Radiofrequency Ablation Guided by Mechanical Termination of Idiopathic Ventricular Arrhythmias Originating in the Right Ventricular Outflow Tract

Mapping of Idiopathic Ventricular Arrhythmias. Background: Termination of ventricular tachycardia (VT) by mechanical pressure has been described for fascicular and postinfarction VT. Mechanical interruption of idiopathic ventricular arrhythmias (VT/premature ventricular complexes [PVCs]) arising in the right ventricular outflow tract (RVOT) has not been described in systematic fashion. Methods: Eighteen consecutive patients (13 females, age 49 ± 13 years, ejection fraction 0.55 ± 0.12) underwent mapping and ablation of RVOT VT or PVCs. In 7 patients, 9 distinct VTs (mean cycle length 440 ± 127 ms), and in 11 patients, 11 distinct PVCs originating in the RVOT were targeted. Mechanical termination was considered present if a reproducibly inducible VT was no longer inducible or if frequent PVCs suddenly ceased with the mapping catheter at a particular location. Endocardial activation time, electrogram characteristics, and pace‐mapping morphology were assessed at this location. Radiofrequency energy was delivered if mechanical termination was observed. Results: All targeted arrhythmias were successfully ablated. In 7 of 18 patients (39%), catheter manipulation terminated the arrhythmia with the mapping catheter located at a particular site. Local endocardial activation time was earlier at sites of mechanical termination (?31 ± 7 ms) compared with effective sites without termination (?25 ± 3 ms, P = 0.04). The 10‐ms isochronal area was smaller in patients with mechanical interruption (0.35 ± 0.2 cm²) than in patients without mechanical termination (1.33 ± 0.9 cm², P = 0.01). At all sites susceptible to mechanical trauma, the pace map displayed a match with the targeted VT/PVC. All sites where mechanical termination of VT or PVCs occurred were effective ablation sites. Conclusions: Mechanical suppression at the site of origin of idiopathic RVOT arrhythmias frequently occurs during the mapping procedure and is a reliable indicator of effective ablation sites. Mechanical termination of RVOT arrhythmias may be indicative of a more localized arrhythmogenic substrate. (J Cardiovasc Electrophysiol, Vol. 21, pp. 42–46, January 2010)     

Catheter ablation of ventricular arrhythmias arising from the right ventricular septum close to the His bundle: features of the local electrogram at the optimal ablation site

Ablation of Para‐Hisian Ventricular Arrhythmias . Introduction: The characteristics of the local electrogram at the optimal ablation site of ventricular arrhythmias (VAs) originating from the right ventricle close to the His bundle (HB) region have rarely been described. Methods and Results: Among 190 consecutive patients with idiopathic VAs with left bundle branch block morphology and inferior‐axis deviation, 16 were found to have successful ablation site in the right ventricle close to the HB region (para‐Hisian group). The electrophysiologic data were compared between the patients in the para‐Hisian group and those with VAs arising from the right ventricular (RV) outflow tract (RVOT group). The distal bipolar electrogram at the successful ablation sites in the para‐Hisian group exhibited a significantly greater R‐wave duration, lower R‐wave amplitude, and slower upright deflection of the initial R wave than did those in the RVOT group (all P < 0.001). In the para‐Hisian group, a total of 56 radiofrequency (RF) energy applications were delivered, of which the local electrograms at 16 successful and 40 unsuccessful ablation sites were reviewed. High‐frequency R‐wave potentials of the bipolar electrogram were present in 14 (88%) of the successful ablation sites. An R‐wave duration of greater than 34 ms had a discriminatory power for indicating the site of a successful ablation (area under the receiver–operator characteristics curve 0.90, sensitivity 94%, specificity 80%). Conclusions: The successful ablation site of the para‐Hisian VAs had distinctive local electrogram characteristics. A longer R‐wave duration of the bipolar electrogram with high‐frequency potentials could be a novel predictor of a successful ablation. (J Cardiovasc Electrophysiol, Vol. 22, pp. 878‐885, August 2011)     

Endocardial mapping of right ventricular outflow tract tachycardia using noncontact activation mapping

