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Design of mobile stand for suspending of electrodynamic exciter for aeroelastic phenomena testing in aviation
Vojáček, Jan ; Löffelmann, František (referee) ; Navrátil, Jan (advisor)
This Bachelor thesis deals with the design of mobile stand for carrying out ground vibration tests in aviation applications. These tests mainly judge the tolerance of aircraft against flutter. The start of the thesis deals with the teoretical background of aeroelasticity together with the historical events that led to the origins of research of such phenomenons. The second part of the tesis clarifies the motivation for designing the stand through overview of simmilar equipment avaiable on the market and through introducing the equipment used at the aircraft testing laboratory at the Institute of Aerospace Engineering. Third part of the thesis states possible approaches to the overal design of the stand and then crosses over to the chapter that discusses the chosen solution of the design. At the end there are introduced the results of modal analysis. These results state the natural frequencies occuring in the range of frequencies that normally occur while testing.
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Design of mobile stand for suspending of electrodynamic exciter for aeroelastic phenomena testing in aviation
Vojáček, Jan ; Löffelmann, František (referee) ; Navrátil, Jan (advisor)
This Bachelor thesis deals with the design of mobile stand for carrying out ground vibration tests in aviation applications. These tests mainly judge the tolerance of aircraft against flutter. The start of the thesis deals with the teoretical background of aeroelasticity together with the historical events that led to the origins of research of such phenomenons. The second part of the tesis clarifies the motivation for designing the stand through overview of simmilar equipment avaiable on the market and through introducing the equipment used at the aircraft testing laboratory at the Institute of Aerospace Engineering. Third part of the thesis states possible approaches to the overal design of the stand and then crosses over to the chapter that discusses the chosen solution of the design. At the end there are introduced the results of modal analysis. These results state the natural frequencies occuring in the range of frequencies that normally occur while testing.
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The metabolic response to acute coronary syndrome focusing on tissue factor, metalloproteinases and soluble CD40 ligand
Bis, Josef ; Vojáček, Jan (advisor) ; Mates, Martin (referee) ; Vítovec, Jiří (referee)
The metabolic response to acute coronary syndrome focusing on tissue factor,, metalloproteinases and soluble CD40 ligand Introduction: The cause of acute coronary syndrome is unstable plaque and its rupture. Pathogenesis is complex and requires various mechanisms and depends both on the composition of plaque and thrombotic activity of blood. Objectives: The main goal of this work was to assess local levels of plasma tissue factor (TF), tissue factor inhibitor (TFPI), tissue metalloproteinases (MMP-2, 3 and 9) and inhibitor of metalloproteinases-2 (TIMP-2), a highly selective C-reactive protein (CRP) and soluble CD40 ligand (sCD40L) in patients with acute coronary syndrome and with stable angina pectoris in the systemic circulation, the coronary sinus and to determine the time course of blood levels in patients with acute coronary syndrome. Methods and results: Study population include patients with coronary artery disease (CAD). In 24 patients with stable CAD (SCAD) at time of diagnostic coronary angiography, we withdrew samples from the coronary sinus (CS), femoral vein (VF) and left coronary artery (LMCA). In 29 patients with acute coronary syndrome (ACS) we took samples of venous blood also 24 hours and 7 days from the start. The samples were fixed levels of TF, TFPI, MMP-2, 3 and 9, TIMP-2, CRP, and...
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Radial approach to coronary catheterizations and interventions
Bernat, Ivo ; Rokyta, Richard (advisor) ; Vojáček, Jan (referee) ; Ošťádal, Petr (referee)
Radial approach in coronary catheterizations and interventions has been only an alternative of the femoral approach. But due to some important advantages radial approach has a chance to become the first choice in majority of catheterized patients. The most important advantage is the reduction of vascular access site bleeding complications. Additonal benefits are patient satisfaction, cost reduction, shorter hospital stay and possibility of the same-day discharge catheterizations and interventions. The aim of our work was to try to answer three open questions: 1. is it possible to catheterize majority of our patients from the left radial artery when 90% of them are right-handed ? 2. what is the optimal care for the radial artery after the procedure in prevention and treatment of radial artery occlusion? 3. is it effective to implement radial approach in primary PCI as a first approach for STEMI patients? The first part relates the left radial approach. After construction of our special variable support for the left arm and forearm we succesfully used this approach in our studies in almost 90% of patients. The second part of this work contains our randomized trial comparing two different doses of unfractionated heparin in prevention of radial artery occlusion after diagnostic cardiac catheterizations....
