Mechanical Synchrony Research Articles

Evaluation of electrophysiological characteristics and ventricular synchrony: An intrapatient-controlled study during His-Purkinje conduction system pacingversus right ventricular pacing.

Objectives to BackgroundTo compare electromechanical ventricular synchrony when pacing from different sites, including right ventricular apex pacing (RVAP), right ventricular septum pacing (RVSP), His bundle pacing (HBP), left bundle branch pacing (LBBP), and RVSP during unipolar pacing from the ring electrode of LBBP lead (RVSPring) in each patient and evaluate the correlations between electrophysiological characteristics and ventricular synchrony.MethodsTwenty patients with complete atrioventricular block indicated for dual‐chamber pacemaker implantation were included in the study. Unipolar pacing at different sites, including RVAP, RVSP, HBP, LBBP, and RVSPring, was successively performed in each patient. The pacing characteristics and echocardiogram parameters were collected and compared among intrinsic rhythm and pacing at different sites.ResultsSimilar to HBP (114.84 ± 18.67 ms), narrower paced QRSd was found in LBBP (116.15 ± 11.60 ms) as compared to RVSPring (135.11 ± 13.68 ms), RVSP (141.65 ± 14.26 ms), and RVAP (160.15 ± 19.35 ms) (p < .001). LBBP showed comparable pacing parameters to RVAP or RVSP and was significantly better than HBP, with maintained cardiac function. TS‐12‐SD was significantly improved in LBBP (41.80 ± 20.97 ms) than RVAP (69.70 ± 32.42 ms, p = .003) and RVSP (63.30.56 ± 32.53 ms, p = .018) but similar to HBP (51.50 ± 25.67 ms, p = .283) or RVSPring (57.80 ± 25.65 ms, p = .198). Among these pacing strategies, negative values of interventricular mechanical delay (IVMD) were only identified in LBBP (−19.25 ± 18.43 ms), significantly different from RVAP (35.00 ± 30.72 ms), RVSP (22.85 ± 22.05 ms), HBP (5.20 ± 18.64 ms), and RVSPring (16.00 ± 26.76 ms (all p < .05). Using Pearson's analysis, Sti‐LVAT was positively correlated with QRS duration, IVMD, TS‐12‐SD, LVEDV, and LVESV, while a negative relationship could be observed for left ventricular ejection fraction.ConclusionsHis‐Purkinje conduction system pacing (HPCSP) achieved better electrical and mechanical synchrony than conventional RV pacing. For interventricular synchrony, only LBBP initiated earlier LV activation than RV, in accordance with the right bundle branch block (RBBB) pattern of paced QRS during LBBP. Sti‐LVAT might be a good parameter correlating with LV systolic function and mechanical synchrony.

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].

Transventricular Left Bundle Branch Pacing

Background. Implementation of conduction system permanent pacing methods in patients with cardiac bradyarrhythmias allows to maintain the physiological sequence of excitation and contraction of the ventricles and to avoid the development of heart failure due to electrical and mechanical dyssynchrony in patients with high rates of ventricular pacing.&#x0D; Case description. A 61-year-old female patient was examined and treated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine from January 25 to January 27, 2022 at the department of surgical treatment of complex cardiac arrhythmias with a diagnosis of proximal complete atrioventricular block. A two-chamber pacemaker (Vitatron Q50A2) with a ventricular lead to stimulate the His bundle region (Medtronic 3830, 69 cm) was implanted to the patient with a special delivery system (C315HIS). At an X-ray operating room, 12 ECG leads from the electrophysiological station LabSystem Pro (Bard, USA) were connected to the patient to analyze the criteria for capturing the conduction system on stimulation during ventricular lead placement, and a diagnostic quadripolar electrode was inserted into the right ventricle to record the potential of the His bundle as an X-ray reference point. During placement of the ventricular lead in the area of the His bundle due to high pacing thresholds the decision was made to implement an alternative method of conduction system pacing – left bundle branch pacing through the interventricular septum. After gradual passage of the electrode through the septum, capture of the conduction system of the heart was achieved, although no clear potential of the left bundle was registered. The interval from stimulus to peak R wave in lead V6 was 68 ms, and the interval from stimulus to peak R wave in lead V1 was 110 ms. The difference between intervals was 42 ms, which indicated the criteria of nonselective capture of the left bundle branch, with stimulation thresholds below 1 V at a pulse length of 0.5 ms. In the postoperative period, the patient was evaluated for global longitudinal deformity of the left ventricle on constant ventricular stimulation, which was carried out according to standard methods using speckle-tracking echocardiography; no signs of dyssynchrony were found. Also, the location of the endocardial electrode in the middle segments of the interventricular septum on the right ventricular side was visualized and confirmed by performing B-mode transthoracic echocardiography with subcostal access.&#x0D; Conclusions. Left bundle branch pacing, like His bundle pacing, maintains electrical and mechanical synchrony of the left ventricle at lower pacing thresholds, greater amplitude of the sensitivity signal and lower risks of lead dislocation.

