慢传导带传导阻滞和为心房扑动消融终点的意义

应用Ｈａｌｏ导管标测技术，结合冠状动脉窦与希氏束电图识别心房扑动折返环的慢传导带，在下腔静脉口到三尖瓣环峡部作射频线性消融，并以慢传导带出现双向阻滞作为心房扑动消融成功的标志，治疗了１例Ｉ型心房扑动患者。随访１个月心动过速未发。     

冷盐水灌注导管对常规射频消融失败心房扑动患者的消融治疗

常规射频消融在部分普通型心房扑动患者不能产生三尖瓣环至下腔静脉之间峡部的双向传导阻滞 ,本研究观察冷盐水灌注导管对该部分患者的消融效果。 12 5例行射频消融治疗的普通型心房扑动患者中 ,7例患者从三尖瓣环至下腔静脉口或至欧氏嵴射频消融超过 15次未能产生峡部双向传导阻滞 ,定义为射频消融失败。对该 7例患者换用冷盐水灌注导管 ,以相同于常规射频消融的方法在峡部找到传导间隙后 ,行射频消融。全部患者消融成功 ,平均消融 4.5± 2次 ,导管温度 40± 1℃ ,阻抗 79± 5 .4Ω ,未观察到明显的并发症。表明常规射频消融的失败与常规射频消融不能产生峡部足够的损伤有关 ,冷盐水灌注导管对常规射频消融失败的患者可以成功地产生峡部的双向传导阻滞。     

下腔静脉、三尖瓣环峡部的射频消融治疗心房朴动

目的：报道以下腔静脉、三尖瓣环峡部双向传导阻滞作为终点的心房扑动射顿消融方法，观察该终点对长期疔效的作用。方法；对5例Ⅰ型心房扑动患者的下腔静脉、三尖瓣环峡部进行射频消融。根据右房下侧壁和冠状静脉窦口起搏的右房激动顺序和传导时间变化、评竹蚨部传导阻滞。术后门诊随访观察。结果：5例患者分别于心房扑动(2例)和赛性心律(3例)时接受射频消融治疗，消融后峡部均发生双向传导阻滞。右房下侧壁和冠状静脉赛口起搏的右房激动顺序分别呈顺时针和逆时针单一方向，右房传导时间分别延长82和78ms。随访4个月无一例复发。结论：峡部双向传导阻滞是射频消融心房扑动成功的可靠标志在赛性心律下，亦可对Ⅰ型心房扑动患者进行消融。     

先天性心脏病术后下腔静脉口-三尖瓣环峡部依赖性心房扑动的导管消融疗效分析

目的:报道先天性心脏病术后下腔静脉口-三尖瓣环峡部依赖性心房扑动的相对发生率及导管消融的疗效和安全性。方法:选择2002年1月-2006年4月在我院因先天性心脏病术后心房内折返性心动过速行射频消融的40例患者,应用常规电生理标测方法或三维标测方法(Carto和Ensite)指导导管消融,观察下腔静脉口-三尖瓣环峡部心房扑动相对发生率及其导管消融结果。结果:40例患者共诱发出50种房性心动过速,具有典型下腔静脉口-三尖瓣环峡部依赖性心房扑动心电图表现,且成功靶点在下腔静脉口和三尖瓣环峡部者31种(31／50,62．0％)。另外19种(19／50,38．0％)房性心动过速临床心电图表现与典型心房扑动不同,表现为P’波,其中11种(11／50,22．0％)成功靶点在右心房游离壁疤痕-下腔静脉峡部,瘢痕-上腔静脉峡部者2种,瘢痕与瘢痕之间峡部者2种;在瘢痕和三尖瓣环之间2种。房间隔补片和上腔静脉之间、房间隔补片和三尖瓣环之间各消融成功1种。40例患者射频消融成功,无并发症。随访1例患者心动过速复发,二次消融成功;1例患者出现持续性心房颤动伴RR长间歇,植入永久性起搏器。结论:先天性心脏病术后心房内折返性心动过速常常为下腔静脉口-三尖瓣环峡部心房扑动,导管消融具有较高的疗效和安全性。     