INTRODUCTION: Activation mapping and pace mapping identify successful ablation sites for catheter ablation of right ventricular outflow tract (RVOT) tachycardia. These methods are limited in patients with nonsustained tachycardia or isolated ventricular ectopic beats. We investigated the feasibility of using noncontact mapping to guide the ablation of RVOT arrhythmias. METHODS AND RESULTS: Nine patients with RVOT tachycardia and three patients with ectopic beats were studied using noncontact mapping. A multielectrode array catheter was introduced into the RVOT and tachycardia was analyzed using a virtual geometry. The earliest endocardial activation estimated by virtual electrograms was displayed on an isopotential color map and measured 33 +/- 13 msec before onset of QRS. Virtual unipolar electrograms at this site demonstrated QS morphology. Guided by a locator signal, ablation was performed with a mean of 6.9 +/- 2.2 radiofrequency deliveries. Acute success was achieved in all patients. During follow-up, one patient had a recurrence of RVOT tachycardia. Compared with patients (n = 21) who underwent catheter ablation using a conventional approach, a higher success rate was achieved by noncontact mapping. Procedure time was significantly longer in the noncontact mapping group. Fluoroscopy time was not significantly different in the two groups. CONCLUSION: Noncontact mapping can be used as a reliable tool to identify the site of earliest endocardial activation and to guide the ablation procedure in patients with RVOT tachycardia and in patients with ectopic beats originating from the RVOT.     

Endocavitary Structures in the Outflow Tract: Anatomy and Electrophysiology of the Conus Papillary Muscles

Catheter ablation is an increasingly used and successful treatment choice for right ventricular outflow tract (RVOT) arrhythmias. While the role of endocavitary structures and the regional morphology of the ventricular inflow tract and the right atrium as a cause for difficulty with successful ablation are well described, similar issues within the RVOT are not well understood. It is also not commonly appreciated that one of the papillary muscles is located within the proximal RVOT. We report 3 patients in which ventricular arrhythmia was targeted and ablated in the conus papillary muscle. The anatomic features, potential role of the fascicular conduction system, and unique challenges with mapping arrhythmia arising from this structure are discussed.     

Electroanatomic mapping characteristics of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia.

BACKGROUND: Ventricular tachycardia (VT) in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVD) has been previously explored using entrainment mapping techniques but little is know about VT mechanisms and the characteristics of their circuits using an electroanatomical mapping system. METHODS AND RESULTS: Three-dimensional electroanatomical mapping was performed in 11 patients with well tolerated sustained VT and ARVD. Sinus rhythm mapping of the right ventricle was performed in eight patients showing areas of low bipolar electrogram voltage (<1.2 mV). In total 12 tachycardias (mean cycle length 382+/-62 ms) were induced and mapped. Complete maps demonstrated a reentry mechanism in eight VTs and a focal activation pattern in four VTs. The reentrant circuits were localized around the tricuspid annulus (five VTs), around the right ventricular outflow tract (one VT) and on the RV free lateral wall (two VTs). The critical isthmus of each peritricuspid circuit was bounded by the tricuspid annulus with a low voltage area close to it. The isthmus of tachycardia originating from the right ventricular outflow tract (RVOT) was delineated by the tricuspid annulus with a low voltage area localized on the posterior wall of the RVOT. Each right ventricular free wall circuit showed an isthmus delineated by two parallel lines of block. Focal tachycardias originated on the right ventricular free wall. Linear radiofrequency ablation performed across the critical isthmus was successful in seven of eight reentrant tachycardias. The focal VTs were successfully ablated in 50% of cases. During a follow-up of 9-50 months VT recurred in four of eight initially successfully ablated VTs. CONCLUSIONS: Peritricuspid ventricular reentry is a frequent mechanism of VT in patients with ARVD which can be identified by detailed 3D electroanatomical mapping. This novel form of mapping is valuable in identifying VT mechanisms and in guiding RF ablation in patients with ARVD.     

