Добірка наукової літератури з теми "Flux coronaire"

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Статті в журналах з теми "Flux coronaire":

1

Meimoun, P., S. Sayah, B. Maitre, A. L. Bore, T. Benali, M. Beausoleil, and J. Bailly. "Mesure du flux et de la réserve coronaire par échographie transthoracique : un vieux concept, un outil moderne, des intérêts multiples." Annales de Cardiologie et d'Angéiologie 53, no. 6 (November 2004): 325–34. http://dx.doi.org/10.1016/j.ancard.2004.09.009.

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2

Pinaquy, J. B., P. Ferenczi, F. Debordeaux, L. Bordenave, H. Douard, T. Couffinhal, and Y. Pucheu. "Corrélation entre les flux myocardiques, la réserve coronaire et les scores de risque cardiovasculaire Framingham et ESC-SCORE(+ Running poster)." Médecine Nucléaire 45, no. 4 (July 2021): 203. http://dx.doi.org/10.1016/j.mednuc.2021.06.056.

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Bailly, M., F. Thibault, M. Courtehoux, G. Metrard, and M. J. Santiago Ribeiro. "Effet de la correction d’atténuation sur le calcul des flux et de la réserve coronaire en scintigraphie myocardique sur caméra CZT." Médecine Nucléaire 44, no. 2 (March 2020): 101–2. http://dx.doi.org/10.1016/j.mednuc.2020.01.118.

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4

Huang, Qiaobing, Mac Wu, Cynthia Meininger, Katherine Kelly, and Yuan Yuan. "Neutrophil-dependent augmentation of PAF-induced vasoconstriction and albumin flux in coronary arterioles." American Journal of Physiology-Heart and Circulatory Physiology 275, no. 4 (October 1, 1998): H1138—H1147. http://dx.doi.org/10.1152/ajpheart.1998.275.4.h1138.

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Platelet-activating factor (PAF) has been implicated in the pathogenesis of ischemic heart disease, reperfusion injury, and inflammatory reactions. Although neutrophils have been shown to primarily mediate PAF-induced microvascular dysfunction, the vasoactive effect of PAF and its neutrophil-dependent mechanism have not been directly and systematically studied in coronary resistance vessels. Therefore, the aim of this study was to examine the effects of PAF on coronary arteriolar function and neutrophil dynamics using an isolated and perfused microvessel preparation. Topical application of PAF to the vessels induced a dose-dependent decrease in the diameter but an increase in the apparent permeability coefficient of albumin. Disruption of the endothelium abolished the vasomotor response to PAF, and perfusion of neutrophils significantly augmented PAF-induced changes in vasomotor tone and permeability. Furthermore, the interaction between neutrophils and the endothelium was studied in the intact perfused coronary arterioles. Under control conditions, there were no adherent neutrophils observed in the vessels at varied intraluminal flow velocities. However, administration of PAF caused neutrophil adhesion to the endothelium of coronary arterioles at low flow velocities. Western blot analysis indicated that PAF upregulated the expression of intercellular adhesion molecule-1 in cultured coronary microvascular endothelial cells. Taken together, the results suggest that 1) PAF induces vasoconstriction and hyperpermeability in coronary arterioles via an endothelium-dependent and neutrophil-mediated mechanism, and 2) PAF is able to stimulate neutrophil adhesion in coronary arterioles under a condition of low flow rate.
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ROGERS, S., A. KHALATBARI, B. DATTA, S. ELLERY, V. PAUL, M. FRENNEAUX, and P. JAMES. "NO metabolite flux across the human coronary circulation." Cardiovascular Research 75, no. 2 (July 15, 2007): 434–41. http://dx.doi.org/10.1016/j.cardiores.2007.04.019.

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6

SYRRIS, Petros, Nicholas D. CARTER, James C. METCALFE, Paul R. KEMP, David J. GRAINGER, Juan C. KASKI, David C. CROSSMAN та ін. "Transforming growth factor-β1 gene polymorphisms and coronary artery disease". Clinical Science 95, № 6 (1 грудня 1998): 659–67. http://dx.doi.org/10.1042/cs0950659.

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1. A meta-analysis of 17 years of literature on erythrocyte Na+/Li+ countertransport (NLCT) and Na+/K+ co-transport (COT) measurements in relation to essential hypertension is presented. The analysis aimed to answer two questions: (i) Which clinical or laboratory variables influence NLCT and COT flux values? (ii) How useful are NLCT and COT measurements as a diagnostic aid in essential hypertension? 2. Regression analysis was performed on the mean flux values and relevant clinical and laboratory values. Studies in both normotensive and hypertensive subjects were stratified for variables which showed a significant association with the measured flux. For hypertensive subjects the studies were also stratified for medication. Means of strata were calculated after weighing the mean of a study by the inverse of its own variance and were compared in normotensive as well as hypertensive subjects using a t-test. 3. The analysis did not demonstrate systematic effects of laboratory variables for either NLCT or COT. It was found that essential hypertension, family history of hypertension, gender and antihypertensive medication are main determinants for the flux values of both transport systems. After stratification for these determinants, significant differences in weighed mean flux values between normotensive and hypertensive subjects were demonstrated. However, these differences are much smaller than the variance in the weighed mean flux values, suggesting the existence of other unknown variables that strongly affect the flux rates. 4. In conclusion, NLCT and COT measurements cannot be of diagnostic use in essential hypertension.
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Jardine, Moira M. "Topology of stellar coronae." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 289–90. http://dx.doi.org/10.1017/s1743921307010642.

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AbstractWhile the existence of cycles in stellar chromospheric flux has been known for some time, the nature of the corresponding coronal response has been more elusive. We describe recent results on the relationship between cyclic variations in surface magnetic flux and coronal structure and re-assess the role of prominence observations in understanding the topology of stellar coronas. We present a new paradigm for prominence support which allows for extended prominences to co-exist with a compact corona. We discuss briefly the recent results on coronal structure in high- and low-mass stars and their implications for dynamo theory.
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Schrijver, Carolus J., and Alan M. Title. "The Heating of Cool‐Star Coronae: From Individual Loops to Global Flux‐Flux Scalings." Astrophysical Journal 619, no. 2 (February 2005): 1077–83. http://dx.doi.org/10.1086/426709.

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Noll, T., A. Hempel, and H. M. Piper. "Neuropeptide Y reduces macromolecule permeability of coronary endothelial monolayers." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 5 (November 1, 1996): H1878—H1883. http://dx.doi.org/10.1152/ajpheart.1996.271.5.h1878.

