Role of the coronary sinus in maintenance of atrial fibrillation

INTRODUCTION: Bursts of tachycardia arising in the pulmonary veins may play an important role in perpetuating atrial fibrillation (AF). However, the role of the coronary sinus (CS) in the perpetuation of AF has been unclear. The aim of this study was to determine whether the CS plays a role in perpetuation of AF. METHODS AND RESULTS: Pulmonary vein isolation was performed by segmental ostial ablation with radiofrequency energy in 22 consecutive patients with paroxysmal AF. Bipolar and unipolar electrograms recorded in the left atrium and CS were analyzed during atrial pacing from the mitral annulus and during AF. There was a mean of 2.5 +/- 0.5 electrical connections between the CS and the left atrium. The electrical connections between the left atrium and CS were ablated with a mean of 6.2 +/- 2.7 minutes of radiofrequency energy applied along the atrial side of the inferior mitral annulus. During AF, episodes of intermittent tachycardia alternated between the left atrium and the CS. Among the 22 patients, sustained AF was still inducible in 9 after pulmonary vein isolation. After electrical disconnection of the CS from the left atrium, sustained AF was inducible in only 3 of these 9 patients. CONCLUSION: The CS may be a source of rapid repetitive electrical activity during AF. The lower probability of inducible sustained AF after electrical disconnection of the CS from the left atrium suggests that the CS may play a role in perpetuating AF.     

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.     

One-stop procedure of “Atrial fibrillation radiofrequency ablation + left atrial appendage closure” guided by 3D printing technology: A case report

Left atrial appendage occlusion (LAAO) in the treatment of atrial fibrillation (AF) has become a hot topic in clinical research in recent years. We report a 68-year-old female with a 3-year history of paroxysmal atrial fibrillation refractory to antiarrhythmic therapy and unable to tolerate anticoagulation therapy who underwent successful atrial fibrillation radiofrequency ablation combined with left atrial appendage occlusion guided by 3D printing technology. There was no recurrence of her atrial fibrillation and there was continued complete occlusion of her left atrial appendage at 3-month and 1-year follow-ups.This case supports the potential advantage of 3D printing technology to guide a “one-stop combined AF radiofrequency ablation and left atrial appendage occlusion procedure.” But whether it can improve the prognosis and quality of life of patients, further multi-center research and large data statistics are required.     

Atrial Tachycardia Confined Within the Left Atrial Appendage

AT Confined Within the LAA. Left atrial tachycardias are often seen following catheter ablation of persistent atrial fibrillation (AF). We report here an unusual case where AF was converted to sinus rhythm following catheter ablation, but ongoing atrial tachycardia confined within the left atrial appendage (LAA) was observed. Although the LAA tachycardia was dissociated from the atrium in sinus rhythm, bidirectional conduction between the left atrium and the LAA was, however, demonstrated after tachycardia termination. (J Cardiovasc Electrophysiol, Vol. 21, pp. 933‐935, August 2010)     

Impact of catheter ablation of the coronary sinus on paroxysmal or persistent atrial fibrillation

Objectives: This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF).
Background: The CS musculature and connections have been implicated in the genesis of atrial arrhythmias.
Methods: Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage.
RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF.
Results: Endocardial ablation significantly prolonged CSCL by 17 ± 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 ± 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation ≥5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P ≤ 0.04.
Conclusion: Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.     

Ablating the Posterior Heart: Cardioesophageal Fistula Complicating Radiofrequency Ablation in the Coronary Sinus

Cardioesophageal fistulas (CEFs) are uncommon but life‐threatening complications of radiofrequency (RF) catheter ablation of atrial fibrillation (AF). They are usually, but not exclusively, related to ablation of the left atrial posterior wall. We report a case of a 73‐year‐old man that presented with CEF following RF ablation in the coronary sinus, highlighting the importance of esophageal temperature monitoring whenever ablating in the posterior heart.     