Swartz鞘支撑下射频消融治疗心房扑动经验初步探讨

目的　了解８ ＦＳＡＦＬ型Ｓｗ ａｒｔｚ长鞘在心房扑动消融中的作用。方法　左前斜４５度影像定位下，在三尖瓣环５～６ 点处划线消融三尖瓣环与下腔静脉开口之峡部。结果　１１ 例普通型心房扑动患者全部消融成功，随访４～１８个月，１ 例复发，再次消融获得成功。结论　在峡部消融中应用Ｓｗａｒｔｚ长鞘能使大头导管良好固定，并使峡部组织与大头接触密切，较易做到峡部线性消融，达到相当于完全性双向阻滞的满意消融效果，且缩短透视和操作时间     

对比观察射频消融右房后位峡部和间隔峡部治疗 …

对比观察射频消融右房后位峡部和间隔峡部治疗心房扑动（简称房扑）两种方法的疗效。４１例房拟患者随机分为后位峡部组（１８例）和间隔峡部组（２３例），消融线径分别为三尖瓣环一下腔静脉和三尖瓣环一欧氏嵴。成功消融绺为房扑不能诱发和峡部呈完全性双向阻滞。结果：４０例消融成功（９７．６％），无并发症。后位峡部组３例和间隔峡部组２例在首选消融方法和后，秘国一种消融方法获得成功。两组患者的放电次数和手术时间均显著     

典型心房扑动消融术后峡部计时间期的变化预测双向阻滞的价值

典型的心房扑动(房扑)是右心房内的大折返所致已成共识，下腔静脉、三尖瓣环峡部是折返环的一部分。因此，射频消融下腔静脉、三尖瓣环峡部并产生峡部双向阻滞，是成功消融典型房扑和减少复发的可靠标志。目前，多采用心房激动顺序或消融部位的双电位技术确定峡部双向阻滞的存在。通过比较房扑成功消融前、后右心房峡部传导时间，从而提出峡部传导时间的延长程度对峡部完全性     

Carto系统指导下典型心房扑动的射频导管消融9例

心房扑动是心房内大折返,折返环位于右心房或左心房,围绕有解剖或功能性的传导障碍区域形成.围绕三尖瓣环,峡部依赖性顺钟向或逆钟向大折返称为典型心房扑动,其他非峡部依赖性心房扑动为非典型心房扑动.传统射频导管消融(下称消融)在心房扑动消融中虽已获得很大的成功,但由于传统影像学定位很难确保消融线的完整.……     

29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果

目的报道29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果。方法对29例Mahaim纤维患者（房束型10例,短房室型19例）进行心内电生理检查和射频导管消融治疗。结果29例患者Mahaim纤维只存在递减性前向传导功能,其中2例合并隐匿性房室旁路（左侧游离壁和右侧中间隔各1例）,2例合并三尖瓣峡部依赖型心房扑动,3例合并房室结双径路（均为慢快型）。经Mahaim纤维前传的逆向性房室折返性心动过速时,房束型心室最早激动点在右心室心尖部,短房室型心室最早激动点在三尖瓣环消融靶点处。于三尖瓣环的心房侧成功消融所有Mahaim纤维,其中28例于三尖瓣环游离壁的心房侧消融成功,1例于右心房中间隔消融成功。13例标测到明显的Mahaim纤维电位,25例（房束型9例,短房室型16例）有效消融时出现加速性Mahaim纤维的自主心律。合并房室结双径路、隐匿性房室旁路和三尖瓣峡部依赖型心房扑动者,分别给予以慢径改良、旁路消融和右心房峡部线性消融。随访（17＋8）个月,无1例心动过速复发。结论Mahaim纤维多位于三尖瓣环游离壁。导管消融是Mahaim纤维介导的心动过速安全、有效的治疗方法。消融中出现加速性Mahaim纤维自主心律可以作为判定有效消融的预测指标。消融术前和术后应进行详尽的电生理检查以明确是否合并其他的心动过速。     

下腔静脉三尖瓣环峡部消融中心房扑动从逆钟向急转顺钟向——机制如何？

下腔静脉三尖瓣环峡部依赖的心房扑动导管消融已成为一种经常实施的手术，成功率高，是巨折返心律失常的原型。虽然导管消融峡部依赖的心房扑动已成为常规手术，但电生理实验中的不寻常表现并非少见。我们提供这一病例以揭示折返性心律失常和心房扑动的某些电生理原理。     

Electrophysiological determinant for induction of isthmus dependent counterclockwise and clockwise atrial flutter in humans

