Bundle Branch Reentry Research Articles

Bundle branch re-entry after transcatheter aortic valve replacement

Bundle branch re-entry after transcatheter aortic valve replacement

Radiofrequency catheter ablation of ventricular arrhythmias in patients with hypertrophic cardiomyopathy

BackgroundCompared to other non-ischemic substrates, there is limited data on the role and outcome of catheter ablation in HCM. The objective of this study is to assess the safety and efficacy of catheter ablation for the treatment of VT in patients with HCM. MethodsFourteen patients with HCM and drug refractory VT who underwent catheter ablation at a single center were included in this study. The data was evaluated retrospectively. Acute success, procedure-related complications, and long-term outcomes were documented during follow up. ResultsAmong the 14 patients (mean age 48.2 ± 8.2 years, 85.7% males, mean LVEF 42.6 ± 6.5%), 4 had an apical aneurysm. Eleven patients had evidence of scar-related VT and three patients had a bundle-branch re-entry VT. The most common sites for scar-related VT were the border-zones of the apical aneurysms, basal septum, and LV lateral wall. Patient either underwent an endocardial ablation or a combined endocardial and epicardial ablation. Acute success was achieved in all patients. In 6 patients VT was terminated during ablation. In two patients, non-clinical VTs were inducible at the end of the procedure. No major or minor complications were observed during and after the procedure in all patients. During long-term follow up, elimination of VTs reached 78%. ConclusionCatheter ablation of VT in patients with HCM is safe and successful in eliminating VT. Combining endocardial and epicardial ablation techniques can potentially lead to better outcomes in these patients. Bundle branch re-entry should be considered as a potential mechanism of VT in patients with HCM.

Catheter-induced right bundle branch block: Practical implications for the cardiac electrophysiologist.

The right bundle branch (RBB), due to its endocardial course, is susceptible to traumatic block caused by "bumping" during right-heart catheterization. In the era of cardiac electrophysiology, catheter-induced RBB block (CI-RBBB) has become a common phenomenon observed during electrophysiological studies and catheter ablation procedures. While typically transient, it may persist for the entire procedure time. Compared to pre-existing RBBB, the transient nature of CI-RBBB allows for comparative analysis relative to the baseline rhythm. Furthermore, unlike functional RBBB, it occurs at similar heart rates, making the comparison of conduction intervals more reliable. While CI-RBBB can provide valuable diagnostic information in various conditions, it is often overlooked by cardiac electrophysiologists. Though it is usually a benign and self-limiting conduction defect, it may occasionally lead to diagnostic difficulties, pitfalls, or undesired consequences. Avoidance of CI-RBBB is advised in the presence of baseline complete left bundle branch block and when approaching arrhythmic substrates linked to the right His-Purkinje-System, such as fasciculo-ventricular pathways, bundle branch reentry, and right-Purkinje focal ventricular arrhythmias. This article aims to provide a comprehensive practical review of the electrophysiological phenomena related to CI-RBBB and its impact on the intrinsic conduction system and various arrhythmic substrates.

Selective and non-selective right bundle pacing for the diagnosis of bundle branch reentry ventricular tachycardia.

Bundle branch reentry ventricular tachycardia (BBRVT) can be seen in patients with conduction disease. In this report, we describe the use of conduction system pacing for its diagnosis. BBRVT was induced in two patients with infra-nodal conduction disease. Bundle branch reentry ventricular tachycardia with a left bundle branch block morphology was observed in the first patient (type A), whereas the second patient had a right bundle branch block morphology (type C).The diagnosis of BBRVT was confirmed in both patients by ventriculo-atrial dissociation, and the interdependence of the conduction system and the ventricular tachycardia cycle length variations.Selective and non-selective RB pacing was observed in the two patients during apical right ventricular pacing for entrainment of BBRVT with evidence of manifest entrainment with non-selective RB capture in the first patient, and concealed entrainment by selective RB capture in the second patient. Other criteria for entrainment including a short post-pacing interval at the right bundle pacing site were noted. Right bundle pacing is feasible in patients with BBRVT and may be a helpful manoeuver for the diagnosis of BBRVT.

