非接触标测对于典型心房扑动的标测、消融和电生理机制的新认识

目的介绍非接触标测对于典型心房扑动(简称房扑,AFL)的标测、消融和电生理机制的新认识.方法 9例典型AFL,男性7例,女性2例.使用非接触标测对窦律时峡部的双向传导、AFL时的折返激动序列进行详细标测,在导航系统指导下完成后位峡部线性消融,然后验证峡部双向传导阻滞.结果 (1)1例为顺钟向AFL,7均为逆钟向AFL,1例未能诱发AFL,所有AFL平均心房心动周期(215±36)ms;(2)非接触标测三维显示AFL在右房内的整个折返环及其与解剖结构的三维关系;(3)激动可以穿过界嵴上部并且传导相对缓慢,提示右心房平滑部是折返环的一部分;(4)非接触标测可直观显示复发病例的消融线缺口,并直接导航消融;(5)1例术中出现心房颤动,1例因不能耐受消融所致胸痛放弃手术,其余7例即刻均达到峡部双向阻滞,随访12～36月未见复发.结论非接触标测系统可直观再现典型AFL的完整折返环及其与右房解剖结构的关系,确认折返机制,对复发病例可发现消融线裂隙并导航消融.同时发现激动可横向穿过界嵴并且速度缓慢.     

非接触球囊导管标测系统指导心房扑动消融的初步经验

目的　评价非接触球囊导管标测系统在心房扑动 (房扑 )标测和射频消融中的临床应用。方法　 7例房扑患者 ,年龄 (6 0± 10 )岁 ,男 4例 ,女 3例。其中 1例为房间隔缺损修补术后 ,2例为采用常规方法消融典型房扑后复发患者。应用非接触球囊导管标测系统构建右房三维几何模型 ,标测心动过速的折返激动顺序和关键峡部 ,并利用其导航系统指导峡部的线性消融。消融后分别于峡部两侧起搏判断峡部阻滞情况。结果　 6例患者诱发出房扑 ,心动过速周长 (2 16± 2 2 )ms。6例房扑均为峡部依赖型 ,2例呈逆钟向传导 ,4例呈顺钟向传导 ;4例房扑呈双环折返激动 ;7例消融均成功 ,房扑不再诱发 ,峡部呈完全双向传导阻滞 ;手术时间 (30 0± 12 9)min ,X线曝光时间 (2 5 0± 6 5 )min ,放电次数 (2 5 7± 12 1)次。无手术并发症。随访 3～ 14个月无复发病例。结论　在房扑标测和消融中应用非接触球囊导管标测系统是安全有效的 ,不仅能确定折返环路 (特别是双环折返激动 )的顺序和关键峡部 ,而且能准确判断线性损伤的连续性 ,同时可减少X线曝光时间。     

普通型心房扑动的新现象

普通型心房扑动 (AFL)的完整折返环路以及界嵴 (CT)和AFL的关系仍不太清楚 ,笔者应用电解剖 (CARTO)标测系统执行两项研究。Ⅰ :对 12例持续AFL的病人实施右房CARTO标测及多部位拖带。于三尖瓣环 (TA)周围测量传导速度。双电位 (DP)位于右房后下壁 ,相当于解剖上的界嵴 ,从下腔静脉 (IVC)与心房肌的连接处向上、稍前延伸 ,其长度为 40 .9± 7.9mm。所有病人的DP间期从上至下逐渐增加。在 9例逆向AFL病人中 ,右心耳后基底部的后方一狭长心肌位于折返环内 ,结果来自右心耳基底前、后方的两个心房激动波融合于右房下游离壁。在另 3例病人中 (1例顺钟向、2例逆钟向 )右心耳基底部后方未发现位于折返环内 ,迫使折返环仅绕三尖瓣与右心耳基底部前方之间的心肌兴奋右房下游离壁。在AFL的折返环中 ,没有固定的缓慢传导区 ,大部分病人的缓慢传导区位于间隔部和侧壁。Ⅱ :对 7例普通型AFL及 6例非AFL病人 ,在冠状窦起搏下 ,标测右房后壁。通过在右房重建中出现DP确认CT。以 6 0 0 ,30 0ms周长以及静脉注射氟卡胺 (1mg/kg)后以 6 0 0ms周长起搏冠状窦 ,分别测量CT上、中、下部位的刺激信号至双电位中第一及第二个心房激动波的传导时间 (SD1及SD2 )和此部位的电位间期 (DPI)。在AFL病例中 ,与以 6 0 0ms周长起搏冠状     

