Diagnostic clues from the surface ECG to identify idiopathic (fascicular) ventricular tachycardia: correlation with electrophysiologic findings

Belhassen Syndrome in Teenager Originating from Left Anterior Fascicle

A 16-year-old female patient was hospitalized due to narrow QRS tachycardia suggestive of fascicular ventricular tachycardia. Initially, the differential diagnosis with supraventricular tachycardia can be challenging. The tachyarrhythmia is well controlled with medication, but electrophysiological study and ablation may be necessary in patients who remain symptomatic.

Right bundle branch block-type wide QRS complex tachycardia with a reversed R/S complex in lead V6: Development and validation of electrocardiographic differentiation criteria

BACKGROUND

Differentiation of supraventricular tachycardia (SVT) with a right bundle branch block (RBBB) pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V₆ is below 1.0.

OBJECTIVE

We sought to investigate the electrocardiographic criteria for distinguishing between these arrhythmias.

METHODS

We investigated electrocardiographic parameters from 111 consecutive patients who had RBBB pattern wide QRS complex tachycardia with a reversed R/S ratio in lead V₆ (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS complex to the nadir of the S wave, divided by the QRS width in lead V₆. The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs).

RESULTS

The diagnostic accuracy of previous criteria (Brugada algorithm, Vereckei algorithm, and R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V₆ was significantly lower in SVT than in VT (0.36 ± 0.04 vs 0.50 ± 0.08; P < .001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity 97.2%; specificity 89.7%). When tested in a prospective population with fascicular VT, the diagnostic accuracy of the criteria was maintained (sensitivity 90.3%; specificity 86.2%).

CONCLUSION

The RS/QRS ratio >0.41 in lead V₆ is a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V₆. This criterion was particularly useful for the differential diagnosis of fascicular VT from RBBB pattern SVT.

Idiopathic Fascicular Left Ventricular Tachycardia

Idiopathic left fascicular ventricular tachycardia (ILFVT) is characterized by right bundle branch block morphology and left axis deviation. We report a case of idiopathic left ventricular fascicular tachycardia in a young 31-year-old male patient presenting with a narrow complex tachycardia.

Ventricular premature depolarizations triggered by incremental dose isoproterenol infusion: common electrocardiographic features

PURPOSE

To identify the prevalence of adrenergically mediated ventricular premature depolarizations (VPDs) and characterize their electrocardiographic (ECG) features and specific anatomically determined sites of origin within the ventricles.

METHODS

VPDs occurring during incremental isoproterenol infusion (3 to 20 mug/min) in 108 patients (30 women, mean age 58 +/- 10 years) with normal ventricular function and no previous ventricular tachycardia (VT) were identified. VPDs were grouped to a probable anatomic region of origin based on 12-lead ECG.

RESULTS

The 235 VPD morphologies (median 2 per patient, range 1-13) were observed in 85/108 (79%) patients. The most frequent regions of origin were: peri-mitral annulus 17%, left-Purkinje network 14%, right ventricle (RV) outflow tract 14%, apical RV free wall 11% and peri-tricuspid annulus 10%. Only 39 (17%) VPDs were not easily classified.

CONCLUSION

Adrenergically mediated VPDs are frequent in patients without structural heart disease or VT and tend to originate from a few anatomic sites.

Verapamil for ventricular tachycardia

Fascicular ventricular tachycardia (VT; also known as left VT) belongs to a subclass of idiopathic VTs. It can be confused with VT and supraventricular tachycardia. It is an entity well recognized by the cardiology community but not as frequently by emergency medicine physicians because of its infrequency. Idiopathic left VT was first described in 1979. Belhassen et al were the first to report on the characteristic termination of this VT with intravenous verapamil, hence accounting for the terms Belhassen VT and verapamil-responsive VT to describe the condition. We report on the cases of 2 patients who presented with complaints of palpitations. The first patient was incorrectly diagnosed with supraventricular tachycardia with aberrant conduction, whereas the second patient was correctly diagnosed with fascicular VT. Both cases were medically converted with verapamil. We also discuss the differentiation of ischemic VT and fascicular VT as well as the related therapeutic options and management approaches.

A case of a borderline-broad complex tachycardia

Prompt and correct treatment of broad complex tachycardias in the emergency department can often be life-saving to the patient and satisfying for the emergency physician. They, however, are often a diagnostic challenge. Here, we present a case of posterior fascicular ventricular tachycardia, an idiopathic form of ventricular tachycardia that occurs in patients without coronary artery disease and verapamil sensitive. The differential diagnoses of posterior fascicular ventricular tachycardia and supraventricular tachycardia with aberrancy will also be discussed.

