Cryocatheter ablation of right ventricular outflow tract tachycardia

INTRODUCTION: Cryocatheter techniques have been successfully applied to treat supraventricular tachycardia but there are no reports on their value in treating ventricular tachycardia (VT). We present our initial experience with cryocatheter ablation of right ventricular outflow tract (RVOT) tachycardia. METHODS AND RESULTS: Cryocatheter ablation was attempted in 14 patients (13 females, age 45.9 +/- 12.7 years) who were highly symptomatic due to frequent monomorphic ventricular extrasystole (VES) or nonsustained VT originating within the RVOT. A 9-Fr, 8-mm-tip cryocatheter was used for both mapping and ablation. Cryoablation was started after localizing the arrhythmic focus by pace and activation mapping. Ablation success, defined by complete disappearance of target VES/VT acutely and during a follow-up of 9.3 +/- 1.4 weeks, was achieved in 13 of 14 patients. Ablation was successful with local activation times of 35 +/- 4 ms, 5.8 +/- 3.3 applications, 18.8 +/- 7.5 minutes total cryo time, 9.4 +/- 4.2 minutes fluoroscopy time, and 66.9 +/- 26.1 minutes total procedure time, the latter two measures showing a reduction with number of patients treated. Three patients reported slight pain related to local pressure of the catheter on the RVOT wall. No pain was described related to delivery of cryothermal energy. CONCLUSIONS: Initial experience shows that focal VES/VT originating in the RVOT can be successfully treated using cryocatheter ablation. Acute and short term success rates, fluoroscopy times, and duration of procedure are comparable to conventional ablation techniques. A major advantage seems to be the virtual absence of ablation related pain.     

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.     

Catheter ablation of right ventricular outflow tract tachycardia: value of defining coronary anatomy

INTRODUCTION: Thermal damage to coronary arteries during catheter ablation has been previously reported. Coronary artery damage during LV outflow tract ventricular tachycardia is well recognized. However, the relationship of the coronary arteries to the RV outflow tract during catheter ablation has not been delineated. The purpose of this study was to define the relationship between the RV outflow tract and the coronary arteries utilizing arteriography, echocardiography, CT angiography, and gross anatomic pathology. METHODS: The relationship of the coronaries to the RV outflow tract was analyzed in three patients groups: Group 1: patients (n = 10) undergoing RV outflow tract ventricular tachycardia; Group 2: patients (n = 50) undergoing CT coronary angiography; Group 3: patients (n = 4) undergoing echocardiography during open heart surgery and intracardiac echocardiography (ICE) during catheter ablation of atrial fibrillation (n = 5). RESULTS: Group 1: The left main coronary artery was found to be 3.8 +/- 1.2 mm from the right ventricular outflow tract in patients undergoing ablation. Group 2: The minimum distance between the left main, left anterior descending, and right coronary artery to the RV outflow tract endocardial wall were 4.1 +/- 1.9 mm, 2.0 +/- 0.6 mm, and 4.3 +/- 1.9 mm (average +/- SD) respectively. Group 3: During open heart surgery using echocardiography, the minimum distance between the left main and the right coronary artery to the RV outflow tract were 3.4 +/- 0.35 mm and 2.0 +/- 0.1 mm, respectively. The distance between the let main coronary artery and the RVOT by ICE was 3.8 +/- 0.45 mm. CONCLUSIONS: The major coronary arteries lie in close proximity of the RVOT, and their anatomic course should be taken into consideration during ablation of ventricular tachycardias arising from the RV outflow tract.     

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.     

