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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.
41

Medida do strain bidimensional do ventrículo esquerdo pré-implante percutâneo de endoprótese valvar aórtica: correlação com a evolução após o procedimento / Measurement of bidimensional strain of left ventricle before percutaneous implantation of aortic valve endoprosthesis: correlation with evolution after the procedure

Lucas Arraes de França 24 May 2017 (has links)
INTRODUÇÃO: O implante transcateter de prótese valvar aórtica (TAVI) surge nos dias atuais como uma opção terapêutica para os pacientes sintomáticos portadores de estenose aórtica grave. Cerca de 200 mil pacientes em todo o mundo já foram submetidos ao TAVI. Não há grandes estudos que tenham avaliado a correlação prognóstica entre parâmetros ecocardiográficos antes do TAVI e eventos cardiovasculares a longo prazo. É relevante analisar se o strain pré-procedimento e outros parâmetros se comportam como fatores preditores independentes de eventos após o procedimento. MÉTODOS: Foram avaliados, de novembro de 2009 a outubro de 2016, 86 pacientes, submetidos a avaliação ecocardiográfica antes do TAVI e 30 dias após o procedimento, com análise do strain do ventrículo esquerdo pelo speckle tracking bidimensional e outros parâmetros ecocardiográficos. Esses pacientes foram acompanhados clinicamente e avaliados quanto aos desfechos: mortalidade global, mortalidade cardiovascular, classe funcional de insuficiência cardíaca e necessidade de reinternação cardiovascular. RESULTADOS: O strain global longitudinal pré-TAVI reduzido (valor absoluto) aumentou a chance de reinternação cardiovascular (OR: 0,87; 0,77 ±0,99; P= 0,038). A redução da relação E/e´ em 30 dias após o TAVI associou-se à queda da mortalidade global (OR: 0,97; 0,95 ±0,99; P = 0,006), bem como valores elevados pré procedimento dessa relação se associaram a maiores taxas de insuficiência cardíaca classe funcional III ou IV da New York Heart Association após a intervenção (OR: 1,08; 1±1,18; P = 0,049). CONCLUSÃO: Os resultados deste trabalho indicam que o strain global longitudinal pré-procedimento demonstrou ser um preditor de reinternação cardiovascular pós-intervenção a longo prazo. A relação E/e´ pré-procedimento apresentou correlação diretamente proporcional com o desenvolvimento de insuficiência cardíaca classe funcional III ou IV a longo prazo, assim como sua queda acentuada 30 dias após o procedimento correlacionou-se com menor mortalidade global. / INTRODUCTION: Transcatheter aortic valve replacement (TAVR) is a therapeutic option for symptomatic patients with severe aortic stenosis. Approximately 200,000 patients around the world have already undergone TAVR. No large studies have evaluated prognostic correlation between echocardiographic parameters before TAVR and long-term cardiovascular events. It is relevant to analyze strain before procedure and how other parameters work as independent predictors of events after the procedure. METHODS: A total of 86 patients were evaluated from November 2009 to October 2016. They underwent echocardiographic evaluation before TAVR and 30 days after the procedure with analysis of strain of the left ventricle by bidimensional speckle tracking and other echocardiographic parameters. Patients were followed clinically and evaluated in relation to outcomes: global mortality, cardiovascular mortality, functional class of heart failure and need for cardiovascular readmissions. RESULTS: Global longitudinal strain before reduced TAVR (absolute value) increased the chance of cardiovascular readmission (odds ratio: 0.87; 0.77 ± 0.99; p = 0.038). Reduction of E/e´ relationship 30 days after TAVI was associated with a drop in global mortality (odds ratio: 0.97; 0.95 ± 0.99; p = 0.006). In addition, high values for this relation before the procedure were associated with higher rates of New York Heart Association functional class III or IV heart failure after the intervention (odds ratio: 1.08; 1.00 ± 1.18; p = 0.049). CONCLUSIONS: Results of this study indicate that global longitudinal strain before the procedure is a predictor of cardiovascular readmission after TAVR. The E/e´relationship before the procedure presented a correlation directly proportional to the development of long-term functional class III or IV heart failure as well as its accentuated drop 30 days after the procedure was correlated with lower global mortality.
42

