This article appears in the following Europace issue: Spotlight Issue: Cardiac Imaging in EP and CRT [View the issue table of contents]
IMAGING IN CATHETER ABLATION FOR AF
Imaging of pulmonary veins during catheter ablation for atrial fibrillation: the role of multi-slice computed tomography
Division of Cardiology, Department of Medicine, Johns Hopkins University, Carnegie 592, 600 N Wolfe Street, Baltimore, MD 21287, USA
* Corresponding author. Tel: +1 410 955 2412; fax; +1 410 955 0223.E-mail address: chenriks{at}jhmi.edu
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Detailed anatomic imaging of the left atrium and related structures prior to ablation of atrial fibrillation (AF) is important for planning the procedure, enabling the use of advanced mapping techniques, and avoiding complications. Multidetector computed tomography (MDCT) allows visualization of the entire left atrium and each pulmonary vein (PV). This method provides precise delineation of anatomical features and dimensions by several types of reconstructed images. Additionally, the MDCT images are used with the electroanatomical mapping system to help guide the safe and effective catheter ablation of AF. MDCT also has been used for the assessment of serial changes in ablated PVs to detect and evaluate PV stenosis. The use of MDCT greatly aids the planning and complication-free execution of AF ablation.
Key Words: Multidetector computed tomography, Atrial fibrillation, Pulmonary vein, Ablation, Anatomy
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The most common sustained supraventricular arrhythmia in the adult is atrial fibrillation (AF). The overall prevalence of AF is reported as 0.4%.1
,2 The prevalence of AF increases with age: it is estimated that 
5–6% of those aged 65 years, 8–12% of those aged 80 years, and 16–20% of those aged >85 years have AF.3–5 In most patients, AF is treated for two reasons—to decrease the risk of stroke, and to relieve symptoms. Left atrial appendage (LAA) thrombi can be documented 10% of AF patients in the absence of anticoagulation.6–8 These thrombi associated with AF lead to a risk of stroke several times higher than the general population.9,10 In a minority of patients with AF, the loss of atrial stroke volume and atrial systole, combined with high heart rate, can lead to left ventricular dysfunction and cardiac failure.3
In 1998, Haissaguerre et al. first reported that multiple ectopic foci originating from pulmonary veins (PV) played important roles in the initiation and maintenance of AF.11 The left atrial myocardium extends a variable length into the PVs. These extended myocardial sleeves appear to be the foci for the ectopic electrical discharge.11–14 Therefore, the PVs are important targets for the curative ablation of AF. Additionally, other regions of the left and right atria can harbor areas of complex fractionated electrograms, which appear to be crucial to the maintenance of AF, and can be found in superior vena cava, both atria, the crista terminalis, ostium of the coronary sinus, and the intraatrial septum.7,11,15,16 Electrical isolation of the PVs is the cornerstone of curative procedures for AF.11,16,17 This can be accomplished by surgical methods,18 or via catheter-based radio frequency ablation (RFCA).19 AF ablation can also be performed using a variety of non-radiofrequency-based energy delivery systems. However, for any catheter-based procedure, detailed anatomic imaging of the left atrium and associated structures is very important to plan the procedure, to allow the use of advanced electroanatomical mapping (EAM) systems during the procedure, and to avoid complications.
Why computed tomography imaging is useful as a guide for AF ablation
For current RFCA for AF, the ablation catheter is placed into the left atrium via transseptal puncture under fluoroscopic and/or intracardiac echocardiographic guidance.20–23 Each PV is cannulated with the ablation catheter and a lasso mapping catheter to look for electrical activity in the vein and to guide ablation. Typical left atrial anatomy with four distinct PVs is found in 70% of cases, but the remaining 30% show anatomical variants of the PVs.12 Thus, it is helpful to determine the precise anatomy as a guide for RFCA preoperatively. While there is considerable variation in the approach to RFCA for AF, at most centers RFCA for AF focuses on PV isolation at the ostium.24,25 At our center, wide-area circumferential ablation is undertaken first, with continuous lines of RF lesions created around the left and right PVs. Then, each vein is individually mapped with the lasso catheter, and if not yet electrically isolated, ‘touch up’ ablation is performed until electrical signals in the vein are dissociated from the atrium, or extinguished altogether. Preoperative evaluation of the left atrium and the PVs provides important information for the procedure, and reduces fluoroscopic and procedural time,16,26–30 and unexpected complications.31–33 In the absence of preprocedural imaging, it is difficult to assess completely the anatomy of PVs and left atrium, and can result in greater total amounts of contrast media and radiation time, in addition to less effective use of the EAM system (CARTOMERGE, Biosense, Webster, Diamond Bar, CA).26–30 Additionally, multidetector computed tomography (MDCT) scan can help guide the transseptal puncture, especially in cases of abnormal positioning or angulation of the interatrial septum.
