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Cryopreserved semilunar heart allografts: Leaflet surfase damage in scanning electron microscopy
Burkert, Jan ; Špatenka, Jaroslav (advisor) ; Černý, Štěpán (referee) ; Černý, Jan (referee) ; Třeška, Vladislav (referee)
7. Anglický souhrn: Cryopreserved semilunar heart valve allografts: leaflet surface damage in scanning elect.-on microscopy. Objective: Allograft heart va1ves (AHV), biologica1 va1ves ofhuman origin, offer potential advantages over conventiona1 xenografts in terms of superior hemodynamics and, perhaps, better durability. The most important factors for long-term AHV c1inical peďormance are the processing and cryopreservation methods. The aim ofthis study was to eva1uate the impact of current processing protocol on va1ve tissue morphology, maínly to address the effect of successive processing steps on the leaflet suďace structure. For the detection offine changes in endothelia1 covering and underlying layers, our own modification ofthe scanning electron microscopy (SEM) technique was utilized. Material and methods: The study was based on an investigation of20 AHV (40 specimens). Fourteen valves came from heart-beating donors (multiorgan harvesting) when the heart could not be transplanted for any reason (donor criteria, availability of recipient and/or logistics). Six were obtained at the time of routine postmortems - non heart-beating donors (NHBD). AU specimens were initially flxed in Bakeťs solution. Tissue samples were dissected, dried with hexamethyldisilazane (HMDS), gold-coated, studied and...
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Human heart valve allografts mechanical and morphological properties according to duration of tissue cryopreservation
Fiala, Radovan ; Burkert, Jan (advisor) ; Dominik, Jan (referee) ; Rosenberg, Josef (referee)
Background: The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not reasonably deteriorate after this period. Methods: A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction, arterial ring) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. Results: In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of...
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Cryopreserved semilunar heart allografts: Leaflet surfase damage in scanning electron microscopy
Burkert, Jan ; Špatenka, Jaroslav (advisor) ; Černý, Štěpán (referee) ; Černý, Jan (referee) ; Třeška, Vladislav (referee)
7. Anglický souhrn: Cryopreserved semilunar heart valve allografts: leaflet surface damage in scanning elect.-on microscopy. Objective: Allograft heart va1ves (AHV), biologica1 va1ves ofhuman origin, offer potential advantages over conventiona1 xenografts in terms of superior hemodynamics and, perhaps, better durability. The most important factors for long-term AHV c1inical peďormance are the processing and cryopreservation methods. The aim ofthis study was to eva1uate the impact of current processing protocol on va1ve tissue morphology, maínly to address the effect of successive processing steps on the leaflet suďace structure. For the detection offine changes in endothelia1 covering and underlying layers, our own modification ofthe scanning electron microscopy (SEM) technique was utilized. Material and methods: The study was based on an investigation of20 AHV (40 specimens). Fourteen valves came from heart-beating donors (multiorgan harvesting) when the heart could not be transplanted for any reason (donor criteria, availability of recipient and/or logistics). Six were obtained at the time of routine postmortems - non heart-beating donors (NHBD). AU specimens were initially flxed in Bakeťs solution. Tissue samples were dissected, dried with hexamethyldisilazane (HMDS), gold-coated, studied and...
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