OBJECTIVE: To investigate the electrophysiological determinant underlying the electrical induction of counterclockwise and clockwise isthmus dependent atrial flutter. PATIENTS AND METHODS: The isthmus bordered by the inferior vena caval orifice-tricuspid annulus-coronary sinus ostium (IVCO-TA-CSO) has been assumed to be the site of both slow conduction and unidirectional block critical to the initiation of atrial flutter. Trans-isthmus and the global atrial conduction were studied in 25 patients with isthmus dependent atrial flutter (group A) and in 21 patients without atrial flutter (group B), by pacing at the coronary sinus ostium and the low lateral right atrium (LLRA) and mapping with a 20 pole Halo catheter in the right atrium. RESULTS: Mean (SD) fluoroscopic isthmus length between the coronary sinus ostium and LLRA sites was 28.1 (4.0) mm in group A and 28.0 (3.9) mm in group B (p = 0.95), but the trans-isthmus conduction velocity of both directions at various pacing cycle lengths was nearly halved in group A compared with group B (mean 0.39-0.46 m/s v 0.83-0.89 m/s, p < 0.0001). Pacing at coronary sinus ostium directly induced counterclockwise atrial flutter in 14 patients and pacing at LLRA induced clockwise atrial flutter in 11 patients, following abrupt unidirectional trans-isthmus block. Transient atrial tachyarrhythmias preceded the onset of atrial flutter in 10 counterclockwise and six clockwise cases of atrial flutter. None of the group B patients had inducible atrial flutter even in the presence of trans-isthmus block. The intra- and interatrial conduction times, as well as the conduction velocities at the right atrial free wall and the septum, were similar and largely within the normal range in both groups. CONCLUSIONS: Critical slowing of the trans-IVCO-TA-CSO isthmus conduction, but not the unidirectional block or the global atrial performance, is the electrophysiological determinant of the induction of counterclockwise and clockwise isthmus dependent atrial flutter in man.     

Typical atrial flutter ablation: conduction across the posterior region of the inferior vena cava orifice may mimic unidirectional isthmus block

INTRODUCTION: The aim of this study was to map the low right atrium before and after radiofrequency ablation of the inferior vena cava-tricuspid annulus (IVC-TA) isthmus in patients with typical atrial flutter (AFI) to better understand the electrophysiologic meaning of incomplete or unidirectional block following the ablation procedure and its relationship with AFI recurrence. METHODS AND RESULTS: We performed atrial mapping in 12 patients using a "basket" catheter in the IVC orifice, Halo catheter in the right atrium, and multipolar catheters in the coronary sinus (CS) and His region. In patients in sinus rhythm, atrial activation was analyzed during pacing from the CS and low lateral right atrium (LLRA) before and after ablation. Atrial activation propagated across the isthmus and posterior region of the IVC orifice simultaneously before ablation. Mapping during AF1 in four patients showed that the crista terminalis was a site of functional block. After ablation, evaluation of Halo catheter recordings in three patients showed apparent unidirectional counterclockwise block, whereas analysis of basket catheter recordings demonstrated complete bidirectional block. The apparent conduction over the isthmus during pacing from proximal CS was due to conduction along the posterior part of the IVC orifice, which activated the LLRA despite complete isthmus block. CONCLUSION: Our results demonstrate that limited endocardial mapping may yield a pattern compatible with unidirectional block in the IVC-TA isthmus, although bidirectional block is present at this anatomic level.     

单导管标测在心房扑动射频消融中的意义

目的:探讨单导管标测法在心房扑动(房扑)射频消融中的应用方法和效果。方法:阵发性心房颤动并发房扑患者行肺静脉电隔离术时采用单导管标测法消融房扑30例。所有患者行肺静脉电隔离术后,将10极冠状静脉窦(CS)导管远端2对电极放置于CS内,余位于CS外,并使之有一定的张力,使导管贴靠于三尖瓣环和低右房。用冷盐水灌注消融导管线性消融三尖瓣峡部,房扑发作患者在房扑下消融,窦律患者在CS远端电极起搏下消融,可在术中随时把大头消融导管置于希氏束部位,用于评价是否已完全达双向阻滞,即:起搏CS远端电极,刺激信号至CS近端电极A波的距离大于至希氏束A波的距离,则CS口至低右房单向阻滞;CS近端电极起搏,刺激信号至CS远端电极A波的距离大于至希氏束A波的距离,则低右房至CS口单向阻滞,从而达双向阻滞,CS近端电极起搏所需电压较高,有的患者可达24mA。结果:所用阵发性心房颤动并发房扑患者均成功行三尖瓣峡部线性射频消融,达到双向阻滞,无手术相关并发症,随访4个月～2年,无房扑复发。结论:单导管标测法对房扑患者行三尖瓣峡部线性射频消融操作简单、快速,可完全用于评价消融结果,成功率高,并且节省手术费用。     

