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Li, Yao. "Contributions of TRPM4 and Rho Kinase to Myogenic Tone Development in Cerebral Parenchymal Arterioles." ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/464.
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Cerebral parenchymal arterioles (PAs) play a critical role in assuring appropriate blood flow and perfusion pressure within the brain. PAs are unique in contrast to upstream pial arteries, as defined by their critical roles in neurovascular coupling, distinct sensitivities to vasoconstrictors, and enhanced myogenic responsiveness. Dysfunction of these blood vessels is implicated in numerous cardiovascular diseases. However, treatments are limited due to incomplete understanding of the fundamental control mechanisms at this level of the circulation. One of the key elements within most vascular networks, including the cerebral circulation, is the presence of myogenic tone, an intrinsic process whereby resistance arteries constrict and reduce their diameter in response to elevated arterial pressure. This process is centrally involved in the ability of the brain to maintain nearly constant blood flow over a broad range of systemic blood pressures. The overall goal of this dissertation was to investigate the unique mechanisms of myogenic tone regulation in the cerebral microcirculation. To reveal the contributions of various signaling factors in this process, measurements of diameter, intracellular Ca2+ concentration ([Ca2+]i), membrane potential and ion channel activity were performed. Initial work determined that two purinergic G protein-coupled receptors, P2Y4 and P2Y6 receptors, play a unique role in mediating pressure-induced vasoconstriction of PAs in a ligand-independent manner. Moreover, a particular transient receptor potential (TRP) channel in the melastatin subfamily, i.e. TRPM4, was also identified as a mediator of PA myogenic responses. Notably, the observations that inhibiting TRPM4 channels substantially reduces P2Y receptor-mediated depolarization and vasoconstriction, and that P2Y receptor ligands markedly activate TRPM4 currents provide definitive evidence that this ion channel functions as an important link between mechano-sensitive P2Y receptor activation and the myogenic response in PAs. Next, the signaling cascades that mediate stretch-induced TRPM4 activation in PA myocytes were explored. Interestingly, these experiments determined that the RhoA/Rho kinase signaling pathway is involved in this mechanism by facilitating pressure-induced, P2Y receptor-mediated stimulation of TRPM4 channels, leading to subsequent smooth muscle depolarization, [Ca2+]i increase and contraction. Since Rho kinase is generally accepted as a 'Ca2+-sensitization' mediator, the present, contrasting observations point to an underappreciated role of RhoA/Rho kinase signaling in the excitation-contraction mechanisms within the cerebral microcirculation. Overall, this dissertation provides evidence that myogenic regulation of cerebral PAs is mediated by mechano-sensitive P2Y receptors, which initiate the RhoA/Rho kinase signaling pathway, subsequent TRPM4 channel opening, and concomitant depolarization and contraction of arteriolar smooth muscle cells. Revealing the unique mechanochemical coupling mechanisms in the cerebral microcirculation may lead to development of innovative therapeutic strategies for prevention and treatment of microvascular pathologies in the brain.
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Catherall, Mark. "Modelling the role of nitric oxide in cerebral autoregulation." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c15a49be-791f-47d5-91a0-f507f5856063.
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Malfunction of the system which regulates the bloodflow in the brain is a major cause of stroke and dementia, costing many lives and many billions of pounds each year in the UK alone. This regulatory system, known as cerebral autoregulation, has been the subject of much experimental and mathematical investigation yet our understanding of it is still quite limited. One area in which our understanding is particularly lacking is that of the role of nitric oxide, understood to be a potent vasodilator. The interactions of nitric oxide with the better understood myogenic response remain un-modelled and poorly understood. In this thesis we present a novel model of the arteriolar control mechanism, comprising a mixture of well-established and new models of individual processes, brought together for the first time. We show that this model is capable of reproducing experimentally observed behaviour very closely and go on to investigate its stability in the context of the vasculature of the whole brain. In conclusion we find that nitric oxide, although it plays a central role in determining equilibrium vessel radius, is unimportant to the dynamics of the system and its responses to variation in arterial blood pressure. We also find that the stability of the system is very sensitive to the dynamics of Ca2+ within the muscle cell, and that self-sustaining Ca2+ waves are not necessary to cause whole-vessel radius oscillations consistent with vasomotion.
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MOINARDEAU, VERONIQUE. "Traitement curatif du vasospasme arteriel cerebral apres hemorragie meningee par l'association remplissage vasculaire, hypertension arterielle moderee et nimodipine i. V." Lille 2, 1989. http://www.theses.fr/1989LIL2M308.
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Helps, Stephen. "Pathophysiological basis of cerebral arterial air embolism /." Title page, table of contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phh484.pdf.
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MARTINS, Islane Cristina. "Morfologia do círculo arterial cerebral em humanos: hipoplasia do segmento A1 da artéria cerebral anterior e padrão fetal da artéria cerebral posterior." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/20007.
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FACEPE
O círculo arterial cerebral é um polígono anastomótico na base do encéfalo que comunica o sistema carotídeo com o sistema vértebro-basilar e as carótidas entre si. Há muitas variações morfológicas nesse polígono e possíveis diferenças entre os sexos, particularmente no segmento A1 da artéria cerebral anterior e na origem da artéria cerebral posterior (ACP). O objetivo do presente estudo foi analisar comparativamente a frequência de hipoplasia do segmento A1 e do padrão fetal da artéria cerebral posterior no homem e na mulher. Foram analisadas retrospectivamente 848 angiografias por ressonância magnética arterial, em 426 homens e 422 mulheres, respectivamente, que se submeteram ao exame no Centro de Diagnóstico Multimagem. Os exames foram escolhidos aleatoriamente entre 1.000 angiorressonância realizadas entre 2010 e 2016, independente do motivo da solicitação médica. Hipoplasia do segmento A1 foi definido por analise qualitativa, quando havia uma nítida assimetria entre os dois segmentos A1 direito e esquerdo bem como o padrão fetal da artéria cerebral posterior. Para análise de hipoplasia foram medidos os diâmetros dos segmentos A1. Para análise do padrão fetal (diâmetro da ACP na origem da artéria carótida>diâmetro do segmento P1) foram analisadas 1.296 artérias carótidas em 648 indivíduos. Na análise estatística utilizouse o teste exato de Fisher. Os homens 152/326 (46,6%) apresentaram hipoplasia de A1 em comparação com 108/322 (33,5%) das mulheres (p<0,01, OR=1,7; IC95% 1,3-2,4). A hipoplasia de A1 nos homens foi mais frequente a direita (20% vs. 15%, p<0,01). O padrão fetal foi mais comum nas mulheres 151/644 (23,4%) do que em homens, 100/652 (15,3%) (p<0,001, OR=1,7; IC95% 1,3-2,2). As mulheres também apresentam mais padrão fetal bilateral do que os homens (8,0% vs. 3,4%; p<0,01; OR=0,4; IC 0,2-0,8). A hipoplasia do segmento A1 da artéria cerebral anterior é mais frequente nos homens e nas mulheres há uma maior frequência do padrão fetal da artéria cerebral posterior.
The Circle of Willis is an anastomotic polygon encephalon base that communicates the carotid system with vertebrobasilar system and carotid each other. There are lots of morphological variations that polygon and possible differences between genders particularly in the A1 segment of the anterior cerebral artery and the origin of the posterior cerebral artery (PCA) which are risk factors for anatomical brain aneurysms. The purpose of this study was to comparatively analyze the frequency of hypoplasia of the segment A1 and fetal type of cerebral posterior artery in man and woman. It was retrospectively reviewed 648 magnetic resonance angiographies in 326 men and 322 women, respectively. The tests were randomly chosen among about a thousand magnetic resonance angiographic performed between 2010 and 2016 in Multimagem Diagnostic Center, regardless of the medical reason request. Hypoplasia of the A1 segment was defined by qualitative analysis, when there was a clear asymmetry between the two segments A1, right and left. For hypoplasia analysis were also measured diameters of segments A1. For hypoplasia analysis were also measured diameters of segments A1. For analysis of the fetal type (diameter of the ACP origin of the carotid artery> diameter of the P1 segment of the ACP) were analyzed 1,296 carotid arteries (right and left) in 648 individuals. Statistical analysis was performed using Fisher's exact test. In men 152/326 (46.6%) showed hypoplasia A1 compared to 108/322 (33.5%) of women (p <0.01, OR = 1.7; 95% CI, 1.3-2, 4). Hypoplasia A1 was more common in men right (20% vs. 15%, p <0.01). Fetal type was more common in women 151/644 (23.4%) than in men (100/652; 15.3%) (p <0.001, OR = 1.7; 95% CI, 1.3-2, two). Women also have more bilateral fetal rate than men (8.0% vs. 3.4%; p <0.01). In conclusion, hypoplasia of the A1 segment of the anterior cerebral artery is more common in men and in women there is a greater frequency of fetal type of the posterior cerebral artery. Keywords: Circle of Willis
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Chan, Marcelo. "The design and development of a cerebral embolic implant." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/17767.