Evaluation of clinical safety and efficacy of left bundle branch area pacing in comparison with right ventricular septal pacing.

Left bundle branch area pacing (LBBaP) has recently emerged as a new physiological pacing strategy. The purpose of this study is to compare LBBaP with right ventricular sepal pacing (RVSP) in terms of their clinical safety and efficacy.From February 2019 to May 2020, consecutive pacing-indicated patients were prospectively enrolled and divided into 2 groups. Ventricular synchrony indexes such as QRS duration (QRSd), interventricular mechanical delay and septal-posterior wall motion delay, left ventricular function such as left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF), pacing parameters, and complications were evaluated in the perioperative period and during follow-up.LBBaP was successful in 45 patients (88.2%), and finally 46 patients underwent RVSP. With LBBaP, ventricular electricalmechanical synchrony were similar to those of native-conduction system (P = .78). However, the ventricular electrical synchrony (QRSd, 108.47±7.64 vs 130.63±13.63ms, P < .001) and mechanical synchrony (interventricular mechanical delay, 27.68±4.33 vs 39.88±5.83, P < .001; septal-posterior wall motion delay, 40.39±23.21 vs 96.36±11.55, P < .001) in the LBBaP group were significantly better than those in the RVSP group. No significant differences in LVEDD (46 [44-48.5] vs 47 [44-52] mm, P = .49) and LVEF% (66 [62.5-70] vs 64 [61-68], P = .76) was observed between 2 groups at last follow-up. But, in the subgroup analysis, LVEDD was shorter (46 [44-49] vs 50 [47-58] mm, P = .03) and the LVEF% was higher (65 [62-68] vs 63 [58-65], P = .02) in the LBBaP-H (high ventricular pacing ratio >40%) group compared with RVSP-H group at last follow-up. There were lower capture thresholds (0.59±0.18V vs 0.71 ± 0.26 V, P = 0.01) at implantation in the LBBaP group than those in the RVSP group, with R-wave amplitudes and pacing impedances showing no significant difference between 2 groups. No serious complications were found in both 2 groups at implantation and follow-ups.This study confirms the clinical safety and efficacy of LBBaP, and it produces better ventricular electrical-mechanical synchrony than RVSP. The event of pacing-induced left ventricular dysfunction is lower in the LBBaP-H group than RVSP-H group.

Pacing-Induced Cardiomyopathy.

Right ventricular (RV) pacing-induced cardiomyopathy (PICM) is typically defined as left ventricular systolic dysfunction resulting from electrical and mechanical dyssynchrony caused by RV pacing. RV PICM is common, occurring in 10-20% of individuals exposed to frequent RV pacing. Multiple risk factors for PICM have been identified, including male sex, wider native and paced QRS durations, and higher RV pacing percentage, but the ability to predict which individuals will develop PICM remains modest. Biventricular and conduction system pacing, which better preserve electrical and mechanical synchrony, typically prevent the development of PICM and reverse left ventricular systolic dysfunction after PICM has occurred.

Electro-energetics of Biventricular, Septal and Conduction System Pacing.

Abnormal electrical activation of the ventricles creates abnormalities in cardiac mechanics. Local contraction patterns, as reflected by strain, are not only out of phase, but also show opposing length changes in early and late activated regions. Consequently, the efficiency of cardiac pump function (the amount of stroke work generated by a unit of oxygen consumed), is approximately 30% lower in dyssynchronous than in synchronous hearts. Maintaining good cardiac efficiency appears important for long-term outcomes. Biventricular, left ventricular septal, His bundle and left bundle branch pacing may minimise the amount of pacing-induced dyssynchrony and efficiency loss when compared to conventional right ventricular pacing. An extensive animal study indicates maintenance of mechanical synchrony and efficiency during left ventricular septal pacing and data from a few clinical studies support the idea that this is also the case for left bundle branch pacing and His bundle pacing. This review discusses electro-mechanics and mechano-energetics under the various paced conditions and provides suggestions for future research.

