心内直视下射频消融左心房后壁治疗风湿性心脏病慢性心房颤动的临床研究

目的 　 探讨心瓣膜置换手术过程中心内直视下射频消融左心房后壁治疗风湿性心脏病(风心病 )慢性心房颤动 (房颤 )的可行性及临床疗效。　方法　选择风心病伴慢性房颤患者 38例 ,房颤持续时间 (2 91± 6 4 2 )年 ,于瓣膜置换术中在心内直视下射频消融左心房后壁 ,即运用自制射频消融探针做围绕 4个肺静脉口的环形消融线及连接消融环最低点与二尖瓣环的消融线 ,输出功率 30～ 4 0W ,每次放电时间 4 5～ 6 0s;同时应用胺碘酮 3个月辅助治疗。　结果　消融时间为 (10± 4 )min ,无相关并发症。术后心脏复跳时 35例 (92 1% )为窦性心律 ,3例为房颤 ,其中 2例于 2 4h内转为窦性心律 ,另 1例随访至今仍为房颤 ;住院期间有 2例房颤复发 ,出院后 1个月左右又有 3例房颤复发 ,其余 32例按计划服用胺碘酮满 3个月后停药 ,随访 6～ 2 2 (13± 6 )个月无房颤复发。总成功率 84 2 %(32 / 38)。　结论　心内直视下射频消融左心房后壁治疗风心病慢性房颤有较高的疗效 ,且方法简单 ,并发症少 ;术后应用胺碘酮能辅助逆转心房电重构 ,减少房颤复发。     

胺碘酮对冠心病无症状心肌缺血伴室性早搏的治疗作用

探讨胺碘酮对冠心病无症状心肌缺血 (SMI)伴室性早搏 (简称室早 )的治疗效果。将 6 1例冠心病伴室早患者随机分为 2组 ,其中 31例口服胺碘酮片作为治疗组 ,30例应用硝酸异山梨酯片作为对照组。结果 :治疗组用药后SMI的发作次数显著降低 (78.7± 7.6vs 2 0 5± 11.0次 ,P <0 .0 1)及其持续总时间显著缩短 (90 .2± 11.4vs 5 0 0 .5± 39.2min ,P <0 .0 1) ,同时室早亦显著减少 (10 5± 2 7vs 90 9± 6 2次 ,P <0 .0 1)。对照组SMI发作次数亦明显降低(135 .1± 10 .8vs 2 0 4.8± 12 .5次 ,P <0 .0 1)及持续时间缩短 (2 11.7± 30 .5vs 499± 40 .3,P <0 .0 1) ,室早减少 (76 9±6 1vs 910± 6 3次 ,P <0 .0 5 )。治疗组与对照组之间比较有显著性差异 (P均 <0 .0 5 )。未见胺碘酮严重副作用。结论 :胺碘酮对冠心病伴室早有显著疗效 ,优于硝酸异山梨酯片。     

起源于肺静脉的阵发性心房颤动导管射频消融治疗

目的　探讨环状电极 (Lasso电极 )标测指导起源于肺静脉的阵发性心房颤动 (房颤 )导管射频消融治疗的安全性和有效性。方法与结果　 2 0 0 1年 5～ 12月 ,12例药物治疗无效的阵发性房颤患者 ,男 8例 ,女 4例 ,平均年龄 (47 8± 14 9)岁 ,行心内电生理检查和射频消融术。在Lasso电极指导下标测肺静脉 ,以确定诱发房颤的房性早搏起源处。确定房性早搏的消融靶点后 ,在有房性早搏或冠状窦远端起搏或右心耳起搏下寻找优势肺静脉电位 (PVP)放电消融 ,或肺静脉口环状消融。消融终点设定为 :①肺静脉电位振幅明显减低或消失 ;②肺静脉自律性电位与心房电活动无关 ;③诱发房颤的房早消失。结果成功隔离 2 6条肺静脉 ;其中左上肺静脉 12条 ,右上肺静脉 8条 ,左下肺静脉 5条 ,右下肺静脉1条。有 2例仅消融 1条肺静脉 ,均为左上肺静脉 ;8例消融2条肺静脉 ,消融 3条与 4条肺静脉者各 1例。术程 (196 4±6 5 8)min ,X线曝光时间 (5 2 0± 14 4 )min。术后随访 2～ 8个月 ,有 1例频发房早发生 ,经口服胺碘酮后房早消失 ;4例有房颤短阵发作 ,其中 3例接受口服药物 (2例服用胺碘酮 ,1例服用索他洛尔 ) ,1例植入有抗房颤程序的DDDR起搏器 ,能够有效抑制房颤发作。术中选择性肺静脉造影发现 6例有轻度肺静脉狭窄 ,其     