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Diagnosing vascular prosthesis infection by means of the FDG-PET/CT
Špaček, Miroslav ; Bělohlávek, Otakar (advisor) ; Vojáček, Jan (referee) ; Gregor, Zdeněk (referee)
Introduction: Vascular prosthesis infection (VPI) is a life-threatening complication in 0.5- 5% of cases. Early and reliable diagnosis is a necessity for adequate treatment. Computed tomography (CT) is the gold standard diagnostic method used world-wide with excellent results, but in cases of advanced graft infection. Low grade infections in non-acute patients are a diagnostic challenge requiring a new method with good diagnostic accuracy. The aim of this work is to define the accuracy of 18 F-FDG PET/CT in these settings and to identify essential parameters of its evaluation. Material and Methods: Seventy-six consecutive patients with total of 96 vascular prosthetic grafts in which infection was suspected underwent PET/CT examination prospectively. PET/CT scans were analysed in terms of presence and intensity of focal and diffuse FDG uptake, presence of anastomotic pseudoaneurysm, irregular boundary of infiltration, combination of these, and uptake ratio between graft and blood background. Also, other parameters like white blood cell count, C-reactive protein, and microbiological cultures were tested. The final diagnosis (gold standard) was based on operative/histopathological finding or >6 months clinical follow up. Results: In our series the prevalence of VPI was 57.3 % (55/96 prostheses). Among various...
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Implantation of cryopreserved mitral allograft into tricuspidal position in an experiment with sheep: Technical aspects of implantation and immediate results evaluated with the aid of epicardial echocardiography
Vojáček, Jan ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Třeška, Vladislav (referee) ; Černý, Štěpán (referee)
Aortic, mitral and pulmonary valve replacement is routinely performed with reasonable clinical results. But the optimal substitute for the tricuspid valve remains controversial. Contemporary prostheses either mechanical or bioprosthetic are associated with a high risk of thrombosis and/or structural failure. Mitral allografts could have advantages over existing prostheses, especially in patients with infectious endocarditis. We describe our first experience with cryopreserved mitral allograft processing and implantation into the tricuspid position in a sheep experimental model. Material and Methods: We subjected 20 sheep (age 1 year, weight 23 - 36 kilograms) to general anesthesia and a left thoracotomy. An epicardial echocardiographic study was performed and the mitral valve was harvested. Donor animals were put to death by intravenous anesthetics injection. Allografts were immersed into cultivation medium E 199 with an antibiotic cocktail. After 24 hours storage at the temperature of 37.0oC the valves were kept at + 5 to + 7 oC over a period of 3-5 days. Then they were transferred into the cryoprotective solution (E 199 with 10% dimethylsulfoxide) and sealed into plastic bags using a double-layer technique. Finally, they were programmed cooled and stored in the liquid stage of liquid nitrogen (- 196 oC)...
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The Prevention of the organ damage after out of hospital cardiac arrest
Karásek, Jiří ; Widimský, Petr (advisor) ; Vojáček, Jan (referee) ; Moťovská, Zuzana (referee) ; Bonaventura, Jiří (referee)
The publication summarises in four original papers the authors' results in out-of-hospital cardiac arrest (OHCA). The first paper presents a prospective observational study comparing the effect of mechanical chest compression (LUCAS) and manual chest compression (non-LUCAS) on the 30-day and 180-day survival rate of the patients affected by OHCA. The study included 278 patients (144 underwent mechanical chest compression - LUCAS, and 134 manual chest compression - non-LUCAS). There were no significant differences in restoration of spontaneous circulation (ROSC): (25% in LUCAS vs 30.6% in non-LUCAS, p = 0,35). However, we observed significantly more conversions to shock rhythm in the LUCAS group (20.7% vs 10.10%, p = 0,04). The 30-day survival rate was significantly worse in the LUCAS group (5.07% vs 16.31% in non-LUCAS, p = 0,044). In the case of 180-day survival, no significant differences were detected (9.42% in LUCAS vs 5.45% in non-LUCAS, p = 0,25). The second study examined mechanical chest compression-related injuries as a possible explanation for the mechanical compression failure in survival rates. This retrospective observational study relied on 630 patients who died during CPR that involved mechanical or manual chest compressions. The data were drawn from autopsy reports of all patients....
