Bundle Branch Reentry Ventricular Tachycardia with Two Distinct Left Bundle Branch Block Morphologies

Bundle Branch Reentry VT with Two Morphologies. Introduction: Bundle branch reentry ventricular tachycardia (VT) is usually amenable to treatment with radiofrequency ablation. Different QRS morphologies during VT are possible when anterograde ventricular activation is over the left bundle branch. Manifestations of tbis reentrant tachycardia with more than one QRS morphology with anterograde activation via the right bundle have not been reported and would be unusual due to the more discrete anatomy of the right bundle branch. Methods and Results: An electropbysiologic study was conducted in a patient with dilated ventricle and diminished ventricular function with VT, Typical characteristics of bundle branch reentry were noted when VT was induced. The study was notable for the presence of a right bundle recording only during macroreentrant beats or VT and the distal location of the recording. Radiofrequency ablation was performed. Postablation stimulation again induced VT, proven to be of the same bundle branch reentry mechanism but of a different QRS morphology. A second ablation was required for complete ablation of this patient's bundle branch reentry VT. Conclusion: In bundle branch reentry utilizing the left bundle as the retrograde limb and the right bundle branch as the anterograde limb of the circuit, VT of more than one distinct morphology can be seen. Careful evaluation to assess for the persistence of VT of the same mechanism is necessary to ensure complete ablation of the reentrant circuit. Preexisting right bundle disease and a dilated heart with more dispersed distal right bundle branches may predispose to such a phenomenon.     

Bundle Branch Reentry Ventricular Tachycardia:

Bundle Branch Reentry VT. We describe a patient with bundle branch reentry ventricular tachycardia with 1:1 VA conduction in whom resetting was performed while obtaining simultaneous recordings from the right ventricular apex (V) and His-bundle electrogram. Both the tachycardia return cycle and the V-His interval demonstrated an increasing reset response, while the His-V interval demonstrated a flat reset response. These reset responses are consistent with a partially excitable gap localizing to the V-His portion of the bundle branch reentry circuit.     

Adenosine-Sensitive Bundle Branch Reentry

Adenosine-Sensitive Bundle Branch Reentry. Introduction: Bundle branch reentry is an uncommon mechanism for ventricular tachycardia. More infrequently, both fascicles of the left bundle may provide the substrate for such macroreentrant bundle branch circuits, so-called interfascicular reentry. The effect of adenosine on bundle branch reentrant mechanisms of tachycardia is unknown.
Methods and Results : A 59-year-old man with no apparent structural heart disease and history of frequent symptomatic wide complex tachycardias was referred to our center for further electrophysiologic evaluation. During electrophysiologic study, a similar tachycardia was reproducibly initiated only during isoproterenol infusion, which had the characteristics of bundle branch reentry, possibly using a left interfascicular mechanism. Intravenous adenosine reproducibly terminated the tachycardia. Application of radiofrequency energy to the breakout site from the left posterior fascicle prevented subsequent tachycardia induction and rendered the patient free of spontaneous tachycardia during long-term follow-up.
Conclusions : Patients with ventricular tachycardia involving a bundle branch reentrant circuit may be sensitive to adenosine. These results suggest that adenosine may not only inhibit catecholamine-mediated triggered activity but also some catecholamine-mediated reentrant ventricular arrhythmias.     

Facilitation of Sustained Bundle Branch Reentry by Atrial Fibrillation

Sustained Bundle Branch Reentry. An electrophysiologic evaluation was performed in a patient with an idiopathic dilated cardiomyopathy and syncope. Ventricular tachycardia was not inducible despite the use of a variety of pacing maneuvers during sinus rhythm. Only after the electrical induction of atrial fibrillation did sustained bundle branch reentrant tachycardia (with both right and left bundle branch block QRS configurations) spontaneously occur and become reproducibly induced during right ventricular pacing. Ablation of the right bundle branch eliminated reproducibility of the tachycardia.     