Ventricular arrhythmias in patients with prior aortic valve intervention: Characteristics, ablation and outcomes.

Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation in patients with aortic valve (AV) intervention (AVI) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of prosthetic valves. We sought to investigate the characteristics, safety, and outcomes of CA in patients with prior AVI and ventricular arrhythmias (VA). We identified consecutive patients with prior AVI (replacement or repair) who underwent CA for VT or PVC between 2013 and 2018. We investigated the mechanism of arrhythmia, ablation approach, perioperative complications, and outcomes. We included 34 patients (88% men, mean age 64 ± 10.4 years, left ventricular (LV) ejection fraction 35.2 ± 15.0%) with prior AVI who underwent CA (22 VT; 12 PVC). LV access was obtained through trans-septal approach in all patients except one patient who had percutaneous transapical access. One patient had combined retrograde aortic and trans-septal approach. Scar-related reentry was the dominant mechanism of induced VTs. Two patients had bundle branch reentry VTs. In the VT group, substrate mapping demonstrated heterogeneous scar that involved the peri-AV area in 95%. Despite that, the site of successful ablation included the periaortic region only in 6 (27%) patients. In the PVC group, signal abnormalities consistent with scar in the periaortic area were noted in 4 (33%) patients. In 8 (67%) patients, the successful site of ablation was unrelated to the periaortic area. No procedure-related complications occurred. The survival and recurrence-free survival rate at 1 year tended to be lower in VT group than in PVC group (p = .06 and p = .05, respectively) with a 1-year recurrence-free survival rate of 52.8% and 91.7%, respectively. No arrhythmia-related death was documented on long-term follow-up. CA of VAs can be performed safely and effectively in patients with prior AVI.

Recurring episodes of bundle branch reentry ventricular tachycardia due to aortitis preceded by SARS-CoV-2 infection: a case report

BackgroundSARS-CoV-2 may trigger both vasculitis and arrhythmias as part of a multisystem inflammatory syndrome described in children as well as in adults following COVID-19 infection with only minor respiratory symptoms. The syndrome denotes a severe dysfunction of one or more extra-pulmonary organ systems, with symptom onset approximately 2–5 weeks after the COVID-19 infection. In the present case, a seemingly intractable ventricular tachycardia preceded by SARS-CoV2 infection was only managed following the diagnosis and management of aortitis.Case presentationA 69-year-old woman was hospitalized due to syncope, following a mild COVID-19 infection. She presented with paroxysmal atrial fibrillation and intermittent ventricular tachycardia interpreted as a septum-triggered bundle branch reentry ventricular tachycardia, unaffected by amiodaron, lidocaine and adenosine. A CT-scan revealed inflammation of the aortic arch, extending into the aortic root. In the following days, the tachycardia progressed to ventricular storm with intermittent third-degree AV block. A temporary pacemaker was implanted, and radiofrequency ablation was performed to both sides of the ventricular septum after which the ventricular tachycardia was non-inducible. Following supplemental prednisolone treatment, cardiac symptoms and arrythmia subsided, but recurred after tapering. Long-term prednisolone treatment was therefore initiated with no relapse in the following 14 months.ConclusionWe present a rare case of aortitis complicated with life-threatening ventricular tachycardia presided by Covid-19 infection without major respiratory symptoms. Given a known normal AV conduction prior to the COVID-19 infection, it seems likely that the ensuing aortitis in turn affected the septal myocardium, enabling the reentry tachycardia. Generally, bundle branch reentry tachycardia is best treated with radiofrequency ablation, but if it is due to aortitis with myocardial affection, long-term anti-inflammatory treatment is mandatory to prevent relapse and assure arrhythmia control. Our case highlights importance to recognize the existence of the multisystem inflammatory syndrome in adults (MIS-A) following COVID-19 infection in patients with alarming cardiovascular symptoms. The case shows that the early use of an CT-scan was crucial for both proper diagnosis and treatment option.

Importance of the Activation Sequence of the His or Right Bundle for Diagnosis of Complex Tachycardia Circuits.

