Real-time monitoring of luminal esophageal temperature during left atrial radiofrequency catheter ablation for atrial fibrillation: observations about esophageal heating during ablation at the pulmonary vein ostia and posterior left atrium

INTRODUCTION: Left atrial radiofrequency catheter ablation (RFA) is gaining acceptance as treatment for drug-refractory atrial fibrillation (AF). This therapy has been associated with esophageal injury and atrioesophageal fistula formation causing death. METHODS: We describe 3 patients undergoing catheter ablation for AF during real-time monitoring of luminal esophageal temperature. RESULTS: We observed heating of the esophagus during short duration low power RFA, at either the left or right pulmonary vein ostia. Cryoablation at the pulmonary vein ostium in one patient resulted in esophageal cooling. Furthermore, we observed that fluoroscopic localization of the ablation catheter at a site apparently distant from the esophagus is not adequate to assure avoidance of ablation-induced esophageal heating. CONCLUSIONS: Real-time monitoring of luminal esophageal position and temperature is feasible, enhances recognition of esophageal heating, and may add useful information beyond that provided by fluoroscopic assessment of esophageal position. There is a potential role for esophageal monitoring to help avoid thermal injury to the esophagus during catheter ablation for atrial fibrillation.     

Flutter localized to the anterior left atrium after catheter ablation of atrial fibrillation

INTRODUCTION: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation. METHODS: A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping. RESULTS: Fourteen patients (11 female, 65 +/- 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete -/+ or +/-/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 +/- 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 +/- 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low-amplitude, fractionated mid-diastolic potentials with long duration (200 +/- 80 msec) occupying 63 +/- 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility. CONCLUSION: Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area.     

Morphological changes of the left atrial appendage after catheter ablation of atrial fibrillation

Introduction: The left atrial appendage (LAA) has been proven to be the most important site of thrombus formation in patients with atrial fibrillation (AF). However, the information regarding the morphometric alteration of the LAA related to the outcome of AF ablation is still lacking. Thus, we evaluated the long-term changes of the LAA morphology in patients undergoing catheter ablation of AF using magnetic resonance angiography (MRA).
Methods and Results: Group 1 included 15 controls without any AF history. Group 2 included 40 patients with drug-refractory paroxysmal AF. They were divided into two subgroups: group 2a included 30 patients without AF recurrence after pulmonary vein (PV) ablation. Group 2b included 10 patients with late recurrence of AF. The LAA morphology before and after (20 ± 11 months) ablation was evaluated by three-dimensional MRA. The group 2 patients had a larger baseline LAA size (including the LAA orifice, neck, and length) and less eccentric LAA orifice and neck. After the AF ablation, there was a significant reduction in the LAA size in the group 2a patients, and the morphology of the LAA neck became more eccentric during the follow-up period. In group 2b, the LAA size increased and no significant change in the eccentricity of the orifice and neck could be noted.
Conclusions: The morphometric remodeling of the LAA in the AF patients could be reversed after a successful ablation of the AF. Progressive dilation of the LAA was noted in the patients with AF recurrence. These structural changes in the LAA may play a role in reducing the potential risk of cerebrovascular accidents.     

Echocardiographic assessment of left atrial function for prediction of efficacy of catheter ablation for atrial fibrillation

Proper selection for catheter ablation (CA) for atrial fibrillation (AF) is still an issue. Echocardiographic assessment of left atrium (LA) is complex and challenging. Speckle tracking echocardiography (STE) with recent standardized LA deformation analysis allows for the quantitative assessment of various LA function parameters. We aimed to assess the value of detailed evaluations of LA function using STE in patients with non-valvular AF without structural heart disease to predict the outcomes after CA for AF. Secondary aim was to analyze the prediction of CA efficacy in patients with normal LA dimension in baseline echocardiography.We studied with transthoracic and transesophageal echocardiography 82 patients (58% males, mean age 57.3 ± 9.5 years) with non-valvular paroxysmal AF without structural heart disease scheduled for CA. Peak longitudinal LA strain (LAS) and strain rate (LASR) during the reservoir (r), conduit (cd) and contraction (ct) phases were measured by STE before the procedure. Patients were followed for 1 year using serial 4 to 7 day Holter ECG monitoring.Complete freedom from any AF recurrence was achieved in 44 (54%) patients. All patients had normal left ventricular systolic and diastolic function and 53 (65%) of them had not enlarged LA. In the multivariable logistic regression analysis, global left atrial reservoir strain (LASr) was identified as an independent predictor of CA efficacy (OR [95% CI]: 1.35 [1.17–1.55], P < .0001). The opportunity of CA success was 135 fold higher for each 1% increase in global LASr.The receiver operating characteristic (ROC) analysis identified global LASr and left atrial conduit strain (LAScd) as the most powerful parameters for predicting of CA outcome with an area under the curve of 0.896 and 0.860, respectively, in the whole study group, and 0.922 and 0.938, respectively, in patients with not enlarged LA.In patients with paroxysmal AF and normal standard echocardiographic assessment, parameters reflecting LA compliance - reservoir and conduit strain, are independent and strong predictors of CA outcome.     