Preprocedural imaging for AF RFCA should include: (i) the precise anatomy of left atrium and PVs, (ii) the precise measurement of each ostial diameter and the distance to the first branch, (iii) presence of accessory or supernumerary PVs, (iv) the left atrial dimension and the presence of LAA thrombus, and (v) major anomalies like common PV ostia, persistent left superior vena cava, anomalous pulmonary venous return, vein of Marshall, or the hypoplasty or occlusion of PV. If anatomic abnormalities of the left atrium or PVs are present, extra care should be taken to examine for accessory veins which arise from an independent atriovenous junction, and which may be small and at higher risk of occlusion at time of RFCA.
The presence of thrombus in the LAA or left atrium proper has been associated with a higher risk of thromboembolism and cerebrovascular accident. Although transesophageal echocardiography (TEE) is the standard technique to exclude LAA thrombus, several recent studies have reported the usefulness and limitations of MDCT angiography in the assessment of LAA thrombus.34,35 One study using electron beam computed tomography showed high sensitivity and specificity for the detection of left atrial thrombus in AF patients.36 The contrast-enhanced MDCT may demonstrate the filling defect in the left atrium or LAA. But some factors may affect its accuracy including the image quality, difficulties in distinguishing clot from pectinate muscle, and delayed contrast filling of the LAA during AF. Additional improvements in temporal resolution and in acquisition technique may provide the useful information of left atrium and LAA thrombus by MDCT angiography.34,35
Several investigational technologies involve placement of a balloon catheter at the ostium of the PVs to allow delivery of energy around the PV ostia. MDCT angiography can be particularly helpful in these instances to examine for anatomical variation such as a common PV trunk that will exclude the use of these devices.37,38
Comparison of computed tomography imaging of the pulmonary veins with other imaging modalities
There are a variety of available imaging modalities available for preprocedural assessment of AF ablation, including fluoroscopy, TEE,39 intracardiac echocardiography (ICE),20 magnetic resonance imaging (MRI),40 as well as MDCT angiography.13 Fluoroscopy is an integral part of all catheter ablation procedures, and the PVs can be visualized with the selective injection of contrast, however, only a two-dimensional image is obtained. TEE is typically used to examine for LAA thrombus and PV flow velocities pre-RFCA and can be used as a monitor during the procedure, however, this is often not practical to have the TEE probe in the patient for the duration of the procedure. ICE is an important modality for the performance of the transseptal punctures, and some centers use ICE to monitor the left atrium and PV during the ablation; however, its usefulness is very operator-dependent and requires additional vascular access. Gadolinium-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) has been utilized to depict the anatomy of left atrium and PVs; however, these images are typically not as high quality as the MDCT images with limited out of plane spatial resolution, and AF patients sometimes have pacemakers and/or defibrillators which make performance of the MRA problematic.
Prior studies have compared MDCT favorably with other modalities such as fluoroscopy, TEE, ICE, and MRI.41–43 MDCT angiography showed equivalent diagnostic value to ICE in depicting supernumerary PVs,41 without the user-dependent problems with ICE. In addition, by head to head comparison, MDCT was superior to fluoroscopy, TEE, and ICE to depict the numbers of PV ostia.41–43 MDCT angiography depicts the entire structure of each PV better than ICE and TEE because high resolution MDCT can obtain detailed volumetric data with 0.5 mm spatial resolution. This data can then be used to provide several types of reconstructed images and free angle images such as 3D or multiplanar reformatted (MPR) images, which can show precise en face image of ostia. However, both TEE and ICE imaging have the advantage of continuous, real-time imaging during the procedure, which is not possible for MDCT.
