An Unusual Case Of Right Ventricular Outflow Tract Tachycardia

In this report, we describe an unusual case of right ventricular outflow tract (RVOT) tachycardia with episodes of repetitive monomorphic ventricular tachycardia (VT), paroxysmal sustained VT and incessant monomorphic VT of the same morphology. Diltiazem, adenosine, or metoprolol failed to interrupt these arrhythmias. However, administration of intravenous propafenone completely eliminated all ventricular ectopic activity. Electrophysiologic study performed off propafenone showed that the ventricular ectopic activity originated from a single locus at the anterior wall of the RVOT. Two radiofrequency applications at this site resulted in complete elimination of ventricular ectopic activity.     

Idiopathic Right Ventricular Tract Outflow Tachycardia Induced by High‐Frequency Stimulation

Idiopathic Right Ventricular Tract Outflow Tachycardia Induced by High‐Frequency Stimulation. Ventricular tachycardia arising from the right ventricular outflow tract is one of the common forms of idiopathic ventricular tachycardia. One of the major challenges in mapping and ablation of idiopathic right ventricular outflow tract ventricular tachycardia is noninducibility. Direct stimulation of sympathetic nerves innervating the right ventricular outflow may provide an alternative approach to induce arrhythmia. We report a case of idiopathic right ventricular outflow tract tachycardia in whom tachycardia was noninducible by aggressive conventional stimulation protocols, which was induced by high‐frequency stimulation of proximal pulmonary artery and was successfully ablated. (J Cardiovasc Electrophysiol, Vol. 24, pp. 221‐223, February 2013)     

Tachycardia-Induced Cardiomyopathy Secondary to Right Ventricular Outflow Tract Ventricular Tachycardia: Improvement of Left Ventricular Systolic Function After Radiofrequency Catheter Ablation of the Arrhythmia

Cardiomyopathy Secondary to RVOT VT. Introduction : Several reports describe development of cardiomyopathics secondary to supraventricular tachycardia. Few reports have described cardiomyopathies secondary to ventricular tachycardia.
Methods and Results : We describe a patient who presented with dilated cardiomyopathy and repetitive nonsustained monomorphic ventricular tachycardia. Cardiac cathcterization showed hemodynamically insignificant coronary artery disease. Radiofrequency ablation of a right ventricular outflow tract ventricular tachycardia resulted in improvement of the left ventricular systolic function and resolution of heart failure symptoms.
Conclusions : This report suggests that right ventricular outflow tract ventricular tachycardia may cause reversible tachycardia-induced cardiomyopathy.     

非接触心内膜激动标测系统指导消融右室流出道室性心动过速

探讨非接触心内膜激动标测系统(NMS)指导消融右室流出道室性心动过速 (RVOT VT)的临床使用价值。选择 12例RVOT VT患者在NMS EnSite 3000TM指导下进行电生理标测和消融治疗, 经股静脉将 9F64极球囊电极(Array)和普通 7F消融电极送至RVOT采集信号,计算机将采集到的 3 360个点的实时心内膜电图通过逆运算法处理后显示分析RVOT三维立体图上彩色等电势图,确定心动过速时心内膜最早激动点。在脱离X线时,由导航和定位系统实时跟踪导管位置变化,并实施靶点消融。9例能诱发出持续性或非持续性VT, 3例仅能诱发RVOT早搏。与以往传统方法消融的 19例结果相比较,心内膜最早激动时间 (EEAT)较体表心电图QRS波的起点提前(29. 4±12. 3msvs18. 7±8. 1ms,P<0. 01),放电部位减少 ( 5. 7±3. 4vs8. 2±3. 1,P<0. 05 )个,手术时间延长(246. 9±53. 0minvs190. 2±74. 6min,P<0. 05);X线曝光时间(44. 3±17. 5minvs57. 5±20. 1min)、即刻成功率(100% vs84. 2% )、6个月随访成功率(100% vs73. 7% ),没有显著性差异,P均>0. 05。结论:NMS指导消融RV OT VT安全可靠,靶点定位准确,且在提高远期成功率方面有优于传统标测方法的趋势。     

Ablation of Idiopathic Right Ventricular Outflow Tract Tachycardia: Current Perspectives

Ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) in the absence of overt structural heart disease is a common entity. Exclusion of occult structural disease such as arrhythmogenic right ventricular cardiomyopathy is critical as this diagnosis impacts both ablation outcomes and long-term prognosis. VT is most commonly due to triggered activity. Induction of the target arrhythmia in the laboratory is often problematic, and is frequently facilitated by catecholamine infusion. Recent data indicate that high-density three-dimensional activation mapping facilitates identification of target sites for ablation, and that the spatial resolution of pacemapping may be more limited than previously recognized. A standard 12-lead electrocardiogram is useful in providing an initial approximation of the site of origin within the outflow tract, and may contain subtle clues to potentially confounding foci on the left ventricular endocardial or epicardial surface. When sufficient arrhythmia is present to permit mapping, successful ablation can be expected in 90–95% of patients, with a recurrence risk of approximately 5%. In experienced centers, major complications are ≤1% and outcomes should approach those obtained for the common forms of supraventricular tachycardia.     