心电图P波形态变化在典型心房扑动射频消融中意义的再评价

目的以峡部消融线上标测到稳定的宽间期双电位作为典型心房扑动(AFL)射频消融(RFCA)终点标准,对消融前后低侧位右房与冠状窦口刺激心电图P波形态变化进行比较,进而评价其临床应用意义。方法24例典型AFL患者,进行三尖瓣环至下腔静脉之间的线性消融。消融后于消融线标测双电位。消融前后,以及消融过程中分别进行低侧位右房与冠状窦口刺激,比较心电图P波形态的变化。结果RFCA成功后行低侧位右房及冠状窦口起搏,所有患者体表心电图Ⅱ,Ⅲ,aVF导联的P波在负向成分之后出现一正向波成分(100%),且P波时限延长,但是6例患者出现特征性心房激动顺序变化时(即低侧位右房刺激时呈顺钟向传导,逆钟向阻滞。冠状静脉窦刺激时呈逆钟向传导,顺钟向阻滞),消融线局部双电位为71.0±11.2ms,此时低侧位右房与冠状静脉窦口刺激也出现相同的P波变化,继续消融可见双电位延长至118.20±10.2ms,而再予刺激,并不出现P波形态的进一步变化(25%)。结论:对于典型AFL的射频消融治疗,峡部消融后进行峡部两侧刺激可以产生心电图P波形态的特征性变化。但是由于峡部为缓慢传导或者残存传导裂隙时也可以出现此种变化,加之影响P波形态的因素较多,所以这种判断方法临床实践应用的意义不大。     

探索不用Halo电极射频消融治疗典型心房扑动的方法

目的探讨不用Halo电极消融典型心房扑动(AF)的方法和右心房峡部传导时间间期的意义.方法对9例AF患者进行了心脏电生理检查和射频消融.将普通标测电极分别放置高位右房(A点)、低位右房(B点)、希氏束(C点)、冠状窦(CS34为D点),标测AF发作时右房激动顺序,起搏时和消融后测量右心房峡部传导时间间期(BD、DB). 结果不用Halo电极成功消融9例AF病例.消融后于冠状窦口处起搏时起搏信号至右房下侧壁的时间间期(DB=140.7ms±66.1ms)和右房下侧壁起搏时起搏信号至冠状窦口CS34的时间间期(BD=123.2ms±42.1ms)均较消融前(DB=66.0ms±12.5ms,BD=62.5ms±13.0ms)明显延长,P＜0.01. 结论不用Halo电极能成功消融典型AF,该方法简便、费用低;右心房峡部传导时间间期的定量测定可作为判断峡部完全性双向传导阻滞的方法之一.     

探索不用Halo电极射频消融治疗典型心房扑动的方法

目的探讨不用Halo电极消融典型心房扑动(AF)的方法和右心房峡部传导时间间期的意义。方法对9例AF患者进行了心脏电生理检查和射频消融。将普通标测电极分别放置高位右房(A点)、低位右房(B点)、希氏束(C点)、冠状窦(CS34为D点),标测AF发作时右房激动顺序,起搏时和消融后测量右心房峡部传导时间间期(BD、DB)。结果不用Halo电极成功消融9例AF病例。消融后于冠状窦口处起搏时起搏信号至右房下侧壁的时间间期(DB=140.7ms±66.1ms)和右房下侧壁起搏时起搏信号至冠状窦口CS34的时间间期(BD=123.2ms±42.1ms)均较消融前(DB=66.0ms±12.5ms,BD=62.5ms±13.0ms)明显延长,P<0.01。结论不用Halo电极能成功消融典型AF,该方法简便、费用低;右心房峡部传导时间间期的定量测定可作为判断峡部完全性双向传导阻滞的方法之一。     

