Right Bundle Branch Block Configuration Research Articles

Electrocardiographic characteristics of right-bundle-branch-block premature ventricular complexes predicting absence of left ventricular scar in athletes with apparently structural normal heart.

Left ventricular scar is an arrhythmic substrate that may be missed by echocardiography and diagnosed only by cardiac magnetic resonance (CMR), which is a time-consuming and expensive imaging modality. Premature ventricular complexes (PVCs) with a right-bundle-branch-block (RBBB) pattern are independent predictors of late gadolinium enhancement (LGE) but their positive predictive value is low. We studied which electrocardiographic features of PVCs with an RBBB pattern are associated with a higher probability of the absence of an underlying LGE. The study included 121 athletes (36 ± 16 years; 48.8% men) with monomorphic PVCs with an RBBB configuration and normal standard clinical investigations who underwent CMR. LGE was identified in 35 patients (29%), predominantly in those with PVCs with a superior/intermediate axis (SA-IntA) compared to inferior axis (IA) (38% vs. 10%, P = 0.002). Among patients with SA-IntA morphology, the contemporary presence of qR pattern in lead aVR and V1 was exclusively found in patients without LGE at CMR (51.0% vs. 0%, P < 0.0001). Among patients with IA, the absence of LGE correlated to a narrow ectopic QRS (145 ± 16 vs. 184 ± 27 msec, P < 0.001). Among athletes with apparently idiopathic PVCs with a RBBB configuration, the presence of a concealed LGE at CMR was documented in 29% of cases, mostly in those with a SA-IntA. In our experience, the contemporary presence of qR pattern in lead aVR and V1 in PVCs with RBBB/SA-IntA morphology or, on the other hand, a relatively narrow QRS in PVCs with an IA, predicted absence of LGE.

Electrocardiographic morphology during left bundle branch area pacing: Characteristics, underlying mechanisms, and clinical implications.

In this study, we investigated the characteristics and underlying mechanisms of the electrocardiographic (ECG) morphology during left bundle branch area pacing (LBBAP), which have not been systematically described. Patients with indications for permanent cardiac pacing underwent LBBAP attempts. The ECGs of patients with confirmed left bundle branch (LBB) capture were compared with those of individuals with right bundle branch block (RBBB) on 12-lead ECG. Intracardiac electrograms recorded during implantation were analyzed in all patients who underwent pacing. LBBAP was successfully achieved in 87.5% (56/64) of patients. The QRS morphologies in lead V1 during LBBAP, which typically demonstrated Qr (60.7%), qR (19.6%), rSR' (7.1%), or QS (12.5%) patterns, differed from those of native RBBB, which featured rsR' (57.5%), M shape (23.7%), or monophasic R patterns (18.7%). The terminal R' wave duration in lead V1 was significantly shorter during LBBAP than during native RBBB (51 ± 12ms vs 85 ± 19ms, p<0.001). LBB potentials were recorded in 66.1% (37/56) of the LBBAP patients. No significant differences in ECG characteristics were found between LBBAP with and without recorded LBB potentials. The presence of bundle branch block during LBBAP significantly prolonged QRS duration, R wave peak time, and terminal R' wave duration in lead V1 . LBBAP-ECG patterns are characterized by a shorter terminal R' wave duration in lead V1 compared with that of native RBBB configurations. Bundle branch conduction integrity has an impact on ECG characteristics during LBBAP.

Right Bundle Branch Block-Like Pattern During Uncomplicated Right Ventricular Pacing and the Effect of Pacing Site

Right bundle branch block (RBBB) configuration is an unexpected finding during right ventricular (RV) pacing that raises the suspicion of inadvertent left ventricular lead positioning. The aim of this study was to evaluate the prevalence of paced RBBB pattern in relation to RV lead location. This is a secondary analysis of a prospective, multicenter study, which randomized implantable cardioverter defibrillator recipients to an apical versus midseptal defibrillator lead positioning. A 12-lead electrocardiogram was recorded during intrinsic rhythm and RV pacing. Paced RBBB-like pattern was defined as positive (>0.05mV) net amplitude of QRS complex in leads V1 and/or V2. In total, 226 patients (65.6 ± 12.0years, 20.8% women, 53.1% apical site) were included in the study. The prevalence of paced RBBB pattern in the total population was 15.5%. A significantly lower percentage of patients in the midseptal group demonstrated RBBB-type configuration during RV pacing compared with the apical group (1.9% vs 27.5%, p <0.001). Baseline RBBB, prolonged QRS duration during intrinsic rhythm, and reduced ejection fraction were not associated with increased likelihood of paced RBBB. In the subgroup of patients with RBBB type during pacing, 91.4% of patients had a paced QRS axis from-30° to-90°, whereas 100% of patients displayed a negative QRS vector at lead V3. In conclusion, RBBB configuration is encountered in a considerable percentage of device recipients during uncomplicated RV pacing. Midseptal lead positioning is associated with significantly lower likelihood of paced RBBB pattern compared with apical location.

