Assessment of pulmonary vein anatomic variability by magnetic resonance imaging: implications for catheter ablation techniques for atrial fibrillation

INTRODUCTION: Pulmonary vein (PV) isolation for atrial fibrillation (AF) currently is performed using either an ostial or an extra-ostial approach. The objective of this study was to analyze by three-dimensional (3D) magnetic resonance angiography (MRA) the anatomy of the PVs in order to detect structural variability that would impact the choice of ablation approach. METHODS AND RESULTS: Three-dimensional MRA was performed in 105 patients undergoing PV isolation. The ostial diameter, branching pattern, and PV angulation were analyzed. Fifty-nine (56%) patients had the typical pattern of 4 PVs with 4 separate ostia, 30 (29%) patients had an additional PV, and 18 (17%) patients had a left common PV trunk. In two patients, there were three right-sided veins and a common left-sided trunk, giving rise to four ostia: three on the right and one on the left. Two different populations of right middle PVs were noted: one where the additional vein projected anteriorly to drain the right middle lobe and one posterior to drain the superior portion of the right lower lobe. The average intrapatient variability in PV diameter was 7.9 +/- 4.2 mm. The PV ostium was <10 mm in 26 (25%) patients and >25 mm in 15 (14%) patients. The first branch originated 6.7 +/- 2.3 mm from the ostium. The left superior, right superior, right inferior, and left inferior PVs were found to enter the left atrium at the following angles: 32 +/- 13 degrees, 131 +/- 11 degrees, 206 +/- 16 degrees, and 329 +/- 14 degrees, respectively. Forty-nine patients (47%) had at least one funnel shaped PV. CONCLUSION: This largest PV imaging study to date demonstrates that MRA is a valuable tool that allows detection of marked intrapatient and interpatient anatomic variability of the PVs. These findings suggest that, at least in some patients, circumferential extra-ostial left atrial encirclement of the PVs may be preferable to ostial PV isolation. These findings also may have significant implications on the future development of coil- and balloon-based catheter ablation designs for AF ablation.     

Anatomy of the pulmonary veins in patients with atrial fibrillation and effects of segmental ostial ablation analyzed by computed tomography

INTRODUCTION: The anatomic arrangement of pulmonary veins (PVs) is variable. No prior studies have quantitatively analyzed the effects of segmental ostial ablation on the PVs. The aim of this study was to determine the effect of segmental ostial radiofrequency ablation on PV anatomy in patients with atrial fibrillation (AF). METHODS AND RESULTS: Three-dimensional models of the PVs were constructed from computed tomographic (CT) scans in 58 patients with AF undergoing segmental ostial ablation to isolate the PVs and in 10 control subjects without a history of AF. CT scans were repeated approximately 4 months later. PV and left atrial dimensions were measured with digital calipers. Four separate PV ostia were present in 47 subjects; 3 ostia were present in 2 subjects; and 5 ostia were present in 9 subjects. The superior PVs had a larger ostium than the inferior PVs. Patients with AF had a larger left atrial area between the PV ostia and larger ostial diameters than the controls. Segmental ostial ablation resulted in a 1.5 +/- 3.2 mm narrowing of the ostial diameter. A 28% to 61% focal stenosis was present 7.6 +/- 2.2 mm from the ostium in 3% of 128 isolated PVs. There were no instances of symptomatic PV stenosis during a mean follow-up of 245 +/- 105 days. CONCLUSION: CT of the PVs allows identification of anatomic variants prior to catheter ablation procedures. Segmental ostial ablation results in a significant but small reduction in ostial diameter. Focal stenosis occurs infrequently and is attributable to delivery of radiofrequency energy within the PV.     

