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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.
701

Alternativní možnosti získání autologních cévních náhrad v kardiovaskulární chirurgii / Alternative autologous vascular grafts in cardiovascular surgery

Loskot, Petr January 2016 (has links)
Introduction: Cardiovascular surgery is a relatively young but progressively evolving field in medicine. More specifically, in the past decades, cardiac surgery achieved significant advances in understanding the causes, progression and treatments of ischemic heart disease (IHD). The IHD is the most common coronary disease, and it ranks first in morbidity and mortality in the developed world. It justifies the need for significant fundamental research as well as its study in clinical practice. It now includes specialized cardiovascular centres with the complex specialized treatments. A group of interventional cardiologists capable of performing routine examinations of the coronary veins using selective angiography has been established. They can eventually also perform percutaneous coronary interventions with direct stent implants. Thus the advances have been made in comprehensive indication of the patients towards their optimal treatments under the regime of a cardio-team. Such team comprises of a cardio-surgeon, interventional cardiologist, echocardiography specialist and the attending physician who is usually the cardiologist. The IHD treatments involve preventive cardiology with the regime measures and checks, pharmacotherapy, interventional cardiology and cardiac surgery to spa treatment and...
702

An evaluation and comparison of metabolic and clinical changes in patients with acute coronary syndrome undergoing on-pump and off-pump coronary artery bypass surgery

Crous, Altia. January 2013 (has links)
Thesis ( M. Tech. (Clinical Technology )) - Central University of Technology, Free State, 2013 / The best approach to surgical myocardil revascularization remains controversial. It is already known that an inflammatory response exists due to several factors related to the use of CPB. physiological stress response which leads to an increase in pro-inflammatory markers still remains during OPCAB surgery. surgery induces a wide haematological and hemodynamic changes. Hemodynamic and metabolic optimization is of daily importance in the hospital environment. morbidity and mortality. Lactate is also often used to predict clinical outcomes and complications but controversy remains about using this measure because of discrepancies in The aim of the study was to evaluate how metabolic and clinical changes relate to the incidence of complications and clinical outcomes in ACS patients undergoing on-pump and off-pump CABG Sixty patients diagnosed with ACS who received CABG surgery were recruited to participate in the study (30 patients on-pump and 30 patients off-pump). Patients not receiving isolated with reference to the intra-operative and post-operative metabolic data, intra-operative hemodynamic data and post-operative clinical outcomes/complications. lactate levels <5mmol/L or patients with lactate levels >5mmol/L. Comparisons between the two groups were made with reference to the intra-operative and post-operative metabolic data, Intra-operative metabolic data indicated 11 (37.0%) on-pump patients and 6 (20.0%) off-pump patients had peak lactate levels of >5mmol/L during cardiac surgery. The difference between the statistically comparison, the difference cannot be considered clinically relevant. differences (p<0.05) between the lactate < 5mmol/L group and the lactate > 5 mmol/L group. Intra-operative hemodynamic data showed statistically significant differences between the on- Post-operative metabolic data showed statistically significant differences (p<0.05) between the on-pump and off-pump groups for acid-base balance variables, pH, HCO3- and BE (B) from The metabolites, glucose and lactate, showed statistically significant differences (p<0.05) between the on-pump and off-pump groups from admission to ICU until 12 hours post- Despite the fact that elevated lactate levels have been described to be associated with adverse outcomes in paediatric- as well as general intensive care admission, no specific lactate level has surgery. Lactate values for the on-pump group were significantly higher during the immediate post- resulting in vasoconstriction and a redistribution of blood flow away from the peripheral tissue and the splanchnic circulation, creating an environment for increased lactate levels in the tissue. indication of a patient's likelihood of experiencing various complications. Both groups recovered to lactate levels of <2mmol/L by the 24th hour post-operatively. According to operatively this is associated with an increased 60-day mortality. The study did show a statistically significant difference between the on-pump and off-pump comparison, the difference cannot be considered conclusive and we can only make suggestions as to the trends seen in the data. Elevated lactate levels show that they may be poorly correlated with clinical outcomes and in order to see a more definite relationship between peak lactate levels and clinical outcomes, a larger study population will be required or perhaps a different lactate cut-off value should be considered. It may also be more useful to see if there is a positive correlation between the duration of time a patient is subjected to peak lactate levels of >5mmol/L and clinical outcomes. We recommend larger study population and change lactate cut-off value to >10mmol/L.
703

