Left Bundle Branch Block Pattern Research Articles

Cardiac Resynchronization Therapy–Defibrillator Implantation with Shock Lead Placement in the Left Bundle Branch Area by Reshaping Steerable Delivery Sheath: A Case Report

Abstract Background There are few reports of establishing cardiac resynchronization therapy-defibrillator with placing a shock lead directly into the LBBA. Case summary A 76-year-old woman with heart failure due to dilated cardiomyopathy presented to our cardiovascular medicine department. Despite receiving optimal medical therapy, she had New York Heart Association class III heart failure. While her electrocardiogram showed a sinus rhythm with a left bundle branch block pattern (QRS duration, 160 ms) and left ventricular ejection fraction of 21.0%, holter monitoring revealed frequent multifocal ventricular premature beats and non-sustained ventricular tachycardia. Owing to worsening heart failure symptoms, cardiac resynchronization therapy (CRT)-D implantation was performed. As the Agilis HisPro catheter has two 90° deflections, we reshaped its proximal part to the second deflection and added a septal curve, allowing us to screw the shock lead deep into ventricular septum and achieve QRS narrowing of right ventricular pace (114 ms). The time from stimulus to left ventricular activation was 84 ms. Coronary sinus and right atrial leads were placed in conventional manner. Finally, a defibrillation threshold test confirmed a successful treatment with no postoperative adverse events. Discussion Combining left bundle branch area pacing (LBBAP) with coronary sinus (CS) pacing improved prognosis by achieving superior electrical resynchronisation (left bundle branch–optimized CRT: LOT-CRT). However, in the absence of suitable tool for directly placing the shock lead in left bundle branch area (LBBA), it was difficult to establish LOT-CRTD. Herein, we established LOT-CRTD by reshaping Agilis HisPro catheter, which enabled shock lead placement in LBBA.

Impact of non-typical LBBB on CRT response

Abstract Introduction Cardiac resynchronization therapy (CRT) benefits have been established in patients with heart failure and reduced left ventricular ejection fraction (HFrEF) who have a broad QRS and remain symptomatic despite optimized medical therapy. Responders typically are female, with LBBB and broader QRS. It remains uncertain to what extent do patients with non-LBBB QRS complex morphology respond to CRT and also if there are differences among various types of intraventricular conduction delays. Purpose To evaluate the impact of non-typical left bundle branch block (LBBB) on reverser remodeling and clinical events. Methods Single center, observational, retrospective study including patients (pts) who implanted CRT in the context of HFrEF, from 2015 to 2020. Evaluation of QRS morphology analysis was conducted. CRT response was defined by a reduction of LVESV≥15% or an increase in LVEF≥10%. Predictors of CRT response were evaluated with Chi-square and Mann- Whitney analysis. Impact on reverse remodeling and clinical outcomes was performed with Kaplan-Meyer analysis. Results A total of 361 pts were included for analysis, of which 184 had non-typical LBBB. Pts had a mean age of 71±9years old, the majority of pts were female (61%), and almost half were ischemic (47.8%). EGC evaluation prior to CRT implantation, revealed an atypical LBBB in 83 (45.1%) pts, typical RBBB in 23 (12.5%) pts, atypical RBBB 94.(9%) pts and nonspecific intraventricular conduction delay in 69 (37.5%) pts. During a mean time of follow-up of 2.9 ±2.4years, 33 pts (18%) had hospitalizations due to HF and 68 (37%) died. In this cohort, 78 pts (42.4%) were deemed as responders, who presented a better clinical outcome when compared to non-responders (p < 0.001, HR 2.629 [95% CI 1.635-4.225]. There was no difference among the four types of intraventricular conduction analyzed in respect to degree of CRT response – figure 1. Regarding clinical events during follow-up, there was once again no significant difference among the different patterns of non-typical LBBB– figure 2. In this subset population we found no independent predictors of CRT response, although non-responders were significantly older than responders (72±8 vs 69±10 years-old (p=0.016). Conclusion Although pts with non-typical LBBB morphology display a lower therapy response to CRT than reported for LBBB pts, the rate of response is not negligible and represents a protective factor for clinical outcomes. Different types of intraventricular conduction delay present no difference regarding long- term prognosis or reverse remodeling.Survival according to CRT response

Longitudinal comparison of dyssynchrony correction and strain improvement by conduction system pacing: LEVEL-AT trial secondary findings.