Several studies have established the utility of cardiac MDCT angiography to show the anatomy of left atrium and PVs before RFCA.13,41,44 The precise measurement of PVs was first performed with MRI.40,45–47 MRI has good spatial resolution and coverage so that it could provide defining size, shape, and anatomy of each PV and its relationship to other atrial structures. The minimum pulmonary ostial diameters occur during atrial systole and the maximum diameters occur during late atrial diastole. These phase differences showed a 32.5% difference in PV ostial diameters, which was assessed by steady-state free precession cine MRI.48,49 MDCT, even if non-ECG-gated MDCT angiography was used, can depict the entire anatomy of left atrium and PVs but it can not be determined the phase or phases of cardiac cycle by this method. ECG-gated MDCT angiography should be used to determine the precise dimension using absolute reconstruction method, although this is not possible if the patient is in AF at the time of the scan.
MDCT provides the additional advantage that it is operator-independent, unlike the other modalities (with the exception of MRI). The 3D reconstructed image is the most important image for the electrophysiologist. Demonstration of the complex left atrium and PV anatomy enables the operator to perform specific catheter selection and approach to ablation. This preprocedure knowledge may reduce not only the overall radiation dose but also procedure time during the RFCA. In general, the radiation dose delivered during RFCA for AF was as two to three times higher than that of a cardiac MDCT examination.50,51 In addition, MDCT is safe for patients with implanted devices, which can be a limitation to MRI.
Image acquisition and reconstruction using 64-row multidetector computed tomography
The goal of preprocedure MDCT imaging is to delineate the left atrium and PV anatomy. Of key importance is the depiction of PV anomalies which may interfere with the RFCA for AF. MDCT scanning should be performed within 24 h of RFCA, and ideally immediately prior to RFCA, to avoid changes in left atrial volume and anatomy secondary to changes in preload and afterload conditions. ECG-gated MDCT scanning is preferred because of cardiac phase determination. Even in patients with AF at the time of scanning, ECG-gated MDCT scanning is preferred and will allow for accurate localization of the PVs.
The 16 or more row CT scanners are preferable to evaluate the cardiac anatomy because of their improved spatial and temporal resolution and coverage. These high-speed and wide-coverage MDCT scanners have the advantages of decreased cardiac motion and artifact, and improved image quality. Although MDCT scanners typically provide good image quality, motion artifact, lead artifact, and patient obesity may lower image quality.50
The dual chamber injector is preferred for administration of contrast for the MDCT angiography. Following the contrast injection, there is an immediate flush of normal saline which helps reduce the amount of artifact from contrast accumulation in the superior vena cava, right atrium, and right ventricle. The optimal timing of data acquisition is more difficult to determine in patient with AF due to variable R–R interval. The test bolus timing method or automatic triggering system varies among manufacturers, but the trigger should be placed to aortic root instead of the left atrium itself. The LAA fills late, and triggering off the aortic root allows for appendage opacification without compromising left atrial enhancement.
The following image reconstruction modes should be selected (i) 3D, volume rendering (VR) including endoscopic images, (ii) MPR image, (iii) curved planar reformatted (CPR) image, (iv) maximum intensity projection image, (v) transparent image, and (vi) cross-sectional image. Three-dimensional or VR image can provide the entire anatomy of left atrium and PV, and it depicts the transition zone between the left atrium and PVs clearly. Normally there are four PVs (right superior and inferior, and left superior and inferior), but sometimes common trunk of PVs or central PV are observed (Figure 1A). These anomalous structures can be difficult to depict at the procedure by venography. The 3D image is also suitable to assess entire anatomy of left atrium and PVs, and can be merged with the catheter-constructed EAM image for optimal use of the EAM system. The endoscopic image can show the PV ostia from the left atrium, which may provide useful information about the shape or direction of each ostia of PV (Figure 1B). The axial image, which shows broad field of view, is used for primary assessment and reconstruction. MDCT can also demonstrate unsuspected contraindications to RFCA, such as an extracardiac structure compressing left atrium (Figure 2). VR and endoscopic images are not suitable for PV measurements due to their variance by shading or transparency. MPR, CPR, and cross-sectional images are suitable for the measurement of cardiac structures such as PV ostial diameter (Figures 3 and 4). To avoid PV stenosis, the proper size of balloon-type catheter must be selected, which mean the proper measurement of ostial size is critical.37,38 To obtain the correct measurement of ostial diameter of each PV, both MPR and CPR images should be selected to show the en face ostial image. Then, ostial diameter should be measured as minor and major axes diameter by orthogonal angles (Figure 5).