Mapping and Ablating Ventricular Premature Contractions That Trigger Ventricular Fibrillation: Trigger Elimination and Substrate Modification

Ventricular fibrillation (VF) is a malignant arrhythmia, usually initiated by a ventricular premature contraction (VPC) during the vulnerable period of cardiac repolarization. Ablation therapy for VF has been described and increasingly reported. Targets for VF triggers are VPC preceded Purkinje potentials or the right ventricular outflow tract (RVOT) in structurally normal hearts, and VPC triggers preceded by Purkinje potentials in ischemic cardiomyopathy. The most important issue before the ablation session is the recording of the 12‐lead electrocardiogram (ECG) of the triggering event, which can prove invaluable in regionalizing the origin of the triggering VPC for more detailed mapping. In cases where the VPC is not spontaneous or inducible, ablation may be performed by pacemapping. During the session, mapping should be focused on the earliest activation and determining the earliest potential is the key to a successful ablation. However, a modification of the Purkinje network might be applied when the earliest site cannot be determined or is located close to the His‐bundle. Furthermore, the electrical isolation of the pulmonary artery (PA) can suppress RVOT type polymorphic ventricular tachycardia in some patients with rapid triggers from the PA. Suppression of VF can be achieved by not only the elimination of triggering VPCs, but also by substrate modification of possible reentry circuits in the Purkinje network, or between the PA and RVOT. Further studies are needed to evaluate the precise mechanisms of this arrhythmia.     

Electrocardiographic and electrophysiologic characteristics of ventricular tachycardia originating within the pulmonary artery

OBJECTIVES: We investigated the electrocardiographic (ECG) and electrophysiologic characteristics of ventricular tachycardia (VT) originating within the pulmonary artery (PA). BACKGROUND: Radiofrequency catheter ablation (RFCA) is routinely applied to the endocardial surface of the right ventricular outflow tract (RVOT) in patients with idiopathic VT of left bundle branch block morphology. It was recently reported that this arrhythmia may originate within the PA. METHODS: Activation mapping and ECG analysis were performed in 24 patients whose VTs or ventricular premature contractions (VPCs) were successfully ablated within the PA (PA group) and in 48 patients whose VTs or VPCs were successfully ablated from the endocardial surface of the RVOT (RV-end-OT group). RESULTS: R-wave amplitudes on inferior ECG leads, aVL/aVR ratio of Q-wave amplitude, and R/S ratio on lead V(2) were significantly larger in the PA group than in the RV-end-OT group. On intracardiac electrograms, atrial potentials were more frequently recorded in the PA group than in the RV-end-OT group (58% vs. 12%; p < 0.01). The amplitude of local ventricular potentials recorded during sinus rhythm within the PA was significantly lower than that recorded from the RV-end-OT (0.62 +/- 0.56 mV vs. 1.55 +/- 0.88 mV; p < 0.01). CONCLUSIONS: Ventricular tachycardia originating within the PA has different electrocardiographic and electrophysiologic characteristics from that originating from the RV-end-OT. When mapping the RVOT area, the catheter may be located within the PA if a low-voltage atrial or local ventricular potential of <1-mV amplitude is recorded. Heightened attention must be paid if RFCA is required within the PA.     

右室流出道心律失常的发作方式与单导管消融治疗

报道 33例右室流出道心律失常的发作方式与单导管消融治疗。 3例仅室性早搏 (简称室早 )发作 ,30例室早与室性心动过速 (简称室速 )或心室颤动 (简称室颤 )并存。其中室早合并短阵单形室速 17例 ,合并持续单形室速 6例 ,合并多形室速 4例 ,合并快速室速或心室扑动 2例 ,合并室颤 1例。单点穿刺股静脉后 ,行右房或心室造影 ,将单根多枚电极导管按需放置于右室心尖部或流出道 ,行电生理检查、起搏与激动顺序标测和消融治疗。结果 :消融成功 30例 ,成功率 91%。靶点电图较体表QRS波始点早 38± 12 .4ms。 12例成功靶点位于右室流出道游离壁、9例位于间隔部、5例在游离壁和间隔部作多点片状消融、3例位于肺动脉瓣上、1例在右室流出道间隔部和左室间隔部消融成功。操作时间 5 2± 2 2 .2min ,X线透照时间 2 6± 18.0min ,放电时间 373± 111.7s。术中 1例未诱发心律失常 ,未行消融。 3例发生并发症 ,2例终止消融。 1例右室流出道穿孔 ,心包压塞。 1例多形室速 ,消融中室早多次触发室颤。 1例剧烈胸痛 ,冠状动脉造影示前降支近端 5 0 %局限狭窄。随访 14± 4 .5个月 ,无死亡病例 ,3例复发 ,1例消融 3次均复发 ,复发率 10 %。住院总花费人均 9133± 12 0 0元。结论 :右室流出道心律失常发病形式多种多样 ,单导?     