Abstract 13774: Comparison of His Bundle Pacing and Bi-Ventricular Pacing in Heart Failure Patients With Atrial Fibrillation Who Need Atrial-Ventricular Node Ablation: The ALTERNATIVE Study

Introduction: Cardiac resynchronization therapy typically is attempted with biventricular pacing (BVP). As an alternative to BVP, his bundle pacing (HBP) can maintain electrical and mechanical synchrony in patients with atrial fibrillation (AF) and atrioventricular node ablation (AVNA). However, there is still a lack of prospective randomized studies to compare BVP and HBP. Hypothesis: For patients with heart failure (HF) and AF who need AVNA, HBP is not inferior to traditional BVP. Methods: ALTERNATIVE is a prospective multicenter randomized single blind crossover study. Fifty consecutive AF patients who received BVP or HBP in conjunction with AVNA between March 2016 and February 2019 were enrolled in 6 centers. Patients were implanted with a right apical pacing lead, left ventricular lead, and HBP lead. After successful implant, patients were randomized in single patient-blinded fashion to either HBP or BVP. After 9 months, patients were crossed over to the other pacing modality and followed for another 9 months. Pacing parameters, echocardiographic measurements were obtained at baseline and at each follow-up. Results: Fifty patients were enrolled from 6 centers in this study. 25 received BVP and 25 HBP at first stage. Thirty-eight patients completed the crossover analysis at 18 months. LVEF were significantly improved for both pacing modes compared with baseline (30.93±7.27% vs. 51.29±10.79%, p&lt;0.001 in HBP; 33.43±9.40% vs. 51.94±10.97%, p&lt;0.001 in BVP). HBP was superior to BVP in terms of post-implant QRS duration (103.33±12.00 ms vs. 132.42±15.25 ms). Moreover, HBP can lead to greater improvement in cardiac function than BVP (p&lt;0.001 in LVEDd; p&lt;0.001 in LVEF). Conclusions: HBP can be used as a favorable alternative to BVP in patients with HF and AF after AVNA whose QRS complex is less than 120 ms. Further long-term and large studies are warranted to compare the outcomes between HBP and BVP.

Abstract 11164: Better Electromechanical Synchrony During Left Bundle Branch Pacing and His Bundle Pacing as Compared to Right Ventricular Pacing in Atrioventricular Block

Objectives: To compare electromechanical ventricular synchrony when pacing from different sites including right ventricular apex pacing (RVAP), right ventricular septum pacing (RVSP), His Bundle pacing (HBP), left bundle branch pacing (LBBP) and RVSP during unipolar pacing from the ring electrode of LBBP lead (RVSP ring ) in each patient during implantation. Methods: Twenty patients with complete atrioventricular block (AVB) indicated for dual-chamber pacemaker implantation were included. Unipolar pacing at different sites including RVAP,RVSP,HBP,LBBP and RVSP ring were successively performed in each patient while pacing characteristics and echocardiogram parameters were collected and compared. Results: Similar to HBP, narrower paced QRSd was found in LBBP as compared to RVSP ring , RVSP and RVAP(p&lt;0.001). LBBP showed comparable pacing parameters to RVAP or RVSP and were significantly better than HBP, with maintained cardiac function. For ventricular mechanical synchrony, TS-12-SD was significantly improved in LBBP(27.00±21.53ms) than RVAP(54.05±34.21ms, p=0.004) and RVSP(47.56±33.26ms, p=0.029) but similar to HBP or RVSP ring . Among these pacing strategies, negative values of interventricular mechanical delay(IVMD) were only identified in LBBP(-20.16±18.47ms), significantly different from RVAP(33.68±30.98ms), RVSP (21.68±22.02ms), HBP (4.74±19.04ms) and RVSP ring (14.56±26.76ms(all p&lt;0.001). Using Pearson’s analysis, Sti-LVAT was found to be positively corelated with QRS, IVMD, TS-12-SD, LVEDV and LVESV while a negative relationship could be observed for LVEF. Conclusions: Similar to HBP, LBBP achieved better electrical and mechanical left ventricular synchrony than conventional RV pacing. For interventricular synchrony, only LBBP initiated earlier LV activation than RV among these pacing strategies, in consistent with the RBBB pattern of paced QRS during LBBP.

Comparison of the Acute Effects of Different Pacing Sites on Cardiac Synchrony and Contraction Using Speckle-Tracking Echocardiography.