心房颤动消融术后二尖瓣峡部房性心动过速的发生机制及消融治疗

目的探讨心房颤动(简称房颤)患者环肺静脉左房线性消融术后二尖瓣峡部房性心动过速(简称房速)的发生机制及其消融策略。方法122例房颤患者采用EnSite-NavX和环状电极行环肺静脉左房线性消融,术后32例复发房颤或房速,8例经EnSite-NavX激动标测及拖带标测证实存在二尖瓣峡部房速,在三维导航下于左下肺静脉口部下缘至二尖瓣环之间行线性消融,对不能成功阻断二尖瓣峡部传导者予以冠状静脉窦内消融。术中同时探查双侧肺静脉电位,如传导恢复予以再次隔离。结果8例中2例呈无休止性发作,6例为阵发性,可被程序刺激诱发。房速的周长217.5±20.6ms,其中顺钟向折返5例,逆钟向折返3例。二尖瓣峡部线性消融至完全性双向传导阻滞5例,3例心内膜途径失败者经冠状静脉窦内消融,其中1例获得成功。术后随访5.5±4.3个月,6例无房颤及房速发作,1例仍有阵发性房速发作。另1例术后房速呈无休止发作,予以胺碘酮及美托洛尔控制心室率治疗。结论环肺静脉线性消融术后发生的二尖瓣峡部房速与左房线性消融治疗房颤的致心律失常作用有关,其主要的机制是消融线相关的大折返性心动过速,阻断峡部传导可以治疗此类房速。     

射频消融治疗典型心房扑动不同消融终点的评价

评价导管射频消融治疗峡部依赖性心房扑动 (AFL)中 ,心房激动顺序的变化与双电位标测这两种消融终点的判断方法 ,以期提高成功率 ,减少复发率。选取 1997年 11月至 2 0 0 2年 9月连续收治的 4 3例典型AFL病人。按照消融终点不同 ,以及收治时间顺序分为心房特征性激动顺序变化组 (AC组 ) ,双电位组 (DP组 )。于右房三尖瓣环与下腔静脉之间的峡部进行线性消融。AC组以出现右房特征性激动顺序的变化 (即低侧位右房刺激时呈逆钟向阻滞 ,冠状静脉窦刺激时呈顺钟向阻滞 )为依据判定为峡部双向阻滞。DP组在AC组消融结果基础上 ,以消融线上标测到宽间期双电位 (>10 0ms)为依据判定为峡部双向阻滞。随访复发率。结果 :4 3例患者 ,所有患者均达到相应的射频消融终点。DP组所有患者消融成功后双电位为 116 .6± 12 .5ms。随访 14 .5± 5 .4个月 ,AC组的复发率高于DP组 (2 3.5 %vs 0 ,P <0 .0 5 )。结论 :作为峡部双向阻滞的指征 ,宽间期双电位比心房特征性激动顺序变化更准确 ,手术成功率更高。     

