Carto指引下儿童三尖瓣环起源室性早搏射频消融一例

1例3岁10个月男性患儿因频发室性早搏入院行射频消融术,室性早搏12导联体表心电图提示胸前导联呈左束支传导阻滞图形,Ⅰ、Ⅱ、Ⅲ、aVF导联主波向上,呈R型,aVL导联呈rs型,aVR导联深倒,呈QS型,QRS波时限约98 ms,术中根据消融导管的X线影像及三维电解剖证实为三尖瓣环12点钟位置起源,邻近希氏束。     

体表心电图鉴别心室流出道特发性室性心动过速的起源部位

目的 :评价 12导联心电图在鉴别左室和右室流出道室性心动过速 (VT)及鉴别左室流出道VT中主动脉瓣上起源的VT和主动脉瓣下起源的VT中的价值。方法 :回顾性分析了射频消融术获得成功的 5 6例流出道特发性VT患者体表心电图特点 ,右室流出道VT组 (RVOT VT)组 4 0例 ,左室流出道VT(LVOT VT)组 16例 ,其中主动脉瓣上组 (左冠窦内 ) 10例 ,主动脉瓣下组 6例。结果 :LVOT VT组胸前导联R波移行均早于V4导联 ,87.5 %(14 / 16 )在V1或V2 导联 ,RVOT VT组 82 .5 % (33/ 4 0 )胸前导联R波移行≥V4导联 ,无一例在V3 导联前移行 ;RVOT VT组V1和V2 导联R波时限指数和R/S波幅指数明显小于LVOT VT组 [(30 .4± 12 .6 ) %∶(5 7.4± 14 .2 ) %和 (13.8± 7.5 ) %∶(5 8.2± 11.4 ) % ,均P <0 .0 1]。主动脉瓣上LVOT VT组下壁导联 (Ⅱ ,Ⅲ ,aVF)R波振幅明显高于主动脉瓣下组 ;V5和V6导联或单独V6导联有s波对确定主动脉瓣下起源的LVOT VT敏感性 10 0 % (6 / 6 ) ,V5和V6导联均无s波对确定主动脉瓣上起源的LVOT VT特异性 90 % (9/ 10 )。结论 :体表心电图对初步确定心室流出道VT的起源部位可以提供很大的帮助。     

R波移行导联和V2转换率对流出道起源室性心律失常的定位价值

目的 通过回顾性研究对R波移行导联及V2转换率定位流出道起源的室性心律失常(VA)的流程进行准确性验证,旨在寻找一个简洁准确的方法区分右心室流出道(RVOT)和左心室流出道(LVOT)起源的VA.方法 回顾性分析接受射频导管消融治疗的起源于流出道的VA患者心电图资料,计算R波移行导联及V2转换率,并与射频消融结果相比,验证心电图流程的准确性.结果 52例患者中有24例VA时R波移行≥V4导联,均在RVOT消融成功.10例R波移行≤V2导联患者中,9例在LVOT消融成功.18例R波移行在V3导联的患者中,5例VA时胸前导联移行晚于窦性心律时的患者全部在RVOT消融成功,6例V2转换率＜0.6的患者均在RVOT消融成功,而V2转换率≥0.6的7例患者中,5例在LVOT消融成功,2例在RVOT消融成功.该心电图流程定位结果与射频消融定位结果一致性程度高,Kappa值为0.8627,区分RVOT和LVOT起源的VA的正确指数为0.9211.结论 利用R波移行导联及V2转换率相结合的方法能准确区分RVOT和LVOT起源的VA,R波移行≥V4导联和VA时胸前导联移行晚于窦性心律时能100％除外VA起源于LVOT.     

