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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
681

Atrial Fibrillation in the setting of Coronary Artery Disease : Risks and outcomes with different treatment options

Batra, Gorav January 2017 (has links)
Coronary artery disease (CAD) is the leading cause of mortality worldwide and atrial fibrillation (AF) is a prevalent arrhythmia associated with increased risk of mortality and morbidity. Despite improved outcome in both diseases, there is a need to further describe the prevalence, outcome and management of CAD in patients with concomitant AF. AF was a common finding among patients with MI, with 16% having new-onset, paroxysmal or chronic AF. Patients post-MI with concomitant AF, regardless of subtype, were at increased risk of composite cardiovascular outcome of mortality, MI or ischemic stroke, including mortality and ischemic stroke alone. No major difference in outcome was observed between AF subtypes. At discharge, an oral anticoagulant was prescribed to 27% of the patients with MI and AF undergoing percutaneous coronary intervention (PCI). Aspirin or clopidogrel plus warfarin versus dual antiplatelet therapy with aspirin plus clopidogrel were associated with similar 0-90-day and lower 91-365-day risk of cardiovascular outcome, without increased risk of major bleeding events. Triple therapy with aspirin, clopidogrel plus warfarin versus dual antiplatelet therapy was associated with non-significant lower risk of cardiovascular outcome, but with increased risk of bleeding events. Treatment with renin-angiotensin system (RAS) inhibitors post-MI was associated with lower risk of all-cause and cardiovascular mortality in patients with and without congestive heart failure and/or AF. However, RAS inhibition in patients without AF was not associated with lower risk of new-onset AF. Approximately 1 in 3 patients undergoing isolated coronary artery bypass grafting (CABG) had pre- or postoperative AF. Patients with AF, regardless of subtype, were at higher risk of all-cause mortality, cardiovascular mortality and congestive heart failure. Furthermore, postoperative AF was associated with higher risk of recurrent AF. In conclusion, AF was a common finding in the setting of MI and CABG. AF, irrespectively if in the setting of MI or CABG was associated with higher risk of ischemic events and mortality. Also, postoperative AF was associated with recurrent AF. Oral anticoagulants post-MI and PCI in patients with AF was underutilized, however, optimal antithrombotic therapy is still unknown. RAS inhibition post-MI seems beneficial, however, it was not associated with lower incidence of new-onset AF.
682

Randomisierter Vergleich von Medikamenten freisetzenden Stents mit minimal-invasiver Bypasschirurgie für isolierte proximale LAD-Stenosen – Ein 7-Jahres-Follow-Up

Rossbach, Cornelius 22 March 2017 (has links) (PDF)
OBJECTIVES The aim of this analysis was to assess the 7-year long-term safety and effectiveness of a randomized comparison of percutaneous coronary intervention (PCI) with sirolimus-eluting stents (SES) versus minimally invasive direct coronary artery bypass (MIDCAB) surgery for the treatment of isolated proximal left anterior descending lesions. BACKGROUND Long-term follow-up data comparing PCI by SES and MIDCAB surgery for isolated proximal left anterior descending lesions are sparse. METHODS Patients were randomized either to PCI with SES (n ¼ 65) or MIDCAB (n ¼ 65). Follow-up data were obtained after 7 years with respect to the primary composite endpoint of death, myocardial infarction, and target vessel revas- cularization. Angina was assessed by the Canadian Cardiovascular Society classification and quality of life with Short Form 36 and MacNew quality of life questionnaires. RESULTS Follow-up was conducted in 129 patients at a median time of 7.3 years (interquartile range: 5.7, 8.3). There were no significant differences in the incidence of the primary composite endpoint between groups (22% PCI vs. 12% MIDCAB; p ¼ 0.17) or the endpoints death (14% vs. 17%; p ¼ 0.81) and myocardial infarction (6% vs. 9%, p ¼ 0.74). However, the target vessel revascularization rate was higher in the PCI group (20% vs. 1.5%; p < 0.001). Clinical symptoms and quality of life improved significantly from baseline with both interventions and were similar in magnitude between groups. CONCLUSIONS At 7-year follow-up, PCI by SES and MIDCAB in isolated proximal left anterior descending lesions yielded similar long-term outcomes regarding the primary composite clinical endpoint and quality of life. Target vessel revascularization was more frequent in the PCI group. (Randomied Comparison of Minimally Invasive Direct Coronary Artery Bypass Grafting and Percutaneous Coronary Intervention With Drug-Eluting Stents in Patients With Proximal Stenosis of the Left Anterior Descending Coronary Artery; NCT00299429) (J Am Coll Cardiol Intv 2014;-:-–-) © 2014 by the American College of Cardiology Foundation.
683

Estudo da maturação da resposta vascular da artéria mesentérica superior em recém-nascidos prematuros através do dopplerfluxometria / Evolution of superior mesenteric artery blood flow by means of doppler velocimetry in health premature neonates

