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.     

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.     

Endocardial impedance mapping during circumferential pulmonary vein ablation of atrial fibrillation differentiates between atrial and venous tissue

BACKGROUND: Circumferential pulmonary vein ablation (CPVA) is an effective treatment for atrial fibrillation (AF). Accurate left atrial (LA) mapping is essential for creating lesions at the LA-pulmonary vein (PV) junction, avoiding PV stenosis. OBJECTIVES: The purpose of this study was to establish whether endocardial impedance varies within the LA and PVs and whether it is a useful tool for mapping and ablation. METHODS: Pilot Phase: Three-dimensional LA maps were created using CARTO. Impedance (Z) was measured using a radiofrequency generator at multiple points in the LA, PV ostia (PVO), and deep PVs in 79 patients undergoing their first AF ablation (group 1) and 29 patients undergoing repeat CPVA (group 2). Prospective Phase: In an additional 20 patients, using pilot phase data, one operator defined catheter tip location as either LA or PVO based on CARTO and fluoroscopy. A second operator blinded to CARTO simultaneously did the same based on impedance at 15 +/- 4 points per patient. RESULTS: Group 1: Z(LA) was 99.4 +/- 9.0 omega. Z(PVO) was higher (109.2 +/- 8.5 omega), rising further as the catheter advanced into deep PV (137 omega +/- 18). Z(PVO) differed from Z(LA) by 9 +/- 4 omega. Group 2 had a lower Z(LA) and Z(PVO) compared with group 1 (P <.05). Impedance monitoring differentiated between LA and PVO, with 91% specificity and sensitivity, 96% positive predictive value, and 81% negative predictive value. At 3-month follow-up, no patients had evidence of PV stenosis on magnetic resonance imaging. CONCLUSION: Impedance mapping reliably identifies the LA-PV transitional zone, facilitating AF ablation, and its use is associated with a low incidence of PV stenosis.     

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.     

环静脉导管消融术的消融达终点部位分析及相应的策略

目的分析以电隔离为终点的环肺静脉导管消融过程中,消融达终点部位的分布规律,并探讨相应的标测策略和消融技巧。方法入选症状明显、药物治疗无效的心房颤动患者452例。在三维电解剖标测系统(CAR-TO)指导下行导管射频消融,均采用环肺静脉电隔离术为基本术式,使用单个环状电极标测肺静脉电位,消融终点为肺静脉电隔离。在环肺静脉消融过程中,用CARTO标记出消融达终点部位,即肺静脉心房肌束连接部位,通常表现为消融后肺静脉电位明显延迟、频率明显减慢或消失。结果在452例的消融过程中共记录到消融达终点部位1520处,包括环左侧肺静脉813处,最常见于左前上(201处,24.7%)、左前中(180处,22.1%)和左前下(132处,16.2%);环右侧肺静脉707处,最常见于右后中(207处,29.3%)和右后上(162处,22.9%)。所有单圈未隔离而在环肺静脉消融线上补点消融的病例中,961个消融达终点部位(82.99%)与环状电极指示区域一致,通过在消融线上大头仔细标测进一步确定消融达终点部位,并根据不同的部位分别采用增加消融时间、冷盐水灌注的流速以及改变导管贴靠方式等方法可有效地达到肺静脉电隔离的消融终点。结论环静脉导管消融术达到电隔离终点的常见消融达终点部位分布有一定规律,最多见于左侧消融线前壁和右侧后壁,环状电极可有效提示消融达终点部位的大体位置,采用改变导管贴靠方式以及增加消融时间、冷盐水流速等方法可以有效阻断消融达终点部位,达到电隔离终点。     

Prevalence of pulmonary vein disconnection after anatomical ablation for atrial fibrillation: consequences of wide atrial encircling of the pulmonary veins.

