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Development of vascular substitues for low flow peripheral vascular reconstructions
Mitáš, Petr ; Špaček, Miroslav (advisor) ; Štádler, Petr (referee) ; Rohn, Vilém (referee)
The development of vascular replacement for low flow rates is a topical issue. The model for developing the development of replacement properties, which are based on the idea of assuming the characteristics of the biological model - vena saphena and programming these properties into a model of constructed replacement is one of the possible directions of development. The presented replacement, which is the result of the work of the author's team, consists of three parts - a non-absorbable scaffold representing the media, and two absorbable collagen layers - pseudointima and pseudoadventice. Target parameters of the prosthesis were determined by test results of the basic physical testing method - uniaxial tensile test and inflation-extension test, as well as other procedures in human saphenous specimens. The key issue is the technology of producing the collagen layer of the prosthesis. However, other manufacturing processes can also have a significant impact on vascular prosthesis properties, such as collagen hardening, antithrombogenic treatment of the inner surface of the vascular replacement, and the use of a sterilization method. Furthermore, the author deals with the development of a new female component of the three- layer vascular prosthesis of the Czech carp, which is characterized by lower...
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Immunosuppressive protocols after cryopreserved aortal allotransplantation in rats.
Špunda, Rudolf ; Špaček, Miroslav (advisor) ; Moláček, Jiří (referee) ; Rohn, Vilém (referee)
The aim of our study was to simulate in rats all aspects and techniques used in our new clinical program of cryopreserved alloarterial transplantation and investigate the influence of two immunosuppressive protocols with tacrolimus on acute rejection of these allografts. Cryopreserved abdominal aortic grafts were transplanted between Brown-Norway and Lewis rats. Tacrolimus (0,2 mg/kg daily) was administered from day 1 to day 30 (TAC1) or from day 7 to day 30 (TAC7), respectively. No immunosuppressed isogeneic (ISO) and allogeneic (ALO) rats combination served as control. Aortal wall destruction and infiltration by immunocompetent cells (MHC II+ cells of recipient origin) was studied on day 30 after transplantation. Flow cytometry was used for the analysis of day 30 sera for the presence of donor specific anti-MHC class I and II antibodies. The aortal allografts in both immunosuppressed groups showed regular morphology of aortal wall with no depositions of immunoglobulin G on day 30. The adventitial infiltration of non-immunosuppressed aortal allografts by MHC class II positive cells of recipient origin was significantly higher (ALO 20,7±6,7 cells, P <0,001) compared to both immunosuppressed groups (TAC1 5,9±5,5 cells, TAC7 6,1±5,1 cells). Anti-MHC antibodies class I and II level in peripheral blood...
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New aproaches to myocardial atrophy attenuation after mechanical unloading - Experimental study of heterotopic heart transplantation in rats
Pokorný, Martin ; Malý, Jiří (advisor) ; Ošťádal, Petr (referee) ; Rohn, Vilém (referee)
Cardiac atrophy, as a result of a long term mechanical unloading observed in patients treated with mechanical circulatory supports, represents a substantial obstacle in cardiac recovery. The first aim of this thesis was to evaluate the course of unloading-induced cardiac atrophy in healthy and failing heart. Mechanical unloading was studied in an experimental model of heterotopic heart transplantation in rats. Heart failure was experimentally induced by chronic volume overload achieved by creation of aorto-caval fistula. The second aim of this thesis was to discover if dietary induced increase in fatty acids concentration in heart tissue, specifically myristic, palmitic and palmitooleic, that are believed to promote physiological heart growth, could attenuate the course of cardiac atrophy. The third aim of this thesis was to examine if increased isovolumic loading obtained by intraventricular implantation of newly designed spring expander would attenuate the development of cardiac atrophy. The level of cardiac atrophy was evaluated as the weight loss of the heterotopically tranplanted heart compared to the control heart on days 7, 14, 21 and 28 after heterotopic transplantation. The cardiomyocyte width and the level of cardiac fibrosis was studied simultaneously. Mechanical unloading following heterotopic...
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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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Comparison between Flow in the Left Internal Mammary Artery Harvested via Sternotomy and via a Left Anterior Small Thoracotomy with Clinical Impact for the Patient
Voborník, Martin ; Harrer, Jan (advisor) ; Lonský, Vladimír (referee) ; Rohn, Vilém (referee)
Comparison between flow in the left internal mammary artery harvested via sternotomy and via a left anterior small thoracotomy with clinical impact for the patient Introduction: In the treatment of coronary artery disease (CAD), in addition to conservative therapy and percutaneous interventions, is irreplacebly belong coronary artery bypass grafting (CABG). The gold standard in the surgical treatment of CAD is CABG from a median sternotomy access using cardiopulmonary bypass (on-pump CABG). A less invasive and economically advantageous is CABG from a median sternotomy access without cardiopulmonary bypass (off-pump CABG) and last but not least CABG through a left anterior small thoracotomy (LAST) approach (MIDCAB - "minimally invasive direct coronary artery bypass"). Although the final technical implementation anastomoses is essentially identical in off-pump CABG and MIDCAB, the difference is very important during left internal mammary artery (LIMA) harvesting, especially through a LAST approach, which can be difficult for the surgeon. Aim of the study: The aim of these two studies is to assess the effect of surgical approach on the mean flow in LIMA, including short and long term clinical impact for the patient. Methods: Study 1 (nonrandomized, prospective): In our study we included 60 patients,...