无左心房和肺静脉三维重建的阵发性心房颤动导管消融术

目的探讨无左心房和肺静脉三维重建与有左心房三维重建的Carto系统引导下阵发性心房颤动（房颤）导管消融术的差异。方法入选2008年1月至12月在本中心由同一位熟练术者行Carto系统引导下导管消融术的阵发性房颤患者31例,其中17例接受无左心房和肺静脉三维重建的消融术（非重建组）,14例接受有左心房三维重建的消融术（重建组）。具体消融方法为以环肺静脉电隔离为基础,按照个体情况选择是否行三尖瓣峡部画线消融。消融终点均为肺静脉电位与心房完全隔离,电生理检查不可诱发持续的房颤、心房扑动和房性心动过速。对比上述两组患者消融术中各步骤的耗时情况,并进行随访。结果重建组男女比例为10：4,非重建组为11：6,P〉0．05;重建组年龄（54．64±15．58）岁,非重建组（59．41±10．59）岁,P〉0．05;重建组房颤病程（5．05±10．4）年,非重建组为（7．34±7．74）年,P〉0．05。重建组左心房内径（35．29±4．73）mm,非重建组是（36．47±6．15）mm,P〉0．05。重建组消融术时间（107．23±28．92）min,非重建组是（93．47±26．09）min,P〉0．05;重建组X线曝光时间（21．09±6．49）min,非重建组是（14．16±5．35）min,P〈0．05;重建组环右肺静脉消融时间（27．29±18．53）min,非重建组是（18．00±4．51）min,P〈0．05;重建组环左肺静脉消融时间（28．14±9．26）min,非重建组是（23．94±7．10）min,P〈0．05。消融术后随访2～13个月,重建组85．7％无明显房颤发作,非重建组是82．4％（P〉0．05）。结论与有左心房三维重建的Carto系统引导下的阵发性房颤导管消融术相比,无左心房和肺静脉三维重建可以缩短消融术和x线曝光时间,可以达到相同的消融效果。     

Incidence of atrial fibrillation post-cavotricuspid isthmus ablation in patients with typical atrial flutter: left-atrial size as an independent predictor of atrial fibrillation recurrence

Introduction: Atrial fibrillation and atrial flutter often coexist. The long-term occurrence of atrial fibrillation in patients presenting with atrial flutter alone is unknown. We report the long-term follow-up in patients who underwent cavotricuspid isthmus ablation for treatment of lone atrial flutter.
Methods and Results: Between January 1997 and June 2002, 632 patients underwent cavotricuspid isthmus ablation for the treatment of typical atrial flutter at the Cleveland Clinic Foundation. Three hundred sixty-three patients were included in this study and followed for a mean duration of 39 ± 11 months. The mean duration of atrial flutter symptoms was 12 ± 5 months. Mean left-atrial size and left-ventricular ejection fraction were 4.2 ± 0.8 cm and 47 ± 13%, respectively. After a mean follow-up time of 39 ± 11 months, 13% (48 of 363) of the patients remained in sinus rhythm. Five percent (18 of 363) of patients experienced recurrence of atrial flutter only. Sixty-eight percent (246 of 363) experienced the onset of atrial fibrillation and 14% (51 of 363) experienced recurrence of atrial flutter and the new onset of atrial fibrillation. Overall, 82% (297 of 363) of the patients experienced new onset of drug refractory atrial fibrillation. Left-atrial size was a predictor of atrial fibrillation recurrence post-atrial flutter ablation.
Conclusion: At long-term follow-up, approximately 82% of patients post-cavotricuspid isthmus ablation for atrial flutter developed drug refractory atrial fibrillation. This finding suggests that elimination of atrial flutter might delay, but does not prevent, atrial fibrillation. Evidence suggests both arrhythmias may share common triggers and such patients may derive a better long-term benefit from anatomical ablative treatment of atrial fibrillation as well.     

