Electrophysiological characteristics and radiofrequency ablation of focal atrial tachycardia originating from the superior vena cava.

The initiation of focal atrial tachycardia (AT) from the superior vena cava (SVC) remains unclear. In 3 patients (2 females, 1 male; aged 57, 66 and 50 years, respectively) with focal AT arising from different parts of the SVC, the AT occurred spontaneously, rather than being induced by electrical stimulation. The cycle length of the tachycardia was highly variable, ranging between 190 and 300 ms in patient 1, 180 and 320ms in patient 2, and 200 and 300ms in patient 3. The clinical or associated arrhythmias were atrial fibrillation (AF) (patients 1, 3) and atrial flutter (AFL) (patients 2, 3). A presumed SVC potential that was earlier than the activation of all the other mapping sites was recorded during AT at the lower anterior (15-mm above the atriocaval junction), the mid-anterior (25-mm above the atriocaval junction) and the lower posterior aspect of the SVC (17-mm above the atriocaval junction. Radiofrequency (RF) ablation targeting the SVC focus with the SVC potential promptly eliminated the focal AT in all 3 patients. The coexistent typical AFL was ablated, but the AF was not. The follow-up period was 6, 6, and 3 months, respectively, for each of the patients under no antiarrhythmic medication; there has not been a recurrence of symptomatic palpitation. In conclusion, focal electrical firing in the SVC can initiate AT and this type of focal AT is always associated with AFL or AF. RF ablation guided by the presumed SVC potential is safe and highly effective in eliminating the tachycardia.     

Two atrial reentrant tachycardias originating from the superior vena cava: Electrophysiological characteristics and radiofrequency ablation

A case with two different types of atrial reentrant tachycardia of superior vena cava (SVC) origin is presented. Recent clinical studies have shown that the origin of focal atrial tachycardia typically lies in the venous structures connecting to both atria—the coronary sinus, the superior and inferior vena cava, and the pulmonary vein. These foci have atrial muscle fiber extensions which have electrophysiological characteristics essential to generation of focal ectopic firing. However, little is known about reentrant mechanism of these venous structures. In this report, we present a case of two atrial tachycardias (SVT1 and SVT2) independently originating from the SVC. SVT1 had 430 ms of tachycardia cycle length, and SVT2 had 390 ms of tachycardia cycle length. Both of them showed the character of reentry, and their earliest activations were recorded in the SVC. They were successfully eliminated by focal radiofrequency ablation in the SVC.     

心房颤动上腔静脉节段性电隔离方法及安全性评估

目的:分析心房颤动(房颤)上腔静脉节段性电隔离的具体手术方法,并评估其安全性.方法:入选2017年11月至2018年9月期间我院阵发性房颤患者50例,患者常规进行肺静脉隔离后,继续行上腔静脉隔离.消融前进行上腔静脉造影,显示上腔静脉与右心房解剖关系,并在CARTO系统运用PentaRay电极导管进行上腔静脉及右心房三维...     

无心房颤动患者腔静脉电活动特性的研究

目的探讨无心房颤动(AF)患者腔静脉内的电活动及其传导特性。方法选择32例无AF患者,记录腔静脉电位分布和腔静脉与心房的电连接类型,观察右房(RA)及腔静脉起搏时局部电活动特性。结果28例(87.5%)存在上腔静脉(SVC)电位,其电位分布:前侧壁14例、前壁12例、环状2例,其电连接类型:单束状10例(31.3%)、双束状16例(50.0%)、环状2例(6.3%);只有5例(15.6%)存在下腔静脉(IVC)电位,电位分布于前侧壁,3例呈单束状、2例呈双束状电连接。RA起搏时RA-SVC的有效不应期(ERP)为202±21ms,SVC起搏时SVC-RA的ERP为228±15ms,两者比较差异有显著性(P<0.05);RA起搏时RA-IVC的ERP为190~230ms(中位数M=195ms),IVC起搏时仅1例患者存在IVC-RA传导,其ERP为200ms。结论无AF患者腔静脉存在电位,其与右房表现为单束状、双束状或环状电连接。     