Comparação da função diastólica entre o pré e pós-operatório de pacientes portadores de estenose aórtica ou insuficiência aórtica, baseados em dados bioquímicos e ecocardiográficos / Comparing after and before aortic valve replacement diastolic function in patients with aortic stenosis(AS) or aortic regurgitation(AR)

Berta Paula Napchan Boer 09 February 2010 (has links)
INTRODUÇÃO: Avaliação da função diastólica de pacientes portadores de estenose ou insuficiência aórtica submetidos à troca valvar. OBJETIVOS: Avaliação da função diastólica através da análise do NTpró-BNP como método não invasivo para caracterização da insuficiência cardíaca diastólica, comparando com os dados ecocardiográficos através do Doppler Pulsado em Fluxo Mitral, Doppler Pulsado em Veias Pulmonares e Doppler Tecidual em portadores de IAO e EAO. MÉTODOS: Foram avaliados 63 pacientes, 32 pacientes com IAO (25 pacientes do sexo masculino e 7 do sexo feminino), 31 pacientes com EAO (11 pacientes do sexo masculino e 20 pacientes do sexo feminino). As variáveis foram comparadas na média entre os pacientes portador de IAO e EAO no pré e pós-operatório. RESULTADOS: A idade dos pacientes variou de 21 a 81 com média de 55 anos. Observa-se diferença quanto à média de idades entre as diferentes patologias (t-Student p< 0,0001). Os pacientes com IAO apresentam uma média de idade igual a 45,7±14,3 com variação entre 21 e 79 anos e os pacientes com EAO apresentam uma média de idade igual a 61,5±14,7 com variação entre 21 e 81 anos. Na IAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): TRIV (p=0,0011), diferença entre Tempo de onda A mitral e onda A pulmonar (p=0,0097), Vol. Sistólico de AE (p=0,0019), Vol Sistólico de AE Indexado (0,0011), Vol. Diastólico de AE (p=0,0110), DDVE (p<0,0001), DSVE (p<0,0001), VSF (p<0,0001), VDF (p<0,0001), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa do VE (p<0,0001). Na EAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): E/E (p=0,0379), TRIV (p=0,0072), diferença entre o tempo de onda A mitral e tempo de onda A pulmonar (p=0,0176), Vol sistólico de AE(p=0,0242), Vol. Sistólico de AE indexado (p=0,0237), FEdeAE (p=0,0339), DDVE (p=0,0002), DSVE (p=0,0085), VDF (p=0,0194), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa de VE(p<0,0001). O NTpró-BNP se correlacionou positivamente com os diversos graus de disfunção diastólica tanto no pré como pós-operatório CONCLUSÃO: Foram verificados no estudo da função diastólica variação com significância estatística tanto na IAO como na EAO na comparação do pré e o pós-operatório. Da mesma forma notamos variação do NT-proBNP com correlação com as variáveis ecocardiográficas que caracterizam a disfunção diastólica. / INTRODUCTION: Assessment of diastolic function in patients with aortic stenosis or aortic regurgitation waiting for aortic valve replacement. OBJECTIVE: Assesment of diastolic function with Doppler methods:Doppler signals from transvalvar mitral inflow, tissue Doppler imaging (TDI) and Doppler in pulmonary veins(DPV) correlating with serum brain peptide natriuretic (NTproNP) before and 6 months after aortic valve replacement (AVR). METHODS: We have analyzed 63 patients, 32 with AR (25 males and 7 females), 31 AS (11 males and 20 females).The indices were compared with AS and AR before and after AVR. RESULTS: The ages of patients ranged from 21 to 81 mean age was 55 years old.We have seen difference between mean age of AS and AR (t-Student-p<0.0001). Patients with AR have had mean age 45.67 plus/minus 14.28, range 21 to 79 years old and patients with AS have had mean age 61.50 plus/minus 14.72, range 21 to 81 years old. The patients who had AR the indices showed differences: Isovolumetric Relaxation Time IRT(p=0.0011), Diference between the pulmonary A wave duration and mitral A duration (p=0.0097), Left Atrial Systolic Volume (p=0.0019), Left Atrial Systolic Volume Index(p=0.0011), Left Atrial Diastolic Volume (p=0.0110), Left Ventricular Diastolic Diameter (p<0.0001), Left Ventricular Systolic Diameter (p<0.0001), End Systolic Volume (p<0.0001), End Diastolic Volume (p<0.0001), Left Ventricular Mass Index (p<0.0001) and Left Ventricular Volume and Left Ventricular Mass Index ratio (p<0.0001). Analyzing patients with AS the indices who showed differences: (The ratio of mitral velocity to early diastolic velocity of the mitral annulus) E/E (p=0.0379)(Isovolumetric Relaxation Time)(p=0.0072) IRT, Diference between the pulmonary A wave duration and mitral A duration (p=0.0176), Left Atrial Sistolic Volume (p=0.0242), Left Atrial Systolic Volume Index (p=0.0237), Left Atrial Ejection Fraction (p=0.0339) Left Ventricular Diastolic Diameter (p=0.0002), Left Ventricular Systolic Diameter (p=0.0085), End Diastolic Volume (LVEDV) (p=0.0194), Left ventricular Mass Index(p<0.0001), Left Ventricular Volume and Mass Index Ratio (p<0.0001). CONCLUSIONS: As we studied diastolic function we have verified significant statistic variation in aortic regurgitation and aortic stenosis comparing before and after aortic valve replacement. Likewise we have seen there is correlation between NTproBNP and echocardiographic variables that show diastolic dysfunction.
43