Dreidimensionale Rekonstruktion der Pulmonalvenen und des linken Atriums

BACKGROUND: Selective pulmonary vein (PV) isolation to eliminate triggers is commonly used for curative catheter ablation of atrial fibrillation guided by two-dimensional (2-D) PV angiography, which is somewhat limited to depict the complex morphology of the PVs. 3-D mapping systems are limited to reconstruct the complete "true" anatomy by the reach of the mapping electrode related to catheter properties (maximum deflection and curve). New 3-D imaging systems (spiral computed tomography [CT] or magnetic resonance imaging [MRI]) provide detailed knowledge of the individual left atrial and PV morphology. Especially with the tampering, funnel-shaped PV ostia, identification of the PV ostium in selective PV isolation procedures aiming at the interruption of myocardial fibers is rather challenging using the 2-D imaging technique of contrast angiography. PATIENTS AND METHODS: In a total of 16 patients (13 male, three female, mean age 57 +/- 8 years), cardiac 3-D magnetic resonance angiography (MRA; 1.5 T, ACS Intera Philips, Germany) using an ECG-gated technique (1.3-1.7 mm slices) was performed. Using the postprocessing software Leonardo (Siemens, Germany), all adjacent anatomic structures such as the pulmonary artery were cut off to focus on the left atrium (LA) and PV anatomy. RESULTS: Left-sided PVs always entered in close proximity into the LA (common ostium in two patients). The right PVs entered more separately into the LA with a predominance of oval shapes. CONCLUSION: MRA is a noninvasive tool providing knowledge of the individual 3-D anatomy in a photorealistic fashion. Ultimately, image fusion with 3-D mappings systems would allow for true 3-D electrophysiologic mapping and could facilitate further understanding of the underlying substrate of so far "unsolved" complex arrhythmias such as atrial fibrillation in the future.     

Transesophageal echocardiographic follow-up of pulmonary veins in patients undergoing ostial radiofrequency catheter ablation for atrial fibrillation.

BACKGROUND: Ostial radiofrequency catheter ablation (RFCA) of pulmonary veins (PVs) is a promising invasive approach for the non-pharmacologic treatment of atrial fibrillation, but PV stenosis has been reported as a possible complication of this intervention. The aim of this study was to assess PV anatomy and stenosis (i.e. number and progression) by means of transesophageal echocardiography (TEE) during the follow-up of patients undergoing RFCA. METHODS: Twenty-three consecutive patients with refractory and highly symptomatic atrial fibrillation underwent ostial radiofrequency isolation of arrhythmogenic triggers/foci, localized into the PVs, by an electroanatomic approach (CARTO system) or circular mapping with a multipolar catheter (LASSO) placed under radioscopic guidance. All patients were investigated using TEE and magnetic resonance angiography before radiofrequency application to evaluate PV anatomy. TEE examination was repeated after 2 months of follow-up and, in the presence of a stenosis, 1 year later. RESULTS: TEE allowed to identify 100% of the left and right superior PVs, 96% of right inferior PVs, and 74% of the left inferior PVs. Anatomic variants were detected at TEE in 33% of patients against 37% at magnetic resonance angiography (95% of concordance). After ostial RFCA, TEE disclosed a significant reduction in the mean diameters of the left superior PV (14.1 +/- 3.2 vs 12.0 +/- 2.7 mm, p < 0.01), left inferior PV (11.2 +/- 2.3 vs 9.8 +/- 2.2 mm, p = 0.05) and right superior PV (14.2 +/- 2.6 vs 12.9 +/- 2.7 mm, p < 0.05), and an increase in the mean peak velocities of the left superior PV (69.8 +/- 14.8 vs 91 +/- 42.4 cm/s, p < 0.05) and left inferior PV (59.2 +/- 18.1 vs 79.3 +/- 40.5 cm/s, p < 0.05). From a total of 88 PVs treated, 7 (7.9%) showed a higher significant stenosis in patients treated using the LASSO than the CARTO system (31.3 vs 2.8% respectively, p < 0.01). After 1-year follow-up there was no progression of PV stenosis. CONCLUSIONS: TEE was successful to evaluate PV anatomy and stenosis of patients undergoing ostial RFCA for atrial fibrillation. This complication is not rare and seems to be strictly related to the method of ablation, in particular when circular mapping and disconnection of triggers/foci was carried out by only a circular multipolar catheter without an electroanatomic approach.     