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Although MDCT can provide useful information for AF ablation, the radiation dose from MDCT is significant, and every effort should be made to minimize this. The radiation dose of MDCT angiography is
20 mSv with ECG-gated and non-dose modulation. Several studies reported some effective method to reduce the radiation dose using (i) low kilovoltage setting, (ii) automatic ECG-pulsed tube current modulation, (iii) dose modulation with mid-diastole, (iv) prospective gating, (v) non-ECG-gating, (vi) special filtering, (vii) pitch change with heart rate, and (viii) area detector.52–56 The range of radiation dose reduction varies from 10 to 88% according to each method. At our centre, we currently use 320-row MDCT with prospective ECG gating to reduce the radiation dose.
The therapeutic strategy of catheter-based radio frequency ablation for atrial fibrillation using multidetector computed tomography
Imaging methods such as MRI, MDCT angiography, and ICE can be integrated with EAM system and guiding technology.29,30 Both EAM data and VR image from MRI or MDCT angiography are ‘integrated’ into a single image, which is used in the EAM system to help guide RFCA. This integrated system likely increases the efficacy of RFCA for AF. MDCT image integration can reduce the fluoroscopic time, and improve outcomes.27,57 The improved visualization of complex left atrium and PV anatomy can be a great help for the AF ablation. There are other MDCT integration systems with non-contact mapping and 3D MDCT imaging.27 These systems also require high-quality preprocedural imaging to define the left atrial anatomy, for which MDCT angiography is well-suited (Figure 6). Although the image integration system can provide effective information as real-time guide for RFCA, care must always be taken to remember that the MDCT image is preacquired and static, and that failures of adequate registration do occur. Risk factors for poor registration include large left atrial size, and changes in volume status, but not rhythm status.58 One randomized study has reported the superiority of MDCT angiography and fluoroscopy image real-time integration which reduced fluoroscopic and procedural time.28
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Post-procedure assessment
Post-procedural complications including pleural or pericardial effusions and PV stenosis can be evaluated by MDCT.12
,13 Among these, PV stenosis is a known complication of RFCA of AF, and may be asymptomatic or cause shortness of breath, chest pain, or hemoptysis. This is typically caused by excessive ablation inside the vein. It is difficult to identify the precise venoatrial junction by fluoroscopy or by electrogram signal during the procedure, and thus some inadvertent ablation inside the vein may occur.59,60 In patients with symptoms possibly referable to PV stenosis following an RFCA for AF procedure, repeat MDCT, using the identical technique to the preprocedure scan, is indicated.61 These MDCT images should be able to non-invasively depict any ostial diameter change.
New technology computed tomography imaging for catheter-based radio frequency ablation
Recently, the introduction of wide-area detector or dynamic volume scanners, such as the 320-row MDCT scanner (Aquilion one, Toshiba, Otawara, Japan) provide full cardiac coverage enabling whole heart image without helical scanning. This new technology may reduce not only radiation dose less than one-fourth of that for a typical MDCT scan, but also total amount of contrast material needed for ECG-gated CT scanning. In conventional scanners, the image quality of the left atrium and PVs are limited by left ventricular ejection fraction, left ventricular dimension, and the size of left atrium. In patients with a dilated left ventricle and atrium, the visualization of the left atrium and PVs is sometimes difficult and may underestimate their size. One rotation is enough to obtain the whole heart dataset. It may also provide other important information such as the presence of coronary artery disease, previous myocardial infarction, and left ventricular dysfunction. Furthermore, whole heart imaging in a single heart beat or less allows the potential for accurate imaging in the presence of arrhythmias.
Alternatively, the dual-source CT (DSCT) scanner is an effective diagnostic tool due to its very high temporal resolution that provides clear left atrium and PV images.62 In addition, preliminary evidence suggests that DSCT may be an accurate tool for the assessment of cardiac disease, even in patients with AF.63
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Multidetector computed tomography has many uses within cardiovascular medicine. It is well suited for pre-procedure imaging for ablation of AF. The assessment of PV anatomy and the MDCT image integration into the EAM are helping to improve the efficacy and safety of PV isolation for curative treatment of AF.
