Electromechanical Dyssynchrony Research Articles

Right ventricular pacing-evoked left ventricular dysfunction is exaggerated by sustained left ventricular pressure overload in a rat model

Abstract Introduction A growing body of evidence suggests that in the presence of left bundle branch block-induced electromechanical dyssynchrony, the function of the left ventricle (LV) becomes extremely sensitive to arterial afterload. However, data is scarce whether right ventricular pacing (RVP) also sensitizes the LV to alterations in afterload. Purpose Hence, in the present translational study we aimed to characterize the acute effect of RVP on LV hemodynamics under standard laboratory conditions using a rat model of chronic LV pressure overload (PO). Methods Transverse aortic constriction (TAC group) was carried out in male Wistar rats to evoke sustained LV PO for six weeks. Age- and sex-matched sham-operated animals served as controls (Sham group). LV hemodynamics was assessed in anesthetized rats by pressure-volume analysis using a pressure-conductance micro-catheter (SPR-838) introduced to the LV via the right carotid artery. To evoke RVP, the right jugular vein was cannulated and an ultra-miniature octopolar electrophysiology catheter (EPR-800) was placed into the right ventricle. Pressure-volume loops were registered in the TAC and the Sham groups during intrinsic narrow QRS rhythm (termed as TAC-Vsense and Sham-Vsense) as well as during RVP (termed as TAC-Vpace and Sham-Vpace). Results RVP was associated with impaired diastolic function (active relaxation time constant [τ]: 8.6±0.3 vs. 9.6±0.3ms, Sham-Vsense vs. Sham-Vpace and 8.0±0.3 vs. 9.6±0.4ms, TAC-Vsense vs. TAC-Vpace; P<0.001 for both comparisons) and decreased LV contractility (preload recruitable stroke work [PRSW]: 139±9 vs. 114±9mmHg, Sham-Vsense vs. Sham-Vpace and 255±23 vs. 169±17mmHg, TAC-Vsense vs. TAC-Vpace; P<0.001 for both comparisons) in both the TAC and the Sham groups. Nevertheless, the extent of RVP-evoked active relaxation prolongation (Δτ: 12±2 vs. 20±2%, Sham vs. TAC, P=0.005) and LV contractility reduction (ΔPRSW: -18±4 vs. -34±3%, Sham vs. TAC, P=0.007) was found to be more robust in rats with sustained LV PO compared to controls. Conclusion Our experimental results indicate that RVP-induced LV dysfunction is exaggerated in case of sustained LV PO.

Comparison between left bundle branch area pacing and right ventricular pacing: ventricular electromechanical synchrony and risk of atrial high-rate episodes.

The electromechanical dyssynchrony associated with right ventricular pacing (RVP) has been found to have adverse impact on clinical outcomes. Several studies have shown that left bundle branch area pacing (LBBAP) has superior pacing parameters compared with RVP. We aimed to assess the difference in ventricular electromechanical synchrony and investigate the risk of atrial high-rate episodes (AHREs) in patients with LBBAP and RVP. We consecutively identified 40 patients with atrioventricular block and no prior atrial fibrillation. They were divided according to the ventricular pacing sites: the LBBAP group and the RVP group (including the right ventricular apical pacing (RVA) group and the right side ventricular septal pacing (RVS) group). Evaluation of ventricular electromechanical synchrony was implemented using electrocardiogram and two-dimensional speckle tracking echocardiography (2D-STE). AHRE was defined as event with an atrial frequency of ≥176 bpm lasting for ≥6 min recorded by pacemakers during follow-up. The paced QRS duration of the LBBAP group was significantly shorter than that of the other two groups: LBBAP 113.56 ± 9.66 ms vs. RVA 164.73 ± 14.49 ms, p < 0.001; LBBAP 113.56 ± 9.66 ms vs. RVS 148.23 ± 17.3 ms, p < 0.001. The LBBAP group showed shorter maximum difference (TDmax), and standard deviation (SD) of the time to peak systolic strain among the 18 left ventricular segments, and time of septal-to-posterior wall motion delay (SPWMD) compared with the RVA group (TDmax, 87.56 ± 56.01 ms vs. 189.85 ± 91.88 ms, p = 0.001; SD, 25.40 ± 14.61 ms vs. 67.13 ± 27.40 ms, p < 0.001; SPWMD, 28.75 ± 21.89 ms vs. 99.09 ± 46.56 ms, p < 0.001) and the RVS group (TDmax, 87.56 ± 56.01 ms vs. 156.46 ± 55.54 ms, p = 0.003; SD, 25.40 ± 14.61 ms vs. 49.02 ± 17.85 ms, p = 0.001; SPWMD, 28.75 ± 21.89 ms vs. 91.54 ± 26.67 ms, p < 0.001). The interventricular mechanical delay (IVMD) was shorter in the LBBAP group compared with the RVA group (-5.38 ± 9.31 ms vs. 44.82 ± 16.42 ms, p < 0.001) and the RVS group (-5.38 ± 9.31 ms vs. 25.31 ± 21.36 ms, p < 0.001). Comparing the RVA group and the RVS group, the paced QRS duration and IVMD were significantly shorter in the RVS group (QRS duration, 164.73 ± 14.49 ms vs. 148.23 ± 17.3 ms, p = 0.02; IVMD, 44.82 ± 16.42 ms vs. 25.31 ± 21.36 ms, p = 0.022). During follow-up, 2/16 (12.5%) LBBAP patients, 4/11 (36.4%) RVA patients, and 8/13 (61.5%) RVS patients had recorded novel AHREs. LBBAP was proven to be independently associated with decreased risk of AHREs than RVP (log-rank p = 0.043). LBBAP generates narrower paced QRS and better intro-left ventricular and biventricular contraction synchronization compared with traditional RVP. LBBAP was associated with a decreased risk of AHREs compared with RVP.

