阵发性心房颤动发作特点的研究

目的：分析阵发性心房颤动（房颤）的发作特点。方法：42例阵发性房颤患者分成有器质性心脏病和无可发现的器质性心脏病2例,共进行45次24h动态心电图检查,对比房颤发作前30min和1min的窦性心室率,以及诱发和不诱发房颤的房性早搏的配对间期（PP′）和早搏指数（PI）。结果：随机抽取53例次的阵发性房颤样本。房颤发作前30min和1min的平均窦性心室率改变不显著。但14例次（33％）和15例次（36％）房颤发作前1min的窦性心室率＜60次／min,与53个不诱发房颤的房性早搏相比。48个诱发房颤的房性早搏的PP′间期和PI均显著缩短（P＜0．001）。有器质性心脏病和无器质性心脏病的2组阵发性房颤患者的各项观察指标差异均显著性。结论：短配对间期的房性早搏是阵发性房颤的独立诱发因素,部分患者的房颤发作与心动过缓有关,采取相应的治疗措可能预防房颤的发生。     

风心病慢性房颤心外膜标测心房有效不应期的对比研究

目的:研究风心病慢性房颤的电生理特征。方法:对29例风心病伴或不伴慢性房颤的病人在行二尖瓣置换术时,采用心外膜标测技术测定左、右心房各部位的有效不应期(AERP)及右房内和房间的传导时间。结果:风心病慢性房颤组左、右心房AERP比窦性心律明显缩短(P<0.05),左、右心房各部分的AERF,之间有明显差异(P< 0.01),即存在明显离散性;慢性房颤组的右房和房间传导时间在转复为窦性心律和缩短刺激右房高位问期时均显著长于正常对照组(P<0.05)。结论:风心病慢性房颤心房各部位AERP的差异反映了其AERP的离散性,而AERP 的离散性在房颤的诱发和维持过程中起着重要作用。     

房性早搏始动的阵发性心房颤动的动态心电图分析

了解房性早搏 (简称早搏 )与阵发性心房颤动 (简称房颤 )的关系。通过 2 4h动态心电图分析 2 4例阵发性房颤患者 ,观察其 2 4h房颤的发作阵数 ,房早的发作情况 ,诱发和未诱发房颤的房早的联律间期、房早前周长、房早前12 0s房早频率等。结果 :诱发房颤的房早比未诱发房颤的房早显著提前 (35 5 .9± 32 .8msvs 4 0 8.4± 4 1.7ms,P <0 .0 1) ,房早是否诱发房颤还与房早前周长长 (85 4± 10 6msvs 74 2± 113ms ,P <0 .0 1)及房早前 12 0s的房早频率快 (2 1.7± 15 .3次 /分vs9.79± 7.92次 /分 ,P <0 .0 1)有关。结论 :房早是否始动阵发性房颤不仅与房早的联律间期有关 ,而且与房早前周长及其前 12 0s房早的频率有关。     

阵发性心房颤动患者心房及肺静脉不应期离散度的变化

目的探讨阵发性房颤患者房颤相关组织的电生理特性改变情况。方法选取阵发性房颤患者10例(房颤组)和无房颤病史的左侧旁路有显性预激波患者15例(对照组)。将大头电极分别放置在两组患者左上肺静脉、左下肺静脉、右上肺静脉、右下肺静脉开口及左心房顶壁、前壁、后壁、高位右心房,分别测定各部位有效不应期(EPR)。结果①房颤组心房及肺静脉EPR离散度指数(DI)为0.117±0.028,对照组为0.074±0.029,两组比较,P<0.05。②房颤组左心房ERP为(234.00±28.72)ms,肺静脉ERP为(230.75±32.69)ms;对照组左心房ERP为(248.00±25.99)ms,肺静脉ERP为(244.33±26.78)ms,两组比较,P均<0.05。结论阵发性房颤患者DI明显增大,左心房、肺静脉ERP显著缩短。     

Coronary sinus pacing initiates counterclockwise atrial flutter while pacing from the low lateral right atrium initiates clockwise atrial flutter: Analysis of episodes of direct initiation of atrial flutter