Conflict of interest: R.T.G. is a member of Speakers Bureau and received research support from Toshiba. J.A.C.L. received grant support from Toshiba and Bracco.
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[1] Feinberg WM, Cornell ES, Nightingale SD, Pearce LA, Tracy RP, Hart RG, et al. Relationship between prothrombin activation fragment F1.2 and international normalized ratio in patients with atrial fibrillation. Stroke Prevention in Atrial Fibrillation Investigators. Stroke (1997) 28:1101–6.
[2] Ostrander LD Jr, Brandt RL, Kjelsberg MO, Epstein FH. Electrocardiographic findings among the adult population of a Total Natural Community, Tecumseh, Michigan. Circulation (1965) 31:888–98.
[3] Falk RH. Atrial fibrillation. N Engl J Med (2001) 344:1067–78.
[4] Furberg CD, Psaty BM, Manolio TA, Gardin JM, Smith VE, Rautaharju PM. Prevalence of atrial fibrillation in elderly subjects (the Cardiovascular Health Study). Am J Cardiol (1994) 74:236–41.[CrossRef][Web of Science][Medline]
[5] Heeringa J, van der Kuip DA, Hofman A, Kors JA, van Herpen G, Stricker BH, et al. Prevalence, incidence and lifetime risk of atrial fibrillation: the Rotterdam study. Eur Heart J (2006) 27:949–53.
[6] Black IW, Hopkins AP, Lee LC, Walsh WF. Evaluation of transesophageal echocardiography before cardioversion of atrial fibrillation and flutter in nonanticoagulated patients. Am Heart J (1993) 126:375–81.[CrossRef][Web of Science][Medline]
[7] Fuster V, Ryden LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation (2006) 114:e257–e354.
[8] Goldstein LB, Adams R, Alberts MJ, Appel LJ, Brass LM, Bushnell CD, et al. Primary prevention of ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council: cosponsored by the Atherosclerotic Peripheral Vascular Disease Interdisciplinary Working Group; Cardiovascular Nursing Council; Clinical Cardiology Council; Nutrition, Physical Activity, and Metabolism Council; and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation (2006) 113:e873–e923.
[9] Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham study. Stroke (1991) 22:983–8.
[10] Wolf PA, D'Agostino RB, Belanger AJ, Kannel WB. Probability of stroke: a risk profile from the Framingham study. Stroke (1991) 22:312–8.
[11] Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med (1998) 339:659–66.
[12] Ghaye B, Szapiro D, Dacher JN, Rodriguez LM, Timmermans C, Devillers D, et al. Percutaneous ablation for atrial fibrillation: the role of cross-sectional imaging. Radiographics (2003) 23:S19–33. discussion: S48–50.
[13] Lacomis JM, Wigginton W, Fuhrman C, Schwartzman D, Armfield DR, Pealer KM. Multi-detector row CT of the left atrium and pulmonary veins before radio-frequency catheter ablation for atrial fibrillation. Radiographics (2003) 23:S35–48. discussion: S48–50.
[14] Nathan H, Eliakim M. The junction between the left atrium and the pulmonary veins. An anatomic study of human hearts. Circulation (1966) 34:412–22.
[15] Chen SA, Tai CT, Yu WC, Chen YJ, Tsai CF, Hsieh MH, et al. Right atrial focal atrial fibrillation: electrophysiologic characteristics and radiofrequency catheter ablation. J Cardiovasc Electrophysiol (1999) 10:328–35.[Web of Science][Medline]
[16] Nademanee K, McKenzie J, Kosar E, Schwab M, Sunsaneewitayakul B, Vasavakul T, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol (2004) 43:2044–53.
[17] Nademanee K, Schwab MC, Kosar EM, Karwecki M, Moran MD, Visessook N, et al. Clinical outcomes of catheter substrate ablation for high-risk patients with atrial fibrillation. J Am Coll Cardiol (2008) 51:843–9.