Catheter Ablation of Coexistent Bundle Branch and Interfasdcular Reentrant Ventricular Tachycardias

Bundle Branch and Interfascicular Reentry. Introduction : Bundle branch reentry and interfascicular reentry are potential mechanisms of ventricular tachycardia in the setting of a dilated cardiomyopathy. We report a patient with myotonic dystrophy who presented with near syncope, in whom both of these mechanisms were present, leading to two different wide complex tachycardias.
Methods and Results : Electrophysiologic study demonstrated Infra-Hisian conduction system disease and inducible bundle branch reentrant ventricular tachycardia. Catheter ablation of the right bundle eliminated bundle branch reentry. However, following this, the patient had inducible interfascicular reentry, which subsequently occurred spontaneously while still hospitalized. Catheter ablation of the left posterior fascicle successfully eliminated this second tachycardia, and the patient has had no further arrhythmias.
Conclusions : This report is of an unusual patient with coexistent bundle branch reentry and interfascicular reentry producing two different forms of sustained ventricular tachycardia. This is the first report of catheter ablation of the left posterior fascicle for elimination of conduction system reentry.     

Becker Muscular Dystrophy with Bundle Branch Reentry Ventricular Tachycardia

Muscular Dystrophy with Ventricular Tachycardia. This report describes a case of Becker muscular dystrophy presenting with recurrent symptomatic wide complex tachycardia. Electrophysiologic testing demonstrated the mechanism to be bundle branch reentry ventricular tachycardia. It is important to consider this potential mechanism in patients with ventricular arrhythmias who have this particular clinical entity, since radiofrequency catheter ablation can represent a curative treatment.     

AV Nodal-His-Purkinje Reentry: A Novel Form of Tachycardia

AV Nodal-His-Purkinje Reentry. Introduction: Bundle branch reentry (BBR) typically occurs in patients with dilated cardiomyopathy and infra-Hisian conduction system disease. The macroreentrant circuit of BBR is confined to the His-Purkinje system (HPS) and ventricular myocardium. As such, the atrioventricular (AV) node plays no role in the tachycardia circuit. Methods and Results: In the present study, we identified a novel form of wide complex tachycardia in a patient with coronary disease and severe aortic regurgitation. The tachycardia morphology was right bundle branch block with a left superior axis. Ventriculoatrial block was present during tachycardia. An unusual feature of this rhythm was two sequential His-bundle deflections (H and H′) for each ventricular beat of tachycardia. The H′V interval was identical to the HV interval during supraventricular rhythm. Changes in the ventricular cycle length (VV) preceded changes in the HH interval, consistent with retrograde activation of the first His-bundle deflection. Changes in the H ‘H’interval preceded changes in the VV interval, consistent with anterograde activation of the second His-bundle deflection. Tachycardia could be terminated with ventricular extrastimuli that did not capture the proximal HPS as well as with ventricular extrastimuli that advanced the His deflection, consistent with block in the HPS and in the AV node, respectively. Reproducible termination of the tachycardia following the first His deflection was demonstrated with adenosine, consistent with an upper pivot in the AV node. Conclusions: We have identified a new form of reentrant tachycardia in which the AV node, HPS, and ventricular myocardium each obligatorily participates in the tachycardia circuit, with the left posterior fascicle and right bundle functioning as the anterograde and retrograde limbs, respectively. Unlike BBR, however, the His bundle is activated twice as the wavefront pivots in the AV node. This model requires longitudinal dissociation at the levels of the AV node and His bundle.     

Atypical Atrioventricular Nodal Reentry Tachycardia with Atrioventricular Block Mimicking Atrial Tachycardia:

AVNRT Mimicking Atrial Tachycardia, Introduction : Fast-intermediate form AV nodal reentry tachycardia (AVNRT) sometimes may mimic atrial tachycardia or atrial flutter and render the diagnosis difficult when the tachycardia rate is fast and AV block occurs during tachycardia.
Methods and Results : A 45-year-old woman with paroxysmal supraventricular tachycardia was referred to this institution. Initially, the tachycardia was thought to be an atrial tachycardia because of: (1) a short cycle length of the tachycardia with 2:1 and Wenckebach AV block; (2) a difference in the atrial activation sequence during tachycardia and during ventricular pacing; and (3) failure of burst ventricular pacing to affect the atrial rate and the atrial activation sequence during tachycardia. An accurate diagnosis of fast-intermediate form AVNRT was subsequently made based on the finding that the tachycardia was induced following delivery of a third ventricular extrastimulus, which showed a sequence of V-A-H and a change on atrial activation sequence of the induced beat. Successful radiofrequency ablation was achieved only after accurate diagnosis of the tachycardia was made.
Conclusion : Fast-intermediate form AVNRT sometimes may masquerade as atrial tachycardia. Accurate diagnosis is mandatory for successful ablation therapy.     

