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Search Results: 1 - 10 of 10895 matches for " Pierre Bordachar "
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Implantation of an Endovenous Pacemaker in a Patient with Parkinson’s Disease and Bilateral Deep Brain Stimulators
Maxime de Guillebon,Pierre Bordachar,Jacques Clementy
Clinical Medicine : Cardiology , 2007,
Response to Cardiac Resynchronization Therapy: The Muscular Metabolic Pathway
Jérémie Jaussaud,Pierre Blanc,Pierre Bordachar,Raymond Roudaut,Hervé Douard
Cardiology Research and Practice , 2011, DOI: 10.4061/2011/830279
Abstract: Background. Changes in peripheral muscle in heart failure lead to a shift from aerobic to early anaerobic metabolism during exercise leading to ergoreflex overactivation and exaggerated hyperventilation evaluated by the VE/VCO2 slope. Methods. 50 patients (38 males, 59±12 years) performed cardio-pulmonary exercise test with gaz exchange measurement and echocardiographic evaluation before and 6 months after CRT. Results. The peak respiratory exchange (VCO2/ VO2) ratio was significantly reduced from 1.16±0.14 to 1.11±0.07 (<.05) and the time to the anaerobic threshold was increased from 153±82 to 245±140 seconds (=.01). Peak VO2, VE/VCO2, peak circulatory power and NYHA were improved after CRT (13±4 to16±5 ml/kg/min (<.05), 45±16 to 39±13 (<.01), 1805±844 to 2225±1171 mmHg.ml/kg/min (<.01) and 3±0.35 to 1.88±0.4 (=.01)). In addition, left ventricular ejection fraction and end-systolic volumes were improved from 24±8 to 29±7% (<.01) and from 157±69 to 122±55 ml (<.01). Conclusion. We suggest that CRT leads to an increase in oxidative muscular metabolism and postponed anaerobic threshold reducing exaggerated hyperventilation during exercise.
Cardiac Resynchronization Therapy Reduces Metaboreflex Contribution to the Ventilatory Response in Heart Failure Population
Jérémie Jaussaud,Laurie Aimable,Pierre Bordachar,Pierre Dos Santos,Laurent Barandon,Philippe Ritter,Raymond Roudaut,Hervé Douard
Cardiology Research and Practice , 2012, DOI: 10.1155/2012/914071
Abstract: Background. Metaboreflex overactivation has been proprosed to explain exaggerated hyperventilation in heart failure population. We investigated the metaboreflex activation after cardiac resynchronization therapy (CRT). Methods. 10 heart failure patients (mean left ventricular ejection fraction (LVEF) 27±4%) schedulded for CRT implantation were prospectively studied. At baseline and after 6 month follow up two maximal cardiopulmonary exercise tests with and without regional circulatory occlusion (RCO) during recovery were performed. RCO was achieved by inflation of bilateral upper thigh tourniquets 30 mmHg above peak systolic blood pressure during 3 minutes after peak exercise. Metaboreflex contribution to the ventilatory response was assessed as the difference in ventilatory data at the third minute during recovery between the two tests (Δ). Results. Patients had enhanced VE/VCO2 slope (40±9) and an evident metaboreflex contribution to the high ventilatory response (ΔVE: 3±4 L/min; =0.05, ΔRR: 4.5±4/min; =0.003 and ΔVE/VCO2: 5.5±4; =0.007). 6 months after CRT implantation, NYHA class, LVEF, peak VO2 and VE/VCO2 were significantly improved (1.4±0.5; <0.001, 42±7%; <0.001, 16.5±3 mL/kg/min; =0.003; 33±10; =0.01). Metaboreflex contribution to VE, RR, and VE/VCO2 was reduced compared with baseline (=0.08, =0.01 and =0.4 resp.). Conclusion. 6 months after CRT metaboreflex contribution to the ventilatory response is reduced.
