Radiofrequency catheter ablation of left ventricular outflow tract tachycardia: report of two cases

Discrepant effects of heart failure on electrophysiological property in right ventricular outflow tract and left ventricular outflow tract cardiomyocytes

Ventricular arrhythmias commonly arise from the right (RVOT) and left ventricular outflow tracts (LVOT) in patients without structural heart disease. Heart failure (HF) significantly increases the risk of ventricular arrhythmias. The regional differences and how HF affects the electrophysiological characteristics of RVOT and LVOT cardiomyocytes remain unclear. The whole-cell patch-clamp technique was used to investigate the action potentials and ionic currents in isolated single RVOT and LVOT cardiomyocytes from control rabbits and rabbits with HF induced by rapid ventricular pacing. Comparison with control LVOT cardiomyocytes showed that control RVOT cardiomyocytes have a shorter action potential duration (APD), smaller late Na+ currents (INa-late), larger transient outward (Ito) and larger delayed rectifier K+ currents (IKr-tail), but had similar L-type Ca2+ currents (ICa-L) and Na+/Ca2+ exchanger (NCX) current. HF increased APD, INa-late and NCX, but decreased ICa-L and Ito in RVOT cardiomyocytes. In contrast with this, HF decreased APD and ICa-L, but increased Ito and IKr-tail in LVOT cardiomyocytes. In conclusion, RVOT and LVOT cardiomyocytes had distinctive electrophysiological characteristics. HF differentially modulates action potential morphology and ionic currents in RVOT and LVOT cardiomyocytes.

Electrocardiogram features of premature ventricular contractions/ventricular tachycardia originating from the left ventricular outflow tract and the treatment outcome of radiofrequency catheter ablation

BACKGROUND

Radiofrequency catheter ablation (RFCA) has been used for the ablation of premature ventricular contractions (PVCs) or ventricular tachycardia (VT). To date, the mapping and catheter ablation of the arrhythmias originating from the left ventricular outflow tract (LVOT) has not been specified. This study investigates the electrocardiogram (ECG) feature of PVCs or VT originating from the LVOT. Moreover, the treatment outcome of RFCA is analyzed.

METHODS

Mapping and ablation were performed on the supravalvular or subvalvular aorta in 52 cases with PVCs/VT originating from the LVOT. The data were compared with those from 104 patients with PVCs/VT originating from the right ventricular outflow tract (RVOT). A differential procedure was prepared based on the comparison of the ECG features of PVCs/VT originating from the RVOT, LVOT, and their different parts.

RESULTS

Among 52 cases with PVCs originating from the LVOT, 47 were successfully treated by RFCA, with a success rate of 90.38%. Several differences among the 12-lead ECG features were observed from the RVOT and LVOT in the left and right coronary sinus groups, as well as under the left coronary sinus group (left fibrous trigone): (1) If the precordial leads transition <V3 plus the precordial leads transitional index >0 are considered as the diagnostic parameters of PVCs/VT originating from the LVOT, then the sensitivity, specificity, as well as positive and negative predictive values are 94.12%, 93.00%, 87.27%, and 96.88%, respectively; (2) The analysis of different subgroups of the LVOT are as follows: (a) A mainly positive wave of r or m pattern was recorded in the lead I in 72.73% of patients in the right coronary sinus group, versus 12.90% of patients in the left coronary sinus group, and 0% in the under left coronary sinus group. (b) All patients in the right coronary sinus group presented waves of RII>RIII and QSaVR>QSaVL, whereas most patients in the other two groups showed waves of RIII>RII and QSaVL>QSaVR. (c) Most patients in the under left coronary sinus group in lead V1 had a mainly positive wave (R) (77.78%), whereas those in the right (81.82%) and left (62.50%) coronary sinus groups had mainly negative waves (rS).

CONCLUSIONS

RFCA is a safe and effective curative therapy for PVCs/VT originating from the LVOT. The 12-lead ECG features of the LVOT from different origins exhibit certain distinctions.

Ablation of Idiopathic Ventricular Tachycardia in Two Separate Regions of the Outflow Tract: Prevalence and Electrocardiographic Characteristics

Few studies have clarified the prevalence and characteristics of idiopathic outflow tachycardia (OT-VT) with an altered QRS morphology after radiofrequency catheter ablation (RFCA), requiring additional RFCA applications at a different portion of the outflow tract (OT) to abolish the OT-VT. Among 344 patients (97 VTs and 247 premature ventricular contractions), 12 (3.5%; VTs-7, PVCs-5; 6 women) had dynamic QRS morphology changes following the RFCA, requiring additional RFCA applications at a different portion to abolish the OT-VT. In 8 of 12 patients (67%), this phenomenon occurred following RFCA at right (RVOT; n = 7) or left ventricular (LVOT; n = 1) endocardial sites of the OT: The second OT-VT was consistently associated with an increase in the R-wave amplitude in the inferior leads, and in five it was finally abolished by RFCA at the left sinus of Valsalva (LSV). Conversely, in four patients (33%), the second OT-VT appeared after RFCA at the LSV: two required additional RFCA applications at the LVOT to abolish the second OT-VT, and one at the RVOT, and all were associated with a decrease in the R-wave amplitude in the inferior leads. This kind of dynamic QRS morphology change was often observed when RFCA was applied to either the first or second OT-VT at a right or left ventricular endocardial site, with the other site being the LSV. A detailed continuous observation of the QRS morphology, especially of the R-wave in the inferior leads, is important for identifying changes in the QRS morphology during RFCA.