Radiofrequency Modification for Inducible and Suspected Pediatric Atrioventricular Nodal Reentry Tachycardia

Introduction: AV Node Reentry Tachycardia (AVNRT) is the second most common supraventricular tachycardia (SVT) undergoing pediatric radiofrequency ablation behind accessory pathway reentry tachycardias. AVNRT can be difficult to induce during electrophysiology study (EPS) and dual atrioventricular nodal (AVN) pathways physiology may not be demonstrated in young patients.Purpose: This report is the largest single center long term pediatric experience of radiofrequency modification of slow AVN input fibers for inducible or suspected (non-inducible) AVNRT.Results: One hundred thirty-two patients underwent slow input AVN modification from 1993 to 2002. The mean patient age was 13.7 years (4–20 yrs) with 62M/70F. Outpatient tachycardia was documented by ambulatory monitoring in all patients. AVNRT was induced in 98/132 patients during EPS (group A) with mean SVT cycle length of 324 msec (230–570 msec). Initial AVN modification (group A) was successful in 97/98 patients (99%). During 34/132 EPS, AVNRT was non-inducible; dual AVN physiology was present in 19/34 (group B), and 15/34 did not show evidence for dual AVN physiology (group C). These 34 patients underwent empiric AVN modification following discussion with patients’ families. Freedom of recurrence from SVT at 1 year was 96% for group A (94/98), 89% (17/19) for group B and 93% (14/15) for group C. 1 major and 6 minor complications occurred.Conclusions: AVN modification for AVNRT can be performed safely and effectively in pediatric patients with good long-term results. Empiric slow pathway AVN modification for non-inducible SVT results in a high rate of freedom from recurrence of tachycardia.     

Cure of Interfascicular Reentrant Ventricular Tachycardia by Ablation of the Anterior Fascicle of the Left Bundle Branch

Ablation of Interfascicular Reentrant Tachycardia. Introduction: Fascicular reentrant ventricular tachycardia (VT) using the anterior fascicle of the left bundle anterogradely is rare and may produce identical QRS morphology during sinus rhythm and VT. Catheter ablation of this type of VT has not been described in detail.
Methods and Results: In a postinfarct patient with dilated left ventricle and recurrent VT (showing a QRS configuration of right bundle branch, left posterior fascicular block), endocardial recordings from the His-Purkinje system showed that VT was due to interfascicular reentry. Induction of VT occurred after progressive retrograde conduction delay on increasing the prematurity of the extrastimulus. Anterograde conduction occurred exclusively over the left anterior fascicle, which caused identical QRS morphology during sinus rhythm and VT. During VT, the left posterior fascicle was used retrogradely. The usual target for bundle branch reentry ablation, the right bundle, did not participate in the reentrant circuit. While performing left ventricular endocardial mapping, VT was interrupted when positioning the catheter on the left anterior fascicle, and "reversed" nonsustained bundle branch reentry occurred with anterograde conduction over the posterior fascicle and retrograde conduction over the anterior fascicle. Ablation of conduction in the anterior fascicle led to cure of the VT.
Conclusion: Interfascicular reentrant VT with right bundle branch block, right-axis QRS configuration can be cured by catheter ablation of anterior fascicle conduction.     

Catheter Ablation of the Left Bundle Branch for the Treatment of Sustained Bundle Branch Reentrant Ventricular Tachycardia

Sustained Bundle Branch Reentrant VT. Radiofrequency catheter ablation of the left bundle branch (LBB) was attempted in a patient with sustained bundle branch reentry. During sinus rhythm, the QRS had a complete LBB block pattern, and the LBB was activated retrogradely (transseptal). Ablation of the LBB eliminated inducibility of the tachycardia, while the QRS complex and the duration of the HV interval (70 msec) remained unchanged. Successful ablation of the LBB eliminated bundle branch reentry and yet maintained the anterograde conduction properties of the His-Purkinje system, obviating implantation of a permanent pacemaker.     