Impact of Systematic Isolation of Superior Vena Cava in Addition to Pulmonary Vein Antrum Isolation on the Outcome of Paroxysmal, Persistent, and Permanent Atrial Fibrillation Ablation: Results from a Randomized Study

Impact of the Systematic Isolation of the Superior Vena Cava.   Background: Pulmonary veins (PVs) have been shown to represent the most frequent sites of ectopic beats initiating paroxysmal atrial fibrillation (AF). However, additional non-PV triggers, arising from different areas, have been reported as well. One of the most common non-PV sites described is the superior vena cava.
Aims: The purpose of the study was to investigate the impact resulting from the systematic isolation of the superior vena cava (SVCI) in addition to pulmonary vein antrum isolation (PVAI) on the outcome of paroxysmal, persistent, and permanent AF ablation.
Methods: A total of 320 consecutive patients who had been referred to our center in order to undergo a first attempt of AF ablation were randomized into 2 groups. Group I (160 patients) underwent PVAI only; Group II (160 patients) underwent PVAI and SVCI.
Results: AF was paroxysmal in 134 (46%), persistent in 75 (23%), and permanent in 111 (31%) of said patients. SVCI was performed on 134 of the 160 patients (84%) in Group II. SVC isolation was not performed on the remaining 26 patients either because of phrenic nerve capture or the lack of SVC potentials. Comparison of the outcome data between the 2 groups, after a follow-up of 12 months, revealed a significant difference in total procedural success solely with patients manifesting paroxysmal atrial fibrillation (56/73 [77%] Group I vs. 55/61 [90%] Group II; P = 0.04; OR 2.78).
Conclusions: In our study, the strategy of the empiric SVCI in addition to PVAI has improved the outcome of AF ablation solely in patients manifesting paroxysmal AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1–5, January 2010)     

Electrophysiological characteristics and catheter ablation in patients with paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation

Introduction: Paroxysmal supraventricular tachycardia (PSVT) is often associated with paroxysmal atrial fibrillation (AF). However, the relationship between PSVT and AF is still unclear. The aim of this study was to investigate the clinical and electrophysiological characteristics in patients with PSVT and AF, and to demonstrate the origin of the AF before the radiofrequency (RF) ablation of AF.
Methods and Results: Four hundred and two consecutive patients with paroxysmal AF (338 had a pure PV foci and 64 had a non-PV foci) that underwent RF ablation were included. Twenty-one patients (10 females; mean age 47 ± 18 years) with both PSVT and AF were divided into two groups. Group 1 consisted of 14 patients with inducible atrioventricular nodal reentrant tachycardia (AVNRT) and AF. Group 2 consisted of seven patients with Wolff-Parkinson-White (WPW) syndrome and AF. Patients with non-PV foci of AF had a higher incidence of AVNRT than those with PV foci (11% vs. 2%, P = 0.003). Patients with AF and atypical AVNRT had a higher incidence of AF ectopy from the superior vena cava (SVC) than those with AF and typical AVNRT (86% vs. 14%, P = 0.03). Group 1 patients had smaller left atrial (LA) diameter (36 ± 3 vs. 41 ± 3 mm, P = 0.004) and higher incidence of an SVC origin of AF (50% vs. 0%, P = 0.047) than did those in Group 2.
Conclusion: The SVC AF has a close relationship with AVNRT. The effect of atrial vulnerability and remodeling may differ between AVNRT and WPW syndrome.     

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     

Long-term outcome of catheter ablation in patients with atrial fibrillation originating from the superior vena cava