Our purpose was to compare echocardiographic dyssynchrony correction and strain improvement by conduction system pacing (CSP) vs. biventricular pacing (BiVP) as a marker of contractility improvement during one-year follow-up. A treatment-received analysis was performed in patients included in the LEVEL-AT trial (NCT04054895), randomized to CSP or BiVP, and evaluated at baseline (ON and OFF programming) and at 6 and 12 months (n = 69, 32% women). Analysis included intraventricular (septal flash), interventricular (difference between left and right ventricular outflow times), and atrioventricular (diastolic filling time) dyssynchrony and strain parameters (septal bounce, global longitudinal strain [GLS], left bundle branch block pattern and mechanical dispersion).Baseline left ventricular ejection fraction (LVEF) was 27.5 ± 7% and left ventricular end-systolic volume (LVESV) was 138 ± 77 ml, without differences between groups. Longitudinal analysis showed LVEF and LVESV improvement (p < 0.001), without between-group differences. At 12-month follow-up, adjusted mean LVEF was 46% with CSP (95%CI 42.2%, 49.3%) vs. 43% with BiVP (95%CI 39.6%, 45.8%) (p = 0.31) and LVESV was 80 ml (95%CI 55.3 ml, 104.5 ml) vs. 100 ml (95%CI 78.7 ml, 121.6 ml), respectively (p = 0.66).Longitudinal analysis showed a significative improvement of all dyssynchrony parameters and GLS over time (p < 0.001), without differences between groups. Baseline GLS significantly correlated with LVEF and LVESV at 12-month follow-up. CSP and BiVP provided similar dyssynchrony and strain correction over time. Baseline global longitudinal strain correction predicted ventricular remodeling at 12-month follow-up.

LEFT BUNDLE BRANCH BLOCK AND ACUTE CORONARY SYNDROME: WHAT IS THE ROLE OF MODIFIED SGARBOSSA–SMITH CRITERIA AND THE WELLENS‘ PATTERN?

Abstract A 55–year–old man presented to the emergency room with intermittent chest pain that started the day before. His medical history included hypertension, and dyslipidemia. The initial electrocardiogram (ECG) showed sinus rhythm (75 bpm) with pre–existing left bundle branch block (LBBB), without modified Sgarbossa–Smith criteria, despite the hyperacute appearance of T waves in V2–V4 (Fig. 1). Additionally, there were alterations in ventricular repolarization in the lateral region, morphologically not fully justifiable by the mentioned conduction delay. Echocardiography revealed normal left and right ventricular systolic function and no valvular abnormalities. Laboratory tests showed a pathological release of myocardial necrosis enzymes, with a typical rise–and–fall curve (10 pg/mL, 100 pg/mL, 200 pg/mL; normal range: 1.7–34.2 pg/mL). Therefore, the patient was admitted to the intensive cardiac care unit (ICCU) with a working diagnosis of non–ST–segment elevation myocardial infarction (NSTEMI). There were no recurrent angina episodes or signs/symptoms of heart failure on physical examination. During hospitalization, ECG and echocardiography were repeated. The follow–up ECG (12 hours after admission) showed persistent LBBB with biphasic T waves in leads V2–V5 with slight negative deflection at the end. This T wave abnormality can be interpreted as Wellens’ ECG Type A (Fig. 3A). The echocardiogram remained unchanged. Consequently, the catheterization lab was activated for urgent coronary angiography. The examination revealed subocclusion of the mid–segment of the left anterior descending artery (LAD). A drug–eluting stent was deployed in the culprit lesion (Fig. 2), restoring coronary flow completely (TIMI Flow 3). The subsequent hospital stay proceeded without complications. The ECG performed before discharge showed a typical LBBB, with normalization of T waves in precordial leads (Fig 3B). The presented case is about ECGs containing a pre–existing LBBB pattern in a patient with chest pain. The modified Sgarbossa–Smith criteria were not met in either the first recorded ECG or the second, whereas Wellens’ signs were detectable. Wellens’ syndrome can be diagnosed in a case of LBBB and help detect a high–grade LAD stenosis even if modified Sgarbossa–Smith criteria are not met.

Discrimination between ventricular tachycardia and wide-QRS preexcited tachycardia.

To develop a new algorithm to differentiate ventricular tachycardia (VT) from preexcited tachycardia (pre-ET) according to left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. This study included 67 electrocardiograms (ECGs) with VT and 63 ECGs with pre-ET, collected from our hospital and through PubMed. Of those, 64 were allocated to the derivation cohort and the rest to the validation cohort. The diagnoses of the ECGs were confirmed using an electrophysiological study. Parameters and classifiers from prior algorithms along with the propagation speeds in the early portion of the QRS complex (initial deflection index) in leads V1, V6, aVR, II, and III were manually measured. The performance of the new algorithm was compared with that of prior algorithms. The initial deflection index in lead III was the strongest predictor of pre-ET in LBBB-pattern wide-QRS tachycardia (p = 0.003, AUC 0.805). The initial deflection index in lead V1 was the most powerful predictor of pre-ET in RBBB-pattern wide-QRS tachycardia (p = 0.001, AUC 0.848). Compared to earlier algorithms, those using the initial deflection indexes: lead III in LBBB patterns (cutoff value >0.3) and lead V1 in RBBB patterns (cutoff value ≤0.48), demonstrated superior performance in screening VT, with AUC values of 0.828. The initial deflection indexes proved effective as discriminators between VT and pre-ET in the validation cohort. In LBBB-pattern wide-QRS tachycardia, the early propagation speed of pre-ET was faster than that in VT. Conversely, in RBBB-pattern wide-QRS tachycardia, it was slower.