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。     

Idiopathic Paroxysmal Atrial Fibrillation Induced by a Focal Discharge Mechanism in the Left Superior Pulmonary Vein:

INTRODUCTION: The origin of double potentials inside the left superior pulmonary vein and their relation to the mechanisms of idiopathic paroxysmal focal atrial fibrillation (AF) are unclear. METHODS AND RESULTS: A total of 40 patients were studied. Group I included 15 patients who underwent radiofrequency catheter ablation of accessory pathway. Double potentials were found inside the left superior pulmonary vein during sinus rhythm in 10 patients and during premature atrial contractions in the remaining five patients. Group II included 25 patients with idiopathic paroxysmal AF. Double potentials were also identified in the left superior pulmonary vein. In 15 patients (Group IIA), the earliest automatic discharge during premature atrial contractions and at the onset of AF was within the left superior pulmonary vein. AF was ablated by radiofrequency energy application at the site registering double potentials. Radiofrequency ablation in the remaining 10 patients failed to terminate AF (Group IIB). The patients in Group IIA had significantly more male patients and more frequent premature atrial contractions and atrial tachycardia on 24-hour Holter recordings prior to the procedure than patients in Group IIB. CONCLUSIONS: Double potentials are present at the left superior pulmonary veins in patients with and without a history of AF. The first potential is due to the activation of atrial myocardium and the second is due to the activation of a different muscular structure. Rapid discharge of this structure triggers episodes of paroxysmal AF. Patients with focal AF originating from the left superior pulmonary vein can be identified by Holter recordings.     

Radiofrequency Catheter Ablation in Unusual Mechanisms of Atrial Fibrillation:

RF Catheter Ablation in AF. Introduction: The purpose of this study was to test the feasibility of radiofrequency (RF) catheter ablation of localized mechanisms of atrial fibrillation (AF).
Methods and Results: Three patients underwent RF catheter ablation for drug-resistant atrial arrhythmias. The first two patients had either incessant atrial tachycardia or AF. In the first patient, the KCG pattern of AF was mimicked by a very rapid atrial focus, whereas in the second patient, AF was due to true degeneration of the atrial activity triggered by atrial tachycardia. In both patients, the ablation of atrial focus led to the clinical disappearance of AF. The third patient had frequent episodes of AF, which lasted several days or weeks, and two documented episodes of atrial flutter. Mapping during AF showed an irregular atrial rhythm in the atrial septum, particularly in the region surrounding the coronary sinus, whereas the entire lateral right atrial free wall exhibited a constantly organized rhythm. RF energy was applied between the tricuspid ring and both the inferior vena cava and the coronary sinus, resulting in inability to reinduceatrial flutter or sustained AF. A 6-month follow-up in this patient showed the disappearance of prolonged episodes of AF.
Conclusion: The observations indicate that AF may be linked to "focal" mechanisms that can be treated by RF catheter ablation.     

Mitral Isthmus Ablation Using Steerable Sheath and High Ablation Power: A Single Center Experience

Case Series of Mitral Isthmus Ablation. Background: Mitral isthmus ablation is challenging. The use of steerable sheath and high ablation power may improve success rate. Methods: This single‐center, prospective study enrolled 200 patients who underwent ablation for atrial fibrillation (AF), including mitral isthmus ablation. Mitral isthmus ablation was performed using an irrigated ablation catheter via a steerable sheath (endocardium: maximum power: 40/50 W limited to annular end, maximum temperature: 48 °C; coronary sinus [CS]: maximum power: 25/30 W, maximum temperature: 48 °C). Endpoint was bidirectional mitral isthmus block. Results: Mitral isthmus block was acutely achieved in 182/200 patients (91%). Sixty‐nine percent of patients required CS ablation. Mean total ablation time was 13 ± 6 minutes. There was 1 case of acute circumflex artery occlusion. Mean left atrium (LA) diameter was significantly bigger in patients with unsuccessful mitral isthmus ablation (49 ± 4 mm vs. 43 ± 6 mm; P = 0.0007). In redo procedures, the incidence of reconduction at the mitral isthmus, roof and cavotricuspid isthmus was 44%, 37%, and 29%, respectively. Overall incidence of perimitral flutter was 9%. Prior complex fractionated atrial electrogram ablation was a predictor for microreentrant atrial tachycardia (AT) whereas gaps in linear lesions predicted macroreentrant flutters. After a mean follow‐up of 20 ± 9 months, 73% of patients remained free from AF or AT. Conclusion: We reported on a series of mitral isthmus ablation using steerable sheath and high ablation power (50 W). Larger LA diameter was a predictor of failure to achieve mitral isthmus block. The mitral isthmus had a moderately high incidence of re‐conduction but was only associated with a relatively low incidence of perimitral flutter. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1193–1200, November 2012)     

