Evaluation of left atrial and posterior mediastinal anatomy by multidetector helical computed tomography imaging: Relevance to ablation

Introduction Increasing use of catheter ablation in the left atrium (LA) requires understanding of substrate anatomy, especially with regard to potential damage to adjacent structures. Methods and results We reviewed multidetector helical computed tomography (MDCT) imaging on 42 subjects, 26 imaged before planned LA ablation for atrial fibrillation (AF), and 16 without AF. LA volume and dimensions were larger in patients with AF (p < 0.05) and the spine and aorta (Ao) impressed the LA more frequently in the AF group. The esophagus (Eo) was the predominant feature on the posterior LA wall, contacting it in all patients. The Ao was in contact with the LA body or the left inferior pulmonary vein (PV) in 32 (76%) of 42 cases, and in 10 it ran along an indentation on the posterior aspect of the LA. The coronary sinus was adjacent to LA ablation sites, the azygos vein was rarely adjacent to those sites, and the left bronchus abutted the PV ostium but not the LA. Two patients had findings that directly impacted the ablation procedure: one patient had a dilated fluid filled Eo with esophageal stricture and underwent nasogastric decompression before ablation, and one was discovered to have an anomalous PV and underwent surgical repair. Conclusions MDCT imaging identifies structures adjacent to the LA, which could be affected by ablation. Posterior LA topography can be influenced by the position of the Ao or by the proximity of the spine. Preprocedural imaging can characterize anatomic structures that could be vulnerable during ablation, and detect unusual pathology that can affect the treatment plan.     

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.     

Dilated left atrium and pulmonary veins in patients with calcified coronary artery: a potential contributor to the genesis of atrial fibrillation

Introduction: Coronary artery disease (CAD) is an important etiology of atrial fibrillation (AF). Coronary artery calcification is a marker of coronary atherosclerosis and coronary events. The purpose of this study was to investigate whether larger left atrium (LA) and pulmonary veins (PVs) were seen by multidetector computed tomography (MDCT) scans in those patients with higher coronary calcium scores.
Methods and Results: A total of 166 patients undergoing MDCT for general check-up (n = 128, 77%) or suspected CAD (n = 38, 23%) were enrolled and divided into a control (calcium score = 0, n = 60), medium calcium score (calcium score = 100∼400, n = 47), and high calcium score (calcium score >400, n = 59) groups. Diameters and areas of the LA, left atrial appendage (LAA), and PVs were measured by MDCT. The high calcium score group had significantly larger PVs diameters, LAA orifice area (1.9 ± 1.4 cm², 0.9 ± 0.5 cm², 0.8 ± 0.4 cm², P < 0.005), LA anterior-posterior distance (32.2 ± 6.8 mm, 30.4 ± 6.5 mm, 27.3 ± 6.0 mm, P < 0.05), and transverse distance (52.6 ± 7.3 mm, 50.2 ± 9 mm, 49.5 ± 4.6 mm, P < 0.05) than the medium calcium score and control groups. Six (3.6%) patients with paroxysmal AF had higher calcium scores and larger diameters of LA, LAA, and PVs than those (96.4%) without paroxysmal AF. Two patients in the high calcium score group had calcified PVs localized to the right upper and left upper PVs. The incidence of calcified PVs was 1.2% for the total patients and 3.3% for the high calcium score patients.
Conclusion: In the presence of high calcium scores in this patient population, the LA, LAA, and PVs were enlarged.     

Left atrial thickness under the catheter ablation lines in patients with paroxysmal atrial fibrillation: insights from 64-slice multidetector computed tomography