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The effect of neuropeptide Y (NPY) on cellular adenosine 3',5'-cyclic monophosphate (cAMP) contents and macromolecule permeability was studied in cultured monolayers of microvascular coronary endothelial cells from rat. Macromolecule permeability was continuously determined as passage of albumin across the monolayers. NPY (10(-10)-10(-7) M) decreased albumin flux and cellular cAMP content in a dose-dependent manner, with a half-maximal effect on albumin flux at 1.4 x 10(-9) M and on cAMP contents at 0.7 x 10(-9) M. A maximum effect of NPY was observed at 10(-7) M, decreasing albumin flux by 71 +/- 8% and cellular cAMP contents by 80 +/- 9% (mean +/- SD, n = 6, P < 0.05) compared with control. The effect of NPY on albumin flux was not altered in the presence of 10(-5) M indomethacin (an inhibitor of cyclooxygenase) and 10(-5) M NG-nitro-L-arginine (an inhibitor of nitric oxide synthase). NPY (10(-7) M) also antagonized the increase of albumin flux and cAMP content induced by 10(-6) M isoproterenol. Pretreatment of endothelial monolayers with pertussis toxin (1 microgram/ml for 2 h) abolished the effect of NPY on albumin flux and cAMP contents. This study shows that NPY can modulate macromolecule permeability of endothelial monolayers by reducing the cellular cAMP contents. Together with the effect of pertussis toxin, the data suggest that NPY exerts its antiadrenergic effect on cAMP metabolism and endothelial barrier function by receptors linked to adenylyl cyclase via an inhibitory guanosine-binding protein in coronary endothelial cells.
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Honig, C. R., J. L. Frierson, and T. E. Gayeski. "Anatomical determinants of O2 flux density at coronary capillaries." American Journal of Physiology-Heart and Circulatory Physiology 256, no. 2 (February 1, 1989): H375—H382. http://dx.doi.org/10.1152/ajpheart.1989.256.2.h375.

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Calculations indicate that the PO2 in plasma falls to zero approximately 3 microns from an erythrocyte at O2 consumption (VO2) characteristic of myocardium (Federspiel, W.A., and A. Popel, Microvasc. Res. 32: 164-189, 1986). We measured distances between individual red cells along capillaries in rat hearts rapidly frozen in situ. Cell spacing varied widely even in branches of the same capillary. Plasma gaps between red cells were divided into two populations, those less than 5 microns and those greater than 5 microns. Mean gap lengths were 2.1 and 16.5 microns, respectively. Although the number of long plasma gaps was underestimated, gaps greater than 5 microns accounted for one-third of observed capillary length. Frozen muscles were also viewed in cross section. Because the depth of penetration of light was approximately equal to 3 microns, counts of red cell-containing capillary profiles in cross section depend on cell spacing as well as on number of cell-containing flow paths. Counts varied markedly with arterial O2 partial pressure, indicating that the capillary surface area functional for O2 transport changes in response to stress. The adaptive role of change in O2 flux density (flux per area) is discussed in light of new knowledge of tissue O2 gradients.

Дисертації з теми "Flux coronaire":

1

Adjedj, Julien. "Circulation coronaire : Principes et méthodes de mesure invasive du flux coronaire segmentaire en pratique clinique." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC0006/document.

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La circulation artérielle coronaire est un système complexe dont les méthodes de mesures invasivespermettent une évaluation en pratique clinique.Matériels et méthodes Nous développons, dans deux revues, les principes et méthodes des différentes techniques invasivesde mesure du flux coronaire en pratique clinique. Puis nous étudions l’impact clinique de l’utilisationde la Fractional Flow Reserve (FFR) dans l’évaluation des sténoses coronaires intermédiaires, lesmoyens pharmacologiques pour mesurer la FFR et sa corrélation avec l’évaluation angiographique enfonction des facteurs de risque cardiovasculaires. Enfin, nous décrivons les principes et méthodesd’une technique de mesure du flux coronaire segmentaire permettant d’obtenir la FFR, le flux et lesrésistances absolues avec un microcathéter de perfusion qui, sur un principe de thermodilutionpermet d’évaluer distinctement la macro et la microcirculation coronaire.Résultats Nous recommandons une valeur seuil de FFR de 0,80 pour guider la revascularisation car le nombred’événements cardiovasculaires et la mortalité sont spontanément supérieurs chez les patients avecune FFR <0,80 comparativement à une FFR ≥0,80 (9,4 vs. 4,8%, P=0,06 et 7,5 vs. 3,2%, P=0,06;respectivement). Nous avons étudié différents agents hyperémiants permettant de mesurer la FFR:l’adénosine (100 μg à 200 μg) permettant d’obtenir une hyperémie maximale, et le produit decontraste permettant d’atteindre 65% de cette hyperémie maximale. La mesure de la FFR avec duproduit de contraste permet de meilleures performances diagnostiques que les indices de reposcomparé à la FFR sous adénosine. Nous avons établi que la corrélation entre la FFR et le degré desténose angiographique est faible et inversement proportionnel au nombre de facteurs de risquecardiovasculaires, particulièrement chez les patients diabétiques. Enfin, nous avons décrit dans troisétudes, le principe de thermodilution coronaire et la méthode de mesures du flux coronaire et desrésistances microvasculaires avec un microcathéter de perfusion intracoronaire spécifique. Nousavons montré que cette technique est précise (R=0,98), qu’elle induit une hyperémie maximale etlocale sans agent hyperémiant et quelle est reproductible chez l’homme (R=0,91).Conclusion La compréhension de la circulation coronaire et l’application chez l’homme des techniques demesure du flux coronaire segmentaire sont essentielles tant en pratique clinique courante qu’enrecherche
Coronary circulation is complex and highly regulated while invasive coronary flow measurements techniques allow the assessment of coronary physiology in clinical practice. Material et methods We describe in two reviews the principles and methods of different invasive coronary flowmeasurements techniques in clinical practice. We study the clinical impact of fractional flow reserve(FFR) in intermediate coronary stenosis, the hyperemic agents and dosage to measure FFR and FFRcorrelation with angiographic indices according to risk factors accumulation. Finally, we describe the principle and method of coronary flow and microvascular resistances measurements with a dedicated infusion microcatheter for coronary thermodilution to obtain assessment of macro and microvascular components of coronary circulation. Results We recommend the FFR cut off value of 0.80 to guide revascularization based on our study showing higher myocardial infarction and death rate in patients treated with medical therapy and FFR<0.80compared to those with FFR>0.80, respectively 9.4 versus 4.8%, P=0.06 and 7,5 versus 3,2%, P=0.06. We studied different hyperemic agents and dosages and showed that intracoronary adenosine at 100μg to 200 μg induce maximal hyperemia while contrast medium induce 65% of maximal hyperemia. Therefore, FFR measurements with contrast medium is feasible and has better accuracy than restindices compared to FFR. We establish the weak correlation between FFR and angiographic indicesand weakens correlation as risk factors accumulates, especially in diabetic patients. Finally, we described in three studies the method of absolute coronary flow and microvascular resistancesmeasurements based on thermodilution principle with a dedicated infusion catheter. We showed anaccurate measurement with this technique (R=0.98), which induces maximal hyperemia without theneed of hyperemic agent with reproducible measurements in humans (R=0,91).Conclusion The use of invasive coronary flow measurements to study the coronary circulation is essential inclinical practice and in research
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Taurel, Marianne. "Evaluation de la réserve coronaire et/ou de la fonction endothéliale dans l'insuffisance cardiaque et l'athérosclérose expérimentales : effets des inhibiteurs du système rénine-angiotensine." Paris 11, 2001. http://www.theses.fr/2001PA11T021.