Long‐Term Outcome of SVC AF Ablation. Introduction: Data of the long‐term clinical outcome after superior vena cava (SVC) isolation are limited. We aimed to evaluate the long‐term outcome in patients with atrial fibrillation (AF) who had triggers originating from the SVC and received catheter ablation of AF. Methods and Results: The study consisted of 68 patients (age 56 ± 12 years old, 32 males) who underwent the ablation procedure for drug‐refractory, symptomatic paroxysmal AF originating from the SVC since 1999. Group 1 consisted of 37 patients with AF initiated from the SVC only, and group 2 consisted of 31 patients with both SVC and pulmonary vein (PV) triggers. During a follow‐up period of 88 ± 50 months, the AF recurrence rate was 35.3% after a single procedure. The freedom‐from‐AF rates were 85.3% at 1 year and 73.3% at 5 years. In the baseline study, group 2 had larger left atrium (38 ± 4 mm vs 36 ± 5 mm, P = 0.04), left ventricle (50 ± 5 mm vs 46 ± 5 mm, P = 0.003), and PV diameters. Kaplan–Meier survival analysis showed a higher AF recurrence rate in group 2 compared to that in group 1 (P = 0.012). The independent predictor of an AF recurrence was a larger SVC diameter (P = 0.02, HR 1.4, 95% CI 1.1–1.8). Conclusion: Among the patients with paroxysmal AF originating from the SVC, 73% remained free of AF for 5 years after a single catheter ablation procedure. Superior vena cava isolation without PV isolation is an acceptable therapeutic strategy in those patients with AF originating from the SVC only. The SVC diameter was an independent predictor of AF recurrence. (J Cardiovasc Electrophysiol, Vol. 23, pp. 955‐961, September 2012)     

上腔静脉与界嵴起源心房颤动的电生理特点和导管消融

目的探讨上腔静脉与界嵴起源心房颤动(简称房颤)的电生理特点和导管消融。方法9例房颤患者,完成环肺静脉电隔离后根据电生理和ECG诊断房颤为上腔静脉与界嵴起源。上腔静脉起源进行上腔静脉电隔离,界嵴起源则局灶消融最早激动点。术后随访ECG和Holter。结果上腔静脉起源7例,其中仅2例可根据体表ECG诊断。腔内电生理均发现上腔静脉起源的快速激动触发或驱动房颤,均行上腔静脉电隔离治疗成功。界嵴上部起源2例,腔内电生理发现局灶激动触发房性早搏或房性心动过速,局灶消融均获成功。1例在隔离上腔静脉时出现一过性窦性停搏。结论少数房颤起源于上腔静脉与界嵴的异位灶,腔内电生理具有特征性,上腔静脉电隔离和局灶消融可以有效治疗此类房颤。     

Electrical isolation of the superior vena cava: an adjunctive strategy to pulmonary vein antrum isolation improving the outcome of AF ablation

PV isolation at the antrum (PVAI) has improved safety and efficacy of ablation procedures for atrial fibrillation (AF). AF triggers from the superior vena cava (SVC) may compromise the outcome of PVAI.
Purpose: We evaluated the (1) incidence of SVC triggers, (2) feasibility of empiric SVC electrical isolation (SVCI) as an adjunct to PVAI, and (3) SVCI safety.
Methods and Results: Of 190  patients (group I), 24 (12%) showed SVC triggers. Following PVAI, seven patients had AT originating from the SVC and three had AF. After SVCI, all 24  patients were arrhythmia-free 450 ± 180  days post procedure. In the subsequent 217  patients (group II), empirical SVCI was performed following PVAI. Sixty-six of all 407  patients (16%) experienced recurrence of AF.  A repeat procedure in 25 of the 66  patients showed that five (20%) had AF recurrence initiated by SVC triggers, of whom four were among group I patients (4/190; 2%) and one was from group II (1/217; 0.4%), (P < 0.05). Transient diaphragmatic paralysis can be avoided by pacing at the lateral aspect of the SVC using high output (30  mA). There was no SVC stenosis on CT scans before or 3 months after the procedure. There was no sinus node injury.
Conclusions: The SVC harbors the majority of non-PV triggers of AF. SVCI is feasible, safe, and may be considered as an adjunctive strategy to PVAI for ablation of AF. The long-term favorable outcome of this hybrid approach remains to be evaluated in a larger series of patients.     