How to assess and treat right ventricular electromechanical dyssynchrony in post-repair tetralogy of Fallot: insights from imaging, invasive studies, and computational modelling.

Right bundle branch block (RBBB) and resulting right ventricular (RV) electromechanical discoordination are thought to play a role in the disease process of subpulmonary RV dysfunction that frequently occur post-repair tetralogy of Fallot (ToF). We sought to describe this disease entity, the role of pulmonary re-valvulation, and the potential added value of RV cardiac resynchronization therapy (RV-CRT). Two patients with repaired ToF, complete RBBB, pulmonary regurgitation, and significantly decreased RV function underwent echocardiography, cardiac magnetic resonance, and an invasive study to evaluate the potential for RV-CRT as part of the management strategy. The data were used to personalize the CircAdapt model of the human heart and circulation. Resulting Digital Twins were analysed to quantify the relative effects of RV pressure and volume overload and to predict the effect of RV-CRT. Echocardiography showed components of a classic RV dyssynchrony pattern which could be reversed by RV-CRT during invasive study and resulted in acute improvement in RV systolic function. The Digital Twins confirmed a contribution of electromechanical RV dyssynchrony to RV dysfunction and suggested improvement of RV contraction efficiency after RV-CRT. The one patient who underwent successful permanent RV-CRT as part of the pulmonary re-valvulation procedure carried improvements that were in line with the predictions based on his Digital Twin. An integrative diagnostic approach to RV dysfunction, including the construction of Digital Twins may help to identify candidates for RV-CRT as part of the lifetime management of ToF and similar congenital heart lesions.

Physiological pacing: just a lot of buzz or the next paradigm shift in bradycardia pacing?

Cardiac pacing has been an established therapy for bradyarrhythmia due to sinus or atrioventricular nodal disease since the 1950s. However, contemporary studies have shown that conventional right ventricular pacing (RVP) causes electromechanical dyssynchrony, which can lead to atrial fibrillation, heart failure and even death. Recently, the push for a more physiological cardiac pacing has seen a revival in the utilisation and development of conduction system pacing (CSP). There has been a shift towards adopting His bundle pacing (HBP) or left bundle branch area pacing (LBBaP) in bradycardia patients worldwide and in Singapore. This review serves to outline the electrophysiological concepts behind CSP and illustrate the different paced electrocardiogram characteristics of HBP, LBBaP and RVP to aid understanding of this revolutionary pacing approach among medical practitioners in Singapore.

A porcine large animal model of radiofrequency ablation-induced left bundle branch block.