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Contexte : L'inhibition du système rénine-angiotensine (SRA) s'est avérée efficace dans la prévention et le traitement d'un certain nombre de maladies cardiovasculaires chroniques, comme l'hypertension artérielle, l'insuffisance cardiaque et plus récemment l'athérosclérose. Nombre de mécanismes (cardiaques, hémodynamiques, structuraux. . . ) impliqués dans les effets favorables des inhibiteurs du SRA ont été explorés. Il apparaît que les inhibiteurs du SRA sont, notamment capables de limiter le développement des altérations structurales et/ou fonctionnelles vasculaires qui accompagnent à des degrés divers et en des localisations variables (cérébrale, coronaire et rénale) ces pathologies. Objectifs : Nos objectifs ont été : (1) de caractériser dans le modèle d'insuffisance cardiaque post­ischémique chez le rat, la dysfonction coronaire évaluée in vivo par la mesure de la réserve de dilatation coronaire (technique des fluosphères) et ex vivo par l'étude de la réactivité vasculaire coronaire (technique du myographe) à deux stades du développement de la maladie, l'un précoce (6 semaines post-infarctus) et l'autre tardif (6 mois post-infarctus), (2) d'explorer dans un modèle de maladie athéromateuse chez la souris déficiente en ApoE (ApoE-/-), les altérations fonctionnelles vasculaires au niveau de différentes artères (aorte et carotide), et enfin (3) de déterminer les effets de l'inhibition pharmacologique du SRA sur l'apparition de ces altérations afin d'évaluer l'impact vasculaire de ces substances dans l'insuffisance cardiaque et l'athérosclérose. Résultats : Parallèlement à l'altération de la fonction cardiaque et au remodelage cardiaque, l'insuffisance cardiaque post-ischémique du rat s'accompagne (1) d'une réduction précoce de la réserve coronaire ventriculaire gauche et droite, qui s'aggrave avec l'évolution de la maladie et (2) d'une diminution de la relaxation endothélium-dépendante des artères coronaires qui n'apparaît qu'au seul stade tardif de la maladie. Chez les rats insuffisants cardiaques, le blocage du SRA n'a induit aucune amélioration ni précoce ni tardive de la réserve coronaire ventriculaire gauche mais a restauré la réserve coronaire ventriculaire droite et normalisé la fonction endothéliale des artères coronaires. Les souris ApoE-I- âgées de 30 semaines présentent une hypercholestérolémie et une athérosclérose sévère qui s'accentuent lorsque ces animaux sont nourris en régime gras. Cependant, aucune modification des réponses vasculaires contractiles ou relaxantes n'a été observée chez les souris comparativement aux souris sauvages. Néanmoins, bien que dans les conditions basales, les réponses relaxantes à l'acétylcholine soient parfaitement superposables entre les deux souches, les mêmes mécanismes responsables de cette relaxation, notamment au niveau de la carotide, sont différents en régime gras. En effet, alors que les relaxations carotidiennes médiées par l'acétylcholine impliquent exclusivement la voie du NO chez les animaux sauvages, elles impliquent chez les souris ApoE-/- à la fois la voie du NO et celle des prostaglandines. Ainsi, dans un contexte d'hypercholestérolémie sévère, un défaut de production et/ou de libération du NO endothélial par les carotides de souris ApoE-/- est immédiatement compensé par un relais par la cyclooxygénase. L'inhibition du SRA limite le développement des lésions athéromateuses indépendamment d'une réduction des taux plasmatiques du cholestérol et améliore la participation du NO à la relaxation endothélium-dépendante des carotides de souris ApoE-/- Conclusions : Nos résultats montrent que l'inhibition du SRA exerce des effets bénéfiques vasculaires tant dans l'insuffisance cardiaque que dans l'athérosclérose expérimentales, ces derniers contribuant à leur effet thérapeutique au long cours dans ces pathologies.
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Lethimonnier, Franck. "Evaluation des cardiopathies ischémiques par IRM quantification du flux et de la réserve coronaire : visualisation des sténoses par angiographie 3D : étude du retentissement fonctionnel par analyse de la fonction ventriculaire gauche." Angers, 1999. http://www.theses.fr/1999ANGE0508.

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Rasser, Charlotte. "Biocompatibility improvement conferred by the immobilization of a CD31 peptide on endovascular stents." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC317/document.