A detailed understanding of the left atrial (LA) anatomy in patients with atrial fibrillation (AF) would improve the safety and efficacy of the radiofrequency catheter ablation. The objective of this study was to examine the myocardial thickness under the lines of the circumferential pulmonary vein isolation (CPVI) using 64-slice multidetector computed tomography (MDCT). Fifty-four consecutive symptomatic drug-refractory paroxysmal AF patients (45 men, age 61 ± 12 years) who underwent a primary CPVI guided by a three-dimensional electroanatomic mapping system (Carto XP; Biosense-Webster, Diamond Bar, CA, USA) with CT integration (Cartomerge; Biosense-Webster) were enrolled. Using MDCT, we examined the myocardial thickness of the LA and pulmonary vein (PV) regions in all patients. An analysis of the measurements by the MDCT revealed that the LA wall was thickest in the left lateral ridge (LLR; 4.42 ± 1.28 mm) and thinnest in the left inferior pulmonary vein wall (1.68 ± 0.27 mm). On the other hand, the thickness of the posterior wall in the cases with contact between the esophagus and left PV antrum was 1.79 ± 0.22 mm (n = 30). After the primary CPVI, the freedom from AF without any drugs during a 1-year follow-up period was 78 % (n = 42). According to the multivariate analysis, the thickness of the LLR was an independent positive predictor of an AF recurrence (P = 0.041). The structure of the left atrium and PVs exhibited a variety of myocardial thicknesses in the different regions. Of those, only the measurement of the LLR thickness was associated with an AF recurrence.     

心房颤动患者食管与左心房形态学关系的多层螺旋计算机断层摄影术研究

目的应用多层螺旋计算机断层摄影术（MSCT）探讨心房颤动（房颤）患者食管与左心房形态学的关系。方法房颤射频消融术前行多层螺旋计算机断层摄影术肺静脉成像的患者,共收取左心房图像质量最佳者100例[其中男性60例,女性40例,平均年龄：38—75（55．5±10．0）岁],应用三维重建及多平面技术;测量食管与左心房的位置走形,食管与各肺静脉口的距离,观察食管与左心房间脂肪垫的连续性,食管与左心房紧密接触部（该处无脂肪垫）的位置,测量该接触位置的平均长度及宽度,测量左心房的直径。结果91％的食管位于左心房后壁中线偏左侧,其中的65％平行于左上及左下肺静脉口;26％呈从右上向左下方斜行。食管与各肺静脉口的距离0～50．8mm,其中48％的食管距左上肺静脉口的距离〈5mm。95％的食管与左心房间可见脂肪垫,其中96％呈间断性。食管与左心房紧密接触部位以左下肺静脉处最多见（占75％）。食管与左心房后壁接触的平均长度6．5—66．0（40．2±9．6）mm;平均宽度3．5～23．0（15．1±1．6）mm。食管的平均宽度15．7—24．9（20．2±4．7）mm。左心房的直径：上下径（45±3）mm;前后径（54±4）mm。结论在房颤患者中,食管与左心房及肺静脉间的解剖关系变化很大。大多数患者食管距左肺静脉最近;食管与左心房紧密接触部的位置以左下肺静脉处最多见（占75％）,在房颤射频消融术前行MSCT可以很好地显示食管与左心房间的形态解剖,对于防止食管损伤很重要。     

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.     

Mechanisms of recurrent atrial fibrillation: comparisons between segmental ostial versus circumferential pulmonary vein isolation

Background: Electrical isolation of pulmonary veins (PVs) is an effective therapy for atrial fibrillation (AF). Both segmental ostial PV ablation and circumferential ablation with PV–left atrial (LA) block have been implicated to eliminate AF. However, the mechanism of the recurrent AF after undergoing either strategy remains unclear.
Methods and Results: Of the 73 consecutive patients with symptomatic AF that underwent PV isolation and had recurrences of AF, Group 1 consisted of 46 patients (age 56 ± 13 years old, 35 males) who underwent PV isolation by segmental ostial PV ablation and Group 2 consisted of 27 patients (age 51 ± 11 years old, 24 males) who underwent circumferential ablation with PV–LA block. In Group 1, the earliest ectopic beat or ostial PV potentials were targeted. In Group 2, circumferential ablation with PV–LA block was performed by encircling the extraostial regions around the left and right PVs. During the first procedure, all patients had PV–AF. There was no difference in the non-PV ectopy between Group 1 and Group 2. During the second procedure, the incidence of an LA posterior wall ectopy initiating AF was significantly lower (20% vs. 0%, P = 0.01) in Group 2. There was no difference in the PV ectopy initiating AF during the second procedure.
Conclusion: Circumferential ablation of AF with PV–LA block may eliminate the LA posterior wall ectopy and decrease the incidence of LA posterior wall ectopy initiating AF during the second procedure.     

