Computed tomographic analysis of the esophagus, left atrium, and pulmonary veins: implications for catheter ablation of atrial fibrillation

Purpose:

The aim of this study was to investigate the anatomic relationship around the left atrium (LA) and to provide clinical information to help avoid the risk of an atrio-esophageal fistula during atrial fibrillation (AF) ablation.

Methods:

The multidetector spiral computed tomography images of 77 male patients (mean age, 54?±?9 years) with drug-refractory AF and 37 male control subjects (mean age, 50?±?11 years) were analyzed. We measured the following variables: (1) distance between the ostia of the pulmonary veins (PVs) and the ipsilateral esophageal border, (2) presence of a pericardial fat pad around each PV, and (3) contact width/length and presence of a fat pad between the LA and the esophagus.

Results:

The distance between the esophagus and the ostia of right superior PV, right inferior PV (RIPV), left superior PV, and left inferior PV (LIPV) was 27.2?±?9.4 mm, 22.9?±?10.3 mm, 2.7?±?9.4 mm, and 7.1?±?8.8 mm, respectively. A fat pad between the esophagus and the superior PV was present in more than 90% of the subjects in both groups. However, the fat pad around inferior PV was present less frequently in the patients than in the control group (p?=?0.011, RIPV; p?<?0.001, LIPV). The average length of the LA?Cesophagus contact in the patients and the control group subjects was 26.2?±?10.4 and 18.5?±?5.1 mm, respectively (p?<?0.001).

Conclusion:

Caution should be exercised when ablating the LIPV because the esophagus is located in close proximity to the left-sided PV and most of the inferior PVs in patients with AF are not covered with fat pads.     

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.     

Anatomic relationship of the esophagus and left atrium: implication for catheter ablation of atrial fibrillation

STUDY OBJECTIVES: Atrioesophageal fistulas have been reported to be a lethal complication following catheter ablation of atrial fibrillation (AF). The purpose of this study was to investigate the relationship between the esophagus and posterior left atrium (LA) and provide the anatomic information necessary to minimize the risk of esophageal injury during AF ablation. METHODS AND RESULTS: Forty-eight patients (43 men; mean +/- SD age, 59 +/- 12 years) with drug-refractory paroxysmal AF and 32 control subjects (26 men; mean age, 60 +/- 9 years) were included. All underwent a CT scan for delineation of the relationship between the esophagus and posterior LA. In the paroxysmal AF group, two major types of esophageal routes were demonstrated. Type 1 routes were found in 42 patients with the lower portion of esophagus close to the ostium of the left inferior pulmonary vein (LIPV), including three subtypes of courses according to the proximity to the left superior pulmonary vein (PV) and LIPV. Type 2 routes were found in six patients with the lower portion of esophagus close to the ostium of the right inferior pulmonary vein (RIPV), including three subtypes of courses according to the proximity to the right superior PV and RIPVs. The mean shortest distance of the esophagus to the four individual PVs significantly differed between type 1 and type 2: 28.4 +/- 6.1 mm vs 10.5 +/- 5.7 mm (to the right superior), 19.6 +/- 7.0 mm vs 3.7 +/- 3.4 mm (to the right inferior), 10.1 +/- 3.4 mm vs 22.8 +/- 4.2 mm (to the left superior), and 2.8 +/- 2.5 mm vs 18.7 +/- 5.2 mm (to the left inferior), respectively (p < 0.001 for all). Contact of the esophagus and middle part of posterior LA was observed in each patient. However, direct contact of the aorta with the posterior LA wall was more frequent in type 2 than in type 1 (p = 0.001). The clinical characteristics, type of esophageal routes, distance from the esophagus to the four PVs, and diameter of the thoracic cage, LA, and aorta in the control group were similar to those in the AF group (p > 0.05 for all). CONCLUSION: Although the anatomic relationship between the esophagus and LA posterior wall varied widely, two major patterns of esophageal routes could be depicted. This information is important for deciding the location of the ablation lesions around the PV ostia and LA and for avoiding the potential risk of esophageal injury.     

Movement of the esophagus during left atrial catheter ablation for atrial fibrillation.