峰电位和舒张期电位对主动脉窦起源室性早搏射频消融的意义

目的 应用三维电解剖标测（Carto）系统探讨峰电位和舒张期电位对主动脉窦起源室性早搏射频消融的指导意义.方法 本研究病例为2009年5月至2012年2月流出道室性早搏射频消融125例,起源于主动脉窦（aortic sinus cusp,ASC）21例;在Carto系统下构建右心室流出道和/或左心室流出道三维解剖图,激动标测结合起搏标测对所有患者行射频消融治疗,观察峰电位和舒张期电位与成功消融靶点的关系.结果 21例患者射频消融成功,其中左冠窦17例,右冠窦2例,无冠窦2例.体表心电图特点：右束支阻滞图形7例为A组,左束支阻滞图形14例为B组.A组ASC最早激动点V波提前于体表心电图QRS波（earliest ventricular activation,EVA） 22 ～ 34（27.4±4.6）ms,B组右心室流出道EVA：22～38（27.4±5.2）ms,主动脉窦内EVA：18 ～40（25.9±6.0）ms,其中9例激动时间右心室流出道较冠状窦内提前,右侧起搏标测相似度90％以上.有17例患者在靶点处标测到峰电位,有19例患者在靶点附近标测到舒张期电位,舒张期电位呈区域性分布,面积1.0～ 1.5 cm2.16例记录到峰电位和舒张期电位,由Carto系统可见峰电位位于舒张期电位区域边缘,在峰电位处消融成功,1例记录到峰电位但未记录到舒张期电位,在峰电位处消融成功,3例只记录到舒张期电位,在舒张期电位区域内消融成功,只有1例既无峰电位又无舒张期电位.结论 峰电位与舒张期电位对主动脉窦起源室性早搏的射频消融具有指导意义.     

Idiopathic ventricular arrhythmias arising from the pulmonary artery: Prevalence, characteristics, and topography of the arrhythmia origin

BACKGROUND: The characteristics of idiopathic ventricular tachycardias (VTs) or idiopathic premature ventricular contractions (PVCs) arising from the pulmonary artery (PA) have not been sufficiently clarified. OBJECTIVE: The purpose of this study was to clarify the prevalence, characteristics, and preferential sites of idiopathic VT/PVCs arising from the PA (PA-VT/PVCs). METHODS: Data obtained from 276 patients with idiopathic VT/PVCs who underwent radiofrequency (RF) catheter ablation were analyzed. RESULTS: Twelve VT/PVCs (4%) were PA-VT/PVCs, and their onset (34 +/- 14 years) was the youngest among all subgroups. Because those QRS morphologies were similar to VT/PVCs arising from the right ventricular outflow tract (RVOT-VT/PVC) and the earliest ventricular activation was from the RVOT, an initial ablation was performed in the RVOT in all patients. However, RF catheter ablation at the RVOT resulted in a QRS morphology change in all patients, so thereafter PA mapping and ablation was performed. A characteristic potential during sinus rhythm and/or the arrhythmia was recorded at the successful PA ablation site in all patients. A perfect or good pace map was obtained in 7 (70%) of 10 patients. The successful ablation site was the septal side of the PA close to the posterolateral attachment in 9 patients (75%) and the septal side close to the anterior attachment in the remaining 3 (25%). No PA-VT/PVCs recurred during follow-up of 27 +/- 13 months. CONCLUSION: PA-VT/PVCs should always be considered when the ECG suggests RVOT-VT/PVCs and RF catheter ablation in the RVOT results in both a failed ablation and a change in QRS morphology. PA-VT/PVCs often originate from the septal side of the PA.     

