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)     

Supracristal Ventricular Septal Defect Complicated by Formation of an Aorto-Right Ventricular Outflow Tract Fistula: A Rare Cause of Biventricular Enlargement

Aorto-right ventricular outflow tract fistulas typically occur secondary to trauma, infective endocarditis, and sinus of Valsalva aneurysm rupture. We describe an unusual case of a spontaneous aorto-right ventricular outflow tract fistula in the absence of such findings, instead forming secondary to a complicating supracristal ventricular septal defect and leading to dilated cardiomyopathy.     

Tachycardia-Induced Right Ventricular Cardiomyopathy: Epicardial Radiofrequency Ablation of an Unusual and Unexpected Ventricular Tachycardia

A 38-year-old man without prior medical history was hospitalized for sustained monomorphic ventricular tachycardia (VT) left bundle branch block pattern with inferior QRS axis resistant to beta blockers. Right ventricular (RV) ejection fraction (EF) was 28%. Left ventricular EF was normal. Right and left endocardial ablation failed. Percutaneous epicardial radiofrequency application at the lateral mitral annulus was successful. The RVEF later normalized.
Some VTs originating from the left ventricular epicardium are potential mimickers of benign VTs originating from the ventricular outflow tract (right or left) or arrhythmogenic right ventricular cardiomyopathy VT and they may induce isolated RV dysfunction.     

特发性室性心动过速的射频消融

目的:对经射频消融术证实的特发性室性心动过速的病例进行总结分析,探讨室性心动过速的发病状况、心电图特点、消融靶点的确定及消融结果。方法:对68 例特发性室性心动过速的起源部位和体表心电图进行分析,所有患者在诱发出室性心动过速后进行射频消融治疗,观察特发性室性心动过速的射频消融成功率和复发率以及它们和消融靶点的关系。结果:本组特发性室性心动过速患者中右室室性心动过速较左室室性心动过速多见。右室特发性室性心动过速心电图表现为左束支传导阻滞,左室特发性室性心动过速心电图则多表现为右束支传导阻滞。消融靶点的确定右室特发性室性心动过速主要采用起搏标测法,左室特发性室性心动过速主要采用激动顺序标测法。右室流出道室速组在起搏标测时起搏ECG和VT时ECG的12导联QRS波完全相同处消融成功率较高。结论:室性心动过速发作时的体表心电图可初步估计特发性室性心动过速的起源部位,射频消融术治疗特发性室性心动过速成功率高,并发症少。     

Radiofrequency Catheter Ablation of Sustained Monomorphic Ventricular Tachycardia in Hypertrophic Cardiomyopathy

Monomorphic VT in HCM. Introduction : Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm.
Methods and Results : The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal internals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds.
Conclusion : Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.     

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.     

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.     

Ablation of Ventricular Tachycardia Associated with Tetralogy of Fallot: Demonstration of Bidirectional Block

Ablation of VT in Tetralogy of Fallot. Introduction : Ventricular tachycardia is commonly seen in patients following surgical repair for tetralogy of Fallot. The technique of ablation for this arrhythmia is not well defined.
Methods and Results : In two patients with ventricular tachycardia following surgical repair of tetralogy of Fallot, the traditional indicators for a site for ventricular tachycardia ablation did not yield cure. Based on careful mapping, the circuit was found to involve the isthmus between the outflow tract patch and the tricuspid annulus; linear radiofrequency lesions across this isthmus resulted in cure of ventricular tachycardia. Not only was the tachycardia no longer inducible, but bidirectional block at the line of ablation confirmed interruption of the reentrant circuit.
Conclusion : A linear radiofrequency lesion was effective in eliminating ventricular tachycardia in both patients. The demonstration of bidirectional block confirms a cure independent of inducibility of ventricular tachycardia.     

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.     

特发性左室流出道室性心律失常的心电图特点

探讨特发性左室流出道室性心律失常患者的心电图特点。对 7例特发性左室流出道室性早搏 (简称室早 )、室性心动过速 (简称室速 )患者进行心电图分析 ,并行心内电生理检查及射频消融治疗 ,同时对 10例预激综合征患者成功消融房室旁道后行主动脉瓣上及瓣下起搏 ,记录同步 12导联起搏心电图。对比分析两组病例体表心电图QRS波图形特点。结果 :7例左室流出道室早、室速患者经心内电生理检查证实 6例起源于冠状动脉窦内 ,1例起源于左室流出道主动脉瓣右瓣下方 ,所有患者经射频消融成功治疗室性心律失常。对照组 10例在主动脉瓣下起搏(其中 6例同时在主动脉瓣上起搏 )获得同步 12导联起搏心电图。两组病例体表心电图共同特点为 :QRS波额面电轴向下 ,Ⅱ、Ⅲ、aVF导联主波向上 ,QRS波在V2 或V3 前移行为Rs或R型。结论 :左室流出道为特发性室早、室速发生部位之一 ,体表心电图有其独特性 ,导管射频消融治疗安全有效。     