AIMS: Anatomical and wide atrial encircling of the pulmonary veins (PVs) has been proposed as a cure of atrial fibrillation (AF). We evaluated the acute achievement of electrical PV isolation using this approach. In addition, the consequences of wide encircling of the PVs with isolation were assessed. METHODS AND RESULTS: Twenty patients with paroxysmal AF were studied. Anatomically guided ablation was performed utilizing the CARTO system to deliver coalescent lesions circumferentially around each PV to produce a voltage reduction to <0.1 mV, with the operator blinded to recordings of circumferential PV mapping. After achieving the anatomical endpoint, the incidence of residual conduction and the amplitude and conduction delay of residual PV potentials were determined. Electrical isolation of the PV was then performed and the residual far-field potentials evaluated. Individual PV ablation was performed in all PVs. Anatomically guided PV ablation was performed for 47.3+/-11 min, after which 44 (55%) PVs were electrically isolated. In the remaining 45%, despite abolition of the local potential at the ablation site, PV potentials [amplitude 0.2 mV (range 0.09-0.75) and delay of 50.3+/-12.6 ms] were identified by circumferential mapping. After electrical isolation (12.2+/-11.7 min ablation), 55 (69%) PVs demonstrated far-field potentials; with a greater incidence (P=0.015) and amplitude (P=0.021) on the left compared with the right PVs. At 13.2+/-8.3 months follow-up, 13 patients (65%) remained arrhythmia-free without anti-arrhythmics. In four patients (20%), spontaneous sustained left atrial macrore-entry required re-mapping and ablation. Macrore-entry was observed to utilize regions around or bordering the previous ablation as its substrate. CONCLUSION: Anatomically guided circumferential PV ablation results in apparently coalescent but electrically incomplete lesions with residual conduction in 45% of PVs. Wide encircling of the PVs was associated with left atrial macrore-entry in 20% of patients.     

Effects of circumferential ostial radiofrequency lesions on pulmonary vein activation recorded with a multipolar basket catheter

AIMS: Two different ablation procedures are performed to cure patients of atrial fibrillation (AF): (1) the electrophysiological pulmonary vein (PV) isolation, and (2) the anatomical circumferential ablation of all four PV ostia. The aim of this study was to determine the effects of circumferential radiofrequency lesions around the ostia on PV activation. METHODS AND RESULTS: In 34 patients with drug refractory paroxysmal (N = 22) or persistent (N = 12) AF a 31-mm basket catheter (BC) was introduced transseptally in the PVs. After creating a circumferential ablation line around the PV ostia using a nonfluoroscopic 3D-navigation system, electrical isolation was achieved in 46% of the PVs, and prolongation of conduction time (+39 +/- 34 ms) was observed in 30%. PVs with persistent conduction (54%) were isolated by ablating the remaining conduction pathways using the BC. At 12 months follow-up, 62% of the patients were in stable sinus rhythm without antiarrhythmic drug therapy. Six patients had developed left atrial flutter. CONCLUSIONS: Anatomically guided, circumferential lesions around the PV ostia resulted in isolation in only 46% of the veins. At 12 months, 62% of the patients were free of AF without antiarrrhythmic drug treatment, however, 6 patients (18%) developed left atrial flutter.     

Safety and efficacy of circumferential pulmonary vein catheter ablation of atrial fibrillation.