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Wesołowski, Roman. "Development of arterial spin labelling methods for monitoring cerebral haemodynamics." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/13854/.
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The work described in this thesis was carried out at the Sir Peter Mansfield Magnetic Resonance Centre at the University of Nottingham between March 2006 and December 2009. All work described in this thesis was performed by the author, except where indicated. This thesis aims to develop and implement ASL techniques to measure haemodynamic responses to neural activity. The development of a new technique Double Acquisition Background Suppression (DABS) is presented as a remedy for a newly discovered artefact affecting Philips Achieva 7 T scanners and other sources of variation in baseline signals such as physiological noise. The new technique (DABS) was developed for simultaneous acquisition of ASL (with suppressed static tissue signal) and BOLD data using the FAIR scheme. This method not only provided a solution to obtaining ASL data at 7 T, despite the Roman Artefact, but also proved to reduce the contribution of physiological noise to ASL images, which is problematic, especially at ultra-high magnetic field strengths. The statistical verification was carried out based on the neural activation induced by a finger-tapping stimulus. A simplified model for quantifying CBVa.with the Look-Locker sampling method is proposed in this thesis to overcome the need for the Step-wise Compartmental Model (SCM). The Look-Locker sampling scheme acquires multiple readout pulses following the labelling and provides an estimation of transit time as well as CBVa. Here the simplified model is used to assess changes due to visual stimulation and validated against the SCM model. The application of LL-FAIR to form CBF and CBVa weighted data with improved SNR compared to traditional single TI FAIR technique is then shown. This method uses a summation over LL-EPI readout pulses and is used to asses the temporal characteristics and absolute changes in CBF and CBVa haemodynamic responses to a short (4.8 s) and long (9.6 s) visual stimulus. LL-FAIR methods are then used to appraise the neural coupling of haemodynamic parameters and assess Grubb's relationship. CBF and CBVa. Data were collected together with CBVtot data from a bolus injection of contrast agent. Assessing Grubb's power-law (CBVtot = CBFCI:)for neuronal activation, which was originally derived in primates during a steady state response of hypercapnia, a was found in this human study to be between 0.22 ± 0.08 and 0.29, dependent on the analysis method. In addition, the power-law relationship between CBVtot and CBVa.was assessed, and resulted in a similar relation, yielding aTA = 0.42 ± 0.14 and 0.40. Since CBF is thought to be driven by CBVa.the power-law between these parameters was also tested with a value of aFA = 1.35 ± 0.64 and 1.21, found in close agreement with earlier animal work.
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Willie, Christopher Kenneth. "Cerebral blood flow in man : regulation by arterial blood gases." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/47074.
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Due to the high metabolic rate of brain tissue and nominal substrate storage, brain perfusion must be precisely regulated to ensure continuous delivery of oxygen and substrates. Cerebral blood flow (CBF) is principally regulated by tissue metabolism, perfusion pressure, autonomic nervous activity, and the partial pressures of arterial oxygen (PaO₂)and carbon dioxide (PaCO₂) – an integrative process thus involving the marked influence of pulmonary gas exchange and cardiovascular function, in addition to intracranial mediators of cerebrovascular resistance. This thesis explicates the roles of PaO₂ and PaCO₂ in human regulation of regional CBF. In study 1, to elucidate their discrete roles, PaO₂ and PaCO₂ were independently manipulated at sea level through the widest range tolerated in humans. Flow reactivity to hypocapnia (low PaCO₂) and hypoxia (low PaO₂) was greater in the vertebral (VA) than internal carotid (ICA) artery, whereas similar reactivity was observed during hypercapnia (high PaCO₂) and hyperoxia (high PaO2₂. Cerebral oxygen delivery was well protected except in cases of extreme hypocapnia. The ventilatory response to hypoxia mitigates falling PaO₂ and reduces PaCO₂, particularly during initial exposure to high altitude. Study 2 assessed regional CBF during ascent to 5050m and every 12 hours during the first 3 days of acclimatization. Although total CBF increased by ~50% and was modestly related to reductions in oxygen saturation of hemoglobin, no regional CBF differences were observed. To extend these findings, Study 3 aimed to determine if cerebrovascular responses to changes in PaO₂ and PaCO₂ differed at 5050m compared to sea level. Despite respiratory alkalosis and partial metabolic compensation at 5050m restoration of PaO₂ to sea level values decreased CBF, and CBF sensitivity to acutely altered PaCO₂ remained similar to sea level. To elucidate the interactive effect on CBF of profound hypoxemia and hypercapnia, study 4 examined the temporal changes in elite breath-hold divers during maximum apneas. Despite 40-50% reductions in arterial oxygen content, CBF elevations were regionally similar (up to +100%) thereby facilitating maintenance of brain oxygen delivery throughout apnea. Although the regulation of CBF is multifaceted, the cerebrovasculature prioritizes oxygen delivery and adjusts to chronic changes in arterial blood gases.
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Nasi, Luiz Antonio. "Manipulação da pressão arterial no acidente vascular cerebral isquêmico agudo." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/132167.
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Figueiredo, P. M. "Measuring brain perfusion using arterial spin labelling by magnetic resonance imaging." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275320.
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Modaresi, Kamran Bahari. "Computerised techniques for improved imaging and monitoring of the arterial circulation." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281685.
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Liu, Yi. "A study of mathematical modelling and signal processing of cerebral autoregulation." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273880.
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DENIZART, MARIE-ODILE. "Anomalies du profil tensionnel a la phase aigue de l'accident vasculaire cerebral." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX20111.
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Gibert, Guillaume. "Quantification of the Cerebral Perfusion with the Arterial Spin Labelling 3D-MRI method. Quantification of the Cerebral Perfusion with the Arterial Spin Labelling 3D-MRI method." Thesis, KTH, Skolan för teknik och hälsa (STH), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148020.
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The Arterial Spin Labelling (ASL) method is a Magnetic Resonance technique used toquantify the cerebral perfusion. It has the big advantage to be non-invasive so doesn’tneed the injection of any contrast agent. But due to a relatively low Signal-to-NoiseRatio (SNR) of the signal acquired (only approximately 1% of the image intensity), ithas been hampered to be widely used in a clinical setting so far.The primary objective of this project is to make the method more robust by improvingthe quality of the images, the SNR, and by reducing the acquisition time. DifferentASL protocols with different sets of parameters have been investigated. The modificationsperformed on the protocol have been investigated by analyzing images acquired onhealthy volunteers. An optimized protocol leading to a good trade-off between the differentaspects of the method, has been suggested. It is characterized by a 3:43:44:0mm3with a two-segment acquisition.A more advanced ASL method implies the acquisition of images at different inversiontimes (TI), which is called the mutli-TI method. The influence of the range of TI used inthe method has been explored. An optimized TI range (from 410ms to 3860ms, sampledevery 150ms) has been suggested to make the ASL method as performant as possible.A numerical model and a fitting algorithm have been used to extract the informationon the perfusion from the images acquired. Different models have been investigated aswell as their influence on the reliability of the results.Finally, a criterion has been implemented to evaluate the reliability of the results sothat the clinician or the user of the method can figure out how much he can count onthe results provided by the method.
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Lacour, Jean-Christophe. "Les infarctus arteriels cerebraux de l'adulte jeune : etude prospective de 152 observations." Nancy 1, 1994. http://www.theses.fr/1994NAN11100.
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Paschoal, André Monteiro. "Otimização do contraste em Arterial Spin Labeling multifase." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-29092015-101918/.
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Imagem por ressonância magnética tem sido um dos principais métodos para a aquisição de imagens para diagnósticos na medicina, em especial para a obtenção de medidas do cérebro. Apesar de se mostrar muito eficiente, o método atualmente utilizado para a realização da ressonância em hospitais e centros de diagnósticos, em alguns casos, necessita da aplicação de um contraste de gadolínio intravenoso. Essa injeção do contraste pode mostrar-se um tanto quanto invasivo, podendo em alguns casos resultar em algumas reações indesejadas nos pacientes. Em vista disso, um método que tem sido bastante estudado recentemente e muito promissor é o de Arterial Spin Labeling (ASL). Este método tem como sua principal vantagem o fato de não ser invasivo e de possibilitar a quantificação da perfusão sanguínea cerebral (CBF). No presente trabalho, foi feita uma otimização do contraste na aquisição das fases mais tardias da metodologia de ASL em múltiplas fases. Isso foi feito através de uma modulação do angulo de flip e é particularmente importante para a análise das imagens de pacientes com problemas neurovasculares, principalmente aqueles associados ao retardo nos tempos de trânsito do sangue arterial. Também, foi realizada toda a obtenção e processamento de dados para a avaliação da perfusão sanguínea cerebral utilizando o método proposto.Magnetic resonance imaging has been one of the major methods to acquire images for medical diagnoses, specially, for obtaining brain images. Although the major method using magnetic resonance used today has high efficiency, in some cases it needs an injection of intravascular contrast agent, like gadolinium. This contrast agent application can be a lot invasive for the patient, in extremes cases resulting to allergic reactions the patient. Therefore, a method that has been studied recently and is very promising is the Arterial Spin Labeling (ASL). This method has the major advantage the feature that it is completely non invasive for the patient and it allows to quantify the perfusion value. In this work, it was implemented an optimization of the contrast in the late phases of ASL multiphase acquisition. It was made using a modulation of the flip angle and it is critical to analyze images from patients with some neurovascular disease, especially those associated with arterial blood transit time delay. Besides that, it was made all data acquisition and data processing for the brain perfusion evaluation using the proposed method.