Impaired transport function of the left atrium in patients with lone paroxysmal atrial fibrillation

Background: Although lone paroxysmal atrial fibrillation (LPAF) is clinically defined as an arrhythmia that occurs in the absence of structural heart disease, it has been suggested that the presence of anatomical substrate is related to LPAF. The aim of the present study is to determine whether structural and functional remodeling of the left atrium (LA) occurs in patients with LPAF, and to identify whether frequent episodes of atrial fibrillation (AF) contribute to LA remodeling. Methods and Results: Forty‐five patients who diagnosed as LPAF and age‐, gender‐, and body mass index‐matched healthy control subjects (n = 45) were enrolled. Patients were grouped based on the frequency of AF episodes. An echocardiography was performed >2 weeks after last episode of AF without antiarrhythmic drugs. There were no statistical differences in left ventricular (LV) diastolic and systolic functions as well as baseline characteristics between patients and controls, whereas, patients had significantly larger LA volume (LAV), lower active LA emptying fraction (LAEF_active, P = 0.009) and total LAEF (LAEF_total, P = 0.005) compared with controls. Passive LAEF (LAEF_passive) was not different between patients and controls (P = 0.664). LAEF_active was significantly depressed in patients with frequent episodes of AF than the others (P = 0.034). Conclusions: Compared with healthy controls, patients with LPAF had increased LAV and depressed LAEF_active and LAEF_total without accompanying compensatory increase in LAEF_passive. LAEF_active was influenced by frequent episodes of AF. These findings may support the hypothesis that LPAF is “not‐so‐lone AF” and related to the concealed cardiac dysfunctions. (Echocardiography 2011;28:44‐51)     

Three-dimensional anatomy of the left atrium by magnetic resonance angiography: implications for catheter ablation for atrial fibrillation

BACKGROUND: Pulmonary vein isolation (PVI) has become one of the primary treatments for symptomatic drug-refractory atrial fibrillation (AF). During this procedure, delivery of ablation lesions to certain regions of the left atrium can be technically challenging. Among the most challenging regions are the ridges separating the left pulmonary veins (LPV) from the left atrial appendage (LAA), and the right middle pulmonary vein (RMPV) from the right superior (RSPV) and right inferior (RIPV) pulmonary veins. A detailed anatomical characterization of these regions has not been previously reported. METHODS: Magnetic resonance angiography (MRA) was performed in patients prior to undergoing PVI. Fifty consecutive patients with a RMPV identified by MRA were included in this study. Ridges associated with the left pulmonary veins were examined in an additional 30 patients who did not have a RMPV. Endoluminal views were reconstructed from the gadolinium-enhanced, breath-hold three-dimensional MRA data sets. Measurements were performed using electronic calipers. RESULTS: The width of the ridge separating the LPV from the LAA was found to be 3.7 +/- 1.1 mm at its narrowest point. The segment of this ridge with a width of 5 mm or less was 16.6 +/- 6.4 mm long. The width of the ridges separating the RMPV from the RSPV and the RIPV was found to be 3.0 +/-1.5 mm and 3.1 +/-1.8 mm, respectively. There were no significant differences between LPV ridges for patients with versus without a RMPV. CONCLUSION: The width of the ridges of atrial tissue separating LPV from the LAA and the RMPV from its neighboring veins may explain the technical challenge in obtaining stable catheter positions in these areas. A detailed assessment of the anatomy of these regions may improve the safety and efficacy of catheter ablation at these sites.     

Cardiac anatomy pertinent to the catheter and surgical treatment of atrial fibrillation

In the 1980s when surgery was first introduced for the treatment of atrial fibrillation (AF), one would often hear comments like “Every little old grandmother has AF. Why on earth would you operate on someone like that?”.     