Further evidence of a close anatomical relation between the oesophagus and pulmonary veins.

BACKGROUND: Atrio-oesophageal fistula has been reported as a rare but life-threatening complication of ablation of atrial fibrillation (AF). Therefore, the position of the oesophagus in relation to the left atrium (LA) is of major importance for AF ablation. METHODS AND RESULTS: In order to investigate the possible anatomical variability between the oesophagus and the left atrium, multidetector-row spiral computed tomography (MDCT) of 60 healthy males (age 58.1+/-5.1 years; LA diameter 5.4+/-0.7 x 3.8+/-0.6 cm; LA volume 60.5+/-15.4 ml) was analyzed. The distance between the oesophagus and the ostia of the pulmonary veins (PV) ranged between 0 and 50.7 mm. Especially for the left PV, the oesophagus was closer than 5 mm to the ostia in 29 cases (48%; n = 24 for left superior PV; n = 10 for left inferior PV; n = 0 for right superior PV; n = 1 for right inferior PV). In addition, the oesophagus was very close to the LA wall (0.8+/-0.9 mm; range 0-3.3 mm). Intraobserver variability was 1.1+/-0.7 mm or 3.5%. CONCLUSION: The position of the oesophagus in relation to the LA and the PV demonstrates high variability. In many cases, the oesophagus is very close to the ostia of the PVs and lies only a short distance from the LA wall. Thus, an anatomical localization of the oesophagus may be critical before or during AF ablation to prevent atrio-oesophageal fistula, especially as there is a need for transmural atrial lesions.     

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.     

Randomized comparison of encircling and nonencircling left atrial ablation for chronic atrial fibrillation

BACKGROUND: Left atrial (LA) circumferential ablation has been reported to eliminate atrial fibrillation (AF). Whether an ablation without encirclement of the pulmonary veins (PVs) is as effective as LA circumferential ablation is not clear. OBJECTIVES: The purpose of this study was to compare the efficacy of LA circumferential ablation and nonencircling linear ablation in patients with chronic AF. METHODS: Eighty patients with chronic AF were randomized to undergo LA circumferential ablation (n = 40) or nonencircling linear ablation (n = 40). In LA circumferential ablation, the PVs were encircled, with additional lines made in the mitral isthmus and posterior wall or roof. In nonencircling linear ablation, 4 +/- 1 ablation lines were created through areas of complex electrograms, with lines in the roof (38), anterior wall (36), septum (40), mitral isthmus (32), and posterior annulus (6). The endpoint of LA circumferential ablation and nonencircling linear ablation was voltage abatement. RESULTS: LA flutter occurred in 15% after LA circumferential ablation and in 18% after nonencircling linear ablation (P = .8). A repeat ablation procedure was performed for recurrent AF in 7 and 11 patients or for atrial flutter in 6 and 4 patients after LA circumferential ablation and nonencircling linear ablation, respectively (P = .8). At 9 +/- 4 months, the prevalence of AF was 28% in the LA circumferential ablation and 25% in the nonencircling linear ablation group (P = .8). Sixty-eight percent and 60% of patients were in sinus rhythm and free of AF and atrial flutter in the absence of antiarrhythmic drug therapy after LA circumferential ablation and nonencircling linear ablation, respectively (P = .5). There were no complications. CONCLUSION: Nonencircling linear ablation and LA circumferential ablation are equally efficacious in eliminating chronic AF. However, the advantage of nonencircling linear ablation is that it eliminates the need for ablation along the posterior wall of the LA. Therefore, nonencircling linear ablation may avoid the small but real risk of atrioesophageal fistula formation associated with LA circumferential ablation.     