OBJECTIVES: The aim of this study was to describe the extent of esophageal mobility that occurs during catheter ablation for atrial fibrillation under conscious sedation. BACKGROUND: Ablation along the posterior left atrium may cause an atrioesophageal fistula. One strategy for avoiding this risk is to not deliver radiofrequency energy at sites in contact with the esophagus. METHODS: In 51 consecutive patients with atrial fibrillation who underwent left atrial ablation under conscious sedation, digital cine-fluoroscopic imaging of the esophagus was performed in two views after ingestion of barium paste at the beginning and end of the ablation procedure. Movement of the esophagus was determined at the superior, mid-, and inferior parts of the posterior left atrium in reference to the spine. RESULTS: Mean esophageal movement was 2.0 +/- 0.8 cm (range = 0.3 to 3.8 cm) at the superior, 1.7 +/- 0.8 cm (range = 0.1 to 3.5 cm) at the mid-, and 2.1 +/- 1.2 cm (range = 0.1 to 4.5 cm) at the inferior levels. In 67% of the 51 patients, the esophagus shifted by > or =2 cm, and in 4% there was > or =4 cm of lateral movement. The mean change in esophageal luminal width was 5 +/- 7 mm (range = 0 to 36 mm) at the superior, 5 +/- 7 mm (range = 0 to 32 mm) at the mid-, and 6 +/- 7 mm (range = 0 to 21 mm) at the inferior levels of the posterior left atrium. CONCLUSIONS: The esophagus often is mobile and shifts sideways by > or=2 cm in a majority of patients undergoing catheter ablation for atrial fibrillation under conscious sedation. Therefore, real-time imaging of the esophagus may be helpful in reducing the risk of esophageal injury during radiofrequency ablation along the posterior left atrium.     

Relationship of the esophagus and aorta to the left atrium and pulmonary veins: Implications for catheter ablation of atrial fibrillation

BACKGROUND: A potential complication during ablation of atrial fibrillation (AF) is damage to adjacent structures such as the esophagus and aorta. Fatal atrio-esophageal fistulas have developed after surgery- or catheter-based AF ablation procedures. OBJECTIVES: The purpose of this study was to analyze multidetector computed tomography (MDCT) angiographic images to determine the anatomic relationship of the aorta and esophagus to the left atrium (LA). METHODS: Sixty-five subjects underwent CT imaging using a 16-slice MDCT scanner: 24 with paroxysmal AF, 21 with chronic AF, and 20 "control" subjects without a history of AF. Measurements assessed included LA diameters, width of the esophagus and aorta in contact with the posterior LA wall, and distance from the esophagus to the four pulmonary veins (PVs), spine, and LA endocardium. RESULTS: Mean LA diameters were significantly larger in patients with AF vs the control group (P = .003 for anteroposterior diameter; P = .009 for transverse diameter). The anterior aspect of the esophagus was directly apposed to the LA in all cases (contact width 18.9 +/- 4.4 mm). The position of the esophagus varied in the posterior mediastinum but on average was closer to the ostia of the left PVs (P = .0001). The descending aorta was in contact with the LA and/or left PVs in 50 of 65 subjects. The esophagus was closer to the spine in the chronic AF vs control group (P = .007), likely due to increased LA dimension. CONCLUSION: In addition to its ability to assess PV anatomy, preprocedural MDCT imaging can investigate the variable relationship of adjacent structures, such as the esophagus and aorta to the LA and PVs.     

Anatomy of the left atrium: implications for radiofrequency ablation of atrial fibrillation

INTRODUCTION: The feasibility of treating atrial fibrillation with radiofrequency ablation has revived interest in the structure of the left atrium, a chamber that has been neglected in many textbooks of anatomy. METHODS AND RESULTS: We reviewed the gross structure of the left atrium by examining the septum, the appendage, and insertions of the pulmonary veins in normal hearts. The limited extent of the true septal component is relevant to procedures using the transseptal approach. On gross examination, the musculature of the atrial wall is composed of overlapping bundles of aligned fibers that, in the majority of hearts, are arranged in characteristic patterns with only minor individual variations. Muscular sleeves extend into the walls of the pulmonary veins to varying distances. The longest sleeves are in the left upper veins. Bachmann's bundle anteriorly, and other smaller bundles superiorly and posteriorly, bridge the septal raphe to blend with musculature of the right atrium. Tongues of left atrial musculature from the posterior wall also extend into the wall of the coronary sinus. CONCLUSION: The left atrium is more complex than usually conceived. Understanding its structure, and the arrangement of its musculature, will help in improving strategies for linear lesions when attempting to compartmentalize the chamber, or when placing focal lesions for ablating ectopic sources.     