Nachweis von Mikroemboliesignalen mittels transkraniellem Dopplerultraschall nach Stentimplantation der Arteria carotis interna

Zerweck, Christof 09 February 2016 (has links) (PDF)
Hintergrund: Das Auftreten von frühen postinterventionellen Komplikationen nach Stenting der Arteria carotis interna (ACI) wird auf die Embolisierung von Material aus dem Stentsegment zurückgeführt. Zerebrale Thrombembolien können nicht invasiv mittels transkraniellem Dopplerultraschall (TCD) als mikroembolische Signale (MES) detektiert werden. Studienziel : Die Studie wurde durchgeführt um Prädiktoren zu finden, welche eine hohe Anzahl von MES im Intervall einer Stunde nach dem Eingriff voraussagen könnten. Methodik: Bei 134 konsekutiven Patienten, die ein Stenting der ACI erhielten, wurde postinterventionell über eine Stunde eine TCD der ipsilateralen Arteria cerebri media durchgeführt. Zur Identifizierung von klinischen, morphologischen und prozedurabhängigen Parametern für vermehrte MES, wurde eine multivariate logische Regressionsanalyse durchgeführt. Ergebnisse: Bei 134 Patienten (111 männlich, 23 weiblich, mittleres Alter 69,7 Jahre) wurden in 38% MES detektiert (Mittelwert 4 MES/h; Streuung von 1-62MES/h). Zwei Variablen waren mit einer erhöhten postinterventionellen MES Rate vergesellschaftet. Diese waren: Symptomatische Läsionen (p=0,048) und erhöhtes Gesamtcholesterin (p=0,037). Die duale Thrombozytenaggregationshemmung (ASS und Clopidogrel) konnte als unabhängiger Prädiktor (p=0,0001) für eine erniedrigte MES Rate festgestellt werden. Schlussfolgerungen: Postinterventionelle MES konnten am häufigsten bei symptomatischen Läsionen und bei Patienten mit Hypercholesterinämie festgestellt werden. Deren Anzahl viel im Verlauf ab. Das Stentdesign hatte keinen Einfluss auf die Anzahl der gemessenen MES. Die Kombinationstherapie mit ASS und Clopidogrel war ein Prediktor für eine erniedrigte cerebrale Embolisationsrate. Die TCD der MES Rate könnte eine brauchbare Methode sein um mögliche Risikofaktoren für neurologische Komplikationen nach Stenting der ACI zu entdecken und somit die Sicherheit der Stentingprozedur der ACI zu verbessern.
704

Assessing the psychosocial risk factors for coronary artery disease: an investigation of predictive validity for the psychosocial inventory for cardiovascular illness

Baker, Maria Kathryn 27 May 2010 (has links)
This dissertation investigated the psychometric properties and clinical applications of the Psychosocial Inventory for Cardiovascular Illness (PICI). The PICI is an inventory developed to measure the psychosocial risk factors for heart disease including anxiety, depression, stress, social isolation, and anger. The inventory was developed to measure the ways that each psychosocial risk factor contributes to the coronary artery disease process through the lifestyle behaviors and pathophysiological mechanisms with which they are associated. The primary purpose of the study was to examine predictive validity for the PICI. With support for predictive validity, the inventory may aid in early identification of individuals at increased risk for coronary artery disease (CAD) so that behavioral, psychosocial, and medical interventions can be implemented. Both healthy and cardiac samples were used in the inventory development and validation process. The PICI was administered in conjunction with similar inventories and physiological markers of CAD were collected including percent of coronary artery blockage and history of heart attacks. Item analysis and factor analysis were used to yield a 20-item PICI comprised of three subscales to include Negative Affect, Social Isolation, and Anger. It was hypothesized that the PICI subscales would predict group membership; whether or not a participant carried a diagnosis of CAD, and would be have a strong relationship to the physiological markers of CAD that were measured. Analysis revealed that the PICI was unable to predict diagnostic status and did not have a strong relationship with the physiological markers of CAD. Results suggest that the PICI has acceptable reliability and construct validity as demonstrated in the current sample, yet further investigation must be conducted to gain support for the instrument’s predictive abilities. / text
705