Bundle branch reentry ventricular tachycardia in arrhythmogenic right ventricular dysplasia

A 42-year-old male had history of recurrent palpitation and was documented to have wide QRS tachycardia. Magnetic resonance imaging angiogram showed evidence of arrhythmogenic right ventricular dysplasia and severe right ventricular dysfunction. Electrophysiology study showed evidence of bundle branch reentry ventricular tachycardia. It was successfully treated by radiofrequency ablation of right bundle branch. This is probably the first case of bundle branch reentry as a mechanism for ventricular tachycardia in a case of arrhythmogenic right ventricular dysplasia.     

Bundle Branch Reentrant Ventricular Tachycardia in a Patient with the Brugada Electrocardiographic Pattern

A 55‐year‐old, previously healthy man presented with an episode of wide QRS tachycardia that had left bundle branch morphology and left superior axis. His electrocardiogram in sinus rhythm showed characteristic Brugada pattern with coved type ST‐segment (J‐point) elevation in leads V₁–V₂, mild QRS widening of 110 ms, and left axis deviation. The mechanism of the tachycardia was shown to be bundle branch reentry. Baseline H‐V interval of 68 ms additionally lengthened to 119 ms after intravenous procainamide administration indicating significant conduction system disease. The tachycardia was no longer inducible after successful ablation of the right bundle branch.     

Tachycardia with wide ventricular complexes and alternating QRS complexes and RR intervals

A patient with sustained monomorphic ventricular tachycardia developed a second tachycardia of incessant character with alternating RR-interval and alternating QRS-complexes after treatment with amiodarone. A retrograde His bundle deflection was recorded during the latter arrhythmia, that was induced as well with atrial as with ventricular stimulation. The "alternating" tachycardia could be explained by alternating bundle branch reentry and alternating conduction in the myocardium. This view is supported by the finding of an alternating mid-diastolic potential. This case report introduces a new electrocardiographic entity in the spectrum of wide QRS-tachycardias.     

High-resolution mapping of tachycardia originating from the superior vena cava: evidence of electrical heterogeneity,slow conduction,and possible circus movement reentry

Superior Vena Cava Reentry. High-resolution mapping of a tachycardia originating from the superior vena cava (SVC) in a patient with atrial fibrillation is described. Unidirectional circuitous repetitive activation encompassing the full tachycardia cycle length was documented around a line of block within the myocardial sleeve of the SVC. Intermittent conduction to the right atrium resulted in an irregular atrial tachycardia. Evidence of electrical heterogeneity and slow conduction persisted in sinus rhythm and was exaggerated by premature stimulation but did not reproduce the activation pattern during tachycardia. All the available evidence is best compatible with circus movement reentry within the SVC, with marked slow and anisotropic conduction responsible for the restricted dimensions of the reentrant circuit. These findings may suggest a similar substrate and arrhythmia mechanism in the myocardium of the pulmonary veins.     

Sustained Bundle Branch Reentry in a Patient with Hypertrophic Cardiomyopathy and Nondilated Left Ventricle

Ventricular tachycardia is a well-known complication in patients withhypertrophic cardiomyopathy. We report the case of a patient withhypertrophic cardiomyo<->pathy with easily inducible monomorphic ventriculartachycardia. Electrophysiology study demonstrated that bundle branch reentrywas the mechanism of the tachycardia. The tachycardia was renderednon-inducible by radiofrequency ablation of the right bundle branch.     

Transitory or permanent regular wide QRS complex tachycardia induced by atrial stimulation in patients without apparent heart disease. Significance

Objectives. - The purpose of the study was to evaluate the frequency of transitory or permanent bundle branch block (BBB) associated with a paroxysmal tachycardia induced by atrial stimulation in patients without heart disease and its significance.Methods. - Esophageal atrial stimulation was performed in 447 patients suspected to have supraventricular tachycardias (SVT). Sustained regular tachycardia was induced in all of them but three, either in control state (75%) or after administering isoproterenol. In 346 patients, only narrow complex SVTs were induced (77%); in 259 of them, the reentry occurred in the AV node and in remaining patients within a concealed accessory pathway. In 62 patients, a transitory functional BBB was recorded at the onset of the tachycardia (14%). In 33 of them, the reentry occurred in the AV node and in the remaining 29 patients within a concealed accessory pathway. In 36 patients (8%), a permanently wide QRS complex tachycardia was induced. Three patients had also inducible narrow complex SVT. Atrial pacing induced a BBB similar to the aberrancy in tachycardia in 22 patients: the reentry occurred in the AV node in 17 patients, within a concealed accessory pathway in three patients and in a Mahaim bundle in two patients. In other patients, QRS complex remained normal during atrial pacing: all 14 patients had a ventricular tachycardia (VT), either a verapamil-sensitive VT (n = 7) or catecholamine-sensitive VT (n = 4) or bundle branch reentry (n = 3). Followed from 2 to 12 years, the prognosis of these patients was excellent.Conclusion. - Transitory BBB at the onset of an SVT is noted in 14% of the population, is more frequent in patients with accessory pathway reentrant tachycardia, but is helpful for this diagnosis in only 12% of cases. A regular tachycardia with permanent left or right bundle branch morphology induced by atrial stimulation in a patient without heart disease and without BBB during atrial pacing is due to a VT even if this patient has also narrow complex tachycardias. This mechanism does not affect the excellent prognosis of this population.     