Type I Atrial Flutter Ablation Guided by a Basket Catheter

Atrial Flutter Ablation. Bidirectional isthmus conduction block has been associated with a low recurrence rate after atrial flutter ablation. We present the ease of a type I, typical or "counterclockwise" atrial flutter ablation guided by stimulation and recordings obtained from a basket catheter, which allowed for constant electrogram recording from splines positioned along the right lateral free wall and septum. After atrial flutter termination with radiofrequency application, the ability to record and stimulate from multiple sites in the atrium using the basket catheter was useful to detect residual bidirectional slow conduction through the isthmus. Complete isthmus block could be documented after additional radiofrequency energy applications.     

Right ventricular pacing to assess transisthmus conduction in patients undergoing isthmus-dependent atrial flutter ablation: a new useful technique?

BACKGROUND: Successful radiofrequency (RF) ablation of typical, isthmus-dependent atrial flutter requires establishment and confirmation of bidirectional conduction block across the cavotricuspid isthmus. Low atrial pacing usually is performed from the bipoles of the 20-pole Halo catheter, septal and lateral to the cavotricuspid isthmus ablation line. However, occasionally this is difficult because of high pacing thresholds and/or saturation of the atrial electrograms recorded near the pacing catheter. OBJECTIVES: The purpose of this study was to assess if right ventricular (RV) pacing and resulting retrograde atrial activation can be used to assess conduction block from the septum to the lateral wall in a clockwise direction. METHODS: Thirty-five consecutive male patients (mean age 64 +/- 10 years; mean ejection fraction 42 +/- 13%; mean left atrial dimension 44 +/- 6 mm) with typical isthmus-dependent atrial flutter were studied. The following electrophysiology catheters were used: 20-pole catheter along the tricuspid annulus, quadripolar catheters at the His and/or RV apex, and 8-mm ablation catheter. Following RF ablation of the cavotricuspid isthmus, bidirectional conduction block was confirmed in all 35 patients by pacing at a cycle length of 600 ms from bipoles septal and lateral to the cavotricuspid isthmus ablation line. Conduction times from pacing artifact to adjacent bipolar atrial electrograms and reversal of atrial activation pattern were analyzed. RV pacing was performed and retrograde atrial activation pattern assessed. If retrograde AV nodal conduction was absent, isoproterenol was infused intravenously at 2 microg/min, and RV pacing was repeated. The conduction time between the double potentials across the cavotricuspid isthmus ablation line was measured. RESULTS: Mean conduction times across the isthmus during septal (S), lateral (L), and RV pacing were 145 +/- 21 ms, 144 +/- 24 ms, and 129 +/- 20 ms, respectively. Retrograde AV nodal conduction was present in 34 of 35 patients (isoproterenol 8 patients). Evidence of conduction block by a clear change in activation pattern across the isthmus was seen during RV pacing in 33 of 35 patients with bidirectional conduction block. CONCLUSION: RV pacing is a simple and easy maneuver that can be performed to assess isthmus conduction in most patients.     

Differential Pacing for Distinguishing Slow Conduction from Complete Conduction Block of the Tricuspid-Inferior Vena Cava Isthmus after Radiofrequency Ablation for Atrial Flutter—Role of Transverse Conduction through the Crista Terminalis