Introduction: Rapid atrial pacing in sinus rhythm may directly induce atrial flutter without provoking intervening atrial fibrillation, or initiate atrial flutter indirectly, by a conversion from an episode of transient atrial fibrillation provoked by rapid atrial pacing. The present study was performed to examine whether or not the direct induction of clockwise or counterclockwise atrial flutter was pacing-site (right or left atrium) dependent. Methods and Results: We analyzed the mode of direct induction of atrial flutter by rapid atrial pacing. In 46 patients with a history of atrial flutter, rapid atrial pacing with 3 to 20 stimuli (cycle LENGTH = 500 − 170 ms) was performed in sinus rhythm to induce atrial flutter from 3 atrial sites, including the high right atrium, the low lateral right atrium, and the proximal coronary sinus, while recording multiple intracardiac electrograms of the atria. Direct induction of atrial flutter by rapid atrial pacing was a rare phenomenon and was documented only 22 times in 15 patients: 3, 11, and 8 times during stimulation, respectively, from the high right atrium, low lateral right atrium, and the proximal coronary sinus. Counterclockwise atrial flutter (12 times) was more frequently induced with stimulation from the proximal coronary sinus than from the low lateral right atrium (8 vs 1, P = .0001); clockwise atrial flutter (10 times) was induced exclusively from the low lateral right atrium (P = .0001 for low lateral right atrium vs proximal coronary sinus, P = .011 for low lateral right atrium vs high right atrium). Conclusions: Direct induction of either counterclockwise or clockwise atrial flutter was definitively pacing-site dependent; low lateral right atrial pacing induced clockwise, while proximal coronary sinus pacing induced counterclockwise atrial flutter. Anatomic correlation between the flutter circuit and the atrial pacing site may play an important role in the inducibility of counterclockwise or clockwise atrial flutter.     

The different mechanisms between late and very late recurrences of atrial fibrillation in patients undergoing a repeated catheter ablation

Introduction: The mechanisms of late (<1 year after the ablation) and very late (>1 year after the ablation) recurrences of paroxysmal atrial fibrillation (AF) after catheter ablation have not been reported.
Methods and Results: Fifty consecutive patients undergoing a repeated electrophysiologic study to investigate the recurrence of paroxysmal AF after the first ablation were included. Group 1 consisted of 12 patients with very late (26 ± 13 months) and group 2 consisted of 38 patients with late (3 ± 3 months) recurrence of paroxysmal AF. In the baseline study, group 1 had a lower incidence of AF foci from the pulmonary veins (PVs) (67% vs 92%, P = 0.048) and a higher incidence of AF foci from the right atrium (50% vs 13%, P = 0.014) than group 2. In the repeated study, group 1 had a higher incidence of AF foci from the right atrium (67% vs 3%, P < 0.001) and a lower incidence of AF foci from the left atrium (50% vs 97%, P < 0.001), including a lower incidence of AF foci from the PVs (50% vs 79%, P = 0.07) and from the left atrial free wall (0% vs 29%, P = 0.046) than group 2. Furthermore, most of these AF foci (64% of group 1, 65% of group 2) were from the previously targeted foci.
Conclusion: The right atrial foci played an important role in the very late recurrence of AF, whereas the left atrial foci (the majority were PVs) were the major origin of the late recurrence of AF after the catheter ablation of paroxysmal AF.     

Predicting the arrhythmogenic foci of atrial fibrillation before atrial transseptal procedure: implication for catheter ablation

INTRODUCTION: Use of endocardial atrial activation sequences from recording catheters in the right atrium, His bundle, and coronary sinus to predict the location of initiating foci of atrial fibrillation (AF) before an atrial transseptal procedure has not been reported. The purpose of the present study was to develop an algorithm using endocardial atrial activation sequences to predict the location of initiating foci of AF before transseptal procedure. METHODS AND RESULTS: Seventy-five patients (60 men and 15 women, age 68 +/- 12 years) with frequent episodes of paroxysmal AF were referred for radiofrequency ablation. By retrospective analysis, characteristics of the endocardial atrial activation sequences of right atrial, His-bundle, and coronary sinus catheters from the initial 37 patients were correlated with the location of initiating foci of AF, which were confirmed by successful ablation. The endocardial atrial activation sequences of the other 38 patients were evaluated prospectively to predict the location of initiating foci of AF before transseptal procedure using the algorithm derived from the retrospective analysis. Accuracy of the value <0 msec (obtained by subtracting the time interval between high right atrium and His-bundle atrial activation during atrial premature beats from that obtained during sinus rhythm) for discriminating the superior vena cava or upper portion of the crista terminalis from the pulmonary vein (PV) foci was 100%. When the interval between atrial activation of ostial and distal pairs of the coronary sinus catheter of the atrial premature beats was <0 msec, the accuracy for discriminating left PV foci from right PV foci was 92% in the 24 foci from the left PVs and 100% in the 19 foci from the right PVs. CONCLUSION: Endocardial atrial activation sequences from right atrial, His-bundle, and coronary sinus catheters can accurately predict the location of initiating foci of AF before transseptal procedure. This may facilitate mapping and radiofrequency ablation of paroxysmal AF.     