Characteristics and outcome in patients receiving multiple (more than two) catheter ablation procedures for paroxysmal atrial fibrillation

Background: The features of multiple catheter ablation procedures for paroxysmal atrial fibrillation (AF) are unknown. We aimed to investigate the electrophysiologic characteristics and the clinical outcomes in the patients with AF who received more than two ablation procedures.
Methods: The study consisted of 15 consecutive patients (age 48 ± 14 years, 10 males) who had undergone three to five (3.3 ± 0.6) catheter ablation procedures for recurrent paroxysmal AF.
Results: Ten patients had pulmonary vein (PV)-AF and one had AF originating from both PVs and the superior vena cava (SVC) in the first ablation procedure. All of them exhibited PV reconnection during the recurrent episodes. Four of the 15 patients had AF originating from non-PV foci (three from the SVC, one from the crista terminalis) in the first procedure, and two had AF recurrences due to recovered conduction from the SVC. In all patients with PV-AF recurrences, repeated PV isolation procedures could effectively eliminate the AF. The incidence of the need for additional LA linear ablation lesions was higher comparing between the first procedure and in the following ablation procedures (18% vs. 71%, P = 0.02). During a follow-up of 1.7 ± 1.1 years, 73% of the patients remained in sinus rhythm without any antiarrhythmic drugs after the final procedure.
Conclusions: Recovered PV connection was the major cause of the AF recurrences despite undergoing multiple catheter ablation procedures. It is advisable to inspect all PVs during the AF recurrence. Repeated PV isolation plus left atrial linear ablations could effectively eliminate the AF with satisfactory outcomes.     

The prognostic significance of exercise-induced atrial arrhythmias

OBJECTIVES: The purpose of the study was to determine if atrial ectopy (AE) or atrial arrhythmias during exercise are predictive of an increased risk of cardiac events and death. BACKGROUND: Although stress-induced atrial arrhythmias are common during exercise testing, there is a paucity of data regarding the correlation with underlying heart disease and cardiovascular outcomes. Atrial arrhythmias may reflect underlying left atrial enlargement and diastolic dysfunction, which are prognostic of mortality. We hypothesized that these stress-induced arrhythmias are associated with long-term adverse cardiac events. METHODS: Exercise echocardiography was performed in 5,375 patients (age 61 +/- 12 years) with known or suspected coronary artery disease. An abnormal result was defined as exercise-induced atrial fibrillation (AF)/atrial flutter, supraventricular tachycardia (SVT), or AE. RESULTS: A total of 311 (5.8%) patients died (132 [2.5%] from cardiac causes) over a period of 3.1 +/- 1.7 years. In addition, 193 (3.6%) patients experienced a myocardial infarction (MI) and 531 (9.9%) patients required revascularization. During exercise testing, 1,272 (24%) patients developed AE, 185 (3.4%) developed SVT, and 43 (0.8%) developed AF. The five-year cardiac death rate was not statistically different between groups (none [3.8%], AE [4.3%], SVT [3.7%], AF [0%], p = 0.43). The five-year rate of MI was significantly different between groups (none [5.7%], AE [8.3%], SVT [0%], AF [9.0%], p = 0.005). The five-year rate of revascularization between groups was not significantly different (none [14.2%], AE [17.0%], SVT [11.8%], AF [14.8%], p = 0.50). A composite of all five-year adverse end points was similar between groups (none [22.7%], AE [27.8%], SVT [17.7%], AF [25.7%], p = 0.10). In stepwise multivariate analysis, AE was not predictive of myocardial infarction when taking into account traditional clinical variables and exercise test results. CONCLUSIONS: In this large cohort of patients, the occurrence of AE was predictive of an increased risk of MI. However, the association did not persist after adjustment for clinical and exercise variables known to predict adverse long-term cardiovascular outcomes. The rate of long-term cardiac death or revascularization was not influenced by the development of stress-induced atrial arrhythmias.     

A Focal Source of Atrial Fibrillation in the Superior Vena Cava: Isolation and Elimination by Radiofrequency Ablation with the Guide of Basket Catheter Mapping

Although it has been reported that pulmonary veins sometimes act as a focal driver of atrial fibrillation (AF), little has been reported concerning the contribution of the superior vena cava (SVC) to the maintenance of AF. Here we report a patient with sustained AF due to focal discharges inside the SVC after pulmonary vein isolation procedure. Stepwise radiofrequency current applications with the guide of multielectrode basket catheter mapping first disconnected the arrhythmogenic SVC from the right atrium and then eliminated the tachycardia.     