Morphologic remodeling of pulmonary veins and left atrium after catheter ablation of atrial fibrillation: insight from long-term follow-up of three-dimensional magnetic resonance imaging

INTRODUCTION: Understanding the structural remodeling and reverse remodeling of the left atrium (LA) and pulmonary vein (PV) after radiofrequency ablation of atrial fibrillation (AF) may provide important insights into the mechanism and management of AF. This study used magnetic resonance angiographic (MRA) images to investigate changes in PV and LA morphologies before and more than 1 year after ablation. METHOD AND RESULTS: Forty-five patients (36 men and 9 women, mean age 60 +/- 13 years) who underwent MRA before and more than 12 months (mean 21 +/- 11) after ablation of paroxysmal AF were included in the study. The patients were divided into two groups: group I included 35 patients without AF recurrence, and group II included 10 patients with late (>1 month postablation) recurrence of AF. The sizes of the LA and nonablated PV were compared before and after ablation. In group I, significant reduction of ostial area of both superior PVs was noted (left superior PV: from 2.85 +/- 0.67 to 2.59 +/- 0.73 cm2; right superior PV: from 2.89 +/- 0.85 to 2.60 +/- 0.73 cm2, both P <0.001). Geometric alteration toward a round shape was noted in the ostia of superior PVs during follow-up (eccentricity of right superior PV and left superior PV decreased from 0.31 +/- 0.10 to 0.22 +/- 0.13 and from 0.27 +/- 0.11 to 0.19 +/- 0.13, respectively, both P <0.01). However, LA volume showed only borderline reduction (from 61.52 +/- 19.06 to 56.64 +/- 17.13 mL, P=0.05). In group II, significant dilation of the LA (from 61.14 +/- 17.54 to 78.73 +/- 25.27 mL, P=0.004) and right superior PV (from 3.41 +/- 1.12 to 4.08 +/- 1.31 cm2, P=0.016) was noted during follow-up. Ostial area and eccentricity of the left superior, left inferior, and right inferior PVs and LA were similar before and after ablation. CONCLUSION: Structural remodeling of the superior PVs and LA can be reversible after successful ablation without AF recurrence; however, late recurrence of AF is associated with progressive LA dilation.     

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.     

Characterization of left atrium and distal pulmonary vein morphology using multidimensional computed tomography

OBJECTIVES: This study was designed to examine the dimensions and morphology of left atrial (LA) and distal pulmonary veins (PVs) using multidetector helical computed tomography (MDCT). BACKGROUND: Detailed knowledge of LA and PV anatomy will assist in the development of techniques for ablative intervention. Multidetector helical computed tomography is a method for multidimensional imaging of cardiac anatomy. METHODS: Multidetector helical computed tomography was used to image the LA and PVs in 70 subjects with and 47 subjects without atrial fibrillation (AF). Accuracy of the MDCT data was confirmed by correlation with echocardiography and endocardial electrogram recordings. RESULTS: Left atrial and PV dimensions were significantly larger in AF versus non-AF subjects, men versus women, and subjects with persistent versus paroxysmal AF. There were no differences between groups in morphologic detail. CONCLUSIONS: Multidetector helical computed tomography images of the LA and PVs are accurate and provide detailed anatomic information. Significant differences in dimensions but not morphologic detail were apparent between groups.     

Close relationship between the bronchi and pulmonary veins: implications for the prevention of atriobronchial fistula after atrial fibrillation ablation

Introduction: Atrio-bronchial fistula (ABF) can be a rare but potentially lethal complication following the catheter ablation of atrial fibrillation (AF). Understanding the extent of the contact between the bronchial tree and pulmonary veins (PVs) is critical to avoid this complication. We investigated the anatomic relationship between the four PVs and bronchial tree using multi-detector computed tomography (MDCT) images.
Methods and Results: Seventy patients with drug refractory AF were included. They underwent 16-slice MDCT before the ablation. The spatial relationship between the bronchus and PVs was demonstrated by the multi-planar images. The bronchus was in direct contact with four PVs in the vast majority of patients. The mean distances between the bronchus and the ostia of right superior, left superior, right inferior, and left inferior PV were 7.1 ± 5.5, 3.5 ± 4.8, 12.3 ± 5.6, and 17.9 ± 6.8 mm, respectively. Patients were categorized into two groups: Group I: proximal contact (<5 mm from the PV ostium) and Group II: distal contact (>5 mm from the PV ostium). For the right superior pulmonary vein (RSPV), the Group I patients were associated with thinner connective tissue between them (P = 0.001), a larger RSPV (17.2 ± 2.2 vs 15.5 ± 2.1 mm, P < 0.001), and right inferior pulmonary vein (RIPV) diameter (15.9 ± 1.9 vs 14.6 ± 1.6 mm, P < 0.01). For the left superior pulmonary vein (LSPV), the Group I patients were associated with an older age (P = 0.02).
Conclusion: Isolation of the superior PVs may carry the potential risk of bronchial damage. The clinical or anatomic characteristics associated with the proximal contact between the bronchi and superior PVs can provide useful information to prevent this complication.     

