电解剖标测和磁共振影像融合技术指导导管消融心房颤动的有效性研究

目的探讨三维电解剖标测（CARTO）系统重建图像和预先取得的磁共振影像融合后指导心房颤动（房颤）导管消融的有效性。方法从2005年9月至2006年9月对连续100例药物治疗无效的房颤患者行导管消融治疗,基本策略均为在CARTO系统指导下进行环肺静脉线性消融并实现电学隔离。随机分为2组,每组50例。第1组为术前配准组,在消融开始前即进行影像配准并融合,并在此融合影像指导下进行导管消融,消融结束后进行再次融合;第2组为术后配准组,在单纯CARTO技术指导下消融,消融结束后才进行影像配准并融合。最后比较两组的消融结果并评估消融过程中的差异。结果环肺静脉消融结束后,第1组左心房三维磁共振表面重建影像至电解剖标测图像各点平均距离为（1．6±0．7）mm,消融线上平均标记位点（75±27）个,平均X线透视时间（31±21）min;第2组的上述指标分别为（2．1±1．3）mm、（98±38）个、（55±29）min。以上组间比较差异都有统计学意义。将实际消融线与预定消融线比较,第2组中有组间差异的偏差区域分别是左侧肺静脉前庭顶部（15例）、底部（11例）、前下缘（23例）、前上缘（24例）和右侧肺静脉前庭后上缘（12例）、底部（10例）、前下缘（15例）。结论影像融合技术指导导管消融可提高准确性,并可减少X线透视时间及消融点数。     

Image integration in electroanatomic mapping

Abstract Over the past five years, integration of the pre-procedural MR/CT images with a 3D electroanatomic mapping system has been developed to facilitate catheter ablation of clinical arrhythmias. It presents a significant advantage over the less-detailed surrogate geometry created by the 3D mapping systems. The process of image integration consists of pre-procedural imaging, image segmentation and image registration. Clinical studies have demonstrated the feasibility and accuracy of the use of image integration to guide catheter ablation of atrial fibrillation (AF). Accurate registration of the 3D left atrial MR/CT image to the real-time catheter mapping space can be technically challenging. Several important considerations should be taken into account to minimize registration error. Enhanced ability of catheter navigation with image integration may improve the efficacy and safety of anatomically based ablation strategies such as ablations of AF and nonidiopathic ventricular tachycardia. New developments in the field include integration of pathophysiologic as well as real-time anatomic information to the 3D mapping systems, and the use of new navigation system to improve registration. Drs Dong and Dickfeld are consultants of and received research grants from Biosense Webster Inc.     

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.     

Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the "true anatomy" on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation.

BACKGROUND: Current concepts of catheter ablation for atrial fibrillation (AF) commonly use three-dimensional (3D) reconstructions of the left atrium (LA) for orientation, catheter navigation, and ablation line placement. OBJECTIVES: The purpose of this study was to compare the 3D electroanatomic reconstruction (Carto) of the LA, pulmonary veins (PVs), and esophagus with the true anatomy displayed on multislice computed tomography (CT). METHODS: In this prospective study, 100 patients undergoing AF catheter ablation underwent contrast-enhanced spiral CT scan with barium swallow and subsequent multiplanar and 3D reconstructions. Using Carto, circumferential plus linear LA lesions were placed. The esophagus was tagged and integrated into the Carto map. RESULTS: Compared with the true anatomy on CT, the electroanatomic reconstruction accurately displayed the true distance between the lower PVs; the distances between left upper PV, left lower PV, right lower PV, and center of the esophagus; the longitudinal diameter of the encircling line around the funnel of the left PVs; and the length of the mitral isthmus line. Only the distances between the upper PVs, the distance between the right upper PV and esophagus, and the diameter of the right encircling line were significantly shorter on the electroanatomic reconstructions. Furthermore, electroanatomic tagging of the esophagus reliably visualized the true anatomic relationship to the LA. On multiple tagging and repeated CT scans, the LA and esophagus showed a stable anatomic relationship, without relevant sideward shifting of the esophagus. CONCLUSION: Electroanatomic reconstruction can display with high accuracy the true 3D anatomy of the LA and PVs in most of the regions of interest for AF catheter ablation. In addition, Carto was able to visualize the true anatomic relationship between the esophagus and LA. Both structures showed a stable anatomic relationship on Carto and CT without relevant sideward shifting of the esophagus.     