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Reckziegel, Sueli Hoff. "Vascularização arterial da região hipocampal em Hydrochoerus hydrochaeris (capivara)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6277.
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O objetivo deste trabalho foi de angariar conhecimentos sobre a vascularização arterial da região hipocampal em Hydrochoerus hydrochaeris, descrevendo através da repleção vascular e dissecção anatômica a artéria cerebral caudal e ramos dos ramos terminais da artéria basilar que fazem o aporte sanguíneo para o hipocampo, mapeando seus territórios. Utilizou-se 68 hemisférios cerebrais de Hydrochoerus hydrochaeris, machos e fêmeas, injetados com Látex 603 ou Látex Frasca, pigmentado em vermelho e azul, fixados em solução de formol a 20%. A artéria cerebral caudal originou-se do ramo terminal da artéria basilar rostral à raiz do nervo oculomotor. Logo após sua emergência lançou a artéria tectal rostral em 27,9% dos casos. Em seguida cruzou os pedúnculos cerebrais, dorsalmente aos corpos geniculados e ao pulvinar, emitindo pequenos ramos perfurantes para estas estruturas. Enquanto a artéria cerebral caudal percorreu a superfície do giro para-hipocampal, dorsalmente foram emitidos pequenos ramos que penetraram no sulco hipocampal, rostromedialmente a artéria coroidéia caudal e caudalmente de três a onze ramos corticais. A artéria coroidéia caudal apresentou-se única em 85,3% dos casos, dupla em 13,2% e ausente em 1,5%. A artéria coroidéia caudal apresentou-se única em 85,3% dos casos, dupla em 13,2% e ausente em 1,5%. A artéria coroidéia rostral originou-se do ramo terminal da artéria basilar logo após a emergência da artéria cerebral caudal anastomosando-se com a artéria coroidéia caudal suprindo o plexo corióideo do terceiro ventrículo e os ventrículos laterais. Ao longo de seu curso tanto a artéria coroidéia caudal como a artéria coroidéia rostral lançaram ramos hipocampais que anastomosaram-se entre si e com os ramos emitidos pela artéria cerebral caudal formando verdadeiras redes. Os ramos terminais da artéria cerebral caudal cruzaram o esplênio do corpo caloso para distribuirem-se na superfície caudomedial do hemisfério cerebral. Os limites territoriais da artéria cerebral caudal compreenderam a face caudal do lobo piriforme, a face tentorial, a porção retroesplênica da face medial e também uma estreita área da face dorsolateral do hemisfério cerebral margeando as fissuras longitudinal dorsal e transversa do cérebro. A vascularização arterial do hipocampo da capivara foi suprida por ramos originados da artéria cerebral caudal e pela artéria coroidéia rostral.
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Petric, Martin Peter. "Quantitative multi-slice cerebral perfusion imaging using arterial spin labelling MR techniques." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33821.
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This thesis presents the development and implementation of a quantitative multi-slice cerebral perfusion imaging technique using magnetic resonance imaging. An acquisition sequence capable of acquiring up to 9 slices was designed and implemented into two final pulse sequences: an interleaved perfusion/BOLD (blood oxygenation level dependent) sequence and a perfusion-only sequence. A number of practical imaging issues were addressed and resolved, including the design of an appropriate inversion pulse for labelling of arterial spins, spatial offsetting of this pulse for use in the arterial spin labelling technique chosen for implementation, and the design of various saturation pulses necessary for quantification of the technique. Experimental validation of the quantitative multi-slice perfusion technique was performed by measuring visual cortex cerebral blood flow (CBF) values in a group of 8 subjects using a block-design visual stimulus paradigm. Results indicated good sequence stability and CBF measurements agreed well with quantitative values found in the literature.
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Gallichan, Daniel. "Measuring cerebral blood flow using arterial spin labelling with magnetic resonance imaging." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442955.
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Xie, Jingyi. "Quantitative measurement of regional cerebral blood flow with arterial spin labelling imaging." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504384.
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Nunes, Sílvia Daniela de Macedo Teixeira. "Risco cerebrovascular e arterial periférico numa população com aterosclerose coronária limitada." Master's thesis, Universidade da Beira Interior, 2012. http://hdl.handle.net/10400.6/1107.
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Objectivos: Neste trabalho de investigação procurou responder a 3 objectivos primordiais: (1) determinar se o score de cálcio baixo identifica ou não indivíduos com escasso atingimento aterosclerótico nos territórios cerebrovascular e vascular periférico; (2) determinar se o reduzido envolvimento coronário, traduzido por um score de cálcio coronário baixo, se traduz em reduzida ocorrência de eventos cardiovasculares major; e (3) correlacionar esse risco com as escalas clássicas.
Introdução: Estudos recentes mostram que a quantificação de cálcio nas artérias coronárias, score coronário de cálcio, é um excelente marcador do processo aterosclerótico, melhorando a previsão do risco DCV, sobretudo em indivíduos de risco intermédio. O cálcio coronário (CC) é encontrado em lesões avançadas, mas também pode estar presente em pequenas quantidades em lesões ateroscleróticas recentes que se desenvolvem durante a 2ª ou 3ª década de vida. A quantidade de CC aumenta com a idade, embora a taxa de progressão do CC na idade adulta esteja relacionada com a prevalência de factores de risco em idades precoces. Por esse motivo, a prevalência de um SCC mensurável é inferior em pessoas com menos fatores de risco na sua juventude.
Métodos: Realizou-se um estudo observacional composto por 2 partes, uma prospetiva e outra retrospetiva. O estudo prospetivo englobou 54 doentes, que completaram o estudo, nos quais o SCC determinado, no segundo semestre de 2010, foi inferior ou igual a 100. Este estudo foi dividido em duas partes realizadas em tempos diferentes. Numa primeira fase, convocou-se os doentes e averiguou-se os factores de risco presentes e ainda se calculou o ITB. Numa segunda fase foram chamados a realizar o eco-doppler carotídeo. O estudo retrospetivo consistiu na consulta dos processos digitais e em papel de 119 doentes que realizaram o Angio-TC no segundo semestre de 2009 e no primeiro semestre de 2010, nos quais o SCC obtido foi inferior ou igual a 100. Os resultados obtidos no presente estudo foram analisados com recurso aos programas de análise estatística de dados SPSS Statistics Vs 19 e Microsoft Office Excel 2010.
Resultados: No estudo prospetivo, 64,8% da amostra era do sexo feminino (35 indivíduos) e a idade média era 64 ±9,6 anos. Cinquenta e três por cento da amostra apresentou um SCC de 0. A quantificação de risco pelas escalas clássicas foi em média 11,8±9,7% e 2,8±3,6% segundo a FRS e a Euroscore, respetivamente. Relativamente à existência de aterosclerose noutros territórios arteriais, 90,7% dos pacientes apresentaram ITB nos valores normais (≤0,9), 53,3% e 55,6% apresentaram espessura ≥1mm e placas carotídeas, respetivamente. Não se encontrou uma relação estatisticamente significativa entre o SCC e o ITB (p=0,22), EIM (p=0,33), FRS (p=0,25) e Euroscore (p=0,06). As escalas clássicas também não apresentaram correlação com o ITB e a EIM. No estudo retrospetivo a maioria dos participantes também era do sexo feminino (52,9%) e a idade média foi de 61,8±10,5 anos. Neste último não se verificou a ocorrência de nenhum evento major (Morte CV, EAM não fatal, AVC não fatal) ao fim de um ano de realização do Angio-TC.