In this review, we emphasize the unique value of recording the activation sequence of the His bundle or right bundle branch (RB) for diagnoses of various supraventricular and fascicular tachycardias. A close analysis of the His to RB (H-RB) activation sequence can help differentiate various forms of supraventricular tachycardias, namely atrioventricular nodal reentry tachycardia from concealed nodofascicular tachycardia, a common clinical dilemma. Furthermore, bundle branch reentry tachycardia and fascicular tachycardias often are included in the differential diagnosis of supraventricular tachycardia with aberrancy, and the use of this technique can help the operator make the distinction between supraventricular tachycardias and these other forms of ventricular tachycardias using the His-Purkinje system. We show that this technique is enhanced by the use of multipolar catheters placed to span the proximal His to RB position to record the activation sequence between proximal His potential to the distal RB potential. This allows the operator to fully analyze the activation sequence in sinus rhythm as compared to that during tachycardia and may help target ablation of these arrhythmias. We argue that 3 patterns of H-RB activation are commonly identified-the anterograde H-RB pattern, the retrograde H-RB (right bundle to His bundle) pattern, and the chevron H-RB pattern (simultaneous proximal His and proximal RB activation)-and specific arrhythmias tend to be associated with specific H-RB activation sequences. We show that being able to record and categorize this H-RB relationship can be instrumental to the operator, along with standard pacing maneuvers, to make an arrhythmia diagnosis in complex tachycardia circuits. We highlight the importance of H-RB activation patterns in these complex tachycardias by means of case illustrations from our groups as well as from prior reports.

B-PO05-117 VENTRICULAR TACHYCARDIA INVOLVING THE CONDUCTION SYSTEM IN STRUCTURAL HEART DISEASE: PREVALENCE, MECHANISMS, AND OUTCOMES

While conduction system ventricular tachycardia (VT) in idiopathic substrates has been well characterized. The spectrum of monomorphic VT involving the Purkinje system in structural heart disease (SHD) is incompletely described. Analyze the prevalence, mechanisms, and outcomes of conduction system VTs in structurally abnormal hearts at a single institution. Retrospectively analyzed 340 consecutive scar-related monomorphic VT ablation procedures performed at the University of Chicago from March 2016 to January 2021. Patient characteristics, procedural outcomes, recurrence of VT and clinical course were reviewed. Fourteen patients accounted for 15 procedures (4.4% of total ablations) targeting the conduction system. The mean age was 55±12 years, 23% female, mean ejection fraction 29±13%, 43% ischemic heart disease, and 57% non-ischemic heart disease. In this cohort 64% had previous ablations for VT prior to admission with a mean of 1±0.9 procedures per patient; 93% of the patients were on antiarrhythmic medications prior to the procedure. The spectrum of arrhythmia mechanisms included 60% bundle branch reentry, 13% fascicular reentry, 13% scar VT with fascicular exit, and 13% interfascicular reentry. Two patients expired during their hospitalization. No patient had a new device requirement post ablation. Eighty-six percent of the patients demonstrated freedom from VT post procedure. A diverse spectrum of Purkinje involvement in reentrant VT was observed in patients with structural heart disease. Twelve out of 14 patients were free of VT post ablation.

Alternating wide complex tachycardia after surgical aortic valve replacement

A 51-year-old male developed recurrent episodes of palpitations and pre-syncope after surgical aortic valve replacement. Electrocardiograms after surgery revealed a wide complex tachycardia with alternating left bundle branch and right bundle branch block morphologies. An electrophysiology study (EPS) demonstrated typical bundle branch reentry ventricular tachycardia (BBRVT) treated successfully with right bundle ablation. We demonstrate the key diagnostic features of BBRVT on EPS, describe the circuit of BBRVT with explanation of the HV pseudointerval, and highlight the association of BBRVT and valve replacement.

Complex Re-Entrant Arrhythmias Involving the His-Purkinje System: A Structured Approach to Diagnosis and Management.