The Development of Computational Methods and Device Design Considerations Towards Improving Transcatheter Heart Valve Engineering

Heitkemper, Megan January 2020 (has links)
No description available.
44

Fluid Flow Characterization and In Silico Validation in a Rapid Prototyped Aortic Arch Model

Knauer, Alexandra Mariel 01 August 2016 (has links) (PDF)
Transcatheter aortic heart valve replacement (TAVR) is a procedure to replace a failing aortic valve and is becoming the new standard of care for patients that are not candidates for open-heart surgery [2]. However, this minimally invasive technique has shown to cause ischemic brain lesions, or “silent infarcts”, in 90% of TAVR patients, which can increase the patient’s risk for stroke by two to four times in future years [3]. Claret Medical Inc., a medical device company, has developed a cerebral protection system that filters and captures embolic debris released during endovascular procedures, such as TAVR. This thesis utilized CT scans from Claret Medical to create a physical construct of the aortic arch to experimentally validate a theoretical computer model through flow visualization. The hypothesis was that the empirical model can accurately mimic the fluid dynamic properties of the aortic arch in order validate an in silico model using the finite elements program COMSOL MultiPhysics® Modeling Software. The physical model was created from a patient CT scan of the aortic arch using additive manufacturing (3D printing) and polymer casting, resulting in the shape of the aortic arch within a transparent, silicone material. Fluid was pumped through the model to visualize and quantify the velocity of the fluid within the aortic arch. COMSOL MultiPhysics® was used to model the aortic arch and obtain velocity measurements, which were statistically compared to the velocity measurements from the physical model. There was no significant difference between the values of the physical model and the computer model, confirming the hypothesis. Overall, this study successfully used CT scans to create an anatomically accurate physical model that was validated by a computer model using a novel technique of flow visualization. As TAVR and similar procedures continue to develop, the need for experimental evaluation and visualization of devices will continue to grow, making this project relevant to many companies in the medical device industry.
45

Evaluation of systemic inflammation in response to remote ischemic preconditioning in patients undergoing transcatheter aortic valve replacement (TAVR)