Electrocardiographic (ECG) features of left bundle branch (LBB) block (LBBB) can be observed in up to 20%-30% of patients suffering from heart failure with reduced ejection fraction. However, predicting which LBBB patients will benefit from cardiac resynchronization therapy (CRT) or conduction system pacing remains challenging. This study aimed to establish a translational model of LBBB to enhance our understanding of its pathophysiology and improve therapeutic approaches. Fourteen male pigs underwent radiofrequency catheter ablation of the proximal LBB under fluoroscopy and ECG guidance. Comprehensive clinical assessments (12-lead ECG, bloodsampling, echocardiography, electroanatomical mapping) were conducted before LBBB induction, after 7, and 21days. Three pigs received CRT pacemakers 7days after LBB ablation to assess resynchronization feasibility. Following proximal LBB ablation, ECGs displayed characteristic LBBB features, including QRS widening, slurring in left lateral leads, and QRS axis changes. QRS duration increased from 64.2 ± 4.2ms to 86.6 ± 12.1ms, and R wave peak time in V6 extended from 21.3 ± 3.6ms to 45.7 ± 12.6ms. Echocardiography confirmed cardiac electromechanical dyssynchrony, with septal flash appearance, prolonged septal-to-posterior-wall motion delay, and extended ventricular electromechanical delays. Electroanatomical mapping revealed a left ventricular breakthrough site shift and significantly prolonged left ventricular activation times. RF-induced LBBB persisted for 3weeks. CRT reduced QRS duration to 75.9 ± 8.6ms, demonstrating successful resynchronization. This porcine model accurately replicates the electrical and electromechanical characteristics of LBBB observed in patients. It provides a practical, cost-effective, and reproducible platform to investigate molecular and translational aspects of cardiac electromechanical dyssynchrony in a controlled and clinically relevant setting.

Conduction System Pacing for Patients with Congenital Heart Disease.

For patients with congenital heart disease (CHD), chronic ventricular pacing may lead to progressive cardiomyopathy owing to electromechanical dyssynchrony. Cardiac conduction system pacing (CSP) has been proposed as a physiologic pacing strategy-directly engaging the His-Purkinje system and preserving electromechanical synchrony. CSP may be indicated for a wide variety of children and adults with CHD and has emerged as an important tool in the armamentarium for cardiac implantable electronic device operators. This review provides the rationale, background, and supportive evidence for CSP in patients with CHD and discusses implant strategies and outcomes in the context of dominant ventricular morphologic categories.

Left bundle branch block cardiomyopathy: an intriguing and defiant entity from diagnosis to treatment

Abstract Introduction and objectives Left bundle branch block cardiomyopathy (LBBB-CM) is an increasingly recognized entity, where electromechanical dyssynchrony seems to play a central role in left ventricular dysfunction (LVD) development. This is a challenging and scarcely studied topic, as causality dilemma between LBBB and LVD is still unsolved. Our aim is to increase current evidence on the subject by analyzing a population of idiopathic LBBB patients (pts) who developed, at some point, LVD not explained by other causes. Methods Retrospective study of LBBB adult pts screened from a large tertiary care hospital electrocardiographic database from 2011 to 2017. After careful evaluation, only possible LBBB-CM pts with serial follow-up (FU) echocardiographic and clinical data were included in the analysis. Results 53 pts were identified as possible LBBB-CMP. At baseline, 44% presented left ventricular ejection fraction (LVEF)&amp;gt;50%, while 56% had LVD. 51% were female and mean age at first-ever LBBB report was 59 years-old. All cohort presented echocardiographic mechanical desynchrony, and additional testing to exclude other causes of LVD (non-invasive ischemia testing in 78%; coronariography in 68%; cardiac magnetic resonance in 38%). Median FU time was 10 years. Worst-LVD was reported as severe in 49% of pts, moderate in 23% and mild in 28%. Median time-to-dysfunction in those with initial LVEF&amp;gt;50% was 8 years. 77% of pts presented heart-failure (HF) symptoms. 40% and 42% presented at least 1 CV event and CV hospitalization, respectively. Most events and/or hospitalizations were due to acute decompensated HF. 2 CV deaths were observed. Cardiac resynchronization therapy (CRT) devices were implanted in 47% of pts. All presented clinical improvement after implantation, and LVEF significantly increased (pre-CRT median LVEF of 24% vs 48% post-CRT; p&amp;lt;0.001). When comparing pts with vs without CRT (Figure 1), better LVEF improvements were achieved in CRT group (median LVEF improvement of 27% in CRT vs 11%; p&amp;lt;0.001). Repeating the latter analysis in pts who only presented at least moderate dysfunction, higher LVEF increase was also reported in CRT group (median LVEF improvement of 27% in CRT pts vs 14%; p=0.002), and significantly more CRT pts recovered LV function (50% CRT vs 14% non-CRT; p=0.028). Notably, no differences were found in rates of medical HF therapy between groups (p=1). Conclusion Our data shows LBBB-CM as a diagnosis of exclusion, where careful evaluation of other LVD etiologies should be performed and discarded. We highlight important morbidity rates in this population, namely HF hospitalizations, as well as the apparently critical role of CRT implantation in these pts. All our CRT pts responded excellently to the therapy. Thus, our study raises awareness to the emerging question of whether this entity can be reversed after LBBB correction with CRT and if early intervention would be desirable.Figure 1