体表12导联心电图对特发性流出道室性心动过速的起源灶定位作用

目的分析患者的12导联体表心电图(ECG)形态特征,旨在提出简便的ECG指标来预测特发性流出道室性心动过速起源。方法回顾我院54例经射频导管消融(消融)手术治愈的起源于心室流出道的特发性室性心动过速ECG资料,总结不同部位起源特发性流出道室性心动过速的ECG形态特征。结果不同起源灶有特征性的ECG形态①左心室流出道心内膜起源的ECG100%呈右束支传导阻滞图形,87.5%胸前V6导联出现S波;②左冠状窦起源的100%符合V1或V2导联R/S波幅指数≥30%和R波时限指数≥50%这两个条件;③右心室流出道游离壁起源下壁导联的R波多有切迹,且V2导联的S波振幅较深,胸前导联移行晚。结论12导联体表ECG特征,对特发性流出道室性心动过速起源灶定位有较高的预测价值。     

起源于右冠窦和左主干室性早搏各一例

2例室性早搏(简称室早)均呈左束支传导阻滞图形,Ⅱ、Ⅲ、aVF呈R型。1例心电图Ⅰ导联r型、aVL导联呈rS型,aVR呈QS型,V1导联呈QS型,V2、V3导联呈rS型,V5、V6导联呈R型,胸前移行导联V4导联,右室流出道间隔部消融未成功,成功靶点在右冠窦。另1例心电图Ⅰ、aVL导联呈QS型,V1导联呈rS型,V3呈Rs型,胸前移行导联V3导联,发现理想靶点为左主干根部,终止手术。结论:通过体表心电图QRS波的形态、振幅、极性、移行、顿挫可初步判断室早起源部位,但最终仍需腔内精确的标测和消融。     

心电图对右心室流出道室性早搏消融结果的预测价值

目的 了解体表心电图对右心室流出道室性早搏(室早)消融结果的预测价值.方法 收集2002年1月～2007年3月室性早搏发作时心电图V1导联QRS波均呈左束支阻滞(LBBB)形态的无明显器质性心脏病患者72例,按射频消融治疗结果分为成功组和对照组,其中成功组63例,对照组9例(失败4例、复发5例),分析两组体表心电图12导联R波幅度、R波时限、S波时限、QRS时限,V2导联R波时限占QRS时限的百分比、胸前导联R波移行导联、V1导联R/S的比值、V1导联R波缺失、aVL和aVR比例(Qs或rS幅度)、I导联R波单相、I和aVL导联Qs波以及起搏时12导联心电图与自然发作室早心电图图形相同的导联数,比较两组患者心电图的特点.结果 胸前导联移行导联在≥V3成功率较高,≤V2很难成功(P=0.002),V1导联R波缺失预示成功率高(P=0.011),V2导联R波时限占QRS时限的百分比大于30%更易成功(P=0.025),两组体表心电图的aVL:aVR(QS或rS的幅度比),aVL导联Qs形态和起搏时12导联心电图与自然发作室早心电图图形相同的导联数有显著差异性(P《0.05),12导联R波幅度、R波时限、S波时限、QRS时限等参数中仅Ⅱ导联的S波时限有显著性差异(P=0.027),其他指标未达到统计学意义(P》0.05).结论 术前分析心电图有助于临床医生选择合适室早患者作为消融对象,以降低失败风险,提高成功率.     

流出道起源室性早搏心电图特征及其对射频消融靶点的判断价值

目的：研究室性早搏（室早）的心电图特征及对流出道室早的定位价值。方法回顾68例成功消融的右室流出道（RVOT）和左室流出道（LOVT）室早患者的图形,测量胸前导联 R／S值、R／S 转换部位、V2导联 QRS 波时限、V2导联 R 波振幅指数和 R 波时限指数,探讨其与射频消融靶点的关系。结果54例起源于 RVOT 与14例起源于 LVOT 的室早患者一般情况无显著差异。RVOT 室早比 LVOT 室早时限更短（P ＜0．05）,R／S 转换在 V1～V2导联的有12例,其中LVOT 11例,特异性91．67％,敏感性78．57％;转换在 V3导联的24例,其中 RVOT 21例,特异性87．50％,敏感性38．89％;转换在 V4～V6导联的为32例 RVOT 患者,特异性100％,敏感性59．26％;V2导联 R 波振幅指数和时限指数对 RVOT 室早的定位价值低于对 LVOT 室早的定位价值（P ＜0．05）。结论R／S 转换在 V2或 V2之前对 LVOT 的诊断价值大;转换在 V4或 V4之后对 ROVT 的诊断价值大;对于 R／S 转换在 V2～V3导联时,V2导联 QRS 波时限、R 波时限指数和 R 波振幅指数三个指标对确定室早的起源部位具有重要的价值。     