Idiopathic Left Ventricular Tachycardia Originating from the Mitral Annulus

BACKGROUND

Radiofrequency catheter ablation (RFCA) can eliminate most idiopathic repetitive monomorphic ventricular tachycardias (RMVTs) originating from the right and left ventricular outflow tracts (RVOT, LVOT). Here, we describe the electrophysiological (EP) findings of a new variant of RMVT originating from the mitral annulus (MAVT).

METHODS AND RESULTS

MAVT was identified in 35 patients out of 72 consecutive left ventricular RMVTs from May 2000 to June 2004. All patients underwent an EP study and RFCA. The sites of origin of the MAVT were grouped into four groups according to the successful ablation sites around the mitral annulus. Group I included the anterior sites (n = 11), group II the anterolateral sites (n = 9), group III the lateral sites (n = 6), and group IV the posterior sites (n = 9). The MAVTs were a wide QRS tachycardia with a delta wave-like beginning of the QRS complex. The transitional zone of the R wave occurred between V1-V2 in all cases. The 12-lead electrocardiogram (ECG) pattern might reflect the site of the origin of MAVTs around the mitral annulus. We proposed an algorithm for predicting the site of the focus and the tactics needed for successful RFCA of the MAVT.

CONCLUSIONS

We described the EP findings of the new variant of RMVT, MAVT. Most MAVTs could be eliminated by RF applications to the endocardial mitral annulus using our proposed tactics.

Idiopathic ventricular arrhythmia arising from the mitral annulus

OBJECTIVES

We sought to clarify the prevalence and characteristics of idiopathic ventricular tachycardia or premature ventricular contraction originating from the mitral annulus (MAVT/PVC).

BACKGROUND

Recent case reports have presented patients with MAVT/PVC.

METHODS

Electrocardiographic (ECG) characteristics and the results of electrophysiologic investigation and radiofrequency catheter ablation (RFCA) were analyzed in 352 patients with symptomatic idiopathic ventricular tachycardia (IVT)/premature ventricular contraction (PVC).

RESULTS

Nineteen cases of IVT/PVC (5%) represented MAVT/PVC. Of these, 11 (58%) originated from the anterolateral portion of the mitral annulus (AL-MAVT/PVC), and 2 (11%) arose from the posterior portion (Pos-MAVT/PVC). The remaining six cases of MAVT/PVC (31%) had posteroseptal origin (PS-MAVT/PVC). In all patients, an S-wave was present in lead V(6). The QRS polarity in inferior leads and leads I and aVL was useful for differentiating AL-MAVT/PVC from Pos-MAVT/PVC or PS-MAVT/PVC. The Pos-MAVT/PVC had an Rs pattern in lead I and an R pattern in lead V(1), whereas PS-MAVT/PVC invariably had an R pattern in lead I and a negative QRS component in lead V(1). The AL-MAVT/PVC and Pos-MAVT/PVC showed a longer QRS duration than the PS-MAVT/PVC (p < 0.001), and all had late-phase "notching" of the QRS complex in inferior leads. In all patients, RFCA eliminated MAVT/PVC, with no recurrences during follow-up for 21 +/- 15 months.

CONCLUSIONS

Mitral annular VT/PVC is a rare but distinct subgroup of IVT/PVC. MAVT/PVC origin could be determined by ECG analysis. The AL and PS sites of the MA were preferential.

Prevalence and Characteristics of Idiopathic Outflow Tract Tachycardia with QRS Alteration Following Catheter Ablation Requiring Additional Radiofrequency Ablation at a Different Point in the Outflow Tract

Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.

Development and Validation of an ECG Algorithm for Identifying the Optimal Ablation Site for Idiopathic Ventricular Outflow Tract Tachycardia

INTRODUCTION

Idiopathic ventricular outflow tract tachycardia or premature ventricular contractions (OT-VTs) can originate from several different sites in the outflow tract, including the left ventricular (LV) endocardium and epicardium. The aims of this study were (1) to develop an ECG algorithm to predict the origin of OT-VT and (2) to test prospectively the accuracy of the algorithm.