Chia, Chang Yin 16 April 2009 (has links)
INTRODUÇÃO: O conhecimento de valores de normalidade do fluxo sanguíneo da artéria mesentérica superior (AMS) em recém-nascidos prematuros (RNPT) saudáveis pode prevenir quadros de intolerância alimentar e a ocorrência da enterocolite necrosante. MÉTODOS: Com o objetivo de descrever a evolução dos índices de avaliação da dopplerfluxometria da AMS em RNPT saudáveis de idade gestacional entre 27 e 34 semanas completas, no primeiro, no terceiro, no sétimo e semanalmente (14, 21, 28, 35 e 42 dias de vida), foi realizado este estudo coorte prospectivo em RNPT de idade gestacional ao nascimento entre 27 e 34 semanas completas. O exame dopplerfluxométrico foi realizado, após o consentimento livre e esclarecido dos responsáveis pelos RNPT, através do aparelho Logic Book 8C-RS (General Eletric EUA); obtendo-se as seguintes medidas: pico de velocidade sistólica (PVS), pico de velocidade diastólica final (PVDF) e média de velocidade de fluxo; sendo, após, calculadas o Índice de Pourcelot, sendo: [pico de velocidade sistólico pico diastólico final] / pico de velocidade sistólico, que representa um índice de resistência (IR); e índice de pulsatilidade (IP). Foram excluídos: recém-nascidos com instabilidade hemodinâmica; em ventilação assistida com altos parâmetros; síndromes mal-formativas; intolerância alimentar ou enterocolite necrosante; fototerapia; presença de cateteres umbilicais, persistência de canal arterial e pequenos para a idade gestacional. O exame pré-prandial foi realizado antes da alimentação (até 30 minutos) e pós-prandial entre 15 e 60 minutos após a alimentação. Foram realizados no primeiro dia (entre 6 a 24 horas de vida), no terceiro, no sétimo, e após, semanalmente até 42 dias de vida. Os resultados foram expressos em médias e desvios-padrão e descritos de maneira evolutiva. RESULTADOS: Ao total, foram estudados 77 RNPT e realizados 125 exames. Os valores em média±desvio-padrão são descritos na seqüência do primeiro, terceiro, sétimo e, consecutivamente a cada semana, até 42 dias de vida; sendo: IR pré-prandial de 0,69±0,09; 0,67±0,15; 0,75±0,07; 0,74±0,07; 0,75±0,07; 0,76±0,07; 0,79±0,03; 0,78±0,05 e IR pós-prandial de 0,66±0,10; 0,70±0,21; 0,74±0,07; 0,73±0,08; 0,75±0,06; 0,76±0,06; 0,77±0,04; 0,77±0,03. Os resultados de IP pré-prandial foram: 1,45±0,30; 1,35±0,28; 1,68±0,29; 1,50±0,23; 1,47±0,22; 1,52±0,20; 1,62±0,09; 1,68±0,06 e IP pós-prandial: 1,38±0,39; 1,40±0,29; 1,58±0,26; 1,46±0,26; 1,45±0,24; 1,50±0,27; 1,58±0,10; 1,64±0,04. Obtivemos PVS pré-prandial: 60,51±22,24; 55,24±26,04; 90,61±12,74; 95,33±18,11; 92,89±15,40; 96,96±12,18; 63,18±14,08; 58,12±9,78 e pós-prandial: 59,60±24,14; 110,82±32,45; 118,10±20,15; 121,95±24,18; 124,15±25,16; 126,07±18,17; 96,68±11,12; 96,12±8,98. Quanto a PVDF pré-prandial, obtivemos: 18,85±6,09; 18,66±10,01; 20,99±8,12; 22,02±8,50; 23,04±7,89; 22,24±8,02; 11,99±6,15; 12,05±5,12 e PVDF pós-prandial: 20,63±6,89; 30,15±12,78; 27,98±9,72; 29,02±10,05; 34,56±9,00; 32,02±8,45; 19,02±4,95; 21,15±3,43. A partir dos resultados acima, demonstra-se que o fluxo sanguíneo da AMS em RNPT saudáveis apresenta uma evolução peculiar a partir do nascimento tanto dos valores basais quanto após a estimulação com a dieta, representados por uma evolução característica dos índices de resistência, melhora dos picos de velocidades sistólica e diastólica e melhora da resposta vasodilatadora após a alimentação enteral. CONCLUSÕES: RNPT saudáveis de idade gestacional ao nascimento de 27 a 34 semanas completas apresentam uma evolução do fluxo sanguíneo da artéria mesentérica superior de maneira peculiar, do nascimento até 42 dias de vida, tanto dos valores basais quanto em resposta à alimentação. O conhecimento destes valores pode indicar a dopplerfluxometria como um método preventivo de avaliação específico de cada RNPT para a introdução e progressão mais segura da alimentação, reduzindo a ocorrência de quadros gastrintestinais, melhorando os índices de morbi-mortalidade neonatal. / INTRODUCTION: The knowledge of the normal values of indices of Doppler velocimetry of the superior mesenteric artery in healthy premature neonates may help to prevent feeding intolerance situations and necrotizing enterocolitis. METHODS: In order to describe the indices for evaluation of Doppler velocimetry of the superior mesenteric artery in healthy premature neonates with gestational age between 27 and 34 weeks, on the first, third, seventh days, and then weekly, until six weeks of life; this is a prospective cohort study. The Doppler velocimetric examination was done by means of the Logic Book 