to the atrioventricular septum, near the His bundle can also result in NSHBP”. Above all, of paramount clinical importance, when Dr. Burri et al. conclude that “No significant differences in cardiac mechanical synchrony or clinical outcome have been found between SHBP and NSHBP”. Our group is in total agreement with these essential features, having abandoned SHBP many years ago by developing a very simple technique to place standard pacing leads in the para-Hisian area (Figure 1). Concordant with the authors, we understand that “With non-selective His bundle pacing (NS-HBP), the lead is usually positioned in the ventricle at a site where the His bundle (HB) is surrounded by or at proximity to myocardial tissue”. That is why we named “para-Hisian pacing”. In our daily practice, at the same time, to verify and prove physiological capture of the conduction system we monitor synchrony online by analyzing the ECG signal variance [8] (Synchromax®) [2].

His bundle pacing guided by automated intrinsic morphology matching is feasible in patients with narrow QRS complexes

Pace mapping and visual comparison of the local pacing response with the intrinsic QRS morphology form the mainstay of His bundle pacing (HBP). We evaluated the performance of a surface lead morphology match algorithm for automated classification of the pacing response in patients with narrow intrinsic QRS undergoing electroanatomic mapping (EAM)-guided HBP. HBP was attempted in 43 patients. In 28 cases with narrow QRS, the EnSite AutoMap Module was used for automated assessment of the QRS morphology resulting from pace mapping in the His cloud area with either a diagnostic catheter or the His lead. An intrinsic morphology match score (IMS) was calculated for 1.546 QRS complexes and assessed regarding its accuracy and performance in classifying the individual pacing response as either selective HBP (S-HBP), nonselective HBP (NS-HBP) or right ventricular stimulation. Automated morphology comparison of 354 intrinsic beats with the individual reference determined a test accuracy of 99% (95% CI 98.96–99.04) and a precision of 97.99–99.5%. For His-lead stimulation, an IMS ≥ 89% identified S-HBP with a sensitivity, specificity and positive predictive value of 1.00 (0.99, 1.00) and a negative predictive value of 0.99 (0.98, 1.00). An IMS between 78 and < 89% indicated NS-HBP with a sensitivity and specificity of 1.00 (0.99, 1.00) and 0.99 (0.98, 1.00), respectively. IMS represents a new automated measure for standardized individual morphology classification in patients with normal QRS undergoing EAM-guided HBP.Clinical trial registration: NCT04416958.

Can permanent His Bundle Pacing be safely started by operators new to this technique? Data from a multicenter registry

Right ventricular pacing (RVP) induces ventricular asynchrony in patients with normal QRS and increases the risk of heart failure and atrial fibrillation on long-term. His bundle pacing (HBP) is a physiological alternative to RVP, and could overcome its drawbacks. Recent studies assessed feasibility and safety of HBP in expert centers with a vast experience of this technique. These results may not apply to less experienced centers. We aim to evaluate feasibility and safety of permanent HBP performed by physicians who are new to this technique. We included all patients who underwent pacemaker implantation with attempt of HBP in 3 hospitals between September 2017 and January 2020. Indication for HBP was left to operators’ discretion. All the operators were new for HBP. His Bundle (HB) electrical parameters were recorded at implant, 3- and 12-month follow-up. HBP was successful in 141 of 170 patients (82.9%); selective HBP was obtained in 96 patients and nonselective HBP in 45. The mean procedure and fluoroscopy durations were 67.0 ± 28.8 min, and 7.3 ± 8.1 min (3.1 ± 4.1 Gy.cm 2 ), respectively. The mean HB paced QRS duration was 106 ± 18 ms. The mean HB capture threshold was 1.29 ± 0.77 V and did not increase at 3- and 12-month follow-up. Ventricular lead revision was required in 5 patients. Our results showed a rapid technical learning allowing a high procedure success rate (89.8%) after 15 procedures ( Fig. 1 ). HBP performed by operators new to this technique appeared feasible and safe. This should encourage HBP to be performed in patients expected to experience high RVP burden.

Evidence of Fasciculoventricular Pathway Activation in Non-Selective His-Bundle Pacing: A Double-Blind Comparison of 12-Lead Electrocardiograms

Evidence of Fasciculoventricular Pathway Activation in Non-Selective His-Bundle Pacing: A Double-Blind Comparison of 12-Lead Electrocardiograms

Effect of Nonselective His Bundle Pacing on Delayed Myocardial Activation in Left-axis Deviation and Left Bundle Branch Block.