射频消融联合左心耳封堵术治疗心房纤颤17例回顾性分析

目的探讨心房颤动"一站式"手术的有效性和安全性。方法回顾性分析临床17例心房纤颤患者通过射频消融联合左心耳封堵"一站式"手术治疗后的临床资料。结果手术后出现肺部感染2例(11.76%),一过性交界性逸搏心律2例(11.76%),食管瘘1例(5.89%),术后3个月经食道超声心动图复查发现,封堵器表面血栓形成1例(5.89%),术后6个月随访无卒中、出血及死亡患者,1例患者心房颤动复发,继续抗凝治疗,其他患者均改为阿司匹林或氯吡格雷单联抗栓治疗。结论对于卒中高危且有抗凝禁忌的非瓣膜性心房颤动患者,射频消融联合左心耳封堵"一站式"手术是可行的、安全的、有效的。     

Catheter Ablation for Long-Standing Persistent Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and represents a major burden to health care systems. Atrial fibrillation is associated with a 4- to 5-fold increased risk of thromboembolic stroke. The pulmonary veins have been identified as major sources of atrial triggers for AF. This is particularly true in patients with paroxysmal AF but not always the case for those with long-standing persistent AF (LSPAF), in which other locations for ectopic beats have been well recognized. Structures with foci triggering AF include the coronary sinus, the left atrial appendage (LAA), the superior vena cava, the crista terminalis, and the ligament of Marshall. More than 30 studies reporting results on radiofrequency ablation of LSPAF have been published to date. Most of these are observational studies with very different methodologies using different strategies. As a result, there has been remarkable variation in short- and long-term success, which suggests that the optimal ablation technique for LSPAF is still to be elucidated. In this review we discuss the different approaches to LSPAF catheter ablation, starting with pulmonary vein isolation (PVI) through ablation lines in different left atrial locations, the role of complex fractionated atrial electrograms, focal impulses and rotor modulation, autonomic modulation (ganglionated plexi), alcohol ablation, and the future of epicardial mapping and ablation for this arrhythmia. A stepwise ablation approach requires several key ablation techniques, such as meticulous PVI, linear ablation at the roof and mitral isthmus, electrogram-targeted ablation with particular attention to triggers in the coronary sinus and LAA, and discretionary right atrial ablation (superior vena cava, intercaval, or cavotricuspid isthmus lines).     

Radiofrequency catheter ablation within the coronary sinus eliminates a macro-reentrant atrial tachycardia: Importance of mapping in the coronary sinus

We describe a patient who underwent radiofrequency (RF) catheter ablation of symptomatic atrial fibrillation. After left atrial (LA) catheter ablation and pulmonary vein isolation, a macro-reentrant atrial tachycardia (AT) with a critical isthmus at the mitral isthmus was induced by incremental atrial pacing from the coronary sinus. Extensive RF energy applications from endocardial sites using ablation catheters with 4 mm- and 8 mm- tips resulted in no discrete potentials being recorded from the endocardial sites of the isthmus, but the tachycardia could not be terminated. However, discrete potentials were recorded within the CS, and epicardial RF energy applications from the CS eliminated the tachycardia. Thus, mapping in the CS is useful for detecting residual conduction at epicardial sites along the mitral isthmus. RF catheter ablation within the CS should be considered when no distinct electrograms are recorded after extensive ablation from the endocardial sites and when distinct electrograms are recorded within the CS.     