Left ventricular afterload reduction by transcatheter aortic valve implantation acutely alleviates right ventricular pacing-induced left ventricular dysfunction in patients with aortic stenosis

Abstract Introduction In patients with left bundle branch block (LBBB) cardiac function has been found to be particularly sensitive to alterations in left ventricular (LV) afterload. Nevertheless, whether the detrimental hemodynamic effect of right ventricular pacing (RVP)-induced electromechanical dyssynchrony on LV function is also associated with afterload dependency, has not been investigated yet. Purpose Hence, in the current study we sought to examine the acute effect of RVP on LV function in patients with aortic stenosis (AS) before (with elevated afterload) and after (without elevated afterload) transcatheter aortic valve implantation (TAVI). Methods Patients with a previously implanted permanent pacemaker (PM) and significant AS referred for TAVI at our heart and vascular center university were screened for this observational study. Only those patients who had an intrinsic, regular, narrow QRS or right bundle branch block (RBBB) morphology rhythm were included. From 2022 March to 2023 February, nine patients with a DDD PM (with sick sinus syndrome and maintained AV conduction) and four patients with a VVI PM (with atrial fibrillation and complete AV block but stable junctional escape rhythm) were enrolled. Following TAVI, four patients were excluded due to the development of new-onset persistent LBBB. Transthoracic conventional and advanced echocardiography and non-invasive blood pressure monitoring were performed immediately before TAVI and on the second postoperative day. The measurements were carried out during intrinsic QRS rhythm and during frequency-matched RVP as well. Global longitudinal strain was determined by speckle-tracking echocardiography, then using LV pressure curves estimated from systolic blood pressure and mean aortic gradient, global myocardial work index (GMWI) was calculated to assess LV contractility. Results Mean aortic gradient was decreased after TAVI (40.2±3.6 vs. 6.7±1.3mmHg before vs. after TAVI, P&amp;lt;0.001) indicating successful reduction of LV afterload. Compared to the intrinsic QRS rhythm, RVP decreased GMWI before TAVI (GMWI: 1967±206 vs. 1240±174mmHg% intrinsic QRS vs. RVP, P&amp;lt;0.001) and after TAVI (GMWI: 1399±149 vs. 1020±121mmHg% intrinsic QRS vs. RVP, P=0.019) as well. Nevertheless, the extent of RVP-induced LV contractility impairment (expressed as ΔGMWI) was significantly alleviated after pressure unloading therapy (ΔGMWI: -37.1±6.6 vs. -24.5±7.8% before TAVI vs. after TAVI, P=0.024). Conclusion Our preliminary results indicate that RVP-induced LV dysfunction is afterload dependent. Hence, in patients with AS and a high percentage of RVP, TAVI might entail substantial functional improvement.

Association of leadless pacing with ventricular and valvular function.

Traditional transvenous pacemakers are associated with worsening tricuspid valve function due to lead-related leaflet impingement, as well as ventricular dysfunction related to electromechanical dyssynchrony from chronic right ventricular (RV) pacing. The association of leadless pacing with ventricular and valvular function has not been well established. We aimed to assess the association of leadless pacemaker placement with changes in valvular regurgitation and ventricular function. Echocardiographic features before and after leadless pacemaker implant were analyzed in consecutive patients who received a leadless pacemaker with pre- and postprocedure echocardiography at Duke University Hospital between November 2014 and November 2019. Valvular regurgitation was graded ordinally from 0 (none) to 3 (severe). Among 54 patients, the mean age was mean age was 70.1 ± 14.3 years, 24 (44%) were women, and the most frequent primary pacing indication was complete heart block in 24 (44%). The median RV pacing burden was 45.4 (interquartile range [IQR] 3.5-97.0). On echocardiogram performed 8.9 months (IQR 4.5-14.5) after implant, there was no change in the average severity of tricuspid regurgitation (mean change 0.07 ± 1.15, p = .64) from pre-procedure echocardiogram. We observed a decrease in the average left ventricular ejection fraction (LVEF) (52.3 ± 9.3 to 47.9 ± 12.1, p = .0019) and tricuspid annular plane systolic excursion (TAPSE) (1.8 ± 0.6 to 1.6 ± 0.4, p = .0437). Thirteen patients (24%) had absolute drop in LVEF of ≥10%. We did not observe short term worsening valvular function in patients with leadless pacemakers. However, consistent with the pathophysiologic impact of RV pacing, leadless pacing was associated with a reduction in biventricular function.