It has been suggested that nonselective His bundle pacing (NS-HBP) corrects terminal conduction delay in right bundle branch block by early excitation of the right ventricular free wall. A similar analysis of NS-HBP, in patients with left bundle branch block (LBBB) and left-axis deviation (LAD) has not been done. Therefore, we compared the baseline QRS parameters in LAD and LBBB during NS-HBP and selective HBP (S-HBP). In LAD patients (n = 16), NS-HBP normalized the QRS axis from −35° ± 10° to 30° ± 34° (p < 0.01) and increased the lead 1 voltage (L1V) from 0.55 ± 0.3 mV to 0.88 ± 0.2 mV (p < 0.001) without increasing the peak lateral wall activation time (PLWAT) (p = not significant). In 23 of 41 LBBB patients, NS-HBP decreased the prolonged PLWAT by 73 ms (p < 0.0001), resolved the mid-QRS notch, normalized the QRS axis, and increased the L1V from 0.5 ± 0.3 mV to 1.15 ± 0.3 mV (p < 0.0001). In the remaining 18 LBBB patients, NS-HBP did not resolve the mid-QRS notch; however, the peak septal activation time decreased by 45 ms (p < 0.0001), PLWAT decreased by 53 ms (p < 0.0001), L1V increased from 0.5 ± 0.3 mV to 0.87 ± 0.4 mV (p < 0.0001), and the QRS axis normalized. All patients who developed S-HBP at lower pacing showed uncorrected LBBB (n = 6) or LAD (n = 7). In conclusion, NS-HBP, which causes myocardial activation in advance of simultaneously initiated S-HBP, results in a paced QRS complex with a normal axis and shorter activation times and restores the L1V in patients with LAD and LBBB. In some patients, a mid-QRS notch was seen with NS-HBP, which suggests fusion with S-HBP, which conducts without LBBB correction. A higher L1V in association with a shorter PLWAT and a normal QRS axis suggests that a more organized degree of left ventricular activation occurs with NS-HBP as compared to LBBB.

Can permanent His bundle pacing be safely started by operators new to this technique? Data from a multicenter registry

Right ventricular pacing (RVP) induces ventricular asynchrony in patients with normal QRS and increases the risk of heart failure and atrial fibrillation in long-term. His bundle pacing (HBP) is a physiological alternative to RVP, and could overcome its drawbacks. Recent studies assessed the feasibility and safety of HBP in expert centers with a vast experience of this technique. These results may not apply to less experienced centers. We aim to evaluate the feasibility and safety of permanent HBP performed by physicians who are new to this technique. We included all patients who underwent pacemaker implantation with attempt of HBP in three hospitals between September 2017 and January 2020. Indication for HBP was left to operators’ discretion. All the operators were new for HBP. His bundle (HB) electrical parameters were recorded at implant, 3- and 12-month follow-up. HBP was successful in 141 of 170 patients (82.9%); selective HBP was obtained in 96 patients and nonselective HBP in 45. The mean procedure and fluoroscopy durations were 67.0 ± 28.8 min, and 7.3 ± 8.1 min (3.1 ± 4.1 Gy·cm 2 ), respectively. The mean HB paced QRS duration was 106 ± 18 ms. The mean HB capture threshold was 1.29 ± 0.77 V and did not increase at 3- and 12-month follow-up. The ventricular lead revision was required in five patients. Our results showed a rapid technical learning allowing a high procedure success rate (89.8%) after 15 procedures ( Fig. 1 ). HBP performed by operators new to this technique appeared feasible and safe. This should encourage HBP to be performed in patients expected to experience high RVP burden.

Left bundle branch pacing compared to left ventricular septal myocardial pacing increases interventricular dyssynchrony but accelerates left ventricular lateral wall depolarization

Nonselective His-bundle pacing (nsHBp), nonselective left bundle branch pacing (nsLBBp), and left ventricular septal myocardial pacing (LVSP) are recognized as physiological pacing techniques. The purpose of this study was to compare differences in ventricular depolarization between these techniques using ultra-high-frequency electrocardiography (UHF-ECG). In patients with bradycardia, nsHBp, nsLBBp (confirmed concomitant left bundle branch [LBB] and myocardial capture), and LVSP (pacing in left ventricular [LV] septal position without proven LBB capture) were performed. Timings of ventricular activations in precordial leads were displayed using UHF-ECG, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. Duration of local depolarization (Vd) was determined as width of the UHF-QRS complex at 50% of its amplitude. In 68 patients, data were collected during nsLBBp (35), LVSP (96), and nsHBp (55). nsLBBp resulted in larger e-DYS than did LVSP and nsHBp [- 24 ms (-28;-19) vs -12 ms (-16;-9) vs 10 ms (7;14), respectively; P <.001]. nsLBBp produced similar values of Vd in leads V5-V8 (36-43 ms vs 38-43 ms; P = NS in all leads) but longer Vd in leads V1-V4 (47-59 ms vs 41-44 ms; P <.05) as nsHBp. LVSP caused prolonged Vd in leads V1-V8 compared to nsHBp and longer Vd in leads V5-V8 compared to nsLBBp (44-51 ms vs 36-43 ms; P <.05) regardless of R-wave peak time in lead V5 or QRS morphology in lead V1 present during LVSP. nslbbp preserves physiological LV depolarization but increases interventricular electrical dyssynchrony. LV lateral wall depolarization during LVSP is prolonged, but interventricular synchrony is preserved.