OBJECTIVES: The purpose of this study was to report the safety, efficacy, and predictors of recurrence of circumferential pulmonary vein (PV) catheter ablation in patients with atrial fibrillation (AF). BACKGROUND: Circumferential PV ablation has been described as an alternate ablation strategy for AF. METHODS: Seventy consecutive patients (age 56 +/- 10 years) with symptomatic drug refractory paroxysmal (n = 21), persistent (n = 22), and permanent (n = 27) AF underwent catheter ablation. The catheter ablation procedure was performed by creating circular lesions encircling right- and left-side PV ostia guided by an electroanatomic (CARTO) mapping system. Linear ablation lesions also were created in the cavotricuspid isthmus, the mitral isthmus, and in the posterior left atrium. In 42 patients (60%), additions linear lesions were created between superior and inferior PVs in a "figure-of-eight" fashion. RESULTS: At 6 +/- 2.5 months of follow-up, 53 patients (76%) were AF free, including 39 patients (56%) not taking and 14 patients (20%) taking antiarrhythmic drugs. Among various variables, only early recurrence of AF was a predictor of long-term recurrence. Significant complications included one pericardial tamponade, one stroke, and two PV occlusions. Both patients with PV occlusion received radiofrequency delivery in a figure-of-eight fashion. CONCLUSIONS: Circumferential PV catheter ablation of AF is associated with moderate efficacy and risk of complications. The absence of a difference in efficacy combined with the risk of PV stenosis associated with figure-of-eight lesion lead us to conclude that the figure-of-eight lesion should not be a routine component of circumferential PV AF ablation procedures.     

Incidence and location of focal atrial fibrillation triggers in patients undergoing repeat pulmonary vein isolation: implications for ablation strategies

INTRODUCTION: The etiology of atrial fibrillation (AF) recurrences after pulmonary vein (PV) isolation is not well described. The aim of this study was to examine the reason for recurrent AF in patients undergoing a repeat attempt at AF trigger ablation. METHODS AND RESULTS: Patients with recurrent AF more than 1 month after ablation returned for repeat mapping and ablation. A circular mapping catheter was advanced to each previously targeted PV ostium to determine if the PV was still electrically isolated. Ectopy then was provoked with isoproterenol (up to 20 microg/min), burst pacing, and pacing into AF followed by cardioversion. The location of ectopy triggering atrial premature depolarizations (APDs) or AF was noted. Of 226 patients who underwent ablation of AF triggers, 34 (8 women and 26 men; age 56 +/- 10 years) with recurrent AF returned for a repeat procedure 207 +/- 183 days after the first procedure. There were 84 previously completely isolated PVs in these 34 patients. Thirty-three (39%) of 84 previously isolated PVs were still completely isolated at the time of the second procedure. Fifty-one PVs (61%) had evidence of recovered PV potentials. Fifty triggers of APDs and AF (n = 30) or APDs only (n = 20) were identified in these 34 patients. The majority of triggers [27/50 (54%)] originated from previously targeted PVs. Sixteen triggers [16/50 (32%)] originated from previously nontargeted PVs. CONCLUSION: The majority of AF recurrences originate from previously isolated PVs. One third of recurrent triggers originated from PVs that were not targeted during the initial ablation session. Although empiric isolation of all PVs may reduce recurrences, strategies to ensure ostial PV isolation and to prevent recurrent PV conduction after ablation should have the greatest impact on reducing AF recurrence.     

Determination of the spatial orientation and shape of pulmonary vein ostia by contrast-enhanced magnetic resonance angiography.

AIMS: For catheter ablation of atrial fibrillation (AF), proper catheter positioning is crucial and depends on knowledge of pulmonary vein (PV) anatomy. The aim of this study was to assess PV spatial orientation and ostial shape by contrast-enhanced magnetic resonance angiography (CE-MRA). METHODS AND RESULTS: In 30 consecutive AF patients, CE-MRA was performed prior to ostial ablation. Using a centre-line technique, the PV ostium was defined perpendicular to this centre-line. Minimal and maximal ostial diameters, ostial perimeter, and angles in the anatomical frontal and transverse planes were measured. Twenty-one patients had four separate PVs. In four patients, there was a distinct right-middle PV and in five a common left common PV was found. Left-sided PV ostia were smaller and more elliptical than right-sided PVs. In the transverse plane, the ostia of both superior PVs were directed anteriorly (LS -15 +/- 13 degrees , RS -13 +/- 11 degrees ) and both inferior PV ostia were directed posteriorly (LI 23 +/- 15 degrees , RI 39 +/- 15 degrees ). In the frontal plane, both superior PV ostia pointed upwards (LS -27 +/- 14 degrees , RS -33 +/- 12 degrees ) while the inferior ostia were directed horizontally (LI 2 +/- 11 degrees , RI 3 +/- 13 degrees ). CONCLUSION: PV ostial shape and spatial orientation are variable and can be visualized adequately by CE-MRA.     