EnSite Velocity 系统指导单导管射频导管消融右心室流出道室性期前收缩的初步体会

目的：探讨EnSite Velocity系统指导单导管射频消融（RFCA）治疗右心室流出道（ROVT）室性期前收缩（PVCs）的可行性。方法28例药物未能控制的ROVT PVCs患者行单导管消融术,消融导管在EnSite Velocity系统指导下进行解剖标测重建RVOT模型,经激动顺序标测及起搏标测明确消融靶点。结果 RVOT建模时间及所需X线曝光时间为（6.6±2.2） min、（0.5±0.4）min。即刻消融成功率100%,异位起搏点起源自间隔部17例（60.7%）、前壁3例、后壁3例、游离壁5例。消融靶点较体表QRS波群起点提前（34.2±5.1）ms。手术总时间、总X线曝光时间、标测时间、消融时间分别为（56.2±13.9）min、（1.1±0.7）min、（15.5±8.2）min、（5.5±2.9）min,其中6例零X线曝光。术中、术后没有相关并发症出现,观察（19.7±8.6）d,复发1例。结论 RVOT PVCs多起源于间隔部,经EnSite Velocity系统指导的单导管消融安全有效。     

Ablation of Ventricular Arrhythmias in Arrhythmogenic Right Ventricular Dysplasia

VT Ablation in Right Ventricular Dysplasia. Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically determined myocardial disease characterized by fibrofatty replacement of the right ventricular wall. Ventricular tachyarrhythmias can be seen in the early stages of the disease, which is one of the most important causes of sudden death in young healthy individuals. Radiofrequency (RF) catheter ablation is an option for the treatment of medically refractory ventricular arrhythmias and it has shown to successfully abolish recurrent ventricular tachycardias (VT) as well as reduce the frequency in defibrillator therapies. However, variable acute and long‐term success rates have been reported. The current mapping and ablation techniques include activation and entrainment mapping during tolerated VT and substrate ablation using 3‐dimensional electroanatomic mapping systems. This article aims at providing a comprehensive review of RF catheter ablation of ventricular arrhythmias in the context of ARVD. (J Cardiovasc Electrophysiol, Vol. 21, pp. 473‐14, April 2010)     

A quantitative and qualitative analysis of the virtual unipolar electrograms from non-contact mapping of right or left-sided outflow tract premature ventricular contractions/ventricular tachycardia origins

Objective

This study was conducted to examine the virtual unipolar electrogram configuration of right/left outflow tract (OT) premature ventricular contraction (PVC)/ventricular tachycardia (VT) origins obtained from a non-contact mapping system (NCMS).

Methods

The subjects consisted of 30 patients with OT-PVCs/VT who underwent NCMS-guided ablation. We evaluated the virtual unipolar electrograms of the origin on 3D right ventricular (RV)-OT isochronal maps.

Results

Successful ablation was achieved from the RV in 20 patients (RVOT group), and it failed in 10 (non-RVOT group: including left-sided/pulmonary artery/deep RVOT foci). On the virtual unipolar electrograms, the earliest activation (EA) preceded the QRS onset by 11.2?±?2.6 ms in the RVOT group and by 7.4?±?10.5 ms in the non-RVOT group (P?=?0.138). The negative slope of the electrogram at the EA site (EA slope₅), quantified by the virtual unipolar voltage amplitude 5 ms after the EA onset, was significantly steeper in the RVOT group than in the non-RVOT group (0.66?±?0.52 mV vs. 0.14?±?0.17 mV, P?=?0.005). Cutoff values for the EA-to-QRS onset time and EA slope₅ of ??8 ms and >0.3 mV, respectively, completely differentiated the RVOT group from the non-RVOT group. A lesser EA slope₅ was associated with a greater radiofrequency energy delivery required to terminate RVOT-PVCs/VT.