Fast Simulation of Mechanical Heterogeneity in the Electrically Asynchronous Heart Using the MultiPatch Module
John Walmsley?,Theo Arts?,Nicolas Derval?,Pierre Bordachar,Hubert Cochet?,Sylvain Ploux?,Frits W. Prinzen?,Tammo Delhaas?,Joost Lumens
PLOS Computational Biology , 2015, DOI: 10.1371/journal.pcbi.1004284
Abstract: Cardiac electrical asynchrony occurs as a result of cardiac pacing or conduction disorders such as left bundle-branch block (LBBB). Electrically asynchronous activation causes myocardial contraction heterogeneity that can be detrimental for cardiac function. Computational models provide a tool for understanding pathological consequences of dyssynchronous contraction. Simulations of mechanical dyssynchrony within the heart are typically performed using the finite element method, whose computational intensity may present an obstacle to clinical deployment of patient-specific models. We present an alternative based on the CircAdapt lumped-parameter model of the heart and circulatory system, called the MultiPatch module. Cardiac walls are subdivided into an arbitrary number of patches of homogeneous tissue. Tissue properties and activation time can differ between patches. All patches within a wall share a common wall tension and curvature. Consequently, spatial location within the wall is not required to calculate deformation in a patch. We test the hypothesis that activation time is more important than tissue location for determining mechanical deformation in asynchronous hearts. We perform simulations representing an experimental study of myocardial deformation induced by ventricular pacing, and a patient with LBBB and heart failure using endocardial recordings of electrical activation, wall volumes, and end-diastolic volumes. Direct comparison between simulated and experimental strain patterns shows both qualitative and quantitative agreement between model fibre strain and experimental circumferential strain in terms of shortening and rebound stretch during ejection. Local myofibre strain in the patient simulation shows qualitative agreement with circumferential strain patterns observed in the patient using tagged MRI. We conclude that the MultiPatch module produces realistic regional deformation patterns in the asynchronous heart and that activation time is more important than tissue location within a wall for determining myocardial deformation. The CircAdapt model is therefore capable of fast and realistic simulations of dyssynchronous myocardial deformation embedded within the closed-loop cardiovascular system.
Atrial Tachycardias Arising from Ablation of Atrial Fibrillation: A Proarrhythmic Bump or an Antiarrhythmic Turn?
Ashok J. Shah,Amir Jadidi,Xingpeng Liu,Shinsuke Miyazaki,Andrei Forclaz,Isabelle Nault,Lena Rivard,Nick Linton,Olivier Xhaet,Nicolas Derval,Frederic Sacher,Pierre Bordachar,Philippe Ritter,Meleze Hocini,Pierre Jais,Michel Haissaguerre
Cardiology Research and Practice , 2010, DOI: 10.4061/2010/950763
Abstract: The occurrence of atrial tachycardias (AT) is a direct function of the volume of atrial tissue ablated in the patients with atrial fibrillation (AF). Thus, the incidence of AT is highest in persistent AF patients undergoing stepwise ablation using the strategic combination of pulmonary vein isolation, electrogram based ablation and left atrial linear ablation. Using deductive mapping strategy, AT can be divided into three clinical categories viz. the macroreentry, the focal and the newly described localized reentry all of which are amenable to catheter ablation with success rate of 95%. Perimitral, roof dependent and cavotricuspid isthmus dependent AT involve large reentrant circuits which can be successfully ablated at the left mitral isthmus, left atrial roof and tricuspid isthmus respectively. Complete bidirectional block across the sites of linear ablation is a necessary endpoint. Focal and localized reentrant AT commonly originate from but are not limited to the septum, posteroinferior left atrium, venous ostia, base of the left atrial appendage and left mitral isthmus and they respond quickly to focal ablation. AT not only represents ablation-induced proarrhythmia but also forms a bridge between AF and sinus rhythm in longstanding AF patients treated successfully with catheter ablation. 1. Introduction Atrial fibrillation (AF) is no longer a formidable rhythm since ablationists challenged this notorious arrhythmia more than a decade ago in their unprecedented quest for sinus rhythm (SR) [1]. Ablation strategies are based on clinical types of AF but nevertheless, the volume of tissue ablated to treat AF is highest for any cardiac arrhythmia described so far. Paroxysmal AF is amenable to catheter ablation with minimum atrial tissue destruction such that electrical isolation of pulmonary veins (PVs) suffices for establishing cure [2]. Persistent and longer lasting forms of AF necessitate extensive atrial tissue ablation in addition to PV isolation to restore SR [3–7]. Besides having evolved as a therapeutic option in symptomatic AF, surgical ablation has become a routine adjunct to many valvular surgeries and may be employed with surgical coronary revascularization and also as a “standalone” procedure [8, 9]. Despite improvements in ablation strategies, relatively high volume of tissue ablation is performed in AF. Together with remodeling of atria, it provides a favourable substrate for the development of sustained atrial tachycardia(s) during and after AF ablation (ATp) [4]. 2. Magnitude of ATp Burden Based on our observation and also that of