8C-RS (General Electric USA), using a 8 MHz imaging transducer, with the pulsed color Doppler readings being obtained by sonographic waves at 4 MHz. The neonate was kept in a supine position, with the transducer positioned in the epigastric region, immediately below the xyphoid appendix, obtaining two-dimensional images of the celiac trunk and of the superior mesenteric artery, a few millimeters after its emergence from the aorta in the sagittal plane. The flux measurements were obtained in the longitudinal direction of the vessel and at an angle of insonation between 0 and 20 degrees. The blood flow curves were recorded after a sequence of five stable measurements, with respect to the quality of the waves, and with respect to their audible characteristics; thus obtaining the following measurements: peak systolic velocity (PSV), end diastolic velocity (EDV) and average flow velocity; with the Pourcelot Index being calculated subsequently, that is: [peak of systolic velocity end diastolic velocity / peak of systolic velocity, which represents a resitance index (RI); and pulsatility index (PI). The values obtained were expressed as averages and standard deviations. The results were stored in an Excel database, with blind analysis after the conclusion of data gathering. Uncomplicated and appropriate for gestational age premature neonates with gestational age between 27 and 34 weeks at birth were included in the study. We adopted as criteria for exclusion from the study: neonates in unstable hemodynamic conditions; needing assisted ventilation with high parameters; large deformations or clinical syndromes; feeding intolerance or diagnosis of necrotizing enterocolitis; conditions that alter the mesenteric flow, such as: phototherapy, presence of umbilical catheters, patent ductus arteriosus and sepsis. The exams were done prior to feeding (up to 30 minutes) and after feeding (between 15 and 60 minutes). If the neonate was fasting, only one of the above parameters was measured, in order to establish behavior of the basal mesenteric flow at that moment. The exams were done on the first day (between the 6th and 24th hours of life), third, seventh days, and then weekly, until six weeks of life. Data are shown as the mean ± standard deviation and described for each postnatal age group. RESULTS: A total of 77 neonates were studied and realized 125 exams. The values of the resistance and pulsatility indices (RI and PI); peaks of systolic (PSV) and final diastolic velocity (EDV) on the first, third, seventh days, and then, on sequentially for each week until six weeks of postnatal life; as mean and standard deviations, was described: RI prior to feeding were 0,69±0,09; 0,67±0,15; 0,75±0,07; 0,74±0,07; 0,75±0,07; 0,76±0,07; 0,79±0,03; 0,78±0,05 and RI after feeding were 0,66±0,10; 0,70±0,21; 0,74±0,07; 0,73±0,08; 0,75±0,06; 0,76±0,06; 0,77±0,04; 0,77±0,03. The results of PI prior to feeding: 1,45±0,30; 1,35±0,28; 1,68±0,29; 1,50±0,23; 1,47±0,22; 1,52±0,20; 1,62±0,09; 1,68±0,06 and PI after feeding: 1,38±0,39; 1,40±0,29; 1,58±0,26; 1,46±0,26; 1,45±0,24; 1,50±0,27; 1,58±0,10; 1,64±0,04. The values of PSV prior to feeding were: 60,51±22,24; 55,24±26,04; 90,61±12,74; 95,33±18,11; 92,89±15,40; 96,96±12,18; 63,18±14,08; 58,12±9,78 and after feeding: 59,60±24,14; 110,82±32,45; 118,10±20,15; 121,95±24,18; 124,15±25,16; 126,07±18,17; 96,68±11,12; 96,12±8,98. And the results of EDV prior to feeding: 18,85±6,09; 18,66±10,01; 20,99±8,12; 22,02±8,50; 23,04±7,89; 22,24±8,02; 11,99±6,15; 12,05±5,12 and EDV after feeding: 20,63±6,89; 30,15±12,78; 27,98±9,72; 29,02±10,05; 34,56±9,00; 32,02±8,45; 19,02±4,95; 21,15±3,43. These results shows that healthy premature neonates with gestational age between 27 and 34 weeks presents a peculiar evolution in blood flow in the superior mesenteric artery after birth, represented by the resistance patterns caracteristics, improvement in peaks of systolic and diastolic velocity, and improvement in vasodilation in response to feeding. CONCLUSION: These results suggest for the Doppler velocimetry as specific and preventive evaluation method for each premature neonate, as a way to a safer introduction and progression of feeding, reducing the prevalence of gastrointestinal inflammatory diseases in neonates, and improving the indices of neonatal morbidity and mortality. Knowledge of blood-flow velocity in the superior mesenteric artery in uncomplicated preterm infants might provide a clue in investigating the maturation of intestinal circulation and the pathogenesis or pathophysiology of gastrointestinal diseases in newborn infants.
684