Intracardiac echo-guided image integration: optimizing strategies for registration

Introduction: Image integration is being used in ablation procedures. However, the success of this approach is dependent on the accuracy of the image integration process. This study aims to evaluate the in vivo accuracy and reliability of the integrated image.
Methods and Results: One hundred twenty-four patients undergoing radiofrequency (RF) ablation catheter ablation for atrial fibrillation (AF) were recruited for this study from three different centers. Cardiac computerized tomography (CT) was performed in all patients and a 3D image of the left atrium (LA) and pulmonary veins (PVs) was extracted for registration after segmentation using a software program (CartoMerge, Biosense Webster, Inc.). Different landmarks were selected for registration and compared. Surface registration was then done and the impact on integration and the landmarks was evaluated.
The best landmark registration was achieved when the posterior points on the pulmonary veins were selected (5.6 ± 3.2). Landmarks taken on the anterior wall, left atrial appendage (LAA) or the coronary sinus (CS) resulted in a larger registration error (9.1 ± 2.5). The mean error for surface registration was 2.17 ± 1.65. However, surface registration resulted in shifting of the initially registered landmark points leading to a larger error (from 5.6 ± 3.2 to 9.2 ± 2.1; 95% CI 4.2–3.05).
Conclusion: Posterior wall landmarks at the PV-LA junction are the most accurate landmarks for image integration in respect to the target ablation area. The concurrent use of the present surface registration algorithm may result in shifting of the initial landmarks with loss of their initial correlation with the area of interest.     

Impact of computed tomography image and contact force technology on catheter ablation for atrial fibrillation

AIM:To investigate the impact of using computed tomography(CT) and contact force(CF) technology on recurrence of atrial tachyarrhythmia after atrial fibrillation(AF) ablation.METHODS: This non-randomized study included 2 groups of patients. All patients had symptomatic recurrent paroxysmal or persistent AF and were treated with at least 1 anti arrhythmic medication or intolerant to medication. The first group included 33 patients who underwent circumferential pulmonary veins isolation(PVI) for AF during 2012 and 2013 guided by CT image integration(Cartomerge, Biosense Webster, Diamond Bar, CA, United States) of left atrium and pulmonary veins into an electroanatomic mapping(EAM) system(CT group) using standard irrigated radiofrequency catheter(Thermo Cool, Carto, Biosense Webster, Diamond Bar, CA, United States) or irrigated catheter with integrated CF sensor(Smart Touch, Carto, Biosense Webster, Diamond Bar, CA, United States). The second group included immediately preceding 32 patients who had circumferential PVI by standard irrigated catheter(Thermo Cool) using only EAM(Carto) system(EAM group). Linear lesions were performed according to the discretion of operator. RESULTS: Sex, age, and persistent AF were not different between groups. PVI was achieved in all patients in both groups. Linear ablations including cavo-tricuspid isthmus and or roof line ablation were not different between groups. Free of atrial tachyarrhythmia during follow-up of 24 mo was significantly higher among CT group compared to EAM group(81% vs 55%; respectively; P = 0.027). When 11 patients from CT group who had ablation using Smart Touch catheter were excluded, the difference between CT group and EAM became non significant(73% vs 55%; respectively; P = 0.16). Sub analysis of CT group showed that patients who had ablation using Smart Touch catheter tend to be more free of atrial tachyarrhythmia compared to patients who had ablation using standard irrigated catheter during follow-up(100% vs 73%; respectively; P = 0.07). Major complications(pericardial effusion, cerebrovascular accident/transient ischemic attack, vascular access injury requiring intervention) did not occurred in both groups.CONCLUSION:These preliminary results suggest that CT image integration and CF technology may reduce the recurrence of atrial tachyarrhythmia after catheter ablation for AF.     

Image‐Integration of Intraprocedural Rotational Angiography‐Based 3D Reconstructions of Left Atrium and Pulmonary Veins into Electroanatomical Mapping: Accuracy of a Novel Modality in Atrial Fibrillation Ablation