Right Bundle Branch Block–Like Pattern During Ventricular Pacing: A Surface Electrocardiographic Mapping Technique to Locate the Ventricular Lead

BackgroundIn patients with paced rhythm, a right bundle branch block (RBBB)-like pattern may suggest inadvertent left ventricular (LV) lead placement. However, in most cases, the lead is indeed in the right ventricle as intended. MethodsWe performed a retrospective analysis of postimplantation electrocardiograms (ECGs) for the period 2000-2013 to determine the prevalence of a RBBB-like pattern. A 12-lead ECG was recorded in the standard position and with displacement of leads V1-V2 to the fifth and sixth intercostal spaces (ICSs), assessing the ability of this manoeuvre to unmask a concealed LBBB-like pattern. Patients with true LV pacing, both endocardial and epicardial, were used as controls (n = 10). ResultsA total of 943 patients were analyzed. The prevalence of RBBB-like pattern was 8.1% (n = 77), and 26 patients were included in the study. Displacement of leads V1-V2 to the fifth ICS resulted in transition to a LBBB-like pattern with a QS wave in V1 in 14 of 26 patients (sensitivity, 53%; specificity, 100%), whereas displacement to the sixth ICS resulted in a QS pattern in all patients (sensitivity and specificity, 100%). In all patients in the control group, the ECG depicted a RBBB configuration with leads V1-V2 in the standard position, as well as at the fifth and sixth ICSs. ConclusionsIn patients with paced rhythm and a RBBB-like pattern on the 12-lead ECG, displacement of leads V1-V2 to the sixth ICS accurately identifies the presence of true right ventricular pacing.

An Unusual Cause of Intermittent Broad QRS Complexes

A 23-year-old asymptomatic male patient was admitted for invasive evaluation of pre-excitation on the surface ECG persisting during exercise testing. The electrophysiological study, performed under sedation with midazolam, revealed a midseptal accessory pathway (AP) with retrograde conduction and a 1:1 conduction during atrial pacing up to a cycle length of 240 ms. No tachycardia could be induced during pacing of the atrium and ventricle. We opted for ablation of the AP due to the malignant anterograde characteristics. Two seconds after the delivery of the first application of radiofrequency energy, the delta wave disappeared and normal atrioventricular conduction was restored. Energy application was continued for an additional 58 seconds. One day after the procedure, a control ECG revealed recurrence of the pre-excitation pattern. A second invasive evaluation was, therefore, scheduled 1 week after the initial electrophysiological study. Surprisingly, the surface ECG was normalized at that time, with AH and HV intervals within normal …

Right Bundle Branch Block on Alternate Beats during Acute Pulmonary Embolism

The electrocardiogram of a patient with acute pulmonary embolism showed right bundle branch block (RBBB) on alternate beats; following thrombolysis, the pattern evolved to persistent RBBB and eventually to normal conduction. Analysis of serial tracings suggested that the mechanism of RBBB alternans was tachycardia-dependent bidirectional bundle branch block, caused by prolongation of both anterograde and retrograde refractory periods (RPs) of the right bundle branch (RBB). The sinus impulse found the RBB refractory, and was conducted over the left bundle branch only, depolarizing the left ventricle and then attempting to penetrate retrogradely the RBB; at that time, however, the RBB was still refractory. When a QRS complex had a RBBB configuration, therefore, the RBB was not depolarized; the ensuing sinus impulse found the RBB fully responsive as a consequence of the long period intervening between two successive depolarizations, and resulted in normal intraventricular conduction. With right ventricular afterload decrease, the recovery of RBB anterograde and retrograde excitability was asynchronous, since the retrograde RP became normal earlier than the anterograde one. In accordance with the relatively short retrograde RP, the RBB was retrogradely invaded by the transseptal impulse coming from the left ventricle; this "shifted to the right" the anterograde RP of the RBB. The RBB, thus, was still refractory to the next sinus impulse, and RBBB again occurred; the RBB, thus, was once more depolarized retrogradely, and this led to perpetuation of RBBB. Finally, intraventricular conduction became normal owing to full normalization of RBB anterograde and retrograde refractoriness.