Background: Cardiac pacing in patients with bradyarrhythmia may employ variable pacing sites, which may have different effects on cardiac function. Left bundle branch pacing (LBBP) is a new physiological pacing modality, and the acute outcomes on cardiac mechanical synchrony during LBBP remain uncertain. We evaluated the acute effects of four pacing sites on cardiac synchrony and contraction using speckle-tracking echocardiography, and comparisons among four different pacing sites were rare.Methods: We enrolled 21 patients with atrioventricular block or sick sinus syndrome who each sequentially underwent acute pacing protocols, including right ventricular apical pacing (RVAP), right ventricular outflow tract pacing (RVOP), His bundle pacing (HBP), and left bundle branch pacing (LBBP). Electrocardiograms and echocardiograms were recorded at baseline and during pacing. The interventricular mechanical delay (IVMD), the standard deviation of the times to longitudinal peak strain during 17 segments (PSD), and the Yu index were used to evaluate ventricular mechanical synchrony. Layer-specific strain was computed using two-dimensional speckle tracking technique to provide in-depth details about ventricular synchrony and function.Results: Left ventricular ejection fraction (LVEF) and tricuspid annulus plane systolic excursion (TAPSE) were significantly decreased during RVAP and RVOP but were not significantly different during HBP and LBBP compared with baseline. RVAP and RVOP significantly prolonged QRS duration, whereas HBP and LBBP showed non-significant effects. IVMD and PSD were significantly increased during RVAP but were not significantly different during RVOP, HBP, or LBBP. LBBP resulted in a significant improvement in the IVMD and Yu index compared with RVAP. No significant differences in mechanical synchrony were found between HBP and LBBP.Conclusion: Among these pacing modalities, RVAP has a negative acute impact on cardiac synchrony and contraction. HBP and LBBP best preserve physiological cardiac synchrony and function.

Importance of frame rate for the measurement of strain and synchrony in fetuses using speckle tracking echocardiography.

To assess the influence of frame rate settings on longitudinal strain (LS) and mechanical synchrony (SYN) values in Speckle Tracking Echocardiography (STE) of healthy fetuses. In this prospective study, we collected transversal or apical four-chamber-views of 121 healthy fetuses between 20 and 38weeks of gestation using three different frame rate (FR) settings (≥ 110, 100±10, 60±10 frames per second). We assessed the segmental and the global LS of both ventricles (2C) and of the left ventricle (LV) offline with QLab 10.8 (Philips Medical Systems, Andover, MA, USA). Inter- and intraventricular SYN were calculated as time difference in peak myocardial strain between the mid-segments of left and right ventricle (interventricular, 2C_Syn) and lateral wall and septum of the left ventricle (intraventricular, LV_Syn), respectively. In 84.3% STE was feasible at all three FR settings. The LS increased in both views at higher FRs to a statistically noticeable extent. SYN measurements and the absolute differences at patient level between the FR settings showed no statistically noticeable alterations. STE is feasible at low and high FR settings. SYN emerges to be a robust parameter for fetal STE as it is less affected by the FR. High FRs enable high temporal resolutions and thus an accurate examination of fetal hearts. Future research for the technical implementation of tailored fetal STE software is necessary for reliable clinical application.

A Comparative Study of Systolic and Diastolic Mechanical Synchrony in Canine, Primate, and Healthy and Failing Human Hearts

Aim: Mechanical dyssynchrony (MD) is associated with heart failure (HF) and may be prognostically important in cardiac resynchronization therapy (CRT). Yet, little is known about its patterns in healthy or diseased hearts. We here investigate and compare systolic and diastolic MD in both right (RV) and left ventricles (LV) of canine, primate and healthy and failing human hearts.Methods and Results: RV and LV mechanical function were examined by pulse-wave Doppler in 15 beagle dogs, 59 rhesus monkeys, 100 healthy human subjects and 39 heart failure (HF) patients. This measured RV and LV pre-ejection periods (RVPEP and LVPEP) and diastolic opening times (Q-TVE and Q-MVE). The occurrence of right (RVMDs) and left ventricular systolic mechanical delay (LVMDs) was assessed by comparing RVPEP and LVPEP values. That of right (RVMDd) and left ventricular diastolic mechanical delay (LVMDd) was assessed from the corresponding diastolic opening times (Q-TVE and Q-MVE). These situations were quantified by values of interventricular systolic (IVMDs) and diastolic mechanical delays (IVMDd), represented as positive if the relevant RV mechanical events preceded those in the LV. Healthy hearts in all species examined showed greater LV than RV delay times and therefore positive IVMDs and IVMDd. In contrast a greater proportion of the HF patients showed both markedly increased IVMDs and negative IVMDd, with diastolic mechanical asynchrony negatively correlated with LVEF.Conclusion: The present IVMDs and IVMDd findings have potential clinical implications particularly for personalized setting of parameter values in CRT in individual patients to achieve effective treatment of HF.