Zhang, Kun, Troeger, Willi, Kuhn, Matthias, Wiedemann, Stephan, Ibrahim, Karim, Pfluecke, Christian, Sveric, Krunoslav M., Winzer, Robert, Fedders, Dieter, Ruf, Tobias F., Strasser, Ruth H., Linke, Axel, Quick, Silvio, Heidrich, Felix M. 19 January 2024 (has links)
Background: Systemic inflammation can occur after transcatheter aortic valve replacement (TAVR) and correlates with adverse outcome. The impact of remote ischemic preconditioning (RIPC) on TAVR associated systemic inflammation is unknown and was focus of this study. Methods: We performed a prospective controlled trial at a single center and included 66 patients treated with remote ischemic preconditioning (RIPC) prior to TAVR, who were matched to a control group by propensity score. RIPC was applied to the upper extremity using a conventional tourniquet. Definition of systemic inflammation was based on leucocyte count, C-reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6), assessed in the first 5 days following the TAVR procedure. Mortality was determined within 6 months after TAVR. RIPC group and matched control group showed comparable baseline characteristics. Results: Systemic inflammation occurred in 66% of all patients after TAVR. Overall, survival after 6 months was significantly reduced in patients with systemic inflammation. RIPC, in comparison to control, did not significantly alter the plasma levels of leucocyte count, CRP, PCT or IL-6 within the first 5 days after TAVR. Furthermore, inflammation associated survival after 6 months was not improved by RIPC. Of all peri-interventional variables assessed, only the amount of the applied contrast agent was connected to the occurrence of systemic inflammation. Conclusions: Systemic inflammation frequently occurs after TAVR and leads to increased mortality after 6 months. RIPC neither reduces the incidence of systemic inflammation nor improves inflammation associated patient survival within 6 months.
46

Halteapparatkonservierende Mitralchirurgie

Drews, Thorsten 17 October 2001 (has links)
Heutzutage stellt der Erhalt des posterioren Halteapparates beim Mitralklappenersatz (MKE) ein Routineverfahren dar. Das Ziel dieser Studie war es festzustellen, ob der komplette Erhalt der subvalvulären Strukturen beim Mitralklappenersatz Vor- oder Nachteile hat. Es wird über die Erfahrungen mit 48 Patienten berichtet. Die Gruppe MKEh bestand aus 15 Patienten, bei denen beim MKE der komplette subvalvuläre Halteapparat erhalten wurde. Die Gruppe MKEo, bei denen beim MKE nur der posteriore Halteapparat erhalten wurde, bestand aus 9 Patienten. Die dritte Gruppe (MKR) enthielt 12 Patienten, bei denen die Mitralklappe rekonstruiert worden war und die vierte Gruppe (KG) bestand aus 12 Herzgesunden ohne Klappendefekt, die die Kontrollgruppe darstellte. Die Patienten wurden einer ausführlichen Befragung unterzogen sowie prä- und postoperativ echokardiographisch untersucht und die Ergebnisse verglichen. Bezüglich der Ergebnisse der Befragungen und der präoperativen echokardiographischen Ergebnisse fanden sich bei den drei operierten Gruppen (MKEh, MKEo, MKR) keine signifikanten Unterschiede. Demgegenüber wurden postoperative Unterschiede festgestellt: Bei den Patienten mit MKE, bei denen aber der vordere Halteapparat nicht konserviert wurde (MKEo), fand sich eine signifikant geringere systolische Verkürzung zwischen dem Apex und der Mitralklappenbasis (6,5 mm - 15 mm), die systolische Kontraktion begann bei diesen Patienten außerdem nicht im Bereich des Apex und der posteriore Papillarmuskel führte in diesen Fällen keine aktive Kontraktion aus. Es konnte somit die Schlußfolgerung gezogen werden, daß der komplette subvalvuläre Apparat notwendig ist, damit der linke Ventrikel eine physiologische Kontraktion durchführen kann. Er sollte somit immer beim Mitralklappenersatz komplett erhalten werden, sofern die Papillarmuskeln und die Chorden intakt sind und keine Mitralklappenrekonstruktion durchgeführt werden kann. / Today preservation of the chordal attachment to the posterior leaflet in mitral valve replacement (MVR) is a routine, universally accepted procedure. The aim of this study was to show the advantages and disadvantages of the preservation of the entire subvalvular structures. Our institution's experience with 48 patients in four groups is reported. The MKEh group consists of 15 patients who underwent MVR with preservation of the entire subvalvular structures. The MKEo group, treated with MVR and preservation of the posterior subvalvular structures only, consists of 9 patients. The third group (MVR) consists of 12 patients with mitral valve reconstruction and group 4 (CG) of 12 healthy individuals without heart valve dysfunction, as a control group. The patients were assessed by questioning and echocardiography pre- and postoperatively and the results compared. In questioning and in the preoperative echocardiography results no differences were seen between the three surgical groups (MKEh, MKEo, MKR). However, considerable differences were present in the postoperative echocardiography results: in patients without preservation of the anterior subvalvular structures (MKEo group) the shortening between the apex and the mitral valve basis is significantly less (6.5 mm - 15 mm), the systolic contraction does not begin at the apex and the posterior papillary muscle does not actively contract. It is concluded that preservation of the entire subvalvular structures is important to ensure physiological contraction of the left ventricle. They should be preserved in all mitral valve replacement operations when the papillary muscles und chordae are intact and mitral valve reconstruction cannot be performed.
47