Métodos para quantificação da artéria carótida em imagens de ultrassom modo-B e Doppler. / Methods for quantification of the carotid artery in B-mode and Doppler ultrasound images.

Higa, Mauricio 27 November 2009 (has links)
No campo da medicina diagnóstica através de imagens, o baixo custo e a característica não-invasiva da ultrassonografia modo-B favoreceram as pesquisas que analisam a relação entre a espessura íntima-média (EIM) da artéria carótida e o desenvolvimento de doenças cardiovasculares. Outra técnica de ultrassonografia, baseada no efeito Doppler, também tem sido extensivamente empregada em ambientes clínicos para a medição da velocidade e do fluxo de sangue das artérias periféricas, oferecendo uma abordagem distinta para estudar as doenças cardiovasculares. Neste trabalho, métodos computacionais foram implementados e analisados para extrair informações quantitativas de artérias a partir de imagens 2D. Os ensaios com imagens em modo-B contemplaram a combinação de técnicas de filtragem e algoritmos de contornos ativos para a detecção das interfaces das paredes arteriais e medições da EIM e do diâmetro da luz (DL). Um modelo matemático e 7 imagens reais da artéria carótida comum foram utilizados neste estudo que, dentre as diversas combinações de filtros e algoritmos, apresentou resultados quantitativos similares no cálculo do DL. Para a EIM, porém, a reduzida dimensão da camada íntima-média proporcionou variações indesejadas dos cálculos. Para medir a velocidade do sangue utilizando o modo Doppler, um método semiautomático foi incorporado a um aplicativo computacional para a detecção da envoltória do espectro do gráfico de velocidades. Uma análise comparativa entre sistemas de ultrassonografia comerciais operados por especialistas e este aplicativo incluiu a velocidade de pico sistólico e a integral de velocidade e tempo (VTI) das artérias carótida comum e braquial e de exames ecocardiográficos. A análise de Bland-Altman e o coeficiente de correlação validaram esta metodologia que, complementada pela interface gráfica amigável do aplicativo, pode auxiliar os clínicos em seus estudos de larga escala, baseados nas imagens Doppler ultrassonográficas, com as seguintes vantagens: redução do tempo operacional e de resultados subjetivos e aumento do grau de reprodutibilidade dos resultados. / In the field of image-based diagnostic medicine, low cost and noninvasive B-mode ultrasound technique have supported the researches which investigates the relation between the carotid intima-media thickness (IMT) and the development of cardiovascular diseases. Other ultrasound technique, that offers a different approach to study these diseases, is based on Doppler effect and has also been extensively used in clinical sites to measure blood velocity and flow in peripheral arteries. In this work, computational methods were implemented and analyzed to extract quantitative data from 2D images of arteries. Tests with B-mode images covered the combination of filtering techniques and active contour algorithms, in order to detect the arterial wall interfaces and to measure IMT and lumen diameter (LD). One mathematical model and seven real images of the common carotid artery were used in this study which, among several filters and algorithms combinations, showed similar quantitative results for DL measurements. However, for IMT, the small thickness of intima-media layer led to undesirable variation results. To measure blood velocity by using Doppler mode, a semi-automatic methodology was implemented in a computational tool to detect the spectrum envelope of the velocity graphic. A comparative analysis between commercial ultrasound systems operated by specialists and this tool included systolic peak velocities and velocity-time integral (VTI) of the common carotid and brachial arteries and of echocardiographic exams. Bland-Altmans analysis and the correlation coefficient validated this methodology which, besides the user friendly graphical interface of the tool, may help the clinicians for their large-scale studies based on Doppler ultrasound images, with the following advantages: to save operational time, to lower subjective results, and to support measurement reproducibility.
685

Liberação de biomarcadores de necrose miocárdica após revascularização cirúrgica do miocárdio sem circulação extracorpórea, em ausência de infarto do miocárdio manifesto, avaliado pela ressonância magnética cardíaca / Biomarker release after coronary artery bypass grafting in patients without definitive myocardial infarction assessed by cardiac magnetic resonance with late gadolinium enhancement

Costa, Leandro Menezes Alves da 15 May 2017 (has links)
Introdução: A liberação de biomarcadores de necrose miocárdica após revascularização miocárdica cirúrgica (RM) ocorre com frequência. No entanto, a correlação entre a liberação de biomarcadores e o diagnóstico do infarto agudo do miocárdio (IAM) periprocedimento gera controvérsias, especialmente com o aumento da sensibilidade nos ensaios de troponina (Tn). Neste estudo, objetivou-se quantificar a liberação dos biomarcadores cardíacos em pacientes submetidos à RM, sem o uso de circulação extra corpórea (CEC), que não apresentaram evidências de infarto do miocárdio por meio da avaliação do realce tardio pelo gadolínio (RTG) na ressonância magnética cardíaca (RMC). Métodos: Pacientes portadores de doença arterial coronária estável e função ventricular preservada, com indicação eletiva para RM sem CEC, foram incluídos. RMC com RTG foi realizada em todos os pacientes antes e depois do procedimento. Aferições seriadas de Tn e creatinoquinase fração MB (CK-MB) foram realizadas antes do procedimento e até 72h após. Pacientes com RTG na RMC após o procedimento foram excluídos. Resultados: 73 pacientes foram referenciados para a realização eletiva da RM sem CEC e 20 (27%) foram excluídos, 14 (19%) por causa do surgimento de um novo RTG na RMC. Dentre os 53 pacientes sem evidência de IAM periprocedimento pela RMC, 37 (70%) eram do gênero masculino, a média da idade foi 63 (± 10) anos e o escore SYNTAX médio encontrado foi 20 (±7). Após a RM, todos os pacientes apresentaram um pico de elevação de Tn acima do percentil 99; em 48 (91%) pacientes a elevação foi superior a 10 vezes esse limite. Por outro lado, 41 (76%) pacientes apresentaram pico de CK-MB acima do percentil 99 e em apenas 7 (13%) este pico foi superior à10 vezes o percentil 99. A mediana do pico de liberação da Tn foi 2,0 (0,8 - 3,7) ng/mL, valor 50 vezes superior ao percentil 99. Conclusão: Diferente da CK-MB, a liberação da troponina I ocorre, frequentemente, após procedimento de RM sem CEC na ausência de realce tardio pela RMC / Background: The release of myocardial necrosis biomarkers after off-pump coronary artery bypass grafting (OPCAB) frequently occurs. However, the correlation between biomarker release and the diagnosis of procedurerelated myocardial infarction (MI) (type 5) has been controversial. This study aims to evaluate the amount and pattern of cardiac biomarker release after elective OPCAB in patients without the image of a new MI assessed by cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE). Methods: Patients with normal baseline cardiac biomarkers referred for elective OPCAB were prospectively included. CMR with LGE was performed in all patients before and after interventions. Measurements of troponin I (cTnI) and creatinekinase MB fraction (CK-MB) were systematically performed before and after the procedure. Patients with a new LGE on the post-procedure CMR were excluded. Results: Of the 53 patients without the evidence of a procedure-related MI assessed by the CMR after OPCAB, all patients exhibited cTnI elevation peak above the 99th percentile. In 48 (91%), the peak value was greater than 10 times this threshold. However, 41 (76%) had CK-MB peak above the limit of the 99th percentile, and this peak was greater than 10 times the 99th percentile in only 7 patients (13%). The median peak release of cTnI was 0.20 (0.8 - 3.7) ng/mL, which is 50-fold higher than the 99th percentile. Conclusions: In contrast to CK-MB, cTnI release often occurs after an elective OPCAB procedure, despite the absence of a new LGE on CMR
686