This study sought to characterize the presentations, electrophysiological features and diagnostic maneuvers for a series of unique arrhythmias involving the HPS. By virtue of its unique anatomy and ion channel composition, the His-Purkinje system (HPS) is prone to a variety of arrhythmic perturbations. The authors present a collaborative multicenter case series of 6 patients with HPS-related arrhythmias. Allpatients underwent electrophysiological studies using standard multipolar catheters. In 3 patients, both typical and reverse bundle branch re-entry were seen, with 1 patient demonstrating "figure of 8" re-entry likely involving the septal fascicle. One patient presented with systolic dysfunction associated with a high premature ventricular complex burden, with the mechanism being bundle-to-bundle re-entrant beats masquerading as dual response to a single sinus impulse. Two patients were diagnosed with interfascicular re-entry. Diagnosis was aided by careful assessment of HV interval in sinus rhythm and ventricular tachycardia, multipolar catheters to assess the activation sequence of the His-right bundle branch, and fascicles and entrainment of different components of the HPS. Cure of the arrhythmia was achieved by ablation of the right bundle branch block in 3 patients, the left septal fascicle in 2patients, and the left posterior fascicle in 1 patient. Proper diagnosis of re-entrant arrhythmias involving the HPS may prove challenging. We emphasize a structured approach for diagnosis and effective therapy.

Ablation of Ventricular Tachycardia Storm in a Patient with Biventricular Mechanical Support Devices - A Case Report

Background Ventricular tachycardia (VT) has been described in patients who have undergone implantation of ventricular assist devices (VAD). Mechanisms for VT in these patients include scar-mediated reentry, bundle branch reentry, and mechanically-induced arrhythmia related to scar caused by VAD inlet cannula placement or suction events. While the hemodynamic support offered by VAD's can mitigate the harmful effects of ventricular tachyarrhythmias, morbidity can arise from outcomes including RV failure. VT ablation has been utilized with some success in these patients though data in this area is scarce, especially in those with biventricular support devices. Case Report We present a case of a 47 year-old man with a history of hypertension, tobacco and cocaine abuse presenting with STEMI. Despite emergent catheterization with PCI to proximal LAD lesion, he developed cardiogenic shock requiring intra-aortic balloon pump placement. He subsequently suffered V Fib arrest necessitating upgrade to VA-ECMO. Due to persistent biventricular failure with inability to wean support, he was transitioned to durable left ventricular support (Heartmate 3, Abbott) and temporary right ventricular support (Protek Duo, TandemLife). Despite durable support, he remained in VT refractory to antiarrhythmic agents (Amiodarone, Lidocaine, Procainamide), multiple cardioversions, and stellate ganglion block. Given incessant VT leading to RV failure and compromising RVAD removal, the decision was ultimately made to proceed with VT ablation. The patient underwent extensive substrate-based ablation and ablation of the right bundle and left posterior fascicle for bundle branch reentry and interfascicular VT complicated by transient AV block requiring TVP insertion. Other complicating factors involved in this procedure included gaining access and manipulating ablation catheters given presence of prior devices including the LVAD cannula. At the end of the procedure the patient had no further inducible VT. He was successfully weaned off of RVAD support after the ablation. His hospital course was complicated by recurrent slower VT which was successfully managed with medical therapy. Conclusions Our case highlights several complicating factors in managing ventricular tachyarrhythmias in patients with mechanical circulatory support devices. These include limitations to medical management due to side effect profiles or refractoriness, coordination of multiple disciplines (advanced heart failure, EP, VAD team, anesthesia), as well as barriers to successful ablation including technical difficulty given the presence of other devices, the desire to avoid invasive procedures in patients susceptible to or suffering from systemic infection, and high recurrence rates. In this specific case VT ablation was successful in facilitating the goal of weaning the patient off of RVAD support.