Análisis de equivalencia entre cuatro escalas de evaluación funcional del hombro en pacientes operados del manguito de los rotadores y en pacientes con diagnóstico de hombro doloroso: Estudio transversal y observacional
Pati?o,Osvaldo; Beribé,Raúl; Bordachar,Diego; Intelangelo,Leonardo; Araya,Rodrigo;
Revista de la Asociaci?3n Argentina de Ortopedia y Traumatolog?-a , 2011,
Abstract: background: the purpose of our study was to compare the concurrent reliability of 4 commonly used outcome scales for rotator cuff surgery and shoulder pain syndrome. methodology: 16 female and 7 male patients with rotator cuff surgery, and 7 female and 10 male patients with shoulder pain syndrome were analyzed. four professionals blindly applied the following scales: simple shoulder test (sst), constant and murley scale (constant), university of california los angeles shoulder score (ucla) and american shoulder and elbow surgeons shoulder score index (ases). the intraclass correlation coefficient (icc) and 95% confidence interval (ci) and p < 05 significance level were used for statistical purposes. results: the dominant shoulders were affected in 65% of the patients. the icc(ci 95%) between scales was: sst vs constant 0.39 (-15.3; 0.68) .064, vs ases 0.29 (-0.34; 0.62); vs ucla 0.56 (0.17; 0.77). constant vsases 0.834 (0.69; 0.91); vs ucla 0.706 (0.44; 0.85) and ases vs ucla 0.679 (0.39; 0.83). conclusions: our study found no concurrent reliability between sst and c-m, and between sst and ases. reliability was moderate between sst and ucla, between c-m and ucla and between ases and ucla. the highest reliability was observed comparing c-m and ases. we estimate that when using both scales, the results obtained should be similar.
Bending Fuchsian representations of fundamental groups of cusped surfaces in PU(2,1)
Pierre Will
Mathematics , 2011,
Abstract: We describe a family of representations of $\pi_1(\Sigma)$ in PU(2,1), where $\Sigma$ is a hyperbolic Riemann surface with at least one deleted point. This family is obtained by a bending process associated to an ideal triangulation of $\Sigma$. We give an explicit description of this family by describing a coordinates system in the spirit of shear coordinates on the Teichm\"uller space. We identify within this family new examples of discrete, faithful and type-preserving representations of $\pi_1(\Sigma)$. In turn, we obtain a 1-parameter family of embeddings of the Teichm\"uller space of $\Sigma$ in the PU(2,1)-representation variety of $\pi_1(\Sigma)$. These results generalise to arbitrary $\Sigma$ the results obtained in a previous paper for the 1-punctured torus.
Two Generator groups acting on the complex hyperbolic plane
Pierre Will
Mathematics , 2015,
Abstract: This is an expository article about groups generated by two isometries of the complex hyperbolic plane.
How to Introduce the Cyclic Group and Its Properties Representation with Matlab ? Thanks to Magic Using the Perfect Faro Shuffle  [PDF]
Pierre Schott
Creative Education (CE) , 2011, DOI: 10.4236/ce.2011.21005
Abstract: Why use Magic for teaching arithmetic and geometric suit, additive groups, and algorithmic notions through Matlab? Magicians know that, once the surprise has worn off, the audience will seek to understand how the trick works. The aim of every teacher is to interest their students, and a magic trick will lead them to ask how? And why? And how can I create one myself? In this article we consider a project I presented in 2009. I summarize the project scope, the students' theoretical studies, their approach to this problem and their computer realizations. I conclude using the mathematical complement as well as weak and strong points of this approach. Whatever the student's professional ambitions, they will be able to see the impact that originality and creativity have when combined with an interest in one's work. The students know how to “perform” a magic trick for their family and friends, a trick that they will be able to explain and so enjoy a certain amount of success. Sharing a mathematical / informatics demonstration is not easy and that they do so means that they will have worked on understood and are capable of explaining this knowledge. Isn't this the aim of all teaching?
Pedestrian Analysis of Harmonic Plane Wave Propagation in 1D-Periodic Media  [PDF]
Pierre Hillion
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.24027
Abstract: The propagation of TE, TM harmonic plane waves impinging on a periodic multilayer film made of a stack of slabs with the same thickness but with alternate constant permittivity is analyzed. To tackle this problem, the same analysis is first performed on only one slab for harmonic plane waves, solutions of the wave equa- tion. The results obtained in this case are generalized to the stack, taking into account the boundary condi- tions generated at both ends of each slab by the jumps of permittivity. Differential electromagnetic forms are used to get the solutions of Maxwell’s equations.
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