Déterminants du remodelage atrial et de son effet pro-arythmique dans la fibrillation atriale

Rational : Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. Atrial remodeling, whether electrical or structural, leads to the development of atrial cardiomyopathy. The aim of the thesis was to characterize the determinants of atrial remodeling, and their proarrhythmic effect in AF.Main results :The first part of the thesis focused on the characterization of the atrial remodeling induced by sustained atrial flutter (AFL) in a chronic canine model AFL caused electrical remodeling but no structural. In addition, AFL ablation significantly reduced arrhythmia duration but not AF vulnerability.The second part of the thesis characterized the differential role of atrial arrhythmia and ventricular response in AF-induced atrial remodeling. Lone atrial arrhythmia and lone high-rate ventricular response induced atrial remodeling. In addition, there was a synergistic effect on atrial remodeling of combined atrial arrhythmia and high ventricular rate, especially regarding fibrosis.The third part of the thesis studies the ability of cilnidipine, an N- and L-type calcium channel blocker, to alter autonomic, electrical and structural remodeling associated with chronic AF, in a subacute and chronic dog model. Cilnidipine’s electrical and structural anti-remodeling properties were associated with suppression of the changes in autonomic tone caused by AF.Conclusion - This work provides new insights into the mechanisms involved in AF-related atrial remodeling and introduces novel preventive approaches.Rationnel et objectif : La fibrillation atriale (FA) est la pathologie rythmique supra-ventriculaire la plus fréquente. Le remodelage atrial, électrique ou structurel, conduit au développement de la cardiomyopathie atriale. L’objectif est de caractériser les déterminants du remodelage atrial à l’étage supra-ventriculaire dans la FA.Principaux résultats :Le premier axe de recherche a permis d’objectiver le remodelage induit par le flutter atrial (FLA) chronique à l’aide d’un modèle chronique canin. Le FLA cause un remodelage atrial électrique mais non structurel. L’ablation du FLA diminue significativement la durée mais pas la vulnérabilité à présenter des arythmies supra-ventriculaires.Le second axe de recherche a permis de caractériser le rôle différentiel de l’arythmie atriale de la réponse ventriculaire rapide en cas de FA dans le développement du remodelage atrial. De plus, il existe un effet synergique au niveau du remodelage atrial de l’arythmie atriale et de la fréquence ventriculaire élevée en cas de FA, au niveau du processus fibrotique notamment.Le troisième axe de recherche a permis d’objectiver le rôle de la cilnidipine, un inhibiteur calcique de type N et L, dans la limitation du remodelage atrial en cas de FA chronique, à l’aide d’un modèle aigü et chronique canin, que ce soit sur son versant électrique, structurel et autonome.Conclusion – Différents facteurs, tels que le flutter atrial, l’arythmie atriale et ventriculaire en cas de FA, ont été caractérisés comme déterminants du remodelage atrial. A contrario, la modulation d’un des déterminants du remodelage atrial, le système nerveux autonome, permet de de limiter le remodelage atrial secondaire à la FA

Determinants of atrial remodeling and its proarrhythmic effect in atrial fibrillation