A new approach for complete isolation of the posterior left atrium including pulmonary veins for atrial fibrillation

Introduction: Esophageal injury is a potential complication after catheter ablation of the posterior left atrium (LA). Therefore, we describe a new approach for complete isolation of the posterior LA including all pulmonary veins (PVs) without vertical lesions along the esophageal aspect of the posterior LA, namely Box isolation .
Methods and Results: Ninety-one patients with paroxysmal atrial fibrillation (AF) underwent Box isolation. Continuous lesions at the anterior portions of the ipsilateral PVs were initially created and then linear ablation of LA roof and bottom was performed to isolate the posterior LA. Continuous vertical lesions at the posterior portions of PVs along the esophageal aspect of the posterior LA were not created. Ablation was performed with an 8-mm-tip catheter. The endpoint was the absence of electrical activity and the inability to pace the posterior LA and all PVs in sinus rhythm. Complete isolation of the posterior LA was achieved in 82 patients (90%). Ablation resulted in the termination of AF in 65%, and subsequent noninducibility of AF in 71% of the patients. A repeat ablation was performed in six of nine patients with recurrence of arrhythmia. At 13 ± 3 months of follow-up, 86 patients (95%) were arrhythmia-free without antiarrhythmic drugs.
Conclusion: This study shows that it is possible to achieve complete isolation of the posterior LA including all PVs without posterior vertical lesions. Box isolation is associated with a high clinical success rate.     

Pulmonary vein isolation and left atrial catheter ablation using a three-dimensional navigation system for the treatment of atrial fibrillation

BACKGROUND:

Atrial fibrillation (AF) is often triggered by ectopic foci originating from pulmonary veins (PVs), with the posterior left atrium (LA) comprising part of the substrate for maintenance. Catheter ablation strategies targeting PVs and the posterior LA may be further refined by incorporating technology beyond standard fluoroscopy.

OBJECTIVES:

To prospectively assess the usefulness of a navigation system to guide a radiofrequency catheter ablation strategy, combining PV isolation (PVI) with anatomical LA ablation.

METHODS:

Sixty-four patients (51 men; mean [± SD] age 52±8 years) who were referred for catheter ablation of paroxysmal (n=49) or persistent (n=15) AF underwent this ablation strategy using the NavX system (Endocardial Solutions Inc, USA). Electrical PVI was guided by a circular mapping catheter. Anatomical ablation consisted of lines drawn along the posterior aspect of the LA from the superior PVs to the inferior PVs. NavX was used for the construction of three-dimensional LA and PV maps with projection of mapping and ablation catheters on the image in real time and for tracking of lesions during posterior LA ablation.

RESULTS:

Electrical PVI was achieved in 100% of procedures and all patients underwent the linear posterior LA ablation described above. Procedural and fluoroscopy times were 188±41 min and 60±12 min, respectively. Repeat procedures for AF recurrence were required in 38 (59%) patients. After a mean follow-up period of 16±10 months, 59 (92%) patients remained arrhythmia-free, including 52 (81%) without antiarrhythmic drugs.

CONCLUSIONS:

An AF ablation strategy that combines nonfluoroscopic visualization of catheters with electrical PVI and anatomical LA ablation is feasible, safe and effective, but often requires repeat procedures.     