Usefulness of a new radiofrequency thermal balloon catheter for pulmonary vein isolation: a new device for treatment of atrial fibrillation

INTRODUCTION: A rapidly firing or triggered ectopic focus located within a pulmonary vein (PV) or close to the PV ostium could induce atrial fibrillation (AF). The aim of this study was to evaluate the efficacy and safety of a radiofrequency thermal balloon catheter for isolation of the PV from the left atrium (LA). METHODS AND RESULTS: Twenty patients with drug-resistant paroxysmal AF were treated by isolating the superior PVs using an RF thermal balloon catheter. Using a transseptal approach, the balloon, which had an inflated diameter 5 to 10 mm larger than that of the PV ostium, was wedged at the LA-PV junction. It was heated by a very-high-frequency current (13.56 MHZ) applied to the coil electrode inside the balloon for 2 to 3 minutes, and the procedure was repeated up to four times. The balloon center temperature was maintained at 60 degrees to 75 degrees C by regulating generator output. Successful PV isolation was achieved in 19 of the 20 left superior PVs and in all 20 of the right superior PVs and was associated with a decrease in amplitude of the ostial potentials. Total procedure time was 1.8 +/- 0.5 hours, which included 22 +/- 7 minutes of fluoroscopy time. After a follow-up period of 8.1 +/- 0.8 months, 17 patients were free from AF, with 10 not taking any antiarrhythmic drugs and 7 taking the same antiarrhythmic agent as before ablation. Electron beam computed tomography revealed no complications, such as PV stenosis at ablation sites. CONCLUSION: The PV and its ostial region can be safely and quickly isolated from the LA by circumferential ablation around the PV ostia using a radiofrequency thermal balloon catheter for treatment of AF.     

Use of intracardiac echocardiography for prediction of chronic pulmonary vein stenosis after ablation of atrial fibrillation

INTRODUCTION: Measurements of pulmonary vein (PV) flow with intracardiac echocardiography (ICE) immediately before and after PV isolation may be a useful method for predicting which patients will develop chronic PV stenosis. METHODS AND RESULTS: We assessed preablation and postablation flows in each of the four PVs using a phase-array ICE catheter in 95 patients (mean age 52 +/- 13) undergoing atrial fibrillation ablation. The ostium of each of the PVs was defined using angiography, electrical mapping, and ICE imaging. Ostial electrical isolation of all PVs was achieved using a 4-mm cooled-tip radiofrequency ablation catheter. Change in PV flow, when present, was examined as both an absolute value and as a percentage of the baseline flow. All patients underwent spiral computed tomography (CT) scans of the PVs 3 months after the procedure for detection of stenosis. The average preablation diastolic flows for the left superior, left inferior, right superior, and right inferior veins were 0.56, 0.54, 0.47, and 0.45 m/sec, respectively. These values increased to 0.74, 0.67, 0.58, and 0.59 m/sec postablation (P < 0.001). Of 380 PVs ablated, the CT scans revealed 2 (1%) with severe (>70%) stenosis, 13 (3%) with moderate (51%-70%) stenosis, and 62 (16%) with mild (< or = 50%) stenosis. The r value between flow and stenosis was only 0.09 (P = NS). CONCLUSION: Acute changes in PV flow immediately after ostial PV isolation do not appear to be a strong predictor of chronic PV stenosis.     

Spatial torsion of the ipsilateral superior and inferior pulmonary veins

Purpose

We sought to evaluate the disregarded spatial torsion of the ipsilateral superior and inferior pulmonary veins (PVs).

Methods

Forty-eight consecutive atrial fibrillation patients, with four discrete PVs, were enrolled. The ostium plane of each PV, labeled by three landmarks on the CT image, was identified by three experienced observers respectively. Angle and distance between ostium planes were used to reach a consensus and to select the best ostium plane of each PV. A common ostium plane of the ipsilateral PV was computed using the two geometric centers of each side PVs and the axial center of the two geometric centers. The torsion angle was defined as the absolute difference of the two dihedral angles between the common ostium plane and the best ostium plane of the superior and inferior PVs.

Results

The torsion angle >15° was found in 16 left PVs (16/48) and in nine right PVs (9/48, P?=?0.104). Moreover, in two cases (2.1 %), the torsion angle exceeded 30° (one left PV and one right PV). The torsion angle of the left PVs was significantly greater than that of the right PVs (13.65?±?5.90° vs. 10.61?±?5.96°, P?=?0.014). Furthermore, in 29 paroxysmal AF patients, the spatial torsion of the left side PVs was 13.70?±?5.18°, which was significant greater than that of the right side PVs (10.69?±?5.52°, P?=?0.037).

Conclusions

There was a significant torsion between the ipsilateral PVs, which should be taken into account when physicians plan their ablation to avoid a single-plane circumferential ablation.     