Métodos para quantificação da artéria carótida em imagens de ultrassom modo-B e Doppler. / Methods for quantification of the carotid artery in B-mode and Doppler ultrasound images.

Mauricio Higa 27 November 2009 (has links)
No campo da medicina diagnóstica através de imagens, o baixo custo e a característica não-invasiva da ultrassonografia modo-B favoreceram as pesquisas que analisam a relação entre a espessura íntima-média (EIM) da artéria carótida e o desenvolvimento de doenças cardiovasculares. Outra técnica de ultrassonografia, baseada no efeito Doppler, também tem sido extensivamente empregada em ambientes clínicos para a medição da velocidade e do fluxo de sangue das artérias periféricas, oferecendo uma abordagem distinta para estudar as doenças cardiovasculares. Neste trabalho, métodos computacionais foram implementados e analisados para extrair informações quantitativas de artérias a partir de imagens 2D. Os ensaios com imagens em modo-B contemplaram a combinação de técnicas de filtragem e algoritmos de contornos ativos para a detecção das interfaces das paredes arteriais e medições da EIM e do diâmetro da luz (DL). Um modelo matemático e 7 imagens reais da artéria carótida comum foram utilizados neste estudo que, dentre as diversas combinações de filtros e algoritmos, apresentou resultados quantitativos similares no cálculo do DL. Para a EIM, porém, a reduzida dimensão da camada íntima-média proporcionou variações indesejadas dos cálculos. Para medir a velocidade do sangue utilizando o modo Doppler, um método semiautomático foi incorporado a um aplicativo computacional para a detecção da envoltória do espectro do gráfico de velocidades. Uma análise comparativa entre sistemas de ultrassonografia comerciais operados por especialistas e este aplicativo incluiu a velocidade de pico sistólico e a integral de velocidade e tempo (VTI) das artérias carótida comum e braquial e de exames ecocardiográficos. A análise de Bland-Altman e o coeficiente de correlação validaram esta metodologia que, complementada pela interface gráfica amigável do aplicativo, pode auxiliar os clínicos em seus estudos de larga escala, baseados nas imagens Doppler ultrassonográficas, com as seguintes vantagens: redução do tempo operacional e de resultados subjetivos e aumento do grau de reprodutibilidade dos resultados. / In the field of image-based diagnostic medicine, low cost and noninvasive B-mode ultrasound technique have supported the researches which investigates the relation between the carotid intima-media thickness (IMT) and the development of cardiovascular diseases. Other ultrasound technique, that offers a different approach to study these diseases, is based on Doppler effect and has also been extensively used in clinical sites to measure blood velocity and flow in peripheral arteries. In this work, computational methods were implemented and analyzed to extract quantitative data from 2D images of arteries. Tests with B-mode images covered the combination of filtering techniques and active contour algorithms, in order to detect the arterial wall interfaces and to measure IMT and lumen diameter (LD). One mathematical model and seven real images of the common carotid artery were used in this study which, among several filters and algorithms combinations, showed similar quantitative results for DL measurements. However, for IMT, the small thickness of intima-media layer led to undesirable variation results. To measure blood velocity by using Doppler mode, a semi-automatic methodology was implemented in a computational tool to detect the spectrum envelope of the velocity graphic. A comparative analysis between commercial ultrasound systems operated by specialists and this tool included systolic peak velocities and velocity-time integral (VTI) of the common carotid and brachial arteries and of echocardiographic exams. Bland-Altmans analysis and the correlation coefficient validated this methodology which, besides the user friendly graphical interface of the tool, may help the clinicians for their large-scale studies based on Doppler ultrasound images, with the following advantages: to save operational time, to lower subjective results, and to support measurement reproducibility.
687

