Ablation of atypical atrial flutter guided by the use of concealed entrainment in patients without prior cardiac surgery

INTRODUCTION: Mapping techniques have not been systematically evaluated with respect to atypical atrial flutter (AF) not involving the inferior vena cava isthmus. The purpose of this study was to assess prospectively the use of concealed entrainment (CE) in mapping of AF and to assess the clinical benefit of ablation of clinically relevant atypical AF. METHODS AND RESULTS: In seven consecutive patients without prior cardiac surgery presenting with atypical AF, mapping was performed in the right and, if necessary, left atrium. At sites with CE, radiofrequency energy was delivered. In a posthoc analysis, the endocardial activation time, stimulus-flutter wave (F) interval, presence of split potentials and diastolic potentials, and postpacing interval were assessed, and effective sites were compared to ineffective sites. A total of 22 forms of atypical AF either could be induced or were present at the time of the study. Eleven of the 13 targeted atypical AFs (85%) were successfully ablated. The positive predictive value of CE increased from 45% to 75% in the presence of matching electrogram-F and stimulus-F intervals or if flutter terminated during entrainment pacing, and to 88% in the presence of split atrial electrograms or diastolic potentials. During short-term clinical follow-up, none of the patients had recurrence of the ablated AF. However, the majority of patients required either medication for atrial fibrillation or repeated interventions for new forms of AF. CONCLUSION: Mapping and ablation of atypical AF is feasible if sites with CE can be identified. However, the clinical benefit of successful ablations in patients with atypical flutter appears to be limited.     

Noncontact electroanatomic mapping to characterize typical atrial flutter: participation of right atrial posterior wall in the reentrant circuit

Reentrant Circuit of Typical Atrial Flutter . Background: Reentry utilizing cavotricuspid isthmus (CTI) is accepted as the mechanism underlying typical atrial flutter (AFLT). However, it is unclear how the right atrial (RA) posterior wall (PW) participates in AFLT circuit. We sought to investigate this by using noncontact electroanatomic mapping. Methods: Fifteen patients (pts) undergoing ablation for typical AFLT participated. Multipolar catheters were deployed in RA and coronary sinus. RA shell was created during AFLT. Entrainment was performed to confirm CTI dependence and assess participation of various RA regions (septum‐Sep, PW, lateral wall‐LW). Data were analyzed for (1) RA activation patterns and (2) conduction time (CT) through various RA regions. Results: Mean pt age was 70 ± 13 years (all males; CCW = 10; CW = 5). Mean AFLT cycle length was 255 ± 15 ms. Single activation wave front traversing sequentially CTI, Sep, and LW was seen in all pts and in 12 (80%; 9 CCW, 3 CW) this also traversed PW. Entrainment confirmed PW participation in 7 of these. Mean CT (in ms) through various RA regions was as follows: CTI = 69 ± 27, Sep = 50 ± 39, PW = 65 ± 35, and LW = 76 ± 35; P = NS. Conclusion: These observations offer new insights regarding the participation of PW in the reentrant circuit of typical AFLT in some patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 422‐430)     

心内非接触式标测指导右心房峡部依赖型心房扑动的消融

目的 心内非接触式标测能提供高密度的心内膜等电位标测,可采用此技术指导对有大折返环路的右心房峡部依赖型心房扑动(atrial flutter, AFL)进行消融。方法 22例患者(男性21例,女性1例)平均年龄15～65(38.0±12.8)岁。全部患者均在术前记录到典型的峡部依赖型AFL心电图。其中6例有心脏外科手术史,1例有复杂先天性心脏病,2例伴有明显的心脏扩大,8例患者曾经导管消融失败或复发。全部患者均采用右心房内非接触式标测引导在三尖瓣环-下腔静脉口(TVA-IVC)之间进行线性消融并检验消融线的完整性。结果 22例患者中18例标测到自发的AFL,4例由心房刺激诱发。全部病例中20例为逆钟向型AFL,2例顺钟向型。心内非接触式标测在所有病例均观察到经过峡部的大折返环路且行进方向与体表心电图吻合。在峡部进行TVA-IVC线性消融后,分别在冠状静脉窦口和右心房下外侧起搏时以非接触式标测证实消融线的完整性,全部患者的消融均获得即时成功,且不再服用抗心律失常药物,平均随访3～36(21.1±9.1)个月,无AFL复发,2例心脏扩大者均基本恢复正常。结论 心内非接触式标测技术可以直观、准确地观察到心房扑动的折返环路且指导进行有效的线性消融。     

Catheter ablation of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.