经主动脉窦消融成功的室性心律失常体表心电图特点

目的分析经主动脉窦消融成功的室性心律失常体表心电图特点。方法 36例频发室性早搏/非持续性室性心动过速(PVCs/NSVT)的患者经主动脉逆行途径,在CARTO三维电解剖标测指导下,在主动脉根部-左室流出道衔接部进行三维解剖重建、激动顺序标测和指导消融,且消融成功(1例部分成功),并分析其体表心电图特点。结果 36例患者,经左冠窦消融成功30例(83.3%),右冠窦6例(16.7%)。PVCs在体表心电图均表现心电轴下偏的反复单一形态的QRS波形。经左冠窦消融成功的PVCs/NSVT,Ⅰ导联为R、Rs、rS、r、q或rsr波,Ⅱ、Ⅲ、aVF导联均为高振幅R波,胸前导联PVCs R波移行区位于V_1~V_3导联,且PVCs移行区均早于窦性心律移行区,V_1导联表现为R、Rs、RS、rS或qr波,V_1或V_2导联R/S波幅指数2.64±2.03,R波时限指数0.62±0.12,Ⅲ导联与Ⅱ导联R波振幅比(RⅢ/RⅡ)1.09±0.18,aVL导联与aVR导联QS波振幅比(QSaVL/QSaVR)1.32±0.46。经右冠窦消融成功的PVCs/NSVT,Ⅰ导联为R、Rs、r波,Ⅱ、Ⅲ、aVF导联均为高振幅R波,胸前导联PVCs R波移行区位于V_1~V_3导联,V_1导联表现为R、Rs、rS波,V_1或V_2导联R/S波幅指数0.51±0.38,R波时限指数0.55±0.26,RⅢ/RⅡ0.95±0.23,QSaVL/QSaVR1.12±0.39。PVCs经左冠窦消融成功的V_1或V_2导联R/S波幅指数要高于右冠窦(P<0.05)。结论经左冠窦消融成功的室性心律失常多于右冠窦。体表心电图的相关特征有助于决策主动脉窦内的室性心律失常的具体消融部位。     

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     

心室流出道频发室性早搏、室性心动过速的心电图特征及射频消融治疗

目的探讨心室流出道频发室性早搏和/或室性心动过速的心电图特征及射频消融治疗的有效性及安全性。方法对14例(13例右心室流出道频发室性早搏和/或室性心动过速,1例左心室流出道频发室性早搏)的心电图特征进行分析并行射频消融治疗。结果右心室流出道室性早搏及室性心动过速体表12导联心电图QRS波特征:Ⅰ导联呈rs、m、QS及R型,aVRa、VL均呈QS型,Ⅱ、Ⅲ、aVF、V5-6导联均呈单向R波型,胸前导联R波移行区常在V3、V3导联之后,V1、V2导联R高度/S高度比值常<0.3。左心室流出道频发室性早搏和/或室性心动过速的QRS波特征与右心室流出道频发室性早搏和/或室性心动过速类似,但其胸前导联R波移行区常在V2导联之前,V1、V2导联(尤其V2导联)R高度/S高度比值常≥0.8。13例消融成功,手术操作时间45~156min,X线曝光时间8~28min。术后随访2~36个月,无复发病例。结论起源于心室流出道的频发室性早搏和/或室性心动过速有其独特的心电图表现,射频消融治疗能安全、有效地根治此类心律失常。     

