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Ablation Strategies (ablation + strategy)
Selected AbstractsAbout Electrograms and Their Structural Origin: Clues To More Effective Ablation Strategies for Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2002HEIN HEIDBUCHEL M.D., Ph.D.Article first published online: 12 AUG 200 [source] Dynamic Registration of Preablation Imaging With a Catheter Geometry to Guide Ablation in a Swine Model: Validation of Image Integration and Assessment of Catheter Navigation AccuracyJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2010J. JASON WEST M.D. Image Integration with a Catheter Mapping System.,Background: Catheter ablation of atrial and ventricular tachyarrhythmia involves anatomically based cardiac ablation strategies. CT and MRI images provide the most detailed cardiac anatomy available. Integration of these images into a mapping system should produce detailed and accurate models suitable to guide ablation. Objective: The purpose of this study was to validate and assess the accuracy of a novel CT and MRI image integration algorithm designed to facilitate catheter navigation and ablation. Methods: Using a lateral thoracotomy, markers were sutured to the epicardial surface of each cardiac chamber in 12 swine. Detailed CT/MRI anatomy was imported into the mapping system. The CT/MRI image was then integrated with a detailed catheter geometry of the relevant chamber using a new image integration algorithm. The epicardial markers, identified from the CT/MRI images, were then displayed on the surface of the integrated image. Guided only by the integrated CT/MRI, a single RF lesion was directed at the corresponding endocardial site for each epicardial marker. At autopsy, the distance from the endocardial RF lesion to the target site was assessed. Results: The mean position error (CT/MRI) for the left atrium was 2.5 ± 2.4 mm/5.1 ± 3.9 mm, for the right atrium 6.2 ± 6.5 mm/4.3 ± 2.2 mm, for the right ventricle 6.2 ± 4.3 mm/6.6 ± 5.3 mm, and for the left ventricle 4.7 ± 3.4 mm/3.1 ± 2.7 mm. There was no cardiac perforation or tamponade. Conclusion: CT and MRI images can be effectively utilized for catheter navigation when integrated into a mapping system. This novel registration module with dynamic registration provides effective guidance for ablation. (J Cardiovasc Electrophysiol, Vol. 21, pp. 81,87, January 2010) [source] State of the Art: Catheter Ablation of Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2008MATTHEW WRIGHT M.B.B.S., Ph.D. Curative treatment of atrial fibrillation with catheter ablation is now a legitimate option for a large number of patients. In the last decade a tremendous amount has been discovered about this fascinating arrhythmia, yet there is still much that is understood. A number of different ablation strategies have been used including pulmonary vein isolation, targeting of fractionated electrograms, compartmentalising the atria with linear lesions and various combinations and modifications of these lesion sets. The optimal ablation strategy for both paroxysmal and long-lasting persistent atrial fibrillation is unknown. In this review the possible mechanisms underlying atrial fibrillation are examined along with the current catheter ablation techniques used in the treatment atrial fibrillation. [source] Clinical outcomes of corneal wavefront customized ablation strategies with SCHWIND CAM in LASIK treatmentsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2009Maria Clara Arbelaez Abstract Purpose:, To evaluate the clinical outcomes of aspheric corneal wavefront (CW) ablation profiles in LASIK treatments. Methods:, Thirty eyes treated with CW ablation profiles were included after a follow-up of 6 months. In all cases, standard examinations including preoperative and postoperative wavefront analysis with a CW topographer (Optikon Keratron Scout) were performed. Custom Ablation Manager (CAM) software was used to plan corneal wavefront customized aspheric treatments, and the ESIRIS flying spot excimer laser system was used to perform the ablations (both SCHWIND eye-tech-solutions, Kleinhostheim, Germany). Clinical outcomes were evaluated in terms of predictability, refractive outcome, safety, and wavefront aberration. Results:, In general, the postoperative uncorrected visual acuity and the best corrected visual acuity improved (p < 0.001). In particular, the trefoil, coma, and spherical aberrations, as well as the total root-mean-square values of higher order aberrations, were significantly reduced (p < 0.05) when the pre-existing aberrations were greater than the repeatability and the biological noise. Conclusions:, The study results indicate that the aspheric corneal wavefront customized CAM approach for planning ablation volumes yields visual, optical, and refractive results comparable to those of other wavefront-guided customized techniques for correction of myopia and myopic astigmatism. The CW customized approach shows its strength in cases where abnormal optical systems are expected. Apart from the risk of additional ablation of corneal tissue, systematic wavefront-customized corneal ablation can be considered as a safe and beneficial