The Utility of Low-Dose-Dobutamine Stress Echocardiography in Patients with Heart Failure with Reduced Ejection Fraction: An Update.

Despite significant advancements in medical therapy, heart failure with reduced ejection fraction (HFrEF) continues to be a significant cause of death and disability. Reversible ischaemic left ventricular dysfunction due to viable myocardium is one such contributing factor. In these cases, coronary revascularization has shown promise in improving left ventricular function and prognosis. For patients with HFrEF and wide QRS, cardiac resynchronization therapy (CRT) is an effective option to address electromechanical dyssynchrony. However, approximately 30% of patients do not respond positively to CRT, highlighting the need to refine candidate selection for this treatment. In some patients with reduced HFrEF, there is a condition known as classical low-flow, low-gradient aortic stenosis (AS) that may be observed. This condition is characterized by a low transaortic flow, which leads to reductions in both the transaortic mean gradient and aortic valve area. Decision-making regarding revascularization, CRT, and pharmacological treatment play a crucial role in managing HFrEF. Cardiac imaging can be valuable in guiding decision-making processes and assessing the prognosis of patients with HFrEF. Among the imaging modalities, dobutamine stress echocardiography has come a long way in establishing itself as a feasible, safe, effective, relatively cheap non-invasive technique. The aim of this review is to explore the current literature on the utility of low-dose stress echocardiography in diagnosing and prognosticating patients with HFrEF.

Left ventricular endocardial activation maps during right ventricular pacing in pediatric patients.

Cardiac pacing from right ventricular (RV) sites may cause electromechanical ventricular dyssynchrony. Invasive and noninvasive mapping studies showed left ventricular (LV) activation sequence in adults. Aim of this study was to seek out the LV endocardial activation (LVEA) in pediatric patients who underwent RV pacing. Single-center, prospective study conducted on pediatric patients who underwent left sided catheter ablation of accessory pathways with the Carto Univu mapping system. After successful ablation procedures, LVEA was recorded by the ablation catheter during sinus rhythm (SR) and during para-hisian (PHP), midseptum (MSP), and apical (RVAP) pacing. Seventeen patients, 13 males, aged 12 (10-15) years, registered LV activation maps and times (LVAT). SR showed significantly shorter LVAT than during pacing. LVAT of PHP was shorter than MSP, while there were not significant differences among PHP and MSP versus RVAP. In SR initial LV endocardial activation occurred in two midseptum sites, inferior-posterior and superior-anterior. During PHP, initial activation occurred at parahisian basal septum, rapidly followed by midseptum as in SR. During MSP and RVAP initial activation occurred at midseptum and apex, respectively. From all initial sites, the excitation spreads toward the base of the lateral LV free wall. A mild linear correlation was found between QRS duration and LVAT for MSP and for PHP. In pediatric patients LVEA maps during RV pacing showed that the shortest LVAT was obtained with PHP. The LV activation pattern seemed similar in sinus rhythm, PHP and MSP, from midseptum to LV lateral base.

Electromechanical Dyssynchrony Is Associated With Right Ventricular Remodeling and Dysfunction Independently of Pulmonary Regurgitation Late After Tetralogy of Fallot Repair

The aim of this study was to investigate the relationship among right ventricular (RV) dilatation, dysfunction, and electromechanical dyssynchrony (EMD) in patients with repaired tetralogy of Fallot (rTOF). Data from a prospective rTOF registry of subjects with moderate or greater pulmonary regurgitation (PR) and contemporary imaging were analyzed. Electrocardiograms and echocardiograms were analyzed for EMD (prolonged QRS duration [QRSd], echocardiographic septal flash, and mechanical delay) and mechanical dispersion. The relationship among these, RV measurements on cardiac magnetic resonance, exercise capacity, and incident arrhythmia or death was analyzed with adjustment for PR. In total, 271 patients with rTOF (42% women; median age, 32years; interquartile range [IQR], 23-34 years) were included. Patients had moderate to severe PR (median PR fraction, 38%; IQR, 30%-47%), moderate to severe RV enlargement (median RV end-diastolic volume index, 161 mL/m2; IQR, 138-186 mL/m2) and mild RV systolic dysfunction (median RV ejection fraction [RVEF], 44%; IQR, 38%-48%). Eleven patients (4%) experienced ventricular arrhythmia or death. Presence of EMD was associated with larger RV size (RV end-diastolic volume index and RV end-systolic volume index, P=.006 and P<.001, respectively) and lower RVEF (P<.001). A sharp inflection in the relation among QRSd, RV size, and RVEF was observed when QRSd exceeded 150msec (3.1% decrease in RVEF for every 20-msec increase in QRSd between 160 and 200msec). Similar inflection points were observed for the mechanical delay between the RV basal-lateral and midseptal segments. The mechanical delay was higher in patients with vs without incident atrial arrhythmia (371 vs 276msec, P=.014). In adults with rTOF, EMD is independently associated with larger RV size, lower RVEF, and incident atrial arrhythmias.