When The “Genes” No Longer Fit: An Unusual Presentation of LMNA-related Cardiomyopathy

Introduction The diagnosis of dilated cardiomyopathy from genetic mutation of Lamin A/C (LMNA) is quite challenging in absence of known family disease or signs of skeletal myopathy. We present a case of high-grade AV block and septal ventricular tachycardia (VT) requiring orthotopic heart transplantation with post-transplant genetic testing showing LMNA-related dilated cardiomyopathy. Case A 58-year-old man with history of orthotopic liver transplant (OLT) for Hepatitis C cirrhosis and no familial cardiac history initially presented with symptomatic, sustained left bundle left superior axis ventricular tachycardia at 230 bpm. Baseline ECG after DCCV demonstrated a LBBB with periods of 2:1 AV block. Patient underwent an ischemic evaluation which was unremarkable. Cardiac MRI was negative for infiltrative disease but did show midmyocardial late gadolinium enhancement at the inferoseptal and apical right ventricle. He underwent secondary prevention CRT-D implantation. He had recurrent VT requiring radiofrequency ablation for inducible bundle-branch reentry VT. One year later, he presented with recurrent VT and underwent attempted radiofrequency ablation of numerous septal VT morphologies resulting in shock-refractory sustained VT complicated by cardiogenic shock requiring VA-ECMO and ultimately orthotopic heart transplantation. Pathology of the explanted heart showed scarring and fatty infiltration of the RV septum and free wall suggestive of a variant of arrhythmogenic right ventricular cardiomyopathy (ARVC). However, despite suspicion for ARVC on pathology, genetic testing showed a genetic mutation in Lamin A/C Gene, suggestive of laminopathy. Conclusion Our case shows that LMNA-related dilated cardiomyopathy can present with phenotypic appearance similar to patients with pathologic suspicion of ARVC. Although LMNA-related dilated cardiomyopathy contributes to 6-8% of familial related cardiomyopathy, it is often difficult to diagnose due to its inheritance and penetrance. Patients presenting with unclear etiology of dilated cardiomyopathy and malignant ventricular arrhythmias should prompt a suspicion for LMNA-related cardiomyopathy.

Catheter ablation of ventricular tachycardia in the pediatric patients: A single-center experience.

Ventricular tachycardia (VT) with or without structural heart disease is uncommon but well-recognized clinically in children. With this retrospective study, we collected the data from the in-hospital pediatric patients of VT with catheter ablation therapy. The purpose of this study is to assess the acute results and the long-term outcome of catheter ablation in pediatric patients of VT in our single pediatric center. This study included 53 consecutive children (male/female=33/20, mean age=8.2±3.4 years, mean bodyweight=32.6±13.7kg). All patients underwent electrophysiological study with an attempt of catheter ablation for clinical monomorphic VT. Acute and long-term success rate of catheter ablation for the treatment of VT were compared between right and left VT as well as fascicular VT (FVT) and nonfascicular VT. There were 53 idiopathic VT forms found in the children, including FVT (n=32), outflow tract VT (n=15), papillary muscle VT (n=5), and bundle branch reentry VT (n=1). Acute success of catheter ablations for VT was achieved in 57 of all the 59 ablation procedures (97%) with VT recurrence occurred in six of 53 patients (11%). During a mean follow-up period of 29.2±21.7 months (range 1-76 months) after hospital discharge, ablations in nonfascicular VT were as successful as FVT. There was no significant difference in the success rate between the right and left VT. Catheter ablation is an effective treatment for idiopathic VT in children. The acute and long-term success rates of catheter ablation for idiopathic VT in pediatric patients with normal heart structure are satisfying.

Catheter ablation for monomorphic ventricular tachycardia in Brugada syndrome patients: detailed characteristics and long-term follow-up.

Brugada syndrome (BrS) is a risk of sudden cardiac death due to polymorphic ventricular tachycardia and ventricular fibrillation with unusual monomorphic ventricular tachycardia (MVT). Detailed characteristics of MVT and long-term outcome of catheter ablation are still unknown. This study is aimed to identify the detailed characteristics and long-term follow-up of catheter ablation in BrS patients. We evaluated 188 patients who were diagnosed with BrS from March 1999 to March 2018. Of those, patients who developed MVT and underwent catheter ablation were included. We identified eight MVTs in seven BrS patients. Three of them already had implantable cardioverter-defibrillator, and MVTs were terminated by cardioversion or anti-tachycardia pacing. Four patients presented with MVT originating from the right ventricular outflow tract, one patient had MVT arising from the LV septum, one patient had MVT arising from the tricuspid annulus, and one patient had bundle branch reentry ventricular tachycardia. All MVTs were successfully treated by catheter ablation in the acute phase, and seven of eight (87.5%) were free from ventricular tachyarrhythmia during the long-term follow-up (median, 7.2years). All MVT cases were successfully treated by catheter ablation. We observed high ventricular arrhythmia free rate following catheter ablation during the long-term follow-up period. BrS patients who developed MVT should consider catheter ablation.