DynaCT Cardiac Integration into Electroanatomical Mapping. Introduction: Exact visualization of complex left atrial (LA) anatomy is crucial for safety and success rates when performing catheter ablation of atrial fibrillation (AF). The aim of our study was to validate the accuracy of integrating rotational angiography‐based 3‐dimensional (3D) reconstructions of LA and pulmonary vein (PV) anatomy into an electroanatomical mapping (EAM) system. Methods and Results: In 38 patients (62 ± 8 years, 25 females) undergoing catheter ablation of paroxysmal (n = 19) or persistent (n = 19) AF, intraprocedural rotational angiography of LA and PVs was performed. The subsequent 3D reconstruction and segmentation of LA and PVs was transferred to the EAM system and registered to the EAM. The distances of all EAM points to corresponding points on the LA syngo® DynaCT Cardiac surface were calculated. Segmentation of LA with clear visualization of adjacent structures was possible in all patients. Also, the integrated segmentation of the LA was used to guide the encirclement of ipsilateral veins, which resulted in PV isolation in all patients. Integration into the 3D mapping system was achieved with a distance error of 2.2 ± 0.4 mm when compared with the EAM surface. Subgroups with paroxysmal and persistent AF showed distance errors of 2.3 ± 0.3 mm and 2.1 ± 0.4 mm, respectively (P = n.s.). Conclusion: Intraprocedural registration of LA and PV anatomy by contrast enhanced rotational angiography was feasible and accurate. There were no differences between patients with paroxysmal or persistent AF. Therefore, integration of rotational angiography‐based reconstructions into 3D EAM systems might be helpful to guide catheter ablation for AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 278–283, March 2010)     

Validation of three-dimensional cardiac image integration: use of integrated CT image into electroanatomic mapping system to perform catheter ablation of atrial fibrillation

INTRODUCTION: Accurate visualization of the complex left atrial (LA) anatomy and the location of an ablation catheter within the chamber is important in the success and safety of ablation for atrial fibrillation (AF). We describe the integration of CT into an electroanatomic mapping (EAM) system and its validation in patients undergoing catheter ablation for AF. METHODS AND RESULTS: Thirty patients (59.2 +/- 8 years, 25 M) with paroxysmal (12) and persistent (18) AF underwent ablation using CT image integration into an electroanatomic mapping system. CT registration using the pulmonary veins as markers (landmark) was achieved with an error of 6.4 +/- 2.8 mm with repeat registration required in two patients. Registration of the CT by best fit to a electroanatomic geometry (surface) was achieved with an error of 2.3 +/- 0.4 mm. There was no significant difference in the regional LA registration error at superior (1.7 +/- 0.7 mm), inferior (2.2 +/- 1.4 mm), septal (1.7 +/- 0.8 mm), and lateral (1.7 +/- 0.7 mm, P = 0.13) sites. Cardiac rhythm at the time of CT did not have a significant effect on total or regional surface registration accuracy (mean total 2.5 +/- 0.3 in AF patients vs 2.3 +/- 0.5 in SR patients, P = 0.22). The integrated CT was used to guide the encirclement of the pulmonary veins (PV) in pairs with electrical isolation achieved by maintaining ablation along the ablation line in 58 of 60 PV pairs. Postprocedural PV angiography did not demonstrate significant stenosis. CONCLUSION: CT image integration into an EAM system was successfully performed in patients undergoing catheter ablation for AF. With a greater appreciation of the complex and variable nature of the PV and LA anatomy this new technology may improve the efficacy and safety of the procedure.     

Factors affecting error in integration of electroanatomic mapping with CT and MR imaging during catheter ablation of atrial fibrillation

Objective Integration of 3-D electroanatomic mapping with Computed Tomographic (CT) and Magnetic Resonance (MR) imaging is gaining acceptance to facilitate catheter ablation of atrial fibrillation. This is critically dependent on accurate integration of electroanatomic maps with CT or MR images. We sought to examine the effect of patient- and technique-related factors on integration accuracy of electroanatomic mapping with CT and MR imaging of the left atrium. Materials and methods Sixty-one patients undergoing catheter-based atrial fibrillation (AF) ablation procedures were included. All patients underwent cardiac CT (n = 11) or MR (n = 50) imaging, and image integration with real-time electroanatomic mapping of the aorta and left atrium (LA). CARTO-Merge software (Biosense-Webster) was used to calculate the overall average accuracy of integration of electroanatomic points with the CT and MR-derived reconstructions of the LA and aorta. Results There was a significant correlation between LA size assessed by electroanatomic mapping (112 ± 31 ml) and average integration error (1.9 ± 0.6 mm) (r = 0.46, p = 0.0003). There was also greater integration error for patients with LA volume ≥ 110 ml (n = 31) versus < 110 ml (n = 30) (p = 0.004). In contrast, there was no significant association between average integration error and paroxysmal versus persistent AF, left ventricular ejection fraction, days from imaging to electroanatomic mapping, or images derived from CT versus MR. Conclusions Patients with larger LA volume may be prone to greater error during integration of electroanatomic mapping with CT and MR imaging. Strategies to reduce integration error may therefore be especially useful in patients with large LA volume.     