胺碘酮与美托洛尔联合应用对非瓣膜病心房颤动的疗效及安全性观察

观察静脉胺碘酮与美托洛尔联合应用对非瓣膜病心房颤动 (简称房颤 )的疗效及安全性。 49例冠心病伴发房颤的患者 ,按既往是否常规服用美托洛尔或氨酰心安而分入A组 ( 2 5例 )、B组 ( 2 4例 )。全部病例先给予胺碘酮负荷量 ( 3～ 5mg/kg)静脉推注 1 0min ,然后以 60 0 μg/min的速度静滴 48h ,B组同时口服美托洛尔 6.2 5～ 2 5mg ,2次/日。行心电、血压监测 ,观察 48h房颤转复率。B组 48h后转复率为 83.3% ( 2 0 /2 4 ) ,A组为 76% ( 1 9/2 5 ) ,P >0 .0 5。A、B两组转复时间、胺碘酮用量及转复后心率比较 ,差异有显著性 ( 1 7.2± 1 0 .6hvs 9.4± 9.2h ;880 .2±395 .3mgvs5 76.4± 331 .9mg ;86.3± 1 8.2次 /分vs76.8± 1 7.9次 /分 ,P均 <0 .0 5 )。副反应发生率A组为 8.0 % ,B组为 8.3% ,P >0 .0 5。结论 :静脉胺碘酮与美托洛尔联合应用对非瓣膜病房颤安全有效 ;与单用胺碘酮相比 ,转复时间短、胺碘酮用量少。     

心房颤动时显性房室旁道的射频消融治疗

对 2 6例预激综合征患者于心房颤动 (简称房颤 )时射频消融显性房室旁道。其中左侧旁道 9例、右侧旁道17例 ,2 2例有阵发性房颤史。房颤发作伴旁道前传时的心室率为 171± 32 ( 132～ 2 37)bpm。采用经主动脉逆行法或穿间隔法消融左侧旁道、经股静脉途径消融右侧旁道 ,以最早心室前向激动点且有小A波处为消融靶点。房颤时成功消融靶点的V波较体表心电图预激波的起点提前 37.2± 8.1( 2 6～ 5 3)ms。放电 6± 3( 1～ 16 )次后 ,2 6例中有2 5例 ( 96 % )旁道前传被阻断 ,1例失败。阻断旁道前传后 30min ,3例自行恢复窦性心律 ,2 2例经直流电复律后恢复窦性心律 ,心室起搏示 2 5例中有 2 3例旁道逆传已被阻断 ,2例仍存在 ,经继续消融获得成功。随访 19.2± 11.7( 1～ 38)个月 ,除 1例复发正向前传型房室折返性心动过速 (O AVRT) ,经再次消融旁道逆传成功外 ,其他患者无O AVRT发作及旁道前传恢复的证据。结论 :心房颤动时射频消融显性房室旁道方法可行、成功率高     

房室旁道射频消融后T波改变的临床观察

分析房室旁道射频消融术前后T波改变的影响因素 ,以揭示T波的改变机制。选择房室旁道患者 116例 ,其中显性旁道 82例、隐匿性旁道 34例。术中旁道均成功阻断 ,均为单支旁道 ,消融前后均无束支阻滞者。结果 :82例显性旁道患者有 79例 (96 % )有T波改变 ,而 34例隐性旁道患者无一例有T波改变 (P <0 .0 1) ;左、右显性旁道T波改变无显著性差异 (95 %vs 10 0 % ,P >0 .0 5 ) ;T波改变程度与预激程度有关 ;有T波改变和无T波改变患者消融时间 (116± 37vs 118± 5 2s)、能量 (2 7± 5vs 2 8± 7W)和消融后CK MB(2 0± 3vs 2 1± 5IU/L)差异无显著性 ,P均 >0 .0 5。结论 :射频消融术后T波改变由电张力调整所致 ,与心肌损伤无关。     