Radiofrequency Catheter Ablation of Left Ventricular Outflow Tract Tachycardia:

Left Ventricular Outflow Tract Tachycardia. Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. We report two patients whose QRS configuration during VT commonly showed an inferior axis and monophasic R waves in all the precordial leads. The mechanism of these VTs appeared to be triggered activity. From mapping and ablation, the origin of these VTs was determined to be in the most posterior LVOT, corresponding to the aortomitral continuity (left fibrous trigone).     

Clinical and Electrophysiological Difference Between Idiopathic Right Ventricular Outflow Tract Arrhythmias and Pulmonary Artery Arrhythmias

Characteristics of Pulmonary Artery Arrhythmias. Introduction: The precise incidence and characteristics of ventricular arrhythmias originating from the pulmonary artery have not been fully described. The purpose of this prospective study was to clarify these points. Methods: Thirty‐three consecutive patients with an idiopathic left bundle branch block and inferior‐axis deviation type ventricular arrhythmia were included. All patients underwent detailed electroanatomical mapping (CARTO, Biosense‐Webster, Diamond Bar, CA, USA) during sinus rhythm prior to the catheter ablation. The precise location of the catheter tip at the successful ablation site was confirmed by both electroanatomical mapping and contrast radiography. The clinical and electrophysiological data were compared between the right ventricular outflow tract (RVOT) arrhythmia patients (RVOT group) and PA arrhythmia patients (PA group). Results: Eight patients (8/33 patients: 24.2%) had their ventricular arrhythmias successfully ablated within the PA. The local bipolar electrogram at the successful ablation sites in the PA group exhibited a significantly greater duration (P < 0.05) and lower amplitude (P < 0.05) than did those in the RVOT group (n = 19). In the PA group, all patients exhibited a multicomponent electrograms composed of a spiky potential and a dull potential, which might have consisted of near‐field PA activation and a far‐field ventricular activation, respectively, at the successful ablation site. Direct ablation to the spiky electrogram was able to eliminate the arrhythmias in all the PA group patients. Conclusions: PA arrhythmias may be more common than previously recognized. Careful mapping and interpretation of low amplitude and multicomponent electrograms are important for recognizing ventricular arrhythmias originating from the PA. (J Cardiovasc Electrophysiol, Vol. 21, pp. 163‐169, February 2010)     

Human Model Simulating Right Ventricular Outflow Tract Tachycardia by High-Frequency Stimulation in the Left Pulmonary Artery: Autonomics and Idiopathic Ventricular Arrhythmias

Introduction: Frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia (VT) in patients with structurally normal heart usually arise from the right ventricular outflow tract (RVOT). An animal model simulating RVOT tachycardia by high-frequency stimulation (HFS) of the sympathetic input to the proximal pulmonary artery (PA) has been previously described. The aim of this study was to similarly induce RVOT tachycardia in humans.
Methods: In 9 patients with no history of ventricular arrhythmias, a circumferential catheter was placed in the left, main, and proximal PA to contact the endovascular circumference of the PA. A 50-ms train of HFS (200 Hz/0.3 ms pulse duration), coupled to atrial pacing, was applied at each bipolar pair of the circumferential catheter. The coupling interval was adjusted so that the 50-ms train occurred during the ventricular refractory period.
Results: In 6 out of 9 patients, HFS in the left PA during dobutamine infusion induced monomorphic PVCs and/or VT with left bundle branch block (LBBB) morphology and inferior axis at an average stimulation level of 12.5 ± 2.7 V. HFS in the main PA and in the proximal PA did not induce any ventricular arrhythmias with the highest energy of 15 V in baseline state and during dobutamine infusion. HFS in the left PA was associated with hiccough in all patients.
Conclusion: Stimulation of the sympathetic input to the left PA during dobutamine infusion induces PVCs and/or VT exhibiting LBBB-morphology and inferior axis, closely simulating clinical RVOT tachycardia in humans.     

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)     

特发性束支折返性室性心动过速的临床特点(附二例报道)

通过对两例特发性束支折返性室性心动过速 (BBR VT)的临床、心电图及电生理特性进行分析 ,提出该类病人的临床特点。两例病人均无器质性心脏病的证据。例 1男性 ,VT发作最长持续达 2 7h ,体表心电图呈近似心室扑动的图形 ,心内电生理检查证实为类左束支阻滞图形 ,QRS波宽 2 6 0ms。平时体表心电图QRS波正常 ,心内电图提示HV间期延长 ,VT可稳定诱发和终止 ,存在V3 现象 ,右束支消融成功。例 2女性 ,VT发作病史 7年 ,呈无休止性VT发作 ,平时体表心电图为完全性右束支传导阻滞伴左前分支阻滞图形 ,VT可稳定诱发和终止 ,发作时其QRS波宽为 14 0ms ,呈类完全性右束支传导阻滞伴左前分支阻滞图形 ,V波前有稳定的H波 ,消融左后分支后可导致Ⅲ度房室阻滞而终止VT。结论 :束支折返性VT可见于无器质性心脏病病人 ,有独特的电生理特性 ;是一种特殊类型的特发性VT     

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.     