Balloon catheter ablation to treat paroxysmal atrial fibrillation: What is the level of pulmonary venous isolation?

BACKGROUND: Unlike the initial balloon ablation catheters that were designed to deliver ablation lesions within the pulmonary veins (PVs), the current balloon prototypes are fashioned to deliver lesions at the PV ostia. OBJECTIVE: Using electroanatomical mapping, this study evaluates the actual location of ablation lesions generated by cryo-based, laser-based, or ultrasound-based balloon catheters. METHODS: In a total of 14 patients with paroxysmal atrial fibrillation, PV isolation was performed using either a cryoballoon catheter (8 patients), laser catheter (4 patients) or ultrasound balloon catheter (2 patients). Patients underwent preprocedural computed tomographic/magnetic resonance imaging. An intracardiac ultrasound catheter was used to aid in positioning the balloon catheter at the PV ostium/antrum. In all patients, sinus rhythm bipolar voltage amplitude maps (using either CARTO with computed tomographic/magnetic resonance image integration or NavX mapping) were generated at baseline and after electrical PV isolation as confirmed by use of a circular mapping catheter. RESULTS: Electrical isolation was achieved in 100% of the PVs. Electroanatomical mapping revealed that after ablation with any of the 3 balloon catheters, the extent of isolation included the tubular portions of each PV to the level of the PV ostia. However, the PV antral portions were left largely unablated with all 3 balloon technologies. CONCLUSION: Using the current generation of balloon ablation catheters, electrical isolation occurs at the level of the PV ostia, but the antral regions are largely unablated.     

三维标测系统指导下环肺静脉消融治疗心房颤动

目的 探讨三维标测系统指导下环肺静脉消融治疗心房颤动的安全性和有效性.方法 阵发性心房颤动92例和持续性或永久性心房颤动36例,接受环肺静脉消融术.采用Carto电解剖标测系统,进行环肺静脉左心房线性消融,消融终点为肺静脉电隔离.手术结束时对心律仍为心房颤动者行同步直流电心脏复律.结果 完成"解剖学"环形消融线256条,其中58.6%达到电隔离肺静脉的终点,经寻找缝隙补充消融后最终248条(96.9%)消融线达到终点.手术时间(231±45)min、X线曝光时间(42±13)min和放电时间(66±17)min.术后随访平均10个月,无复发101例(78.9%).接受了再次手术15例,心内电生理检查证实14例有左心房-肺静脉传导,射频消融成功并随访30～270 d,两次射频消融术后总成功率为87.5%,其中阵发性心房颤动成功率为93.0%,持续性或永久性心房颤动为76.7%.并发症发生率为6.2%,包括心包填塞2例、小脑梗死2例、股静脉穿刺部位血肿1例和左侧大量血胸1例,经治疗后均痊愈.结论 以肺静脉电隔离为目标的环肺静脉消融术治疗心房颤动有效和安全.     

Atrial fibrillation and effective refractory period of the pulmonary vein ostia.