Discussão: Apesar do presente estudo ter sido realizado em doentes sintomáticos referenciados para angio-TAC cardíaca (para esclarecimento da clínica), valores de score de cálcio coronário baixo associaram-se a uma elevada a uma considerável prevalência de atingimento vascular cerebrovascular e periférico. Embora não tivesse sido possível estabelecer uma correlação entre este score e as escalas clínicas de estratificação de risco, a prevalência dos factores de risco foi elevada e superior à que é descrita para a população portuguesa. Paralelamente, a identificação de cálcio coronário associou-se a uma maior taxa de prescrição de fármacos vasoprotectores, nomeadamente hipolipemiantes e hipotensores. Tratando-se de uma população com risco vascular à priori significativo, a taxa de eventos registados pela análise retrospetiva revelou-se muito baixa e inferior àquela que seria esperada para uma população com as mesmas características.
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Paiva, Fernando Fernandes. "Quantificação da perfusão sanguínea cerebral utilizando arterial spin labeling: aplicações em medidas de territórios vasculares e em imagens funcionais." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24082008-165710/.
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Arterial spin labeling é uma técnica completamente não invasiva que permite o monitoramento quantitativo da perfusão cerebral e, juntamente com outras técnicas de ressonância magnética, tem se estabelecido como uma excelente ferramenta para estudos relacionados à hemodinâmica e problemas vasculares cerebrais. Dentre as possíveis implementações da técnica, a abordagem contínua, combinada a uma bobina de marcação dedicada, apresenta algumas vantagens com relação à relação sinal-ruído e à deposição de potência de RF. No presente trabalho, estas vantagens foram exploradas na implementação de uma metodologia que permite a obtenção de mapas quantitativos de fluxo sanguíneo cerebral, bem como dos territórios vasculares das principais artérias suprindo o cérebro. Os resultados obtidos em humanos e animais revelam a robustez e aplicabilidade da técnica em estudos da hemodinâmica cerebral. Aplicações em hipertensão comprovam que a técnica é capaz de fornecer informações que podem auxiliar na compreensão de diferentes patologias. A implementação da variante dinâmica da técnica ASL demonstra a versatilidade da metodologia fornecendo ferramentas para uma maior compreensão das características espaciais e temporais da hemodinâmica cerebral. Os resultados demonstram isto tanto em condições de fluxo sanguíneo basal como em hiperemia causada por estímulos funcionais.Arterial spin labeling techniques allow to obtain quantitative maps of perfusion non-invasively. Along with other MRI techniques, it has proven useful for diagnosis of a variety of cerebrovascular diseases. Amongst the available basic implementations, the continuous approach employing a dedicated labeling RF coil has the advantages of presenting high signal-to-noise ratio and lower RF power deposition. In the present work, these advantages were explored in order to implement a methodology to obtain quantitative maps of cerebral blood flow and the vascular territories of the major cerebral feeding arteries. Human and animal results reveal the robustness and applicability of the technique in cerebral hemodynamic studies. Applications in hypertension show that the technique can provide complimentary information to improve the understanding of neurovascular diseases. The dynamic ASL technique shows the method versatility for studying the spatial and temporal characteristics of cerebral hemodynamics. The results unravel that both under basal and functional hyperemia conditions.
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Leoni, Renata Ferranti. "Avaliação da perfusão sanguínea cerebral em modelos animais de hipertensão utilizando Arterial Spin Labeling." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-04052012-150153/.
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A hipertensão arterial é uma doença que aflinge mais de um quarto da população adulta mundial e mais da metade da população idosa. Ela é o principal fator de risco para doenças cerebrovasculares e o segundo fator de risco, após idade, para os acidentes vasculares cerebrais (AVC) hemorrágico e isquêmico. É também a principal causa de declínio cognitivo e demência, incluindo a doença de Alzheimer. A hipertensão causa remodelamento vascular e modifica os mecanismos de regulação do fluxo sangüíneo cerebral, incluindo a hiperemia funcional, a autoregulação cerebrovascular e a regulação endotelial. Portanto, pesquisas contínuas sobre os efeitos da hipertensão na função cerebrovascular são cruciais para o desenvolvimento de terapias preventivas que objetivam minimizar os riscos de desenvolvimento de doenças cerebrovasculares. No presente estudo, a perfusão cerebral de um importante modelo experimental de hipertensão, o rato SHR (do inglês spontaneously hypertensive rat), foi avaliada utilizando as técnicas de arterial spin labeling (ASL), que permitem a quantificação não-invasiva da perfusão. Utilizando o método de ASL contínua, o fluxo sangüíneo cerebral foi quantificado para todo o cérebro do rato sob condições de normocapnia e hipercapnia. Resistência cerebrovascular aumentada e reatividade vascular ao CO2 reduzida foram observadas em SHR adultos, confirmando que a hipertensão leva à redução progressiva da capacidade de dilatação da vasculatura cerebral. A técnica de ASL dinâmica permitiu medir o fluxo sangüíneo cerebral funcional evocado por estimulação somatosensorial. Além de apresentarem resposta hemodinâmica positiva à estimulação, os ratos hipertensos também apresentaram resposta hemodinâmica negativa em áreas circundantes àquelas ativadas positivamente. Foi mostrado que esse resultado está relacionado com um efeito puramente hemodinâmico causado pela pressão arterial elevada e pela reserva vascular alterada do SHR. Experimentos farmacológicos mostraram diferenças na modulação do acoplamento neurovascular de SHR quando comparado com rato normotenso. Além disso, SHR submetidos à oclusão temporária da artéria cerebral média apresentaram maior volume da lesão isquêmica e do edema cerebral, redução severa da massa corporal e déficits neurológicos piores do que ratos normotensos. Esses resultados estão relacionados à autoregulação cerebral alterada e ao desenvolvimento prejudicado da circulação colateral em SHR. Em suma, os achados do presente estudo mostraram que a hipertensão resulta em reserva vascular prejudicada, acoplamento neurovascular alterado e piores conseqüências a um AVC isquêmico.Hypertension is a disease that afflicts more than a quarter of the general population and more than half of the elderly population. It is the most important modifiable risk factor for cerebrovascular diseases and the second most important risk factor, after age, for hemorrhagic and ischemic stroke. It is a leading cause of cognitive decline and dementia, including the Alzheimer\'s disease. Hypertension causes vascular remodeling and modifies the intricate mechanisms of cerebral blood flow (CBF) regulation, including functional hyperemia, cerebrovascular autoregulation, and endothelial regulation. For all of the above, continued research on the effects of hypertension on cerebrovascular function is a crucial step in the design of preventive therapies aimed at minimizing the risk of development of cerebrovascular disease. In the present work, cerebral perfusion of an important experimental model of hypertension, the spontaneously hypertensive rat (SHR), was evaluated using the arterial spin labeling (ASL) techniques, which allow non-invasive quantification of perfusion. Using continuous ASL, CBF was quantified for the whole rat brain under normocapnic and hypercapnic conditions. Increased cerebrovascular resistance and decreased vascular reactivity to CO2 were observed in adult SHR, confirming that hypertension leads to reduced compliance of the cerebral vasculature. The dynamic ASL technique allowed the measurement of functional CBF evoked by somatosensorial stimulation. Hypertensive rats not only showed positive hemodynamic response to stimulation, but also negative hemodynamic response in areas surrounding the positively activated areas. It was shown to be related to a purely hemodynamic effect caused by high blood pressure and impaired vascular reserve of the SHR. Pharmacological experiments showed differences on modulation of the neurovascular coupling in SHR when compared to normotensive rats. Moreover, hypertensive rats subjected to temporary middle cerebral artery occlusion had larger ischemic lesion volume and brain edema, severe decrease in body weight and worse neurological deficits, when compared to normotensive rats. These results are related to the altered cerebral autoregulation and impaired collateral circulation development in SHR. Taken together, the findings of the present work show that hypertension results in impaired vascular reserve, which is related to altered neurovascular coupling and worse stroke outcome.
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GUILHEM, RAYBAUT DOMINIQUE. "Accidents vasculaires cerebraux arteriels et ischemiques du sujet jeune." Nice, 1992. http://www.theses.fr/1992NICE6542.
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Wiersma, Jonna Alcide. "Measurement of cerebral blood flow in humans using MRI with arterial spin labelling." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.483504.
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Gonçalves, Helena Sofia dos Santos. "Estimulação magnética transcraniana repetitiva sobre o córtex esquerdo." Master's thesis, Universidade da Beira Interior, 2013. http://hdl.handle.net/10400.6/1517.
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Introdução: A estimulação magnética transcraniana repetitiva (EMTr) permite alterar a excitabilidade do tecido neuronal através da criação de campos magnéticos. A theta burst stimulation (TBS) é um protocolo de EMTr com duas variantes: TBS intermitente (iTBS-estimulação excitatória) e TBS contínua (cTBS - estimulação inibitória). Este estudo tem por objectivo averiguar se a TBS é capaz de produzir alterações na oxigenação cerebral, na pressão arterial e na frequência cardíaca quando aplicada ao córtex pré-frontal dorsolateral esquerdo em voluntários jovens e saudáveis.