典型心房扑动的经导管射频消融治疗

回顾分析 35例典型心房扑动 (简称房扑 )患者电生理检查和射频消融治疗的临床结果。心内激动标测显示沿三尖瓣环 (TA)逆钟向折返性房扑 2 7例 ,顺钟向折返 2例 ,同时存在二种折返 6例。 8例行TA峡部拖带起搏者均呈隐匿性拖带 ,起搏后间期与房扑周长差值为 1± 4(- 3～ 5 )ms。采用TA峡部双线性消融、后峡部或 /和间隔峡部消融的方法治疗所有患者均成功。 15例以房扑不能再诱发为手术终点 ,随访 10例 ,3例复发 ,复发率 30 % ;2 0例达到TA峡部双向阻滞 ,随访 19例 ,1例复发 ,复发率 5 % ,两组比较P <0 .0 5。随访的 2 9例中 ,7例发生心房颤动 (简称房颤 ) ,发生率 2 4%。与无房颤发作者相比 ,合并器质性心脏病、心房扩大和有房颤病史者的比例明显增加 (6 / 7比 9/ 2 2 ,6 / 7比 4/ 2 2和 7/ 7比 2 / 2 2 ,均P <0 .0 5 )。结果表明 ,心内激动标测结合拖带起搏技术可确定典型房扑的诊断 ,后峡部或间隔峡部消融是治疗房扑的有效方法 ,以TA峡部双向阻滞为手术终点较房扑不能被再诱发为终点可明显降低复发率。房扑消融术后发生房颤与合并器质性心脏病、心房扩大和术前存在房颤有关     

心房颤动导管消融术后复发嵴部依赖折返的电生理特点和成因分析

目的阐明心房颤动(房颤)导管消融术后复发二尖瓣环峡部线(MI)嵴部缝隙依赖折返的电生理特点和产生原因。方法选取82例曾于房颤导管消融术中行MI消融并因术后复发规则房性心动过速(OAT)而行二次消融的患者,行电生理检查和二次导管消融,一旦判定为MI嵴部传导缝隙依赖的OAT,则在三维电磁导管定位系统(CARTO)引导下在MI消融线上和嵴部取点,计算左心房内膜周长占心动过速周长(TCL)比例,术后至少随访6个月。另外选择2012年10月至2012年12月间于房颤导管消融术中行MI消融且已达阻滞标准者36例。将消融导管置于嵴部,重复鉴别性起搏过程,观察嵴部是否存在传导缝隙。结果 82例因房颤导管消融术后复发OAT行二次消融的患者有7例(8.5%)为MI嵴部缝隙依赖折返,心动过速周长(TCL)为(247.9±19.2)ms,左心房内膜面激动时间为(145.4±17.7)ms,占TCL(58.5±3.2)%。体表F波形态和激动标测符合围绕二尖瓣环大折返特点,但MI消融线上拖带起搏后间期(PPI)较长[PPI-TCL(34.3±6.6)ms],且存在较宽双电位[间距(99.7±7.4)ms],而嵴部拖带PPI-TCL明显较短[(11.4±3.9)ms,P0.001];6例于嵴部消融终止,1例于冠状窦远端对应位置消融终止,随访(11.1±4.5)个月无复发。另外,36例行MI消融且满足双向阻滞标准的患者,于嵴部重新行鉴别性起搏,发现5例(13.9%)存在嵴部传导缝隙。结论 MI嵴部缝隙依赖折返是一类以嵴部缝隙为关键峡部、而既往MI消融线在折返路径之外的独特OAT,其成因可能与嵴部尚存传导缝隙却符合MI阻滞判定标准的MI假性阻滞现象有关。     

Linear Ablation of Right Atrial Free Wall Flutter: Demonstration of Bidirectional Conduction Block as an Endpoint Associated With Long‐Term Success

Ablation of Right Atrial Free Wall Flutter. Introduction: Ablation for atypical atrial flutter (AFL) is often performed during tachycardia, with termination or noninducibility of AFL as the endpoint. Termination alone is, however, an inadequate endpoint for typical AFL ablation, where incomplete isthmus block leads to high recurrence rates. We assessed conduction block across a low lateral right atrial (RA) ablation line (LRA) from free wall scar to the inferior vena cava (IVC) or tricuspid annulus in 11 consecutive patients with atypical RA free wall flutter. Method and results: LRA block was assessed following termination of AFL, by pacing from the ablation catheter in the low lateral RA posterior to the ablation line and recording the sequence and timing of activation anterior to the line with a duodecapole catheter, and vice versa for bidirectional block. LRA block resulted in a high to low activation pattern on the halo and a mean conduction time of 201 ± 48 ms to distal halo. LRA conduction block was present in only 2 out of 6 patients after termination of AFL by ablation. Ablation was performed during sinus rhythm (SR) in 9 patients to achieve LRA conduction block. No recurrence of AFL was observed at long‐term follow‐up (22 ± 12 months); 3 patients developed AF. Conclusion: Termination of right free wall flutter is often associated with persistent LRA conduction and additional radiofrequency ablation (RFA) in SR is usually required. Low RA pacing may be used to assess LRA conduction block and offers a robust endpoint for atypical RA free wall flutter ablation, which results in a high long‐term cure rate. (J Cardiovasc Electrophysiol, Vol. 21, pp. 526‐531, May 2010)     