Remote magnetic navigation to map and ablate left coronary cusp ventricular tachycardia

Background: Premature ventricular contractions (PVCs) and ventricular tachycardia may arise from the coronary cusps. Navigation, mapping, and ablation in the coronary cusps can be challenging. Remote magnetic navigation may offer an alternative to conventional manually operated catheters.
Objective: We report a case of left coronary cusp ventricular tachycardia ablation using remote magnetic navigation.
Methods: Right ventricular outflow tract and coronary cusp mapping, and ablation of the left coronary cusp using a remote magnetic navigation and three-dimensional (3-D) mapping system was performed in a 28-year-old male with frequent, symptomatic PVCs and ventricular tachycardia.
Results: Successful ablation of left coronary cusp ventricular tachycardia was performed using remote magnetic navigation.
Conclusions: Remote magnetic navigation may be used to map and ablate PVCs and ventricular tachycardia originating from the coronary cusps.     

Hypertrophic Cardiomyopathy with Right Ventricular Outflow Tract and Left Ventricular Intracavitary Obstruction

Obstruction of the right ventricular outflow tract (RVOT) is a rare finding in hypertrophic cardiomyopathy (HCM) patients unlike left ventricular outflow tract (LVOT) obstruction. Although there are guidelines that aid in clinical decision making in patients with LVOT obstruction, there are none addressing RVOT obstruction. As RVOT obstruction may pose serious clinical implications similar to LVOT obstruction, appropriate medical and surgical management is very important. A unique phenotype of HCM with RVOT obstruction in conjunction with left ventricle (LV) intracavitary obstruction is discussed.     

Unipolar Mapping and Magnetic Resonance Imaging of "Idiopathic" Right Ventricular Outflow Tract Ectopy

Unipolar Mapping and MRI of Ventricular Ectopy. Radiofrequency catheter ablation of symptomatic ventricular ectopy guided by bipolar mapping was successfully accomplished at the right ventricular outflow tract in a patient who did not exhibit apparent structural heart disease. A "QS" morphology with a fast slope of the downstroke deflection at the successful ablation site was observed on the unipolar electrogram. Focal thinning of the lateral wall of the right ventricular outflow tract was shown in the magnetic resonance image, similar to that reported in patients with "idiopathic" right ventricular outflow tract 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.     

家兔右室流出道细胞双孔钾通道电流特性的分析研究

目的已知特发性室速主要起源于右室流出道(RVOT),由于技术上的困难,目前对特发性右室流出道室速(RVOT-VT)的离子通道机制研究很少,本实验意在探索右室心室肌(RV)和RVOT的双孔钾通道电流(IK2p)的特性及其在RVOT-VT发生机制中可能参与的作用。方法采用全细胞膜片钳技术记录右室和右室流出道心肌细胞的单细胞电流。结果 RVOT的稳态外向电流较右室的小。对稳态电流进一步研究发现,右室流出道和右室心肌细胞上均存在IK2p。右室流出道细胞的IK2p电流密度明显小于右室细胞。结论首次在电生理水平上,证实了家兔右室心肌细胞上存在IK2p,RVOT心肌细胞的IK2p电流密度小于RV心肌细胞,是构成右室流出道APD离散度增大及外向电流降低的基础,从而易出现EAD,进而促进RVOT-VT的发生。     