AIMS: Antiarrhythmic drug treatment for atrial fibrillation can cause atrial flutter-like arrhythmias. The aim of this study was to clarify the effect of catheter ablation of the tricuspid annulus-vena cava inferior isthmus on amiodarone-induced atrial flutter and to determine the incidence of atrial fibrillation after catheter ablation of amiodarone-induced atrial flutter in comparison to regular typical flutter. METHODS AND RESULTS: Among 92 consecutive patients with typical atrial flutter who underwent isthmus ablation 28 patients had atrial flutter without a history of previous atrial fibrillation (group I), 10 patients had atrial flutter following the initiation of amiodarone therapy for paroxysmal atrial fibrillation (group II) and 54 patients had atrial flutter and atrial fibrillation (group III). Atrial cycle length during atrial flutter in amiodarone-treated patients (group II) (277+/-24 ms) was significantly longer as compared to the cycle length of atrial flutter in group I (247+/-33 ms) and group III patients (235+/-28 ms). The rate of successful transient entrainment and overdrive stimulation to sinus rhythm was not different between patients with (60%) or without amiodarone therapy (group I: 71%, group III: 53%). Successful isthmus ablation with bidirectional conduction block eliminating right atrial flutter was achieved in 90% of amiodarone-treated patients and 93% of patients without amiodarone therapy. In the amiodarone-treated patient group atrial conduction times during pacing in sinus rhythm were significantly prolonged by 20-30% before and after ablation in all regions of the reentrant circuit. During a mean follow-up of 8+/-3 months post-ablation, atrial fibrillation recurred in two of 10 patients on continued amiodarone therapy after successful isthmus ablation. Thus, successful catheter ablation of atrial flutter due to amiodarone therapy was associated with a markedly lower recurrence rate of paroxysmal atrial fibrillation (20%) as compared to patients with atrial flutter plus preexisting paroxysmal atrial fibrillation (76%) and was similar to the outcome of patients with successful atrial flutter ablation without preexisting atrial fibrillation (25%). CONCLUSION: These data suggest that isthmus ablation with bidirectional block and continuation of amiodarone therapy is an effective therapy for the treatment of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.     

Electrophysiologic studies in atrial flutter

The clinical electrophysiologic approaches to atrial flutter (F) have been activation mapping and the observation of changes induced by programmed stimulation. Sequential endocardial activation mapping has recently yielded information indicating that common F is produced by a large right atrial (RA) reentry circuit, with counterclockwise rotation in the frontal plane, including the inferior vena cava in its center. Functional block in the crista terminalis and conduction slowing in the approaches to the atrioventricular node seem to be important to support reentry. F inscribing positive deflections in the inferior leads usually follows the same path, but in a clockwise direction. Atypical F may be produced by left atrial circuits. Atrial stimulation during F entrains the circuit, resetting it with each stimulus. Collision between antidromic and orthodromic activation during entrainment produces fusion that can be identified in the surface electrocardiogram. The last paced activation restarts F, unless circuit penetration has been enough to modify it by block or disorganization. Entrainment may result in F acceleration, with changes in activation sequence, suggesting a different type of reentry, possibly based on functional factors.     

Entrainment mapping of dual-loop macroreentry in common atrial flutter: new insights into the atrial flutter circuit

INTRODUCTION: The aim of this study was to determine using entrainment mapping whether the reentrant circuit of common type atrial flutter (AFL) is single loop or dual loop. METHODS AND RESULTS: In 12 consecutive patients with counterclockwise (CCW) AFL, entrainment mapping was performed with evaluation of atrial electrograms from the tricuspid annulus (TA) and the posterior right atrial (RA) area. We hypothesized that a dual-loop reentry could be surmised from "paradoxical delayed capture" of the proximal part of the circuit having a longer interval from the stimulus to the captured beat compared with the distal part of the circuit. In 6 of 12 patients with CCW AFL, during entrainment from the septal side of the posterior blocking line, the interval from the stimulus to the last captured beat was longer at the RA free wall than at the isthmus position. In these six patients with paradoxical delayed capture, flutter cycle length (FCL) was 227 +/- 12 ms and postpacing interval minus FCL was significantly shorter at the posterior blocking line than at the RA free wall (20 +/- 11 ms vs 48 +/- 33 ms, P < 0.05). In two of these patients, early breakthrough occurred at the lateral TA. A posterior block line was confirmed in all six patients in the sinus venosa area by intracardiac echocardiography. CONCLUSION: Half of the patients with common type AFL had a dual-loop macroreentrant circuit consisting of an anterior loop (circuit around the TA) and a posterior loop (circuit around the inferior vena cava and the posterior blocking line).     

