National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Technical aspects of aortic root sparing surgery:Structural changes occurring during different thawingprotocols of cryopreserved human aortic root allografts and thereproducibility of external aortic root annuloplasty using Coroneo ring.
Novotný, Róbert ; Hlubocký, Jaroslav (advisor) ; Vojáček, Jan (referee) ; Pirk, Jan (referee)
Aortic valve-sparing procedures treating patients with aortic root aneurysm with or without aortic insufficiency and patients with ascending aortic aneurysm and aortic insufficiency are no longer experimental and unproven procedures. A successful aortic valve-sparing or repair operation aims not only to correct the failing part of the aortic root but also to restore the intro- and the inter-component relationship of the aortic root elements to optimal dimensions and relations. The avoidance of anticoagulation therapy and prosthesis-related complications makes aortic valve repair a tempting procedure. Considering the increasing rate of cusp repair reported in scientific literature, conservative aortic valve surgery seems to be developing into aortic valve repair surgery. This Dissertation Theses are devoted to the study of some specific technical aspects of aortic root sparing surgery, namely to the study of structural changes occurring in cryopreserved human aortic root allografts and the reproducibility of Coroneo ring implantation procedure. The Introduction of these Dissertation Theses deals with the general review of aortic valve- sparing operations in the light of the historical aspects of used surgical technique, dynamic anatomy and the current situation. One part of the Introduction is...
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...
Cardiac tolerance to oxygen deprivation: the effects of inhalational and intravenous anesthetics
Říha, Hynek ; Pirk, Jan (advisor) ; Bultas, Jan (referee) ; Geršl, Vladimír (referee)
Background: Surgical procedures are invariably accompanied by the use of inhalational and intravenous anesthetics. Both groups have strong influence on cardiovascular system by the interaction with myocardial oxygen supply/demand ratio and cardiomyocyte functions at the level of cell membranes, ion channels and regulatory enzymes. Aims: 1. To examine the effects of different isoflurane concentrations on the left ventricular (LV) dimensions and systolic function in the rat. 2. To examine the effects of isoflurane-induced myocardial preconditioning (APC) on the cardiac tolerance to ischemia- reperfusion (I-R) injury. 3. To compare the influence of anesthesia, based on ketamine- dexmedetomidine (KET-DEX), on the release of biochemical markers of myocardial injury and the early postoperative course with the anesthesia, based on sevoflurane-sufentanil (SEVO), in the patients undergoing coronary artery bypass grafting (CABG). Methods: 1. We carried out transthoracic echocardiographic examination in the rats immobilized by 1.5-3% concentration of isoflurane. 2. After inducing APC by isoflurane (0.5 and 1 MAC), we evaluated ventricular arrhythmias during regional ischemia (45 min), induced by the occlusion of the left anterior descending artery, and subsequent reperfusion (60 min), using the model of...
Tolerance to acute ischemia in hypertrophic myocardium
Bešík, Josef ; Pirk, Jan (advisor) ; Šamánek, Milan (referee) ; Herget, Jan (referee)
Background: The degree of ischemic injury of the heart muscle depends not only on the intensity and duration of the ischemic insult, but also on the cardiac tolerance to oxygen deprivation. Cardiac tolerance to ischemia changes significantly during ontogenetic development neonates are more resistant to ischemia then adults. Moreover, cardiac tolerance to ischemia/reperfusion injury in adults is sex-dependent males are less tolerant than females. Individually the tolerance to ischemia decreases in certain pathological conditions, particularly in heart muscle hypertrophy. Aim: 1. The aim of this study was to answer the question whether the degree of tolerance to oxygen deprivation in hearts of spontaneously hypertensive rats (SHR) is sex-dependent and to verify the hypothesis whether cardiac tolerance of the normal neonatal heart differs from that of hypertensive rats. 2. To determine whether a higher resistence of the female hypertrophied myocardium to ischemia/reperfusion injury can be seen in clinical medicine. (...) Conclusions: We can conclude, that male and female hearts differ significantly in many parameters. Detailed mechanisms of these differences are still unknown but it is clear that they are so important that they deserve serious consideration in clinical practice and in the search for proper...
Late effect of perinatal hypoxia and pleiotropic effect of statins on acute ischemia-reperfusion myocardial injury
Malý, Jiří ; Pirk, Jan (advisor) ; Kittnar, Otomar (referee) ; Pudil, Radek (referee)
Background: In last decades there were many experimental interventions protecting myocardium against ischemia but aside from early reperfusion none of them was successfully adopted in clinical practice. In our experimental work we try to apply clinical situations into an experimental condition to find out feasible solution how to influence tolerance of myocardium to ischemia. We choose two actual clinical settings: 1. congenital cyanotic heart defects and 2. hypercholesterolemia chronically treated with statins Aim: To examine: 1. the effect of of perinatal hypoxia to the tolerance of the adult myocardium to acute ischaemia/reperfusion injury with regard to sex; 2. the effect of the acute and chronic statin treatment on the tolerance of the adult rat myocardium to ischemia. (...) The effect of perinatal hypoxia on myocardial infarct size in adult males and females was not demonstrated. 2. Acute administration of statin to rats in vivo significantly decreased infarct size expressed as IS/LV, in comparison to infarct size expressed as IS/AR the protective effect of statin administration was suggested, but did not reach statistical significance. Acute administration of statin during reperfusion significantly reduced the contractile dysfunction. However, this protective effect of statins was not present after...
Effect of perinatal hypoxia on cardiac tolerance to acute ischaemia in adult male and female rats.
Netuka, Ivan ; Pirk, Jan (advisor) ; Tošovský, Jan (referee) ; Vojáček, Jan (referee)
Background: The number of adult patients with history of hypoxaemic insult in childhood has increased significantly. Cardiac interventions performed on these individuals in adulthood have become frequent. The evidence of their possibly specific response to ischaemia while undergoing these procedures is scarce and not sufficiently conclusive. Aim: The aims can be summarized as follows: 1. to develop a method of appropriate measurement and assessement of infarct size induced by regional ischaemia on isolated perfused rat heart; 2. to examine the effect of different types of perinatal hypoxia to the tolerance of the adult myocardium to acute ischaemia/reperfusion injury with regard to sex. (...) Conclusions: The results of the present study support the hypothesis that perinatal hypoxia is a primary programming stimulus in the heart that may lead to sex-dependent changes in cardiac tolerance to acute ischaemia in later adult life. This would have important implications for patients who have experienced prolonged hypoxaemia in early life.

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