胺碘酮和普罗帕酮治疗冠心病并室性心律失常的疗效比较

比较胺碘酮和普罗帕酮治疗冠心病心肌缺血患者室性心律失常的疗效。6 9例冠心病心肌缺血合并室性心律失常患者 ,均接受冠心病正规治疗 ,其中 35例同时口服胺碘酮片 (胺碘酮组 ) ,34例口服普罗帕酮片 (普罗帕酮组 ) ,疗程 4周。疗程开始及结束时均行 2 4h动态心电图及 12导联心电图检查。结果 :两组患者用药后 2 4h室性早搏 ,短阵室性心动过速的发作次数均明显减少 (胺碘酮组用药后与用药前比较分别为 2 70 5± 14 77个vs 6 834± 45 2 8个 ,7.4 2± 3.30次vs 1.2 9± 0 .93次 ;普罗帕酮组则分别为 6 712± 3385个vs 396 2± 1983个 ,8.0 5± 3.37次vs4 .2 2± 2 .5 9次 ,P均 <0 .0 1)。胺碘酮组的疗效高于普罗帕酮组 (P <0 .0 1)。两组未见严重副作用。结论 :胺碘酮对冠心病伴室性心律失常的疗效优于普罗帕酮。     

抗心房颤动起搏器的应用初探

为评价心房程序起搏治疗阵发性心房颤动 (简称房颤 )的有效性 ,1 1例阵发性房颤患者中 1 0例置入Selec tion90 0E(AF2 .0 )型起搏器、1例置入IntegrityTMAFXDR5346型起搏器。对患者进行术前 1个月和术后 1 ,2个月阵发性房颤事件和SF 36生活质量调查。结果 :患者术后 1 ,2个月较术前 1个月在有症状阵发性房颤事件数和生活质量评分有明显降低 (1 3 .0 1± 8.51 ,9.81± 5 .91vs 2 7.0 0± 1 3 .2 1 ;62 .82± 2 1 .57,55 .73± 1 8.48vs 1 1 0 .0 0± 1 6 .57,P值均<0 .0 5) ,术后 2个月较术后 1个月有症状阵发性房颤事件数 (9.81± 5 .91vs 1 3 .0 1± 8.51 )、阵发性房颤总数 (2 1 0 .0 0± 2 69.59vs 30 9.82± 41 8.1 4 )、房颤总持续时间 (6 .0 0± 4 .1 4dvs 7.87± 4 .2 6d)、房颤负荷 (2 0 .0 1 %± 1 3 .80 %vs 2 6 .2 4 %± 1 4 .2 0 % )及生活质量评分 (55 .73± 1 8.48vs 62 .82± 2 1 .57)均降低 (P值均 <0 .0 5)。结论 :心房程序起搏能够减少阵发性房颤事件的发生 ,降低房颤负荷 ,有望成为阵发性房颤药物治疗的重要辅助手段     

围术期应用胺碘酮预防治疗心脏术后心房颤动

目的评价心脏手术围术期预防性应用胺碘酮对术后心房颤动(简称房颤)的预防作用。方法采用双盲、随机研究,将124例心脏手术者随机分为胺碘酮组(n=64),对照组(n=60)。胺碘酮组术前每天服用胺碘酮200mg,3次/天,至少7天,术后改为每天口服200mg,1次/天,直到出院。对照组则服用安慰剂,其剂量及服药方法与胺碘酮组相同。术前服用时间为13±7天,总剂量为4.8±0.9g。结果胺碘酮组术后房颤发生率、房颤时的心室率均较对照组低(23.4%vs41.7%,112±21次/分vs135±31次/分,P均<0.05),两组围术期并发症的发生率及死亡率均无显著差异。胺碘酮组的住院时间较对照组短(14.9±3.3天vs20.5±2.6天,P<0.05)。结论心脏手术围术期预防性服用胺碘酮是安全的,并且能显著降低术后房颤的发生率及房颤发生时的心室率,缩短住院时间。     