Randomized comparison of anatomic and electrogram mapping approaches to ablation of typical atrial flutter

INTRODUCTION: The cavotricuspid isthmus can be ablated using an anatomic approach or an electrogram mapping approach in which sites at which there is a gap in the line of block are targeted. The aim of this study was to compare the anatomic and electrogram mapping approaches for creating a line of block in the cavotricuspid isthmus after an initial, unsuccessful anatomically directed ablation line. METHODS AND RESULTS: The subjects of this study were 63 patients with isthmus-dependent atrial flutter in whom a single series of contiguous applications of radiofrequency energy guided by fluoroscopy in the cavotricuspid isthmus did not result in complete block. The patients were randomly assigned to additional ablation on an anatomic basis (n = 31) or guided by single potentials or narrowly split double potentials during coronary sinus pacing (n = 32). After every 15 applications of radiofrequency energy, the alternate approach was used until complete block was achieved. Before cross-over, complete block was achieved in 6 patients (19%) with the anatomic approach compared with 19 patients (59%) with the electrogram mapping approach (P < 0.005). The electrogram mapping approach also was more effective than the anatomic approach in achieving complete isthmus block after the first cross-over (72% vs 23%, P < 0.005) and after the second cross-over (80% vs 42%, P < 0.05). CONCLUSION: When there is incomplete block after an initial series of applications of radiofrequency energy in the cavotricuspid isthmus, complete block is achieved more efficiently with an electrogram mapping approach than with an anatomic approach.     

Effect of chronic amiodarone therapy on excitable gap during typical human atrial flutter

INTRODUCTION: Class I antiarrhythmic drugs increase duration of the excitable gap (EG) during typical atrial flutter whereas intravenous class III drugs decrease the EG. The effect of chronic oral amiodarone therapy on the EG is unknown. METHODS AND RESULTS: EG was prospectively determined by introducing a premature stimulus and analyzing the response pattern during typical atrial flutter in 30 patients without antiarrhythmic drugs and in 20 patients under chronic oral amiodarone therapy. EG was calculated by the difference between the longest coupling interval leading to resetting and the effective atrial refractory period (EARP). A fully EG was defined by the portion of EG where the response curve of the return cycles was flat. A partially EG was defined by the portion of EG where the return cycle increases while coupling interval decreases. A resetting response curve was constructed by plotting the duration of the return cycle against the value of the coupling interval. Cycle length (CL; 222 +/- 17 vs 267 +/- 20 msec, P < 0.0001), EARP (128 +/- 16 vs 152 +/- 18 msec, P < 0.0001), and EG (54 +/- 19 vs 70 +/- 21 msec, P = 0.01) were significantly longer in patients taking amiodarone than in controls. Compared to CL, the relative part of the EARP (57 +/- 7 vs 57 +/- 6%, P = 0.96) and EG (24 +/- 7 vs 26 +/- 8%, P = 0.41) were comparable in both groups. The fully EG was larger in patients under chronic amiodarone therapy than in controls (39 +/- 21 vs 26 +/- 20 msec, P = 0.03). Neither duration of the partially EG (28 +/- 15 vs 31 +/- 15 msec, P = 0.42) nor slope of the ascending portion of the resetting response curve (1.15 +/- 0.5 vs 1.13 +/- 0.4 msec/msec, P = 0.71) differed between the two groups. CONCLUSION: EG in patients under chronic amiodarone therapy is significantly larger than in controls, mainly because of a longer fully EG. This observation may be explained by opposite effects on conduction velocity and refractoriness.     

