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      Electrophysiological Mapping and Histological Examinations of the Swine Atrium with Sustained (≥24 h) Atrial Fibrillation: A Suitable Animal Model for Studying Human Atrial Fibrillation

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          Abstract

          Objectives: Interventional elimination of chronic persistent atrial fibrillation (AFib) remains difficult. An animal model mimicking the clinical situation is important. Methods and Results: Twenty-five adult pigs were implanted with a high-speed atrial pacemaker. After continuous pacing at 600 bpm for 6 weeks, 20 (91%) of the 22 survivals developed sustained AFib lasting for at least 24 h. Epicardial dense mapping revealed multiple coexisting reentrant wavelets in the left and the right atrium (LA and RA, respectively; 10.6 ± 2.9 vs. 7.6 ± 2.4 wavelets/cm<sup>2</sup>/s; p < 0.002). The mean local A-A intervals were 87.2 ± 14.6 ms in the LA and 103.3 ± 19.0 ms in the RA (p < 0.0002). Acute termination of sustained AFib was successful in 3 of the 5 pigs by propafenone, but in none of the 6 by dl-sotalol. Epicardial cryothermal ablation failed to terminate any AFib by compartmentalization of the RA free wall alone (4 pigs) or together with the LA appendage (4 pigs). Electron microscopic examination demonstrated diffuse perinuclear myolysis, myofibrillar fragmentation and mitochondrial crystal disruption in the atrium. Conclusions: Pacing-induced sustained AFib (≧24 h) in adult pigs is a feasible and efficient animal model with electrophysiological and histological characteristics closely similar to those seen in humans.

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          Most cited references 3

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          Pulmonary vein isolation for paroxysmal and persistent atrial fibrillation.

          The pulmonary veins (PVs) have been demonstrated to often play an important role in generating atrial fibrillation (AF). The purpose of this study was to determine the safety and efficacy of segmental PV isolation in patients with paroxysmal or persistent AF. In 70 consecutive patients (mean age, 53 +/- 11 years) with paroxysmal (58) or persistent (12) AF, segmental PV isolation guided by ostial PV potentials was performed. The left superior, left inferior, and right superior PVs were targeted for isolation in all patients, and the right inferior PV was isolated in 20 patients. Among the 230 targeted PVs, 217 (94%) were completely isolated, with a mean of 6.5 +/- 4.2 minutes of radiofrequency energy applied at a maximum power setting of 35 W. A second PV isolation procedure was performed in 6 patients (9%). At 5 months of follow-up, 70% of patients with paroxysmal and 22% of patients with persistent AF were free from recurrent AF (P 80% of patients with paroxysmal AF. The clinical efficacy of pulmonary vein isolation is much lower when AF is persistent than when it is paroxysmal.
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            Comparison of intravenous flecainide, propafenone, and amiodarone for conversion of acute atrial fibrillation to sinus rhythm.

            In a prospective, single-blind trial, we randomized 150 consecutive symptomatic patients with acute (< or = 48 hours' duration) atrial fibrillation to receive intravenous flecainide, propafenone, or amiodarone. Flecainide and propafenone were administered as a bolus dose of 2 mg/kg in 20 minutes. A second bolus dose of 1 mg/kg in 20 minutes was administered if conversion to sinus rhythm was not achieved after 8 hours. Amiodarone was administered as a bolus of 5 mg/kg in 20 minutes followed by a continuous infusion of 50 mg/hour. By the end of a 12-hour observation period, conversion to sinus rhythm was achieved in 45 patients (90%) in the flecainide group, 36 (72%) in the propafenone group, and 32 (64%) in the amiodarone group (p = 0.008 for the overall comparison, p = 0.002 for flecainide vs amiodarone, p = 0.022 for flecainide vs propafenone, and p = 0.39 for propafenone vs amiodarone). When compared with amiodarone, this higher reversion rate with flecainide was present from the first hour of the study period. However, only after administering the second bolus was there a significant difference between flecainide and propafenone. Median time to conversion to sinus rhythm was different among groups (p < 0.001), and it was lower in the flecainide (25 minutes; range 4 to 660) and propafenone (30 minutes; range 10 to 660) groups than in the amiodarone group (333 minutes; range 15 to 710; p < 0.001 for both comparisons). Flecainide, at the doses administered in this study, is more effective than propafenone and amiodarone for conversion of acute atrial fibrillation to sinus rhythm. Propafenone and amiodarone have similar conversion rates, although propafenone was faster in achieving the conversion to sinus rhythm.
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              An 8½-Year Clinical Experience with Surgery for Atrial Fibrillation

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                Author and article information

                Journal
                CRD
                Cardiology
                10.1159/issn.0008-6312
                Cardiology
                S. Karger AG
                0008-6312
                1421-9751
                2003
                April 2003
                25 April 2003
                : 99
                : 2
                : 78-84
                Affiliations
                aDivision of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, bDepartment of Comparative Medicine, Pig Research Institute Taiwan, Chunan, and cDivisionofCardiology, DepartmentofMedicine, Veterans General Hospital, Taichung, Taiwan,ROC; dDivision of Cardiology, Texas Tech University Health Sciences Center, Lubbock,Tex.,USA
                Article
                69728 Cardiology 2003;99:78–84
                10.1159/000069728
                12711882
                © 2003 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 3, References: 21, Pages: 7
                Categories
                Arrhythmias, Electrophysiology and Electrocardiography

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