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)     

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.     

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.     

Ventricular tachycardias mimicking those arising from the right ventricular outflow tract

INTRODUCTION: Ablation of ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) has proven highly successful, yet VTs with similar ECG features may originate outside the RVOT. METHODS AND RESULTS: We reviewed the clinical, echocardiographic, and ECG findings of 29 consecutive patients referred for ablation of monomorphic VT having a left bundle branch block pattern in lead V1 and tall monophasic R waves inferiorly. Nineteen patients (group A) had VTs ablated from the RVOT, and 10 patients (group B) had VTs that could not be ablated from the RVOT. The QRS morphology during VT or frequent ventricular premature complexes was the only variable that distinguished the two groups. During the target arrhythmia, ECGs of group B patients displayed earlier precordial transition zones (median V3 vs V5; P < 0.001), more rightward axes (90 +/- 4 vs 83 +/- 5; P = 0.002), taller R waves inferiorly (aVF: 1.9 +/- 1.0 vs 2.4 +/- 0.5; P = 0.020) and small R waves in lead V1 (10/10 vs 9/19; P = 0.011). Radiofrequency catheter ablation from the RVOT failed to eliminate VT in any group B patient, but ablation from the left ventricular outflow tract (LVOT) eliminated VT in 2 of 6 patients in whom left ventricular ablation was attempted. CONCLUSION: The absence of an R wave in lead V1 and a late precordial transition zone suggest an RVOT origin of VT, whereas an early precordial transition zone characterizes VTs that mimic an RVOT origin. The latter VTs occasionally can be ablated from the LVOT. Recognition of these ECG features may help the physician advise patients and direct one's approach to ablation.     

Substrate in the interventricular septum for left ventricular and right ventricular outflow tract tachycardia: ablation from the right side of the septum

Simultaneous epicardial and endocardial mapping demonstrated that in a substantial number of ventricular tachycardias (VTs) endocardial, intramural, and epicardial structures are involved in the substrate of the reentrant circuits. Both right and left ventricular breakthrough has also been described during VT originating in the interventricular septum. We report the case of a patient with a nonischemic left ventricular aneurysm presenting with a left ventricular outflow tract (LVOT) tachycardia and a right ventricular outflow tract (RVOT) tachycardia. Mapping from the anterior interventricular vein and the endocardium of the RVOT revealed mid-diastolic potentials at the epicardium of the LVOT and the endocardium of RVOT, where the criteria of central isthmus sites could be demonstrated. Ablation targeting an isolated late potential during sinus rhythm in RVOT eliminated both the LVOT tachycardia and the RVOT tachycardia. In this patient with a nonischemic left ventricular aneurysm, the substrate of a LVOT tachycardia and RVOT tachycardia is described, and successful catheter ablation of the right and left ventricular tachycardia from the septal wall of RVOT is reported.     

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。     

Electrocardiographic predictors of failure and recurrence in patients with idiopathic right ventricular outflow tract tachycardia and ectopy who underwent radiofrequency catheter ablation

This study reports new electrocardiographic (ECG) predictors of radiofrequency catheter ablation failure and recurrence in idiopathic right ventricular outflow tract (RVOT) ventricular tachycardia (VT) or ectopy based on 91 consecutive patients. Procedural success and failure rates were 85% (77/91) and 15% (14/91), respectively. Twenty three percent (18/77) had recurrence during the follow-up period of 1 to 120 months (mean 56 +/- 31 months). Baseline RVOT VT/ectopy on 12-lead ECG taken prior to ablation from 91 patients were retrospectively analyzed. Ablation performed with RVOT ectopy (isolated ectopies, bigeminy, trigeminy, or couplets) as template arrhythmia was more likely to fail (30% vs. 8%, P =.02) as opposed to RVOT VT (sustained or nonsustained). VT/ectopy-QRS morphology variation was more observed in failed ablations (36% vs. 7%, P =.001). Significantly wider mean VT/ectopy QRS in leads I, II, AVR, V2, V3, V5, and V6 were noted in failed ablation group. Mean R wave amplitude reached statistical significance only in lead II (22.0 +/- 5.1 mV for failed vs. 17.8 +/- 5.2 mV for successful outcomes; P =.009). QRS morphologic variation (47% vs. 16%; P =.009) was the only statistically significant ECG to be more common in patients with arrhythmia recurrence. In conclusion, ablation with ectopy over VT as template arrhythmia, presence of QRS morphologic variation, wider mean QRS width, and taller mean R-wave amplitude in lead II were identified ECG predictors of failed RVOT VT/Ectopy ablation. The only ECG predictor of recurrence was the presence of RVOT VT or ectopy QRS morphologic variation.     