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Long Pentraxin 3 - a Putative Biomarker with Predictive Value to Identify the Adverse Inflammatory Response in Cardiac Surgical Patients?
Holubcová, Zdeňka ; Manďák, Jiří (advisor) ; Lonský, Vladimír (referee) ; Rohn, Vilém (referee)
(LONG PENTRAXIN 3 - A PUTATIVE BIOMARKER WITH PREDICTIVE VALUE TO IDENTIFY THE ADVERSE INFLAMMATORY RESPONSE IN CARDIAC SURGICAL PATIENTS?) INTRODUCTION. Cardiac surgery is well established for development of systemic inflammatory response. There are still no biomarkers with significant predictive value to identify patients at risk. AIM. The aim of this study was to compare the dynamics of pentraxin 3 (PTX3) and other inflammatory biomarkers (CRP, TLR2 and IL-8) after cardiac surgery with particular regards to different postoperative clinical manifestation of inflammatory response. Furthermore to evaluate the association between perioperative inflammatory biomarkers (PTX3, CRP, IL-8, IL-18, IL-18BP, TLR2, MMP7, MMP8, sFas a sFasL) and atrial fibrillation (AF) in cardiosurgical patients. METHODS. Forty-two patients undergoing open heart surgery with the use of cardiopulmonary bypass were included in the study and divided in 2 groups according to the extent of clinical manifestation of inflammatory response: Group A (n = 21) - patients with different severity of systemic inflammatory response syndrome (SIRS) and Group B (n = 21) - patients with uneventful postoperative period (no SIRS). The same group of 42 patient were divided in 3 groups according to occurrence of atrial fibrillation (AF): Group A...
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The use of tissue modification mechanisms for preparing an autologous pericardial heart valve replacement
Straka, František ; Pirk, Jan (advisor) ; Straka, Zbyněk (referee) ; Rohn, Vilém (referee)
Currently used xenogeneic biological heart valves have several limitations in clinical practice. The main problem is the development of degenerative changes leading to valve failure. Re-surgery is required in approximately 65% of patients at 15 years after implantation. The challenge of heart valve tissue engineering is to create a new type of autologous biological heart valve prosthesis for clinical use with living cells capable of valve tissue remodeling. Several approaches are used with different types of scaffolds, and with a variety of cells and laboratory protocols. Most of them have not proven themselves, due to limitations such as scaffold immune system incompatibility, non-optimal mechanical properties, scaffold shrinkage, poor cell penetration, low extracellular matrix production and poor biomechanical properties and no remodeling potential after implantation in vivo. In the first part of the research, the objective is to compare the cellular matrix, the extracellular matrix structure and the mechanical properties of human pericardium as a potential scaffold for autologous heart valve tissue engineering with the structure of the normal human aortic heart valve. The second part of the research deals with the preparation of a dynamic culture system (a bioreactor) for in vivo human...
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Current possibilities of influence long-term patency of coronary artery bypass grafts
Skalský, Ivo ; Rohn, Vilém (advisor) ; Adamec, Miloš (referee) ; Němec, Petr (referee)
The main complication of aortocoronary reconstruction with vein grafts is restenosis in the course of time. The aim was to assess the effect of a periadventitial polyester system releasing sirolimus on intimal hyperplasia of autologous grafts. The controlled-release system comprises a polyester mesh coated with a sirolimus-eluting copolymer of L lactic acid and ε-caprolactone system designed to be wrapped around an autologous venous graft during its implantation. In vitro sirolimus release and its effects on smooth muscle and endothelial cells were assessed. In vitro, the copolymer-coated polyester mesh released sirolimus over a period of 6 weeks. Mesh-eluted sirolimus inhibited the growth of smooth muscle and endothelial cells in seven-day in vitro experiments. After seven days of sirolimus release from the mesh, smooth muscle and endothelial cell counts decreased by 29% and 75%, respectively, with the cells maintaining high viability. We implanted v. jugularis ext. into a. carotis communis in rabbits. The vein graft was either intact, or was wrapped with a pure polyester mesh, or with a sirolimus-releasing mesh. Three and six weeks after surgery, the veins were subjected to standard histological staining and the thicknesses of the tunica intima, the media and the intima-media complex were...
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Assessment of suitability of minimal extracorporeal circulation during cardiac surgery
Nikitinský, David ; Rohn, Vilém (advisor) ; Mašín, Jaroslav (referee)
Nikitinský, David - Assessment of suitability of minimal extracorporeal circulation during cardiac surgery First Faculty of Medicine Charles University in Prague Thesis supervisor: doc. MUDr. Vilém Rohn, CSc. The aim of the present Thesis is to evaluate the suitability of use of minimal extracorporeal circulation (MECC) by means of comparison with conventional extracorporeal circulation. In this work, I retrospectively compared two groups of patients who underwent heart surgery, one treated with MECC, and the other with conventional extracorporeal circulation - ECC. The patients were divided into two groups of 29 (MECC) and 51 (ECC) probands. Male patients prevailed in both groups (69% MECC; 80.4% ECC). The mean age was 70.5 years (MECC), 65.6 years old (ECC). In this work, I evaluated the amount of postoperative blood loss, number of units of blood derivatives used, the total duration of intubation, length of stay in postoperative intensive care unit, the execution time of surgery until discharge. I also evaluated the frequency of neurological complications, delirium, non-infectious pulmonary complications, gastrointestinal complications and other complications. The frequency of neurological complications in the MECC group (4 patients, 13.8%) was increased in comparison with the ECC group (1...
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