右室流出道起搏现状

右室心尖部作为传统的永久心脏起搏器植入位点,主要是因为电极容易放置及电极脱位率低。但是心尖部起搏属非生理性起搏,它使心室除极和机械收缩发生异常,从而导致长期的血流动力学紊乱(心室收缩和舒张异常)和组织结构的改变。随着近年主动固定的螺旋电极及螺旋电极操作手柄的问世,使右室流出道起搏成为可能。大量动物实验和临床研究提示右室流出道靠近房室结、希氏束部位,在此部位起搏心室激动和收缩顺序趋于正常,从而能明显的改善血流动力学指标。目前右室流出道起搏尚处于临床实验阶段,且关于右室流出道解剖位点的确定,适宜患者群的筛选标准、监测和评价指标的选择尚无统一的标准。其长期效果及能否改善患者预后等还有待更深入的研究。现就目前国内外关于右室流出道起搏的研究现状综述如下。     

环形标测电极指导下射频导管消融右心室流出道室性心动过速

探讨环形电极对右室流出道室性心动过速(RVOTVT)的标测指导作用及射频消融方法。6例特发性RVOTVT患者,男4例、女2例,年龄35.0±6.3(18～42)岁。行常规电生理检查,应用环形电极标测右室流出道,以最早激动点结合窦性心律下起搏标测确定靶点。结果:4例起源于右室流出道间隔前部,1例起源于间隔后部,1例起源于游离壁,6例均成功进行了射频消融,成功率100%。平均手术时间78±22min。结论:环形标测电极可以指导快速寻找室性心动过速起源点,缩短标测及消融时间。     

小儿右室流出道起搏

对于一些需要安装永久起搏器的患者来讲,由于易于固定,起搏阈值低等优点,右心室起搏常将起搏电极置于心尖部,但长期随访发现,心尖部起搏可改变心室激动顺序,导致心室收缩不同步,造成二尖瓣反流、心房颤动和心功能不全。研究发现右室流出道起搏对左室功能的保护较右室心尖部起搏有利,由于右室流出道起搏靠近His束,电活动近似正常生理状态,可使左右心室电-机械活动更协调,从而抑制心室重构并保护心功能,因此,右室流出道起搏是替代右室心尖部起搏的较好选择。     

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.     

Catheter Ablation of the Left Ventricular Outflow Tract Tachycardia from the Left Atrium

RF ablation of idiopathic left ventricular outflow tract ventricular tachycardia (LOT-VT) may imply in significant risk of damaging the proximal left main if RF pulses are being delivered from the left sinus of Valsalva or from inside an epicardial coronary vein. This report describes a new approach to control LOT-VT by means of RF catheter ablation.     

Therapy of "Idiopathic" Ventricular Tachycardia

"Idiopathic" Ventricular Tachycardia. Idiopathic ventricular tachycardias occur in "normal" hearts and are generally benign arrhythmias. They can arise from either the left or right ventricle, and the origin is usually predictable from the surface ECG. These arrhythmias are produced by diverse mechanisms. When treatment is indicated, empiric pharmacotherapy can he successful. However, if drugs are not tolerated or tail, radiofrequency (RF) ablation may he indicated. During electrophysiologic study, arrhythmia mechanism tan he determined, and pace and activation mapping can he used to localize the site of ventricular tachycardia origin to direct application of RF lesions. RF ablative therapy has been associated with high success rates.     

左束支阻滞型特发性室性心动过速的心电图特征对射频消融成功的影响初探

对心电图呈左束支阻滞型的特发性室性心动过速 (简称室速 )的临床特点和心电图进行分析 ,以了解哪些因素可以预测此类患者从右室流出道行射频消融的成功率。对 2 6例特发性室速的患者进行电生理检查和射频消融手术 ,全部患者室速时的心电图呈左束支阻滞。结果 :2 6例中 ,2 2例于右室流出道进行了成功消融 ,成功和未成功消融的患者临床特征和电生理无明显区别 ,成功消融的患者中胸前V1 导联心电图呈rS型 (1 2例 )和QS型 (1 0例 ) ,而 4例未成功者 ,V1 导联均呈rS型 ,其中 2例经主动脉于左冠状窦消融成功。在成功与未成功消融患者中 ,V1 导联有无R波无明显区别 ,但V1 导联无R波预示室速可以从右室流出道成功消融 ,成功消融的室速患者胸前导联的平均移行区在V4导联 ,而未成功患者胸前导联的移行区在V3 或V2 导联。结论 :某些心电图呈左束支阻滞 ,且额面电轴正常或右偏的特发性室速患者不能成功从右室流出道消融 ,V1 导联有r波且移行区在V3 导联或之前者提示此类心电图特征的室速可能非起源于右室流出道 ,部分可能起源于左室流出道