Metodologia: A amostra inclui 79 voluntários, 30 dos quais submetidos a estimulação e 49 submetidos apenas à medição dos valores de oxigenação cerebral, todos entre os 18 e os 30 anos. Os 30 indivíduos estimulados foram divididos equitativamente em 3 grupos: cTBS, iTBS e placebo, tendo todos efectuado uma recolha dos valores de oxigenação cerebral, pressão arterial e frequência cardíaca, antes e depois da estimulação. Os indivíduos pertencentes ao grupo controlo da oxigenação cerebral fizeram apenas duas medições de oxigenação cerebral num intervalo de trinta minutos.
Resultados: Verificou-se que a estimulação inibitória (cTBS) produziu uma diminuição significativa (teste t de student, p=0,022) na oximetria do córtex esquerdo e marginalmente significativa na oximetria do córtex direito (teste t de student, p=0,068). No grupo excitatório (iTBS), para o córtex esquerdo, verificou-se que na fase “pós-TBS” a oximetria média foi significativamente superior à do grupo controlo (Dunnett, p=0,012) e que houve um aumento do valor médio da oxigenação na fase “pós-TBS” em relação á fase “pré-TBS”. Para as variáveis “pressão arterial” e “frequência cardíaca”, não se encontraram valores estatisticamente significativos.
Conclusões: Neste estudo concluiu-se que a cTBS aplicada ao córtex pré-frontal dorsolateral esquerdo, diminui a oxigenação do lobo frontal ipsilateral. Estes achados sugerem que a diminuição da actividade neuronal produzida pela cTBS poderá levar à diminuição do metabolismo, havendo uma menor necessidade de aporte de oxigénio à área estimulada. No grupo iTBS, a variação da média e os resultados do teste de Dunnett, levam-nos a supor que perante uma amostra maior teríamos obtido um aumento significativo da oxigenação na área estimulada. Concluiu-se ainda que numa população normal entre os 18 e os 30 anos, a variação de oxigenação num intervalo de 30 minutos não é estatisticamente significativa. Os resultados obtidos para as variáveis “frequência cardíaca” e “pressão arterial”, que não mostraram alterações em ambos os grupos cTBS e ITBS, ajudam a consolidar a segurança da técnica.Introduction: Repetitive transcranial magnetic stimulation (rTMS) can change the excitability of neuronal tissue through the induction of electromagnetic fields. Theta burst stimulation (TBS) is an rTMS protocol that has two variants: intermittent TBS (iTBS-excitatory) and continuous TBS (cTBS-inhibitory). This study aims to investigate whether TBS is able to produce changes in cerebral oxygenation, blood pressure and heart rate, when applied to the left dorsolateral prefrontal cortex (DLPFC) in healthy young volunteers. Materials & Methods: The sample includes 79 individuals, 30 of whom underwent stimulation and 49 that were submitted only to the measurement of cerebral oxygenation values, all between 18 and 30 years. The 30 stimulated individuals were divided equally into 3 stimulation groups: cTBS, iTBS and sham, all having made a collection of brain oxigenation, blood pressure and heart rate values before and after stimulation. The remaining individuals were allocated to the brain’s oxygenation control group in which only two measurements of oximetry were made, with an interval of thirty minutes. Results: It was found that inhibitory stimulation (cTBS) produced significantly lowered values in left’s brain oximetry (paired t-test, p=0,022) and marginally significant lower values for right brain oximetry (paired t-test, p=0,068). Regarding the iTBS, we noted that in the “afterstimulation” phase the left brain oximetry was significantly higher than in the control group (Dunnett, p=0,006) and there was an increase in the average value, from the “before” to the “after” phase. On the variables “heart rate” and “blood pressure” we found no significant changes. Conclusion: In this study we concluded that cTBS, when applied to the left dorsolateral prefrontal cortex, is able to lower brain´s oxygenation in the ipsilateral frontal lobe. These findings lead us to suggest that cTBS decreases neuronal activity and consequently its metabolism, leading to decreased oxygen delivery to the stimulated area. The iTBS group average variation and the Dunnett’s test result, leads us to believe that if we had a larger sample we could have a significant increase in stimulated area oxygenation. This study also revealed that in a normal population aged 18 to 30 years, variation of cerebral oxygenation within 30 minutes is not significant. The results of “heart rate” and “blood pressure” in individuals undergoing iTBS and cTBS help to consolidate technique security.
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RIGAUD, XAVIER. "Contribution a l'etude chez le sujet age du retentissement cerebral de l'hta et de ses traitements." Lille 2, 1990. http://www.theses.fr/1990LIL2M051.
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Sierra, Benito Cristina. "Alteraciones funcionales y estructurales precoces edn la circulación cerebral en la hipertensión arterial esencial." Doctoral thesis, Universitat de Barcelona, 2002. http://hdl.handle.net/10803/2160.
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HIPOTESIS DE TRABAJO Y OBJETIVOS: La hipertensión arterial (HTA), además de la edad, es el factor de riesgo que más se asocia a la presencia de lesiones cerebrales de sustancia blanca (LSB). De hecho, para la mayoría de autores, estas lesiones son consideradas como un marcador precoz de lesión cerebral en la HTA y relacionadas con el proceso arterioscleroso. No obstante, su etiopatogenia es compleja y supone la implicación de factores genéticos. La relación entre las LSB y los diferentes parámetros clínicos y biológicos asociados a la HTA no está suficientemente definida. Por otra parte, la mayoría de estudios realizados hasta la fecha se han efectuado en población anciana, o en un amplio rango de edades, o se han incluido pacientes hipertensos con tratamiento antihipertensivo, factores todos ellos que han podido actuar como factores de confusión. El objetivo del presente trabajo es determinar los posibles factores clínicos y biológicos relacionados con la presencia de LSB en pacientes asintomáticos de mediana edad afectos de hipertensión arterial esencial nunca tratada.METODOLOGIA: Se han incluido 66 pacientes hipertensos esenciales de ambos sexos, de edades comprendidas entre 50-60 años, nunca tratados, y sin evidencia de enfermedad cardiovascular. Los pacientes con diabetes mellitus y/o ingesta enólica >30 grs/día, y aquéllos con una estenosis carotídea >50% fueron excluidos del estudio. Se realizaron las siguientes exploraciones: MAPA de 24 horas, ecocardiograma, y determinación del genotipo del gen de la enzima de conversión de la angiotensina (ECA) mediante PCR. A todos los pacientes se les realizó una resonancia magnética cerebral (RM) y se les clasificó en dos grupos, en función de la presencia o ausencia de LSB.
RESULTADOS: Veintisiete (40.9%) pacientes hipertensos mostraban LSB en la RM. Los pacientes con LSB tenían unas cifras de presión arterial (PA) sistólica, diastólica, y presión de pulso, significativamente mayores que los pacientes hipertensos sin LSB, tanto en la clínica como en la MAPA. La presencia de hipertrofia del ventrículo izquierdo (HVI) en pacientes hipertensos con LSB era significativamente mayor que en hipertensos sin LSB (88.4% versus 58.3%; P=0.01). De la misma manera, la presencia de una HVI concéntrica era significativamente mayor (P=0.002) en pacientes con LSB (54%) que en hipertensos sin LSB (11%). El riesgo relativo de HVI concéntrica para la presencia de LSB, independiente de los valores de PA, fue de 8.22 (95% IC: 2.06-32.78). En referencia al estudio genético, se objetivó que los pacientes con LSB presentaban con mayor frecuencia, en comparación con los pacientes sin LSB, tanto el alelo D (74% versus 51.4%; P=0.014) como el genotipo DD (64% versus 28.6%; P=0.022) del gen de la ECA.
CONCLUSIONES: La presencia de LSB en pacientes hipertensos asintomáticos de mediana edad es un hallazgo frecuente y está relacionado con la severidad de la elevación de la PA. La existencia de estas lesiones está asociada a la presencia de una HVI concéntrica. De la misma manera, y de forma independiente de las cifras de PA, la presencia del genotipo DD del gen de la ECA podría ser un factor predisponente para el desarrollo de LSB en pacientes con hipertensión arterial esencial.
PRODUCCIÓN CIENTÍFICA:
- Sierra C, de la Sierra A, Mercader J, Gómez-Angelats E, Urbano-Márquez A, Coca A. "Silent cerebral white matter lesions in middle-aged essential hypertensive patients". J Hypertens 2002;20:519-524. FACTOR DE IMPACTO: 4.210
- Sierra C, de la Sierra A, Paré JC, Gómez-Angelats E, Coca A. "Correlation between silent cerebral white matter lesions and left ventricular mass and geometry in essential hypertension". Am J Hypertens 2002;15:507-512. FACTOR DE IMPACTO: 2.755
- Sierra C, Coca A, Gómez-Angelats E, Poch E, Sobrino J, de la Sierra A. "Renin-angiotensin system genetic polymorphisms and cerebral white lesions in essential hypertension". Hypertension 2002;39[part 2]:343-347. FACTOR DE IMPACTO: 5.364
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TANJI, PHILIPPE. "Traitement endovasculaire par cyanoacrylates des malformations arterio-veineuses cerebrales." Saint-Etienne, 1993. http://www.theses.fr/1993STET6407.