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Au cours des dernières décennies, les stents coronaires et les stents déviateurs de flux intracrâniens ont révolutionné le traitement endovasculaire de deux pathologies artérielles différentes : la maladie coronarienne et les anévrismes intracrâniens. Ces deux types d’endoprothèses métalliques ont des mécanismes de fonctionnement différents, mais ils sont tous deux associés à des complications qui découlent de problèmes de biocompatibilité. En particulier, la couverture rapide de ces endoprothèses par des cellules endothéliales présentant un phénotype anti-inflammatoire et anti-thrombotique est cruciale pour leur intégration à l’interface vaisseau/sang. Par conséquent, le développement de solutions visant à améliorer l’endothélialisation et l’intégration de ces deux types de stents dans la paroi vasculaire représenterait un progrès majeur dans leur domaine respectif.Dans ce contexte, cette thèse porte sur l’immobilisation d’une molécule bioactive à la surface de stents coronaires et de stents déviateurs de flux, afin de résoudre leurs problèmes de biocompatibilité. La molécule bioactive utilisée est un peptide synthétique, appelé P8RI, qui promeut les fonctions régulatrices de la glycoprotéine transmembranaire CD31 : l’inhibition de l’activation des plaquettes et des leucocytes, ainsi que l’amélioration de la survie, de la migration et de la fonction de barrière des cellules endothéliales.La première partie de ce travail de thèse a consisté à développer un procédé d’immobilisation du P8RI sur des stents métalliques. Nous avons successivement adopté trois approches : l’immobilisation directe du peptide sur des surfaces d’alliage fonctionnalisées par plasma ; le dépôt chimique en phase vapeur assisté par plasma d’une couche intermédiaire de polymère ; et le dépôt d’une couche de polydopamine par auto-polymérisation, suivi de l’immobilisation d’un bras d’ancrage et de la liaison du P8RI par chimie click sans cuivre.Nous avons ensuite réalisé une évaluation in vitro de la biocompatibilité des surfaces d’alliage ainsi revêtues, en termes de propriétés anti-thrombotiques, anti-inflammatoires et pro-endothélialisation. Les surfaces sur lesquelles le P8RI avait été immobilisé ont montré une tendance à diminuer l’adhésion plaquettaire, à améliorer l’adhérence et la fonction de barrière de cellules endothéliales vasculaires humaines, et à promouvoir un phénotype anti-inflammatoire et anti-thrombotique chez ces dernières. Enfin, nous avons évalué in vivo des stents coronaires et déviateurs de flux recouverts de P8RI. Les stents coronaires ont été implantés dans des artères coronaires de porcs, et les résultats préliminaires ont montré une endothélialisation plus complète et une moindre densité de leucocytes adhérents sur les stents recouverts de P8RI que sur les témoins. Quant aux stents déviateurs de flux recouverts de P8RI, implantés dans un modèle d’anévrisme carotidien induit par incubation d'élastase chez le lapin, ils ont été associés à la formation d’une néointima plus épaisse et mieux organisée que sur les témoins, en particulier au niveau du collet anévrismal, ce qui implique de moindres risques de persistance du flux sanguin et de rupture d’anévrisme
Over the last decades, coronary stents and intracranial flow diverting stents have revolutionized the endovascular treatment of two different arterial pathologies: coronary artery disease and intracranial aneurysms. The working mechanisms of these metallic endoprostheses are different but both are associated with complications stemming from biocompatibility issues. In particular, the rapid covering by endothelial cells presenting an anti-inflammatory and anti-thrombotic phenotype is key to the integration of the endoprosthesis at the blood/vessel interface. Thus, the development of solutions to improve the endothelialization and the integration of these two types of stents in the vessel wall would represent a major progress in their respective field.In this context, this thesis work deals with the immobilization of a bioactive molecule on coronary stents and flow diverting stents in order to solve their biocompatibility issues. The bioactive molecule that we used is a synthetic peptide, named P8RI, which promotes the regulatory functions of the transmembrane glycoprotein CD31 : the inhibition of platelets and leukocytes activation, as well as the enhancement of endothelial cell survival, migration and barrier function.The first part of this thesis work consisted in the development of a process for the immobilization of P8RI on metallic stents. We adopted three successive approaches: the direct immobilization of the peptide on plasma-functionalized alloy surfaces; the plasma-enhanced chemical vapor deposition of an intermediate polymeric layer; and the deposition of a polydopamine coating by self-polymerization, followed with the immobilization of a linker and the binding of P8RI by copper-free click chemistry.We then carried out an in vitro evaluation of the biocompatibility of the resulting coated alloy surfaces, in terms of anti-thrombotic, anti-inflammatory, and pro-endothelialization properties. The surfaces on which P8RI had been immobilized were shown to exhibit a tendency to decrease platelet adhesion, increase endothelial cell adhesion and barrier function, and promote an anti-inflammatory and anti-thrombotic phenotype in human vascular endothelial cells.Finally, coronary stents and flow diverting stents were evaluated in vivo. Coronary stents were implanted in the coronary arteries of farm pigs, and preliminary results showed a more complete endothelialization and a lesser density of adherent leukocytes on ‘P8RI-coated’ stents than on the controls. ‘P8RI-coated’ flow diverting stents were implanted in a rabbit elastase-induced carotid aneurysm model. Compared with the controls, they were associated with the formation of a thicker and better organized neointima, in particular on the stent struts in front of the aneurysm neck, which implies lesser risks of persistence of blood flow and aneurysm rupture
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Gibb, Gordon P. S. "The formation and eruption of magnetic flux ropes in solar and stellar coronae." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7069.

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Flux ropes are magnetic structures commonly found in the solar corona. They are thought to play an important role in solar flares and coronal mass ejections. Understanding their formation and eruption is of paramount importance for our understanding of space weather. In this thesis the magnetofrictional method is applied to simulate the formation of flux ropes and track their evolution up to eruption both in solar and stellar coronae. Initially, the coronal magnetic field of a solar active region is simulated using observed magnetograms to drive the coronal evolution. From the sequence of magnetograms the formation of a flux rope is simulated, and compared with coronal observations. Secondly a procedure to produce proxy SOLIS synoptic magnetograms from SDO/HMI and SOHO/MDI magnetograms is presented. This procedure allows SOLIS-like synoptic magnetograms to be produced during times when SOLIS magnetograms are not available. Thirdly, a series of scaling laws for the formation and life-times of flux ropes in stellar coronae are determined as a function of stellar differential rotation and surface diffusion. These scaling laws can be used to infer the response of stellar coronae to the transport of magnetic fields at their surface. Finally, global long-term simulations of stellar corona are carried out to determine the coronal response to flux emergence and differential rotation. A bipole emergence model is developed and is used in conjunction with a surface flux transport model in order to drive the global coronal evolution. These global simulations allow the flux, energy and flux rope distributions to be studied as a function of a star's differential rotation and flux emergence rate.
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Abdalla, Luiz Antonio 1953. "Efeitos da vitamina E sobre o fluxo coronario endotelio-dependente em cães hipercolesterolemicos." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313462.