Electrocardiographic determinants of the polymorphic QRS morphology in idiopathic right ventricular outflow tract tachycardia

Coupling Intervals and Polymorphic QRS Morphologies . Introduction: Premature ventricular contractions (PVCs) arising from the right ventricular outflow tract (RVOT) can trigger polymorphic ventricular tachycardia (PVT) or ventricular fibrillation (VF) in patients with no structural heart disease. We aimed to clarify the ECG determinants of the polymorphic QRS morphology in idiopathic RVOT PVT/VF. Methods and Results: The ECG parameters were compared between 18 patients with idiopathic PVT/VF (PVT‐group) and 21 with monomorphic VT arising from the RVOT (MVT‐group). The coupling interval (CI) of the first VT beat was comparable between the 2 groups. However, the prematurity index (PI) of the first VT beat was smaller in the PVT‐group than in the MVT‐group (P < 0.001). Furthermore, the QT index, defined as the ratio of the CI to the QT interval of the preceding sinus complex, was also smaller for the PVT/VF in the PVT‐group than that for the VT in the MVT‐group (P < 0.01). In the PVT‐group, the CI of the first VT beat was comparable between that of VT and isolated PVCs, but the PI of the first VT beat was shorter for VT than isolated PVCs (P < 0.05). The PI was the only independent determinant of the polymorphic QRS morphology (odd ratio = 2.198; 95% confidence interval = 1.321–3.659; P = 0.002). Conclusion: The smaller PIs of the first VT beat may result in a polymorphic QRS morphology. (Cardiovasc Electrophysiol, Vol. 23, pp. 521‐526, May 2012)     

Catheter ablation of ventricular tachycardia in arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a progressive, genetically determined fibro-fatty infiltrative myocardial disease with an estimated prevalence in the general population to be 1:5,000 to 1:10,000. ARVD leads to electrical instability that may predispose to life-threatening ventricular arrhythmia, heart failure, and sudden death. We reviewed the pathological substrate for ventricular arrhythmias, ECG findings and treatment modalities in ARVD. Importantly, novel techniques such as electroanatomic and voltage mapping has greatly improved the identification of the scared substrate in the settings of ARVD and have improved safety and efficacy of VT ablation procedures associated with this entity.     

特发性左心室流出道心外膜侧室性心动过速

目的报道9例经电生理检查证实的特发性左心室流出道心外膜侧室性心动过速(室速)的体表心电图及电生理检查特点.方法男性5例,女性4例,年龄15～58岁,6例为运动诱发的持续性室速,3例为运动诱发的非持续性室速.结果室速时,9例体表心电图QRS波全部呈现右束支阻滞图形(8例胸前导联V1-V6呈现高R波),Ⅱ、Ⅲ、aVF导联为高R波,Ⅰ、aVL导联为QS波.电生理检查,右心室和左心室心内膜标测未发现最早心室激动点,在较早心室心内膜激动处的心内电图多呈现起始部低幅电位,提示远场电位.心室内起搏标测未发现与室速体表心电图12导联QRS波形态相同的起搏点.8例通过心脏静脉系统标测发现最早的心室激动点[体表心电图最早QRS波前15～50ms,平均(32±12)ms]和完全或近乎完全的起搏标测位于心大静脉的远端1例、心前间隔静脉的近端7例.1例患者在左心室流出道消融成功,1例患者在心大静脉远端血管内消融成功.其他患者在右心室和/或左心室内消融失败.结论心脏静脉标测可以鉴别出特发性左心室流出道心外膜侧室速.     

Acute coronary artery occlusion and ischemia-related ventricular tachycardia during catheter ablation in the right ventricular outflow tract

Coronary artery injury is a rare complication of catheter ablation in the right ventricular outflow tract (RVOT). Furthermore, acute myocardial ischemia usually causes polymorphic ventricular tachycardia (VT) or ventricular fibrillation. We herein describe a case in which catheter ablation for VT originating from the RVOT provoked ischemia-related VTs due to acute occlusion of the left anterior descending artery.     

Spontaneous right ventricular outflow tract tachycardia in a patient with Brugada syndrome

We report the case of a 28-year-old man with no structural heart disease, who exhibited clearly augmented ST segment elevation in the right precordial leads, followed by induction of spontaneous right ventricular outflow tract tachycardia with intravenous administration of Class IA antiarrhythmic drugs. The electrophysiologic mechanism of this tachycardia was thought to be triggered activity due to delayed afterdepolarizations. Due to the existence of substrates that were similar to Brugada syndrome combined with right ventricular outflow tract tachycardia, this case may represent a subtype of Brugada syndrome.     