METHODS AND RESULTS

An algorithm was developed by correlating the 12-lead ECG findings with the catheter ablation site in 80 patients with OT-VT. The ECG characteristics of the QRS complex during the arrhythmia were analyzed. The catheter sites were verified by multi-plane fluoroscopy. The outflow tract was classified into six subdivisions: right ventricular (RV) septum, RV free wall, RV near the His-bundle region, LV endocardium, left sinus of Valsalva (LSV), and LV epicardium remote from the LSV. An OT-VT originating from the LV epicardium remote from the LSV was defined as an OT-VT in which the earliest ventricular activation was recorded at the LSV and radiofrequency ablation from the LSV failed. This algorithm subsequently was tested prospectively in 88 patients. Overall sensitivity was 88% and specificity was 95%. The positive and negative predictive values were 88% and 96%, respectively.

CONCLUSION

We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions.

Electrocardiographic characteristics of ventricular arrhythmias arising from the aortic sinuses of valsalva: a case report and review of the literature

We describe a patient with frequent, symptomatic, and drug-refractory premature ventricular contractions (PVCs) with a right bundle branch block, inferior axis morphology suggestive of a left ventricular outflow tract (LVOT) origin. Successful ablation of the PVCs was performed from the left coronary cusp of the aortic valve. We discuss our patient and review the literature regarding patients with ventricular arrhythmias arising from the coronary cusps, with special emphasis on the use of the electrocardiogram to aid localization of the focus.

Surgical cryoablation for frequent premature ventricular contraction originating in the left sinus of Valsalva

Cryoablation in the left ventricular outflow tract and aortic valve replacement were conducted in a 70-year-old man with frequent premature ventricular contraction and nonsustained ventricular tachycardia complicated by Sellers grade 4 aortic regurgitation. The earliest endocardial activation site during premature ventricular contraction was confirmed by a preoperative electrophysiological study of the left sinus of Valsalva. Cryoablation preceded valvulectomy followed by aortic valve replacement. Clinical symptoms of premature ventricular contraction disappeared immediately after surgery.

Radiofrequency catheter ablation from the left sinus of Valsalva in a patient with idiopathic ventricular tachycardia

We report the case of a 54-year-old woman with idiopathic VT originating in the left ventricular outflow tract. She initially presented with palpitations and light-headedness. The morphology of the PVCs exhibited an inferior axis and tall R waves were noted in all the precordial leads. Spontaneous PVCs were transiently terminated by an intravenous injection of adenosine triphosphate. Radiofrequency catheter ablation from the left sinus of Valsalva successfully abolished the PVCs and the VT.

Successful radiofrequency catheter ablation from the supravalvular region of the aortic valve in a patient with outflow tract ventricular tachycardia

Outflow tract ventricular tachycardia (OT-VT) was successfully ablated from the right coronary cusp of the aortic valve. The 12-lead ECG was totally different from the typical right ventricular OT-VT because the R/S ratio in precordial lead V1 was equal to 1 and tall R waves in precordial leads V2-6 were seen. Radiofrequency energy application from the right coronary cusp of the aortic valve successfully ablated this VT without complications. Radiofrequency catheter ablation from the right coronary cusp of the aortic valve can be done safely and effectively.

Catheter ablation of repetitive monomorphic ventricular tachycardia from left ventricular outflow tract guided by unipolar mapping

Repetitive monomorphic ventricular tachycardia from the left ventricular outflow tract is an uncommon arrhythmia. Successful catheter ablation has been previously reported in a few cases, but a large number of applications were usually needed when an approach based on either activation mapping or pace mapping was used. In our patient, the selection of the target point for application was based exclusively on unipolar mapping criteria of the ectopic beats, resulting in a short procedure with successful outcome.

Left ventricular tachycardia originating near the left main coronary artery

Eight patients with idiopathic ventricular tachycardia (VT) underwent mapping and radiofrequency ablation. Mapping showed VT originating in the high posterolateral left ventricular outflow tract in proximity to the left main and proximal circumflex coronary arteries. Ablation was not attempted due to this proximity to the left main and proximal circumflex coronary arteries. Ablation was not attempted due to this proximity in 2 patients and limited in 1 patient. It was successful in VT suppression in 5 of 6 patients.