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Orientador : Paulo Afonso Ribeiro Jorge
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: Foram estudados os efeitos da vitamina E sobre o fluxo coronário endotélio-dependente em cães hipercolesterolêmicos. A pesquisa foi realizada em 21 cães machos adultos, pesando em média 7,4±1,0 kg, que foram divididos em três grupos: controle, hipercolesterolêmico e vitamina E. Os animais do grupo hipercolesterolêmico foram alimentados com uma dieta rica em colesterol (5% g/g) e óleo de coco (10% g/g) por 40 dias. O grupo vitamina E recebeu a mesma dieta, acrescida de 400 Ui de vitamina E, durante os últimos 15 dias do experimento. Os níveis de colesterol total sérico foram avaliados no começo e no final do estudo, por meio de "kits" enzimáticos e espectrofotômetro Beckman 700. O fluxo coronário foi medido por um fluxômetro eletromagnético (Caroline Instruments, Inc.), usando-se um probe, posicionado na artéria coronária descendente anterior esquerda, próximo ao óstio. Uma agulha, conectada a uma bomba de infusão, foi introduzida na artéria coronária para administração de acetilcolina (ACH) e nitroprussiato de sódio (NPS), à velocidade de 5 mg/kg/min. A aorta foi canulada para medida da pressão arterial por intermédio de transdutor acoplado a polígrafo da marca Siemmens (Mingograph 804). Os teores de colesterol e malonodialdeído (MOA) foram, também, medidos em segmentos de vaso coronário.Após 40 dias, os níveis de colesterol sérico haviam aumentado em 203%, no grupo hipercolesterolêmico e, em 198%, no grupo da vitamina E. Entretanto, esta diferença não foi significante (P>0,05). A pressão sangüínea na aorta e a freqüência cardíaca permaneceram sem alteração, durante a administração de ACH. Contudo, a pressão sistólica e a diastólica diminuíram e a freqüência cardíaca aumentou durante a infusão de NPS.O teor de colesterol tecidual e MOA aumentaram, significativamente, (P<0,05) nas amostras de artéria coronária do grupo hipercolesterolêmico, comparativamente aos animais do grupo-controle. A vitamina E reduziu o colesterol tecidual e o MDA nos animais hipercolesterolêmicos (P<0,05).A elevação do percentual do fluxo coronário, durante a administração da ACH, foi significativamente menor no grupo hipercolesterolêmico, quando comparada com an1ma1_ do grupo-controle (P0,05). O fluxo coronário aumentou, durante a administração de NPS, no grupo da vitamina E (P<0,05).Concluiu-se que a hipercolesterolemia reduziu o fluxo coronário endotéliodependente e aumentou o teor de colesterol tecidual e de MDA nas artérias coronárias. A vitamina E reduziu o MDA e o teor de colesterol tecidual, sem afetar significativamente o solúvel de colesterol sérico. A vitamina E restaurou o fluxo coronário, revertendo a disfunção endotelial na hipercolesterolemia
Abstract: The effects of vitamin E on endothelium-dependent coronary flow were studied in hypercholesterolernic dogs. Adult mongrel dogs weighing 7.4±1.0 kg were divided into control, hypercholesterolernic and vitamin E groups. The animals in the hypercholesterolernic group were fed a diet enriched with cholesterol (5%w/w) and coconut oil (l0%w/w) for 40 days. The vitamin E group received the same diet plus 400 IU of vitamin E during the last 15 days of the experiment. Total serum cholesterol levels were evaluated at the beginning and at the end of the experiment using a commercial enzyme kit and a Beckman analyzer. The coronary flow was determined byelectromagnetic flowmetry using a probe positioned in the left anterior descending coronary artery, near the ostium. A needle connected to a perfusion pump was introduced into the coronary artery for the administration of acetycholine and sodium nitroprusside at a rate of 5 ug!kg per min. The aorta was cannulated for the measurement of arterial blood pressure via a pressure transducer coupled to a Siemens multi-channel recorder. The tissue cholesterol content and malonic dialdehyde (MDA) were also measured in isolated coronary vessel specimens. At the end of 40 days, the serum cholesterol levels had increased by 203% and 198% in the hypercholesterolernic and vitamin E groups, respectively. However, the difference in the levels of these two groups was not significant (P>0.05). The aortic blood pressure and heart rate remained inchanged during acetylcholine administration. In contrast, systolic and diastolic pressure fell and the heart rate increased during the infusion of sodium nitroprusside. The tissue cholesterol content and MDA were significantly (P<0.05) increased in coronary artery specimens from the hypercholesterolernic compared to control animals. Vitamin E was able to reduce these increases in cholesterol treated animals (P<0.O5). The percent change in coronary flow during acetylcholine administration was significantly lower in the hypercholesterolernic group when compared with control animals (P<0.05) but was unaltered in the vitamin E group (P>0.05). During sodium nitroprusside administration, the coronary flow increased in the vitamin E group (PDoutorado
Medicina Interna
Doutor em Ciências Médicas
7

Melis, Riera Gaspar. "Papel de la disfunción endotelial en la respuesta a la cocaína del flujo coronario y la contractilidad miocárdica." Doctoral thesis, Universitat de Barcelona, 2003. http://hdl.handle.net/10803/2174.

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1. HIPÓTESIS Y OBJETIVOS

Nuestra hipótesis es que la cocaína causa una depresión de la función ventricular independiente de su efecto sobre el flujo coronario y que esta depresión se agrava en presencia de disfunción endotelial. Analizamos los efectos de la administración sistémica de cocaína sobre el flujo coronario y la función ventricular en un modelo experimental porcino, y si la inhibición de la síntesis de óxido nítrico mediante L-NAME intracoronaria modifica la acción de la cocaína sobre la función ventricular.

2. METODOLOGIA

Se utilizaron 57 animales, en un modelo experimental con anestesia general y con un protocolo quirúrgico que permite analizar las siguientes variables:

a)Parámetros hemodinámicos: Tensión arterial, frecuencia cardíaca, doble producto y presión telediastólica del ventrículo izquierdo.

b)Fracción de acortamiento de la fibra miocárdica

c)Flujo coronario y resistencias coronarias

d)Parámetros adicionales: dP/dt del ventrículo izquierdo, gasto cardíaco y resistencias vasculares sistémicas.
Los animales se aleatorizarón en seis grupos.
Grupo control: salino i.v. (n=5). Grupo 1: cocaína i.v. 10 mg kg -1 durante 20 min. (n=17); Grupo 2: la misma dosis de cocaina después de una infusión intracoronaria de L-NAME 20 mg/kg min -1 (n=16); grupo 3:la misma dosis de cocaína administrada después de la reducción mecánica del 20% del flujo coronario de la arteria descendente anterior mediante una oclusión mecánica externa (n=9); grupo 4: la misma dosis de cocaína después de la administración simultanea de L-arginina y L-NAME intracoronaria (n=5); grupo 5: la misma dosis de cocaína administrada después de la administración simultanea de L-NAME y nitroglicerina intracoronaria ( n=5).