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Prevention of ischemic and bleeding complications in patiens with known cardiovascular disease in relation to interruption and re-administration of antithrombotic therapy during non-cardiac surgery
Ondráková, Martina ; Moťovská, Zuzana (advisor) ; Vojáček, Jan (referee) ; Miklík, Roman (referee)
Background. The analysis of the current approaches to antithrombotic treatment of cardiac patients in the perioperative period of major non-cardiac surgery was performed. The incidence of ischemic and bleeding complications in relation to the interrupted antithrombotic was observed. The study investigated the discharge antithrombotic medication in patients with atrial fibrillation (AF) after major non-cardiac surgery and the impact on one-year outcomes. Methods. The subanalysis of multicentre PRAGUE 14 study was performed. A subgroup of 366 patients (mean age 75.9±10.5 years, women 42.3%, acute surgery 42.9%) undergoing major non-cardiac surgery and having any form of AF (30.6% of the total population enrolled in the PRAGUE-14 study) was followed for 1 year. Results. Antithrombotics (interrupted due to surgery) were resumed until discharge in 51.8% of patients; less frequently in men (OR 0.6 (95% CI 0.95 to 0.35); p=0.029), and in patients undergoing elective surgery (OR 0.6 (95% CI 0.91 to 0.33); p=0.021). Patients with AF had significantly higher one-year mortality (22.1%) than patients without AF (14.1%, p=0.001). The causes of death were: ischaemic events (32.6% of deaths), bleeding events (8.1%), others (N = 51; 59.3%). Non-reinstitution of aspirin until discharge was associated with higher...
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Myocardial regeneration after intracoronary injection of autologous bone marrow-derived mononuclear cells in patients with large anterior acute myocardial infarction and late reperfusion
Skalická, Hana ; Horák, Jan (advisor) ; Vojáček, Jan (referee) ; Málek, Ivan (referee)
Myocardial regeneration after intracoronary injection of autologous bone marrow-derived mononuclear cells in patients with large anterior acute myocardial infarction and late reperfusion Objective and background: Despite the use of reperfusion therapies, outcomes in patients with large ST elevation myocardial infarction (STEMI), late reperfusion and left ventricular (LV) dysfunction is poor. We investigated longterm safety and efficacy of intracoronary injections of autologous bone marrow-derived mononuclear cells (BMNCs). Methods: 27 patients with anterior STEMI (age 59 ± 12 yrs, mean baseline LV ejection fraction (LVEF) 39±5%), who underwent percutaneous coronary intervention 4-24 hours after the onset of symptoms, were randomly assigned either to intracoronary BMNCs injection (n = 17, BMNCs group, out of which 14 underwent longterm follow-up), or to standard therapy (n = 10, Control group). The LVEF, the LV end-diastolic and end-systolic volumes (LVEDV, LVESV) and diastolic function (transmitral flow, pulmonary vein flow) were assessed by echocardiography at discharge, month 4 and 24. Myocardial perfusion was assessed using SPECT at baseline and month 4. Results: At 24-month, there was no difference in rates of serious clinical events (36% vs. 50%, p=0,54). At Month 4 LVEF improved to similar extent in...
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Aortocoronary bypass surgery with or without heartlung machine in high risk patients.
Hlavička, Jan ; Vaněk, Tomáš (advisor) ; Vojáček, Jan (referee) ; Rohn, Vilém (referee)
This dissertation entitled "Aortocoronary bypass surgery with or without heart-lung machine in high risk patients" is a summary of the findings of two published works by the author: Off-pump Versus On-Pump Coronary Artery Bypass Grafting Surgery in High-Risk Patients: PRAGUE-6 Trial at 30 Days and 1 Year, published in the journal Biomedical Papers in 2015 and Aspirin is insufficient in inhibition of platelet aggregation and thromboxane formation early after coronary artery bypass surgery, published in Journal of Thrombosis and Thrombolysis in 2009. The PRAGUE-6 study, which focused exclusively on patients with very high operative risk according to the EuroSCORE scoring system, confirmed the hypothesis of a higher incidence of combined endpoints up to the 30th day among patients operated with extracorporeal circulation, particularly acute myocardial infarctions. This significant difference was not maintained after one year after the surgery, mainly due to the increase in mortality between the 30th day and the 1st year in patients operated off-pump. The dissertation further discusses similar papers published on the topic in recent years, including the two very last meta- analyzes. The second part of the thesis follows the topic of myocardial revascularization in the field of antiaggregation therapy...
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