静脉及口服胺碘酮重叠应用治疗器质性心脏病心房颤动伴快速心室率的临床疗效

观察重叠应用静脉及口服胺碘酮治疗器质性心脏病阵发心房颤动 (简称房颤 )伴快速心室率的临床疗效及安全性。 36例器质性心脏病合并房颤的患者 ,男 2 2例、女 14例 ,年龄 6 5 .3± 11.5 (49～ 80 )岁。房颤发作时心室率142 .5± 2 5 .2 (12 0～ 176 )次 /分 ,先给予静脉负荷量胺碘酮 (15 0～ 30 0mg)后 ,继之以 6 0 0 μg/min静脉点滴维持 48h ,同时口服胺碘酮 6 0 0mg/d治疗。结果 :36例患者用药后 30min、1,2 ,2 4,48h心室率分别为 12 4.1± 11.5 ,113.3±8.6 ,10 5 .1± 8.2 ,92 .7± 8.5 ,88.6± 9.4次 /分 ,较用药前明显下降 (P <0 .0 1)。 30例 (83 .3% )患者转复为窦性心律 ,于 2h ,2～ 2 4h ,2 4～ 48h ,2～ 7d转复率分别为 11.1%、2 7.8%、2 2 .2 %和 2 2 .2 %。未转复组患者左房径大于转复组(P <0 .0 5 ) ,而射血分数明显低于转复组 (P <0 .0 5 ) ,这可能是 6例患者未转复的原因。 2例患者用药后出现长RR间期 ,1例出现窦性心动过缓 ,1例出现双手震颤 ,经减药或停药后恢复。结论 :静脉及口服胺碘酮重叠应用治疗器质性心脏病房颤是有效和安全的。     

预激综合征合并心房颤动与房室旁道位置分布的关系

为探讨预激综合征合并心房颤动（简称房颤）的临床特点和机制以及与房室旁道位置分布的关系，对经导管射频消融（连续治疗）成功的２９８例预激综合征患者进行了分析，其中２６例患者既往心电图证实有房颤发作。结果表明：显性旁道合并房颤（２２／１７４，１３％）多于隐匿性旁道（４／１２４，３％），Ｐ＜０．００５；右侧旁道（１７／１０５，１６％）多于左侧旁道（９／１９３，５％），Ｐ＜０．０５；右侧显性旁道（１６／９０，１８％）多于左侧显性旁道（６／８４，７％），Ｐ＜０．０１。即显性旁道尤其是右侧显性旁道合并房颤较多。支持显性旁道患者心室收缩提前（右侧旁道心室激动发生得更早）导致心房内压升高及电不稳定是预激综合征患者房颤发生机制的论点     

Development of Rapid Preexcited Ventricular Response to Atrial Fibrillation in a Patient with Intermittent Preexcitation

Intermittent preexcitation during sinus rhythm is indicative of an accessory pathway at a very low risk for sudden death. We present the case of a 49‐year‐old man with intermittent preexcitation who subsequently developed rapid atrial fibrillation with a shortest preexcited R–R interval of 230 milliseconds. Electrophysiology study showed intermittent preexcitation at baseline and 1:1 anterograde accessory pathway conduction to 220 milliseconds in the presence of 1 mcg/min isoproterenol infusion. The pathway was successfully ablated at the lateral mitral annulus. Accessory pathways highly sensitive to catecholamines may show intermittent preexcitation at baseline with potential for rapid conduction during atrial fibrillation and sudden death. (J Cardiovasc Electrophysiol, Vol. 24, pp. 347‐350, March 2013)     

利用单极标测在心房颤动时消融显性房室旁道

对12例预激综合征患者在心房颤动时以单极标测指导消融房室旁道，其中左侧显性旁道9例、右侧显性旁道3例。在消融成功的靶点图上，单极标测的心室激动较体表心电图QRS波群显示预激成分最明显的Delta波平均提前46±7ms。全部病例消融成功。平均随访7．9±5．1个月，除1例右侧旁道4个月后恢复旁道前向传导需再次消融外，其余11例常规和动态心电图既未见Delta波，也无房室折返性心动过速和心房颤动发生。结果提示对于心房颤动合并显性房室旁道的患者，采用单极标测，其图形易于迅速辨认、测量方法亦简单，用以指导消融成功率高。     

显性旁道在心房颤动时的标测与消融

目的　探讨心房颤动 (Af)时对显性旁道 (AP)的标测与消融方法。方法　 7例 AP患者 ,年龄 2 4～ 6 0岁。均有阵发性 Af史。Af发作伴旁道前传时的心室率为 12 0～ 2 0 0 bpm。采用经主动脉逆行法消融左侧旁道 ,经股静脉途径消融右侧旁道 ,以心室前向激动点最早、且有小 A波为靶点。结果　 7例患者标测到了较体表心电图预激波起点提前 2 5～ 5 0 ms的 V波 ,首次消融以 15 W能量放电 ,均在 1s～ 8s内旁道前传阻断。3例在旁道前传阻断的同时转为窦性心律 ;1例 30 min内自行转为窦性心律 ;3例经药物转为窦性心律。行心室起搏 ,6例旁道逆传已阻断 ,1例经消融后逆传阻断。随访 5～ 45个月 ,无旁道前传恢复的证据 ,亦无室上性心动过速发作。结论　在掌握适应证的前提下 ,Af时行射频消融阻断显性旁道是可行的。     