Background: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL).Aim: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line.Methods: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge–tricuspid valve isthmus for typical AFL. Activation patterns along the tricuspid annulus (TA) suggested incomplete CB across the isthmus. In these patients, atrial pacing was performed from the low posteroseptal (PS) and anteroseptal (AS) right atrium (RA) while the ablation catheter was placed at the ablation line where double potentials (DPs) could be recorded. The pattern of activation of the RA free wall was assessed by a 20-pole catheter positioned along the CT during pacing from the coronary sinus (CS) ostium (CSos) and low lateral RA (LLRA).Results: Faster transverse conduction across the CT resulted in simultaneous or earlier activation of the distal halo electrodes than of the more proximal electrodes, suggesting incomplete conduction block across the isthmus. CB (13) and SC (1) were detected as changes in the activation times of the first and second components of DPs (DP1, DP2) during PS RA pacing and AS RA. Similar changes in the activation times DP1 and DP2 during AS RA pacing as compared to PS RA reflected SC through the isthmus, whereas increased DP1 activation time and decreased of DP2 activation time reflected complete conduction block across the isthmus.Conclusions: Transverse conduction across the CT influences the sequence of activation along the TA after isthmus ablation. Differential pacing can distinguish SC from complete conduction block across the ablation line in the isthmus.     

欧氏瓣对老年人Ⅰ型心房扑动射频消融的影响

目的探讨欧氏瓣对Ⅰ型心房扑动(简称房扑)导管射频消融即刻效果的影响。方法28例老年Ⅰ型房扑患者(呈逆钟向折返18例,顺钟向折返10例)在透视解剖标志和Halo电极三尖瓣环标测电图指引下,在房扑发作或冠状窦口起搏时以温控方式消融位于三尖瓣口和下腔静脉口之间的后峡部,消融方向从三尖瓣叶右室侧到下腔静脉开口。预设温度70℃,每点消融30s,每次移动消融电极3～5mm。观察下列指标:①房扑终止和后峡部阻滞时消融电极在消融线上所处的位置;②房扑终止后峡部残存传导间隙在消融线上所处的位置;③房扑终止后继续消融致后峡部完全阻滞的最终消融部位。结果根据右前斜位30°透视影像测得后峡部平均弧长(即消融线)为38.6±9.7mm。28例全部达到后峡部完全阻滞的消融终点,无并发症。与欧氏瓣有关的房扑终止率为100%(17/17),与欧氏瓣有关的后峡部完全阻滞发生率为92.9%(26/28)。结论欧氏瓣是Ⅰ型房扑后峡部消融线终点的重要标志,线性消融时欧氏瓣心室侧易残存传导间隙,消融该部位的残存传导间隙是Ⅰ型房扑后峡部消融的重要环节。     

Prospective evaluation of a simplified approach for common atrial flutter radio frequency ablation with only two catheters.

Intra-atrial conduction block within the inferior vena cava-tricuspid annulus isthmus (IVCT) has been shown to predict successful common atrial flutter ablation. However, its demonstration requires the use of several electrode catheters and mapping of the line of block. The aim of this study was prospectively to test the feasibility of a simplified ablation procedure using only two catheters. METHODS: Radio frequency (RF) ablation of common atrial flutter was performed in 30 patients with the sole use of a catheter for atrial pacing and a RF catheter. RF ablation lesions were created in the IVCT. Surface ECG criteria were used to monitor the conduction within the IVCT. The end point during low lateral atrial pacing was an increment in the interval between the pacing artefact and the peak of the R wave in surface lead II >50 ms and clockwise rotation of the P wave axis beyond -30 degrees and inferiorly. Then, the line of lesions was mapped during atrial pacing with the RF catheter. Additional RF lesions were applied if mapping disclosed a zone of residual conduction. Otherwise the procedure was stopped if mapping showed parallel double potentials all along the line. Finally, the block was reassessed with a 'Halo' catheter. RESULTS: Surface ECG criteria were met in 26 patients. Mapping the line of lesions showed a complete corridor of parallel double potentials in these 26 cases and in 3 of the 4 patients in whom ECG criteria were not met. Conduction evaluated with the Halo catheter showed bi-directional complete block in these 29 patients. After a follow-up of 16 +/- 4 months there was no recurrence of atrial flutter. CONCLUSION: Surface ECG criteria combined with mapping of the line of block demonstrate evidence of bi-directional IVCT block. This simplified RF ablation of common atrial flutter is feasible with a low recurrence rate.     