CARTO标测指导射频消融治疗非峡部依赖性心房扑动的初步研究

初步探讨非峡部依赖性心房扑动 (简称房扑 )———非典型房扑CARTO标测的方法学和射频消融效果。 4例经电生理标测证实的非典型房扑患者 ,男、女各 2例 ,年龄 2 4～ 5 7岁。 1例为先天性心脏病 (简称先心病 )三房心外科术后 ,1例为慢 快综合征。房扑发作时在右房或左房CARTO标测 ,三维重建右房或左房 ,寻找房扑折返径路的关键峡部区域行线性消融。结果 :3例为右房非峡部依赖性房扑 ,1例消融径线为 2条 ,即三尖瓣环至下腔静脉(IVC)口和右房后外侧至IVC ,1例消融径线为右房前中外侧 ,1例为右房下外侧。 1例左房房扑 ,消融径线位于右上肺静脉口下方至卵园窝。 4例均即时消融成功。随访 8～ 2 4个月 ,有 1例先心病术后房扑复发 ,再次行CARTO标测发现房扑折返环位于左房 ,划线消融未成功。结论 :CARTO标测非峡部依赖性房扑有一定的优势 ,能显示房扑折返环和关键峡部 ,并能指导线性消融     

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.     

Safe and Rapid Isolation of Pulmonary Veins Using a Novel Circular Ablation Catheter and Duty-Cycled RF Generator

Background: Ablation of atrial fibrillation (AF) has been one of the most difficult and time-consuming electrophysiological procedures. Due to the rapidly increasing demand for ablation procedures, technical advances would be helpful to reduce complexity and procedure time in AF ablation. Therefore, we investigated the feasibility of a single-catheter technique for pulmonary vein (PV) isolation utilizing a decapolar catheter combined with a duty-cycled, unipolar–bipolar radiofrequency (RF) generator.
Methods: AF mapping and ablation was performed in 21 consecutive patients (mean age 59 ± 12 years, 9 males) with paroxysmal AF (n = 17) and persistent AF (n = 4). The ablation catheter was forwarded to the LA via single-transseptal puncture. All electrodes were energized in 2 to 5 applications per vein, followed by segmental RF applications, as needed, to achieve electrical isolation. To assess left atrial anatomy for purposes of catheter manipulation, and later evaluate the possibility of asymptomatic PV-stenosis, CT or MR imaging was performed both prior to ablation and at 6-month follow-up.
Results: Isolation could be achieved in 85/86 veins (99%). Procedure time for ablation was 81 ± 13 minutes, and fluoroscopy time was 30 ± 11 minutes. There were no procedural complications. Success rate at 6 months was 86% (18/21). MR or CT imaging excluded asymptomatic PV-stenosis.
Conclusion: Mapping and ablation of PVs can be performed in a safe and efficient manner using a single-catheter technique, with short procedure times and minimal learning curve. Thus, this system may be of high interest not only for high volume but all centers performing AF ablation.     

CARTO系统指导下食管三维重建法在心房颤动线性消融术中的应用价值

对1例持续性心房颤动的患者行左房线性消融,采用CARTO系统行左房三维电解剖标测的同时行食管解剖重建。结果:在左房解剖模式图左房后壁上清晰显示食管的走行及和心房的相对位置,在此指导下,设计环形消融径线时可尽量避开食管的位置,术中和术后随访2个月无并发症发生。结论:食管三维重建法有利于预防心房颤动消融术引起的心房食管瘘形成,且简单易行,值得临床进一步应用。     

Feasibility and validation of registration of three-dimensional left atrial models derived from computed tomography with a noncontact cardiac mapping system.