Effect of presenting rhythm on image integration to direct catheter ablation of atrial fibrillation

INTRODUCTION: Magnetic resonance (MR) imaging of the left atrium (LA) can be integrated with electroanatomic mapping systems to guide catheter ablation of atrial fibrillation (AF). The usefulness of this technique is dependent on the accuracy of image integration. OBJECTIVE: The aim of this study is to determine the effect of heart rhythm at the time of pre-procedure MR imaging and heart rhythm at the time of ablation on integration error. METHODS: Fifty-two consecutive patients who underwent catheter ablation for AF were included. All patients underwent MR imaging of LA and pulmonary veins and image integration with real-time electroanatomic mapping. The rhythm at the time of MR imaging and on the day of ablation was recorded. CARTO-Merge software (Biosense-Webster) was used to calculate the average accuracy of integration of electroanatomic points with MR-derived reconstructions. RESULTS: There was no significant difference in integration error between patients who were in AF at the time of their MR vs. those who were in sinus rhythm at the time of their MR (1.76 +/- 0.26 vs. 1.88 +/- 0.31 mm, p = 0.15). There was also no significant difference in integration error between patients who were in concordant vs. discordant rhythms at the time of MR vs. day of ablation (1.81 +/- 0.23 vs. 1.89 +/- 0.32 mm, p = 0.40). There was a trend toward less integration error between patients who were in AF on the day of ablation vs. those in sinus rhythm (1.74 +/- 0.26 vs. 1.89 +/- 0.31 mm, p = 0.07). CONCLUSIONS: Image integration can be performed to direct catheter ablation of AF regardless of the rhythm at the time of imaging and ablation.     

Impact of heart rhythm status on registration accuracy of the left atrium for catheter ablation of atrial fibrillation

Introduction: Registration accuracy is of crucial importance to the successful use of image integration technique to facilitate atrial fibrillation (AF) ablation. It is well known that a patient's heart rhythm can switch from sinus rhythm (SR) to AF or vice versa during an AF ablation procedure. However, the impact of the heart rhythm change on the accuracy of left atrium (LA) registration has not been studied. Methods: This study included 10 patients who underwent AF ablation. Prior to the ablation procedure, the patients had contrast‐enhanced cardiac CT scan obtained during SR (n = 7) or AF (n = 3). Using an image integration system (CartoMerge, Biosense Webster Inc.), LA CT surface reconstruction was registered to the real‐time mapping space represented by the LA electroanatomic map. To determine the effect of rhythm change on registration accuracy, LA registration was performed during both SR and AF in each study subject. The distance between the surface of the registered LA CT reconstruction and multiple real‐time LA electroanatomic map points (surface‐to‐point distance) was used as an index for LA registration error. The position error after rhythm change was defined as the surface‐to‐point distance between the surface of the LA CT reconstruction registered in the initial rhythm and the LA electroanatomic map points sampled during the second rhythm. Results: A total of 90 ± 12 and 92 ± 9.5 LA electroanatomic map points were sampled for registration during SR and AF, respectively. No significant difference was found in surface‐to‐point distance when comparing SR with AF as the underlying rhythm during registration (1.91 ± 0.24 vs 1.84 ± 0.38 mm, P = 0.60). The position error after rhythm change was not different from the surface‐to‐point distance of LA registration conducted during the initial rhythm (2.05 ± 0.39 vs 1.96 ± 0.29 mm, P = 0.4). The surface‐to‐point distance did not differ when comparing LA registration conducted during the same versus different rhythm from that during CT imaging (1.96 ± 0.29 vs 1.79 ± 0.32 mm, P = 0.13). Conclusions: Registration error did not differ between LA registrations conducted during the same versus different rhythm as was present during CT imaging. Rhythm changes between SR and AF did not introduce significant error to the LA registration process for catheter ablation of AF. These findings are reassuring and suggest that reregistration is not needed if a patient's rhythm changes from SR to AF or vice versa during an ablation procedure.     