Hoffmayer心电图积分识别ARVC室早／室速

目的探讨应用Hoffmayer心电图积分鉴别致心律失常性右室心肌病（arrhvthmogenic right ventricular cardiomyopathy,ARVC）和特发f生右室流出道室早／室速的临床意义。方法收集2009年9月至2013年5月就诊于北京大学人民医院患者中,心电图表现为右室流出道起源室早／室速患者57例。其中明确诊断为ARVC患者4例,经电生理检查及射频消融治疗成功的特发性右室流出道室早／室速患者53例。由两位电生理医生在不知道确切诊断的情况下,依据Hoffmayer心电图积分对上述患者的心电图进行分析,计算总积分≥5分,各单项积分诊断ARVC伴发的室早／室速的敏感度、特异度、阳性预测值、阴性预测值及诊断符合率。结果Hoffmayer心电图积分≥5分诊断ARVC伴发室早／室速的敏感度75％,特异度96．23％,阳性预测值60％,阴性预测值98％、诊断符合率94．7％。结论Hoffmayer积分≥5可有效鉴别右室流出道室早／室速是ARVC伴发的还是特发性的。应用此项积分具有简单、快速、敏感度及特异度均较高的优点,具较高的临床应用价值。     

采用心内非接触式标测的右心室流出道室性心动过速的射频消融

目的 右心室流出道(right ventricular outflow tract,RVOT)的解剖结构使得对该部位的室性心动过速(ventricular tachyeardia,VT,室速)标测定位的难度较大,远期成功率也较低,为此,采用心内非接触式标测指导导管消融。方法 20例患者(男性12例,女性8例),年龄14～59(35.1±12.3)岁。其中6例有晕厥或黑矇史,7例既往曾接受射频消融未获成功。全部患者均在RVOT内放置EnSite3000标测导管,在窦性心律下进行疤痕标测和心动过速时进行最早激动标测,并根据标测结果使用EnSite 3000导管的导航功能指导消融定位。消融前并进行起搏标测。结果 20例患者共诱发出22种RVOT室速,其中3例还伴其它起源的室性早搏(室早)。疤痕标测提示,13例患者有电学意义上的疤痕区域,且有11例室速起源于该疤痕区域。25个室速或室早起源点中1例起源于近肺动脉瓣口部,10个位于间隔侧,其余均偏游离壁,其中7个偏RVOT后壁中、下部,4个偏前壁中、下部,3个位于游离壁侧;病变基质的直径为6～42 mm,平均(16.8±9.2)mm。非接触式标测所确定的最早激动处电位平均领先体表20～62(41.0±13.8)ms;与自发的室性心动过速相比,起搏标测下14例的12个导联QRS形态完全一致,11/12个导联一致的为10例,1例有10/12导联一致。全部室速和室早均消融成功。在标测确定的     

Catheter ablation of stable and unstable ventricular tachycardias in patients with arrhythmogenic right ventricular dysplasia

INTRODUCTION: A reentrant circuit within an area of abnormal myocardium is suspected as the origin of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular dysplasia (ARVD). OBJECTIVES: To examine the relationship between the reentrant circuits of VT and the abnormal electrograms in ARVD, and to assess the feasibility of a block line formation in the reentrant circuit isthmus utilizing electroanatomical mapping system (CARTO) guidance. METHODS AND RESULTS: An electrophysiological study and catheter ablation (CA) were performed in 17 ARVD patients (13 men, 47 +/- 17 year) using CARTO. Endocardial mapping during sinus rhythm demonstrated electrogram abnormalities extended from the tricuspid annulus (TA) or the right ventricular outflow tract in 16 of 17 patients. In 13 hemodynamically stable VTs, the reentrant circuits and critical slow conduction sites for the CA were investigated during VTs. The entire macro-reentrant pathway was identified in 6/13 stable VTs (figure-of-8 in 4, single loop in 2). In the remaining seven VTs, a focal activation pattern was found in four and an unidentifiable pattern in three. CA successfully abolished all the macro-reentrant and focal tachycardias, however, not effective in three unidentifiable VTs. In the 13 cases with unstable VT, the linear conduction block zone was produced between the sites with abnormal electrograms and the TA. Ultimately, 23/26 VTs (88%) became noninducible after the CA. During follow-up (26 +/- 15 months), 13/17 patients remained free from any VT episodes. CONCLUSIONS: CARTO is useful for characterizing the anatomical and electrophysiological substrates, and for identifying the optimal ablation sites for VT associated with ARVD.     