Conclusions

These demonstrate the importance of the virtual unipolar electrograms from OT-PVC/VT origins obtained with the NCMS. The virtual EA predicts both successful and potentially difficult ablation sites from the RV side.     

Electrocardiographic characteristics of repetitive monomorphic right ventricular tachycardia originating near the His-bundle

INTRODUCTION: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His-bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His-bundle in comparison with right ventricular outflow tract (RVOT)-VT/VPCs. METHODS AND RESULTS: Ninety RV-VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His-bundle. Ten patients had foci near the His-bundle (HIS group), with the His-bundle local ventricular electrogram preceding the QRS onset by 15-35 msec (mean: 22 msec) and His-bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 +/- 0.6 mV) was significantly lower than that of the RVOT group (1.7 +/- 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group. CONCLUSION: VT/VPCs originating near the His-bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation.     

特发性室性心律失常的射频消融

目的特发性室性心律失常（IVA）是指不伴有明显器质性心脏病的室性心动过速（室速）或室性早搏（室早）,约占所有室性心律失常的10％左右。本文系统分析925例IVA病例,探讨IVA的临床、电生理和射频消融的特点。方法本文回顾性分析了从1994年3月至2009年2月,925例IVA患者的临床特点,射频消融治疗的过程和结果。925例病人,男性500例,女性425例,平均年龄（36．65±14．81）岁。临床证实为IVA患者,并且排除了器质性心脏病。在停用抗心律失常药物5个半衰期后,进行电生理检查和射频消融治疗。结果特发性右心室室性心律失常（IRVA）516例,特发性左心室室性心律失常（ILVA）409例,IRVA多发生于女性,发病的平均年龄40岁,大多数表现为频发室早伴有反复单形室性心动过速,出现黑喙症状为14．3％;ILVA多发生于男性,发病的平均年龄33岁,多表现为持续性室速,出现黑矇症状为5．9％。IRVA有486例（94．2％）起源于右心室流出道,而在右心室流出道起源的室速／室早里,又以起源于间隔面的多见,占78％左右,起源于游离壁的占10％左右,其余的12％起源于二者之间的部位。射频消融多采用寻找心内膜最早激动点结合起搏标测来寻找合适的靶点。ILVA最多见的类型是左心室特发室速（ILVT）,有272例（66．5％）,ILVT主要起源于左后分支区域,也可以起源于左前分支区域和临近希氏束部位。主要用激动顺序标测结合浦肯野电位的方法确定消融靶点。IRVA的516例患者射频消融即刻成功率为89．3％。ILVA射频消融即刻成功率为93．7％。结论IVA患者虽然没有器质性心脏病,但是伴有多种临床症状,少部分病人甚至出现黑矇、晕厥,应积极行射频消融治疗,预防出现心室颤动危及生命。     

Electrocardiographic features of failed and recurrent right ventricular outflow tract catheter ablation of idiopathic ventricular arrhythmias

1 Introduction

Various ECG algorithms have been proposed to identify the origin of idiopathic outflow tract (OT)‐ventricular arrhythmia (VA). However, electrocardiographic features of failed and recurrent right ventricular outflow tract (RVOT) ablation of idiopathic OT‐VAs have not been clearly elucidated.

2 Methods and results

A total of 264 consecutive patients (mean age: 44.0 ± 13.0 years, 96 male) undergoing RVOT ablation for OT‐VAs with a transition ≥V₃, including 241 patients (91.6%) with initially successful procedures and 23 patients (8.4%) with failed ablation. Detailed clinical characteristics and ECG features were analyzed and compared between the two groups. VAs with failed RVOT ablation had larger peak deflection index (PDI), longer V₂ R wave duration (V₂Rd), smaller V₂ S wave amplitude, higher R/S ratio in V₂, higher V₃ R wave amplitude, and larger V₂ transition ratio than those with successful ablation. Multivariate analysis demonstrated that PDI, V₂Rd, V₂ transition ratio, and pacemapping score acquired during mapping independently predicted failed ablation (P  =  0.01, P  =  0.01, P  =  0.01, and P < 0.001, respectively). In 31 recurrent cases (12.8%) after initially successful ablation, multivariate Cox regression analysis showed that only the earliest activation time acquired during mapping predicted the recurrences after successful ablation (P  =  0.001). The recurrent cases displayed different ECG features comparing with those with failed ablation.