3. RESULTADOS

La cocaína no altero el flujo coronario, mientras que indujo una reducción significativa del gasto cardíaco, de la dp/dt del ventrículo izquierdo y de la fracción de acortamiento. Cuando se administró la cocaína después de la infusión i.c. de L-NAME durante 30 min se produjo una mayor reducción de la fracción de acortamiento, este efecto se abolió con la administración simultanea al L-NAME de L-arginina y nitroglicerina. Los resultados de la administración de cocaína después de la reducción mecánica del 20% del flujo coronario no difieren de los producidos con cocaína sola.

4. CONCLUSIÓN

La cocaína produce una depresión directa de la contractilidad miocárdica. Al inhibir la síntesis de óxido nítrico con L-NAME se produce una vasoconstricción de la microcirculación coronaria que aumenta el efecto depresor de la cocaína sobre el miocardio.
"Role of endotelial dysfuntion on cocaine effects in coronary flow and myocardial contractility "

1. Hypothesis
Cocaine has been associated with myocardial ischaemia and left ventricular dysfunction. Whether nitric oxide (NO) inhibition may potentiate the effects of cocaine on coronary circulation and ventricular function is still unknown.

2.Material and methods

In order to test this hipótesis, 57 pentobarbital-anaesthetized pigs were instrumenteted for systolic blood pressure, coronary blood flow, left ventricular dp/dt, cardiac output, left ventricular end-diastolic and end-systolic leghts and shortening fraction.
The pigs were randomized into six groups: control group: i.v. saline(n=5); group 1: cocaine, 10 mg kg-1 over 20 min (n=17); group 2 : the same dosis of cocaine 30 min after i.c. L-NAME 20 mg/kg min-1 infusion( n=16); group 3: The same dosis of cocaine after the proximal left anterior descending (LAD) flow was reduced to around 20% of the basl value by means of a mechanical occluder (n=9); group 4: the same dosis of cocaine after i.c. simultaneously L-arginina and L-NAME infusion (n=5); group 5: the same dosis of cocaine after simultaneously i.c. L-NAME and nitroglicerine infusion.

3.Results

Cocaine i.v. did not change the coronary blood flow, while it induced a significant reduction in cardiac output, left ventricular dp/dt and shortening fraction. When cocaine was administered after L-NAME infused i.c. a significant more severe reduction of the shortening fraction was induced; this effect was abolished by simultaneosus perfusion of L-arginine and NAG i.c.. The results when cocaine was administered after 20% LAD flow reduction by mechanical occluder did not differ from those of cocaine alone.

4.Conclusions

NO inhibition intesifies the cocaine-induced left ventricular funtion.
8

Sant'Anna, Fernando Mendes. "Influência da avaliação rotineira do fluxo fracionado de reserva durante intervenções coronárias percutâneas na estratégia terapêutica." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-06092006-192836/.

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FUNDAMENTOS: Na prática clínica uma questão importante no manuseio da doença aterosclerótica coronária (DAC) é definir quais lesões estão associadas com isquemia coronária e que devem ser tratadas. Por outro lado, o valor da medida do fluxo fracionado de reserva do miocárdio (FFR) na avaliação da DAC está muito bem estabelecido. O FFR é capaz de definir as lesões que realmente merecem tratamento. No entanto, algumas vezes, a seleção das lesões que devem ser tratadas é feita baseada em critérios angiográficos. O principal objetivo desse estudo é avaliar a percentagem de mudança na estratégia terapêutica inicialmente planejada, após a medida do FFR, em todas as intervenções percutâneas (ICP) eletivas realizadas em nosso Serviço durante um período contínuo de tempo. MÉTODOS: Todos os pacientes agendados para ICP eletivas de Outubro de 2004 a Abril de 2005 foram incluídos no estudo exceto aqueles com oclusão crônica. Duzentos e cinqüenta pacientes e 471 vasos com pelo menos uma lesão ≥ 50% pela estimativa visual com indicação de implante de stent foram avaliados medindo-se o FFR. Antes da PCI 3 cardiologistas reviam o angiograma e classificavam as lesões em 2 categorias, lesões que deveriam ser tratadas e lesões que não deveriam ser. Após a medida do FFR a decisão sobre o tratamento da estenose em questão foi baseada no valor do mesmo: FFR ≥ 0,75 a lesão não era tratada; FFR < 0,75 a lesão era tratada. RESULTADOS: Foi possível obter o FFR em 452 lesões (96%). O diâmetro de estenose médio foi de 62 ± 12% e o FFR médio foi 0,67 ± 0,17. Em 68% das lesões a estratégia planejada de acordo com a angiografia foi seguida e em 32% houve mudança de estratégia com base no FFR. Em 100 estenoses (22%) nenhuma ICP foi realizada e em 44 estenoses (10%) algum tipo de revascularização foi feita apesar da lesão não ter sido considerada significativa pela angiografia. Em 48% dos pacientes houve pelo menos 1 estenose na qual a decisão terapêutica foi mudada após a avaliação fisiológica invasiva. CONCLUSÕES: Neste estudo prospectivo, não seletivo e que representa o mundo real das ICP, 32% das lesões coronárias e 48% dos pacientes teriam recebido tratamento diferente se somente a estimativa visual da angiografia fosse seguida, enfatizando a utilidade da avaliação fisiológica invasiva como uma importante ferramenta auxiliar nas tomadas de decisão durante as intervenções percutâneas.
BACKGROUND: In complex and multivessel coronary artery disease, it is often difficult to assess which lesions are associated with reversible ischemia and should be stented. Fractional flow reserve (FFR) is a well established methodology to indicate which lesions are culprit or not. Yet, frequently the selection of lesions to be stented is based on the angiogram alone. The main aim of this study in patients admitted for elective percutaneous coronary intervention (PCI) was to evaluate the percentage of change in the initial therapeutic plan if decision is based on FFR measurement rather than on angiographic assessment. METHODS: All patients scheduled for elective PCI between October 2004 and April 2005 were included in the study except those with chronic total occlusion. Two hundred and fifty patients and 471 arteries with a stenosis ≥ 50% by visual estimation and initially selected to be stented were assessed by FFR measurements. Before PCI, 3 cardiologists independently reviewed the diagnostic angiogram and classified lesions as those that should be treated by PCI by visual assessment and those that should not be treated. Next, the decision to stent was based upon FFR measurement. If FFR was < 0.75, actual stenting was performed; if FFR was ≥ 0.75, no interventional treatment was given. RESULTS: It was possible to perform optimal pressure measurements and FFR determinations in 452 (96%) lesions. Mean diameter stenosis was 62 ± 12% and average FFR 0.67 ± 0.17 for the entire group. In 68% of the stenoses initial therapeutic strategy as assessed from the angiogram was followed and in 32% there was a change in the planned approach based on FFR. In 100 stenoses (22%) PCI planned on the basis of angiography was deferred, and in 44 stenoses (10%) revascularization was performed although such stenosis was not considered as ischemia-related on the angiogram. In 48% of the patients there was at least one lesion in which the treatment decision was changed after physiologic measurements. CONCLUSIONS: In this prospective, non-selective, but complete study representing the real world of PCI, 32% of the coronary stenoses and 48% of patients would have received a different treatment if solely the visual assessment by angiography was followed, stressing the utility of physiologic assessment in refining decision making during PCI.
9

Redondo, Fernanda Roberta Roque. "Efeitos do uso de esteróides anabolizantes associados ao treinamento físico de natação sobre o fluxo sangüíneo para o miocárdio de ratos normotensos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/39/39132/tde-20042007-100232/.