[18] Cox JL, Boineau JP, Schuessler RB, Kater KM, Lappas DG. Five-year experience with the maze procedure for atrial fibrillation. Ann Thorac Surg (1993) 56:814–23. discussion: 823–814.[Abstract]
[19] Haissaguerre M, Gencel L, Fischer B, Le Metayer P, Poquet F, Marcus FI, et al. Successful catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol (1994) 5:1045–52.[Web of Science][Medline]
[20] Mangrum JM, Mounsey JP, Kok LC, DiMarco JP, Haines DE. Intracardiac echocardiography-guided, anatomically based radiofrequency ablation of focal atrial fibrillation originating from pulmonary veins. J Am Coll Cardiol (2002) 39:1964–72.
[21] Ren JF, Lin D, Marchlinski FE, Callans DJ, Patel V. Esophageal imaging and strategies for avoiding injury during left atrial ablation for atrial fibrillation. Heart Rhythm (2006) 3:1156–61.[Web of Science][Medline]
[22] Tracy CM. Use of ICE for RF ablation of AF. J Cardiovasc Electrophysiol (2006) 17:78–9.[Web of Science][Medline]
[23] Verma A, Marrouche NF, Natale A. Pulmonary vein antrum isolation: intracardiac echocardiography-guided technique. J Cardiovasc Electrophysiol (2004) 15:1335–40.[CrossRef][Web of Science][Medline]
[24] Oral H, Scharf C, Chugh A, Hall B, Cheung P, Good E, et al. Catheter ablation for paroxysmal atrial fibrillation: segmental pulmonary vein ostial ablation versus left atrial ablation. Circulation (2003) 108:2355–60.
[25] Packer DL, Keelan P, Munger TM, Breen JF, Asirvatham S, Peterson LA, et al. Clinical presentation, investigation, and management of pulmonary vein stenosis complicating ablation for atrial fibrillation. Circulation (2005) 111:546–54.
[26] Arentz T, Weber R, Burkle G, Herrera C, Blum T, Stockinger J, et al. Small or large isolation areas around the pulmonary veins for the treatment of atrial fibrillation? Results from a prospective randomized study. Circulation (2007) 115:3057–63.
[27] Kistler PM, Rajappan K, Jahngir M, Earley MJ, Harris S, Abrams D, et al. The impact of CT image integration into an electroanatomic mapping system on clinical outcomes of catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol (2006) 17:1093–101.[CrossRef][Web of Science][Medline]
[28] Sra J, Narayan G, Krum D, Malloy A, Cooley R, Bhatia A, et al. Computed tomography-fluoroscopy image integration-guided catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol (2007) 18:409–14.[CrossRef][Web of Science][Medline]
[29] Dong J, Calkins H, Solomon SB, Lai S, Dalal D, Lardo AC, et al. Integrated electroanatomic mapping with three-dimensional computed tomographic images for real-time guided ablations. Circulation (2006) 113:186–94.
[30] Dong J, Dickfeld T, Dalal D, Cheema A, Vasamreddy CR, Henrikson CA, et al. Initial experience in the use of integrated electroanatomic mapping with three-dimensional MR/CT images to guide catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol (2006) 17:459–66.[CrossRef][Web of Science][Medline]
[31] Chen MS, Marrouche NF, Khaykin Y, Gillinov AM, Wazni O, Martin DO, et al. Pulmonary vein isolation for the treatment of atrial fibrillation in patients with impaired systolic function. J Am Coll Cardiol (2004) 43:1004–9.
[32] Di Biase L, Fahmy TS, Wazni OM, Bai R, Patel D, Lakkireddy D, et al. Pulmonary vein total occlusion following catheter ablation for atrial fibrillation: clinical implications after long-term follow-up. J Am Coll Cardiol (2006) 48:2493–9.
[33] Sacher F, Monahan KH, Thomas SP, Davidson N, Adragao P, Sanders P, et al. Phrenic nerve injury after atrial fibrillation catheter ablation: characterization and outcome in a multicenter study. J Am Coll Cardiol (2006) 47:2498–503.
