Ectopic and reentrant activation patterns in the posterior left atrium during stretch-related atrial fibrillation
ABSTRACT Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is predicted to dramatically increase its prevalence in the future. There is experimental evidence that increasing stretch increases the dominance of the pulmonary veins (PVs) during AF in isolated hearts and ectopic activity in the isolated PVs, but the ionic mechanisms underlying such effects are not clear and the ability of the PVs to favorably host functional reentry during stretch cannot be excluded. We used a combination of endocardial-epicardial optical mapping with phase and spectral analysis to study stretch-related AF (SRAF) in normal isolated sheep hearts. We have found rapid AF sources in the posterior left atrium (PLA) and PV region and their activation frequency and level of organization correlated with intra-atrial pressure. Analysis of the surfaces' optical mapping data in the phase domain reveals that activation of the PLA consisted of alternating patterns of breakthroughs, reentries and relatively simple waves swiping across the mapped field. The patterns on the endocardial and epicardial PLA surface at any given moment of time of the SRAF could be either identical or not identical, and the activity in the thickness of the PLA wall is hypothesized to conform to either ectopic discharge or scroll waves, but a definite evidence for the presence of such mechanisms is currently lacking. Thus the understanding of the manner by which the mechano-electric feedback effects in the PLA, including the PVs, become important in the initiation and maintenance of AF requires further detailed investigation.
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ABSTRACT: Objective: To study the clinical efficacy of catheter ablation for paroxysmal atrial fibrillation (AF) in patients with a permanent pacemaker (PM) for sick sinus syndrome (SSS). Methods: Our prospectively established database of patients who underwent circumferential pulmonary vein (PV) ablation for paroxysmal AF was retrospectively reviewed. A total of 41 patients with a permanent PM for the treatment of SSS (SSS+PM group) and 123 age- and gender-matched control subjects (on a 1: 3 basis) without SSS or a permanent PM (no-SSS+no-PM group) were included in this study. AF recurrence was defined as the occurrence of confirmed atrial tachyarrhythmia lasting more than 30 seconds beyond three months after catheter ablation in the absence of any antiarrhythmic treatment. Results: During a mean follow-up period of 18.3±10.6 months (range 3-30 months), 50 patients (30.5%) developed recurrence of AF. The recurrence rate was higher in the SSS+PM group than in the no-SSS+no-PM group (43.9% vs. 26.3%, p=0.011). A Cox regression analysis adjusted for age, valvular heart disease, left atrial (LA) diameter and PV isolation identified only SSS and the use of a PM together as an independent predictor of recurrence of AF (hazard ratio 2.02, 95% confidence interval 1.10-3.69, p=0.023). Conclusion: Patients with a permanent PM for SSS are at an increased risk of recurrence of AF after catheter ablation.Internal Medicine 10/2013; 52(20):2305-2310. DOI:10.2169/internalmedicine.52.0982 · 0.90 Impact Factor
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ABSTRACT: Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems". Background: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is predicted to dramatically increase its prevalence in the future. High-resolution mapping data and Fourier power spectral analysis with its dominant frequency support the hypothesis that AF in the structurally normal sheep heart and in some patients often presents organized drivers in the form of periodic surface re-entries or breakthroughs. Nevertheless, the dynamics of those surface patterns of activity, as well as their intramural components are still poorly understood. Objective: To present data on AF waves from the surface of isolated sheep hearts and discuss the interpretation of their intramural patterns. Methods: We used a combination of endocardial-epicardial optical mapping with phase and spectral analysis as well as computer simulation of the re-entrant activity in the myocardial wall. Results: Analysis of the surfaces' optical mapping data in the phase domain reveals that activation of the posterior left atrium (PLA) consisted of alternating patterns of breakthroughs and reentries. The patterns on the endocardial and epicardial PLA surface at any given moment of time of the AF could be either identical or not identical, and the activity in the thickness of the PLA wall is hypothesized to conform to either ectopic discharge or reentrant scroll waves, but a definite evidence for the presence of such mechanisms is currently lacking. A universal minimal-principle theory is shown in a computer model to result in a tendency of the axis of the scroll waves to align with the myocardial fibers inside the wall. Conclusion: The tendency of filaments of scroll waves to align with myocardial fibers may contribute to the variety and intermittency of surface rotors seen in AF.Methods of Information in Medicine 05/2014; 53(4). DOI:10.3414/ME13-02-0047 · 2.25 Impact Factor
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ABSTRACT: In this issue of Circulation, readers will find a fascinating study presented by Dr. Haissaguerre and several members of a promising and newly erected Institute for Cardiovascular Research located in Bordeaux (France): the LIRYC, ("L'institut de Rythmologie de Modélisation Cardiaque", The Institute for Arrhythmia and Computer Modeling Research).(1) This is yet another pioneering contribution from the Bordeaux group which, if confirmed, may improve the management of patients with persistent atrial fibrillation (AF). AF is commonly classified as paroxysmal (PAF) or persistent (PsAF), depending on the duration of the arrhythmic episodes, fewer or more than 7 days.(2) PsAF may also be sub-classified as long-standing persistent (LPsAF) when fibrillation has been continuous for more than a year.(2) In the late nineties, Dr. Haissaguerre and team's seminal work indicated that, in patients with PAF, a catheter ablation procedure may be targeted at discrete pulmonary vein (PV) electrical foci and that PV electrical isolation from the remainder of the atrial muscle may prevent AF re-initiation.(3,4) While the exact nature of PV foci has never been fully elucidated, this procedure proved successful in terminating AF, and in preventing its recurrence.(5,6.)Circulation 07/2014; 130(7). DOI:10.1161/CIRCULATIONAHA.114.011635 · 14.43 Impact Factor