Feasibility of Conduction System Pacing in Patients with Baseline Bundle Branch Block-A Single-Center Mid-Term Follow-Up Study.

The primary prerequisite for a successful conduction system pacing (CSP) procedure is the integrity of the conduction system, which may be impaired if a baseline bundle branch block (BBB) is present. This study aimed to evaluate the feasibility and mid-term performance of permanent CSP in patients with baseline BBB and to compare the results between left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. A total of 101 patients with typical BBB and an attempt at CSP were retrospectively reviewed. Procedural characteristics, pacing, sensing parameters, and complications at baseline and after a mid-term follow-up were analyzed. The global procedural success for CSP was 93%. His bundle pacing (HBP) had a significantly lower success rate than left bundle branch area pacing (LBBAP) (50.5% vs. 86%). The paced QRS duration was significantly narrower with HBP. The pacing and sensing thresholds were significantly better with LBBAP. Procedural complications occurred only in the LBBAP group (two acute perforations in the LV cavity and one acute chest pain during lead fixation) without long-term sequelae. The HBP and the LBBAP procedural success rates were higher in the RBBB versus the LBBB group (62.5% vs. 44.9% and 100% vs. 81.5%, respectively). Baseline QRS duration, atrial volumes, and right ventricular diameters were significantly associated with HBP procedural failure. The follow-up pacing and sensing thresholds were similar to the baseline values for all pacing methods and BBB morphology. Only one device-related complication leading to pacing interruption was recorded. In patients with bundle branch blocks, CSP is a feasible procedure associated with a high success rate, stable pacing and sensing parameters, and low complication rates over a mid-term follow-up.

Differentiating Origins of Outflow Tract Ventricular Arrhythmias: The Correction of Transitional Zone Index Is Not Superior to the Original One

Introduction: Our team once proposed a correction of transitional zone index (CTZI) based on the transitional zone index (TZI) in view of achieving a more precise prediction of outflow tract ventricular arrhythmia (OTVA). The predictive accuracy of these two electrocardiogram (ECG) algorithms has not been validated and compared. The purpose of this study was to compare the predictive accuracy of TZI and CTZI in a much larger population with idiopathic OTVA. Methods: The predictive accuracy of TZI and CTZI was compared in 695 individuals with idiopathic premature ventricular complex or ventricular tachycardia which exhibited a left bundle branch block pattern and inferior axis QRS morphology. Receiver operating characteristic curve analysis, decision curve analysis, and calibration curve were used to compare the predictive accuracy of TZI and CTZI. Results: TZI and CTZI manifested the similar area under the curve. While a TZI of <0 predicted a left ventricular outflow tract (LVOT) origin with a high specificity of 88.2% but a low sensitivity of 67.1%, a CTZI of <0 yielded a high sensitivity of 84.3% but a low specificity of 59.5% in the overall analysis. Similar results were yielded in the sub-analysis of participants with a precordial transition occurring at lead V3. In the sub-analysis of participants with a TZI = 0, CTZI demonstrated a bit higher but not satisfactory predictive accuracy than TZI. Conclusion: Based on the scientific spirit of self-criticism and seeking truth from facts, our team disproves the correction of TZI proposed previously.

High frame rate speckle tracking echocardiography to visualize the mechanical activation sequence of the left ventricle