心房颤动环肺静脉口外线性消融术后二次消融的电生理发现及随访结果

目的介绍三维导航下环肺静脉口外线性消融治疗心房颤动（房颤）术后快速房性心律失常及房颤复发患者二次消融时的电生理发现、消融策略及随访结果。方法2004年4月至2006年5月,采用左心房线性消融治疗房颤共91例。术后4例患者因心动过速反复发作或无休止发作于2周内行二次消融术。随访3个月后,25例患者有快速性心律失常发作,其中15例接受二次消融术。在所有接受二次消融的19例患者中,第一次消融前房颇为阵发性者11例,持续性2例,永久性6例,其中男性17例,女性2例,年龄25～65（53±12）岁。所有患者术中均使用环状电极行肺静脉电位探查。结果5例患者发现窦律下左侧肺静脉延迟电位,1例出现右侧肺静脉延迟电位,2例患者双侧同时出现延迟肺静脉电位;此类患者于环状电极指导下标测原消融线径的传导“缺口”并再次隔离成功。3例患者左侧肺静脉内颤动样节律,递减传导至左心房出现不规则房性心动过速;此类患者再次于三维标测指导下行左侧环状消融隔离成功;1例患者左侧肺静脉心动过速并1：1传导至左心房,经终止心动过速后隔离成功。4例患者肺静脉探查未发现肺静脉电位,但诱发出其他心动过速,包括右房瘢痕性房性心动过速、隐匿性旁路介导的室上性心动过速、右后间隔局灶性房性心动过速及三尖瓣峡部依赖的心房扑动。此4例患者在常规标测和三维标测指导下,心动过速均被成功消融。术中呈房颤节律者3例,再次于三维标测指导下行环肺静脉线性消融获成功。平均随访4～26（11．5±8．5）个月,16例患者无快速性心律失常发作,1例有频繁房性早搏,1例永久性房颤患者仍呈房颤节律,另1例永久性房颤患者转为阵发性房颤。结论肺静脉与左心房之间电传导恢复是消融术后出现快速房性心律失常的主要因素。肺静脉以外的心动过速在左心房线性消融术后可以表现为独立的心动过速,也可以触发房颤;环肺静脉口外线性消融不足以完全改良永久性房颤的维持基质。     

Simultaneous occurrence of atrial fibrillation and atrial flutter

INTRODUCTION: Early reports suggested that some patients with "atrial fibrillation/flutter" might have atrial fibrillation in one atrium and atrial flutter in the other. However, more recent conceptions of atrial fibrillation/flutter postulate that the pattern is due to a relatively organized (type I) form of atrial fibrillation. We report the occurrence and ECG manifestations of simultaneous atrial fibrillation and flutter in patients undergoing attempted catheter ablation of atrial flutter. METHODS AND RESULTS: In patients undergoing radiofrequency ablation for atrial flutter, an attempt was made to entrain atrial flutter by pacing in the right atrium. The arrhythmias observed occurred following attempts at entrainment, or spontaneously in one case. Twelve transient episodes of simultaneous atrial fibrillation and flutter were observed in five patients. The atrial fibrillation was localized to all or a portion of one atrium, during which the other atrium maintained atrial flutter. In each case, the surface 12-lead ECG reflected the right atrial activation pattern. No patients had interatrial or intra-atrial conduction block during sinus rhythm, suggesting functional intra-atrial block as a mechanism for simultaneous atrial fibrillation/flutter. CONCLUSION: In certain patients, the occurrence of transient, simultaneous atrial fibrillation and flutter is possible. In contrast to prior studies in which it was suggested that left atrial or septal activation determines P wave morphology, the results of the present study show that P wave morphology is determined by right atrial activation. Functional interatrial block appears to be a likely mechanism for this phenomenon.     