PO-05-026 IMPACT OF LEADLESS PACING ON VENTRICULAR AND VALVULAR FUNCTION

Traditional transvenous pacemakers have been associated with worsening tricuspid valve (TV) function due to lead-related leaflet impingement, as well as ventricular dysfunction related to electromechanical dyssynchrony from right ventricular pacing. The effect of leadless pacing on ventricular and valvular function has not been well established. To describe the impact of leadless pacing on ventricular and valvular function In patients who underwent a leadless pacemaker implant at Duke University Hospital between November 11, 2014 and November 18, 2019 and had pre- and post-procedure echocardiographic imaging, echocardiographic features before and after implant were assessed. Valvular regurgitation was graded ordinally from 0 (none) to 3 (severe). Left ventricular function was quantified by left ventricular ejection fraction (LVEF) and right ventricular function by tricuspid annular plane systolic excursion (TAPSE). Among 54 consecutive patients, the mean age was 70.1 ± 14.3 years, 44% were women, and the most frequent pacing indication was complete heart block (44%). The mean right ventricular pacing burden was 48.6 ± 42.6%. Over a mean echocardiographic follow-up time of 28.7 ± 19.8 months, there was no change in regurgitation severity of the mitral valve (mean change -0.17 ± 1.02, p= 0.24), tricuspid valve (mean change 0.07 ± 1.15, p=0.64), or aortic valve (mean change 0.11 ± 0.77, p=0.29) (Figure). There was no significant change in mean bi-atrial or bi-ventricular chamber size. There was a post-implant decrease in mean LVEF (52.3 ± 9.3 to 47.9 ± 12.1, p=0.0019) and TAPSE (1.8 ± 0.6 to 1.6 ± 0.4, p=0.0437) (Table). Neither change in LVEF nor TAPSE correlated with implant location (apical [n=46] vs non-apical septum [n=7]). Overall, 8 patients (15%) were diagnosed with pacing-related cardiomyopathy and 6 (11%) received an upgrade to a transvenous biventricular pacemaker. Patients with leadless pacemakers experienced no significant change in tricuspid regurgitation post-implant. However, right ventricular leadless pacing was associated with reduction in measures of both right and left ventricular function. These findings may impact selection of a leadless versus transvenous pacing system in patients with pre-existing TR or who are vulnerable to decline in ventricular function.

Dyssynchrony and Response to Cardiac Resynchronization Therapy in Heart Failure Patients With Unfavorable Electrical Characteristics

BackgroundAmong heart failure (HF) patients undergoing cardiac resynchronization therapy (CRT), those with unfavorable electrical characteristics (UEC) are less frequently CRT responders. ObjectivesIn this study, the authors sought to evaluate the relationship between preprocedural echocardiographic parameters of electromechanical dyssynchrony (EMD) and outcome following CRT. MethodsAmong 551 patients receiving CRT, 121 with UEC, defined as atypical left bundle branch, presence of right bundle branch block, or unspecified intraventricular conduction disturbance, were enrolled. Indices of EMD were presence of septal flash, apical rocking, septal deformation patterns, and global wasted work (GWW), determined with the use of speckle-tracking strain echocardiography. Endpoints were response to CRT, defined as a relative decrease in left ventricular end-systolic volume ≥15% at 9-month postoperative follow-up, and all-cause death or HF hospitalization during follow-up. ResultsAmong the 121 patients, 68 (56%) were CRT responders. In multivariate analysis, GWW ≥200 mm Hg% (adjusted odds ratio [aOR]: 4.17 [95% CI: 1.33-14.56]; P = 0.0182) and longitudinal strain septal contraction patterns 1 and 2 (aOR: 10.05 [95% CI: 2.82-43.97]; P < 0.001) were associated with CRT response. During a 46-month follow-up (IQR: 42-55 months), survival free from death or HF hospitalization increased with the number of positive criteria (87% for 2, 59% for 1, and 27% for 0). After adjustment for established predictors of outcome in patients receiving CRT, absence of either of the 2 criteria remained associated with a considerable increased risk of death and/or HF hospitalization (adjusted HR: 4.83 [95% CI: 1.84-12.68]; P = 0.001). ConclusionsIn patients with UEC, echocardiographic assessment of EMD may help to select patients who will derive benefit from CRT. (Echocardiography in Cardiac Resynchronization Therapy [Echo-CRT]; NCT02986633)