Coronary artery dissection following radiofrequency ablation for atrial fibrillation: Case report and review of the literature

Coronary artery injury following catheter ablation for cardiac arrhythmias is very rare. We present a case of left circumflex (LCx) coronary artery dissection causing inferoposterior ST-elevation myocardial infarction following radiofrequency (RF) ablation for atrial fibrillation (AF) in a 39-year-old male with no cardiovascular risk factors. This was confirmed on coronary angiography and intracoronary vascular ultrasound (IVUS). The likely etiology is thermal injury during RF ablation for AF, due to the close proximity of the left atrial appendage and left pulmonary veins to the LCx. He was successfully treated with primary percutaneous coronary intervention with good outcome. This is, to our knowledge, the first reported case of proven acute coronary dissection secondary to RF ablation for AF reported in the literature, and highlights the importance of considering this as a mechanism for coronary occlusion in these patients.     

Epicardial foci of atrial arrhythmias apparently originating in the left pulmonary veins

INTRODUCTION: Epicardial potential sources of atrial arrhythmias, such as the ligament of Marshall, are in close proximity with, and electrically connected to, the left superior pulmonary vein. Ectopic activity arising from these areas may be difficult to differentiate from ectopy that, according to endocardial only mapping, originates in the left superior pulmonary vein. We hypothesized that in patients with paroxysmal atrial fibrillation (AF) apparently originating in the left pulmonary veins, mapping through the distal coronary sinus might identify possible epicardial locations of the arrhythmogenic focus. METHODS AND RESULTS: Forty patients (age 48 +/- 12 years) who underwent catheter ablation for paroxysmal AF were studied by epicardial mapping through the distal, superoposterior coronary sinus. Catheterization of the distal coronary sinus in order to approach the ostium of the left superior pulmonary vein was feasible in 14 of 19 patients with AF originating in the left superior vein (11 patients) or inferior pulmonary vein (3 patients) according to endocardial mapping criteria. In 2 patients, the sole focus of atrial tachycardia/fibrillation was epicardial with earliest activation clearly preceding electrograms recorded at the os of the left superior pulmonary vein or any other endocardial mapping site. Epicardial potentials separated from atrial electrograms were present during sinus rhythm in both patients and during atrial tachycardia in one patient. Catheter ablation through the coronary sinus rendered the arrhythmia noninducible in both patients without abolishing epicardial potentials in one of them. CONCLUSION: In patients with paroxysmal AF apparently originating from the left superior or inferior pulmonary vein, detailed epicardial mapping through the distal coronary sinus might identify epicardial locations of the arrhythmogenic focus.     

Bi-focal atrial tachycardia mimicking atrial fibrillation: fusion and interference between two distinct tachycardias

Irregular tachycardias mimicking atrial fibrillation (AF) have previously been described. We report a case of a 60-year-old man with an antiarrhythmic drug-resistant atrial tachycardia (AT) mimicking AF. The tachycardia consisted of two distinct ATs with interference of one repetitive AT with another sustained AT. Radiofrequency (RF) ablation of two distinct right atrial foci eliminated the irregular tachycardia. Although catheter-based pulmonary vein isolation has become a popular therapeutic approach for patients with symptomatic AF, careful evaluation of the intracardiac recordings in the patients undergoing RF ablation for AF is important.     

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。     

Catheter ablation of regular atrial arrhythmia following surgical treatment of permanent atrial fibrillation