Bi-atrial mapping of atrial arrhythmias

Cardiac mapping of atrial activation was originally performed in animals during open chest preparations, using epicardial electrodes. The development of endocardial egg-shaped multiple electrodes provided detailed assessment of the minimum number of wavelengths required to sustain atrial fibrillation (AF), as well as the role of interatrial connections during AF. Subsequently, several studies on bi-atrial epicardial high-density mapping in animals and humans also reported on the importance of interatrial connections, as well as the specific characteristics of the left atrium as compared with the right atrium during chronic AF. Endocardial bi-atrial mapping studies using electrode catheters were reported using basket-shaped catheters carrying 64 electrodes. Animal studies suggested that septal activation was asynchronous and discordant, while a human study outlined the multiple origins of atrial ectopic beats following DC cardioversion in patients with chronic atrial fibrillation. The advent of non-fluoroscopic mapping systems significantly changed our approach to percutaneous endocardial mapping. Simultaneous bi-atrial studies using electroanatomic mapping were performed in sinus rhythm as well as in atrial flutter. These studies demonstrated the predominance of interatrial conduction over Bachmann's Bundle and the coronary sinus-left atrial connection during respectively, sinus rhythm and atrial flutter. Simultaneous bi-atrial non-contact mapping was initially performed during porcine studies and later in humans, demonstrating asynchronous and discordant septal activation both during sinus rhythm or left lateral atrial pacing. Preliminary studies from simultaneous bi-atrial non-contact mapping in humans in whom AF occurred spontaneously or was induced suggests three main types of atrial activation, consisting of left atrial drivers causing the right atrium to fibrillate following conduction over interatrial connections, the right atrium independently sustaining AF, even after pulmonary vein disconnection, and both atria fibrillating independently without activation over interatrial connections. Bi-atrial mapping has been essential for our understanding of normal and abnormal atrial activation, and ultimately may provide new approaches for ablation of atrial fibrillation.     

Regional endocardial mapping of spontaneous and induced atrial fibrillation in patients with heart disease and refractory atrial fibrillation.

We performed simultaneous catheter mapping of right and left atrial regions at onset and during sustenance of spontaneous atrial fibrillation (AF) in patients with ischemic and/or hypertensive heart disease. Seventeen patients with structural heart disease had spontaneous and electrically induced AF episodes mapped from their onset simultaneously in multiple right and left atrial regions. Atrial premature complexes (APCs) that initiated spontaneous AF had coupling intervals ranging from 260 to 400 ms (mean 332 +/- 61), most commonly arising from the lateral right atrium (31%), right atrioventricular junction (13%), atrial septum (6%), superior left atrium (25%), or inferior left atrium (25%). APC morphology on surface electrocardiograms did not correlate with origin in specific atrial regions. The earliest regions of atrial activation for the first AF cycle were the lateral right atrium (n = 5), superior left atrium (n = 4), distal or mid coronary sinus (n = 4), atrial septum (n = 2), and right atrioventricular junction at the His bundle location (n = 2). Spontaneous AF at onset usually showed discrete but irregular electrograms at virtually all right and left atrial sites mapped, with a reproducible region of AF initiation in all 8 patients with multiple events. The region of earliest atrial activation at spontaneous AF onset was in close proximity to the APC origin in 15 of 16 patients (94%), and 39 of 40 episodes (97%) mapped. Stable patterns of right and left atrial activation were observed at AF onset in 14 patients. Induced AF elicited with right atrial stimulation demonstrated different sites of earliest regional atrial activation at onset compared with spontaneous AF events in 4 of 8 patients. However, discrete intracardiac electrograms were also present in induced AF in all of the mapped atrial regions. Furthermore, the site of extrastimulus delivery in induced AF was also found to be in close proximity to the earliest region of atrial activation for the first AF beat. We conclude that spontaneous AF is initiated by APCs arising in different right or left atrial regions in patients with structural heart disease and the initial region of atrial activation in AF is in proximity to the region of APC origin. Organized and repetitive electrical activation is frequently observed in both right and left atria at AF onset. Although electrically induced AF may have different activation patterns than spontaneous AF at onset in many patients, both types of AF demonstrate organization and earliest atrial activation in proximity to the initiating APC.     