Biomechanical Interaction Between Fluid Flow and Biomaterials: Applications in Cardiovascular and Ocular Biomechanics

Yousefi Koupaei, Atieh January 2020 (has links)
No description available.
48

Vliv miniinvazivního přístupu na respirační funkce u pacientů po aortální náhradě / Impact of Minimally Invasive Approach on Pulmonary Function in Patients Undergoing Aortic Valve Replacement

Gofus, Ján January 2021 (has links)
of the dissertation Impact of minimally invasive approach on pulmonary function in patients undergoing aortic valve replacement MUDr. Ján Gofus The most common minimally invasive approach to aortic valve replacement is upper hemisternotomy, which has been implemented at our department, as well. Preserving the lower half of thoracic cage could lead to lower postoperative drop of pulmonary function, apart from other benefits. Nevertheless, publications on this topic are insufficient and controversial. Our aim was to perform a prospective randomized trial comparing upper hemisternotomy with standard (median) sternotomy in terms of pulmonary function changes perioperatively. We also added a novel exercise tolerance test, one-minute sit-to-stand test, and a quality of life evaluation to the study. We included patients indicated for elective isolated aortic valve replacement with bioprosthesis who were older than 65 years, signed informed consent, and in which both surgical approaches were technically feasible. Exclusion criteria were re-do surgery and concomitant cardiac surgery. Patients were randomized to minimally invasive and standard group in 1:1 ratio. On the day of admission, on the 7th postoperative day and 3 months postoperatively, the patients underwent pulmonary function testing and one-minute...
49

Interventions innovantes dans le traitement des maladies valvulaires mitrales et aortiques : options de traitement actuelles et perspectives futures