Rationnel et objectif : La fibrillation atriale (FA) est la pathologie rythmique supra-ventriculaire la plus fréquente. Le remodelage atrial, électrique ou structurel, conduit au développement de la cardiomyopathie atriale. L’objectif est de caractériser les déterminants du remodelage atrial à l’étage supra-ventriculaire dans la FA.Principaux résultats :Le premier axe de recherche a permis d’objectiver le remodelage induit par le flutter atrial (FLA) chronique à l’aide d’un modèle chronique canin. Le FLA cause un remodelage atrial électrique mais non structurel. L’ablation du FLA diminue significativement la durée mais pas la vulnérabilité à présenter des arythmies supra-ventriculaires.Le second axe de recherche a permis de caractériser le rôle différentiel de l’arythmie atriale de la réponse ventriculaire rapide en cas de FA dans le développement du remodelage atrial. De plus, il existe un effet synergique au niveau du remodelage atrial de l’arythmie atriale et de la fréquence ventriculaire élevée en cas de FA, au niveau du processus fibrotique notamment.Le troisième axe de recherche a permis d’objectiver le rôle de la cilnidipine, un inhibiteur calcique de type N et L, dans la limitation du remodelage atrial en cas de FA chronique, à l’aide d’un modèle aigü et chronique canin, que ce soit sur son versant électrique, structurel et autonome.Conclusion – Différents facteurs, tels que le flutter atrial, l’arythmie atriale et ventriculaire en cas de FA, ont été caractérisés comme déterminants du remodelage atrial. A contrario, la modulation d’un des déterminants du remodelage atrial, le système nerveux autonome, permet de de limiter le remodelage atrial secondaire à la FA.Rational : Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. Atrial remodeling, whether electrical or structural, leads to the development of atrial cardiomyopathy. The aim of the thesis was to characterize the determinants of atrial remodeling, and their proarrhythmic effect in AF.Main results :The first part of the thesis focused on the characterization of the atrial remodeling induced by sustained atrial flutter (AFL) in a chronic canine model AFL caused electrical remodeling but no structural. In addition, AFL ablation significantly reduced arrhythmia duration but not AF vulnerability.The second part of the thesis characterized the differential role of atrial arrhythmia and ventricular response in AF-induced atrial remodeling. Lone atrial arrhythmia and lone high-rate ventricular response induced atrial remodeling. In addition, there was a synergistic effect on atrial remodeling of combined atrial arrhythmia and high ventricular rate, especially regarding fibrosis.The third part of the thesis studies the ability of cilnidipine, an N- and L-type calcium channel blocker, to alter autonomic, electrical and structural remodeling associated with chronic AF, in a subacute and chronic dog model. Cilnidipine’s electrical and structural anti-remodeling properties were associated with suppression of the changes in autonomic tone caused by AF.Conclusion - This work provides new insights into the mechanisms involved in AF-related atrial remodeling and introduces novel preventive approaches

Co-construction d’un guide pour le diagnostic territorial des pressions etémissions agricoles

Ce numéro comprend les articles correspondant aux présentations du Colloque CIAg "Captages d’eau potable : accompagner les transitions dans les territoires agricoles" organisé à Montpellier le 11 mai 2017.As part of drinking water protection approach, the territorial diagnosis of agricultural pressures should enable stakeholders of a water catchment area (WCA) to understand the impact of agricultural activities on their water resources quality. However, a majority of theses diagnosis raises issues of relevance, stakeholder coordination, and feasibility. A method for analyzing the uses and participatory construction with the actors involved in theses diagnosis made it possible to draft a guide for the territorial diagnosis of agricultural pressures and emissions. This guide seeks to promote the coordination between actors of the WCA in order to carry out the diagnosis, invites to characterize the pressures of the main agricultural situations and if possible their emissions, and finally proposes ways of adapting to the characteristics of the territory. It aims to produce customized diagnostics, useful for the action and the decision of actors in charge of the catchments protection approach.Dans la démarche de protection des captages d’eau potable, le diagnostic territorial des pressions agricoles (DTPA) doit permettre aux acteurs d’une aire d’alimentation de captages (AAC) de comprendre l’impact des activités agricoles sur la qualité de leur ressource en eau. Or, la majorité des DTPA soulève des problèmes de pertinence, de coordination des acteurs, et de faisabilité. Une méthode d’analyse des usages et de co-construction avec les acteurs concernés a permis de rédiger un guide pour le diagnostic territorial des pressions et émissions agricoles (DTPEA). Ce guide cherche à favoriser la coordination des activités dans les AAC pour réaliser le DTPEA, invite à caractériser les pressions des principales situations agricoles et si possible leurs émissions. Il propose enfin des modalités d’adaptation du diagnostic aux caractéristiques de ces territoires. Il entend faciliter la production de diagnostics sur mesure, utiles à la décision et à l’action des acteurs en charge de la démarche de protection des captages

Tachyarrhythmias in Congenital Heart Diseases: From Ion Channels to Catheter Ablation

Major advances in pediatric cardiology in recent decades, especially surgical techniques, have resulted in an increasing number of patients with congenital heart disease (CHD) surviving to adulthood. This has generated new challenges, particularly with regards to the late onset of complex arrhythmias. Abnormal anatomy, surgical scarring, chronic hypoxemia, hemodynamic compromise, neuro-hormonal abnormalities, and genetic factors can all contribute to creating a unique substrate for arrhythmia development. This review attempts to synthesize the current state of knowledge spanning the spectrum from underlying mechanisms of arrhythmias in patients with congenital heart disease to current ablative strategies. We discuss existing knowledge gaps and highlight important areas for future research

Observations sur le même sujet

Viviand-Morel Joseph-Victor, Saint-Lager Jean, Guichard Em. Observations sur le même sujet. In: Annales de la Société botanique de Lyon, tome 6, Compte-rendu des séances – 1877-1878. 1879. pp. 165-166

Facilitated transport of diuron and glyphosate in high copper vineyard soils.