Estudo da maturação da resposta vascular da artéria mesentérica superior em recém-nascidos prematuros através do dopplerfluxometria / Evolution of superior mesenteric artery blood flow by means of doppler velocimetry in health premature neonates

Chang Yin Chia 16 April 2009 (has links)
INTRODUÇÃO: O conhecimento de valores de normalidade do fluxo sanguíneo da artéria mesentérica superior (AMS) em recém-nascidos prematuros (RNPT) saudáveis pode prevenir quadros de intolerância alimentar e a ocorrência da enterocolite necrosante. MÉTODOS: Com o objetivo de descrever a evolução dos índices de avaliação da dopplerfluxometria da AMS em RNPT saudáveis de idade gestacional entre 27 e 34 semanas completas, no primeiro, no terceiro, no sétimo e semanalmente (14, 21, 28, 35 e 42 dias de vida), foi realizado este estudo coorte prospectivo em RNPT de idade gestacional ao nascimento entre 27 e 34 semanas completas. O exame dopplerfluxométrico foi realizado, após o consentimento livre e esclarecido dos responsáveis pelos RNPT, através do aparelho Logic Book 8C-RS (General Eletric EUA); obtendo-se as seguintes medidas: pico de velocidade sistólica (PVS), pico de velocidade diastólica final (PVDF) e média de velocidade de fluxo; sendo, após, calculadas o Índice de Pourcelot, sendo: [pico de velocidade sistólico pico diastólico final] / pico de velocidade sistólico, que representa um índice de resistência (IR); e índice de pulsatilidade (IP). Foram excluídos: recém-nascidos com instabilidade hemodinâmica; em ventilação assistida com altos parâmetros; síndromes mal-formativas; intolerância alimentar ou enterocolite necrosante; fototerapia; presença de cateteres umbilicais, persistência de canal arterial e pequenos para a idade gestacional. O exame pré-prandial foi realizado antes da alimentação (até 30 minutos) e pós-prandial entre 15 e 60 minutos após a alimentação. Foram realizados no primeiro dia (entre 6 a 24 horas de vida), no terceiro, no sétimo, e após, semanalmente até 42 dias de vida. Os resultados foram expressos em médias e desvios-padrão e descritos de maneira evolutiva. RESULTADOS: Ao total, foram estudados 77 RNPT e realizados 125 exames. Os valores em média±desvio-padrão são descritos na seqüência do primeiro, terceiro, sétimo e, consecutivamente a cada semana, até 42 dias de vida; sendo: IR pré-prandial de 0,69±0,09; 0,67±0,15; 0,75±0,07; 0,74±0,07; 0,75±0,07; 0,76±0,07; 0,79±0,03; 0,78±0,05 e IR pós-prandial de 0,66±0,10; 0,70±0,21; 0,74±0,07; 0,73±0,08; 0,75±0,06; 0,76±0,06; 0,77±0,04; 0,77±0,03. Os resultados de IP pré-prandial foram: 1,45±0,30; 1,35±0,28; 1,68±0,29; 1,50±0,23; 1,47±0,22; 1,52±0,20; 1,62±0,09; 1,68±0,06 e IP pós-prandial: 1,38±0,39; 1,40±0,29; 1,58±0,26; 1,46±0,26; 1,45±0,24; 1,50±0,27; 1,58±0,10; 1,64±0,04. Obtivemos PVS pré-prandial: 60,51±22,24; 55,24±26,04; 90,61±12,74; 95,33±18,11; 92,89±15,40; 96,96±12,18; 63,18±14,08; 58,12±9,78 e pós-prandial: 59,60±24,14; 110,82±32,45; 118,10±20,15; 121,95±24,18; 124,15±25,16; 126,07±18,17; 96,68±11,12; 96,12±8,98. Quanto a PVDF pré-prandial, obtivemos: 18,85±6,09; 18,66±10,01; 20,99±8,12; 22,02±8,50; 23,04±7,89; 22,24±8,02; 11,99±6,15; 12,05±5,12 e PVDF pós-prandial: 20,63±6,89; 30,15±12,78; 27,98±9,72; 29,02±10,05; 34,56±9,00; 32,02±8,45; 19,02±4,95; 21,15±3,43. A partir dos resultados acima, demonstra-se que o fluxo sanguíneo da AMS em RNPT saudáveis apresenta uma evolução peculiar a partir do nascimento tanto dos valores basais quanto após a estimulação com a dieta, representados por uma evolução característica dos índices de resistência, melhora dos picos de velocidades sistólica e diastólica e melhora da resposta vasodilatadora após a alimentação enteral. CONCLUSÕES: RNPT saudáveis de idade gestacional ao nascimento de 27 a 34 semanas completas apresentam uma evolução do fluxo sanguíneo da artéria mesentérica superior de maneira peculiar, do nascimento até 42 dias de vida, tanto dos valores basais quanto em resposta à alimentação. O conhecimento destes valores pode indicar a dopplerfluxometria como um método preventivo de avaliação específico de cada RNPT para a introdução e progressão mais segura da alimentação, reduzindo a ocorrência de quadros gastrintestinais, melhorando os índices de morbi-mortalidade neonatal. / INTRODUCTION: The knowledge of the normal values of indices of Doppler velocimetry of the superior mesenteric artery in healthy premature neonates may help to prevent feeding intolerance situations and necrotizing enterocolitis. METHODS: In order to describe the indices for evaluation of Doppler velocimetry of the superior mesenteric artery in healthy premature neonates with gestational age between 27 and 34 weeks, on the first, third, seventh days, and then weekly, until six weeks of life; this is a prospective cohort study. The Doppler velocimetric examination