Tracking delivery of a drug surrogate in the porcine heart using photoacoustic imaging and spectroscopy

Furdella, Kenneth J., Witte, Russell S., Vande Geest, Jonathan P. 13 February 2017 (has links)
Although the drug-eluting stent (DES) has dramatically reduced the rate of coronary restenosis, it still occurs in up to 20% of patients with a DES. Monitoring drug delivery could be one way to decrease restenosis rates. We demonstrate real-time photoacoustic imaging and spectroscopy (PAIS) using a wavelength-tunable visible laser and clinical ultrasound scanner to track cardiac drug delivery. The photoacoustic signal was initially calibrated using porcine myocardial samples soaked with a known concentration of a drug surrogate (Dil). Next, an in situ coronary artery was perfused with DiI for 20 min and imaged to monitor dye transport in the tissue. Finally, a partially DiI-coated stent was inserted into the porcine brachiocephalic trunk for imaging. The photoacoustic signal was proportional to the DiI concentration between 2.4 and 120 mu g/ml, and the dye was detected over 1.5 mm from the targeted coronary vessel. Photoacoustic imaging was also able to differentiate the DiI-coated portion of the stent from the uncoated region. These results suggest that PAIS can track drug delivery to cardiac tissue and detect drugs loaded onto a stent with sub-mm precision. Future work using PAIS may help improve DES design and reduce the probability of restenosis. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
706

The effect of a cooling cuff and moist ice pack on radial artery blood flow and lumen diameter

Gernetzky, Joshua January 2014 (has links)
Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2015. / Background: When a soft tissue injury occurs the blood vessels and surrounding tissue are damaged leading to haemorrhaging and inflammation. Cryotherapy (cold therapy) is generally acknowledged as the preferable treatment by manual therapists during this immediate post-traumatic period of an injury. Cryotherapy has been shown to result in vasoconstriction decreasing the rate of blood flow which has a favourable effect on inflammation and pain. The commercially available cooling cuff is a relatively new cryotherapy modality offering a mechanism of cooling that does not require freezing and is easy to use. The polymer granules within the cooling cuff are activated by emersion in water therefore freezing is not required making the cooling cuff readily available compared to more traditional forms of cryotherapy. Aim: The aim of this study was to determine the effect of a moist ice pack and a commercially available cooling cuff radial artery blood flow (cm.s-1) and radial artery lumen diameter (mm) after 15 minutes of application. Method: This study was a pre-test post-test design utilising 43 asymptomatic participants that were randomly allocated to one of two groups. Each group either received a standard moist ice pack or a commercially available cooling cuff, placed on the ventral surface of the participants forearm, over the radial artery, for a duration of 15 minutes. Measurements were taken with a Doppler ultrasound to determine radial artery blood flow and lumen diameter, prior to the intervention and 15 minutes after the cryotherapy application. Data analysis was performed using IBM SPSS VERSION 20 (IBM Corp. Released 2010.IBM SPSS Statistics for Windows, Version 19.0. Armonk, New York: IBM Corp.). Statistical significance was set at a p< 0.05 level. Intra-group and inter-group comparisons were measured using repeated measures ANOVA testing. Results: Both the moist ice pack and commercially available cooling cuff resulted in a significant decrease in radial artery blood flow (p< 0.001) after 15 minutes of application with no significant changes being observed in radial artery diameter Conclusions: The commercially available cooling cuff resulted in a similar effect on radial artery blood flow and lumen diameter as moist ice, indicating that the commercially available cooling cuff may be utilised in the acute phase of an injury to alter blood flow. / M
707