Radiofrequency ablation for cure of atrial flutter

Abstract Background: Atrial flutter is a common arrhythmia which frequently recurs after cardioversion and is relatively difficult to control with antiarrhythmic agents.
Aims: To evaluate the success rate, recurrence rate and safety of radiofrequency (RF) ablation for atrial flutter in a consecutive series of patients with drug refractory chronic or paroxysmal forms of the arrhythmia.
Methods: Electrophysiologic evaluation of atrial flutter included activation mapping with a 20 electrode halo cadieter placed around the tricuspid annulus and entrainment mapping from within the low right atrial isthmus. After confirmation of the arrhythmia mechanism with these techniques, an anatomic approach was used to create a linear lesion between the inferior tricuspid annulus and the eustachian ridge at the anterior margin of the inferior vena cava. In order to demonstrate successful ablation, mapping techniques were employed to show that bi-directional conduction block was present in the low right atrial isthmus.
Results: Successful ablation was achieved in 26/27 patients (96%). In one patient with a grossly enlarged right atrium, isthmus block could not be achieved. Of the 26 patients with successful ablation, mere has been one recurrence of typical flutter (4%) during a mean follow-up period of 5.5±2.7 months. This patient underwent a successful repeat ablation procedure. Of eight patients with documented clinical atrial fibrillation (in addition to atrial flutter) prior to the procedure, five continued to have atrial fibrillation following the ablation. There were no procedural complications and all patients had normal AV conduction at the completion of the ablation.
Conclusions: RF ablation is a highly effective and safe procedure for cure of atrial flutter. In patients with chronic or recurrent forms of atrial flutter RF ablation should be considered as a first line therapeutic option.     

峡部依赖性心房扑动对心房颤动发作的影响

目的观察导管射频消融治疗峡部依赖性心房扑动(房扑)对心房颤动(房颤)发作的影响,进一步探讨房扑和房颤的关系。方法86例房扑患者,其体表心电图均提示典型房扑,男性54例、女性32例,年龄50.0±15.6(11～74)岁,病程5.6±6.4(0.1～30)年。将所有患者分成A、B两组,A组为房扑合并房颤患者,共25例;B组为不合并房颤患者,共61例;其中A组同时合并房室结折返性心动过速(AVNRT)3例,房室折返性心动过速(AVRT)4例,阵发性房性心动过速(PAT)10例;B组合并房室结折返性心动过速5例,房室折返性心动过速7例。对峡部依赖性房扑者,线性消融下腔静脉—三尖瓣环峡部致双向传导阻滞;房室折返性心动过速者行旁道消融术;房室结折返性心动过速者行慢径改良术,阵发性房速术中持续或可诱发,予以射频消融。平均随访27.1±14.1(6～63)月。结果A组25例患者中,术后68%(17/25)患者不再发作房颤;其余8例仍有房颤发作,其中1例为术前同时合并房室折返性心动过速,5例为合并阵发性房速。61例术前不合并房颤者,术后随访中有16.4%(10/61)新发房颤。86例患者中,6例因病态窦房结综合征行起搏器植入术,随访未诉心悸、胸闷,心电图为窦性心律与起搏心律交替出现。结论房扑可能与房颤具有共同的发生基质,也可以是房颤的触发因素,成功消融房扑后可以阻止房颤的发生。但房颤发生机制多样,消融峡部依赖性房扑,仍会发生房颤,术前合并房颤或房速者是最强的预测因子。     

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.     

Atrial tachycardia masquerading as atrial flutter following ablation of the subeustachian isthmus

We report a case of atrial tachycardia masquerading as atrial flutter in a man who had previously undergone catheter ablation for atrial flutter. The recurrent arrhythmia was electrocardiographically almost identical to the prior atrial flutter; at repeat electrophysiologic study, although bidirectional conduction block was observed in the tricuspid annulus-inferior vena caval isthmus, the atrial arrhythmia was readily initiated. Activation mapping suggested typical atrial flutter, but entrainment techniques demonstrated intra-atrial reentry not involving the ablated isthmus. This case illustrates the need to apply entrainment techniques even in cases of apparent "typical" atrial flutter to confirm that putative ablation targets are necessary for tachycardia perpetuation.     

Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter: refining the continuous line

Ablation of the cavotricuspid isthmus has become first-line therapy for "isthmus-dependent" atrial flutter. The goal of ablation is to produce bidirectional cavotricuspid isthmus block. Traditionally, this has been obtained by creation of a complete ablation line across the isthmus from the ventricular end to the inferior vena cava. This article describes an alternative method used in our laboratory. There is substantial evidence that conduction across the isthmus occurs preferentially over discrete separate bundles of tissue. Consequently, voltage-guided ablation targeting only these bundles with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages in our hands has resulted in reduction of ablation time and fewer recurrences.     