was done by means of the Logic Book 8C-RS (General Electric USA), using a 8 MHz imaging transducer, with the pulsed color Doppler readings being obtained by sonographic waves at 4 MHz. The neonate was kept in a supine position, with the transducer positioned in the epigastric region, immediately below the xyphoid appendix, obtaining two-dimensional images of the celiac trunk and of the superior mesenteric artery, a few millimeters after its emergence from the aorta in the sagittal plane. The flux measurements were obtained in the longitudinal direction of the vessel and at an angle of insonation between 0 and 20 degrees. The blood flow curves were recorded after a sequence of five stable measurements, with respect to the quality of the waves, and with respect to their audible characteristics; thus obtaining the following measurements: peak systolic velocity (PSV), end diastolic velocity (EDV) and average flow velocity; with the Pourcelot Index being calculated subsequently, that is: [peak of systolic velocity end diastolic velocity / peak of systolic velocity, which represents a resitance index (RI); and pulsatility index (PI). The values obtained were expressed as averages and standard deviations. The results were stored in an Excel database, with blind analysis after the conclusion of data gathering. Uncomplicated and appropriate for gestational age premature neonates with gestational age between 27 and 34 weeks at birth were included in the study. We adopted as criteria for exclusion from the study: neonates in unstable hemodynamic conditions; needing assisted ventilation with high parameters; large deformations or clinical syndromes; feeding intolerance or diagnosis of necrotizing enterocolitis; conditions that alter the mesenteric flow, such as: phototherapy, presence of umbilical catheters, patent ductus arteriosus and sepsis. The exams were done prior to feeding (up to 30 minutes) and after feeding (between 15 and 60 minutes). If the neonate was fasting, only one of the above parameters was measured, in order to establish behavior of the basal mesenteric flow at that moment. The exams were done on the first day (between the 6th and 24th hours of life), third, seventh days, and then weekly, until six weeks of life. Data are shown as the mean ± standard deviation and described for each postnatal age group. RESULTS: A total of 77 neonates were studied and realized 125 exams. The values of the resistance and pulsatility indices (RI and PI); peaks of systolic (PSV) and final diastolic velocity (EDV) on the first, third, seventh days, and then, on sequentially for each week until six weeks of postnatal life; as mean and standard deviations, was described: RI prior to feeding were 0,69±0,09; 0,67±0,15; 0,75±0,07; 0,74±0,07; 0,75±0,07; 0,76±0,07; 0,79±0,03; 0,78±0,05 and RI after feeding were 0,66±0,10; 0,70±0,21; 0,74±0,07; 0,73±0,08; 0,75±0,06; 0,76±0,06; 0,77±0,04; 0,77±0,03. The results of PI prior to feeding: 1,45±0,30; 1,35±0,28; 1,68±0,29; 1,50±0,23; 1,47±0,22; 1,52±0,20; 1,62±0,09; 1,68±0,06 and PI after feeding: 1,38±0,39; 1,40±0,29; 1,58±0,26; 1,46±0,26; 1,45±0,24; 1,50±0,27; 1,58±0,10; 1,64±0,04. The values of PSV prior to feeding were: 60,51±22,24; 55,24±26,04; 90,61±12,74; 95,33±18,11; 92,89±15,40; 96,96±12,18; 63,18±14,08; 58,12±9,78 and after feeding: 59,60±24,14; 110,82±32,45; 118,10±20,15; 121,95±24,18; 124,15±25,16; 126,07±18,17; 96,68±11,12; 96,12±8,98. And the results of EDV prior to feeding: 18,85±6,09; 18,66±10,01; 20,99±8,12; 22,02±8,50; 23,04±7,89; 22,24±8,02; 11,99±6,15; 12,05±5,12 and EDV after feeding: 20,63±6,89; 30,15±12,78; 27,98±9,72; 29,02±10,05; 34,56±9,00; 32,02±8,45; 19,02±4,95; 21,15±3,43. These results shows that healthy premature neonates with gestational age between 27 and 34 weeks presents a peculiar evolution in blood flow in the superior mesenteric artery after birth, represented by the resistance patterns caracteristics, improvement in peaks of systolic and diastolic velocity, and improvement in vasodilation in response to feeding. CONCLUSION: These results suggest for the Doppler velocimetry as specific and preventive evaluation method for each premature neonate, as a way to a safer introduction and progression of feeding, reducing the prevalence of gastrointestinal inflammatory diseases in neonates, and improving the indices of neonatal morbidity and mortality. Knowledge of blood-flow velocity in the superior mesenteric artery in uncomplicated preterm infants might provide a clue in investigating the maturation of intestinal circulation and the pathogenesis or pathophysiology of gastrointestinal diseases in newborn infants.
688

Novel vascular markers and therapeutic strategies for the prevention of vein graft failure in a pig model of carotid artery-saphenous vein interposition grafting.