Embolização de malformações arteriovenosas periféricas com uso de cateter-balão de duplo lúmen / Peripheral arteriovenous malformations embolization with dual-lumen balloon catheter

Stamoulis, Dimitrius Nikolaos Jaconi 11 June 2018 (has links)
Introdução: As malformações arteriovenosas são lesões congênitas caracterizadas por uma rede capilar malformada (nidus) que comunica o sistema arterial e venoso em um mecanismo de shunt arteriovenoso não irrigando tecido normal. Devido ao shunt arteriovenoso as MAVs apresentam alto fluxo sanguíneo, podem ser assintomáticas ou sintomáticas dependendo de sua localização. O tratamento das MAV busca a exclusão circulatória completa do nidus o que pode ser alcançado por meio de ressecção cirúrgica, radiocirurgia ou embolização endovascular. Objetivo: descrição técnica de uma série de dois casos de MAVs de localização periférica (fora do sistema nervoso central), que foram tratadas através da embolização com uso de cateter-balão de duplo lúmen. Materiais e métodos: Trata-se de estudo retrospectivo que avaliou os pacientes submetidos a embolização com cateter-balão de duplo lúmen para o tratamento das MAVs periféricas pelo Setor de Radiologia Intervencionista do HCFMRP-USP. Resultados: Os achados encontrados foram consistentes com a literatura atual demonstrando altas taxas de sucesso técnico e clínico, sem complicações inerentes ao procedimento. Conclusão: O uso destes dispositivos se mostrou mais eficaz em obliterar completamente o nidus deste tipo de lesão, além de reduzir o tempo de procedimento, a exposição à fluoroscopia. Neste estudo foi obtida a exclusão angiográfica completa das MAV em uma única sessão de embolização e não foram descritas complicações relacionadas ao tratamento. / Introduction: Arteriovenous malformations are congenital lesions characterized by a malformed capillary network (nidus) that communicates the arterial and venous system in an arteriovenous shunt mechanism and does not irrigate normal tissue. Due to the arteriovenous shunt AVMs present high blood flow, they may be asymptomatic or symptomatic depending on their location. The AVM treatment seeks the complete circulatory exclusion of the nidus which can be achieved by means of surgical resection, radiosurgery or endovascular embolization. Objectives: A technical description of a series of two cases of peripheral AVMs that were treated through embolization using a dual-lumen balloon catheter. Materials and methods: This is a retrospective study that evaluated patients undergoing embolization with a double-lumen balloon catheter for the treatment of peripheral AVMs by the Interventional Radiology Sector of HCFMRP-USP. Results: The findings were consistent with the current literature demonstrating high rates of technical and clinical success, without complications inherent to the procedure. Conclusion: The use of these devices has been shown to be more effective in completely obliterating the nidus of this type of lesion, in addition to reducing the procedure time, exposure to fluoroscopy. In this study complete angiographic exclusion of AVM was obtained in a single embolization session and no complications related to treatment were described.
708

Design and Validation of an Arterial Pulse Wave Analysis Device

Salter, Geoffrey Douglas 17 November 2006 (has links)
Student Number :9900127Y - MSc (Eng) dissertation - Faculty of Engineering and the Built Environment / Arterial pulse wave analysis studies the wave shape of the blood pressure pulse. The pulse wave provides more information than the extreme systolic and dia- stolic pressures, measured with a cuff sphygmomanometer. The aim of the research is to investigate the design issues in a pulse wave analysis system, and to compare these to a commercially available system. The system was compared and validated by measuring the pulse wave at the radial artery (wrist) using the non-invasive technique of arterial tonometry. The design conformed to the IEC-601 safety standard to ensure patient safety. The data was compared against the data from the commercial system and analysis was performed in the time and frequency domain. The performance of the design suggests that, in some respects, the design was comparable to the commer- cial system, however, a number of performance characteristics fell short of the commercial system. Suggestions have been made to address these problems in further research.
709