Image Integration-Guided Catheter Ablation of Atrial Fibrillation: A Prospective Randomized Study

Background: Several studies have provided details of left atrial anatomy by means of the image integration techniques, particularly focusing on the atypical patterns of the pulmonary veins.
Objective: To compare, in a prospective, randomized fashion, the conventional method of pulmonary vein disconnection and the image integration-guided approach.
Methods: Two hundred and ninety consecutive patients (290 patients, mean age 55 ± 11 years) with drug-refractory paroxysmal or persistent atrial fibrillation were enrolled in the study and were divided into two treatment groups: group 1 (145 patients) undergoing an imaging integration-guided (CartoMerge TM) ablation; group 2 (145 patients) treated by a conventional radiofrequency catheter ablation procedure. The arrhythmia was refractory to at least two antiarrhythmic drugs (IC, amiodarone).
Results: Electrical disconnection of all identified pulmonary veins was obtained in all patients of both groups. Bidirectional block of the cavotricuspid isthmus was achieved in 34 group 1 patients and in 40 group 2 patients. Left mitral isthmus ablation was attempted in 52 group 1 patients and in 56 group 2 patients. At a mean follow-up of 14 ± 12 months, the atrial fibrillation-free survival rate was significantly higher in group 1 patients compared with group 2 patients (88% vs 69%, P = 0.017). The analysis for the subset of patients with previously ineffective ablation (98 patients: 52 group 1 patients and 46 group 2 patients) showed a significantly lower recurrence rate in group 1 versus group 2 (19% vs 48%, P < 0.01).
Conclusions: Our data indicate a superior efficacy of the image-integration guided catheter ablation of atrial fibrillation over the long term.     

人类自发的阵发性心房颤动导致的心房有效不应期及其频率适应性的变化

探讨人类自发的阵发性心房颤动 (AF)导致的心房有效不应期 (ERP)及其频率适应性的变化。对 12例在我院进行心腔内电生理检查和 或射频消融术且术中出现阵发性AF的患者 ,于AF发生前及AF终止后分别以基础周长 5 0 0 ,40 0和 30 0ms的刺激测量心房ERP。结果 :AF持续时间为 8.9± 2 .0min ,以周长为 5 0 0 ,40 0和 30 0ms行S1 S1 刺激 ,在AF发生前 ,ERP分别为2 2 3± 39,2 13± 33和 2 0 1± 2 1ms ,AF终止后 ,ERP分别为 189± 32 ,186± 35和 180± 2 3ms ,其缩短率分别为 15 .5 %± 4.0 % ,12 .9%± 3.1%和 10 .8%± 3.0 % ,与AF发生前相比 ,P均 <0 .0 1。心房ERP在低频率时的缩短程度大于在高频率时 ,各起搏周长下ERP缩短的程度比较具有显著统计学差异 (P <0 .0 5 )。AF终止后 10minERP恢复至AF前水平。结论 :人类几分钟的阵发性AF可使ERP缩短 ,并且可造成ERP频率适应不良     

静脉注射伊布利特与胺碘酮转复消融术后复发房性心动过速的对比研究

目的观察和比较伊布利特和胺碘酮转复心房颤动（房颤）射频消融术后早期复发房性心动过速（房速）的疗效和安全性。方法连续46例接受房颤射频消融后复发房速的患者,男性32例,女性14例,平均年龄（56±12）岁,分别静脉应用伊布利特（ibutilide,1．0mg／次,1～2次,10min内静脉推注）和胺碘酮（150me,／次,1～2次,10min内静脉推注）。观察转复率和转复时间,记录不良反应。结果4h内伊布利特组和胺碘酮组转复率分别为86．4％和41．7％（P=0．0023）;24h时内转复率分别为90．9％和62．5％（P=0．0376）。伊布利特组对持续时间〈24h的房速转复率为100％,胺碘酮组转复率为66．7％（P=0．0421）。伊布利特组平均转复时间为（13±8）min,胺碘酮组转复时间为（364-25）min（P〈0．01）。两组均未发生致命性不良反应,不良反应发生率差异无统计学意义。结论伊布利特和胺碘酮均能终止射频消融术后复发房速,伊布利特更快速、安全、有效。     