Mechanical Synchrony and Myocardial Work in Heart Failure Patients With Left Bundle Branch Area Pacing and Comparison With Biventricular Pacing.

Background: Little is known about the efficacy of permanent left bundle branch area pacing (LBBAP) in delivering cardiac resynchronization therapy (CRT). This study aimed to evaluate the effect of LBBAP on mechanical synchronization and myocardial work (MW) in heart failure (HF) patients and to compare LBBAP with biventricular pacing (BVP).Methods: This is a multicenter, prospective cohort study. From February 2018 to January 2021, 62 consecutive HF patients with reduced ejection fraction (LVEF ≤ 35%) and complete left bundle branch block (CLBBB) who underwent LBBAP or BVP were enrolled in this study. Echocardiograms and electrocardiograms and were conducted before and 3–6 months after implantation. Intra- and interventricular synchronization were assessed using two-dimensional speckle tracking imaging (2D-STI). The left ventricular pressure-strain loop was obtained by combining left ventricular strain with non-invasive blood pressure to evaluate mechanical efficiency.Results: The echocardiographic response rates were 68.6 and 88.9% in the BVP and LBBAP groups, respectively. Left bundle branch area pacing resulted in significant QRS narrowing (from 177.1 ± 16.7 to 113.0 ± 18.4 ms, P < 0.001) and improvement in LVEF (from 29.9 ± 4.8 to 47.1 ± 8.3%, P < 0.001). The global wasted work (GWW) (410.3 ± 166.6 vs. 283.0 ± 129.6 mmHg%, P = 0.001) and global work efficiency (GWE) (64.6 ± 7.8 vs. 80.5 ± 5.7%, P < 0.001) were significantly improved along with shorter peak strain dispersion (PSD) (143.4 ± 45.2 vs. 92.6 ± 35.1 ms, P < 0.001) and interventricular mechanical delay (IVMD) (56.4 ± 28.5 vs. 28.9 ± 19.0 ms, P < 0.001), indicating its efficiency in improving mechanical synchronization. In comparison with BVP, LBBAP delivered greater improvement of QRS narrowing (−64.1 ± 18.9 vs. −32.5 ± 22.3 ms, P < 0.001) and better mechanical synchronization and efficiency.Conclusions: Left bundle branch area pacing was effective in improving cardiac function, mechanical synchronization, and mechanical efficiency and may be a promising alternative cardiac resynchronization therapy.

Cardiac synchronism assessment by myocardial perfusion imaging in patients with cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: None. Background the treatment of heart failure has undergone major therapeutic advances in recent decades, among them, cardiac resynchronization therapy (CRT), a strategy capable of reducing symptoms, hospitalization and mortality. It is known that up to 30% of patients undergoing CRT do not have a satisfactory response, based on current selection criteria. Purpose Myocardial perfusion scintigraphy by Gated-SPECT technique (Gated-SPECT) can provide important information such as mechanical timing, region of last mechanical activation and fibrosis which are very useful in the best selection of who would really benefit from this device. Objective to evaluate the presence of improvement in the mechanical synchronism of the left ventricle (LV) in patients with CRT, using the Synctool software used in the Gated-SPECT, as well as to correlate the data obtained with clinical improvement, defined by reduction of at least 1 New York Heart Association class and reduction of at least 5 points in the Minessota Living With Heart Failure Questionnaire (MLHFQ), and also correlate to other epidemiological, clinical, electrocardiographic and perfusional variables. Methods 31 patients (p) with CRT underwent Gated-SPECT at 2 different times: CRT on and off. A quality of life questionnaire was also applied and clinical data before and after implantation of the device were collected. Results improved synchronism with reduced histogram bandwidth (BWH) (215.6 ± 74.7 ° vs. 149.9 ± 67.9 °; p &amp;lt;0.001) and phase standard deviation (SD) (65, 3 ± 21.7 ° vs. 53.1 ± 22.7 °; p &amp;lt;0.001), after CRT is turned on. Patients who presented synchrony improvement had a higher frequency of clinical improvement (p = 0.026) and obtained lower values of LV end diastolic volume (204.4 ± 100.4 ml vs. 304.3 ± 77.2 ml; p = 0.028) and LV end-systolic volume (120.2 ± 88.8 ml vs. 197.5 ± 51.6 ml; p = 0.026). When clinical improvement was examined, 23 (74.1%) p were considered as responders and 8 (25.9%) as non-responders. Responders showed a significant increase in the LV ejection fraction (38.4 ± 14.1 vs. 47.9 ± 15.3; p &amp;lt;0.001). Non-responders had a higher mean of myocardial involvement by fibrosis (12.9 ± 5.5% vs. 5.7 ± 8.4%; p = 0.033) and higher frequency of fibrosis in the lateral and inferolateral walls (50% vs. 8.7%; p = 0.026), presented an even lower percentage of localization of the region of last mechanical activation (LMA) in the lateral and inferolateral walls (12.5% vs 56.5%; p = 0.045), thus assuming a discordant position between fibrosis and the CRT pacing electrode in the LV. Conclusion Synctoll software are very useful to predict the evaluation of patients with CRT wich was able to improve the mechanical timing of the LV. Improvement in mechanical synchrony is associated with clinical improvement and marked reverse remodeling. Presence of fibrosis and region of last mechanical activation in the lateral and inferolateral walls are predictive factors of response to CRT.