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FERRO, PATRICIA. "Dissections spontanees des arteres intracraniennees : a propos de 23 observations et revue de la litterature." Toulouse 3, 1994. http://www.theses.fr/1994TOU31527.
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Muela, Henrique Cotchi Simbo. "Avaliação da função cognitiva em pacientes com hipertensão arterial e sua correlação com as alterações da rigidez arterial e do fluxo cerebral." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-09032017-112813/.
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Introdução: A hipertensão arterial é uma doença crônica com alta prevalência na população e, se não tratada, está relacionada a complicações cardiovasculares graves incluindo insuficiência renal, doença arterial coronária e acidente vascular cerebral. A associação entre os valores de pressão arterial (PA) e o desempenho cognitivo, tanto em pessoas adultas hipertensas quanto normotensas também tem sido demonstrada, e a hipertensão arterial é um importante fator de risco para a ocorrência de demência vascular. No entanto, a relação entre a gravidade da hipertensão, suas alterações vasculares e o déficit cognitivo é pouco conhecida. Objetivo: avaliar as alterações de função cognitiva em pacientes com hipertensão arterial de diferentes estágios e suas correlações com as propriedades arteriais funcionais e estruturais avaliadas por métodos não invasivos e com a circulação cerebral avaliada pelo Doppler transcraniano. Métodos: Trata-se de um estudo transversal em pacientes com hipertensão arterial seguidos na unidade de hipertensão arterial do Incor e um grupo de controles normotensos. Os pacientes foram divididos em três grupos: normotensão, hipertensão estágio-1 e hipertensão estágio-2. Os pacientes foram submetidos aos seguintes procedimentos: avaliação da rigidez arterial pela medida da velocidade de onda de pulso, medida da espessura da íntima média das artérias carótidas e da pressão central não invasiva, avaliação do fluxo cerebral pelo Doppler transcraniano e testes para a avaliação da função cognitiva. Resultados: Foram incluídos 221 indivíduos (150 hipertensos e 71 normotensos) por um período de 24 meses. Comparado com os indivíduos normotensos, a disfunção cognitiva é mais frequente nos pacientes com hipertensão arterial e está diretamente relacionada com a gravidade da doença. Os pacientes com hipertensão tiveram maior rigidez arterial, menor resposta de vasorreatividade cerebral e pior desempenho cognitivo. Conclusão: As alterações da função cognitiva são mais frequentes nos pacientes com hipertensão arterial e se relacionaram com a gravidade da doença. Os pacientes hipertensos têm maiores alterações vasculares que se associaram com pior desempenho cognitivoIntroduction: Hypertension is a high prevalent chronic disease in the population and, if not treated, is related to severe cardiovascular complications including stroke, renal failure and coronary artery disease. The association between blood pressure (BP) values and cognitive performance both in hypertensive and normotensive adults have been shown and hypertension is an important risk factor for occurrence of vascular dementia. However, the relationship between the hypertension severity, their vascular changes and cognitive impairment is less studied. Objective: to evaluate the cognitive function changes in patients with hypertension at different stages and their correlations with functional and structural arterial proprieties changes evaluated by non-invasive methods and with cerebral blood flow evaluated by transcranial Doppler. Methods: It is cross-sectional study in patients with hypertension followed at the hypertension unit of the Heart Institute (Incor) and a control normotensive group. Patients were divided into three groups: normotension, hypertension stage-1 and hypertension stage-2. All patients were undergone to the following procedures: arterial stiffness evaluation by pulse wave velocity, intima media thickness measurement of the carotids arteries and the noninvasive central blood pressure, cerebral blood flow evaluated by Transcranial Doppler and tests for cognitive function evaluation. Results: There were included 221 individuals (150 hypertensives and 71 normotensives) during a period of 24 months. Compared to normotensive individuals, cognitive impairment is more frequent in patients with hypertension and it is proportionally greater with the hypertension severity. Patients with hypertension have greater vascular changes, lower cerebral vasoreactivity response and worse cognitive performance. Conclusion: Cognitive function changes are frequent in hypertensive patients and are related to the severity of the disease. Hypertensive patients have greater vascular changes that were associated to worse cognitive performance
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Ekelund, Anders. "Detection and haemodilutive treatment of cerebral arterial vasospasm and delayed ischaemia after aneurysmal subarachnoid haemorrhage." Lund : Lund University, 1999. http://catalog.hathitrust.org/api/volumes/oclc/68945106.html.
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Smith, Kurt Jason. "Effects of arterial blood gas concentrations on regional cerebral blood flow and metabolism during exercise." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54740.
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The magnitude of the cerebral blood flow (CBF) response to exercise is primarily related to the sensitive balance between arterial blood gases (partial pressure of arterial oxygen [PaO₂] and carbon dioxide [PaCO₂]) and cerebral metabolism. However, it has remained unclear whether experimentally or environmentally manipulating the oxygen tensions alters the regulatory influence of arterial blood gases on the intracranial velocities (CBV) and regional CBF responses to incremental exercise. The goal of the experimental chapters of this thesis (Chapter 4, 5 and 6) was to quantify the independent and combined influence of PaO₂ and PaCO₂ on global and regional CBV and CBF during exercise. Chapter 4 identified a heightened (nearly twice the expected response) posterior CBV response during hyperoxic (PO₂ ∼713 mmHg) compared to normoxic (PO₂ ∼160 mmHg) exercise. In contrast, both the anterior and posterior CBV responses were unaltered during mild hypoxic (PO₂ ∼121 mmHg) exercise compared to normoxic exercise. Chapter 5 demonstrated that during exercise in severe hypoxia (PO₂ ∼413 mmHg), following partial acclimatization to high altitude (5050 m), global CBF was elevated by ∼20% compared to sea-level exercise. The elevated global CBF during exercise at high altitude served to compensate for the hypoxemia, and in turn maintained cerebral oxygen delivery equivalent to sea-level values. Chapter 6 revisited and extended the observations during hyperoxic exercise from Chapter 4, whereby measures of extra-cranial CBF were compared with the intracranial velocities during normoxic and hyperoxic (PO₂ ∼300 mmHg) exercise, and also in a separate condition in which any exercise-induced rise in PaCO₂ was prevented (i.e., isocapnia was maintained). The differences observed between regional CBV and CBF during normoxic and hyperoxic incremental exercise trials were abolished when PaCO₂ was held constant. This final chapter also demonstrated that the increased ventilation, per se, is unlikely to influence the cerebrovascular response to exercise. In conclusion, changes in arterial blood gases (hypoxia and hyperoxia) can exacerbate the cerebrovascular response to exercise; however, during incremental exercise in hyperoxia, the regional differences, as well as the differential intracranial and extra-cranial flow responses, are mediated primarily by PaCO₂.Graduate Studies, College of (Okanagan)
Graduate
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BASTIE, SABATIE DELPHINE. "Interet de l'echographie transoesophagienne dans le bilan etiologique des accidents emboliques arteriels : a propos de 340 patients." Toulouse 3, 1994. http://www.theses.fr/1994TOU31516.
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Hérard, Alain. "L'arterite post-radique des vaisseaux a destinee cerebrale : etude de 12 cas." Angers, 1992. http://www.theses.fr/1992ANGE1034.
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Sortica, da Costa Cristine. "Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283240.
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Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants Brain injury in the preterm infant is associated with death and lifelong disability. Cerebral hypoxia and fluctuations in cerebral blood flow in the first two days of life have been implicated in the pathophysiology of haemorrhagic and ischaemic brain injury. Monitoring of haemodynamic changes during the early transitional circulation from in-utero to ex-utero life are currently based on standard measurements of systemic oxygenation and mean arterial blood pressure, with no reliable assessment of end-organ perfusion. In this thesis, measurements using near-infrared spectroscopy (NIRS) and functional echocardiography were made to assess cerebral perfusion and systemic blood flow in a cohort of preterm infants undergoing intensive care. This thesis is divided into four sections: i) The feasibility of continuous monitoring of cerebral oxygenation and cerebrovascular reactivity is demonstrated in a series of case reviews, and the association between cerebral oxygenation and cerebrovascular reactivity with outcome of brain injury and mortality is described. ii) Combining measurements of systemic blood flow with end organ perfusion was applied to define MABPOPT in preterm infants based on an index of cerebrovascular reactivity. Deviations below MABPOPT were associated with intraventricular haemorrhage and mortality. iii) The complexity of brain and systemic signals was studied by using multi-scale entropy analysis. Most studies using cerebral NIRS or systemic measurements of blood flow use linear analysis; however, a complex biological system, such as the human brain, includes many regulatory mechanisms that interact in a complex manner, resulting in effects that cannot be understood wholly through the analysis of its individual constituents. Lower complexity of brain signals was observed in infants who developed intraventricular hemorrhage or died. iv) Changes in systemic and cerebral oxygenation in a cohort of preterm infants in the first 48 hours of life was assessed using functional echocardiography. The patterns of changes in cardiac output and cerebral oxygenation in infants who did and did not have intraventricular haemorrhage are discussed. Furthermore, the relationship between the presence of a haemodynamically significant ductus arteriosus and brain injury is assessed.