Abstract Background Cardiac arrhythmias are a known cause of morbidity and mortality, with catheter ablation being an effective treatment. In order to detect the focal source or the re-entrant circuit of the arrhythmia, i.e. the ablation target, current practice includes performing an electrophysiological study. This technique is invasive, with increased patient related risk and variable success rate. Conversely, echocardiography could be used to determine the correct ablation target. High frame rate (HFR) ultrasound has a temporal resolution adequately high to detect the onset of myocardial deformation and could assist the accurate localisation of the arrhythmia source. Purpose To test whether HFR speckle tracking echocardiography (STE) can be used to create cardiac mechanical activation maps. Methods 18 healthy volunteers (HV) (age 30±6y; 69 %males) and 12 heart failure patients treated with cardiac resynchronisation therapy (CRT) (age 69±10y; 75 %males) were included. All participants were scanned with a research HFR ultrasound scanner (∼849fps) and the 3 standard apical views were acquired. Patients were scanned with CRT on and after turning CRT off, in order to allow intrinsic ventricular conduction. Data from one CRT patient were acquired by temporarily altering the pacing pole of the CRT LV lead. All patients had a left bundle branch block (LBBB) pattern of native activation on the surface ECG. For each view, a manually placed contour was tracked during the cardiac cycle by a custom-made 2D HFR STE algorithm; the contours were divided in a standard 16 segment model and segmental strain rate (SR) curves were computed and used to measure the temporal distance between electrical and mechanical activation (i.e. distance between the beginning of QRS and the first positive to negative zero crossing in the SR curve). Finally, an activation map for each subject was created by placing the extracted timings in the middle of the corresponding segment of a bull’s-eye plot and interpolating values between them. Results Tracking was feasible in 94% of the segments; SR curves showed a physiological pattern (Fig. 1A). For the HV, mechanical activation started from mid anteroseptal (72%) or mid inferoseptal (28%) segment at 23±5ms, spreading to basal posterolateral segment at 49±8ms from the start of QRS, in all but one case, where activation ended at basal inferoseptal segment (Fig. 1B). During CRT off, septal wall was activated 31±9ms and lateral wall 74±20ms after the beginning of QRS (p&amp;lt;0.01) (Fig. 1C), whereas during CRT on, septal wall was activated 41±11ms and lateral wall 38±7ms after the beginning of QRS (p=0.3) (Fig. 1D). Changing the pacing pole of the LV lead in one CRT patient also changed the start of mechanical activation in the lateral wall (Fig. 2). Conclusion Our findings comply with left ventricular activation as described in the literature and show that HFR STE could be a useful tool in defining the ablation target for arrhythmia treatment.

Abstract 15650: Recovery of Cardiomyopathy Following Accessory Pathway Ablation

Background: Wolf-Parkinson-White (WPW) can cause significant arrhythmia in addition to left ventricular (LV) dessynchrony and cardiomyopathy, which may be reversible by accessory pathway ablation. Case: A 21-year-old female athletics major college student presents with dyspnea, fatigue and occasional palpitations associated with dizziness. Electrocardiogram (EKG) revealed WPW with left bundle branch block pattern suggestive of right-sided bypass tract (panel A). Transthoracic echocardiogram (TTE) revealed LV ejection fraction (LVEF) 35 - 40% and significant interventricular dessynchrony on M-mode (panel B). Decision-making: It was felt that her symptoms and LV dysfunction are due to QRS widening and possibly arrhythmia caused by the bypass tract, and that ablation is warranted. Electrophysiology study 3-D map revealed 2 insertion points of the bypass tract along the tricuspid annulus (panel C). Ablation was performed initially along the inferior tricuspid annulus, leading to QRS complex narrowing with a change in the delta wave axis. Another activation site was mapped separately to the anterolateral tricuspid annulus; ablation at this site eliminated pre-excitation altogether. Post procedure EKG revealed normalization of the PR interval and diffuse T wave abnormalities likely due to cardiac memory (panel D). Follow-up in 6 weeks revealed an LVEF of 60 - 65% and normal wall motion on TTE with improvement of her symptoms; she was cleared to resume sports. Conclusion: WPW can be associated with significant cardiomyopathy and heart failure due both to arrhythmia and marked LV dessynchrony, which may be reversed by radiofrequency ablation.

Triggers of Ventricular Fibrillation in Patients With Inferolateral J-Wave Syndrome

BackgroundThere are few data on ventricular fibrillation (VF) initiation in patients with inferolateral J waves. ObjectivesThis multicenter study investigated the characteristics of triggers initiating spontaneous VF in inferolateral J-wave syndrome. MethodsA total of 31 patients (age 37 ± 14 years, 24 male) with spontaneous VF episodes associated with inferolateral J waves were evaluated to determine the origin and characteristics of triggers. The J-wave pattern was recorded in inferior leads in 11 patients, lateral leads in 3, and inferolateral leads in 17. ResultsThe VF triggers (n = 37) exhibited varying QRS durations (176 ± 21 milliseconds, range 119-219 milliseconds) and coupling intervals (339 ± 46 milliseconds, range 250-508 milliseconds) with a right (70%) or left (30%) bundle branch block (BBB) pattern. Trigger patterns were associated with J-wave location: left BBB triggers with inferior J waves and right BBB triggers with lateral J waves. Electrophysiologic study was performed for 22 VF triggers in 19 patients. They originated from the left or right Purkinje system in 6 and from the ventricular myocardium in 10 and were undetermined in 6. Purkinje vs myocardial triggers showed distinct electrocardiographic characteristics in coupling interval and QRS-complex duration and morphology. Abnormal epicardial substrate associated with fragmented electrograms was identified in 9 patients, with triggers originating from the same region in 7 patients. Catheter ablation resulted in VF suppression in 15 patients (79%). ConclusionsVF initiation in inferolateral J-wave syndrome is associated with significant individual heterogeneity in trigger characteristics. Myocardial triggers have electrocardiographic features distinct from Purkinje triggers, and their origin often colocalizes with an abnormal epicardial substrate.