Successful treatment of idiopathic left ventricular outflow tract tachycardia by catheter ablation or minimally invasive surgical cryoablation

Idiopathic right ventricular outflow tract tachycardia is readily amenable to radiofrequency catheter ablation. However, treatment modalities for left ventricular outflow tract tachycardia are not well defined. Out of 37 patients with idiopathic outflow tract tachycardia referred for catheter ablation, in 3 patients tachycardia originated from the left ventricular outflow tract. On the surface ECG, all left ventricular tachycardias exhibited an inferior axis with a predominant negative QRS complex in lead I. Heart rate during tachycardia ranged from 115 to 170 beats/min. During electrophysiological testing, 1 patient had inducible tachycardia on orciprenaline challenge, 1 patient had inducible tachycardia at baseline, and 1 patient had incessant tachycardia. In two patients, earliest ventricular activation was recorded from the endocardial left ventricular outflow tract at an anterolateral and an anterior site, respectively. A distinct high frequency spike preceded the QRS onset by 66/78 ms. Application of radiofrequency energy successfully eliminated tachycardia at these sites. In one patient, tachycardia originated from the epicardial left ventricular outflow tract. Mapping of the anterior interventricular vein revealed a fractionated low amplitude signal occurring 46 ms before QRS onset. After failure of catheter ablation from the corresponding endocardial site, successful minimally invasive surgical focal cryoablation of the epicardial target region was performed. During a follow-up period ranging from 7 to 12 months, all patients remained free of tachycardia. In conclusion, ventricular tachycardia arising from the left ventricular outflow tract may require endo- and epicardial mapping. Successful treatment is achieved by radiofrequency catheter ablation or minimally invasive surgical cryoablation.

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.

Radiofrequency catheter ablation of ventricular tachycardia from the anterobasal left ventricle

Ventricular tachycardia (VT) in coronary artery disease arises mostly from endocardial sites. However, little is known about the site of origin in other diseases. We report two patients who had VT originating from an anterior aspect of the left ventricle just below the mitral annulus, adjacent to the left ventricular outflow tract. The QRS configuration of VT showed an inferior axis and monophasic R waves in all the precordial leads. Radiofrequency current delivered to this site from the endocardial site successfully ablated the tachycardia in both.

Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology

Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.

Dual morphology of idiopathic ventricular tachycardia

INTRODUCTION

Idiopathic ventricular tachycardia (VT) typically has a single morphology originating either in the right ventricular outflow tract (RVOT) or near the posterior fascicle of the left ventricle (LV) in most instances. We present our observations in six patients with idiopathic VT in whom two morphologies were present.

METHODS AND RESULTS

Of 55 patients with idiopathic VT who underwent radiofrequency (RF) ablation, 44 had LV "fascicular" tachycardia, whereas 11 had RVOT tachycardia. During RF energy delivery, there was a change in VT morphology in two patients with idiopathic LV tachycardia. This second morphology was not ablated initially, recurred at follow-up, and was reablated successfully. In two additional patients with idiopathic LV tachycardia, a second VT was inducible after ablation of the "clinical" VT. This second morphology recurred at follow-up and was ablated successfully in one patient. The site where the second VT was ablated in all the three patients was remote from that of the first VT. In two patients with RVOT tachycardia, a second VT, originating from a different area of the RVOT, was induced after RF ablation of the "clinical" VT. This second VT recurred at follow-up and was reablated successfully in one patient.

CONCLUSION

Idiopathic VT is a more heterogenous entity than hitherto believed. A second VT was seen in 11% of patients during or after RF ablation of the "clinical" VT. The appearance of a second VT suggests either a different exit site of the same circuit or another site of origin.

Heart rate variability analysis of patients with idiopathic left ventricular outflow tract tachycardia: role of triggered activity

There have been several reports with respect to idiopathic ventricular tachycardias (VTs) originating from the left ventricular outflow tract (LVOT). A previous report suggested that triggered activity plays a partial role in idiopathic LVOT tachycardia from the electrophysiological as well as the electropharmacological viewpoint. However, the exact role of triggered activity in this type of VT remains unknown. In the present study the relationship of the frequency of premature ventricular contractions (PVCs) and heart rate was examined and heart rate variability (HRV) was analyzed in 2 cases of LVOT tachycardia using 24-h Holter electrocardiographic (ECG) monitoring. The relation between the PVCs frequency and heart rate showed a persistently positive correlation, indicating frequent PVCs as heart rate increased. In HRV analysis, NN50(%), a time-domain variable of parasympathetic activity, showed no change prior to ventricular arrhythmias. In frequency-domain analysis of HRV, the high frequency (HF) component tended to fall prior to repetitive PVCs and VTs. The ratio of the low frequency to high frequency (LF/HF) components increased prior to single PVCs, repetitive PVCs and VTs. Sympathetic predominance predisposes the genesis of these kinds of arrhythmias originating from the LVOT and it is suggested that triggered activity plays an important role in LVOT tachycardia, at least in its initiation.

Radiofrequency catheter ablation of left ventricular outflow tract tachycardia from the coronary cusp: a new approach to the tachycardia focus

INTRODUCTION

Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during VT exhibited an atypical left bundle branch block and inferior axis. Pace mapping revealed that the origin of this VT was very close to the left sinus of Valsalva. Transcoronary cusp RF catheter ablation abolished the VT in this patient and is a new approach for the treatment of this kind of VT. The application of this approach to the other types of VT has yet to be determined.