Wide QRS complex tachycardia. Rapid method of prognostic evaluation

A wide QRS complex tachycardia suggests a ventricular tachycardia (VT); but supraventricular tachycardia (SVT) is also possible. Some authors reported on the electrocardiographic signs for the differential diagnosis of VT and SVT with aberrancy. Frequently these signs are debatable and the diagnosis is uncertain. The purpose of the study was to evaluate the interest of a non-invasive study by transesophageal route for the evaluation of the nature of a wide QRS complex tachycardia in which a reliable ECG algorithm does not permit to distinguish VT from SVT with aberrancy.

METHODS

Esophageal electrophysiologic study (EPS) was performed in 53 patients, aged from 16 to 85 years without bundle branch block (BBB) in sinus rhythm, but with wide-QRS tachycardia. The protocol consisted of atrial pacing at progressively higher rates and then programmed stimulation with one and two extrastimuli in control state and after isoproterenol infusion. Intracardiac EPS was performed in 49 of them.

RESULTS

(1) Study was negative in nine patients; intracardiac EPS remained negative in four of them, induced a VT in five; (2) clinical tachycardia was induced in 44 patients: (a) in 29 of them, atrial pacing induced a BBB similar to aberrancy noted in tachycardia and the diagnosis of SVT with aberrancy was made; (b) in 15 patients, QRS complex remained narrow during atrial pacing; the diagnosis of VT was made in presence of AV dissociation and confirmed by intracardiac study. VT was induced by atrial or ventricular stimulation or was spontaneous during isoproterenol infusion. VT mechanism were bundle branch reentry [Am. J. Cardiol. 65 (1990) 322], verapamilsensitive VT [Am. J. Cardiol. 65 (1990) 322], catecholamine-sensitive VT [J. Cardiovasc. Electrophysiol. 7 (1996) 2]. Two patients had tachycardias of both natures either supraventricular or ventricular.

CONCLUSION

Esophageal EPS was a safe, rapid and economic means to evaluate the mechanism of wide QRS tachycardia in 84% of patients; atrial pacing at progressively higher rates is very simple to reproduce the aberrancy of similar morphology in those patients who had wide-QRS tachycardia related to a SVT with aberrancy. If atrial pacing did not exactly reproduce the aberrancy in tachycardia, a VT should be suspected.

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.

[Contribution of the transesophageal electrophysiologic study to the etiologic diagnosis of wide QRS tachycardia]

INTRODUCTION

A wide-QRS complex tachycardia is suggestive of a ventricular tachycardia (VT). Its diagnosis requires an intracardiac electrophysiological study. That study is sometimes difficult to indicate in old or very young patients. The purpose of the study was to evaluate the interest of a rapid and noninvasive study by transesophageal route for the evaluation of the nature of a wide-QRS complex tachycardia.

PATIENTS AND METHODS

Forty patients, aged from 16 to 85 years, without bundle branch block (BBB) in sinus rhythm, were admitted for documented wide-QRS tachycardia. Transesophageal electrophysiologic study (EPS) using one and two extrastimuli was performed in control state and after infusion of 20/30 micrograms of isoproterenol. Intracardiac EPS was performed in a second time in 38 of them.

RESULTS

The study was negative six patients; intracardiac EPS remained negative in four of them, induced a VT in one and a Mahaim-reentrant supraventricular tachycardia in another one. Clinical tachycardia was induced in remaining patients: in 27 of them, the diagnosis of SVT with aberrancy was assessed; in other patients, the diagnosis of VT was assessed; The VT was a verapamil-sensitive VT or a bundle branch reentry (n = 7). The diagnosis was confirmed by intracardiac study.

CONCLUSION

Esophageal EPS was a means to reproduce the clinical tachycardia in 34 of 40 patients and to evaluate the mechanism of wide-QRS tachycardia in 33 of 34 patients; this technique easy to perform should be indicated in patients in whom intracardiac study is debatable to avoid to diagnose by excess a VT or in the opposite to miss this diagnosis.

Ventricular arrhythmias in normal hearts

Idiopathic ventricular tachycardia (VT) is characterized by two predominant forms. The most common form originates from the right ventricular outflow tract and presents as repetitive monomorphic VT or exercise-induced VT. The tachycardia is adenosine sensitive and is thought to be because of cAMP-mediated triggered activity. The other major form of idiopathic VT is owing to verapamil-sensitive intrafascicular re-entrant tachycardia, which most often originates in the region of the left posterior fascicle. Both forms of idiopathic VT can be readily treated with radiofrequency catheter ablation.