Progressive remodeling of the atrial substrate--a novel finding from consecutive voltage mapping in patients with recurrence of atrial fibrillation after catheter ablation

Background: Atrial substrate properties have been demonstrated to be related to atrial arrhythmias. This study investigated whether the atrial substrate exhibits progressive remodeling in patients with recurrence of atrial fibrillation (AF) after catheter ablation.
Methods and Results: Fifteen consecutive AF patients (52 ± 12 years old, 12 males) underwent the same mapping technique (NavX, St. Jude Medical, Minnetonka, MN, USA) and same ablation technique for primary AF and recurrence of AF (170 ± 66 days after the first procedure). The bipolar mean peak-to-peak voltage (PPV) of the global left atrium during sinus rhythm significantly decreased in the second procedure (2.25 ± 0.62 vs. 1.79 ± 0.60 mV, P = 0.008). Also, the percentage of the surface area of the low voltage zone (LVZ; less than 0.5 mV) in the left atrium increased from 6 ± 4% to 13 ± 6% (P = 0.001) in the second procedure. There was no significant change in the right atrial bipolar mean PPV or surface area of the LVZ in the second procedure.
Conclusion: Atrial substrate remodeling with a progressive decrease in the left atrial voltage was demonstrated in patients with recurrent AF.     

Intra-operative cooled-tip radiofrequency linear atrial ablation to treat permanent atrial fibrillation.

AIMS: To demonstrate the safety and efficacy of saline irrigated cooled-tip atrial linear endocardial radiofrequency ablation (SICTRA) concomitant to open-heart surgical procedures in the treatment of permanent atrial fibrillation (AF). METHODS AND RESULTS: Two hundred and twenty-two patients presenting with permanent AF and the need for cardiac surgery were included. In addition to the cardio-surgical procedure [mitral valve (MV) surgery (n = 94), aortic valve replacement (n = 29), bypass surgery (n = 76 including 24 patients with additional MV surgery), and combined procedures (n = 23)] concomitant SICTRA was performed. In 116 patients, the ablation pattern was restricted to the left atrium alone. During the mean follow-up of 29 months, 174 patients (78%) converted to sinusrhythm (SR). In patients with SICTRA restricted to the left atrium conversion rates were not different compared to a biatrial approach (83 vs. 74%, P = 0.47). Thirty-days mortality was found to be 4% (9/222). Post-mortem evaluation revealed 23% of all lesions to be histologically non-transmural. In the overall group, only 4% of patients developed sustained secondary regular atrial arrhythmia. CONCLUSIONS: SICTRA safely and effectively restores stable SR in 78% of patients with permanent AF undergoing open-heart surgery. Rhythm outcome is not influenced by treatment of the right atrium. Sustained regular atrial arrhythmia with the need for invasive treatment strategies occurs in 4% although intra-operative ablation lesions are often non-transmural.     

Wavelength and Conduction Inhomogeneity in Each Atrium in Patients with Isolated Mitral Valve Disease and Atrial Fibrillation

INTRODUCTION: Patients with mitral valve disease frequently have atrial fibrillation (AF), and the left atrium is presumed to be the primary atrium that develops AF. However, it is still not clear whether the electrophysiologic abnormalities responsible for AF are confined to the left atrium in this subset of patients. METHODS AND RESULTS: To examine the AF vulnerability of each atrium, we measured the wavelength and inhomogeneity of the conduction at the lateral right atrium, lateral left atrium, and Bachmann's bundle after defibrillation of AF in seven patients undergoing the maze procedure and mitral valve surgery for AF and isolated mitral valve disease, respectively (AF group). The data were compared with five coronary surgery patients in sinus rhythm (SR group). The wavelength in the AF group was significantly shorter (P < 0.05) than in the SR group not only at the lateral left atrium (225 +/- 62 vs 285 +/- 36 mm) but also at the lateral right atrium (214 +/- 54 vs 254 +/- 34 mm). The variation coefficient of the local maximum activation phase difference in the AF group (1.9 +/- 0.8 at the right atrium, 2.1 +/- 0.8 at the lateral left atrium, and 2.0 +/- 0.6 at Bachmann's bundle) was significantly greater (P < 0.05) than in the SR group at all atrial regions. CONCLUSION: AF vulnerability was not confined to the left atrium immediately after defibrillation in AF patients with isolated mitral valve disease. Electrical remodeling resulting from perpetuation of AF, pathological changes extending to the right atrium, geometric changes caused by the atrial interactions occurring across the interatrial septum, or a combination of these may explain the results.     