Contribution à la modélisation mécanique du comportement dynamique, hyperélastique et anisotrope de la paroi artérielle / Contribution to the mechanical modelling of the dynamic, hyperelastic and anisotropic

Masson, Ingrid 10 December 2008 (has links)
>Les maladies cardiovasculaires sont la première cause de mortalité dans le monde et font actuellement l’objet de nombreuses recherches. Dans le cas d’études des artères, un des objectifs est d’améliorer la compréhension des mécanismes biologiques impliqués dans des maladies comme l’hypertension, l’athérosclérose ou l’anévrisme. Les études mécaniques qui ont été menées s’appuient essentiellement sur des approches expérimentales in vitro, ce qui en limite leur intérêt et application dans le diagnostic clinique. Dans ce travail, un modèle théorique de comportement mécanique 3D de l’artère carotide prenant en compte le caractère hyperélastique, anisotrope, actif, précontraint et dynamique de la structure est proposé. Les mesures expérimentales sont obtenues in vivo sur des carotides communes de rats d’une part, et humaines de manière non invasive, d’autre part. Le problème mécanique aux limites est résolu semi-analytiquement sur un cycle cardiaque, considérant le tissu environnant. Les valeurs optimales des paramètres du modèle, en particulier de ceux décrivant les caractéristiques mécaniques de microconstituants pariétaux (élastine, collagène, muscle lisse), sont évaluées par régression non linéaire. Le modèle proposé permet (i) de reproduire les évolutions de pression luminale mesurées in vivo et (ii) de donner une évaluation des distributions de contraintes pariétales cohérentes avec la physiologie artérielle. Une corrélation entre l’âge des patients et les paramètres décrivant les contraintes résiduelles et les fibres de collagène, montre l’intérêt du modèle théorique et l’originalité de cette approche qui pourra donc être utilisée dans l’étude de pathologies artérielles. / Cardiovascular diseases are the number one cause of death globally and they are currently the subject of many researches. In studies of arteries, one of the aims is to improve understanding in biological mechanisms involved in diseases such as hypertension, atherosclerosis or aneurysm. The mechanical studies that were carried out predominantly rely on in vitro experimental testing, which limit their interest and application in clinical diagnosis. In this work, a theoretical modelling of the 3D carotid artery mechanical behaviour is proposed by assuming a hyperelastic, anisotropic, active, pre-stretched and dynamic wall structure. The experimental measurements were obtained in vivo from rat and human common carotid arteries, with non invasive recordings in the human case. The mechanical boundary value problem is solved semi-analytically over a cardiac cycle by also assuming the surrounding perivascular tissue. The best-fit values of the model parameters are estimated by nonlinear least-squares method, in particular those describing the mechanical characteristics of wall microconstituents (elastin, collagen, smooth muscle). The proposed modelling is able (i) to reconstruct the in vivo dynamic measured intraluminal pressures and (ii) to compute the wall stress fields which seem to be consistent with the arterial physiology. A correlation between patient age and the parameters related to residual stresses and collagen fibres shows the relevance of the theoretical modelling and the originality of the approach which, thereby, would be able to be used in studies of arterial pathological cases.
710

Avaliação ultrassonográfica da involução dos componentes do cordão umbilical de bezerros holandeses no primeiro mês de vida: influência da concentração da tintura de iodo utilizada para a desinfecção do umbigo / Sonographic evaluation in involution of the umbilical cord components in Holstein calves in the first month of life: influence of the iodine concentration used for the disinfection of the navel