ECG characteristics of “true” left bundle branch block: Insights from transcatheter aortic valve–related LBBB and His-Purkinje conduction system pacing–correctable LBBB

Left bundle branch block (LBBB) pattern on the electrocardiogram includes patients with both complete conduction block in the His-Purkinje system as well as nonspecific left ventricular conduction delay without discrete block. The purpose of this study was to characterize electrocardiographic morphological features of LBBB patterns in patients with (1) LBBB after transcatheter aortic valve replacement (TAVR) and (2) LBBB correctable by conduction system pacing (CSP). Consecutive patients with post-TAVR (n = 123) or CSP-correctable LBBB (n = 58) from 2 centers were included in this retrospective evaluation. QRS durations as well as detailed morphological features, including notching and slurring, of QRS complexes in leads I, aVL, V1, V2, V5, and V6 and in all 3 inferior leads were recorded. The mean age of the entire cohort was 78.3 ± 10.1 years, with 48% of the cohort being male(87/181). In the CSP-correctable group (n = 58), 14 (24.1%) underwent His-bundle pacing and 44 (75.9%) left bundle branch area pacing. A total of 17 of 181 (9.4%) of the combined cohort failed to completely meet the Strauss criteria. QRS morphology in lead V1/V2 was always either rS or QS, and there were no q/Q waves noted in lead V5/V6. Although dominant R waves were seen in leads I and aVL of 176 of 181 (97.2%), q/Q waves were present in only 21 of 181 (11.6%). Importantly, notched or slurred QRS complexes were identified in at least 1 lead of 4 leads I, aVL, V5, and V6 in 181 of 181 (100%). Strauss criteria and QRS notching are highly prevalent in LBBB after TAVR and in LBBB correctable by CSP.

Bilateral Bundle Branch Block.

Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is uncommon and underrecognized may exist that has features and pathophysiology of both: bilateral bundle branch block (BBBB). This unusual form of bundle branch block exhibits an RBBB pattern in lead V1 (terminal R wave) and an LBBB pattern in leads I and aVL (absence of S wave). This unique conduction disorder may confer an increased risk of adverse cardiovascular events. BBBB patients may be a subset of patients that respond well to cardiac resynchronization therapy.

Utility of the Inferior Axis and Left Bundle Branch Block Pattern for Categorization of Patients With Premature Ventricular Complexes Before Catheter Ablation

Utility of the Inferior Axis and Left Bundle Branch Block Pattern for Categorization of Patients With Premature Ventricular Complexes Before Catheter Ablation

High frame rate speckle tracking echocardiography for the mapping of cardiac mechanical activation sequence

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): KU Leuven. Background Cardiac arrhythmias are a leading cause of worldwide morbidity and mortality, with catheter ablation being an effective treatment. Current clinical practice includes performing an electrophysiological study in order to detect the focal source or the re-entrant circuit of the arrhythmia, i.e. the ablation target. This technique is invasive, with increased patient related risk and variable success rate. Conversely, echocardiography could be used to determine the correct ablation target. Indeed, high frame rate (HFR) ultrasound provides an adequately high temporal resolution, has proven helpful in detecting the onset of myocardial deformation and could be used for accurate localization of the arrhythmia sources. Purpose To test whether HFR speckle tracking echocardiography (STE) can be employed to construct cardiac mechanical activation maps. Methods 16 healthy volunteers (age: 30±6y; 69% males) and 11 heart failure patients treated with cardiac resynchronisation therapy (CRT) (age: 69±10y; 73% males) were included. All participants were scanned with a research high frame rate ultrasound scanner (frame rate: 848±101fps) and apical 4-, 2- and 3-chamber views were acquired. Patients were scanned with CRT on and after turning the device off, in order to allow native ventricular conduction. All patients had a left bundle branch block (LBBB) pattern of intrinsic activation on the surface ECG. For each apical view, a manually placed contour was tracked during the cardiac cycle by a custom-made 2D HFR STE algorithm; the contours were divided in a standard 16 segment model and segmental strain rate (SR) curves were computed and used to measure the temporal distance between electrical and mechanical activation (i.e. distance between the beginning of QRS and the first zero crossing in the SR curve representing the onset of segmental shortening). Finally, an activation map for each subject was created by placing the extracted timings in the middle of the corresponding segment of a bull’s-eye plot and interpolating values between them. Results Tracking was feasible in 96% of the segments; extracted curves showed a physiological pattern (Fig. 1A). For the healthy participants, mechanical activation started from the mid-anteroseptal (69%) or mid-inferoseptal (31%) segment at 22±5ms, spreading to the basal posterolateral segment at 50±8ms from the start of QRS, in all but two cases, where activation ended in the basal inferoseptal and basal inferior segment respectively (Fig. 1B). During CRT off, the septal wall was activated 31±9ms and the lateral wall 73±20ms after the beginning of QRS (p&amp;lt;0.01) (Fig. 1C), whereas during CRT on, the septal wall was activated 40±11ms and the lateral wall 37±7ms after the beginning of QRS (p = 0.3) (Fig. 1D). Conclusion Our findings comply with left ventricular activation as described in the literature and show that HFR STE could be a useful tool in defining the ablation target for arrhythmia treatment.