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。     

Temporal stability of the location of the esophagus in patients undergoing a repeat left atrial ablation procedure for atrial fibrillation or flutter

Background: The esophagus may be mobile during a left atrial (LA) ablation procedure for atrial fibrillation (AF).
Objective: The goal of the study was to determine whether the location of the esophagus is stable in patients undergoing a repeat LA ablation procedure.
Methods: Forty-two patients underwent repeat LA ablation a mean of 7 ± 2 months after the initial procedure. Cinefluoroscopic images of the esophagus during a barium swallow were recorded and the course of the esophagus was tagged on the 3D map. The position of the esophagus at the index and repeat procedure were compared.
Results: At the index procedure, the esophagus was located near the left pulmonary veins (PVs) in 20 (48%), right PVs in 13 (31%), and at the mid LA in 9 (21%) patients. During the repeat procedure, the esophagus was found to be near the left PVs in 22 (52%), right PVs in 11 (26%), and at the mid LA in 9 patients (21%). In 35 of the 42 patients (83%), there was no change in the esophageal location, and in the remaining seven patients (17%), its position had shifted by ≥1 cm (range 1.0–4.0 cm).
Conclusions: In more than 80% of patients presenting for a repeat LA ablation procedure, the esophagus is in the same position relative to the PVs as during the initial procedure. Therefore, if radiofrequency ablation at a particular location was limited by the position of the esophagus, safe ablation at that site is unlikely to be feasible during a repeat procedure.     

Integration of cardiac CT/MR imaging with three-dimensional electroanatomical mapping to guide catheter manipulation in the left atrium: implications for catheter ablation of atrial fibrillation

Introduction: Preprocedural cardiac imaging (CT/MRI) and intraprocedural electroanatomical mapping (EAM) are commonly used during left atrial (LA) catheter ablation of atrial fibrillation (AF). In the optimal scenario, the imaging datasets would be directly integrated with the EAM system to guide catheter mapping based on the accurate individual cardiac anatomy.
Methods and Results: Strategies to align the EAM and imaging data were assessed by simulations using a life-size model of the LA and aorta. This revealed that the optimal strategy includes mapping both the aorta and LA. Respiratory changes in cardiac anatomy were evaluated by MR angiography performed in 10 patients during both inspiration and expiration. Comparison of paired images revealed inferior and anterior movement of the LA relative to the aorta with inspiration. Next, image integration was employed in a series of patients (n = 13) scheduled for AF catheter ablation. After preprocedural CT angiography (7 during inspiration and 6 during expiration), three-dimensional anatomical renderings of these images were integrated with the EAM data in a custom workstation to permit real-time catheter manipulation within these constructs. The electrophysiologist was blinded to these integrated images, but the accuracy of the process was assessed real-time by a second operator. This revealed poor alignment during inspiration but good alignment during expiration—the respiratory phase most closely resembling that during EAM.
Conclusions: This study supports the feasibility of integrating preacquired cardiac images with real-time electroanatomical mapping to guide catheter movement in the LA in a reliable and clinically relevant manner.     

Topographic variability of the esophageal left atrial relation influencing ablation lines in patients with atrial fibrillation

Topography of the esophagus in atrial fibrillation ablation. INTRODUCTION: The close anatomic relationship of the posterior wall of the left atrium (LA) and the thermosensitive esophagus creates a potential hazard in catheter ablation procedures. METHODS AND RESULTS: In 30 patients (pts) with atrial fibrillation (AF) undergoing catheter ablation, we prospectively studied the course and contact of the esophagus in relation to LA and the topographic proximity to ablation lines encircling the right-sided and left-sided pulmonary veins (PV) as well as to the posterior line connecting the encircling lines using the electromagnetic mapping system for reconstruction of LA and for tagging of the esophagus. This new technique of anatomic tagging of the esophagus was validated against the CT scan as a standard imaging procedure. The esophageal course was highly variable, extending from courses in direct vicinity to the left- or right-sided PV as well as in the midportion of the posterior LA. In order to avoid energy application in direct proximity to the esophagus, adjustments of the left and right PV encircling lines were necessary in 14/30 pts (47%) and 3/30 (10%). In 30 pts (100%), the mid- to inferior areas of the posterior LA revealed contact with the esophagus. Therefore, posterior and inferior linear ablation lines were abandoned and shifted to superior in 29 pts (97%). CONCLUSIONS: Anatomic tagging of esophagus revealed a highly variable proximity to different areas of the posterior LA suggesting individual adjustment of encircling and linear ablation lines in AF ablation procedures to avoid the life threatening complication of esophagus perforation.