January 2009 (has links)
Kang, Ning. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstract also in Chinese. / Abstracts --- p.i / Abbreviations --- p.v / List of Figures and Tables --- p.vii / Contents --- p.viii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1. --- Saphenous vein graft patency after coronary artery bypass grafting --- p.1 / Chapter 2. --- Mechanism of vein graft failure and therapeutic strategies --- p.8 / Chapter 2.1 --- Mechanism --- p.15 / Chapter 2.2 --- Therapeutic strategies --- p.18 / Chapter 3. --- Summary --- p.22 / Chapter 4. --- References --- p.23 / Chapter Chapter 2: --- Animal model and laboratory investigations --- p.34 / Chapter 1. --- Surgical procedure --- p.35 / Chapter 2. --- Postoperative management --- p.37 / Chapter 3. --- Adenoviral-mediated gene transfer ex vivo for gene therapy study --- p.38 / Chapter 4. --- Laboratory investigations --- p.39 / Chapter 5. --- Statistical analysis --- p.40 / Chapter 6. --- Summary --- p.41 / Chapter 7. --- References --- p.41 / Chapter Chapter 3: --- "Impact of osteopontin expression in vein grafts on VSMC migration, proliferation, and neointimal formation" --- p.42 / Chapter 1. --- Introduction --- p.42 / Chapter 2. --- Methods and materials --- p.43 / Chapter 3. --- Results --- p.43 / Chapter 4. --- Discussion --- p.49 / Chapter 5. --- Summary --- p.52 / Chapter 6. --- References --- p.53 / Chapter Chapter 4: --- Potential Role of gene therapy in prevention of vein graft failure --- p.56 / Chapter 1. --- Vectors --- p.56 / Chapter 2. --- "Reporter gene, timing and titer" --- p.57 / Chapter 3. --- Candidate genes --- p.58 / Chapter 4. --- Summary --- p.64 / Chapter 5. --- References --- p.66 / Chapter Chapter 5: --- Conclusions --- p.70 / Acknowledgements --- p.72
689

Changes in the central nervous system after bilateral occlusion of the common carotid arteries in the hypertensive rats and the effect of Pien Tze Huang. / CUHK electronic theses & dissertations collection

January 2010 (has links)
Brain stroke is considered as one of the three diseases that threaten human health all over the world. Hypertension and cerebral arteriosclerosis are thought to be the most dangerous risk factors of brain stroke, and they frequently occur together, leading to ischemia of brain tissue. Unfortunately, it is not clear whether the pathological changes resulting from hypertension are related to those resulting from cerebral arteriosclerosis. There have been no ideal animal models mimicking the pathological changes in such a combined condition. In this thesis, an animal model of hypertension combined with cerebral arteriosclerosis in rats was established by occlusion of both the left and right common carotid arteries in spontaneous hypertension rats. Pien Tze Huang (PTH), a reputed traditional Chinese medicinal complex, contains Radix notoginseng, snake bile, calculus bovis, and musk and some other components that are known to protect vessels and cells from injuries. Since different tissue injuries share many common cellular mechanisms, the protection by PTH to in nerves and the circulation systems may also be benefical to cerebrovascular conditions as well. In present experiments, PTH was used to treat hypertension rats that also developed chronic brain ischemia as a result of the bilateral carotid occlusion, and its protective role for neurons and blood vessels was investiaged. / From the data above, more severe damage could be caused by hypertension combined with chronic ischemia. The model of SHR with bilaterally occluded common carotid artery can be used to study pathological changes resulted from hypertension combined with chronic ischemia. PTH was able to protect neurons in stroke. / In the initial part of the work, patients from clinics in two cities in South and North China were compared and analysed; they had been suffering from brain ischemic stroke. About two thirds of the stroke patients were found to have hypertension before the onset of stroke. Their prognosis was significantly worse than those stroke patients without hypertension. In the hypertensive rats with occluded arteries, mean of functional magnetic resonance imaging (fMRI) examination showed that brain blood flow was very weak or even transiently became undetectable at the beginning of the acute stage of brain ischemia, but was restored one hour after the occlusion surgery. In addition, pathological changes in brains of hypertensive rats with induced brain ischemia (carotid occlusion) were examined by Nissl staining, TUNEL staining, cell death ELISA and anti-oxidation enzymes. At day 15 after ischemia, a large number of pyramid cells in the hippocampus of SHR were lost and a great deal of apoptotic cells were found in the CA1 of the hippocampus, while activities of some enzyme including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were increased. At day 30 and 60, some degenerative changes appeared to have subsided and the cells appeared morphologically normal. The activities of the above enzymes were also decreased at day 60. In WKY control rats with normal blood pressure, neurons in the CA1 were found less damaged after the bilateral carotid occlusion. It was found that apoptotic and dead cells were significantly reduced in rats with hypertension combined with chronic brain ischemia if they had been pre-treated with PTH. Moreover, brain stroke damage was less severe in this pretreated rats. / Zhang, Lihong. / "March 2010." / Adviser: WH Kwong. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 116-134). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
690

Evaluation eines Software-Pakets zur semiautomatischen Segmentation von Plaqueanteilen bei symptomatischer Arteria carotis-Stenose / Semi-automated segmentation of plaque components in symptomatic carotid artery stenosis evaluation of a software package

Kruse, Jan 02 November 2010 (has links)
No description available.

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