Safety and efficacy of left bundle branch pacing in comparison with conventional right ventricular pacing: A systematic review and meta-analysis.

Background:Right ventricular pacing (RVP) has been widely accepted as a traditional pacing strategy, but long-term RVP has detrimental impact on ventricular synchrony. However, left bundle branch pacing (LBBP) that evolved from His-bundle pacing could maintain ventricular synchrony and overcome its clinical deficiencies such as difficulty of lead implantation, His bundle damage, and high and unstable thresholds. This analysis aimed to appraise the clinical safety and efficacy of LBBP.Methods:The Medline, PubMed, Embase, and the Cochrane Library databases from inception to November 2020 were searched for studies comparing LBBP and RVP.Results:Seven trials with 451 patients (221 patients underwent LBBP and 230 patients underwent RVP) were included in the analysis. Pooled analyses verified that the paced QRS duration (QRSd) and left ventricular mechanical synchronization parameters of the LBBP capture were similar with the native-conduction mode (P > .7),but LBBP showed shorter QRS duration (weighted mean difference [WMD]: −33.32; 95% confidence interval [CI], −40.44 to −26.19, P < .001), better left ventricular mechanical synchrony (standard mean differences: −1.5; 95% CI: −1.85 to −1.14, P < .001) compared with RVP. No significant differences in Pacing threshold (WMD: 0.01; 95% CI: −0.08 to 0.09, P < .001), R wave amplitude (WMD: 0.04; 95% CI: −1.12 to 1.19, P = .95) were noted between LBBP and RVP. Ventricular impedance of LBBP was higher than that of RVP originally (WMD: 19.34; 95% CI: 3.13–35.56, P = .02), and there was no difference between the 2 groups after follow-up (WMD: 11.78; 95% CI: −24.48 to 48.04, P = .52). And follow-up pacing threshold of LBBP kept stability (WMD: 0.08; 95% CI: −0.09 to 0.25, P = .36). However, no statistical difference existed in ejection fraction between the 2 groups (WMD: 1.41; 95% CI: −1.72 to 4.54, P = .38).Conclusions:The safety and efficacy of LBBP was firstly verified by meta-analysis to date. LBBP markedly preserve ventricular electrical and mechanical synchrony compared with RVP. Meanwhile, LBBP had stable and excellent pacing parameters. However, LBBP could not be significant difference in ejection fraction between RVP during short- term follow-up.

A pilot study to determine if left ventricular activation time is a useful parameter for left bundle branch capture: Validated by ventricular mechanical synchrony with SPECT imaging

BackgroundLeft bundle branch (LBB) pacing has emerged as a novel pacing modality. Left ventricular activation time (LVAT) was reported to be associated with the activation via LBB, but the value of LVAT for determining LBB pacing was unknown. We conducted a pilot study to determine if LVAT could define LBB capture by validating left ventricular (LV) mechanical synchrony. MethodsWe analyzed LVAT in 68 bradycardia-indicated patients who received LBB pacing. LVAT was measured from the stimulus to R-wave peak in lead V5 and V6. LV mechanical synchrony assessed by SPECT MPI was compared according to the value of LVAT and the presence of LBB potential. ResultsThe mean LVAT was 75.4 ± 12.7 ms. LBB potential was recorded in 47 patients (69.1%). Patients with LVAT < 76 ms had better LV mechanical synchrony than those with LVAT ≥ 76 ms. Patients with LVAT < 76 ms or LBB potential had better mechanical synchrony than those with LVAT ≥ 76 ms and no potential. LVAT < 76 ms could predict the normal synchrony with a sensitivity of 88.9% and a specificity of 87.5%. ConclusionA short LVAT indicated favorable mechanical synchrony in SPECT imaging. LVAT < 76 ms might be a practical parameter for defining LBB capture.