El Yamani, Nidal 08 1900 (has links)
Les maladies valvulaires constituent une cause importante de morbidité et de mortalité. Dans les pays industrialisés, l’insuffisance mitrale et la sténose aortique sont les pathologies valvulaires les plus fréquentes et leur prévalence augmentent avec l’âge. Étant donné l’augmentation de l’espérance de vie dans ces pays, la prévalence des valvulopathies dégénératives deviendra plus importante et aura un impact non négligeable sur la santé publique. Les avancées en chirurgie cardiaque ainsi que les nouvelles percées en cardiologie interventionnelle ont modifié considérablement la prise en charge des patients avec des valvulopathies en offrant des approches minimalement invasives, surtout pour les patients à haut risque chirurgical. Dans le cadre de ce mémoire, deux études rétrospectives de cohorte ont été réalisées. La première consiste à comparer les résultats postopératoires et sur trois ans de la chirurgie conventionnelle par rapport à la procédure transcathéter MitraClip chez 259 patients avec une insuffisance mitrale ischémique sévère. La deuxième étude compare les résultats postopératoires de trois approches de remplacement de la valve aortique, soit la sternotomie, la ministernotomie et la minithoracotomie. La première étude permet de conclure que la procédure MitraClip a un taux de mortalité postopératoire et sur 3 ans inférieur à celui de la chirurgie mais qu’elle est associée à un plus haut taux de récurrence de l’insuffisance mitrale après 3 ans. La deuxième étude démontre que les deux approches minimalement invasives, la ministernotomie et la mini-thoracotomie, ont un taux équivalent de mortalité intra-hospitalier à la sternotomie. La mini-thoracotomie est associée à moins de saignement périopératoire et moins de douleur au repos que la sternotomie. En conclusion, les approches minimalement invasives offrent une excellente alternative à la chirurgie conventionnelle dans le traitement de la maladie valvulaire. Les bénéfices cliniques sont d’autant plus évidents lorsque les patients sont adéquatement sélectionnés; d’où l’importance d’une ‘Heart Team’ qui collabore pour une meilleure prise en charge des patients. / Valvular heart disease is an important cause of morbidity and mortality. In western countries, mitral regurgitation and aortic stenosis are the most frequent valvular pathologies and their prevalence increases with age. With the increase in life expectancy in these countries, the prevalence of degenerative valve disease will increase with a significant burden on healthcare systems. Advances in cardiac surgery as well as new breakthroughs in interventional cardiology have considerably modified the management of patients with valvular disease, by offering minimally invasive approaches, especially for patients at high surgical risk. In this thesis, two retrospective cohort studies were carried out. The first compares the postoperative and 3 years outcomes of mitral valve surgery vs MitraClip, a transcatheter procedure, in 259 patients with severe ischemic mitral regurgitation. The second study compares the postoperative results of two minimally invasive techniques (ministernotomy and minithoracotomy) for aortic valve replacement to conventional sternotomy. In the first study, MitraClip procedure had lower postoperative and 3-year mortality rate than surgery, but it was associated with higher recurrence rate of mitral regurgitation after 3 years. The second study showed that the two minimally invasive approaches had similar intrahospital mortality rate to sternotomy. Minithoracotomy was associated with less perioperative bleeding and less pain at rest than sternotomy. In conclusion, minimally invasive approaches offer an excellent alternative to conventional surgery in the treatment of valvular disease. The clinical benefits are more highlighted when patients are properly selected; hence the importance of a "Heart Team" that collaborates for better patient care.
50

Leaflet Material Selection for Aortic Valve Repair

Abessi, Ovais 21 November 2013 (has links)
Leaflet replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. Hemodynamic performance and mechanical stress levels were investigated after porcine AVr with 5 types of clinically relevant replacement materials to ascertain which material(s) would be best suited for repair. Porcine aortic roots with intact aortic valves were placed in a left-heart simulator mounted with a high-speed camera for baseline valve assessment. Then, the non-coronary leaflet was excised and replaced with autologous porcine pericardium (APP), glutaraldehyde-fixed bovine pericardial patch (BPP; Synovis™), extracellular matrix scaffold (CorMatrix™), or collagen-impregnated Dacron (HEMASHIELD™). Hemodynamic parameters were measured over a range of cardiac outputs (2.5–6.5L/min) post-repair. Material properties of the above materials along with St. Jude Medical™ Pericardial Patch with EnCapTM Technology (SJM) were determined using pressurization experiments. Finite element models of the aortic valve and root complex were then constructed to verify the hemodynamic characteristics and determine leaflet stress levels. This study demonstrates that APP and SJM have the closest profiles to normal aortic valves; therefore, use of either replacement material may be best suited. Increased stresses found in BPP, HEMASHIELD™, and CorMatrix™ groups may be associated with late repair failure.

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