Characterization of right atrial substrate in patients with supraventricular tachyarrhythmias

Right atrial substrate of supraventricular tachyarrhythmias. BACKGROUND: Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT). METHODS AND RESULTS: Forty patients (aged 55+/-20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (-1.34+/-0.22 vs. -0.90+/-0.40 vs. -1.00+/-0.36 vs. -0.85+/-0.35 mV, P=0.04), atrial pacing at cycle lengths of 500 ms (-1.30+/-0.29 vs. -0.70+/-0.35 vs. -0.76+/-0.25 vs. -0.64+/-0.26 mV, P=0.02), and 300 ms (-1.54+/-0.47 vs. -0.94+/-0.21 vs. -0.75+/-0.27 vs. -0.57+/-0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF. CONCLUSION: Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.     

递进式消融法治疗持续性心房颤动的初步体会

目的评价一种递进式消融法治疗持续性心房颤动（房颤）的疗效。方法34例持续性房颤患者,年龄（54．8±11．4）岁,病程（36．5±9．8）个月。按以下顺序进行递进式消融：环肺静脉前庭消融达肺静脉电学隔离,左心房顶部和二尖瓣环峡部线性消融,心房碎裂电位消融,针对房颤转变的心房扑动（房扑）／房性心动过速（房速）行Carto激动标测结合拖带技术以明确其机制,并力求通过消融终止。结果递进式消融法使88．2％患者房颤节律发生变化（直接终止或转变为房扑／房速）,61．8％直接通过消融恢复窦性心律。随访（12．6±6．2）个月,82．4％患者维持窦性心律（其中42．9％服用胺碘酮）。结论递进式消融是治疗持续性房颤的一种有效方案。     

典型心房扑动对心房颤动导管消融复发的影响

目的 评价典型心房扑动(房扑)对心房颤动(房颤)导管消融复发的影响.方法 120例药物治疗无效的阵发性房颤患者在三维电解剖标测系统和肺静脉环状标测电极导管联合指导下行环肺静脉电隔离.其中17例(14.2%)合并典型房扑(房扑组,其余作为对照组),行三尖瓣环峡部消融,三尖瓣环峡部消融终点为三尖瓣环峡部双向阻滞.房颤复发定义为导管消融3个月后发生房性快速心律失常.结果 房扑组房颤病程(9.8±10.7)年,长于对照组(5.9±6.3)年,差异有统计学意义(P=0.036).房扑组与对照组相比,年龄、性别、合并器质性心脏病、左心房直径、左心室射血分数差异无统计学意义.随访91～401(237±79)d,房扑组房颤复发率为47.1%,对照组房颤复发率为12.6%,两组间差异有统计学意义(P=0.001).经校正年龄、房颤病程、合并器质性心脏病、左心房直径等因素,Cox多因素分析发现消融术前合并房扑是房颤复发的独立危险因素(危险比3.52,95%可信区间1.32～9.34,P=0.012).结论 典型房扑可能增加房颤导管消融术后房颤的复发,房颤导管消融前应对患者是否合并典型房扑进行认真评价.     

Quantifying intracardiac organization of atrial arrhythmias using temporospatial phase of the electrocardiogram

INTRODUCTION: Separating nonisthmus-dependent atrial flutter (AFL) from "organized" atrial fibrillation (AF), or isthmus-dependent AFL, may be difficult using ECG characteristics alone. We hypothesized that temporal and spatial phase analysis of ECG atrial waveforms could effectively separate these rhythms by quantifying subtle variations in ECG atrial activation during supraventricular tachycardias (SVT). METHODS AND RESULTS: We studied 52 patients at electrophysiologic study (EPS) who demonstrated isthmus-dependent (n = 15) and nonisthmus-dependent (n = 9) AFL, atrial tachycardia (n = 6), AV nodal reentry (n = 9), orthodromic reciprocating tachycardia (n = 6), and AF (n = 7). Atrial activity was represented as a series of correlations of an atrial template to successive time samples of the arrhythmia ECG. Spatial phase was analyzed as a reproducible relationship of this atrial activity between leads over time; temporal regularity was measured from power spectra. Spatial phase was maintained (coherent) in lead planes V5/aVF (XY), V5/V1 (XZ), and aVF/V1 (YZ) in 15 of 15 cases of isthmus-dependent AFL, but in only 1 of 9 cases of nonisthmus-dependent AFL (P < 0.01; chi2). Temporally, all cases of AFL showed one dominant peak on correlation spectra (magnitude >6 dB), suggesting one activation wavefront, although this was smeared in nonisthmus-dependent cases. In contrast, AF showed inconsistent spatial phase in all planes and broad band spectra, consistent with multiple and/or variable activation paths. All other SVTs showed spatial coherence and one dominant spectral peak. CONCLUSION: Coherence of temporal and spatial phase is a powerful approach to measure the spatial organization of intracardiac activation from the ECG that reveals a spectrum from SVT to isthmus-dependent and nonisthmus-dependent AFL, to AF.     