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O uso indiscriminado de recursos ergogênicos como os esteróides anabolizantes vêm se tornando um problema crescente em diversos segmentos da população, além do meio atlético, tendo como finalidade a obtenção de melhor desempenho físico ou simplesmente melhor aparência física, porém muitas vezes sem a preocupação com os riscos dos efeitos colaterais promovidos por esta prática. No presente trabalho estudamos os efeitos da associação do uso de doses suprafisiológicas de esteróides anabolizantes e do treinamento físico aeróbio de natação sobre o fluxo sangüíneo coronário de ratos normotensos, verificando a participação da adenosina como um dos possíveis mecanismos de regulação deste fluxo, além de alterações estruturais cardíacas que poderiam influenciar na perfusão sangüínea cardíaca. Ao observarmos somente o efeito do treinamento físico, verificamos que o mesmo foi eficaz em promover adaptações benéficas ao sistema cardiovascular, como a presença de hipertrofia cardíaca fisiológica e melhora no fluxo sangüíneo coronário em repouso, provavelmente mediado por uma maior formação de adenosina circulante e cardíaca. O uso de esteróides anabolizantes associado ao treinamento físico atenuou os efeitos benéficos promovidos pelo treinamento, observando-se a presença de hipertrofia cardíaca acompanhada por redução de débito cardíaco e fluxo sangüíneo coronário, mediado por menor produção de adenosina circulante, além de prejuízo na resposta vasodilatadora à acetilcolina, demonstrando uma provável disfunção endotelial e redução na densidade capilar cardíaca, caracterizando desta forma, um quadro patológico
The abusive use of ergogenic resources as the anabolic steroid became an increasing problem in several segments of the population, beyond the athletical way, searching for better performance or physical appearance, without being worried about the risks of the collateral effects promoted by this practice. In the present work we studied the effects of the use of supraphysiological doses of anabolic steroids associated with aerobic swimming training on the coronary blood flow of normotensive rats, investigating the participation of adenosine as one of the possible mechanisms of blood flow regulation, besides the cardiac structural alterations that could influence the coronary blood perfusion. The effect of the physical training was efficient to promote beneficial adaptations of the cardiovascular system, as the presence of physiological cardiac hypertrophy and improves the coronary blood flow at rest, probably mediated by a higher circulating and cardiac adenosine production. The use of anabolic steroids associated with the swimming training attenuated the beneficial effect promoted by training, being observed the presence of cardiac hypertrophy, followed by reduction of cardiac output and coronary blood flow, mediated by lower circulating adenosine production, besides the impairment of the vasodilator response to the acetylcholine, demonstrating a probable endothelial dysfunction and reduction of the cardiac capillary density, characterizing in this way, a pathological state
10

Lima, Marta Fernandes. "Valor prognóstico da reserva de fluxo coronário e miocárdico obtida pela ecocardiografia contrastada em pacientes com cardiomiopatia dilatada de origem não isquêmica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-30072012-081401/.