Left Ventricular Function Assessment of Patients with Postoperative Ventricular Septal Defect Closure by Longitudinal Strain on Two-Dimensional Echocardiography 1 Year after Surgery

Background: Patients with large perimembranous ventricular septal defects (pm-VSDs) undergo surgical repair with prosthetic material during infancy. However, the effect of the presence of akinetic patch in the ventricular septum on the left ventricular (LV) mechanical synchrony and ventricular function has not been studied. In our study, we assessed LV function in postoperative pm-VSD closure patients on two-dimensional (2D) echocardiography (echo) after 1 year of surgery using biplane Simspon's method, fractional shortening (FS), and global longitudinal strain (GLS) to assess the regional strain pattern. Methods: This was a a single-institution observational study. Patients following up 1 year after surgical ventricular septal defect closure at our institute were enrolled. On follow-up, detailed 2D echo was done with special emphasis on left atrial size, LV size (by M-mode), and presence of any residual shunt. LV function was assessed using biplane Simpson's method and longitudinal strain on 2D echo. GLS was measured in three standard apical views. Results: Of the 121 patients enrolled, 101 patients fulfilling the inclusion and exclusion criteria were analyzed. Of these 101 patients, 75.2% were males. The median age at follow-up after surgery was 3.67 ± 2.7 years. About 92.1% of patients did not have residual VSD lesion. No patient had pulmonary arterial hypertension. All except one patient had normal ventricular function. Patients with ventricular dysfunction had LV ejection fraction (LVEF) of 47%, GLS –17.4%, and FS −20.5%. The mean values of FS, LVEF, and GLS were 32.0 ± 5.28%, 62.2% ± 4.2%, and −26.53 ± 2.93%, respectively, in pm-VSD closure patients. Regional strain pattern analysis showed significantly lower strain values in basal anteroseptal segment with a mean of −21.4 ± 2.7%. FS and GLS were noted to have significant correlation with each other (P = 0.01) and LVEF by biplane Simpson's method and GLS had significant correlation with each other (P = 0.0001). Conclusions: GLS has strong correlation with LVEF by Simson's method and FS. Basal anteroseptal segment in pm-VSD patients had significantly lower strain values compared to other segments. There is no significant correlation between age at surgery and GLS in pm-VSD closure patients who were operated within 1 year of age. The type of VSD closure does not have significant influence on GLS.

Assessment of right atrial dyssynchrony by 2D speckle-tracking in healthy young men following high altitude exposure at 4100 m.

BackgroundHigh altitude exposure induces overload of right-sided heart and may further predispose to supraventricular arrhythmia. It has been reported that atrial mechanical dyssynchrony is associated with atrial arrhythmia. Whether high altitude exposure causes higher right atrial (RA) dyssynchrony is still unknown. The aim of study was to investigate the effect of high altitude exposure on right atrial mechanical synchrony.MethodsIn this study, 98 healthy young men underwent clinical examination and echocardiography at sea level (400 m) and high altitude (4100 m) after an ascent within 7 days. RA dyssynchrony was defined as inhomogeneous timing to peak strain and strain rate using 2D speckle-tracking echocardiography.ResultsFollowing high altitude exposure, standard deviation of the time to peak strain (SD-TPS) [36.2 (24.5, 48.6) ms vs. 21.7 (12.9, 32.1) ms, p<0.001] and SD-TPS as percentage of R–R’ interval (4.6 ± 2.1% vs. 2.5 ± 1.8%, p<0.001) significantly increased. Additionally, subjects with higher SD-TPS (%) at high altitude presented decreased right ventricular global longitudinal strain and RA active emptying fraction, but increased RA minimal volume index, which were not observed in lower group. Multivariable analysis showed that mean pulmonary arterial pressure and tricuspid E/A were independently associated with SD-TPS (%) at high altitude.ConclusionOur data for the first time demonstrated that high altitude exposure causes RA dyssynchrony in healthy young men, which may be secondary to increased pulmonary arterial pressure. In addition, subjects with higher RA dyssynchrony presented worse RA contractile function and right ventricular performance.

Efficacy of upgrading to left bundle branch pacing in patients with heart failure after right ventricular pacing.