主动脉窦部室性早搏与右心室流出道间隔部室性早搏心电图对比分析

目的：探讨主动脉窦部室性早搏（简称“室早”）和右心室流出道间隔部室早心电图特征的差别。方法选取12例右心室流出道间隔部室早（ A组）心电图作为对照,分析12例主动脉窦部室早（ B组）的心电图特征。结果与A组相比,B组V1、V2导联的R波时间指数增大[V1导联：（0．23±0．10） vs．（0．49±0．28）;V2导联：（0．24±0．12） vs．（0．57±0．23）;P均＜0．05]。 V1、V2导联的R／S波幅指数A组小于B组[ V1导联：（0．10±0．02） vs．（0．87±0．55）;V2导联：（0．21±0．14） vs．（1．13±1．49）,P均＜0．05]。 A组胸前导联R波移行在V3导联或其后,B组胸前导联R波移行在V1或V2导联。 A组V1、V2导联的R波移行指数小于B组[V1导联：（0．25±0．15） vs．（1．30±0．68）; V2导联：（0．31±0．20） vs．（1．71±1．14）, P均＜0．05]。结论主动脉窦部室早与右心室流出道间隔部室早在V1、V2导联R波时间指数、R／S波幅指数、胸前导联R波移行位置及移行指数上有明显的差别。     

Repetitive monomorphic ventricular tachycardia originating from the aortic sinus cusp: electrocardiographic characterization for guiding catheter ablation

OBJECTIVES: We sought to investigate the electrocardiographic (ECG) characteristics for guiding catheter ablation in patients with repetitive monomorphic ventricular tachycardia (RMVT) originating from the aortic sinus cusp (ASC). BACKGROUND: Repetitive monomorphic ventricular tachycardia can originate from the right ventricular outflow tract (RVOT) and ASC in patients with a left bundle branch block (LBBB) morphology and an inferior axis. METHODS: Activation mapping and ECG analysis was performed in 15 patients with RMVT or ventricular premature contractions. The left main coronary artery (LMCA) was cannulated as a marker and for protection during radiofrequency delivery if RMVT originated from the left coronary ASC. RESULTS: During arrhythmia, the earliest ventricular activation was recorded from the superior septal RVOT in eight patients (group 1) and from the ASC in the remaining seven patients (group 2). The indexes of R-wave duration and R/S-wave amplitude were significantly lower in group 1 than in group 2 (31.8+/-13.5% vs. 58.3+/-12.1% and 14.9+/-9.9% vs. 56.7+/-29.5%, respectively; p < 0.01), despite similar QRS morphology. In five patients from group 2, RMVT originated from the left ASC, with a mean distance of 12.2+/-3.2 mm (range 7.3 to 16.1) below the ostium of the LMCA. In the remaining two patients, the RMVT origin was in the right ASC. All arrhythmias were successfully abolished. None of the patients had recurrence or complications during 9+/-3 months of follow-up. CONCLUSIONS: On the surface ECG, RMVT from the ASC has a QRS morphology similar to that of RVOT arrhythmias. The indexes of R-wave duration and R/S-wave amplitude can be used to differentiate between the two origins. Radiofrequency ablation can be safely performed within the left ASC with a catheter cannulating the LMCA.     

三种判断流出道室性心律失常起源部位的心电图方法比较

目的 比较3种判断流出道室性心律失常起源部位方法的准确性.方法 入选来自北京3家三甲医院2008年1月1日至2010年9月30日共110例（首都医科大学附属北京朝阳医院65例,阜外心血管病医院36例,北京军区总医院9例）成功消融的室性心律失常患者,标准12导联心电图均表现为左束支阻滞图形伴电轴下偏.3种心电图判断方法包括：①胸前导联移形区指数;②V2导联移形指数;③V2导联R波时限指数及R波振幅指数.结果 总体患者中,V2导联移形指数敏感性最高（92.3％）,V2导联R波时限指数及R波振幅指数特异性最高（93.9％）,并且其ROC曲线下面积最大（0.925）;心电图提示心脏转位的患者中,V2导联移形指数敏感性最高（94.1％）,V2导联R波时限指数及R波振幅指数特异性最高（87.5％）,V2移形指数ROC曲线下面积最大（0.892）.结论 3种方法中,V2移形指数敏感性最高,V2导联R波时限指数及R波振幅指数特异性最高.总体患者中,V2导联R波时限指数及R波振幅指数ROC曲线下面积最大;心电图提示心脏转位的患者中,V2移形指数ROC曲线下面积最大.     