Bombardelli, Juliana Aparecida 14 August 2015 (has links)
As afecções dos componentes umbilicais merecem destaque no período neonatal, pois são comumente encontradas nos bezerros, podendo levar a graves complicações. O diagnóstico das doenças umbilicais muitas vezes não é totalmente esclarecido pela palpação abdominal bimanual, uma vez que, em parcela dos casos, esse método semiológico não é sensível para determinar o grau de acometimento das estruturas umbilicais intra-abdominais. Assim, a ultrassonografia apresenta-se como um valioso exame complementar para o estabelecimento de um diagnóstico preciso sobre a localização e extensão das onfalopatias intra-abdominais. Diante dessas limitações e da raridade de pesquisas com estabelecimento de padrões da ultrassonografia do umbigo, a proposta desse estudo foi avaliar o processo de involução fisiológica dos componentes umbilicais de bezerros sadios, considerando o uso de antisséptico clássico, a tintura de iodo, em concentrações de 2% e 5%, usado na cura do umbigo nos primeiros dias após o nascimento. A avaliação foi realizada por meio do exame ultrassonográfico dos componentes umbilicais, em diferentes posições, caracterizando as modificações ocorridas durante o processo de involução, em relação ao aspecto das imagens, com medidas de diâmetro e espessura dos componentes vasculares e úraco, assim como às peculiaridades decorrentes dos dois tipos de desinfecção da região. Foram avaliados 23 bezerros da raça Holandesa, machos, oriundos de propriedade leiteira localizada no Estado de São Paulo, desde o nascimento até os 30 dias de vida. Os resultados obtidos, evidenciaram que a veia e as artérias umbilicais perdem as suas características de vasos, assumindo aspecto de ligamento devido à proliferação de tecido fibroso. Esse processo caracterizou-se e seguiu um padrão, no qual o tecido fibroso inicialmente estava presente na região interna da parede do vaso, seguindo, com a involução, em direção ao centro da luz vascular. Esse processo de involução é mais precoce em porções dos vasos mais distantes do umbigo externo, não havendo distinção de comportamento determinada por uso das diferentes concentrações do antisséptico. Além das imagens, foram também padronizadas as medidas do diâmetro dos componentes umbilicais e da espessura de suas paredes, ao longo do processo de involução fisiológica, durante os primeiros 30 dias de vida dos bezerros, comprovando-se a precisão do exame ultrassonográfico para essa avaliação e estabelecendo-se referências ultrassonográficas para fundamentar o diagnóstico e escolha do tratamento das onfalopatias / Diseases of the umbilical components are very important in the neonatal period. Commonly found in calves, they can lead to serious complications. Diagnosis of umbilical diseases is often not fully enlightened by bimanual abdominal palpation, since this semiotic method is not sensitive enough to determine the extent of involvement of the umbilical intra-abdominal structures in part of the cases. Thus, ultrasonography is a valuable complementary test for establishing an accurate diagnosis on the location and extent of intra-abdominal omphalitis. Because of these limitations and the scarce research on the establishment of the standards of navel ultrasound, the purpose of this study was to evaluate the physiological involution process of umbilical components of healthy calves, considering the use of classic antiseptic, iodine tincture in concentrations 2% and 5%, used in navel treatment during the first days after birth. Evaluation was performed by ultrasonography of umbilical components in different positions and the changes were characterized during the process of involution regarding the appearance of the images, the measures of the diameter and thickness of vascular and urachus components, as well as the peculiarities from the two types of disinfecting. Twenty-three Holstein male calves, reared in dairy property located in the State of São Paulo, were evaluated from birth to 30 days old. Results obtained showed that the vein and umbilical arteries lose their blood vessels characteristics, assuming a ligament aspect due to fibrous tissue proliferation. This process was characteristic and followed a pattern, in which the fibrous tissue was initially present in the inner part of the vessel wall, following with involution, toward the center of the vessel lumen. This process of involution was earlier in the parts of the blood vessels that were farthest from the external navel, with no particular behavior distinct by the use of different antiseptic concentrations. Besides the images, the measurements of the diameter of the umbilical components and the thickness of their walls were also standardized along the physiological involution process during the first 30 days of life the calf, confirming the accuracy of ultrasonography for such assessment and establishing references to improve the diagnosis and the choice of treatment of umbilical diseases

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