method. [source] Accurate U-Pb Age and Trace Element Determinations of Zircon by Laser Ablation-Inductively Coupled Plasma-Mass SpectrometryGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 3 2004Honglin Yuan LA-ICP-MS; laser excimer; zircon; géochronologie; éléments en trace Various zircons of Proterozoic to Oligocene ages (1060-31 Ma) were analysed by laser ablation-inductively coupled plasma-mass spectrometry. Calibration was performed using Harvard reference zircon 91500 or Australian National University reference zircon TEMORA 1 as external calibrant. The results agree with those obtained by SIMS within 2s error. Twenty-four trace and rare earth elements (P, Ti, Cr, Y, Nb, fourteen REE, Hf, Ta, Pb, Th and U) were analysed on four fragments of zircon 91500. NIST SRM 610 was used as the reference material and 29Si was used as internal calibrant. Based on determinations of four fragments, this zircon shows significant intra-and inter-fragment variations in the range from 10% to 85% on a scale of 120 ,m, with the variation of REE concentrations up to 38.7%, although the chondrite-normalised REE distributions are very similar. In contrast, the determined age values for zircon 91500 agree with TIMS data and are homogeneous within 8.7 Ma (2s). A two-stage ablation strategy was developed for optimising U-Pb age determinations with satisfactory trace element and REE results. The first cycle of ablation was used to collect data for age determination only, which was followed by continuous ablation on the same spot to determine REE and trace element concentrations. Based on this procedure, it was possible to measure zircon ages as low as 30.37 0.39 Ma (MSWD = 1.4; 2s). Other examples for older zircons are also given. Différents zircons d'âges variant du Protérozoïque à l'Oligocène (1060-31 Ma) ont été analysés par spectrométrie avec source à plasma induit et ablation laser. La calibration a été faite en utilisant le zircon 91500 de référence de Harvard ou le zircon TEMORA 1 de référence de l'Université Nationale Australienne comme calibrant externe. Les résultats sont en accord avec ceux obtenus par SIMS aux erreurs analytiques près (2s). Vingt-quatre éléments en trace et Terres Rares (P, Ti, Cr, Y, Nb, quatorze ETR, Hf, Ta, Pb, Th et U) ont été analysés sur quatre fragments du zircon 91500. Le standard SRM 610 de NIST a été utilisé comme matériau de référence et 29Si comme calibrant interne. À partir des déterminations faites sur ces quatre fragments, ce zircon montre des variations intra et inter fragments de l'ordre de 10%à 85%à une échelle de 120 ,m, avec des variations des concentrations de Terres Rares allant jusquà 38.7%, bien que le spectre de Terres Rares normalisé aux chondrites reste très constant. Au contraire, les âges déterminés pour le zircon 91500 sont en accord avec les résultats de TIMS et sont homogènes à 8.7 Ma près (2s). Une stratégie d'ablation en deux étapes a été développée pour optimiser les déterminations d'âges U-Pb, et avoir des résultats de Terres Rares et d'éléments en trace satisfaisants. Le premier cycle d'ablation était utilisé pour collecter les données nécessaires à la détermination de l'âge seulement et était suivi d'un cycle d'ablation continue sur le même spot, pour déterminer les concentrations en Terres Rares et en éléments en trace. Grâce à cette procédure, il a été possible de mesurer des âges sur zircons aussi récents que 30.37 0.39 Ma (MSWD = 1.4; 2s). D'autres exemples sur des zircons plus vieux sont aussi donnés. [source] Fibrillating Areas Isolated within the Left Atrium after Radiofrequency Linear Catheter AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2006THOMAS ROSTOCK M.D. Introduction: Nonpulmonary vein sources have been implicated as potential drivers of atrial fibrillation (AF). This observational study describes regions of fibrillating atrial tissue isolated inadvertently from the left atrium (LA) following linear catheter ablation for AF. Methods and Results: We report four patients with persistent/permanent AF who underwent pulmonary vein isolation with additional linear lesions and who presented with recurrent AF (mean AF cycle length [AFCL] 175,270 ms). Further catheter ablation resulted in the inadvertent electrical isolation of significant areas of the LA in which AF persisted at the same AFCL as was measured prior to disconnection, despite the restoration of sinus rhythm (SR) in all other left and right atrial areas, strongly suggesting that these islands were driving the remaining atria into fibrillation. The disconnected areas were located in the lateral LA, including the left atrial appendage (LAA) in three patients (limited to the LAA in one) and in the posterior LA in one patient. These isolated fibrillating regions represented 15,24% of the global LA surface, as estimated by electroanatomic mapping. Conclusion: Fibrillation can be maintained within electrically isolated regions of the LA following catheter ablation of AF, demonstrating the importance of atrial drivers in the maintenance of AF. Further mapping of these drivers is needed to characterize their mechanism and thereby allow for a more specific ablation strategy. [source] | ||||||||||