Real-Time Rotational ICE Imaging of the Relationship of the Ablation Catheter Tip and the Esophagus During Atrial Fibrillation Ablation

Introduction: Atrioesophageal fistula is a rare complication of atrial fibrillation (AF) ablation that should be avoided. We investigated whether rotational intracardiac echocardiography (ICE) can help to minimize ablation close to the esophagus.
Methods and Results: We studied 41 patients referred for catheter ablation of refractory AF. A rotational ICE catheter was inserted into the (LA) to determine the location of the esophagus. The esophagus was identified to be either adjacent to the pulmonary vein (PV) ostium or to a cuff 2 cm outside the ostium. Circumferential ablation was performed at the PV ostium, with the exact ablation location determined by ICE. The relationship of the catheter tip to the esophagus was imaged during energy delivery, allowing interruption when respiration moved the tip closer to the esophagus. Out of 41 patients, the esophagus was seen near left-sided PVs in 32 and near right-sided PVs in three patients. The median distance from LA endocardium to esophagus was 2.2 mm (range, 1.4–6 mm). In 21 of 35 patients with a closely related esophagus, ablation over the esophagus was avoided by ablating either lateral or medial to the esophagus. In 14 patients, the esophagus could not be avoided, and risk was minimized by limiting lesion size. Significant movement (>10 mm) of the esophagus during the procedure occurred in 3/41 cases.
Conclusion: Rotational ICE can accurately determine the distance of ablation sites from the esophagus. Real-time imaging of the relationship of the ablation catheter tip to the esophagus may reduce the incidence of esophageal injury.     

Complex anatomy surrounding the left atrial posterior wall: analysis with 3D computed tomography

Few studies have explored the topographic anatomy of the esophagus, posterior wall of the left atrium (LA), or fat pads using multidetector computed tomography (MDCT) to prevent the risk of esophageal injury during atrial fibrillation (AF) ablation. MDCT was performed in 110 consecutive patients with paroxysmal or persistent AF before the ablation procedure to understand the anatomic relationship of the esophagus. Two major types of esophagus routes were demonstrated. Leftward (type A) and rightward (type B) routes were found in 90 and 10% of the patients, respectively. A type A route had a larger mean size of the LA than type B. The fat pad was identifiable at the level of the inferior pulmonary vein in 91% of the patients without any predominance of either type. The thickness of the fat pad was thinner in the patients with a dilated LA (>42?mm) than in those with a normal LA size (??42?mm) (p?=?0.01). The results demonstrated that the majority of cases had a leftward route of the esophagus. There was a close association between the LA dilatation and fat pad thinning. With a dilated LA, the esophagus may become easily susceptible to direct thermal injury during AF ablation. Visualization of the anatomic relationship may contribute to the prevention of the potential risk of an esophageal injury.     

旋转式左心房造影在心房颤动消融中的应用

目的 实时了解左心房和肺静脉的解剖结构在导管消融治疗心房颤动(房颤)中起着重要作用.通过腺苷造成完全性房室阻滞,应用旋转式造影的方法进行左心房和肺静脉的实时显像,指导房颤的消融.方法 对70例房颤患者行经导管消融术,全部患者消融术前进行64排CT扫描,且进行左心房的三维重建.房间隔穿刺后,静脉注射腺苷(30 mg)造成完全性房室阻滞,同时向左心房内注射造影剂,进行旋转式左心房造影(右前斜55°～左前斜55.).对造影结果进行定性和定量分析,并与CT相关资料进行对比.结果 65例(94%)1次造影成功,5例(6%)给予腺苷40 mg后,2次造影成功.70例(100%)的4支肺静脉和左心耳嵴可以清晰显像.5支左侧共干和3支附加肺静脉(2支右侧中肺静脉和1支心房顶部肺静脉)在旋转式造影中清晰显像.旋转造影显像和CT图像肺静脉口直径之间有着良好的相关性(r＞0.9).无腺苷相关的严重并发症发生.结论 通过腺苷造成完全性房室阻滞,进行旋转式左心房造影是安全可行的.该方法可以充分显示左心房和肺静脉的解剖结构,指导房颤的导管消融治疗.     

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.