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DELEAGE, UPI MARIE-HELENE. "Hemiplegie aigue acquise de l'enfant par ischemie arterielle cerebrale : a propos de 8 observations." Lyon 1, 1989. http://www.theses.fr/1989LYO1M091.
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Smirl, Jonathan David. "The relationship between arterial blood pressure and cerebral blood flow : insights into aging, altitude and exercise." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54000.
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The majority of previous research on the relationship between blood pressure and cerebral blood flow (CBF) through the application of transfer function analysis (TFA) has been performed under spontaneous conditions. Under these circumstances, there is little input signal power (blood pressure), which makes linear interpretation of the output (CBF) results tenuous. In five experimental studies, the general aim of this thesis was to provide new insights on the relationship(s) between blood pressure and CBF throughout the aging spectrum. The first study determined the reproducibility of TFA metrics during spontaneous and driven blood pressure oscillations. The results revealed that squat-stand maneuvers were the most robust and reliable method to evaluate this relationship throughout aging. Consequently, this methodology was employed for the research studies. The second study examined the pressure-flow response in younger adults with acutely elevated cerebrovascular resistance index (CVRi). Augmenting CVRi, even without changes in CO₂, resulted in increased phase lead and reduced amplitude modulation; therefore, the impact of CVRi needs to be considered for the parsimonious interpretation of TFA metrics. The third experiment examined the pressure-flow relationship in three adult populations: young and old healthy adults, and heart transplant recipients. Findings revealed comparable cerebral pressure-flow responses in all groups, despite elevated CVRi (older groups), and blunted cardiac baroreceptors (long-term heart transplant recipients). Thus, it appears the acutely increased phase and decreased gain noted in the second study may not accurately reflect the chronic elevations in CVRi in older adults.
Through the unique approach of oscillating blood pressure during exercise, the fourth study demonstrated that the cerebrovasculature high-pass filter model is intact in both young and older populations. The final study at high-altitude (5050m) explored the cerebral pressure-flow relationship prior to, during acclimatization, and return from high-altitude. Despite the marked oxygen desaturation, there were no changes to the pressure-flow response across the entire range of exposure acclimatization timelines. In conclusion: 1) squat-stand maneuvers provide a meritorious way to examine cerebral-pressure flow responses; and 2) effective pressure-flow relationships are maintained during healthy aging and exercise, and persist despite blunting of cardiac baroreflexes and reductions in arterial oxygen saturation.Graduate Studies, College of (Okanagan)
Graduate
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Austin, Nicola Cecile. "A study of the effect of the patent ductus arteriosus on the intracranial and extracranial arterial blood flow velocity waveforms in preterm infants." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296274.
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LEBLOND, DAVID. "Embolisation des anevrysmes arteriels cerebraux par coils : a propos de 23 observations." Lille 2, 1992. http://www.theses.fr/1992LIL2M151.
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Sugita, Kenichiro, Masato Shibuya, Masakazu Takayasu, Takahisa Kano, Yoshio Suzuki, and Shinichiro Tsugane. "Differing effects of vasopressin on regional cerebral blood flow of dogs following intracisternal vs. intra-arterial administration." Thesis, Elsevier, 1994. http://hdl.handle.net/2237/16721.
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Kwok, Chun Bun. "Cerebral blood flow measurement using intra-arterial bolus injection of ²H¦2O monitored with magnetic resonance spectroscopy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23622.pdf.
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Nascimento, Roberta Soares. "A hipertensão arterial e o acidente vascular cerebral como analisadores da atenção basica no SUS em Campinas." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309406.
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Orientador: Gastão Wagner de Sousa CamposTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: A Hipertensão Arterial (HA) e o Acidente Vascular Cerebral (AVC) como analisadores da atenção básica no SUS em Campinas. No Brasil o AVC é uma das primeiras causas de morte e importante fonte de incapacidade permanente entre adultos. Utilizaremos este agravo como analisador da atenção básica e sua relação com o diagnóstico e tratamento da HA. Descrevemos o perfil das vítimas de AVC e seu atendimento hospitalar no período de abril de 2006 a março de 2007. Descrevemos a ocorrência do agravo como indicador indireto de acesso de pacientes crônicos ao SUS, uma vez que o principal precursor do AVC é a HA que é um problema com prioridade de abordagem na rede básica. Analisamos narrativas produzidas a partir de grupos focais entre usuários e trabalhadores das Unidades Básicas de Saúde (UBS) sobre a amplitude de sua intervenção clínica. Consultamos as fichas familiares dos referidos pacientes na UBS e entrevistamos gerentes locais sobre a organização dos serviços. Agrupamos 06 UBS em três diferentes graus de implantação dos arranjos organizacionais e diretrizes do projeto Paidéia de saúde da Família, como o vínculo e adscrição de clientela por equipe de referência, a institucionalização do trabalho em equipe, atividades assistenciais coletivas e estratégias de intervenção no território. Analisamos as UBS com SUS dependência alta mas ao mesmo tempo com um grau de organização e cobertura assistencial maior ou igual a 50% Observamos a organização do processo de trabalho, agendas individuais, grupos, outras ações de promoção em saúde e atendimento domiciliar
Abstract: Arterial Hypertension and Cerebrovascular Accident as analyzers of primary care in the health care system in Campinas. In Brazil, the stroke is one of the leading causes of death and a major source of permanent disability among adults. We will use this harm as the primary analyzer of the basic attention and its relationship with diagnosis and treatment of hypertension. We describe the victims' profile of stroke and their hospital care from April 2006 to March 2007. We describe the occurrence of the disease as an indirect indicator of chronic patients' access to SUS since the main precursor of stroke is hypertension, which is a problem with priority in the basic approach. We analyzed narratives produced from focus groups among users and employees of the Basic Health Units (UBS) on the extent of their clinical intervention; consulted the records of those patients' family in the UBS and interviewed local managers on the organization of services. 06 UBS were grouped into three different degrees of implementation of organizational arrangements - Paideia Health Family Project's guidelines - as the bond and assignment of customers for reference team, the institutionalization of work, the teamwork, the collective welfare activities and the strategies of intervention on territory. We analyzed UBS with similar characteristics and with high dependence for the population by the Unified Health System (SUS) but, at the same time, with a degree of organization installed and welfare coverage greater than or equal to 50%. We observed the organization of the work process, individual agendas, educational groups on health and other actions to promote health and home care
Doutorado
Saude Coletiva
Doutor em Saude Coletiva
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Furlan, Natalia Eduarda [UNESP]. "Associação entre níveis de pressão arterial e letalidade na fase aguda do acidente vascular cerebral: estudo prospectivo." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/131897.
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000853911.pdf: 330429 bytes, checksum: b3fb9f15a4bd446ce94057a865231065 (MD5)Objetivo: Verificar a associação entre pressão arterial (PA) e letalidade do Acidente Vascular Cerebral (AVC), na fase aguda, em pacientes internados nas unidades de terapia intensiva (UTIs) de um hospital universitário. Métodos: Estudo observacional e prospectivo. Foram analisados pacientes com idade superior a 18 anos e de ambos os sexos, internados nas UTIs com diagnóstico de AVC hemorrágico e isquêmico. Foram excluídos os portadores de hemorragia subaracnóidea. Foram avaliados o índice APACHE II, a escala de Rankin modificada, a escala internacional de AVC do National Institute of Health (NIHSS) (NIH, 2009) e o valor da PA no momento da internação dos pacientes, bem como durante toda primeira semana, além de dados clínicos e laboratoriais. O desfecho primário foi o óbito, por todas as causas, nos primeiros sete dias e os secundários foram o óbito por causa neurológica e o óbito por causa não neurológica, no mesmo período. Resultados: Foram analisados 146 pacientes, a média de idade foi de 66,3± 13,4 anos, 56,1% dos pacientes foram do sexo masculino, a raça predominante foi a branca, em 89% dos analisados, a forma isquêmica da doença acometeu 69,1% dos pacientes. Dentre todos os pacientes 80,1% eram hipertensos e o valor médio do escore NIHSS foi de 16,4 ± 6,5 pontos. Pacientes que apresentaram PA, na admissão e nas primeiras 48 horas de internação, com valores abaixo de 140 mm Hg apresentaram maior chance de óbito. Essa associação foi observada apenas quanto ao óbito de origem não neurológica, bem como apresentou significância estatística marginal na análise múltipla, com ajuste para o NIHSS, tipo de AVC, maior variabilidade da PA, variabilidade da glicemia, realização de trombólise, ocorrência de infecção e creatinina. Já a variabilidade da PA, apresentou associação estatisticamente significante com o desfecho primário, independente dos fatores de confusão avaliados. Conclusão: Houve...