Ablation of Atrial Tachycardia after Antiatrial Fibrillation Surgery. INTRODUCTION: Surgical treatment of atrial fibrillation (AF) is gaining widespread acceptance. However, therapeutic modalities for secondary regular atrial tachycardia are still empiric. METHODS AND RESULTS: After linear atrial cooled-tip radiofrequency ablation (SICTRA) during cardio-surgical procedures to cure permanent AF, patients with regular atrial tachycardia were identified. Invasive electrophysiology including electroanatomic mapping was performed. Catheter ablation was directed to suppress atrial arrhythmia depending on activation mapping findings. Follow-up was performed after 3 months and then after every 6 months. Of 238 patients, 12 (5.0%) were identified with regular secondary arrhythmias (12 +/- 7 months after surgery) including 9 (3.8%) with persistent forms originating from the right atrium (RA) in six (66%) (isthmus-dependent macroreentry in 4, incisional macroreentry in 1, and RA ectopy in 1). All patients with RA origin of the tachycardia were successfully ablated. Two patients had left atrial (LA)-macroreentry circling around the mitral valve indicating insufficiency of the intraoperative ablation procedure: one patient was successfully ablated within the LA isthmus, in the other patient no complete conduction block could be induced. One patient had LA-macroreentry degenerating into AF, and ablation was not performed. During follow-up (9 +/- 4 months), no recurrences of atrial tachycardias were documented after successful ablation. CONCLUSIONS: Persistent regular "secondary" arrhythmia occurred in 3.8% (9/238) of patients after SICTRA to treat permanent AF. Predominantly (67%; 6/9), the arrhythmia was located in the RA mostly incorporating the RA-isthmus. Catheter ablation was highly effective for RA tachycardia (100%). In three cases (33%), LA-macroreentry was documented and catheter ablation was successful in only one patient (overall success 78%).     

A single pulmonary vein as electrophysiological substrate of paroxysmal atrial fibrillation

Introduction: It has been demonstrated that pulmonary veins (PVs) play an important role in initiation and maintenance of paroxysmal atrial fibrillation (AF). However, it is not clearly known whether a single PV acts as electrophysiological substrate for paroxysmal AF.
Methods and Results: This study included five patients with paroxysmal AF. All patients underwent complete PV isolation with continuous circular lesions (CCLs) around the ipsilateral PVs guided by a three-dimensional mapping system. Irrigated radiofrequency (RF) delivery was performed during AF on the right-sided CCLs in two patients and on the left-sided CCLs in three patients. The incomplete CCLs resulted in a change from AF to atrial tachycardia (AT), which presented with an identical atrial activation sequence and P wave morphology. Complete CCLs resulted in AF termination with persistent PV tachyarrhythmias within the isolated PV in all five patients. PV tachyarrhythmia within the isolated PV was PV fibrillation from the left common PV (LCPV) in two patients, PV tachycardia from the right superior PV (RSPV) in two patients, and from the left superior PV in one patient. All sustained PV tachyarrhythmias persisted for more than 30 minutes, needed external cardioversion for termination in four patients and a focal ablation in one patient. After the initial procedure, an AT from the RSPV occurred in a patient with PV fibrillation within the LCPV, and was successfully ablated.
Conclusion: In patients with paroxysmal AF, sustained PV tachyarrhythmias from a single PV can perpetuate AF. Complete isolation of all PV may provide good clinical outcome during long-term follow-up.     

Atypical left atrial flutter after intraoperative radiofrequency ablation of chronic atrial fibrillation: successful ablation using three-dimensional electroanatomic mapping

Curative treatment of chronic atrial fibrillation (AF) remains a challenging task for electrophysiologists. Eliminating the initiating triggers by focal radiofrequency ablation in a subset of patients with paroxysmal AF and modifying the maintaining substrate by performing linear lesions within the left atrium in patients with prolonged episodes of AF are among the alternative approaches for management of these patients. Recently, a new intraoperative treatment procedure aimed at eliminating left atrial anatomic "anchor" reentrant circuits by induction of contiguous lesions using radiofrequency energy under direct vision was introduced. However, atypical left atrial flutter may occur during follow-up after intraoperative ablation of AF. These arrhythmias most likely are due to discontinuities in linear lesions; therefore, they can be successfully mapped and ablated in a subsequent percutaneous catheter ablation procedure. We report and discuss the case of a patient who underwent successful intraoperative ablation of chronic AF, but who developed atypical left atrial flutter postoperatively. Three-dimensional nonfluoroscopic electroanatomic mapping revealed a gap in the linear lesion line connecting the left upper and right upper pulmonary vein orifices. Ablation at the exit site of the breakthrough was successful.