Fascicular ventricular tachycardia: an uncommon but distinctive form of ventricular tachycardia

Emergency physicians often encounter wide-QRS-complex tachyarrhythmias, which pose both a diagnostic and therapeutic challenge. Most such rhythms are the result of ventricular tachycardia (VT) related to coronary artery disease. However, the spectrum of VT is broad, with several distinct clinical entities, some of which are benign in their clinical course. Idiopathic fascicular VT is one such entity. We present two cases of idiopathic fascicular VT and discuss the unique electrocardiographic, electrophysiologic, and electropharmacologic properties that make it an identifiable and treatable arrhythmia in the ED.

Mechanisms of idiopathic left ventricular tachycardia

Idiopathic left ventricular tachycardia (ILVT) differs from idiopathic right ventricular outflow tract (RVOT) tachycardia with respect to mechanism and pharmacologic sensitivity. ILVT can be categorized into three subgroups. The most prevalent form, verapamil-sensitive intrafascicular tachycardia, originates in the region of left posterior fascicle of the left bundle. This tachycardia is adenosine insensitive, demonstrates entrainment, and is thought to be due to reentry. The tachycardia is most often ablated in the region of the posteroinferior interventricular septum. A second type of ILVT is a form analogous to adenosine-sensitive RVOT tachycardia. This tachycardia appears to originate from deep within the interventricular septum and exits from the left side of the septum. This form of VT also responds to verapamil and is thought to be due to cAMP-mediated triggered activity. A third form of ILVT is propranolol sensitive. It is neither or initiated or terminated by programmed stimulation, does not terminate with verapamil, and is transiently suppressed by adenosine, responses consistent with an automatic mechanism. Recognition of the heterogeneity of ILVT and its unique characteristics should facilitate appropriate diagnosis and therapy in this group of patients.

Predictors for successful ablation of right- and left-sided idiopathic ventricular tachycardia

This study reports on predictors for successful radiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) in 48 patients--35 with right ventricular (RV) outflow tract and 13 with left ventricular VT. In RV outflow tract idiopathic VT, RF ablation was successful in 29 of 35 patients (83%). The following information allowed differentiation between patients with and without a successful RF ablation: > 1 induced VT morphology (O vs 3); presence of delta wave-like beginning of the QRS (2 vs 3) and > or = 11 of 12 leads showing a "match" between the clinical VT and the pacemap (28 vs 1). Endocardial activation times were not different between both groups (-15 +/- 18 vs -4 +/- 5 ms). In left ventricle idiopathic VT, RF ablation was successful in 12 of 13 patients (92%). In patients who underwent successful ablation, 1 VT morphology was induced and no delta wave-like beginning of the QRS was present; a correlation between clinical VT and the pacemap > or = 11 of 12 leads was found and the endocardial activation time preceded the QRS (range of -5 to -58 ms [mean -30 +/- 14]). Purkinje activity was observed in 5 of 7 patients with an idiopathic VT originating from the inferoposterior region but not from the inferoapical region of the left ventricle. Four patients (14%) with RV outflow tract idiopathic VT had recurrence during a mean follow-up of 2 to 50 months (mean 30 +/- 12). Thus, (1) in RV outflow tract idiopathic VT a good pacemap was more important than an early endocardial activation time; (2) an optimal pacemap as well as an early endocardial activation time were important predictors for successful ablation of the left ventricle idiopathic VT; (3) Purkinje activity was recorded in VTs arising in the inferoposterior region of the left ventricle; and (4) factors for unsuccessful ablation for idiopathic VT were > 1 induced VT morphology, a delta wave-like beginning of the QRS, and a VT/pacemap correlation < 11 of 12 leads. Idiopathic VT can be successfully ablated with both immediate and long-term success.

Radiofrequency catheter ablation of idiopathic ventricular tachycardia originating in the anterior fascicle of the left bundle branch

INTRODUCTION

Idiopathic ventricular tachycardia (VT) originating in or close to the anterior fascicle of the left bundle is rare. A patient with no structural heart disease and VT with a right bundle branch block configuration and right-axis deviation underwent an electrophysiologic examination.

METHODS AND RESULTS

Both endocardial activation mapping during VT and pacemapping were performed via a transseptal approach to localize the site of origin of the VT. Endocardial recordings of the His bundle and the posterior and anterior fascicles of the left bundle branch revealed an origin of the VT in or close to the anterior fascicle. The Purkinje potential at that site preceded the QRS complex by 20 msec, with pacemapping showing an optimal match between the paced rhythm and the clinical VT. RF energy delivered at this site terminated the VT. A left anterior hemiblock appeared after RF ablation. Ten months later, the patient is free from recurrences of VT.

CONCLUSIONS

Idiopathic VT originating in or close to the anterior fascicle was cured by RF ablation. A Purkinje potential preceding the QRS during tachycardia and an optimal pacemap were used to guide RF ablation.