Purkinje‐Related Arrhythmias Part I: Monomorphic Ventricular Tachycardias

Purkinje-related monomorphic ventricular tachycardias (VTs) can be classified into four distinct groups: (1) verapamil-sensitive left fascicular VT, (2) Purkinje fiber-mediated VT post infarction, (3) bundle branch reentry (BBR) and interfascicular reentry VTs, and (4) focal Purkinje VT. There are three subtypes of fascicular VTs: (1) left posterior fascicular VT with a right bundle branch block (RBBB) configuration and superior axis; (2) left anterior fascicular VT with an RBBB configuration and right-axis deviation; and (3) upper septal fascicular VT with a narrow QRS configuration. The mechanism of the fascicular VT is macroreentry. While the antegrade limb of the circuit is a midseptal abnormal Purkinje fiber in the anterior and posterior fascicular VTs, the antegrade limb of the upper septal fascicular VT is both the anterior and posterior fascicles, and the retrograde limb is a midseptal abnormal Purkinje fiber. Purkinje fiber-mediated VT post infarction also exhibits verapamil sensitivity, and the surviving muscle bundles within the myocardium and Purkinje system are components of the reentry circuit. BBR-VT and interfascicular reentry VT are amenable to being cured by the creation of bundle or fascicular block. The mechanism of focal Purkinje VT is abnormal automaticity from the distal Purkinje system, and the ablation target is the earliest Purkinje activation during the VT. It is difficult to distinguish verapamil-sensitive fascicular VT from focal Purkinje VT by the 12-lead electrocardiogram; however, focal Purkinje VT is not responsive to verapamil . The recognition of the heterogeneity of these VTs and their unique characteristics should facilitate an appropriate diagnosis and therapy.

Diagnosis and Ablation of Fascicular Tachycardia

Verapamil-sensitive fascicular ventricular tachycardia (VT) is the most common form of idiopathic left VT. According to the QRS morphology and the successful ablation site, left fascicular VT can be classified into three subgroups: left posterior fascicular VT, whose QRS morphology shows right bundle branch block (RBBB) configuration and superior axis (common form); left anterior fascicular VT, whose QRS morphology shows RBBB configuration and right-axis deviation (uncommon form), and upper septal fascicular VT, whose QRS morphology shows narrow QRS configuration and normal or right-axis deviation (rare form). Posterior and anterior fascicular VT can be successfully ablated at the posterior or anterior mid-septum with a diastolic Purkinje potential during VT or at the VT exit site with a fused pre-systolic Purkinje potential. Upper septal fascicular VT can also be ablated at the site with diastolic Purkinje potential at the upper septum. Recognition of the heterogeneity of this VT and its unique characteristics should facilitate appropriate diagnosis and therapy.

Diagnosis and Ablation of Fascicular Tachycardia

Verapamil-sensitive fascicular ventricular tachycardia (VT) is the most common form of idiopathic left VT. According to the QRS morphology and the successful ablation site, left fascicular VT can be classified into three subgroups: left posterior fascicular VT, whose QRS morphology shows right bundle branch block (RBBB) configuration and superior axis (common form); left anterior fascicular VT, whose QRS morphology shows RBBB configuration and right-axis deviation (uncommon form), and upper septal fascicular VT, whose QRS morphology shows narrow QRS configuration and normal or right-axis deviation (rare form). Posterior and anterior fascicular VT can be successfully ablated at the posterior or anterior mid-septum with a diastolic Purkinje potential during VT or at the VT exit site with a fused pre-systolic Purkinje potential. Upper septal fascicular VT can also be ablated at the site with diastolic Purkinje potential at the upper septum. Recognition of the heterogeneity of this VT and its unique characteristics should facilitate appropriate diagnosis and therapy.

Characteristics of bundle branch reentrant ventricular tachycardia with a right bundle branch block configuration: feasibility of atrial pacing

We assessed the inducibility of bundle branch reentrant ventricular tachycardia (BBR-VT) with a right bundle branch block (RBBB) configuration in patients with BBR-VT. Eight consecutive patients (5 men, 45+/-18 years old) with inducible BBR-VT were included. We evaluated the clinical and electrophysiological characteristics in these patients to explore the inducible factors of BBR-VT with an RBBB configuration. Six of eight patients had inducible BBR-VT with an RBBB configuration, including four patients with a clinical VT with the same QRS morphology. All patients exhibited an LBBB or RBBB type intraventricular conduction disturbance during sinus rhythm. The mean HV interval at baseline was 79+/-18 ms. The reproducibility of the BBR-VT with an RBBB pattern was achieved by incremental atrial pacing during an isoproterenol infusion in 4/6 patients (67%) and by programmed ventricular stimulation in the other two. After a right bundle ablation, the BBR-VT was no longer inducible in any of the cases. Our results indicate that it is not rare to induce BBR-VT with an RBBB configuration. For the induction of an RBBB type BBR-VT, incremental atrial pacing may play a significant role in addition to ventricular pacing.