Noncontact mapping to guide ablation of right ventricular outflow tract tachycardia

OBJEWCTIVES: The aim of this study was to determine whether noncontact mapping is feasible in the right ventricle and assess its utility in guiding ablation of difficult-to-treat right ventricular outflow tract (RVOT) ventricular tachycardia (VT). BACKGROUND: In patients without inducible arrhythmia, RVOT VT may be difficult to ablate. Noncontact mapping permits ablation guided by a single tachycardia complex, which may facilitate ablation of difficult cases. However, the mapping system may be geometry-dependent, and it has not been validated in the unique geometry of the RVOT. METHODS: Ten patients with left bundle inferior axis VT, no history of myocardial infarction and normal left ventricular function underwent noncontact guided ablation; seven had failed previous ablation and three had received a defibrillator. All noncontact maps were analyzed by a blinded reviewer to determine whether the arrhythmia focus was epicardial and to predict on the basis of the map whether arrhythmia would recur. RESULTS: The procedure was acutely successful in 9 of 10 patients. During a mean follow-up of 11 months, 7 of 9 patients remained arrhythmia-free. Both patients in whom the blinded reviewer predicted failure had arrhythmia recurrence: one due to epicardial origin with multiple endocardial exit sites and one due to discordance between site of lesion placement and earliest activation on noncontact map. CONCLUSIONS: Mechanisms of ablation failure in RVOT VT include absence of sustained arrhythmia, difficulty with substrate localization and epicardial origin of arrhythmia. In this study, noncontact mapping was safely and effectively used to guide ablation of patients with difficult-to-treat RVOT VT.     

Mechanistic subtypes of focal right ventricular tachycardia

Idiopathic sustained focal right ventricular tachycardia (VT) is most frequently due to outflow tract (OT) tachycardia. This arrhythmia is recognized by its characteristic ECG pattern and sensitivity to adenosine. However, there are other forms of idiopathic, focal sustained VT that originate from the right ventricle (RV), which are less well appreciated and easily overlooked. This review will identify the characteristic features and electrophysiologic properties of these forms of RV VT, including those originating from the tricuspid annulus, right ventricular papillary muscles, and moderator band as well as variants of classic RVOT tachycardia and those due to microreentry in the presence of preclinical disease. Recognition of these subtypes of focal RV tachycardia should facilitate targeted therapy.     

Left ventricular outflow tract tachycardia originating from the right coronary cusp: identification of location of origin by endocardial noncontact activation mapping from the right ventricular outflow tract

Idiopathic left ventricular outflow tract (LVOT) tachycardia has been shown to originate from a supravalvular site in some patients. Considerable attention recently has focused on identifying this variant of LVOT tachycardia on 12-lead ECG. We report the case of 15-year-old boy in whom a noncontact three-dimensional mapping electrode deployed in the right ventricular outflow tract (RVOT) assisted in identifying a supravalvular LVOT tachycardia. Observation of two early breakthrough sites in the RVOT and right ventricular septum suggested a right aortic cusp origin of the tachycardia. Pace mapping in the right aortic cusp identified a successful ablation site.     

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.     

特发性室性心动过速及室性期前收缩的射频消融治疗

目的探讨射频导管消融(radiofrequency catheter ablation,RFCA)治疗特发性室性心动过速(idiopathic ventricular tachycardia,IVT)和室性期前收缩(premature ventricualr contraction,PVC)可行性、必要性和疗效。方法回顾性分析16例IVT、PVC患者采用激动顺序标测和起搏标测法确定室性心动过速(ventricular tachycardia,VT)、PVC的起源部位并行RFCA治疗的资料。结果 3例IVT中2例起源于左室间隔部左后分支的蒲肯野系统,1例起源于右心室流出道(right ventricular outflow tract,RVOT)游离壁,同时合并另一种游离壁起源的PVC,3例消融均成功,1例复发。13例PVC中7例起源RVOT间隔部,3例起源于RVOT游离壁,1例同时存在两种形态PVC(分别起源于ROVT间隔部和游离壁),2例起源于左心室流出道,13例消融成功,1例复发。结论 RFCA治疗IVT及特定部位的PVC是安全、有效且成功率高的一种方法。     

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?     