3 Conclusion

The electrocardiographic features of failed RVOT ablation of idiopathic OT‐VAs with a transition ≥V₃ were characterized by PDI, V₂Rd, V₂ transition ratio, and pacemapping score acquired during mapping, unlike the recurrent RVOT ablation.     

Use of the Impella™ Microaxial Blood Pump for Ablation of Hemodynamically Unstable Ventricular Tachycardia

Impella? for VT Ablation. Ablation for ventricular tachycardia remains a challenge with suboptimal procedural success rates. One of the major causes of difficulty is precipitous hypotension when ventricular tachycardia is induced precluding even rapid mapping of the arrhythmia. We report the successful use of the Impella? microcirculatory axial blood flow pump in 3 patients with hemodynamically unstable ventricular tachycardia that allowed successful completion of the procedure. In these 3 patients, there was no evidence of Impella?‐related valvular disturbance, iatrogenic ventricular arrhythmias, or interference with mapping and ablation catheter movement. (J Cardiovasc Electrophysiol, Vol. 21, pp. 458‐4, April 2010)     

单导管射频消融治疗右心室流出道源性心律失常

目的探讨单导管射频消融治疗右心室流出道源性心律失常的疗效与安全性。方法选择107例右心室流出道源性室性心律失常患者,其中室性心动过速12例,室性期前收缩95例。单点穿刺股静脉后,将单根消融导管按需放置于右心室心尖部、流入道或流出道。行电生理检查、起搏与激动顺序标测和消融治疗。结果消融成功101例,成功率94．39％。有效靶点电图较体表心电图QRS波群起始点提早（36．1±5．8）ms。成功靶点位于右心室流出道游离壁27例、后间隔26例、前间隔48例。操作时间（55．2±26．2）min,X线曝光时间（9．9±53）min,放电时间（418．2±163．6）s,术中无并发症发生。术后随访3月～3．5年,复发3例。结论单导管射频消融治疗右心室流出道源性室性心律失常安全、有效,操作简便,且节省费用。     

Characteristics of Sinus Rhythm Electrograms at Sites of Ablation of Ventricular Tachycardia Relative to All Other Sites: A Noncontact Mapping Study of the Entire Left Ventricle

Noncontact Mappin g of VT During Sinus Rhythm. Introduction : Regions of the diseased ventricle that activate abnormally during sinus rhythm (SR) may be the areas of slow and disorganized conduction that form the diastolic pathway through which reentry may occur during ventricular tachycardia (VT).
Methods and Results : We examined features of electrograms recorded during SR that might indicate a site suitable for ablation of VT using a noncontact mapping system, which enables reconstruction of > 3,000 electrograms. Preablation SR electrogram characteristics at sites of successful radiofrequency ablation (RFA) were examined in 13 patients with 53 VTs. Timing of onset, lateness of activity, electrogram duration, and number of baseline crossing events of reconstructed electrograms at the sites of successful RFA were compared with the electrograms of latest onset, latest activity, longest duration, and most baseline crossing events of all ventricular sites. Onset of activation at sites of successful RFA were 26.9 ± 25.2 msec (mean ± SD) earlier than (and 2.9 ± 1.7 cm away from) the site of latest onset of SR activation. Electrogram duration at sites of successful RFA was 83%± 14.6% of (and 4.3 ± 1.8 cm away from) the longest electrogram. The baseline crossing events at sites of successful RFA were 53%± 22% of (and 4.9 ± 1.9 cm away from) the most fractionated electrogram. The latest activity at sites of successful RFA was 21.6 ± 24.8 msec earlier than (and 4.3 ± 1.6 cm away from) the site of latest activity.
Conclusion : Although the site of latest onset of endocardial activation during SR proved to be the most sensitive indicator, the characteristics of SR electrograms did not usefully predict successful ablation sites.