BACKGROUND: The pathogenesis of atrial fibrillation (AF) is not completely understood. The role of pulmonary veins (PV) in AF initiation is documented, and the recent demonstration of persistent fibrillatory activity in an isolated PV suggests that the PV play a role in the maintenance of AF. OBJECTIVE: Since AF is facilitated by multiple reentry circuits in atrial tissue with short effective refractory periods (ERP) and prolonged conduction times, we investigated whether PV have shorter ERP compared with the left atrium (LA). POPULATION AND METHODS: The study population consisted of five male patients, between 45 and 78 years of age, with normal sized LA; three had coronary artery bypass surgery (and no previous history of atrial arrhythmias) and two had paroxysmal lone AF refractory to antiarrhythmic drugs and were referred for percutaneous ablation with radiofrequency energy. In the surgical patients, epicardial bipolar pacing wires were inserted in the PV ostia and LA roof at the end of the procedure. Post-operatively, the pacing wires were used to determine atrial thresholds and ERP in the PV ostia and LA roof. In the AF patients, atrial thresholds and ERP at these locations were obtained with the mapping/ablation catheter before and after PV isolation. ERP were determined with a basic pacing cycle length of 500 ms and a single extrastimulus with an initial coupling interval of 350 ms, gradually decreased (10 ms at a time) until atrial capture failure or AF induction. RESULTS: ERP in the LA roof were longer than 210 ms. The shortest ERP was always obtained in a PV ostium, with the shortest in the left PV ostia. The ERP values of the right inferior PV most resembled those of the LA roof. In patients referred for ablation, AF was induced when PV ostia with ERP shorter than 200 ms were stimulated. CONCLUSION: In the present study, the ERP of PV ostia were shorter than LA ERP, possibly explaining not only the presence of ectopic foci in the PV ostia, but also sustained fibrillatory activity in isolated PV, despite conversion of the atria to sinus rhythm. This fact may also explain the higher success rate and the preference for PV isolation in AF ablation.     

Mechanisms of recurrent atrial fibrillation after pulmonary vein isolation by segmental ostial ablation

OBJECTIVES: The aim of this study was to determine the mechanisms responsible for recurrent atrial fibrillation (AF) after pulmonary vein isolation (PV) by segmental ostial ablation. BACKGROUND: Recovery of conduction into a previously isolated PV is a common observation when there is recurrent AF soon after segmental ostial ablation. However, the mechanisms of recurrent AF have been unclear. METHODS: A repeat ablation procedure was performed in 50 patients who had recurrent paroxysmal AF at a mean of 7 +/- 6 months after segmental ostial ablation to isolate the PVs. During the repeat procedure, a ring catheter was inserted into each PV during sinus rhythm and AF to determine whether the veins were still isolated and, if not, whether there were PV tachycardias with a cycle length shorter than in the adjacent left atrium during AF. RESULTS: There was recovery of conduction over a previously ablated muscle fascicle in >/=1 PV in 49 patients (98%). There were 10 +/- 2 episodes of PV tachycardia per minute in 36 (72%) of the 50 patients during AF. Repeat ablation was performed by segmental ostial ablation (23 patients) or by left atrial catheter ablation to encircle the left- and right-sided PVs 1 to 2 cm from the ostia, with additional ablation lines in the posterior left atrium and mitral isthmus (27 patients). At 6-month follow-up, among 23 patients who underwent repeat ablation by segmental ostial ablation, AF recurred in 4 (21%) of the 19 patients who had PV tachycardias and in 3 (75%) of the 4 patients who did not (P = .03). Among the 27 patients who underwent left atrial ablation, AF recurred in 2 (12%) of the 17 patients who had PV tachycardias and in 1 (10%) of the 10 patients who did not (P = 0.7). CONCLUSIONS: Recovery of conduction in previously ablated muscle fascicles is a common finding in patients with recurrent AF after segmental ostial ablation. The efficacy of repeat segmental ostial ablation depends on the presence of PV tachycardias, whereas left atrial ablation is effective regardless of whether PV tachycardias are present or not during AF.     

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.     

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.     