Right ventricular electromechanical dyssynchrony in adults with repaired Tetralogy of Fallot.

Electromechanical dyssynchrony, manifested by right bundle branch block and regional wall mechanical dysfunction, contributes to inefficient RV function in repaired Tetralogy of Fallot (ToF). This study aims to evaluate the synchronicity of multiple RV walls using two-dimensional multi-plane echocardiography (2D-MPE) in order to augment current understanding of the mechanisms behind RV dyssynchrony. Sixty-nine adult ToF patients [aged 33 (23-45) years; 61% male] and twenty-five matched healthy controls underwent deformational analysis of the RV lateral, anterior, inferior and septal walls following 2D-MPE acquisitions. RV synchronicity was assessed by the intra-RV deformation delay between each basal RV wall and mid-septal segment in addition to mechanical dispersion calculated across four, six and eight segments (MD). All RV wall-septum delays plus MD-4 and MD-6 indices were significantly greater in ToF patients compared to healthy controls (p < 0.001-0.03). In ToF patients, the lateral and anterior RV walls were last to reach peak deformation and anterior wall longitudinal strain was lower (p = 0.001). Post systolic shortening of at least one RV wall segment was identified in 19 (28%) ToF patients. Despite similar ECG characteristics, lateral and anterior wall-septum delays were significantly longer in patients with greater degrees of dyssynchrony (73 [37-108]ms vs. 37 [0-63]ms, p = 0.006; 91 [52-116]ms vs. 41 [1-69]ms, p = 0.013), although RV ejection fraction (RVEF) was not significantly lower. MD-4 and MD-8 indices displayed moderate negative associations with RVEF, strengthened by inclusion of lateral wall longitudinal strain (r = 0.64/0.65; p ≤0.01). RV dyssynchrony in ToF is characterised by electromechanical delays between the lateral, anterior and septal walls, with anterior wall dysfunction likely associated with surgical repair of the RV outflow tract. Prospectively, 2D-MPE may have an emerging role evaluating RV mechanical response to electrical resynchronisation therapy.

Right Ventricular Electromechanical Dyssynchrony and Its Relation to Right Ventricular Remodeling, Dysfunction, and Exercise Capacity in Ebstein Anomaly

Abnormal atrioventricular and intraventricular electrical conduction and dysfunction of the functional right ventricle (fRV) are common in Ebstein anomaly (EA). However, fRV mechanical dyssynchrony and its relation to fRV function are poorly characterized. We evaluated fRV mechanical dyssynchrony in EA patients in relation to fRV remodeling, dysfunction, and exercise intolerance. We retrospectively analyzed data from nonoperated EA patients and age-matched controls who underwent echocardiography, cardiovascular magnetic resonance imaging, and cardiopulmonary exercise testing to quantify right ventricular (RV) remodeling, dysfunction, and exercise capacity. The relation of these to fRV dyssynchrony was retrospectively investigated. Right ventricular mechanical dyssynchrony was defined by early fRV septal activation (right-sided septal flash), RV lateral wall prestretch/late contraction, postsystolic shortening, and intra-RV delay using two-dimensional strain echocardiography. The SD of time to peak shortening among the fRV segments was calculated as a parameter of mechanical dispersion. Thirty-five EA patients (10 of whom were <18years of age) and 35 age-matched controls were studied. Ebstein anomaly patients had worse RV function and increased intra-RV dyssynchrony versus controls. Nineteen of 35 (54%) EA patients had early septal activation with simultaneous stretch and consequent late activation and postsystolic shortening of RV lateral segments. Intra-fRV mechanical delay correlated with fRV end-diastolic volume index (r=0.43, P<.05) and fRV end-systolic volume index (r=0.63, P<.001). The fRV ejection fraction was lower in EA with versus without right-sided septal flash (44.9±11.0 vs 54.2±8.2, P=.012). The fRV mechanical dispersion correlated with the percentage of predicted peak VO2 (r=-0.35, P<.05). In EA, fRV mechanical dyssynchrony is associated with fRV remodeling, dysfunction, and impaired exercise capacity. Mechanical dyssynchrony as a therapeutic target in selected EA patients warrants further study.