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Apesar dos avanços no entendimento da fisiopatologia e dos recursos terapêuticos atualmente disponíveis, a cardiomiopatia dilatada (CMD) permanece como uma condição com alta mortalidade, sendo que a disfunção microvascular é um dos mecanismos relacionados à piora da função cardíaca. Nos últimos anos, novas técnicas de ecocardiografia vêm sendo utilizadas para avaliação da disfunção microvascular, incluindo a medida de velocidade de fluxo coronário pelo Doppler da artéria coronária descendente anterior (ADA), e a análise quantitativa do fluxo miocárdico pela ecocardiografia com perfusão miocárdica em tempo-real (EPMTR). No presente estudo, avaliamos o valor prognóstico da reserva de velocidade de fluxo coronário (RVFC), obtida pelo Doppler da ADA, e da reserva de fluxo miocárdico (RFM), obtida pela EPMTR, para predizer morte e transplante cardíaco em pacientes com CMD de origem não isquêmica. Adicionalmente, avaliamos se as medidas de reserva de fluxo acrescentam valor prognóstico sobre variáveis clínicas e ecocardiográficas que já são conhecidas como preditores de eventos nesta população. Estudamos 195 pacientes com CMD (130 homens, média etária 54 ± 12 anos) que apresentavam fração de ejeção do ventrículo esquerdo inferior a 35% pelo ecocardiograma e ausência de sinais de doença arterial coronária obstrutiva por angiografia coronária invasiva ou por método não invasivo (cintilografia de perfusão miocárdica ou angiotomografia de coronárias). Foram analisados parâmetros ecocardiográficos convencionais de função sistólica e diastólica do ventrículo esquerdo em repouso. A velocidade de fluxo coronário foi determinada pelo Doppler pulsado na ADA e a dinâmica das microbolhas no miocárdio foi quantificada pela EPMTR utilizando programas computacionais específicos, tanto em repouso como durante o estresse pelo dipiridamol (0,84 mg/Kg). As RVFC, RFM e reserva de velocidade de repreenchimento de microbolhas no miocárdio (reserva ) foram obtidas pela relação entre os parâmetros de fluxo durante a hiperemia e em repouso, sendo consideradas diminuídas quando os valores estavam abaixo de 2,0. O tempo médio de acompanhamento foi de 29 meses (variando de 6 a 69 meses). Neste período, 45 pacientes (24%) apresentaram eventos, sendo 43 mortes de causa cardíaca e 2 transplantes cardíacos. Na análise univariada foram preditores de eventos: etiologia chagásica, classe funcional de insuficiência cardíaca, uso de inibidores da enzima conversora de angiotensina e/ou bloqueadores dos receptores de angiotensina II (fator protetor), diâmetros ventriculares e do átrio esquerdo, volumes ventriculares, fração de ejeção, disfunção diastólica, grau de insuficiência mitral, RVFC, RFM e reserva . Na análise multivariada, foram preditores independentes de eventos o diâmetro do átrio esquerdo (razão de chances = 1,16 por unidade de aumento; intervalo de confiança 95% = 1,078 1,264; p<0,001) e a reserva diminuída (razão de chances = 3,219; intervalo de confiança 95% = 1,178 8,795; p<0,001). No modelo sequencial de predição de eventos, fração de ejeção e diâmetro do átrio esquerdo adicionaram valor prognóstico às variáveis clínicas (aumento do qui-quadrado de 15,2 para 58,5; p < 0,001). A reserva adicionou poder ao modelo (qui-quadrado de 70,2; p<0,001). Concluímos que tanto a RVFC, obtida pelo Doppler da ADA, como a RFM e reserva , obtidas pela EPMTR sob estresse pelo dipiridamol, são preditoras de morte e transplante cardíaco em pacientes com CMD não isquêmica. Entretanto, somente o diâmetro do átrio esquerdo e a reserva mostraram valor prognóstico independente e incremental sobre variáveis clínicas e ecocardiográficas que já são conhecidas como preditores de eventos nesta população
Despite advances in understanding of the pathophysiology and therapeutic approaches, dilated cardiomyopathy (DCM) remains as a condition with high mortality and one of the mechanisms involved in this process seems to be microvascular dysfunction. Recently, new echocardiographic techniques have been incorporated in the clinical practice and used for the assessment of microvascular dysfunction, including evaluation of left anterior descending coronary artery (LAD) by Doppler and quantitative analysis of myocardial flow by real-time myocardial perfusion echocardiography (RTMPE). In the present study, we evaluated the prognostic value of coronary flow velocity reserve (CFVR), obtained by transthoracic echocardiography, and parameters of myocardial flow reserve (MFR), obtained by RTMPE for predicting cardiac death and heart transplantation in patients with nonischemic DCM. In addition, we sought to detect the incremental value of flow reserve over clinical and echocardiographic parameters already known as predictors of events in this population. We studied 195 patients with DCM (130 men, mean age 54 ± 12 years) who had left ventricular ejection fraction (LVEF) less than 35% by echocardiography and no signs of obstructive coronary artery disease by invasive coronary angiography or noninvasive methods (nuclear medicine or angiography by computed tomography). We assessed conventional echocardiographic parameters of systolic and diastolic left ventricular function at rest. Coronary flow velocity was determined by pulsed Doppler in LAD and dynamics of microbubbles in the myocardium was measured by RTMPE using specific computer programs, both at rest and during dipyridamole stress (0.84 mg/kg). CFVR, MFR and the reserve of velocity of microbubbles in the myocardium ( reserve) were obtained as the ratio between parameters of flow during hyperemia and at rest, being considered abnormal when these were below 2.0. The mean follow-up was 29 months (ranging from 6 to 69 months). During this period, 45 patients (24%) had events, 43 cardiac deaths and 2 heart transplantations. In the univariate analysis, predictors of events were: Chagas disease, New York Heart Association functional class, use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blocker (protective effect), left ventricular and atrial diameters, left ventricular volumes, LVEF, diastolic dysfunction, degree of mitral regurgitation, CVFR, MFR and reserve. By multivariate analysis, the only independent predictors of events were the left atrial diameter (OR = 1.16, 95% confidence interval = 1.078 to 1.264, p <0.001) and reserve 2.0 (OR = 3.219, confidence interval 95 % = 1.178 to 8.795, p <0.001). In the sequential model of events prediction, LVEF and left atrial diameter added prognostic value over clinical factors (chi-square from 15.2 to 58.5; p<0.001). reserve added power to the model (chi-square = 70.2, p<0.001). We concluded that CVFR, obtained by Doppler in LAD, MFR and reserve, obtained by dipyridamole stress RTMPE, are predictors of cardiac death and heart transplantation in patients with nonischemic DCM. However, only left atrial diameter and depressed reserve showed independent and incremental predictive value beyond that provided by current known prognostic clinical and echocardiographic factors

Частини книг з теми "Flux coronaire":

1

Isenberg, Gerrit, and Vladimir Ganitkevich. "Na-Ca Exchange in Isolated Coronary Myocytes: A Study Combining Voltage Clamp and Ca2+ Fluorometry." In Ion Flux in Pulmonary Vascular Control, 57–66. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2397-0_5.

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2

Kellner-Weibel, Ginny, Margarita de la Llera-Moya, Sandhya Sankaranarayanan, and George H. Rothblat. "In Vitro Studies and Mass Flux of Cholesterol Between Serum and Macrophages." In High Density Lipoproteins, Dyslipidemia, and Coronary Heart Disease, 83–88. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-1059-2_10.

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Тези доповідей конференцій з теми "Flux coronaire":

1

Fayssal, Iyad, and Fadl Moukalled. "A Numerical Analysis of the Hemodynamic Functionality of Human Coronary Stenosis Under Different Physiologic Conditions and Boundary Condition Formulations." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4820.

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Abstract Coronary artery disease (CAD) is among the foremost causes for human death worldwide. This study aims at investigating the performance of different boundary condition model types to characterize CAD functional significance. In addition, alternate models to estimate FFR using any different combination of boundary conditions at inlet and outlet were analyzed. In the first type of boundary condition, an outflow resistance model is used combined with a fixed pressure at inlet. In the second model of boundary conditions, constant pressure values are imposed at the domain inlet and outlet/s sections. In the third model, a zero diffusion flux is applied at outlet with a pre-specified flow rate at inlet. Numerical simulations performed on healthy and stenosed idealized and physiological arterial models revealed the superiority of the first type of boundary condition to directly capture the level of ischemia in diseased arteries. However, in this model, special numerical treatment at the outflow boundary is needed to dampen pseudo numerical reflections entering the computational domain. Alternative simple methods are developed to tackle the problem incurred in the second and third types of boundary condition types. The alternate models are effective for carrying extensive parametric studies with minimal computational effort. The new developed methods allow results generated via generic simulations under any specified boundary condition type to correctly estimate CAD functional significance. The obtained surrogate models account for the effects of the patient-specific physiologic parameters and can be easily incorporated without modifying existing CFD codes. Moreover, where it is unfeasible to experimentally incorporate the downstream effects of a given diseased arterial segment, an important aspect the alternative models provide is that they can be easily adopted by experimentalists through building in-vitro arterial models to assess the functional significance of the obstruction caused by the disease and its relation to any given patient specific physiologic parameter.

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