Mid-term follow-up of atrioventricular node ablation and conduction system pacing without a ventricular backup lead in atrial fibrillation-induced tachycardiomyopathy - a single-center experience

Abstract Funding Acknowledgements Type of funding sources: None. In the permanent form of atrial fibrillation (AF), ablation is not recommended or has failed and the only option is rate control. The most effective rate control strategy is atrioventricular node (AVN) ablation, but this renders the patient pacing-dependent. Several observational studies have shown that both His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), provide a narrower QRS complex and a more synchronous ventricular activation compared to right ventricular pacing. Current guidelines recommend placing a ventricular backup lead as a safety measure. We present our mid-term follow-up data on the feasibility of AVN ablation and physiological pacing without a ventricular backup lead in patients with tachycardiomyopathy due to rapidly conducted permanent AF. MATERIAL AND METHODS A total of 25 patients with permanent AF and HF and rate control failure with AVN-blocking drugs, that underwent physiological pacing and AVN ablation at our institution, were included in this retrospective review. During the procedure, HBP was the first option, followed by LBBAP if the His bundle was not captured at a threshold below 2.5V at 1 ms. The lead was connected to a single chamber pacemaker, without a backup pacing lead. In the same setting, using a femoral vein approach, a 4-mm tip ablation catheter was used to perform AVN ablation. Patient and procedural characteristics were recorded as well as the electrical parameters and complications at the follow-up visits. Results The mean age of the patients was 69 ± 12.4 years and 64% were males. The heart rate was 133±20.43 bpm and the ejection fraction was 28.84±9.02 %. 17 patients had normal QRS complex, 3 had right bundle branch block and 5 had left bundle branch block patterns. HBP was successful in 9 patients (36%) and LBBAP in 16 patients (64%). In patients with a baseline-wide QRS, physiological pacing significantly reduced the QRS duration (135.25±17.58 vs. 159±32.38 ms, p=0.04). The paced QRS complex was significantly narrower in HBP than LBBAP (95.67±14.37 vs. 129.88±17.46 ms, p&amp;lt;0.001). There was a significantly lower pacing threshold for LBBAP (0.77±0.3 V at 1 ms vs. 0.87±0.72 V at 0.4 ms, p&amp;lt;0.05) and better sensitivity for LBBAP (6.23±4.56 mV vs. 10.2±5.19 mV, p=0.66). The fluoroscopy time was non-statistically different between HBP and LBBAP (13.21±15.47 min vs. 18.72±12.95 min, p=0.35). AV node ablation was successful in all patients. The mean follow-up period was 524±110.2 days. 11 patients became pacemaker-dependent. There was no significant difference in pacing thresholds for both LBBAP (0.67±0.27 V at 0.4 ms, p=0.24) and HBP (0.87±0.56 V at 1 ms, p=0.485) patients and there was no recurrence in AV node conduction. No lead dislodgements were recorded. Conclusions AVN ablation and physiological pacing is feasible and safe without the need for a backup ventricular pacing lead, thus minimizing the risks and costs associated with a higher lead burden.

Usefulness of the synthesized 18-lead ECG in premature ventricular contractions from near the HIS bundle.