Clinical and Electrocardiographic Variables Can Predict Atrial Fibrillation in Patients with Atrioventricular Accessory Pathways

Background: Risk stratification of sudden death in patients with Wolff-Parkinson-White syndrome is based on the refractory period of the atrioventricular accessory pathway and the probability of spontaneous atrial fibrillation. Risk stratification based on invasive studies does not seem cost-effective in the radiofrequency ablation era, and, although sensitive, noninvasive tests are not used because of their low specificity. We sought to determine whether clinical and electrocardiographic variables can predict spontaneous atrial fibrillation in patients with an accessory pathway. Methods: We studied 420 consecutive patients treated by radiofrequency catheter ablation who had a single atrioventricular accessory pathway and the Influence of four variables: age, gender, location of the accessory pathway as determined by the site of successful radiofrequency ablation, and the presence of a manifest accessory pathway in the ECG was analyzed by multiple logistic regression analysis and a chi-square test. The development model, comprised of data from the first 359 patients, included 58 patients with spontaneous atrial fibrillation and 301 patients without spontaneous atrial fibrillation during follow-up. The likelihood ratio derived from the development model was validated in the last 61 patients. Results: Patients with spontaneous atrial fibrillation occurring before accessory pathway ablation were more often male and were older than those without atrial fibrillation. Atrial fibrillation occurred more frequently in manifest than in concealed accessory pathways, and the presence of posteroseptal accessory pathway strongly correlated with spontaneous atrial fibrillation. Conclusion: The probability of spontaneous atrial fibrillation was higher in men with a manifest posteroseptal accessory pathway and increased with age. A.N.E. 2000;5(1):45–52     

Localization and radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation Feasibility and electrogram criteria for identification of appropriate target sites

Objectives. The purpose of the present study was to assess the feasibility of and electrophysiologic criteria for successful radio-frequency catheter ablation of left-sided accessory pathways during atrial fibrillation in patients with Wolff-Parkinson-White syndrome.Background. The onset of recurrent or sustained atrial fibrillation can complicate or significantly prolong accessory pathway catheter ablation procedures.Methods. We studied 19 consecutive patients (mean age [±SD] 44 ± 16 years) with Wolff-Parkinson-White syndrome who had ongoing atrial fibrillation with rapid anterograde conduction over the accessory pathway (mean ventricular rate [±SD] 173 ± 26 beats/min, range 130 to 220) at the beginning of the localization procedure during radiofrequency catheter ablation. Localization and ablation of the accessory pathway were performed with a 7F deflectable catheter (4-mm tip) that was placed underneath the mitral valve annulus. The electrophysiologic criteria from unipolar and bipolar local electrograms were compared for successful (n = 18) and unseccessful (n = 39) sites.Results. The accessory pathways were localized in the left posteroseptal (n = 6), posterior (n = 1), posterolateral (n = 7) and lateral (n = 5) regions and successfully ablated during atrial fibrillation in 18 (95%) of 19 patients with a mean of 3 ± 2 radiofrequency pulses (range 1 to 8, median 2). Presence of an accessory pathway potential (94% vs. 44%), early activation time of the ventricular electrogram (−3.2 ± 9.2 vs.−15.3 ± 12.6 ms) and recording of atrial activation (88% vs. 61%) from the ablation catheter were helpful in identifying successful sites (p < 0.001, p < 0.001 and p < 0.05, respectively, compared with unsuccessful sites). In addition, the ventricular activation time in relation to the intrinsic deflection of the unipolar electrogram was significantly earlier at successful than unsuccessful sites (18.1 ± 4.8 vs. 24.4 ± 6.6 ms, p < 0.01). A QS complex on the unipolar electrogram was observed at 96% of successful sites and at 94% of unsuccessful sites (p = 0.74). Multivariate logistic regression analysis revealed that the presence of an accessory pathway potential (p < 0.002) and early ventricular activation time in relation to the onset of the QRS complex (p < 0.001) were independent predictors of ablation success.Conclusions. Localization and radiofrequency catheter ablation of left-sided accessory pathways is possible in patients with sustained atrial fibrillation and rapid anterograde conduction over the accessory pathway during the ablation procedure. The electrophysiologic criteria described here can be used to reliably identify successful sites for radiofrequency ablation.