射频导管消融治疗的特发性室性心律失常心电图特征分析

目的：探讨不同起源的特发性室性期前收缩（PVCs）和（或）室性心动过速（VT）的心电图特征,提出鉴别流程。方法根据射频导管消融PVCs/VT有效靶点或心室最早激动点的X线胸片进行定位,分析不同起源PVCs/VT的12导联心电图QRS波群。结果828例接受导管消融,580例起源于右心室,248例起源于左心室,左、右心室起源者胸导联移行指数＜0的分别占97.58%及7.24%;左和右心室流出道起源者下壁导联多数呈R型,V1上,多数右心室流出道起源者呈rS型,右室间隔起源呈QS型,主动脉瓣上起源者常呈rS或RS型;下壁导联上,左前分支起源者常呈qR型,左后分支起源者常呈rS型。结论结合体表心电图胸导联移行指数、下壁导联和V1上的QRS波群特征可初步判断特发性PVCs/VT的起源部位。     

心电图对流出道室性心律失常起源部位的预测价值

目的 分析已行导管消融术的流出道室性心律失常患者的临床特点及电生理学特点,探讨三种已知心电指标:移行区指数、V2S/V3R指数、R波时限振幅指数对OTVA起源部位预测价值的优劣性,为临床诊疗提供参考依据。 方法 回顾性分析宁夏医科大学总医院2011年1月1日至2017年12月31日已行导管消融术且术中心内电生理证实为OTVA的54例住院患者病例资料,分析其术前12导联体表心电图,测量并计算R波时限指数与振幅指数、V2S/V3R指数、胸前导联移行区指数。通过以上指标判断心电图对于术前预测OTVA起源部位的灵敏度、特异度、阳性预测值、阴性预测值、准确度。 结果 以R波时限指数≥50%且振幅指数≥30%;V2S/V3R指数≤1.5;移行区指数<0为标准鉴别OTVA起源于LVOT时,三种指标的灵敏度、特异度、阳性预测值、阴性预测值和准确度同名指标间的差异均无统计学意义。 结论 三种心电图指标预测OTVA流出道起源的预测价值无显著差异。     

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.     

起源于右室流出道间隔部特发性室性早搏心电图及心电向量图研究

目的：探讨经射频消融证实的起源于右室流出道间隔部的特发性室性早搏（室早）的心电图特征及心电向量图特征。方法采用 CARDIO-View 心电工作站收集并分析14例经射频消融术证实为右室流出道间隔部特发性室早患者的12导联心电图及 Frank 导联心电向量图参数。结果起源于右室流出道间隔部的特发性室早呈类左束支阻滞图形。12导联心电图胸导联移行指数≥0的有12例（85．7％）,V2导联 R 波时限指数＜50％的14例（100％）, V2导联 R／S 波振幅指数＜30％的有13例（92．9％）,SV2／RV3指数＞1．5的有12例（85．7％）。心电向量图特征为：QRS 环运行方向在 F 面呈 CW 和 CCW 的各有5例（35．7％）,H 面呈 CCW的有10例（71．4％）,S 面均呈 CW（100％）;起始0．04 s,QRS 环振幅逐渐增大,QRS 环方位大部分指向左前下;0．01～0．04 s 向左向量逐渐增加,向前向量逐渐减少;QRS 环最大向量及大部分面积位于左下后。结论心电图对起源于右室流出道间隔部的室早定位诊断具有较高的准确率。起源于右室流出道间隔部的室早有典型的心电向量特征。     

Left ventricular epicardial outflow tract tachycardia: a new distinct subgroup of outflow tract tachycardia