肺静脉线-段-点联合消融治疗心房纤颤的临床观察

目的采用左房环状线性(线)消融、肺静脉口节段性(段)电隔离术加局灶性(点)消融法(简称线-段-点法)治疗心房纤颤(房颤),并研究该方法的有效性和安全性。方法采用8mm温控消融导管分别在左房环状线性消融左右侧上下肺静脉口周围,肺静脉口壶腹部节段性消融丛状电位,最后标测和点状消融提前的单相电位(在肺静脉内或心房内)。结果26例患者均行肺静脉开口外环状线性消融。电隔离肺静脉共89条。行点状消融共25例。26例中20例所有异常电位消失,6例肺静脉内仍有高耸的异常电位,但已达到传出阻滞。手术即刻成功率100%。随访4～8个月,24例(92%)未发作房颤;术后仍有房颤发作而服用抗心律失常药物后房颤发作明显减少者2例(8%)。未发生并发症。结论线-段-点联合消融法治疗房颤,方法简单,成功率高,并发症少。     

Three-dimensional analysis of pulmonary venous ostial and antral anatomy: implications for balloon catheter-based pulmonary vein isolation

BACKGROUND: Balloon ablation catheters using various energy sources are being developed to perform pulmonary vein (PV) isolation to treat atrial fibrillation. Prior evaluations of 2D CT/MR images are limited by the frequent elliptical shape of the PV ostia, the nonorthogonal orientation of the PVs to the left atrial (LA) chamber, and difficulty in appreciating through-slice curvature. To provide anatomical data relevant to balloon catheter ablation, 3D surface reconstructions of LA-PVs were generated and analyzed to define ostial architecture and size. METHODS AND RESULTS: Using MRI datasets obtained from 101 paroxysmal AF patients, the LA-PVs were segmented to generate 3D LA-PV surface reconstructions. Using both external and endoluminal projections, the PV ostial and antral regions were identified and evaluated. In the left PVs, a common left-sided ostium was identified in 94 patients, with an ostial circumference of 95 +/- 15 mm. Branching of the left PVs occurred 0-5 mm away from the common left ostium in 43 patients (43%), 5-15 mm away from the common os in 37 patients (37%), and >15 mm away from the common os in 14 patients (14%). In patients with either distinct left PV ostia, or common os <15 mm (87 patients), the individual LSPV/LIPV ostial circumferences were 67 +/- 12 mm and 58 +/- 9 mm, respectively. Mean left antral circumference was 114 +/- 17 mm. In the right PVs, the ostial circumferences of the RSPV/RIPV were 68 +/- 11 mm and 66 +/- 11 mm, respectively. Mean right antral circumference was 107 +/- 19 mm. Assuming ideal deformation of the LA chamber anatomy, the minimal diameters of a balloon ablation catheter required to isolate 95% of the RSPV, RIPV, LSPV, LIPV, LCPV, left antrum, and right antrum are 29 mm, 28 mm, 29 mm, 24 mm, 40 mm, 46 mm, and 47 mm, respectively. CONCLUSION: Analysis of 3D surface reconstructions of LA-PV anatomy reveals that balloon catheter-based ablation of the PVs is likely feasible in most patients, but balloon ablation of the common PV antra would be problematic.     

Phased-Array intracardiac echocardiography to guide radiofrequency ablation in the left atrium and at the pulmonary vein ostium

INTRODUCTION: We sought to evaluate the utility of a phased-array intracardiac echocardiography (ICE) device to identify left atrial (LA) and pulmonary vein (PV) anatomy; accurately guide radiofrequency ablation (RFA) to the right or left PV ostium and LA appendage (LAA); and evaluate PV blood flow before and after RFA using Doppler parameters. METHODS AND RESULTS: Twelve adult sheep were anesthetized and an Acuson 10-French, 7-MHz ICE transducer introduced via the internal jugular vein into the right atrium. The LA was imaged and PV anatomy and blood flow documented using two-dimensional and pulsed-wave Doppler. Mean LA dimensions were 4.6 +/- 0.4 x 3.5 +/- 0.5 cm; mean single right and left main PV ostium diameters were 1.5 +/- 0.2 and 1.3 +/- 0.3 cm; and mean right and left PV first-order branch diameters were 0.8 +/-0.2 and 0.6 +/- 0.1 cm. Mean PV maximum inflow velocity for the right PV were 0.30 +/- 0.05 m/sec and for the left PV were 0.35 +/- 0.04 m/sec. The PV ostia and LAA could be targeted accurately for RFA using ICE guidance. At pathologic evaluation, the mean distance of the lesion center to the right or left PV-LA junction was 3.0 +/- 2.0 mm. The mean distance of the lesion center to the posterior margin of the LAA was <4 mm in all cases. There was no significant increase in PV maximum inflow velocity or decrease in PV diameter following RFA at the PV ostium. Absence of PV obstruction was confirmed at pathology. CONCLUSION: Phased-array ICE allows detailed assessment of LA and PV anatomy when imaged from the right atrium; accurate guidance of RFA to the PV ostium and LAA; and immediate evaluation of PV patency after RFA.     