Physiological Pacing: A New Road to Future

Anatomy and physiology are the basis of human body functioning and as we have progressed in management of various diseases, we have understood that physiological intervention is always better than an anatomical one. For more than 50 years, a standard approach to permanent cardiac pacing has been an anatomical placement of transvenous pacing lead at the right ventricular apex with a proven benefit of restoring the rhythm. However, the resultant ventricular dyssynchrony on the long-term follow-up in patients requiring more than 40% ventricular pacing led to untoward side effects in the form of heart failure and arrhythmias. To counter such adverse side effects, a need for physiological cardiac pacing wherein the electrical impulse be transmitted directly through the normal conduction system was sought. His bundle pacing (HBP) with an intriguing alternative of left bundle branch pacing (LBBP) is aimed at restoring such physiological activation of ventricles. HBP is safe, efficacious, and feasible; however, localization and placement of a pacing lead at the His bundle is challenging with existing transvenous systems due to its small anatomic size, surrounding fibrous tissue, long-learning curve, and the concern remains about lead dislodgement and progressive electrical block distal to the HBP lead. In this article, we aim to take the reader through the challenging journey of HBP with focus upon the hardware and technique, selective versus nonselective HBP, indications and potential disadvantages, and finally the future prospects.

Can permanent His bundle pacing be safely started by operators new to this technique? Data from a multicenter registry.

Right ventricular pacing (RVP) induces ventricular asynchrony in patients with normal QRS and increases the risk of heart failure and atrial fibrillation in long term. His bundle pacing (HBP) is a physiological alternative to RVP, and could overcome its drawbacks. Recent studies assessed the feasibility and safety of HBP in expert centers with a vast experience of this technique. These results may not apply to less experienced centers. We aim to evaluate the feasibility and safety of permanent HBP performed by physicians who are new to this technique. We included all patients who underwent pacemaker implantation with attempt of HBP in three hospitals between September 2017 and January 2020. Indication for HBP was left to operators' discretion. All the operators were new for HBP. His bundle (HB) electrical parameters were recorded at implant, 3- and 12-month follow-up. HBP was successful in 141 of 170 patients (82.9%); selective HBP was obtained in 96 patients and nonselective HBP in 45. The mean procedure and fluoroscopy durations were 67.0 ± 28.8 min, and 7.3 ± 8.1 min (3.1 ± 4.1 Gy·cm2 ), respectively. The mean HB paced QRS duration was 106 ± 18 ms. The mean HB capture threshold was 1.29 ± 0.77 V and did not increase at 3- and 12-month follow-up. The ventricular lead revision was required in five patients. Our results showed a rapid technical learning allowing a high procedure success rate (89.8%) after 15 procedures. HBP performed by operators new to this technique appeared feasible and safe. This should encourage HBP to be performed in patients expected to experience high RVP burden.

Permanent His bundle pacing can be safely started in centres with lack of experience of this technique: Results from a French multicentric registry

Right ventricular pacing (RVP) induces ventricular asynchrony in patients with normal QRS and increases the long term risk of heart failure and atrial fibrillation. His bundle pacing (HBP) is a physiological alternative to RVP. Interest in HBP has been hampered by technical challenges and limited implantation tool set. Recent studies assessed feasibility and safety of HBP in expert centres. These results may not apply to less experienced centres. To evaluate feasibility and safety of permanent His bundle pacing in hospitals with limited technical training to this technique and to evaluate stability of His Bundle capture (HBC) thresholds. We included all patients who underwent pacemaker implantation with attempt of HBP in 3 hospitals between September 2017 and December 2019. All the 6 operators were novice for HBP. HPB was successful in 134 of 154 patients (87.0%); selective HBP was obtained in 93 patients while non-selective HBP occurred in 41 patients. Indication for pacemaker implantation was AV conduction disease in 74 patients (48%), sinus node dysfunction in 30 patients (19.5%) and AV nodal ablation for non-controlled atrial arrhythmias in 50 (32.5%). The mean procedure duration was 68.2 ± 30.2 min, and the mean fluoroscopy duration was 7.5 ± 8.5 min (3.06 ± 1.01 Gy.cm 2 ). The mean HBC threshold was 1.28 ± 0.84V@0.5ms and did not increase at 3 months (1.26 ± 0.88V@0.5ms) and 12 months (1.25 ± 0.79V@0.5ms) follow-up. Ventricular lead revision was required at 3 months in two patients for sudden threshold increase without obvious lead dislodgement and at one month in one patient for lead dislodgement. There was no pericardial effusion, no pneumothorax and no device infection ( Fig. 1 ). His Bundle pacing performed by novice operators to this technique appeared feasible and safe. The mean HBC threshold did not increase at 3 months and one-year follow-up.