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     

射频消融治疗室性早搏触发特发性室性心动过速／心室颤动的病例分析

目的探讨射频消融治疗在室性早搏（室早）触发特发性室性心动过速／心室颤动（室速／室颤）中的作用。方法总结3例由室早触发室速／室颤的治疗经验,1例对室早进行射频消融（RF—CA）并植入心律转复除颤器（ICD）,另1例经射频消融未完全消除室早而选择植入ICD,第3例经射频消融成功消除室早,未再发室颤。结果随访2年,3例患者均存活,ICD未再记录到室速／室颤。结论在室早触发室速／室颤病例中,应分析室早与室速／室颤的相关性,给予个体化治疗,射频消融室早可以消除／减少晕厥和室颤的发作。     

单导管射频消融治疗右室流出道室性期前收缩

目的:观察单导管射频消融治疗右室流出道室性期前收缩（室性早搏,室早）的安全性和临床效果。方法: 经常规体检、生化检查、X线胸片、心脏彩超、长程心电图等各种检查后,入选65例患者,采用温控消融导管以起搏为主的方法进行标测,并对单导管射频消融的安全性和临床效果进行总结。结果: 消融即刻成功率97%(63/65),其中2例放弃消融术;随访15～40个月,有3例复发并再次手术,成功2例,总成功率为95%（62/65）,无复发。电生理检测和消融时间:(50±27) min;曝光时间:(8.1±3.8) min,所有患者术中及术后均未发生消融相关并发症。结论: 单导管射频消融治疗右室流出道室早安全有效,并能减少消融操作及X线暴露时间。     

体表心电图特征对特发性右心室流出道室性心动过速和室性早搏起源点的定位价值

目的 起源于右心室流出道(RVOT)不同位点的室性心动过速(VT)具有相应的心电图表现,本研究旨在摸索一种相对简单的根据体表心电图进行定位的方法 .方法 将RVOT分为游离壁和间隔而两大区,其中间隔面又分为9个区域.共320例RVOT-VT患者中,对213例既往消融成功患者的靶点与体表12导联心电图中QRS波形态之间的关系进行分析,并在消融前前瞻性地对另外107例患者的消融靶点进行预测,以检验其定位价值.结果 I导联对RVOT起源的VT有特殊的定位价值.在间隔面前部起源时,I导联以负向波为主,多为QS、Qr及rS型,随着起源点从前向后、从上向下,R波逐渐升高,其中起源于间隔侧中带(2、5、8区)时,以"M"型居多,在后壁时则表现为R波且有切迹.游离壁起源者的QRS时限明显延长,I和aVL导联的R波较间隔起源者高,而下壁导联的R波均较间隔的低(P<0.05).在前瞻性分析中,这些参数的敏感度、特异度、阳性和阴性预测值均较高.结论 RV-OT不同部位起源的VT有相应的心电图特征,其中I导联形态尤其具有定位价值,为RVOT心律失常起源提供了简便的定位标准.     

Noncontact mapping of small pulmonary artery potentials preceding ectopy from the right ventricular outflow tract

Idiopathic right ventricular tachycardia typically originates from the right ventricular outflow tract (RVOT). However, it also may originate from above the pulmonic valve. We describe a patient with a 2-year history of symptoms of palpitations associated with premature ventricular contractions (PVCs) in whom radiofrequency catheter ablation at the PVC exit site in the lateral RVOT failed despite the presence of several favorable criteria. However, using a multiple electrode array catheter, we demonstrated above the pulmonic valve clear evidence of low-amplitude preceding electrical activity ("blue ghost") that swept 3 cm inferolaterally over 20 ms to the previously identified lateral RVOT exit. Catheter mapping even at 128x gain demonstrated only very-low-amplitude potentials at this site, and pacing was unable to capture the ventricle from this region. However, ablation at this site immediately terminated the arrhythmia, and the patient has remained PVC-free after 1 year. This case supports the existence of previously hypothesized myocardial sleeves above the pulmonary valve that may be responsible for RVOT tachycardia and shows that they can be detected using noncontact mapping.     

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.     

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.