Chronic right ventricular (RV) pacing is associated with an increased incidence of heart failure and mortality. Left bundle branch (LBB) pacing could produce near-physiological electrical activation and mechanical synchrony. We aimed to report the effects of upgrading to LBB pacing in heart failure patients after chronic RV pacing. The indications included pacing-induced cardiomyopathy (PICM) in Group 1 and heart failure after RV pacing with left ventricular ejection fraction (LVEF) ≥ 50% in Group 2. LBB pacing was achieved by penetrating the pacing lead to the subendocardium of left-sided interventricular septum through the venous access. Left ventricular activation time (LVAT) was measured from the pacing stimulus to the ascending peak of lead V5 or V6. All patients underwent clinical and echocardiographic evaluations before and after upgrading. Totally 27 patients (13 in Group 1 and 14 in Group 2) were consecutively enrolled. The mean follow-up time after upgrade was 10.4 ± 6.1 months. Paced QRS duration was significantly shortened from 174.1 ± 15.8milliseconds to 116.6 ± 11.7milliseconds (p<.0001). The mean LVAT was 83.2 ± 11.7milliseconds. LVEF increased from 40.3 ± 5.2% before upgrading to 48.1 ± 9.5% at follow-up in patients with PICM. Serum N-terminal probrain natriuretic peptide levels decreased and New York Heart Association classification improved in both groups. No upgrade-related complications were observed. Upgrading to LBB pacing was feasible and effective with improved cardiac function in heart failure patients with both reduced and preserved LVEF after RV pacing.

Nonselective versus selective His bundle pacing: An acute intrapatient speckle‐tracking strain echocardiographic study

We aimed to compare the acute differences in left ventricular (LV) function and mechanical synchrony during nonselective His bundle pacing (ns-HBP) versus selective His bundle pacing (s-HBP) using strain echocardiography. Consecutive patients with permanent His bundle pacing, in whom it was possible to obtain both s-HBP and ns-HBP, were studied in two centers. In each patient, echocardiography was performed sequentially during s-HBP and ns-HBP. Speckle-tracking echocardiography parameters were analyzed: Global longitudinal strain (GLS), the time delay between peak systolic strain in the basal septaland basal lateral segments (BS-BL delay), peak strain dispersion (PSD) and strain delay index. Right ventricle function was assessed using tricuspid annular plane systolic excursion (TAPSE) and tissue Doppler velocity of the lateral tricuspid annulus (S'). A total of 69 patients (age: 75.6 ± 10.5 years; males: 75%) were enrolled. There were no differences in LV ejection fraction and GLS between s-HBP and ns-HBP modes: 59% versus 60%, and -15.6% versus -15.7%, respectively; as well as no difference in BS-BL delay and strain delay index. The PSD value was higher in the ns-HBP group than in the s-HBP group with the most pronounced difference in the basal LV segments. No differences in right ventricular function parameters (TAPSE and S') were found. The ns-HBP and s-HBP modes seem comparable regarding ventricular function. The dyssynchrony parameters were significantly higher during ns-HBP, however, the difference seems modest and clarification of its impact on LV function requires a larger long-term study.

Velocity Vector Imaging to Assess Longitudinal Wall Motion of Adult Carotid Arteries.

We aimed to assess longitudinal wall motion of the common carotid artery (CCA) using velocity vector imaging (VVI). From October 2018 to July 2019, we prospectively performed VVI of 204 CCAs (102 adult volunteers, 57 men, 45 women) in young (n = 40, 20-44 y), mid-age (n = 30, 45-64 y), and senior (n = 32, ≥65 y) groups. VVI parameters of CCA included longitudinal motion pattern, motion parameters (strain, strain rate, displacement), and time-to-peak motion parameters (time-to-peak strain, time-to-peak strain rate, time-to-peak displacement). Statistical analyses included one-way ANOVA post-hoc testing to examine the difference in VVI parameters among the 3 age groups and in paired groups; unpaired t tests to examine the difference in VVI parameters between CCAs with and without atherosclerotic plaque, between hypertensive and normotensive subjects without atherosclerotic plaque; linear regression to analyze correlations of VVI parameters to age, carotid intima-media thickness; and intraclass correlation coefficient to test inter- and intra-observer reliability in performing VVI of the CCA. Differences in VVI parameters and patterns among the 3 age groups, between hypertensive and normotensive, and CCAs with and without plaque were significant (p < .01). CCA motion- and time-to-peak motion parameters were correlated to age (R2 = 0.63-0.56) and carotid intima-media thickness (R2 = 0.29-0.22). CCA wall motion dyssynchrony was remarkable in seniors. The repeatability and reproducibility for performing carotid artery VVI were good (intraclass correlation coefficient > 0.85). VVI is feasible to assess changes in longitudinal CCA wall mechanical properties and synchrony with aging, atherosclerosis, and hypertension.