心房颤动患者经导管射频消融术后不同时期左心房结构及功能的动态变化

目的:观察射频消融术对阵发性和持续性心房颤动(房颤)患者左心房结构和功能不同时期的影响。方法:临床诊断房颤的79名患者作为研究对象(阵发性房颤组65例、持续性房颤组14例),随访1年,行超声心动图检查监测左心房最大面积(左心房左右径×上下径)、左心房最大容积(LAVmax)、左心房最小容积(LAVmin)、左心房P容积(LAVp)等左心房结构指标,并通过左心房被动射血分数(LAPEF),左心房主动射血分数(LAAEF),左心房排空容积等指标探讨左心房功能的变化。体检非房颤人群22例作为对照组。全部数据采用SPSS17.0软件包进行统计学分析。结果:①消融术前检测显示:房颤组左心房最大面积、LAVmax、LAVmin均高于正常对照组(P0.05);并且持续性房颤组左心房增大更显著(P0.05)。房颤组LAAEF低于正常对照组(P0.05),其中持续性房颤组下降更明显(P0.05)。LAPEF及左心房排空容积各组间差异无统计学意义。②两组房颤患者术后左心房最大面积、LAVmax较术前均有变小(P0.05),但两者出现变化的时间点不同,阵发性房颤组在术后1年明显变小(P0.05),持续房颤组在术后近期就出现明显变小(P0.05)。两组LAAEF、LAPEF、排空容积等较术前均无显著性变化。③持续性房颤组左心房最大面积术后近期、中期变化率大于阵发性房颤组(P0.05),但至术后1年变化率两者差异无统计学意义。结论:经导管射频消融术能缩小房颤患者增大的左房结构,近、中期在持续性房颤患者更加显著;经导管射频消融术本身对左心房功能无明显影响。     

持续性心房颤动经导管射频消融治疗的方法探讨(附三例报告)

探讨经导管射频消融治疗持续性心房颤动 (简称房颤 )的可行性。 3例房颤患者房颤持续时间 2个月至 1年4个月。术前口服胺碘酮 ,1例转为窦性心律伴频发房性早搏 (简称房早 ) ,1例转为房早与短阵房颤和阵发心房扑动 (简称房扑 ) ,1例转为房早与阵发房性心动过速 (简称房速 )。经导管作点状消融或点状消融加房扑线性消融 ,2例术中房早消失 ,1例房早显著减少 ,经快速心房刺激或静脉点滴异丙肾上腺素均不能诱发房颤。 1例术后有短阵房颤发作 ,服用莫雷西嗪 ,房颤未再发作。结论 :某些持续性房颤用药物后可转复成窦性心律伴频发房早、房扑或房速 ,局部单点消融或单点消融加线性消融可以达到治疗目的。     

Right atrial modification of maze surgery does not affect refractoriness and conduction patterns of human lone atrial fibrillation.

BACKGROUND: Tissue mass and structure are relevant for initiation and persistence of fibrillation. Modification of the right atrium during maze surgery may change the arrhythmogenic substrate of atrial fibrillation (AF). METHODS AND RESULTS: Epicardial mapping was performed in 9 patients undergoing unmodified maze III surgery for lone paroxysmal AF. Simultaneous recording of AF on the right and left atrium was carried out with two spoon-electrodes each harbouring 64 terminals. Activation maps of AF were made to study AF wavelet organization. The recording position on right and left atria was outside the surgical field and remained unchanged before and after surgery. Before surgery, mean right and left fibrillatory intervals were 174+/-23 ms, and 175+/-26 ms, respectively, and did not differ. After completed right atrial surgery, these fibrillary intervals remained unchanged. Mean right and left atrial dispersion of refractoriness (expressed as the coefficient of variation) were 4.2+/-0.8 and 5.2+/-3.8 ms. Only right atrial dispersion of refractoriness increased significantly after right-sided surgery. Prior to surgery, activation patterns of the left atrium were more complex than that of the right atrium. The left activation patterns became less complex afterwards; the right atrial activation patterns did not change. CONCLUSION: The right atrial modification of maze III surgery neither affects atrial refractoriness during human lone AF nor changes AF wavelet organization. Thus, right atrial surgery does not modify the arrhythmogenic substrate of AF. These findings may imply that maze surgery can be restricted to the left atrium.     