CARTO标测指导射频消融治疗非峡部依赖性心房扑动的初步研究

初步探讨非峡部依赖性心房扑动 (简称房扑 )———非典型房扑CARTO标测的方法学和射频消融效果。 4例经电生理标测证实的非典型房扑患者 ,男、女各 2例 ,年龄 2 4～ 5 7岁。 1例为先天性心脏病 (简称先心病 )三房心外科术后 ,1例为慢 快综合征。房扑发作时在右房或左房CARTO标测 ,三维重建右房或左房 ,寻找房扑折返径路的关键峡部区域行线性消融。结果 :3例为右房非峡部依赖性房扑 ,1例消融径线为 2条 ,即三尖瓣环至下腔静脉(IVC)口和右房后外侧至IVC ,1例消融径线为右房前中外侧 ,1例为右房下外侧。 1例左房房扑 ,消融径线位于右上肺静脉口下方至卵园窝。 4例均即时消融成功。随访 8～ 2 4个月 ,有 1例先心病术后房扑复发 ,再次行CARTO标测发现房扑折返环位于左房 ,划线消融未成功。结论 :CARTO标测非峡部依赖性房扑有一定的优势 ,能显示房扑折返环和关键峡部 ,并能指导线性消融     

Apparent Bidirectional Conduction Block Following Radiofrequency Catheter Ablation of Typical Atrial Flutter

Objective: The purpose of this study is to determine the reliability of activation sequence mapping in assessing the presence of bidirectional conduction block (BCB) in typical atrial flutter (AFL) ablation. Introduction: Radiofrequency ablation (RFA) can cure typical AFL by creating BCB across the right atrial isthmus. Effective conduction block across this region can prevent AFL recurrence, but accurate assessment of isthmus conduction may be flawed. Methods: BCB was measured before and after RFA by pacing at multiple rates on both sides of the isthmus during sinus rhythm. Pacing was performed from a low lateral tricuspid annulus site (proximal to the isthmus) and a coronary sinus Os site (distal to the isthmus), while recording simultaneously from 8–10 right atrial sites bordering the isthmus (4–5 free wall sites; 4–5 septal sites) as well as from an isthmus site. After ablation reinduction of atrial flutter was attempted from both sides of the block with rapid atrial pacing after BCB was established in all patients. In some patients lines of conduction block were evident at the isthmus (using the ablation catheter to map). Results: Of 65 patients undergoing RFA of AFL, 59 had typical AFL. In all 59 patients, BCB was demonstrated at all pacing cycle lengths 30[emsp4 ]min after RFA applications. In 6 of these 59, AFL was inducible with atrial pacing despite apparent BCB. Further RFA resulted in non inducibility in all 6 patients. In the remaining 53/59 patients, BCB was associated with noninducibility at 30[emsp4 ]min. A total of 8 recurrences were seen during a mean 19.3[emsp4 ]±[emsp4 ]8.3 (SD) month follow-up. Conclusion: Apparent BCB as determined by activation sequence mapping outside of the isthmus is an excellent marker, but, as measured, may be a misleading method of assessing the presence or absence of conduction through the isthmus. It is necessary to attempt reinduction of AFL after apparent success. Elimination of typical AFL does not preclude other AFLs.     