Isolated premature ventricular complexes (PVCs) are the most common arrhythmias observed in patients even if without structural heart disease.1 Although most PVCs originate from the right ventricular outflow tract (RVOT), there are some PVCs that originate near the HIS bundle.2 The synthesized 18-lead ECG consists of right-sided thoracic (V3R, V4R, V5R) and dorsal (V7, V8, V9) ECG leads derived from a mathematical calculation of the 12-lead ECG, and the detailed mathematical formula is shown in Figure 1. The synthesized 18-lead ECG has been reported to be effective for PVCs of an RVOT origin, but the rest remains to be elucidated.3 The aim of this study was to investigate the characteristics of the synthesized 18-lead ECG in patients with PVCs originating from near the HIS bundle. The synthesized 18-lead ECGs of 13 consecutive patients who underwent radiofrequency catheter ablation (RFCA) of idiopathic PVCs from near the HIS bundle at the Japan Community Healthcare Organization Osaka Hospital, Osaka General Medical Center, and Nara Prefectural Seiwa Medical Center from January 2018 to December 2020 were included in this retrospective analysis. The origin of the PVCs was identified by a cardiologist using a 3D mapping system (CARTO 3: Biosense Webster Inc or EnSite: Abbott Medical Inc). We analyzed the QRS morphology pattern of the synthesized 18-lead ECG analyzed in those patients. This study was approved by the Ethics Committee of each hospital in accordance with the Declaration of Helsinki. The synthesized 18-lead ECG and ECG characteristics in 13 patients with PVCs from near the HIS bundle are shown in Figure 2 and Table 1. The mean QRS duration of the ECG was 142.5 ± 26.9 ms. In 12 of 13 patients, a left bundle branch block pattern (92.3%) was present, and 11 of 13 patients had inferior axis deviation (84.6%). Regarding the right-sided chest leads of the synthesized 18-lead ECG, in all patients, a QS pattern in lead V5R (100%) was observed, and in 12 of 13 patients, a QS pattern in leads V3R, V4R, and V5R (92.3%) was present. A comparison showed that the synthesized ECGs recorded during sinus rhythm and during PVCs were not consistent, as shown in Table 2. Several studies have shown that identifying PVCs originating from the vicinity of the ventricular septum remains complicated,4 and it is difficult to identify the origin of PVCs originating from near the HIS bundle based on the characteristics of the 12-lead ECG. Noteworthy among our results was that there was a QS pattern in lead V5R in 100.0%. Igarashi et al reported that in the synthesized 18-lead ECG recorded by pace mapping in the outflow tract, a QS pattern in lead V5R was observed in about 80% at the right coronary cusp (RCC), about 20% in the posterior RVOT, and nothing at the other sites.3 Combining the above study3 with our results, a QS pattern in lead V5R might have been specific to PVCs originating from near the HIS bundle and RCC. QRS morphology changes after RFCA are often observed in patients with idiopathic PVCs.5 In such cases, the use of the synthesized 18-lead ECG's right-sided chest leads may assist in the re-mapping process. Regarding the mechanism of the QS pattern in lead V5R, in general the HIS bundle is anatomically closer to the RCC, and electrical conduction may propagate with a vector away from the right-sided chest leads such as lead V5R. Based on the characteristics of the ECG, only case 7 was considered to have a PVC from the HIS bundle. An identification of PVCs originating from near the HIS bundle or from the HIS bundle was attempted based on the characteristics of the synthesized ECG, but was not possible due to an insufficient number of cases. Although a 3D mapping system was used in this study, the distance between the HIS bundle and the ablation site was not measured, and it was considered necessary to include the distance in future studies. A QS pattern recorded in lead V5R of the synthesized 18-lead ECG was characteristic of PVCs originating from near the HIS bundle. This observation might assist in identifying the origin of PVCs during RFCA. H Kida, R Nakanishi, and N Ogasawara participated in the design of the study and coordination and helped draft the manuscript. All authors read and approved the final manuscript. We would like to express our gratitude to Mr. John Martin for his linguistic revision of the manuscript. All authors declare no conflicts of interest associated with this manuscript. This study was approved by the Ethics Committee of Japan Community Healthcare Organization Osaka Hospital, Osaka General Medical Center, and Nara Prefectural Seiwa Medical Center in accordance with the Declaration of Helsinki. Since this study was a retrospective study, we used the opt-out system according to the ethics guidelines on human medical research by the Japanese government.

Electrocardiographic and electrophysiological characteristics of ventricular arrhythmias from the right bundle branch of the moderator band

There are little data on ventricular arrhythmias (VAs) originating from the right bundle branch (RBB) of the moderator band (MB) (MB-RBB VAs) in a cohort of patients. The purpose of this study was to investigate the electrocardiographic and electrophysiological characteristics of MB-RBB VAs. Sixteen patients with MB-RBB VAs and 5 patients with right ventricular (RV) anterior papillary muscle (APM) VAs (RV-APM VAs) were studied under the guidance of intracardiac echocardiography. The MB-RBB VAs group demonstrated a typical left bundle branch block pattern with left superior axis deviation and a narrower QRS complex during VAs (P < .001) as compared with the RV-APM VAs group. Furthermore, the MB-RBB VAs group had a shorter rS interval, a sharper slope of the S wave downstroke without notching in leads V1 and V2, and a shorter r wave duration in lead V2. A leading RBB potential at the target during VAs was observed for all patients in the MB-RBB VAs group, which was also present during sinus rhythm for all patients, except for 2 with RBB block at baseline. Ablation of the leading RBB potential effectively eliminated the arrhythmia. In the RV-APM VAs group, no Purkinje potential at the target was identified in any patient during VAs. QRS morphology of MB-RBB VAs is characterized by a typical left bundle branch block pattern with a relatively narrow QRS complex, short r wave and rS durations, and a sharp S wave downstroke without notching in leads V1 and V2. Mapping and ablation of the leading RBB potential are effective in eliminating VAs.

Exploratory use of intraprocedural transesophageal echocardiography to guide implantation of the leadless pacemaker.