Intraprocedural volume imaging of the left atrium and pulmonary veins with rotational X-ray angiography: implications for catheter ablation of atrial fibrillation

Introduction: The use of preprocedural CT or MR imaging to generate patient-specific cardiac anatomy greatly facilitates catheter ablation of the left atrium and pulmonary veins (LA-PVs) to treat atrial fibrillation (AF). This report details the accuracy and utility of an intra procedural means to generate 3-D volumetric renderings of the LA-PV anatomy: contrast-enhanced rotational X-ray angiography (3DRA).
Methods and Results: Preprocedural CT or MR imaging and intraprocedural rotational angiography was performed in 42 patients undergoing AF ablation procedures. Initially, pulmonary artery (PA) bolus-chase contrast injections were performed (20 mL, 20 mL/s) to establish pulmonary transit time and cardiac isocentering. Depending on cardiac size, either a single PA injection (80–100 mL, 20 mL/s) or two separate dedicated left/right PA branch injections were performed (60 mL each, 20 mL/s). For the latter, the two volumes of the left/right portions of the LA-PVs were registered and fused. LA-PV 3DRA images were assessed qualitatively and quantitatively in comparison with CT/MR images. The majority of the 3DRA acquisitions (71%) were deemed at least "useful" in delineating the LA-PV anatomy. The LA appendage was delineated in 57% of the cases. A blinded quantitative comparison of PV ostial diameters resulted in an absolute difference of only 2.7 ± 2.3 mm, 2.2 ± 1.8 mm, 2.4 ± 2.2 mm, and 2.2 ± 2.3 mm for the left-superior, left-inferior, right-superior, and right-inferior PVs, respectively. The feasibility for registering the 3DRA image with real-time electroanatomical mapping was also demonstrated.
Conclusion: Intraprocedural contrast-enhanced rotational angiography provides volumetric 3-D images of the LA-PVs of comparable diagnostic value to dedicated preprocedural CT/MR imaging.     

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.     

左心房容积指数与心房颤动导管消融预后的关系

目的探讨左心房大小与心房颤动(房颤)导管消融术预后的相关性及其评估指标。方法本中心2005年5月至2006年11月行房颤导管消融的连续43例患者,平均年龄60±12岁,男25例(58%);持续房颤5例(12%);CARTO三维标测下行环肺静脉左心房线性消融。二维超声双平面Simpson法测量左心房前后径(LAD)、上下径和左右径及左心室射血分数(LVEF),椭圆公式(Pum-bo法)计算左心房容积(LAV),体表面积(BSA)标化计算左心房容积指数(LAVI)和左心房内径指数(LADI)。消融后3个月评价疗效,单因素和多因素分析年龄、性别、房颤病史、高血压、LAD、LAV、LADI、LAVI、LVEF与房颤导管消融后复发的关系。结果单次消融3个月后15例(34%)患者有复发。复发组与消融治疗有效组LAVI差异有统计学意义(68.19±23.68mL/m2和52.07±17.34mL/m2,P=0.019),复发组LAVI95%CI54.70～80.30mL/m2。而年龄(59.5±12.0岁和60.5±12.0岁,P=0.806)、性别(男/女分别为7/9和18/9,P=0.338)、房颤病史(4.4±4.2年和5.8±5.3年,P=0.46)、高血压患病率(6/15和11/27,P=0.963)、LAD(4.01±0.50cm和3.87±0.50cm,P=0.41)、LADI(0.0476±0.0018和0.0423±0.0020,P=0.093)、LAV(53.92±17.14mL和49.92±16.65mL,P=0.471)、LVEF(69.7%±10.1%和70.2%±11.0%,P=0.91)差异均无统计学意义。Logistic回归分析LAVI与复发的Pearson相关系数r=0.374呈正相关,OR=1.04,95%CI0.99～1.09,P=0.04。结论LAVI评估左心房的大小优于左心房内径、LADI和LAV等参数;LAVI与房颤导管消融术后成功率相关,可预测房颤导管消融术的预后。我们的研究提示,LAVI≥55mL/m2可作为判断房颤导管消融术后复发高危的参考指标。     

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.     