Right atrial flutter due to lower loop reentry: mechanism and anatomic substrates

BACKGROUND: The mechanisms of an atrial flutter (AFL) that is more rapid and at times more irregular than typical AFL are unknown. METHODS AND RESULTS: Twenty-nine patients with AFL were studied. Atrial electrograms were recorded from a 20-pole catheter placed against the tricuspid annulus (TA), with its distal electrodes lateral to the isthmus between the TA and the eustachian ridge (ER), and from the His bundle and coronary sinus catheters. Atrial extrastimuli were delivered in the TA-ER isthmus during typical AFL. Episodes of a right atrial flutter rhythm that was different from typical AFL were induced in 3 patients and occurred spontaneously in 3 patients. This sustained AFL, designated as lower-loop reentry (LLR), involved the lower right atrium (RA), as manifested by early breakthrough in the lower RA, wave-front collision in the high lateral RA or septum, and conduction through the TA-ER isthmus. Linear ablation resulting in bidirectional conduction block in the TA-ER isthmus terminated spontaneous LLR in 3 patients and rendered LLR noninducible in all patients. The cycle length of LLR was shorter than that of typical AFL (217+/-32 versus 272+/-40 ms, P<0. 01). Alternating LLR and typical AFL in 1 patient resulted in cycle length oscillation. CONCLUSIONS: LLR is a subtype of right atrial flutter and depends on conduction through the TA-ER isthmus.     

Treatment of atrial fibrillation by catheter ablation of conduction gaps in the crista terminalis and cavotricuspid isthmus of the right atrium

A 74-year-old man with atrial fibrillation (AF) underwent electrophysiologic study and catheter ablation with a noncontact mapping system. AF was induced by coronary sinus pacing, and noncontact mapping showed ever-changing movement of multiple wavefronts with one dominant reentrant circuit around the tricuspid annulus, splitting wavefront conduction through the gaps in the crista terminalis, and then fusion and stasis of wavefronts. After creation of bidirectional conduction block over crista terminalis gaps and the cavotricuspid isthmus, AF or atrial flutter was noninducible. No further AF recurrence was noted during 6-month follow-up.     

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。     

三维标测系统指导下多环心房扑动的射频消融治疗

目的探讨三维标测系统指导下多环心房扑动(AFL)的射频消融疗效。方法 4例AFL患者,在三维标测系统(CARTO或EnSite Array)指导下建立相应心房三维模型并进行激动标测及电压标测,并对折返的关键峡部作线性消融。结果 4例患者均显示出多个折返环,其中1例标测出右房3个折返环、左房1个折返环,分别围绕上腔静脉、三尖瓣环、下腔静脉及左房房顶共4种折返环;其余3例患者每例均标测出2种折返环,分别为环绕上腔静脉与三尖瓣环的8字折返、环绕下腔静脉与三尖瓣环的8字折返及环绕上腔静脉、环绕右心耳的折返环。4例消融均获成功。其中1例AFL终止后窦性静止,提示病窦综合征,术后1周安置永久起搏器。随访2～9个月,无复发。结论多环AFL的心房内折返错综复杂,应用三维标测系统可清楚地显示折返途径及关键峡部。     

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.     

Activation patterns and conduction velocity in posterolateral right atrium during typical atrial flutter using an electroanatomic mapping system.

BACKGROUND: To investigate the activation patterns and conduction velocity (CV) in the posterolateral right atrial (RA) wall during typical counterclockwise atrial flutter (AFL) using an electroanatomic mapping system. METHODS AND RESULTS: During typical AFL in 25 patients, the transverse conduction pattern and CV were classified and calculated. The line blocking transverse conduction was defined by the conduction pattern and double potentials recorded during mapping. There were 3 types (including 2 subtypes) of transverse conduction pattern based on the conduction blocks across the posterolateral RA in a line between the superior and inferior venae cava. Trans-cristal conduction activation in a horizontal direction was seen in all but 4 patients. The CV in the gap area was 0.59+/-0.21 m/s. CONCLUSIONS: Three types of transverse conduction pattern were observed during trans-ctristal conduction and the trans-ctristal CV was relatively slower than that in other parts of the RA, except for the isthmus.