6 pagesInternational audienceThe fate of organic herbicides applied to agricultural fields may be affected by other soil amendments, such as copper applied as a fungicide. The effect of copper on the leaching of diuron and glyphosate through a granitic and a calcareous soil was studied in the laboratory using sieved-soil columns. Each soil was enriched with copper sulfate to obtain soil copper concentrations of 125, 250, 500, and 1000 mg kg(-1). Glyphosate leaching was influenced by soil pH and copper concentration, whereas diuron leaching was not. In the calcareous soil, glyphosate leaching decreased as copper levels increased from 17 mg kg(-1) (background) to 500 mg kg(-1). In the granitic soil, glyphosate leaching increased as copper levels increased from 34 mg kg(-1) (background) to 500 mg kg(-1). The shapes of the copper elution curves in presence of glyphosate were similar to shapes of the glyphosate curves, suggesting the formation of Cu-glyphosate complexes that leach through the soil. Soil copper concentration does not influence diuron leaching. In contrast, increasing copper concentrations reduces glyphosate leaching through calcareous soils, and conversely, increases glyphosate leaching through granitic soils. Our findings suggest that the risk of groundwater contamination by glyphosate increases in granitic soils with elevated copper concentrations

Does Unidirectional Block Exist after a Radiofrequency Line Creation? Insights from Ultra-High-Density Mapping (The UNIBLOCK Study)

Background: Whether unidirectional conduction block (UB) can be observed after creation of a radiofrequency (RF) line is still debated. Previous studies reported a prevalence of 9 to 33% of UB, but the assessment was performed using a point-by-point recording across the line. Ultra-high-density (UHD) system may bring some new insights on the exact prevalence of UB. Purpose: A prospective study was conducted to assess the prevalence of UB and bidirectional block (BB) using UHD system after RF line creation. Methods: Patients referred for atrial RF ablation procedure were included in this multicenter prospective study. UHD maps were performed by pacing both sides of the created line. Results: A total of 80 maps were created in 40 patients (67 ± 12 years, 70% male) by pacing (mean cycle length 600 ± 57 ms) from both sides of the cavotricuspid isthmus line. After a 47 ± 17 min waiting time after the last RF application, UHD maps (mean number of 4842 ± 5010 electrograms, acquired during 6 ± 5 min) showed that BB was unambiguously confirmed on all of them. UB was not observed in any map. After a mean follow-up of 12 ± 4 months, 6 (14%) patients experienced an arrhythmia recurrence. Conclusion: After creation of an RF line, no case of UB was observed using UHD mapping, suggesting that the presence of a conduction block along a RF line is always associated with a block in the opposite direction

Distance between the descending aorta and the left inferior pulmonary vein as a determinant of biophysical parameters during paroxysmal atrial fibrillation cryoablation

International audienceINTRODUCTION: The distance from the descending aorta (DA) to the posterior wall of the left atrium (LA) is variable. We aimed to determine whether the proximity between the DA and the left inferior pulmonary vein (LIPV) ostium has an impact on biophysical parameters and cryoballoon (CB) ablation efficacy during LIPV freezing. METHODS: Patients referred for CB-ablation of atrial fibrillation (AF) in two high-volume centers were included. Cryoablation data were collected prospectively for each patient. The anatomical relationships between the LIPV and the DA (distance LIPV ostium-DA, presence of an aortic imprint on the posterior aspect of the LIPV) were then retrospectively analysed on the LA computed tomography (CT) scans realized before AF ablation. RESULTS: 350 patients were included (70% men, 59.7±11.5 yo). The decrease in the Ostium-DA distance was significantly correlated to the increase in the Time-To-Isolation (TTI) (r=-0.31; p=0.036), with less negative temperature (r=-0.11; p=0.045). Similarly, the presence of an aortic imprint on the LIPV was associated with a longer TTI (p<0.001). The analysis of redo procedures data shows a trend toward the presence of shorter ostium-DA distances (15.3±3.29 vs 18.1±4.99, p=0.15) and more frequent aortic imprints (63.6% vs 47.5%, p=0.34) in patients with LIPV reconnection as opposed to patients without reconnection in the LIPV. CONCLUSION: Our findings indicated that the DA seems to have a "radiator" effect influencing LIPV cryoablation parameters during CB-ablation. Additional studies will be needed to elucidate whether this biophysical influence has a clinical impact in LIPVs reconnections. This article is protected by copyright. All rights reserved