Acute effects of left atrial radiofrequency ablation on atrial fibrillation

INTRODUCTION: Acutely, when left atrial ablation is performed during atrial fibrillation (AF), the AF may persist and require cardioversion, or it may convert to sinus rhythm or to atrial tachycardia/flutter. The prevalence of these acute outcomes has not been described. METHODS AND RESULTS: Left atrial ablation, usually including encirclement of the pulmonary veins, was performed during AF in 144 patients with drug-refractory AF. Conversion to sinus rhythm occurred in 19 patients (13%), to left atrial tachycardia in 6 (4%), and to atrial flutter in 6 (4%). In the 6 patients with a focal atrial tachycardia, the mean cycle length was 294 +/- 45 ms. The tachycardia arose in the left atrial roof in 3 patients, the left atrial appendage in 2, and the anterior left atrium in 1. In 3 of 6 patients, the focal atrial tachycardia originated in an area that displayed a relatively short cycle length during AF. In 6 patients, AF converted to macroreentrant atrial flutter with a mean cycle length of 253 +/- 47 ms, involving the mitral isthmus in 5 patients and the septum in 1 patient. All atrial tachycardias and flutters were successfully ablated with 1 to 15 applications of radiofrequency energy. CONCLUSION: When left atrial ablation is performed during AF, the AF may convert to atrial tachycardia or flutter in approximately 10% of patients. Focal atrial tachycardias that occur during ablation of AF may be attributable to driving mechanisms that persist after AF has been eliminated, whereas atrial flutter results from incomplete ablation lines.     

Regional endocardial left atrial voltage and electrogram fractionation in patients with atrial fibrillation

Introduction: Heterogeneities in electrophysiological properties may contribute to the development of atrial fibrillation, and regional disparities in endocardial voltage in the left atrium have been related to arrhythmogenic mechanisms. This study aimed at investigating endocardial voltage in different regions of the left atrium in patients with atrial fibrillation (AF). Methods and Results: Thirty‐six patients (aged 56 ± 7 years, 10 female) scheduled for circumferential ablation for paroxysmal AF were studied. Voltage measurements were performed during AF and with constant right ventricular pacing in the anterior, posterior, superior and inferior walls outside the antrum of the left (LPV), and right (RPV) pulmonary veins, by means of electroanatomical mapping. There was a high agreement among measurements performed in the endocardium of the posterior atrial wall (ICC > 0.70), and moderate agreement among measurements performed in the superior and inferior walls (0.50 < ICC< 0.70), outside both PV antra. The posterior left atrial wall demonstrated significantly higher voltages both outside the LPV antrum (1.29 ± 1.36 mV) and the RPV antrum (1.20 ± 0.63 mV) compared to the inferior, anterior and superior walls (0.47 ± 0.49, 0.68 ± 0.69, and 0.61 ± 0.83 mV outside the LPV antrum, and 0.39 ± 0.23, 0.65 ± 0.49, and 0.49 ± 0.24 mV outside the RPV antrum, respectively). Fractionated electrograms were mainly identified at the posterior left atrial wall, outside the right PV antrum. Conclusion: During AF, the posterior wall displays significantly higher voltage and electrogram fractionation compared with other parts of the left atrial endocardium outside the antra of both pulmonary veins in patients with paroxysmal AF.     

Noncontact mapping-guided catheter ablation of atrial fibrillation associated with left atrial ectopy

We report the use of a novel noncontact mapping system used to perform left atrial mapping and to guide radiofrequency ablation in two patients, each with atrial fibrillation (AF) triggered by left atrial ectopy. A noncontact multielectrode probe and ablation catheter were advanced into the left atrium through a transseptal puncture or a patent foramen ovale. Isopotential mapping delineated the focal origin at the ostium of the right lower pulmonary vein in one patient and close to the ostium of the left upper pulmonary vein in the other patient. The ablation catheter was guided to the target sites using a locator signal. The foci were ablated successfully in both patients. No recurrences of AF were observed during follow-up at 4 and 6 months, respectively.