[34] Gottlieb I, Pinheiro A, Brinker JA, Corretti MC, Mayer SA, Bluemke DA, et al. Diagnostic accuracy of arterial phase 64-slice multidetector CT angiography for left atrial appendage thrombus in patients undergoing atrial fibrillation ablation. J Cardiovasc Electrophysiol (2008) 19:247–51.[CrossRef][Web of Science][Medline]
[35] Kim YY, Klein AL, Halliburton SS, Popovic ZB, Kuzmiak SA, Sola S, et al. Left atrial appendage filling defects identified by multidetector computed tomography in patients undergoing radiofrequency pulmonary vein antral isolation: a comparison with transesophageal echocardiography. Am Heart J (2007) 154:1199–205.[CrossRef][Web of Science][Medline]
[36] Achenbach S, Ropers D, Regenfus M, Muschiol G, Daniel WG, Moshage W. Contrast enhanced electron beam computed tomography to analyse the coronary arteries in patients after acute myocardial infarction. Heart (2000) 84:489–93.
[37] Nakagawa H, Antz M, Wong T, Schmidt B, Ernst S, Ouyang F, et al. Initial experience using a forward directed, high-intensity focused ultrasound balloon catheter for pulmonary vein antrum isolation in patients with atrial fibrillation. J Cardiovasc Electrophysiol (2007) 18:136–44.[CrossRef][Web of Science][Medline]
[38] Schmidt B, Antz M, Ernst S, Ouyang F, Falk P, Chun JK, et al. Pulmonary vein isolation by high-intensity focused ultrasound: first-in-man study with a steerable balloon catheter. Heart Rhythm (2007) 4:575–84.[CrossRef][Web of Science][Medline]
[39] Champagne J, Echahidi N, Philippon F, St-Pierre A, Molin F, Blier L, et al. Usefulness of transesophageal echocardiography in the isolation of pulmonary veins in the treatment of atrial fibrillation. Pacing Clin Electrophysiol (2007) 30:S116–S119.[Medline]
[40] Kato R, Lickfett L, Meininger G, Dickfeld T, Wu R, Juang G, et al. Pulmonary vein anatomy in patients undergoing catheter ablation of atrial fibrillation: lessons learned by use of magnetic resonance imaging. Circulation (2003) 107:2004–10.
[41] Jongbloed MR, Bax JJ, Lamb HJ, Dirksen MS, Zeppenfeld K, van der Wall EE, et al. Multislice computed tomography versus intracardiac echocardiography to evaluate the pulmonary veins before radiofrequency catheter ablation of atrial fibrillation: a head-to-head comparison. J Am Coll Cardiol (2005) 45:343–50.
[42] Schwartzman D, Lacomis J, Wigginton WG. Characterization of left atrium and distal pulmonary vein morphology using multidimensional computed tomography. J Am Coll Cardiol (2003) 41:1349–57.
[43] Wood MA, Wittkamp M, Henry D, Martin R, Nixon JV, Shepard RK, et al. A comparison of pulmonary vein ostial anatomy by computerized tomography, echocardiography, and venography in patients with atrial fibrillation having radiofrequency catheter ablation. Am J Cardiol (2004) 93:49–53.[Web of Science][Medline]
[44] Stanford W, Breen JF. CT evaluation of left atrial pulmonary venous anatomy. Int J Cardiovasc Imaging (2005) 21:133–9.[CrossRef][Web of Science][Medline]
[45] Tsao HM, Yu WC, Cheng HC, Wu MH, Tai CT, Lin WS, et al. Pulmonary vein dilation in patients with atrial fibrillation: detection by magnetic resonance imaging. J Cardiovasc Electrophysiol (2001) 12:809–13.[CrossRef][Web of Science][Medline]
[46] Wilber DJ, Kall JG, Cooke PA. Electroanatomic imaging using magnetic catheter tracking in the diagnosis and treatment of atrial arrhythmias. J Electrocardiol (1998) 31:92–100.[CrossRef][Web of Science][Medline]
[47] Wittkampf FH, Vonken EJ, Derksen R, Loh P, Velthuis B, Wever EF, et al. Pulmonary vein ostium geometry: analysis by magnetic resonance angiography. Circulation (2003) 107:21–3.