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.     

Intracardiac echocardiography-guided,anatomically based radiofrequency ablation of focal atrial fibrillation originating from pulmonary veins

OBJECTIVES: In patients with a pulmonary vein (PV) source for atrial fibrillation (AF), we sought the use of intracardiac echocardiography (ICE) to evaluate PV anatomy, guide radiofrequency (RF) ablation and monitor for acute stenosis during ablation. BACKGROUND: A focal source for AF may be found in the proximal component of the PVs and can be effectively treated by ablative techniques. However, the procedure may be challenging due to the complex anatomy of the left atrium and PVs, uncertain catheter positioning within the PVs and difficulties in mapping atrial extrasystoles, which may be rare or repeatedly induce AF and require cardioversion. METHODS: Sixty-four patients were referred for RF ablation of a focal source of AF, and 56 were identified as having AF triggers in > or =1 PV. Using ICE guidance, RF lesions were applied around the circumference of the vein near the os until there was electrical isolation. RESULTS: Lesions were placed in 82 veins (36 right superior PV, 33 left superior PV, 9 left inferior PV, 4 right inferior PV); 24 +/- 12 lesions per vein were necessary to create electrical isolation with a fluoroscopic time of 11 +/- 4 min and a mean of 22% reduction in luminal area. After a follow-up of 13 +/- 7 months, 66% of patients remained free of AF, and another 13% responded better to medications. CONCLUSIONS: We describe an anatomic approach to PV electrical isolation in which ICE is used to define the anatomy, guide RF ablation and monitor for acute PV changes.     

Detection of inadvertent catheter movement into a pulmonary vein during radiofrequency catheter ablation by real-time impedance monitoring

Introduction: During radiofrequency ablation to encircle or isolate the pulmonary veins (PVs), applications of radiofrequency energy within a PV may result in stenosis. The aim of this study was to determine whether monitoring of real-time impedance facilitates detection of inadvertent catheter movement into a PV.
Methods and Results: In 30 consecutive patients (mean age 53 ± 11 years) who underwent a left atrial ablation procedure, the three-dimensional geometry of the left atrium, the PVs, and their ostia were reconstructed using an electroanatomic mapping system. The PV ostia were identified based on venography, changes in electrogram morphology, and manual and fluoroscopic feedback as the catheter was withdrawn from the PV into the left atrium. Real-time impedance was measured at the ostium, inside the PV at approximately 1 and 3 cm from the ostium, in the left atrial appendage, and at the posterior left atrial wall. There was an impedance gradient from the distal PV (127 ± 30 Ω) to the proximal PV (108 ± 15 Ω) to the ostium (98 ± 11 Ω) in each PV (P < 0.01). There was no significant impedance difference between the ostial and left atrial sites. During applications of radiofrequency energy, movement of the ablation catheter into a PV was accurately detected in 80% of the cases (20) when there was an abrupt increase of ≥4 Ω in real-time impedance.
Conclusion: There is a significant impedance gradient from the distal PV to the left atrium. Continuous monitoring of the real-time impedance facilitates detection of inadvertent catheter movement into a PV during applications of radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 1-5, June 2004)     

Pulmonary vein antrum not always coaxial to the pulmonary vein: a dimensional pitfall to the circumferential isolation technique.