An Electrocardiographic Algorithm for Determining the Location of Pacemaker Electrode in Patients With Right Bundle Branch Block Configuration During Permanent Ventricular Pacing

The expected morphology of right ventricular pacing is a left bundle branch block (LBBB) pattern. However, right bundle branch block (RBBB) can also be seen during permanent right ventricular pacing. The aim of this study was to develop an electrocardiographic algorithm to differentiate this benign condition from septal and free wall perforation with subsequent left ventricular pacing. Three hundred consecutive patients who had permanent ventricular or dual-chamber pacemaker implantation between 1999 and 2000 were screened and 25 patients (8.3%) who exhibited RBBB configuration were included in the study. Echocardiograms and chest radiographs were evaluated in order to identify the pacing lead location in this group. The authors formed a study group with their own 25 patients and 22 cases of RBBB with permanent pacemaker from previous publications (total 47 patients). Frontal axis, QRS morphology in lead V(1), and the precordial transition point, which is defined as the precordial lead where R wave amplitude is equal to S wave amplitude, were examined. Placement of precordial leads V(1) and V(2) 1 interspace lower than the standard location (Klein maneuver) eliminated the RBBB pattern in 12 patients. RBBB pattern with "true right ventricular pacing" was detected in 24 of the 25 patients, and in 11 of the 22 patients reported in the literature (total 35 patients). Right ventricular pacing was correctly identified in 34 of 35 patients with use of criteria including left superior axis deviation, RS or qR morphology in lead V(1), and precordial transition at lead V(3) with a high sensitivity and specificity. A simple surface electrocardiogram can accurately predict the lead location in patients having RBBB morphology with right ventricular pacing.

Calcium channel antagonists and arrhythmias

Ca channel antagonists (CCA) including verapamil and diltiazem work as antiarrhythmic drugs. Because CCA suppresses conduction through atrio-ventricular (AV) node, it is effective on both AV reciprocating tachycardia (AVRT) and AV nodal reentrant tachycardia (AVNRT). It is also useful to reduce ventricular response during atrial fibrillation/flutter. Idiopathic left ventricular tachycardia (VT) with a right bundle-branch block configuration and superior axis is sensitive to verapamil, and thus called as verapamil-sensitive VT. A caution should be needed to prevent adverse effects based on cardio-depressive effects of CCA.

Verapamil-sensitive left anterior fascicular ventricular tachycardia: results of radiofrequency ablation in six patients.

Verapamil-sensitive left ventricular tachycardia (VT) with a right bundle branch block (RBBB) configuration and left-axis deviation has been demonstrated to arise from the left posterior fascicle, and can be cured by catheter ablation guided by Purkinje potentials. Verapamil-sensitive VT with an RBBB configuration and right-axis deviation is rare, and may originate in the left anterior fascicle. Six patients (five men and one woman, mean age 54+/-15 years) with a history of sustained VT with an RBBB configuration and right-axis deviation underwent electrophysiologic study and radiofrequency (RF) ablation. VT was slowed and terminated by intravenous administration of verapamil in all six patients. Left ventricular endocardial mapping during VT identified the earliest ventricular activation in the anterolateral wall of the left ventricle in all patients. RF current delivered to this site suppressed the VT in three patients (ablation at the VT exit). The fused Purkinje potential was recorded at that site, and preceded the QRS complex by 35, 30, and 20 msec, with pace mapping showing an optimal match between the paced rhythm and the clinical VT. In the remaining three patients, RF catheter ablation at the site of the earliest ventricular activation was unsuccessful. In these three patients, Purkinje potential was recorded in the diastolic phase during VT at the mid-anterior left ventricular septum. The Purkinje potential preceded the QRS during VT by 66, 56, and 63 msec, and catheter ablation at these sites was successful (ablation at the zone of slow conduction). During 19 to 46 months of follow-up (mean 32+/-9 months), one patient in the group of ablation at the VT exit had sustained VT with a left bundle branch block configuration and an inferior axis, and one patient in the group of ablation at the zone of slow conduction experienced typical idiopathic VT with an RBBB configuration and left-axis deviation. Verapamil-sensitive VT with an RBBB configuration and right-axis deviation originates close to the anterior fascicle. RF catheter ablation can be performed successfully from the VT exit site or the zone of slow conduction where the Purkinje potential was recorded in the diastolic phase.