Objective: Investigating the association between blood pressure (BP) and lethality in stroke in the acute phase, in patients in intensive care units (ICU) of a university hospital. Methods: It is a prospective trial. This study has analyzed patients older than 18 years and of both sexes, admitted in the ICU with a diagnosis of hemorrhagic and ischemic stroke. It has excluded patients with subarachnoid hemorrhage. We have evaluated the APACHE II index, the modified Rankin scale, the international scale of the accident stroke of the National Institute of Health (NIHSS) (NIH, 2009) and the value of BP at admission of patients, as well during their first week, clinical and laboratory data. The primary outcome was death, from all causes, in the first seven days and the secondary endpoints were death from neurological and non-neurological causes during the same period. Results: The study analyzed 146 patients, the average age was 66.3 ± 13,4 years, 56.1% of patients were male, the predominant race was the white, in 89% of analyzed, ischemic form of the disease affected 69 1% of patients. Among all patients 80.1% were hypertensive and the average value of NIHSS score was 16.4 ± 6,5 points. Patients with PA, on arrival and in the first 48 hours of admission, with values below 140 mm Hg had higher chance of death. This association was observed only on the non-neurological origin of death, and it showed marginal statistical significance in the multivariate analysis, adjusted for NIHSS, type of stroke, BP variability, variability of blood glucose, thrombolysis, occurrence of infection and creatinine. Since the BP variability, showed a statistically significant association with the primary outcome, independent of confounders evaluated. Conclusion: There was a negative association between PA and mortality of stroke in the acute phase in patients in intensive care units. This association was present only for ...
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Furlan, Natalia Eduarda. "Associação entre níveis de pressão arterial e letalidade na fase aguda do acidente vascular cerebral : estudo prospectivo /." Botucatu, 2015. http://hdl.handle.net/11449/131897.
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Orientador: Luis Cuadrado MartinCoorientador: Rodrigo Bazan
Banca: Luiz Eduardo Gomes Garcia Betting
Banca: Márcia de Fátima Faraldo Nartinez Garcia
Resumo: Objetivo: Verificar a associação entre pressão arterial (PA) e letalidade do Acidente Vascular Cerebral (AVC), na fase aguda, em pacientes internados nas unidades de terapia intensiva (UTIs) de um hospital universitário. Métodos: Estudo observacional e prospectivo. Foram analisados pacientes com idade superior a 18 anos e de ambos os sexos, internados nas UTIs com diagnóstico de AVC hemorrágico e isquêmico. Foram excluídos os portadores de hemorragia subaracnóidea. Foram avaliados o índice APACHE II, a escala de Rankin modificada, a escala internacional de AVC do National Institute of Health (NIHSS) (NIH, 2009) e o valor da PA no momento da internação dos pacientes, bem como durante toda primeira semana, além de dados clínicos e laboratoriais. O desfecho primário foi o óbito, por todas as causas, nos primeiros sete dias e os secundários foram o óbito por causa neurológica e o óbito por causa não neurológica, no mesmo período. Resultados: Foram analisados 146 pacientes, a média de idade foi de 66,3± 13,4 anos, 56,1% dos pacientes foram do sexo masculino, a raça predominante foi a branca, em 89% dos analisados, a forma isquêmica da doença acometeu 69,1% dos pacientes. Dentre todos os pacientes 80,1% eram hipertensos e o valor médio do escore NIHSS foi de 16,4 ± 6,5 pontos. Pacientes que apresentaram PA, na admissão e nas primeiras 48 horas de internação, com valores abaixo de 140 mm Hg apresentaram maior chance de óbito. Essa associação foi observada apenas quanto ao óbito de origem não neurológica, bem como apresentou significância estatística marginal na análise múltipla, com ajuste para o NIHSS, tipo de AVC, maior variabilidade da PA, variabilidade da glicemia, realização de trombólise, ocorrência de infecção e creatinina. Já a variabilidade da PA, apresentou associação estatisticamente significante com o desfecho primário, independente dos fatores de confusão avaliados. Conclusão: Houve...
Abstract: Objective: Investigating the association between blood pressure (BP) and lethality in stroke in the acute phase, in patients in intensive care units (ICU) of a university hospital. Methods: It is a prospective trial. This study has analyzed patients older than 18 years and of both sexes, admitted in the ICU with a diagnosis of hemorrhagic and ischemic stroke. It has excluded patients with subarachnoid hemorrhage. We have evaluated the APACHE II index, the modified Rankin scale, the international scale of the accident stroke of the National Institute of Health (NIHSS) (NIH, 2009) and the value of BP at admission of patients, as well during their first week, clinical and laboratory data. The primary outcome was death, from all causes, in the first seven days and the secondary endpoints were death from neurological and non-neurological causes during the same period. Results: The study analyzed 146 patients, the average age was 66.3 ± 13,4 years, 56.1% of patients were male, the predominant race was the white, in 89% of analyzed, ischemic form of the disease affected 69 1% of patients. Among all patients 80.1% were hypertensive and the average value of NIHSS score was 16.4 ± 6,5 points. Patients with PA, on arrival and in the first 48 hours of admission, with values below 140 mm Hg had higher chance of death. This association was observed only on the non-neurological origin of death, and it showed marginal statistical significance in the multivariate analysis, adjusted for NIHSS, type of stroke, BP variability, variability of blood glucose, thrombolysis, occurrence of infection and creatinine. Since the BP variability, showed a statistically significant association with the primary outcome, independent of confounders evaluated. Conclusion: There was a negative association between PA and mortality of stroke in the acute phase in patients in intensive care units. This association was present only for ...
Mestre
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Awad, Mohammad Ahmad. "Assessment of Pseudo-Continuous Arterial Spin Labeling (pCASL) Inter-Session Reliability in the Quantification of Cerebral Perfusion." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright156052676971687.
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NUSSBAUM, PIERRE. "Asystolie du nourrisson par fistule arterio-veineuse cerebrale peripherique : interet de l'echo doppler couleur." Lille 2, 1990. http://www.theses.fr/1990LIL2M323.
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FRANCILLOTTI, AGNES. "Les anevrismes arterio-veineux cerebraux et medullaires : a propos de 50 cas." Aix-Marseille 2, 1988. http://www.theses.fr/1988AIX20447.
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Menon, Rajiv G. "Regional cerebral blood flow (RCBF) calculations in awake, behaving non-human primates using continuous arterial spin labeling (CASL) techniques." Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2008r/menon.pdf.
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Mačiulevičienė, Regina. "Vaisiaus kraujotakos tyrimų vertė blužnies ir vidurinėje smegenų arterijose rezus izoimunizacijos atvejais." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20060202_153259-36891.
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ABBREVIATIONS
A – amniocentesis
DA – deceleration angle
FMH – fetomaternal haemorrhage
MCA – middle cerebral artery
MoM – multiples of median
PI – pulsatility index
PSV – peak systolic velocity
RI – resistance index
SA – splenic artery
SGA – small for gestational age
HDN – haemolytic disease of newborn
1. INTRODUCTION
Rhesus alloimmunization occurs when a rhesus negative woman has an immunologic response to a paternally derived red-cell antigen that is foreign to the mother and inherited by the fetus. Rhesus alloimmunization and haemolytic disease of the newborn continues to occur as a serious complication of pregnancy despite well-organized antenatal antiD prophylaxis programs. At the Perinatal Center of Kaunas University
of Medicine the incidence has remained stable at around 60 cases of alloimmunized pregnancies and from 30 to 40 cases of haemolytic disease of newborn annually. Perinatal mortality in cases of rhesus alloimmunization has been estimated to be at around 1 to 3.5 percent. Due to failure to apply or comply with antiD prophylaxis guidelines and limitations of the prophylaxis rhesus sensitization continues to occur.
Rhesus alloimmunization is diagnosed when the test of a rhesus negative woman for red cell alloantibodies is positive. Prognosis for the fetus and perinatal outcomes depends much on how severely the fetus is affected by the disease at the time of diagnosis. The main pathological entity of the disease is fetal red blood cell destruction and... [to full text]