The present study investigated the incidence and ECG characteristics of ventricular tachycardias (VTs) originating from the left ventricular (LV) epicardium. Thirty-one consecutive patients with VT or premature ventricular contraction originating from the outflow tract (OT-VT) underwent catheter ablation. Twenty-one OT-VTs were ablated from the endocardium in the right ventricular (RV) OT and 3 were ablated from the endocardium in the LVOT. In the remaining 7 patients, 4 (13%) OT-VTs were LV epicardial in origin, and 1 of these was ablated from the left sinus of Valsalva. The ECG characteristics of OT-VT of epicardial origin included prominent tall R-waves in the inferior leads, an R-wave in V1 and an S-wave in V2, precordial R-wave transition in V2-4, a deep QS-wave in aVL, and no S-wave in V6. In addition, there was an atypical left bundle branch block morphology with an inferior axis. These findings were observed during pacing from several sites in the LV epicardium. Furthermore, pacing from the left sinus of Valsalva caused a relatively tall R in V1, deep S-wave in V2 and a tall R-wave with a shallow S-wave in V3, as well as tall R-waves in the inferior leads, which represented intermediate characteristics between RV endocardial OT-VT and LV endocardial OT-VT. In conclusion, OT-VT originating from the LV epicardium is not uncommon and has characteristic ECG findings. Some of them can be ablated from the left sinus of Valsalva.     

起源于左右心室流出道心动过速和早搏的射频导管消融治疗

目的 探讨射频导管消融（RFCA）治疗心室流出道特发性室性心动过速（室速）和室性早搏（室早）的临床效果、心电图及电生理特征。方法 58例患者中室速10例,室早48例。起源于右室流出道（RVOT）43例,左室流出道（LVOT）15例,其中起源于主动脉瓣上Valsalva左冠窦（LSV）12例。5例RVOT室速是在非接触标测系统Ensite3000指导下进行消融的。结果 （1）58例患者中55例成功,3例失败,9例复发。（2）其中1例患者术中出现急性心包压塞。（3）起源心室流出道的室速和室早具有典型的心电图特征,其中Ⅱ、Ⅲ、aVF导联单向R波是流出道室性心律失常的共同特点。（4）V1或V2导联的R波时限指数与R／S波幅指数可作为区别LSV与RVOT室速和室早的有效指标。结论 射频导管消融治疗心室流出道特发性室性心律失常是一种安全、有效的方法。非接触标测系统对于血流动力学不稳定的复杂性室性心律失常的标测与治疗具有重要的意义。     

Electrocardiographic pattern as a guide for management and radiofrequency ablation of idiopathic ventricular tachycardia

BACKGROUND: Idiopathic ventricular tachycardia (VT) often originates from the right ventricular outflow tract (RVOT), but foci deep to the endocardium, in the epicardium, or in the left ventricle are not uncommon. Although these extra-RVOT foci can be targeted with ablation, risks involved are higher and success rates lower. Simple electrocardiographic (ECG) criteria allowing (1) discrimination of RVOT foci from extra-RVOT foci and (2) assessment of the chance of success of a right heart ablation procedure are desirable. METHODS: Twenty-five consecutive patients referred for radiofrequency (RF) ablation of idiopathic VT or severely symptomatic idiopathic ventricular premature contractions were included. Localization of VT origin and success rates of VT ablation in the RVOT were analyzed according to the ECG pattern. RESULTS: The analysis of the R wave in V2 was the strongest single predictor of whether the VT had an RVOT or an extra-RVOT origin. An R wave amplitude < or =30% of the QRS amplitude designated the VT focus in the RVOT with positive and negative predictive values of 95 and 100%, respectively. Analysis of R wave duration in V2 had similar predictive values, whereas the R/S transition zone in precordial leads had slightly lower predictive values. Seventeen of 20 arrhythmias (85%) with an R wave amplitude < or =30% of the QRS amplitude in V2 could be successfully abolished by an exclusively right heart procedure. CONCLUSIONS: The analysis of ECG pattern makes it possible to guide the management of patients with idiopathic VT in predicting the arrhythmias that can be safely targeted with RF ablation from the RVOT with high success rates.