上腔静脉起源房性心律失常的电生理特征及导管消融治疗效果

目的 探讨上腔静脉（SVC）起源房性心律失常的导管消融策略。方法 经心内电生理检查和导管消融证实起源于SVC房性心律失常共14例，在传统或三维标测系统指引下，结合SVC造影确定最早激动点或起源部位，局灶性消融或节段性/环状消融电隔离SVC。结果 5例房性心动过速（AT）在SVC内标测到最早激动点，局灶性消融成功；9例SVC起源房性早搏（PAC）伴发心房颤动(AF)患者经节段性或环状消融电隔离SVC成功。3例术中SVC电隔离后出现SVC自律电活动。结论 SVC起源房性心律失常有特征性的心内电生理特点，消融时应注意识别AT或PAC。可通过局灶性或阶段性/环形电隔离SVC消融成功。     

Electrical connection between the right atrium and the superior vena cava,and the extent of myocardial sleeve in a patient with atrial fibrillation originating from the superior vena cava

We describe a case in which the superior vena cava (SVC) was electrically isolated by an application of radiofrequency energy to a point with electrical connection between the right atrium and the SVC in a patient with atrial fibrillation (AF) originating from the SVC. The connection was located in the posteroseptal region between the right atrium and the myocardial sleeve extending into the SVC. Local AF occurred after radiofrequency ablation and rapid activities were recorded all around the SVC, whereas the atrium was still in sinus rhythm. It is suggested that focal AF in the SVC contributes not only to the initiation but also to the maintenance of AF, and the myocardial sleeve extends into the SVC through a connection point to cover the entire internal lumen.     

Effect of right atrial isthmus ablation on the occurrence of atrial fibrillation: observations in four patient groups having type I atrial flutter with or without associated atrial fibrillation

BACKGROUND: The goal of this study was to test the hypothesis that the occurrence of atrial fibrillation (AF), in at least some patients with coexisting type I atrial flutter (AFL), is based on macro-reentry around the tricuspid valve orifice, including the right atrial (RA) isthmus, by evaluation of AF recurrences after successful ablation of AFL. METHODS AND RESULTS: Eighty-two consecutive patients with type I AFL, with or without concomitant AF, underwent radiofrequency ablation (RFA) of the RA isthmus by an anatomical approach. The results were analyzed in 4 groups of patients: group 1 (only AFL; 29 patients), group 2 (AFL >AF; 22 patients), group 3 (AF >AFL; 15 patients), and group 4 (developing AFL while receiving class IC antiarrhythmic drug therapy for AF, the "class IC atrial flutter"; 16 patients). In all groups, RFA of type I AFL was performed with a high (>/=93%) procedural success rate. In group 1, only 2 patients (8%) had AF after (18+/-14 months) AFL ablation. These figures were 38% (20+/-14 months) and 86% (13+/-8 months) in groups 2 and 3, respectively. Group 4 patients (4+/-2 months) had a 73% freedom of AF recurrences with continuation of the class IC agent. CONCLUSIONS: The low incidence of new AF during long-term follow-up after RFA of type I AFL makes it unlikely that radiofrequency lesions promote the development of AF. The impact of isthmus ablation on AF recurrences differs according to the clinically predominant atrial arrhythmia and suggests a possible role of the RA isthmus in the occurrence of AF in some patients. Ablation of class IC atrial flutter in patients with therapy-resistant AF is a novel approach to management of this patient subset. Careful classification of AF patients plays a role in the selection of the site of ablation therapy.