Use of double-potential barrier to identify functional isthmus at the cavotricuspid isthmus for facilitating catheter ablation of isthmus-dependent atrial flutter

INTRODUCTION: The aim of the study was to identify an alternative target for more effective radiofrequency catheter ablation (RFCA) of isthmus-dependent atrial flutter (AFL). METHODS AND RESULTS: We hypothesized that a functional isthmus formed by preexisting double potential barrier at the cavotricuspid isthmus (CTI) could serve as a new target site for facilitating RFCA of AFL. Forty-three consecutive patients with recurrent isthmus-dependent AFL were studied using three-dimensional navigated magnetic mapping and ablation technique. Twenty patients (47%, group A) were shown to have a narrower functional channel at the CTI (functional isthmus). The remaining 23 patients did not have this feature (53%, group B). In group A, double potentials were clustered near the border of the inferior vena cava (IVC) of the CTI and served as a functional channel along the tricuspid annulus (TA). The interspike interval of double potentials was 87 +/- 26 ms near the IVC border and 45 +/- 17 ms (P < 0.0001) near the TA border of CTI. RFCA targeting at the functional isthmus in group A resulted in interruption of bidirectional transisthmus conduction with fewer radiofrequency pulses (6.7 +/- 4.7 in group A vs 21.1 +/- 17.1 pulses in group B, P < 0.001), shorter ablation line (11.6 +/- 4.0 mm vs 37.8 +/- 7.2 mm, P < 0.0001) with no arrhythmia recurrence. These functional isthmuses were found to be located at the lateral third of CTI in 12 patients, middle third in 7, and medial third in 1. This finding is different from that obtained by the conventional method in group B (lateral in 5, middle in 16, medial in 2, P < 0.038). CONCLUSION: In our study, a functional, rather than anatomic, isthmus formed by preexisting double-potential barrier at the CTI was identified in 47% of patients with isthmus-dependent AFL. It is a useful guide to facilitate RFCA of isthmus-dependent AFL.     

射频消融治疗老年房扑房颤患者疗效及安全性的评价

目的展望射频消融治疗老年房扑房颤患者的前景，评价其安全性及疗效。方法回顾3年来在北京大学第一医院进行射频消融的年龄在60～82岁的房扑房颤患者的病例。结果46名患者中1例因不能耐受未能继续消融治疗；20例房扑患者全部消融成功，成功率100％，随访1～30个月无复发；25例房颤患者消融肺静脉78条，以肺静脉电位消失为标准，成功率96％，随访1～30个月，5例复发，成功率80．0％。5例复发患者药物控制心室率；1例出现急性心脏压塞，治疗后好转。将该组并发症的发生率与同期在北京大学第一医院因阵发性室上性心动过速行射频消融的年龄16～60岁组并发症的发生率进行比较，差异无显著性。结论射频消融因其安全性、有效性，对老年患者可明显减少药物副作用，提高生活质量，可成为无禁忌房扑房颤患者的一线治疗方案。     

Ventricular tachycardia as a complication of atrial flutter ablation

A 61-year-old woman with dilated cardiomyopathy, who previously underwent successful radiofrequency catheter ablation for atrial flutter, developed monomorphic ventricular tachycardia (VT). The site of VT origin was the inferobasal right ventricle adjacent to the previous atrial isthmus ablation area. The most likely mechanism for the VT was scar-related reentry, the scar being the result of previous radiofrequency lesions in the atrial isthmus. The VT was successfully ablated.     

High-resolution mapping around the crista terminalis during typical atrial flutter: new insights into mechanisms

INTRODUCTION: The aim of this study was to delineate activation patterns around the crista terminalis (CT) using high-resolution noncontact mapping. METHODS AND RESULTS: Twenty-six patients with typical atrial flutter (20 counterclockwise and 6 clockwise) were enrolled in the study. A noncontact mapping system was used to map atrial flutter. There were three activation patterns around the line(s) of block. Type I (n = 6) showed activation around a single complete line of block located in the CT. Type II (n = 17) showed activation around a single incomplete line of block with a conduction gap in the CT. Type III (n = 3) showed activation around double lines of block, one located in the CT and the other located in the sinus venosa region. Simultaneous activation around the tricuspid annulus and through the CT gap could result in double loop reentry (n = 12). After successful ablation of the cavotricuspid isthmus (CTI) in 24 patients, upper loop reentry was still induced in 12 patients with double loop reentry. Subsequent ablation of the CT gap was performed successfully in these 12 patients, and no arrhythmia was inducible thereafter. During the follow-up period of 8.4 +/- 4.1 months, there was no recurrence of atrial flutter in any patient. CONCLUSION: During typical atrial flutter, the CT might be an incomplete barrier. Simultaneous conduction through the CTI and CT gap could result in double loop reentry. Radiofrequency ablation of the CTI and CT gap was effective in eliminating this arrhythmia.     