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.     

射频导管消融特发性左心室流出道室性心动过速

目的 探讨特发性左心室流出道室性心动过速(室速)心电图特点及射频导管消融结果。方法 对5例未发现器质性心脏病的左心室流出道室速患者行12导联心电图、动态心电图、心内电生理检查及射频导管消融治疗。结果5例患者心电图Ⅱ、Ⅲ、aVF导联呈R波；Ⅰ导联呈rs或QS波，振幅大于0．5mV；V1导联呈rs或RS波，胸前导联R波移行发生于V2～V3；aVR和aVL导联呈QS波，3例患者的消融靶点在左冠状窦口内，2例位于主动脉瓣下，随访6个月，无1例复发。结论 左心室流出道室速有特殊心电图表现，射频导管消融是首选的治疗措施。     

Metastatic cardiac malignant fibrous histiocytoma presenting as right ventricular outflow tract obstruction.

An unusual case of metastatic disease of the right ventricle is described in a 74-year-old woman who had presented with a malignant fibrous histiocytoma of the right thigh previously treated with surgery and radiotherapy. Two years later she presented with signs and symptoms of tricuspid regurgitation and right ventricular outflow tract obstruction. The diagnosis of right ventricular tumor was made by echocardiographic and angiographic studies and confirmed on postmortem examination.     

Remote magnetic navigation for mapping and ablating right ventricular outflow tract tachycardia

BACKGROUND: Navigation, mapping, and ablation in the right ventricular outflow tract (RVOT) can be difficult. Catheter navigation using external magnetic fields may allow more accurate mapping and ablation. OBJECTIVES: The purpose of this study was to assess the feasibility of RVOT tachycardia ablation using remote magnetic navigation. METHODS: Mapping and ablation were performed in eight patients with outflow tract ventricular arrhythmias. Tachycardia mapping was undertaken with a 64-polar basket catheter, followed by remote activation and pace-mapping using a magnetically enabled catheter. The area of interest was localized on the basket catheter in seven patients in whom an RVOT arrhythmia was identified. Remote navigation of the magnetic catheter to this area was followed by pace-mapping. Ablation was performed at the site of perfect pace-mapping, with earliest activation if possible. RESULTS: Acute success was achieved in all patients (median four applications). Median procedural time was 144 minutes, with 13.4 minutes of patient fluoroscopy time and 3.8 minutes of physician fluoroscopy time. No complications occurred. One recurrence occurred during follow-up (mean 366 days). CONCLUSION: RVOT tachycardias can be mapped and ablated using remote magnetic navigation, initially guided by a basket catheter. Precise activation and pace-mapping are possible. Remote magnetic navigation permitted low fluoroscopy exposure for the physician. Long-term results are promising.     

Arrhythmogenic right ventricular dysplasia presenting as acute coronary syndrome: a case report.

Arrhythmogenic right ventricular dysplasia (ARVD) is underdiagnosed cardiomyopathy which commonly presents in young adults with ventricular tachycardia or sudden death. We report a case of ARVD presenting with features of acute coronary syndrome. The suspicion of ARVD came only when echocardiogram revealed abnormal shape and wall motion of right ventricle, which was later confirmed by right ventricular angiogram. The diagnosis of ARVD was discussed and the literature reviewed.