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)     

Intracardiac Doppler echocardiographic quantification of pulmonary vein flow velocity: an effective technique for monitoring pulmonary vein ostia narrowing during focal atrial fibrillation ablation

INTRODUCTION: Ablation at the pulmonary vein (PV) ostium to isolate triggers for atrial fibrillation (AF) may induce PV narrowing. The AcuNav ultrasound catheter can image PV flow and quantify peak velocity and may be useful in assessing the degree of narrowing of PV ostia. METHODS AND RESULTS: In 93 patients with AF undergoing PV ostial ablation (up to 40 W, 52 degrees C, 90 sec), the ultrasound catheter was placed in the right atrium and PV peak flow velocities were measured during systole and diastole before and after ablation. Ostial PV electrical isolation was achieved in 216 of the 219 targeted PVs. The ultrasound catheter provided flow imaging of all PVs. The ostial peak flow velocities measured 56 +/- 12 cm/sec before ablation and increased to 101 +/- 22 cm/sec after ablation (P < 0.001). Peak velocity >100 cm/sec was detected in 103 (47%) of 219 and > or = 158 cm/sec (estimated pressure gradient 10 mmHg) with turbulent flow features, in 7 (3.2%) of 219 PVs. The highest velocity detected in one PV was 211 cm/sec (17.7 mmHg). Follow-up ultrasound catheter measurements were obtained in 13 patients (30 previously ablated PVs) during repeat ablations. The ostial peak velocity had decreased by 22 +/- 14 cm/sec and in 25 (83%) of 30 PVs was within the baseline range (<100 cm/sec) at a mean follow-up of 4.9 +/- 2.2 months. Follow-up magnetic resonance imaging (MRI) or contrast-enhanced CT was obtained at 7.0 +/- 3.8 months in seven patients with PV velocity > 158 cm/sec after initial ablation. No significant stenosis (<30%) was identified, and no patient suffered clinical symptoms (follow-up 6-18 months) related to the described acute changes in PV flow after an initial ablation procedure. Of 13 patients with repeat ablation, two had PV velocities >100 cm/sec before repeat ablation, and three PVs in two patients had flow velocity >158 cm/sec after repeat ablation. One of these patients developed symptoms of exertional dyspnea; MRI at 4 months showed 50% to 60% ostial narrowing. CONCLUSION: Ostial ablation for PV isolation may induce a mild-to-moderate increase in PV flow velocity, which can be identified using an ultrasound catheter with Doppler color flow imaging. Increases in PV flow velocity (<158 cm/sec) after a primary ablation procedure appear to be well tolerated, and a return toward baseline flow characteristics should be anticipated by 3 months. A more cautious approach may be required for patients undergoing repeat PV isolation.     

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.     

Electrophysiologically guided pulmonary vein isolation during sustained atrial fibrillation

INTRODUCTION: Sustained atrial fibrillation (AF) is frequently encountered during pulmonary vein (PV) isolation. The aim of this study was to evaluate the feasibility and safety of PV isolation during sustained AF. METHODS AND RESULTS: Thirty-seven patients (30 men, age 54 +/- 10 years) underwent Lasso-guided isolation of 87 PVs during sustained AF. Baseline PV electrogram patterns were classified into one of two types: organized, with consistent PV activation sequence; or disorganized, with constant variation of PV activation sequence. In disorganized activity, radiofrequency ablation was performed circumferentially around the Lasso while the earliest PV potential was targeted during organized activity. Complete left atrial (LA) to PV block during AF was identified by abolition or dissociation of all sharp potentials recorded within the vein. PV isolation then was verified during sinus rhythm. Baseline activation patterns of PV potential were organized in 32 PVs (37%) [more frequently in inferior veins than superior veins (53% vs 26%, P = 0.01)] and disorganized in 55 PVs (63%). In 59 of 87 PVs, isolation was begun and completed during AF. Radiofrequency ablation organized PV activation sequence in 75% prior to isolation. LA-PV block was confirmed during sinus rhythm in 54 (92%) of 59 PVs. In 28 of 87 PVs, sinus rhythm was restored before complete LA-PV block. Complete isolation was achieved in all 87 PVs without complications. CONCLUSION: PV isolation can be effectively and safely performed during sustained AF, preceded in most cases by organization of PV electrogram activity. This strategy may be the preferred alternative to multiple intraprocedural cardioversions.