Fluoroscopy is the standard tool for transvenous implantation of traditional and leadless pacemakers (LPs). LPs are used to avoid complications of conventional pacemakers, but there still is a 6.5% risk of major complications. Mid-right ventricular (RV) septal device implantation is suggested to decrease the risk, but helpful cardiac landmarks cannot be visualized under fluoroscopy. Transesophageal echocardiography (TEE) is an alternative intraprocedural imaging method. The purpose of this study was to explore the spatial relationship of the LP to cardiac landmarks via TEE and their correlations with electrocardiographic (ECG) parameters, and to outline an intraprocedural method to confirm mid-RV nonapical lead positioning. Fifty-six patients undergoing implantation of LP with TEE guidance were enrolled in the study. Device position was evaluated by fluoroscopy, ECG, and TEE. Distances between the device and cardiac landmarks were measured by TEE and analyzed with ECG parameters with and without RV pacing. Mid-RV septal positioning was achieved in all patients. TEE transgastric view (0°-40°/90°-130°) was the optimal view for visualizing device position. Mean tricuspid valve-LP distance was 4.9 ± 0.9 cm, mean pulmonary valve-LP distance was 4.2 ± 1 cm, and calculated RV apex-LP distance was 2.9 ± 1 cm. Mean LP paced QRS width was 160.8 ± 28 ms and increased from 117.2 ± 34 ms at baseline. LP RV pacing resulted in left bundle branch block pattern on ECG and 37.8% QRS widening by 43.5 ± 29 ms. TEE may guide LP implantation in the nonapical mid-RV position. Further studies are required to establish whether this technique reduces implant complications compared with conventional fluoroscopy.

The Primary Alteration of Ventricular Myocardium Conduction: The Significant Determinant of Left Bundle Branch Block Pattern.

Intraventricular conduction disturbances (IVCD) are currently generally accepted as ECG diagnostic categories. They are characterized by defined QRS complex patterns that reflect the abnormalities in the intraventricular sequence of activation that can be caused by pathology in the His-Purkinje conduction system (HP) or ventricular myocardium. However, the current understanding of the IVCD's underlying mechanism is mostly attributed to HP structural or functional alterations. The involvement of the working ventricular myocardium is only marginally mentioned or not considered. This opinion paper is focused on the alterations of the ventricular working myocardium leading to the most frequent IVCD pattern-the left bundle branch block pattern (LBBB). Recognizing the underlying mechanisms of the LBBB patterns and the involvement of the ventricular working myocardium is of utmost clinical importance, considering a patient's prognosis and indication for cardiac resynchronization therapy.

The R-S difference index: A new electrocardiographic method for differentiating idiopathic premature ventricular contractions originating from the left and right ventricular outflow tracts presenting a left bundle branch block pattern.

Introduction: Differentiating idiopathic premature ventricular contractions (PVCs) originating from the right and left ventricular outflow tracts with a left bundle branch block (LBBB) morphology is relevant to catheter ablation planning and important for lowering the risk of complications. This study established a novel electrocardiographic (ECG) criterion to discriminate PVCs originating from the septum of the right ventricular outflow tract (s-RVOT) and those originating from the aortic sinus cusp of the left ventricular outflow tract (LVOT-ASC). Methods: A total of 259 patients with idiopathic PVCs originating from ventricular outflow tract with a LBBB pattern who underwent successful catheter ablation were retrospectively included. Among them, the PVCs originated from the s-RVOT in 183 patients and from the LVOT-ASC in 76 patients. The surface ECGs of the PVCs and sinus beats were analyzed using an electronic caliper. The R-S difference index in the precordial leads was calculated as V2R + V3R + V4R − V1S. Results: PVCs originating from both the s-RVOT and LVOT-ASC displayed an inferior axis (dominant R waves in leads II, III, and aVF). Compared with the s-RVOT group, the R-wave amplitudes on leads II, III, and aVF were significantly larger in the LVOT-ASC group (p < 0.001, p < 0.003, and p < 0.001, respectively). Compared to the LVOT-ASC group, the s-RVOT group showed smaller R-wave amplitudes on leads V1–V6 (p = 0.021, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively) and larger S-wave amplitudes on leads V1–V3 (p < 0.001, p < 0.001, and p < 0.001, respectively). Lead V3 was the most common transitional lead in both groups. Analysis of the receiver operating characteristic curve showed that the R-wave amplitude on lead V3 had the largest area under the curve (AUC) of 0.856 followed by the R-wave amplitudes on leads V4 (0.834) and V2 (0.806). The AUC of the R-S difference index was 0.867. An R-S difference index greater than 20.9 predicted an LVOT-ASC origin with 73.7% sensitivity and 86.3% specificity. This index is superior to previous criteria in differentiating PVCs with LBBB morphology and inferior axis originating from s-RVOT vs. LVOT-ASC. Conclusions: The R-S difference index in precordial leads is a useful new ECG criterion for distinguishing LVOT-PVCs from RVOT-PVCs with LBBB morphology.