[48] Lickfett L, Dickfeld T, Kato R, Tandri H, Vasamreddy CR, Berger R, et al. Changes of pulmonary vein orifice size and location throughout the cardiac cycle: dynamic analysis using magnetic resonance cine imaging. J Cardiovasc Electrophysiol (2005) 16:582–8.[CrossRef][Web of Science][Medline]
[49] Choi SI, Seo JB, Choi SH, Lee SH, Do KH, Ko SM, et al. Variation of the size of pulmonary venous ostia during the cardiac cycle: optimal reconstruction window at ECG-gated multi-detector row CT. Eur Radiol (2005) 15:1441–5.[CrossRef][Web of Science][Medline]
[50] Ector J, Dragusin O, Adriaenssens B, Huybrechts W, Willems R, Ector H, et al. Obesity is a major determinant of radiation dose in patients undergoing pulmonary vein isolation for atrial fibrillation. J Am Coll Cardiol (2007) 50:234–42.
[51] Efstathopoulos EP, Katritsis DG, Kottou S, Kalivas N, Tzanalaridou E, Giazitzoglou E, et al. Patient and staff radiation dosimetry during cardiac electrophysiology studies and catheter ablation procedures: a comprehensive analysis. Europace (2006) 8:443–8.
[52] Abada HT, Larchez C, Daoud B, Sigal-Cinqualbre A, Paul JF. MDCT of the coronary arteries: feasibility of low-dose CT with ECG-pulsed tube current modulation to reduce radiation dose. AJR Am J Roentgenol (2006) 186:S387–S390.
[53] Husmann L, Valenta I, Gaemperli O, Adda O, Treyer V, Wyss CA, et al. Feasibility of low-dose coronary CT angiography: first experience with prospective ECG-gating. Eur Heart J (2008) 29:191–7.
[54] Wierzbicki M, Guiraudon GM, Jones DL, Peters T. Dose reduction for cardiac CT using a registration-based approach. Med Phys (2007) 34:1884–95.[CrossRef][Web of Science][Medline]
[55] Hur G, Hong SW, Kim SY, Kim YH, Hwang YJ, Lee WR, et al. Uniform image quality achieved by tube current modulation using SD of attenuation in coronary CT angiography. AJR Am J Roentgenol (2007) 189:188–96.
[56] McCollough CH, Primak AN, Saba O, Bruder H, Stierstorfer K, Raupach R, et al. Dose performance of a 64-channel dual-source CT scanner. Radiology (2007) 243:775–84.
[57] Martinek M, Nesser HJ, Aichinger J, Boehm G, Purerfellner H. Impact of integration of multislice computed tomography imaging into three-dimensional electroanatomic mapping on clinical outcomes, safety, and efficacy using radiofrequency ablation for atrial fibrillation. Pacing Clin Electrophysiol (2007) 30:1215–23.[CrossRef][Medline]
[58] Dong J, Dalal D, Scherr D, Cheema A, Nazarian S, Bilchick K, et al. Impact of heart rhythm status on registration accuracy of the left atrium for catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol (2007) 18:1269–76.[CrossRef][Web of Science][Medline]
[59] Perez-Castellano N, Villacastin J, Moreno J, Rodriguez A, Moreno M, Conde A, et al. Errors in pulmonary vein identification and ostia location in the absence of pulmonary vein imaging. Heart Rhythm (2005) 2:1082–9.[CrossRef][Web of Science][Medline]
[60] Piorkowski C, Hindricks G, Schreiber D, Tanner H, Weise W, Koch A, et al. 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. Heart Rhythm (2006) 3:317–27.[CrossRef][Web of Science][Medline]
[61] Calkins H, Brugada J, Packer DL, Cappato R, Chen SA, Crijns HJ, et al. HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up. A report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation developed in partnership with the European Heart Rhythm Association (EHRA) and the European Cardiac Arrhythmia Society (ECAS); in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Endorsed and approved by the governing bodies of the American College of Cardiology, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, and the Heart Rhythm Society. Europace (2007) 9:335–79.
[62] Kobza R, Auf der Maur C, Kurtz C, Hoffmann A, Allgayer B, et al. Esophagus imaging for radiofrequency ablation of atrial fibrillation using a dual-source computed tomography system: preliminary observations. J Interv Card Electrophysiol (2007) 19:167–70.[CrossRef][Web of Science][Medline]
[63] Oncel D, Oncel G, Tastan A. Effectiveness of dual-source CT coronary angiography for the evaluation of coronary artery disease in patients with atrial fibrillation: initial experience. Radiology (2007) 245:703–11.
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