BACKGROUND: The dimensions and electrophysiological characteristics of the antral region of human pulmonary veins (PVs) were investigated. METHODS AND RESULTS: Fifty-five consecutive patients with symptomatic paroxysmal atrial fibrillation underwent PV isolation targeting the PV antrum potentials with a 31 mm multielectrode basket catheter (MBC). The most distal and proximal electrode pairs along the MBC spline where radiofrequency ablation was carried out were identified and the longitudinal distance between those ablation sites (Ld) was measured. When the Ld was > or =6 mm, the PV antrum was defined as noncoaxial. In 56% of the left superior PVs, 42% of the right superior PVs, 63% of the left inferior PVs and 56% of the right inferior PVs, a noncoaxial PV antrum was identified. In each PV, the radiofrequency ablation delivery duration and energy to complete the PV antrum isolation were significantly larger in the PVs with a noncoaxial PV antrum than in those with a coaxial PV antrum. CONCLUSION: The PV antrum is noncoaxial to the PV in >50% of the PVs, a feature that may increase the complexity of the circumferential isolation technique.     

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.     

Conduction recovery after pulmonary vein isolation for atrial fibrillation.

BACKGROUND: Although pulmonary vein (PV) isolation is useful for curing atrial fibrillation (AF), its recurrence rate is still high, so the aim of the present study was to investigate the cause of recurrence after PV isolation. METHODS AND RESULTS: Eighty-five patients with paroxysmal AF underwent PV isolation and AF recurred in 48 patients after the first session. Thirty of these 48 patients who underwent a second session were evaluated. In 49 (71%) of 69 PVs ablated in 25 patients (83%), recovery of conduction was observed between the left atrium and PV. In 45 (92%) of 49 PVs, conduction recurrences were seen from the same segment or part of a segment that was ablated in the first session. However, in the other 4 PVs (8%), conduction recurrences occurred in a different segment that had not been ablated before. In the second session, the mean number of segments ablated in the PV ostium was significantly less than in the first session (2.3+/-5.0 vs 1.4+/-6.0, p<0.01). After the second session, 16 patients (53%) did not show recurrence of AF. CONCLUSION: The major cause of recurrence of PV isolation was recovery of PV conduction from the same segment that had been ablated in the PV ostium. Therefore, an additional session may be necessary to increase the success rate.     

Role of Right Middle Pulmonary Vein in Patients with Paroxysmal Atrial Fibrillation

INTRODUCTION: Elimination of the ectopic foci from pulmonary veins (PVs) has proved to be a curative therapy for focal atrial fibrillation (AF). However, information about the importance of the right middle PV (RMPV) in initiation of AF and radiofrequency ablation of AF is limited. METHOD AND RESULTS: Forty-three patients (34 men and 9 women; age 65+/-12 years) with drug-refractory paroxysmal AF underwent electrophysiologic study and catheter ablation for treatment of AF. Three-dimensional magnetic resonance angiography (MRA) of the PVs and left atrium (LA) was performed to determine the anatomic patterns of RMPV. Diameter of PV ostium was measured at the junction of the LA and each PV. MRA findings showed the following: (1) 36 (84%) of 43 patients had a discrete RMPV; (2) there are three drainage patterns of RMPV, including joining the proximal part (<1 cm from the ostium) of the right superior PV (RSPV), joining the right inferior PV (RIPV), and a separate RMPV ostium in the LA wall; and (3) the ostial diameter of RMPV was significantly smaller than RSPV and RIPV (P < 0.01). Electrophysiologic studies demonstrated that five AF foci arose from RMPV. The coupling interval between the ectopic beat of AF and sinus beat was longer in RMPV than RSPV (262+/-45 msec vs 212+/-47 msec; P = 0.043). All AFs from RMPV were ablated successfully. PV stenosis or AF recurrence from RMPV was not found during follow-up of 10+/-4 months. CONCLUSION: RMPV was detected by MRA in >80% of paroxysmal AF patients. Ectopy from RMPV can initiate AF, and radiofrequency ablation of RMPV foci is feasible and safe.     