器质性心脏病室性心动过速的导管射频消融治疗

总结导管射频消融 (RFCA)治疗 5例器质性心脏病室性心动过速 (简称室速 )的体会。电生理检查与RFCA一次完成。激动或 (和 )起搏标测确定靶点后消融。结果 :1例致心律失常性右室心肌病室速在右室心底部标测到较体表心电图 (ECG)之QRS波群提前 34ms的起始碎裂电位 ,室速可被隐匿拖带。 1例肥厚型心肌病术中发作 4种形态室速 ,分别于右室游离壁 ,流出道后侧壁、间隔前下及间隔前上标测到较体表ECG的QRS波群提前 40ms以上的碎裂电位 ,分别以此为靶点消融成功。 1例陈旧性心肌梗死室速于左室游离壁标测到较体表QRS波群提前 46ms的局部碎裂电位 ,起搏标测 12导联QRS波群形态与室速时完全一致 ,以此靶点消融成功。 1例扩张型心肌病 ,诱发束支折返性室速 ,消融右束支。 4例均消融成功 ,随访 10个月至 7年无复发。 1例Fallot四联征矫正术后患者有右室流出道室速发作 ,术中未能诱发室速 ,在起搏标测下消融 ,1个月后复发。 5例患者共发作 10种形态室速 ,消融成功 9种 ,复发 1种。平均手术时间 144min ,X线曝光时间 6 5min。结论 :对器质性心脏病反复发作的持续性单形性室速 ,RFCA是可行的治疗方法     

The Use of Fontaine Leads in the Diagnosis of Arrhythmogenic Right Ventricular Dysplasia

We report a case of a 68‐year‐old man admitted to the emergency department with syncope preceded by rapid palpitations. His admission ECG demonstrated a sustained ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT). This report highlights the importance of distinguishing ventricular tachycardia caused by arrhythmogenic right ventricular dysplasia (ARVD) from the more benign idiopathic RVOT‐VT. Furthermore, we demonstrate the utility of the Fontaine leads placement in increasing the sensitivity for uncovering epsilon waves, a highly specific electrocardiographic feature that increases diagnostic accuracy in patients with ARVD.     

Left Ventricular Outflow Tract Ventricular Tachycardia Originating from the Noncoronary Cusp: Electrocardiographic and Electrophysiological Characterization and Radiofrequency Ablation

Noncoronary cusp (NCC) ventricular tachycardia is a rare form of monomorphic outflow tract tachycardia, and its electrocardiographic and electrophysiological characteristics have not been well described previously. The NCC should be considered for catheter ablation if attempts to eliminate ventricular tachyarrhythmia were unsuccessful in the other common anatomical sites of the left ventricular outflow tract.     

Unruptured Sinus of Valsalva Aneurysm with Right Ventricular Outflow Tract Obstruction and Supracristal Ventricular Septal Defect: A Rare Case

Unruptured right sinus of Valsalva aneurysm that causes severe obstruction of the right ventricular outflow tract is extremely rare. We describe the case of a 47-year-old woman who presented with exertional dyspnea. Upon investigation, we discovered an unruptured right sinus of Valsalva aneurysm with associated right ventricular outflow tract obstruction and a supracristal ventricular septal defect. To our knowledge, only 2 such cases have previously been reported in the medical literature.Although treatment of unruptured sinus of Valsalva aneurysm remains debatable, surgery should be considered for extremely large aneurysms or for progressive enlargement of the aneurysm on serial evaluation. Surgery was undertaken in our patient because there was clear evidence of right ventricular outflow tract obstruction, right-sided heart dilation, and associated exertional dyspnea.     

静脉注射美托洛尔对肥厚型心肌病左心室功能的影响

目的:应用频谱多普勒超声心动图技术,定量观测肥厚型梗阻性心肌病和肥厚型非梗阻性心肌病患者经静脉注射美托洛尔前后左心室功能和左心室流出道压力阶差的变化,并观察血流动力学的变化,探讨静脉注射美托洛尔对肥厚型心肌病左心室功能的影响。方法:应用PHILIPS-SONOS7500型彩色多普勒超声诊断仪,测量用药前和用药后10分钟肥厚型梗阻性心肌病组(n=33)和肥厚型非梗阻性心肌病组(n=26)患者左心室功能各指标,并监测用药过程中的血流动力学变化。结果:肥厚型梗阻性心肌病组患者用药后较用药前左心室舒张功能明显改善,左心室流出道(LVOT)明显增宽(P<0.05),左心室流出道压力阶差(LVOTPG)明显下降(P<0.05),EF值无明显变化(P>0.05);肥厚型非梗阻性心肌病组患者用药后较用药前上述各指标无明显变化(P>0.05)。两组的心率、收缩压、舒张压用药后较用药前均明显降低(P<0.05),有显著差异。结论:静脉注射美托洛尔能够快速改善肥厚型梗阻性心肌病组患者的左心室舒张功能,改善临床症状,明显减轻左心室流出道梗阻,降低压力阶差,明显降低两组的血压、心率,影响其血流动力学;而对肥厚型非梗阻性心肌病组患者无明显作用,对两组的收缩功能均无明显影响。