Idiopathic Left Ventricular Tachycardia with Left and Right Bundle Branch Block Configurations

Fascicular Tachycardia. Introduction : Idiopathic left ventricular tachycardia typically has a right bundle branch block configuration. The purpose of this case report is to demonstrate that idiopathic ventricular tachycardia arising in or near the left posterior fascicle also may have a left bundle branch block configuration.
Methods and Results : A 27-year-old woman underwent an electrophysiologic procedure because of recurrent, verapamil-responsive, wide QRS complex tachycardia. Two types of ventricular tachycardia (cycle lengths 330 to 340 msec) were reproducibly inducible, one with a right bundle branch block configuration and left-axis deviation that had been documented clinically, and the other with a left bundle branch block configuration and axis of zero. A Purkinje potential recorded at the junction of the left ventricular mid-septum and inferior wall preceded the ventricular complex by 40 msec in both tachycardias. A single application of ra-diofrequency energy at this site successfully ablated both ventricular tachycardias.
Conclusion : The findings of this case report demonstrate that idiopathic ventricular tachycardia arising in or near the left posterior fascicle may have a left bundle branch block configuration     

Ventricular tachycardia with QRS configuration similar to that in sinus rhythm and a myocardial origin: differential diagnosis with bundle branch reentry.

INTRODUCTION: Tachycardia with a QRS configuration which resembles that in sinus rhythm is usually thought to be supraventricular. Ventricular tachycardia, with a similar QRS configuration to that in sinus rhythm on the 12-lead ECG, can occur. The mechanisms of this form of ventricular tachycardia have not been previously reported. METHODS AND RESULTS: The mechanism of ventricular tachycardia was defined during electrophysiological study in five patients. During sinus rhythm, all patients had a wide QRS complex (>0.12 s) on the 12-lead ECG. The morphology remained grossly unchanged during spontaneous, symptomatic tachycardia. Four of the five patients had coronary artery disease and left ventricular dysfunction. The remaining patient had idiopathic dilated cardiomyopathy. The relationship between the His bundle, deflection, the right bundle branch and the QRS complex was evaluated during tachycardia. Atrial and ventricular pacing, and ventricular activation mapping were performed during tachycardia to define the tachycardia mechanism. The tachycardia induced at electrophysiological testing, which was similar to the clinical tachycardia, was proven to be ventricular tachycardia in each patient. The morphology of ventricular tachycardia was right bundle branch block in two patients and left bundle branch block in three patients. The median tachycardia cycle length was 300 ms (range: 260-480 ms). His bundle activation occurred in a 1:1 relationship with ventricular activation during tachycardia in all patients at least intermittently. The tachycardias were thought initially to be bundle branch reentry tachycardia. With further intervention and continued observation, it became clear that His bundle activation was passive and was not required for the tachycardia to sustain. During tachycardia, His bundle activation appeared to precede the local ventricular activation. Instead, the His bundle was activated slowly from the previous ventricular beat causing a long ventricular-His (VH) interval. This was shown by: (1) activation patterns, (2) response to pacing, (3) intermittent VH dissociation, and (4) termination of ventricular tachycardia. CONCLUSION: A unique form of ventricular tachycardia is described. The QRS complex morphology on the 12-lead ECG during tachycardia was grossly similar to that during sinus rhythm. The His bundle activation was passive and occurred with a long activation time from the ventricle to the His bundle. Although it mimics usual bundle branch reentry, this form of ventricular tachycardia appears to be due to a different mechanism in which the His bundle is not obligatory for the continuation of the reentrant phenomenon.