Morphologic Analysis of Left Atrial Anatomy by Magnetic Resonance Angiography in Patients With Atrial Fibrillation: A Large Single Center Experience

LA and PV Anatomy in Patients With AF. Introduction: Although transcatheter atrial fibrillation (AF) ablation requires accurate anatomic knowledge, pulmonary vein (PV) anatomy has not been fully investigated. Aim of this study is to describe left atrium (LA) and PV anatomy by magnetic resonance angiography (MRA) in a large cohort of patients with AF. Methods: MRA was performed in 473 patients preceding transcatheter AF ablation (paroxysmal 60.9%; persistent 39.1%). The Venice Chart classification was used to classify PV branching patterns. Results: About 40% of the patients presented typical PV branching pattern (2 left and 2 right PVs). A representative number of patients presented a common left trunk (19.9% and 11.0% short and long, respectively). A right middle PV was described in 12.5% and 2 right middle PVs in 1.5% patients. The remaining patients presented other complex, previously unclassified patterns: 6.3% presented an accessory PV originating from LA areas not describable as right or “upper” and 8.7% a common left trunk plus right middle PV. Diameters and circumference of each PV, LA, and LA appendage volumes resulted larger in patients presenting persistent compared to paroxysmal AF (P < 0.001). Conclusion: This study highlights that “typical” PV branching pattern is not a common finding. That 25.6% of the patients present at least 1 accessory PV needs to be kept in careful consideration when planning and performing transcatheter AF ablation. In addition, not only LA volume, but also each PV ostia and LA appendage are significantly enlarged in patients with persistent compared to paroxysmal AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1‐7, January 2011)     

多排螺旋CT检测肺静脉变异及肺静脉孔指数在心房颤动射频消融术前的应用

目的评价心房颤动（房颤）射频消融术前肺静脉变异类型及肺静脉孔指数。方法回顾性分析2005年6月至2006年5月房颤患者射频消融术前16排螺旋CT肺静脉造影64例,在最大密度投影重建图像上测量左上、左下、右上、右下、共干及独立肺静脉孔处肺静脉的前后径及上下径,计算肺静脉孔指数,比较左上、左下、右上、右下肺静脉孔指数差异有无统计学意义。所有统计工作由SPSS软件完成。结果在64例房颤患者中,肺静脉正常无变异11例,占17．19％;肺静脉提前分支45例,占70．31％,共69支肺静脉;左侧共干5例,占7．81％,其中1例两侧共干;右侧独立肺静脉5例,占7．81％;左侧中肺静脉1例,占1．56％。同侧、两侧上肺静脉的肺静脉孔指数差异无统计学意义,P〉0．05。左上与右下、左下与右上及两下肺静脉的肺静脉孔指数差异有统计学意义,P〈0．05。右下肺静脉孔最圆,平均指数最大,为0．88;左下肺静脉孔最接近椭圆型,平均指数最小,为0．72。结论多排螺旋CT肺静脉造影能为房颤射频消融术提供肺静脉解剖信息,如肺静脉变异及肺静脉孔指数,应列为术前常规检查。     

Arrhythmogenic Potential of Pulmonary Venous Tissue: Triggers for Atrial Fibrillation Identified within the Remnant of a Vein

Background: Pulmonary veins (PVs) have frequently been identified as triggers for atrial fibrillation (AF), and higher arrhythmogenic potential of superior PVs has been attributed to their larger size, which can more rigorously support abnormalities of impulse formation and/or conduction.
Case Report: Contrary to this belief, we report our observations in a 63-year-old patient with history of lung cancer, S/P left upper lobectomy, undergoing ablation for paroxysmal AF. Circular mapping (Lasso) and ablation (ABL; 8-mm) catheters were deployed in left atrium (LA). Intracardiac ultrasound revealed separate right superior (RS) and inferior (RI) PVs and a single left PV. Segmented LA anatomy from the CT angiogram images corroborated this, although on the latter there appeared to be a "stump" at superior aspect of the left PV. This stump likely was the remnant of the left superior (LS) PV. Thus, the patent left vein was likely the dilated left inferior (LI) PV. With the Lasso and ABL deployed at the LIPV ostium and LSPV remnant, respectively, AF was reproducibly seen to initiate with earliest activity in the latter. Single radio-frequency ablation (RFA) lesion within the LSPV remnant abolished AF triggers. Additional RFA was done to isolate LI, RS, and RI PVs. Over a follow-up period of 24 months, this patient has remained free from AF off any drugs.
Conclusions: Our observations suggest that even very proximal remnants of PVs can serve as triggers for AF. Recognition of this phenomenon was facilitated by the use of advanced imaging technique and the deployment of multiple catheters.