Conduction Properties of the Inferior Vena Cava-Tricuspid Annular Isthmus in Patients with Typical Atrial Flutter

Conduction Properties of the Annular Isthmus. Introduction : A functional region of slow conduction located in the inferior right atrium has been postulated to be critical to the induction and maintenance of typical human atrial flutter. We reexamined the potential role of functional conduction delay in the annular isthmus between the tricuspid valve and the inferior vena cava; it is within this region that such delays have been postulated to occur, and where interruption of conduction by radiofrequency energy application has been shown to eliminate typical flutter.
Methods and Results : Thirty patients with type I atrial flutter (30 counterclockwise, 14 clockwise) were studied. Counterclockwise and clockwise isthmus activation times adjacent and parallel to the tricuspid valve were measured during three conditions: (1) atrial pacing in sinus rhythm, (2) atrial flutter, and (3) entrainment of atrial flutter. During pacing in sinus rhythm at progressively shorter cycle lengths, both counterclockwise and clockwise isthmus activation times remained unchanged; decremental conduction prior to flutter induction or loss of capture was not observed. Counterclockwise isthmus activation time did not significantly differ during flutter (68 ± 23 msec), inferolateral tricuspid annulus pacing (71 ± 23 msec), or entrainment of flutter (72 ± 23 msec). Similarly, clockwise isthmus activation times did not significantly differ between flutter (65 ± 22 msec), proximal coronary sinus pacing (73 ± 21 msec), or entrainment of flutter (64 ± 15 msec).
Conclusion : Decremental conduction is not characteristic of activation through the isthmus when activation is assessed parallel and adjacent to the tricuspid annulus. Functional slowing or conduction delay does not develop in this region during typical atrial flutter.     

Electrophysiologic Characteristics and Radiofrequency Catheter Ablation in Patients with Clockwise Atrial Flutter

RF Catheter Ablation of Clockwise Atrial Flutter. introduction: Although the mechanism and radiofrequency catheter ablation of counterclockwise (typical) atrial flutter have been studied extensively, information about the electrocardiographic and electropbysiologic characteristics and effects of radiofrequency ablation in patients with clockwise atrial flutter is limited. Methods and Results: Thirty consecutive patients with clinically documented paroxysmal clockwise atrial flutter were studied. Endocardial recordings and entrainment study using a “halo” catheter with 10 electrode pairs in the right atrium were performed. Radiofrequency energy was applied to the inferior vena cava-tricuspid annulus (IVC-TA) and/or coronary sinus ostium-tricuspid annulus (CSO-TA) isthmus to evaluate the effects of linear catheter ablation. Eighteen patients had both counterclockwise and clockwise atrial flutters, and 12 patients had only clockwise atrial flutter. Both forms of atrial flutter had similar flutter cycle lengths (232 ± 30 vs 226 ± 25 msec, P = 0.526) but reverse activation sequences. Right atrial pacing at a cycle length 20 msec shorter than the flutter cycle length from the CSO-TA isthmus, IVC-TA isthmus, and the area between the two isthmuses revealed concealed entrainment with stimulus-to-P wave intervals of 32 ± 19, 95 ± 14, and 50 ± 17 msec (P = 0.022) in the counterclockwise form, and 110 ± 12, 40 ± 20, and 60 ± 15 msec (P = 0.018) in the clockwise form. In clockwise atrial flutter, 20 patients with biphasic P waves in the inferior leads had the presumed exit site of slow conduction area located at the low posterolateral right atrium; 10 patients with positive P waves in the inferior leads had the presumed exit site located at the mid-high posterolateral right atrium. Among the 18 patients with both forms of atrial flutter, linear ablation lesions directed at the IVC-TA isthmus eliminated both forms of atrial flutter in 14 patients; in the remaining 4 patients. CSO-TA linear lesions eliminated the counterclockwise form and IVC-TA lesions eliminated the clockwise form. Among the 12 patients with the clockwise form only, CSO-TA linear lesions eliminated flutter in 2 and IVC-TA linear lesions eliminated flutter in 10 patients. Successful ablation was confirmed by creation of bidirectional conduction block in the IVC-TA and/or CSO-TA isthmus during pacing from the proximal coronary sinus and right posterolateral atrium sandwiching the linear lesions. During the follow-up period of 17 ± 8 months, 2 patients had recurrence of clockwise atrial flutter, 1 patient had new onset of atypical atrial flutter, and 2 patients had new onset of atrial fibrillation. Conclusions: Counterclockwise and clockwise atrial flutters may have overlapping slow conduction areas with different exit sites. Radiofrequency catheter ablation using the linear method directed at the IVC-TA and CSO-TA isthmuses was feasible and effective in treating both forms of atrial flutter.