Electrophysiologic Substrate, Safety, Procedural Approaches, and Outcomes of Catheter Ablation for Ventricular Tachycardia in Patients After Aortic Valve Replacement

This study sought to investigate the substrate, procedural strategies, safety, and outcomes of catheter ablation (CA) for ventricular tachycardia (VT) in patients with aortic valve replacement (AVR). VT ablation in patients with AVR is challenging, particularly when mapping and ablation in the periaortic region are necessary. We identified consecutive patients with mechanical, bioprosthetic, and transcatheter AVR who underwent CA for VT refractory to antiarrhythmic drugs and analyzed VT substrate, approach to LV access, complications, and long-term outcomes. Overall, 29 patients (87% men, mean age 67.9 ± 9.8 years, left ventricular ejection fraction 39 ± 10%) with prior AVR (13 mechanical, 15 bioprosthetic, 1 transcatheter AVR) underwent 40 ablations from 2004 to 2016. Left-sided mapping/CA was performed in 27 patients (36 procedures). Access was retrograde aortic in 11 procedures (all bioprosthetic), transseptal in 24 (13 mechanical; 10 bioprosthetic; 1 transcatheter AVR), or transventricular septal in 1. Periaortic bipolar or unipolar scar was detected in all 24 patients in whom detailed periaortic mapping was performed. Clinical VT circuit(s) involved the periaortic region in 10 patients (34%), 2 (7%) had bundle branch re-entry VT, and 17 (59%) had substrate unrelated to AVR. There were 2 major complications (both related to vascular access). Only 2 patients (9.1%) had VT recurrence. Over median follow-up of 12.8 months, 11 patients died (none as a result of recurrent VT). Whereas most patients undergoing CA for VT after AVR had VT from substrate unrelated to AVR, periaortic scar is universally present and bundle branch re-entry can be the VT mechanism. CA can be safely performed with excellent long-term VT elimination.

Electrophysiological Characteristics of Bundle Branch Reentry Ventricular Tachycardia in Patients Without Structural Heart Disease

The distinct electrophysiological features of bundle branch reentry ventricular tachycardia (VT) in patients without structural heart disease have not been systemically characterized. Nine patients (mean age, 29.6 years) with normal left ventricular function were enrolled. Bundle branch reentry VT with right and left bundle branch block (BBB) patterns was induced in 1 and 9 patients, respectively. The right bundle was attempted to record by a 6F decapolar or quadripolar catheter. Electroanatomic mapping of the left ventricle was performed in 6 patients. In all left BBB pattern VT, the mean VT cycle length was 329.3±89.1 ms, and the median HV interval during tachycardia was longer than that of baseline (78 [73-100] versus 71 [64.5-88] ms; P=0.11). The H-RB interval during VT was slightly shorter (P=0.14); however, the median RB-V interval was markedly longer than that during sinus rhythm (50 [29.5-83] versus 30 [8-51] ms; P=0.043]. In 6 patients with 3-dimensional mapping of the left ventricle, a slow anterograde or retrograde conduction over left HIS-Purkinje system with normal myocardial voltage was identified. In addition, Purkinje-related VTs (1.0±1.3 types) were also induced in 5 patients. Ablation was applied in distal left BB in patients with baseline left BBB and in one narrow QRS patient with sustained Purkinje-related VT, whereas right BB was targeted in other patients. During a mean follow-up of 31.4 months, frequent premature ventricular contractions occurred in one patient, and new VT developed in the other patient. Bundle branch reentry VT can occur in young patients with extensive conduction disturbances within HIS-Purkinje system. Ablation targeting at the distal left BB which bifurcates into left posterior and anterior fascicle can preserve the residual atrioventricular conduction, but intensive follow-up is needed.