OBJECTIVES: The purpose of this study was to determine the feasibility and assess the validity of registering three-dimensional (3D) models from computed tomographic (CT) images using a cardiac mapping system. BACKGROUND: Registration of 3D anatomic models with an interventional system could help identify and navigate mapping and ablation catheters over a complex structure such as the left atrium (LA). METHODS: ECG-gated, contrast-enhanced cardiac CT imaging was performed in 14 patients with atrial fibrillation. Segmentation was used to create 3D models of the LA. The 3D models were registered with the mapping system using a series of fiducial points. Registration was accomplished retrospectively in the first 10 patients, and catheter navigation was visualized from recorded data. In the final four patients, registration was accomplished in real time during electrophysiologic study. The mapping catheter position, as it was navigated inside the LA, was applied to the registered model in real time. For the validation study, temporary pacing leads were implanted in the LA of 10 dogs. Following this, CT scanning, segmentation, LA model importation, and registration was described previously. After registration, a mapping catheter was positioned at the site of each buried lead according to the registered model with no fluoroscopic guidance. A radiofrequency lesion was created at this location, and the dog was sacrificed, the heart removed and stained, and the distance between the buried lead and the lesion measured. RESULTS: During the feasibility study, the location of the catheter in the registered model correlated with fluoroscopy, angiography, and intracardiac electrograms. LA endocardial potentials during sinus rhythm and any premature atrial contractions also were successfully delineated over the registered models. In the validation study, the mean target registration error was 2.0 +/- 3.6 mm. CONCLUSIONS: Registration of CT-derived 3D models of the LA using a cardiac mapping system is feasible and accurate.     

肺静脉电传导恢复在外科导管迷宫术后房性心律失常中的作用

目的评估心房颤动（房颤）经外科导管迷宫术后复发房性心律失常经双Lasso导管技术行肺静脉完全电隔离后的疗效。方法在三维电解剖系统指导（Carto）下结合双lasso导管同侧肺静脉标测技术下行经皮射频导管消融术完成。消融术终点：（1）明确同侧肺静脉传导的缝隙并消融致所有肺静脉电位的消失;（2）临床房性心律失常不能诱发。结果对8例经外科导管迷宫术后药物仍无法控制的症状性房颤患者进行了经皮导管射频消融术,男性4例,女性4例,年龄（62±5）岁,左心房内径（50±6）mm,病史时间（9．1±6.3）年。7例患者经双lasso导管技术证实存在肺静脉传导恢复。其中3例患者进行了2次导管消融术,1例患者进行了3次导管消融术。平均随访（5．9±47）个月,7例患者无房颤复发。无消融术相关并发症发生。结论外科迷宫术后房性心律失常复发与术中肺静脉未完全电隔离和肺静脉传导恢复相关。三维电解剖标测系统指导下应用双lasso导管技术行同侧肺静脉完全电隔离能使大部分病例维持窦性心律。     

The impact of respiration on left atrial and pulmonary venous anatomy: Implications for image-guided intervention

BACKGROUND: Image-guided intervention using pre-acquired CT/MR 3-dimensional images is an emerging strategy for atrial fibrillation (AF) ablation but may be limited by its use of static images to depict dynamic physiology. The effect of biologic factors such as respiration on the left atrial-pulmonary venous (LA-PV) anatomy is not well understood but is likely to have important implications. Conventional CT/MR imaging is performed during an inspiratory breath-hold, while electroanatomical mapping (EAM) during "quiet" breathing approximates an expiratory breath-hold. This study examined the effects of respiration on LA-PV anatomy and the error introduced by respiration on the integration of EAM with 3D MR imaging. METHODS: Pre-procedural MRI angiography was performed at both end-expiration (EXP) and end-inspiration (INSP) in 20 patients undergoing AF catheter ablation. 3D INSP and EXP surface reconstructions of the LA-PVs were compared. In selected pts, EAM data acquired during the ablation procedure (n=7) were integrated with the 3D MRI datasets. RESULTS: Qualitative assessment of the INSP and EXP 3D images revealed splaying of the PVs and reduction in PV caliber of the right-sided PVs during held inspiration. After aligning these two datasets, the average surface-to-surface distance calculated by region ranged from 1.99mm (right middle PV) to 3.79mm (left superior PV). Registration of the EAM to the MRI models was better for the EXP dataset (2.30+/-0.73mm) than the INSP dataset (3.03+/-0.57mm; p=0.004). CONCLUSION: There are significant changes in LA-PV anatomy with respiration. MR images acquired during standard held inspiration may introduce unnecessary errors in registration during image-guided intervention.     

Feasibility study of endocardial mapping of ganglionated plexuses during catheter ablation of atrial fibrillation.