Electrophysiologic characteristics and ablation of an atypical atrial flutter in the right atrium

Subeustachian isthmus-dependent typical atrial flutter has been well studied. We demonstrate a case with atypical atrial flutter involving only the base of the right atrium around the inferior vena cava. Entrainment pacing and mapping studies documented a distinct circuit traversing the subeustachian isthmus, propagating through the posterobasal right atrium, and skirting the inferior vena cava. Successful radiofrequency ablation of the arrhythmia was accomplished by creating a linear lesion at the subeustachian isthmus. Mapping of the inferior vena cava region and the demonstration of concealed entrainment are essential steps in establishing the mechanism of the atypical atrial flutter.     

LocaLisa catheter navigation reduces fluoroscopy time and dosage in ablation of atrial flutter: a prospective randomized study

INTRODUCTION: Catheter ablation has become a well-established therapy for isthmus-dependent right atrial flutter (AFL). Recently, mapping and ablation of AFL have been performed using sophisticated three-dimensional mapping systems, such as electroanatomic and noncontact mapping systems. The LocaLisa system enables nonfluoroscopic navigation of intracardiac electrode catheters based on impedance changes related to catheter movements in transthoracic current fields. The aim of this randomized prospective study was to compare the efficacy of the LocaLisa system with the conventional mapping/ablation approach for radiofrequency ablation of AFL. METHODS AND RESULTS: Fifty consecutive patients with AFL (39 men and 11 women; age 65 +/- 10 years) were studied. The patients were randomly assigned to undergo radiofrequency ablation guided by a conventional fluoroscopy-based approach (24 patients) or by the LocaLisa system (26 patients). Ablation success rate and documentation of bidirectional isthmus block were 100% in both groups. Compared with fluoroscopy-guided approaches, LocaLisa-guided procedures demonstrated a reduction in total fluoroscopy time from 15.9 +/- 10.6 minutes to 7.5 +/- 6.5 minutes (P < 0.005). Total fluoroscopy dosage was reduced from 21.0 +/- 19.8 to 8.7 +/- 9.5 Gycm2 (P < 0.05). Fluoroscopy time required for ablation was significantly shortened in the LocaLisa group (2.6 +/- 2.6 min) compared with the conventional approach group (11 +/- 10 min, P < 0.0005). In 9 (35%) of 26 patients, the ablation could be performed with a fluoroscopy time < or = 1 minute. There were no significant differences with regard to the number of radiofrequency applications, fluoroscopy time needed for diagnostic reasons, total procedure time, or other ablation data. CONCLUSION: Compared with the conventional approach, the LocaLisa system significantly reduces the fluoroscopy times needed for ablation of typical AFL.     

Maximum electrogram-guided ablation of cavotricuspid isthmus-dependent atrial flutter

Aims

To verify and re-emphasise the efficacy of the max electrogram-guided approach for ablation of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL).

Methods

Consecutive patients were alternatively assigned to receive either conventional linear radio-frequency (RF) ablation between the tricuspid annulus and inferior vena cava (the linear approach) or RF ablation at sites with the highest electrograms (the max electrogram-guided approach). Sustained, bi-directional CTI block was the endpoint. Procedure parameters and follow-up data were obtained.

Results

In total, 80 patients were included, 40 each for the linear approach and the max electrogram-guided approach. To achieve sustained bi-directional CTI block, the linear approach needed 841 ± 594 sec or 14.0 ± 9.9 RF applications, with total fluoroscopy time of 18.6 ± 9.4 min and total procedure time of 152 ± 58 min, as compared to the max electrogram-guided approach which needed 350 ± 319 sec (p < 0.0001) or 5.8 ± 5.3 RF applications (p < 0.0001), with total fluoroscopy time of 14.8 ± 6.0 min (p < 0.05) and total procedure time of 111 ± 36 min (p < 0.0005). The CTI block was obtained with 3 or less RF applications in 18 patients in the max electrogram-guided group (45%), but only in 2 patients in the linear ablation group (5%). During follow-up of 28 ± 14 months, recurrence cases were 2 in the linear and 1 in the max electrogram-guided group (NS).

Conclusion

During ablation of AFL, directly targeting muscle bundles in the CTI as guided by the highest electrograms is more efficient than making a linear lesion across the entire CTI, since using the former approach needed less RF application, shorter fluoroscopy and procedure times than using the latter. The max electrogram-guided approach may be recommended for routine clinical use to replace the conventional linear ablation approach.