二尖瓣峡部的解剖及射频导管消融

射频导管消融电隔离肺静脉是目前治疗心房颤动（房颤）的主要方法之一。然而单纯电隔离肺静脉的患者中有20％～40％的复发率,为了提高房颤射频导管消融的成功率,在成功电隔离肺静脉后,加左心房关键部位线（如顶部线、二尖瓣峡部线）的消融提高了房颤消融的成功率。     

Effect of pulmonary vein anatomy and left atrial dimensions on outcome of circumferential radiofrequency catheter ablation for atrial fibrillation

Multislice computed tomography (MSCT) is commonly acquired before radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) to plan and guide the procedure. MSCT allows accurate measurement of the left atrial (LA) and pulmonary vein (PV) dimensions and classification of the PV anatomy. The aim of the present study was to investigate the effect of LA dimensions, PV dimensions, and PV anatomy on the outcome of circumferential RFCA for AF. A total of 100 consecutive patients undergoing RFCA for AF (paroxysmal 72%, persistent 28%) were studied. The LA dimensions, PV dimensions, and PV anatomy were evaluated three dimensionally using MSCT. The PV anatomy was classified as normal or atypical according to the absence/presence of a common trunk or additional veins. After a mean follow-up of 11.6 ± 2.8 months, 65 patients (65%) maintained sinus rhythm. The enlargement of the left atrium in the anteroposterior direction on MSCT was related to a greater risk of AF recurrence. No relation was found between the PV dimensions and the outcome of RFCA. In addition, normal right-sided PV anatomy was related to a greater risk of AF recurrence compared to atypical right-sided PV anatomy. Multivariate analysis showed that an anteroposterior LA diameter on MSCT (odds ratio 1.083, p = 0.027) and normal right-sided PV anatomy (odds ratio 6.711, p = 0.006) were independent predictors of AF recurrence after RFCA. In conclusion, enlargement of the anteroposterior LA diameter and the presence of normal anatomy of the right PVs are independent risk factors for AF recurrence. No relation was found between the PV dimensions and outcome of RFCA.     

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.     

导管射频消融电隔离肺静脉治疗局灶性心房颤动一例

导管射频消融治疗起源于肺静脉的局灶性心房颤动 (房颤 )是近年来心律失常介入治疗领域的热点 ,但由于复发率较高以及出现肺静脉狭窄等并发症 ,对其方法学有很大争议。近来我们对 1例局灶性房颤通过射频消融左肺静脉口成功的造成肺静脉与左心房之间的电隔离 ,现报道如下。　　资料和方法　患者男性 ,6 3岁 ,有阵发性心悸病史 10年 ,心电图和动态心电图示频发房性早搏 (房早 ) ,可见“Ｐ在Ｔ上”房早诱发短阵房颤 ,持续数分钟和数小时。平时房颤发作频繁 ,多种抗心律失常药物治疗无效。此次因发作房颤入院。入院诊断 :阵发性房颤 ,冠心病、陈…     

Visualization of catheter ablation for atrial fibrillation: Impact of devices and anatomy

Endocardial access to the left atrium is commonly achieved to treat patients with atrial fibrillation, using different device delivery systems for cardiac ablation. But the large variation in human anatomy presses the limits of existing medical devices. In this unique study, we directly visualized the device-tissue interface in fresh reanimated human hearts using Visible Heart^® methodologies. Our goal was to better understand any opportunities to improve therapeutic approaches. The visual images obtained in this study (also featured in this article) allow a more intimate grasp of the key steps required in various ablation procedures, as well as some limitations of current device designs. These images show the potential risks of conducting transseptal punctures and the difficulties of placing catheter tips in certain scenarios (e.g., when creating circumferential lesions); they also demonstrate potential problems that could occur while attempting to place catheter tips on such anatomies like the mitral isthmus. In our analysis of these images, we focus on where enhancements are needed to refine device functionality.