My preferred approach to left bundle branch pacing: Lumenless leads.

Right ventricular (RV) pacing results in electromechanical dyssynchrony in the ventricles leading to increased risk for pacing induced cardiomyopathy, heart failure, atrial fibrillation and mortality. Physiologic pacing using His bundle pacing (HBP) or left bundle branch pacing(LBBP) maintains ventricular synchrony and in observational, case-control studies has been shown to reduce the risk for death, heart failure hospitalization or need for upgrade to biventricular pacing when compared to RV pacing1,2,3.

Influence of non-apical permanent pacing on left ventricular systolic impairment

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular apical (RVA) pacing deleterious effects on left ventricular ejection fraction (LVEF) had been demonstrated. Non-apical pacing, such as right ventricular mid-septal (RVMS) and His Bundle pacing, appear as practical alternatives. Our purpose is to evaluate the effect of alternate sites of right ventricular (RV) pacing on left ventricular (LV) function and hemodynamics in patients with bradyarrhythmias. Methods We observed 118 patients (age 58±27 years, 64% men) with AV block III, who underwent permanent dual chamber pacemaker implantation. To 72 patients RV lead has implanted the middle area of RV septum (RVMS) and 46 patients’ RV lead has been implanted traditionally to the right ventricular apex (RVA). Color tissue velocity imaging was performed to analyze time to peak systolic velocity (Ts) in a 12 segment model of the LV for each pacing site. Measurements included standard deviation of time to peak systolic velocity (SD-Ts) for all segments, the maximal difference in Ts between any 2/6 basal (Ts-B), any 2/6 mid segments (Ts-M) and maximal Ts difference between any 2/12 segments (Ts-12). Stroke volume was estimated using Doppler velocity time integral (TVI) in the left ventricular outflow tract (LVOT). QRS width for each site was recorded. Measurements were observed by transthoracic echocardiography and electrocardiography before and 12 months after implantation. Results Ts-12 was significantly higher with RVA - pacing (107 ms, p=0.003) compared to RVMS - pacing (81 ms) sites. SD-Ts were significantly higher with RVA - pacing (38.5 ms, p=0.01) than RVMS - pacing (28.7 ms). QRS duration was the longest for RVA - pacing (157 ms) while significantly shorter RVMS - pacing (115 ms, p&amp;lt;0.001). LVOT VTI was significantly higher for RVMS - pacing than for RVA (p=0.0014) pacing. Conclusions Right ventricular mid-septal pacing may reduce electro-mechanical dyssynchrony compared to RVA pacing and RVMS – pacing to effect better LV function and hemodynamics than RVA pacing in patients with permanent pacemaker implantation.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Single ventricular strain measures correlate with peak oxygen consumption in children and adolescents with Fontan circulation.

Children with a single ventricle post-Fontan palliation are at increased risk of poor outcomes with peak oxygen consumption acting as a surrogate outcome marker. The purpose of this study is to evaluate the relationship between peak oxygen consumption and echocardiographic measures of ventricular function and deformation, including ventricular global longitudinal strain and dyssynchrony, in children and adolescents following Fontan palliation. Patients (age 8-21 years) with single ventricle post-Fontan palliation were prospectively recruited and participated in an echocardiogram, including views optimised for two-dimensional speckle tracking, and a cardiopulmonary exercise test on a cycle ergometer to maximal volitional fatigue. Thirty-eight patients (mean age 13.7 ± 2.3 years) post-Fontan palliation had either a single left ventricular (n = 20), single right ventricular (n = 14), or biventricular (n = 4) morphology. Peak oxygen consumption (24.9 ± 5.6 ml/kg/minute) was correlated with global longitudinal strain (r = -0.435, p = 0.007), a strain discoordination time to peak index (r = -0.48, p = 0.003), and the presence of an electro-mechanical dyssynchrony strain pattern (p = 0.008). On multivariate regression modelling, these three variables were associated with peak oxygen consumption independently of age and sex. The single right ventricular group had evidence of possible diastolic dysfunction by E/e' compared to the single left ventricular and biventricular groups (p = 0.001). Strain analysis measures are correlated with peak oxygen consumption in this cohort of children, adolescents, and young adults following Fontan palliation, suggesting that ventricular mechanics may influence the efficiency of the Fontan circulation.