Characterization of Ventricular Tachycardia After Left Ventricular Assist Device Implantation as DestinationTherapy: A Single-Center Ablation Experience.

This study sought to report mechanisms of ventricular tachycardia (VT) and outcomes of VT ablationinpatients with a left ventricular assist device (LVAD) as destination therapy. Continuous flow LVAD implantation plays a growing role in the management of end-stage heart failure, and VT is common. There are limited reports of VT ablation in patients with a destination LVAD. Patients with a continuous-flow LVAD referred for VT ablation from 2010 to 2016 were analyzed retrospectively. Baseline patient characteristics, procedural data, and clinical follow-up were evaluated. Arrhythmia-free survival was assessed. Twenty-one patients (90% male, 62 ± 10 years) underwent catheter ablation of VT at a median of 191 days (interquartile range: 55 to 403 days) after LVAD implantation (15 HeartMate II, 6 HeartWare HVAD). Five patients (24%) had termination (n= 4) or slowing (n= 1) of VT with ablation near the apical inflow cannula, and 3 (14%) had bundle-branch re-entry. Freedom from recurrent VT among surviving patients was 64% at 1 year, with overall survival 67% at 1 year for patients without arrhythmia recurrence and 29% for patients with recurrence (p= 0.049). One patient had suspected pump thrombosis within 30 days of the ablation procedure, with no other major acute complications. In this relatively large, single-center experience of VT ablation in destination LVAD, freedom from recurrent VT and implantable cardioverter-defibrillator shocks was associated with improved 1-year survival. Bundlebranch re-entry was more prevalent than anticipated, and cannula-adjacent VT was less common. This challenging population remains at risk for late pump thrombosis and mortality.

Diagnostic Perturbations.

Diagnostic Perturbations.

Bundle branch reentry VT : Diagnosis, mapping, and ablation

Macroreentry in the His-Purkinje system can result in sustained ventricular tachycardia (VT) termed bundle branch reentry VT. Bundle branch reentry is usually associated with His-Purkinje disease and depressed left ventricular function. In the case of typical bundle branch reentry, the right bundle is activated in the anterograde direction and ventricular depolarization begins at the distal end of the right bundle on the ventricular septum generating atypical left bundle branch block QRS morphology. However, atypical surface ECGs can also be found in patients with severe left ventricular dysfunction and involvement of the right ventricle complicating the diagnosis of bundle branch reentry VT. It is important to diagnose bundle branch reentry VT because patients with bundle branch reentry VT may suffer from ahigh rate of serial implantable cardioverter defibrillator (ICD) interventions based on VT recurrences due to immediate reinitiation of the arrhythmia. Ablation of the right bundle branch easily cures bundle branch reentry VT and can prevent frequent ICD interventions. After ablation of bundle branch reentry VT, mortality remains high due to the severe left ventricular dysfunction in many patients, and the patients are candidates for cardiac resynchronization therapy (CRT-D).

Atypical Surface ECG Complicating the Diagnosis of Bundle Branch Reentry Tachycardia

Typical left bundle branch block (LBBB) during ventricular tachycardia (VT) is a diagnostic criterion of bundle branch reentry tachycardia (BBRT) with activation of the right bundle in the anterograde direction. Eleven patients (seven male, 60 ± 12 years) with nonischemic cardiomyopathy (left ventricular ejection fraction 37 ± 16%) presenting with BBRT were successfully treated by ablation of the right bundle. Among them, five patients had atypical surface electrocardiograms (ECGs) differing from a typical LBBB during the VT. Three patients with severe enlargement and dysfunction of the left ventricle had broadened irregular QRS complexes with rR or RS configuration in lead V6 during the BBRT. Two patients with enlargement and/or hypokinesia of the right ventricle had entirely or almost entirely negative complexes (QS) in the chest leads (V1-V6) during the VT. Activation mapping in these two patients revealed that the exit site of the BBRT was in the anterior right ventricle generating a negative concordance in the precordial leads. Atypical surface ECGs with broadened irregular QRS complexes or negative concordance in the precordial leads can complicate the correct diagnosis of BBRT in patients with severe left ventricular dysfunction and involvement of the right ventricle.