BACKGROUND: Numerous reports have demonstrated an association between autonomic tone and atrial fibrillation (AF). Pulmonary vein (PV) denervation during catheter ablation of AF has been shown to significantly reduce recurrence of AF. OBJECTIVES: The purpose of this study was to assess the safety and efficacy of high-frequency stimulation at mapping cardiac ganglionated plexuses in patients undergoing catheter ablation of AF. METHODS: Fourteen patients with a history of symptomatic AF underwent a single transseptal approach and electroanatomic mapping of the left atrium, right atrium, and coronary sinus. Using high-frequency stimulation with patients under general anesthesia (20-50 Hz, 5-15 V, pulse width 10 ms), mapping of ganglionated plexuses was performed. Radiofrequency (RF) ablation was performed during AF guided by complex fractionated atrial electrograms. Lesions were mostly delivered circumferentially in the antral area of the PVs, predominantly over and adjacent to regions of ganglionated plexuses. RESULTS: There was a mean of 4 +/- 1 (range 2-6) ganglionated plexuses per patient, and a mean total of 3 +/- 1 RF applications were delivered over positive vagal sites. Although a vagal response occurred infrequently during ablation (0.9%), postablation high-frequency stimulation failed to provoke a vagal response in 30 (88%) of 34 previously positive vagal sites that underwent ablation. CONCLUSION: Ganglionated plexuses can be precisely mapped using high-frequency stimulation and are located predominantly in the path of lesions delivered during ablation of AF. Objective documentation of modification of autonomic tone can be documented in the majority of patients. Future studies are required to determine the specific role of mapping and targeting of ganglionated plexuses in patients undergoing catheter ablation of AF.     

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.     

Evaluation of 3D guided electroanatomic mapping for ablation of atrial fibrillation in reference to CT-Scan image integration

Background  Anatomical guided atrial fibrillation (AF) catheter ablation relies on the assumption that the left atrium reconstruction anatomy (LARA) using a 3D mapping system precisely matches the patient’s CT scan anatomy (real anatomy). This study investigates whether this postulation is accurate using CT scan image integration. Patients and methods  Thirty consecutive patients (23 men, mean age = 51.9 ± 9.9 years) with symptomatic drug-refractory paroxysmal (n = 21) or persistent (n = 9) AF underwent a circumferential, 2 × 2, pulmonary vein (PV) radiofrequency (RF) ablation using the CARTOMERGE system. Left atrium (LA) anatomy was first reconstructed and RF design lines drawn on this LARA. After a CT-scan image of the LA was integrated into the 3D system, RF lesions were deployed 10 ± 5 mm outside the PV ostia (PVO) onto the CT-scan LA surface. The match between the actual RF lines and the RF design lines was analyzed off-line after catheter withdrawal. Results  Circumferential RF design lines were divided into four segments encircling both the right and left PVs. Design segments matched the actual RF segments in a proportion varying from 23% up to 83%. A mean of 2.8 ± 1.6 segments per patient were inaccurately designed that extended a mean of 3.8 ± 2.3mm inside the adjacent PV or 6.7 ± 1.8mm inside the left atrial appendage (LAA). Seven patients (23%) had four or more segments incorrectly designed. Conclusions  Our study reveals the inaccuracy of 3D anatomic guided RF ablation with respect to the LA anatomical structures that could be possibly improved when combined with CT-scan image integration.     

Compression of the left atrium by the thoracic aorta in patients undergoing pulmonary vein isolation procedure for atrial fibrillation

Introduction With the increasing use of pre-procedural imaging techniques such as magnetic resonance imaging (MRI) and their integration with electroanatomic mapping systems in catheter ablation for atrial fibrillation (AF), atypical anatomy of the pulmonary veins (PV), left atrium (LA) and their relationship to the thoracic aorta is increasingly recognized. Objective To characterize atypical LA-PV anatomies revealed by pre-procedural MRI and their impact on the safety and efficacy of AF ablation procedures. Materials and methods We reported four patients who underwent AF ablation in our electrophysiology laboratory within the last year who had atypical LA-PV anatomy due to aorta compression recognized by pre-procedural three-dimensional (3D) MRI and anatomic segmentation. Twelve matched control cases without aorta compression were selected for comparison of LA-PV measurements. Results All four patients in this study had a normal-sized descending thoracic aorta that compressed the left atrium, and all patients had evidence of left inferior PV narrowing secondary to external compression. Two patients also had anterior LA compression leading to posteriorly displaced interatrial septum. Isolation was not achieved in some PVs due to anatomic restraints, concern regarding risks of aortic injury and worsening pulmonary vein stenosis. There were no immediate or short-term complications. Conclusions Extrinsic compression by the descending aorta on the LA and PV leading to LA compression and/or preexisting PV stenosis is uncommon but has potentially important implications on the overall safety and efficacy of AF ablation procedures. Pre-procedural imaging plays an important role in assessing such anatomic variations and planning of the procedures in order to minimize the risk of PV stenosis and aortic injury.