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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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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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Posttransplant function of ischemically impaired organs (pancreas, kidney, islets) preserved by perfluorocarbon (PFC)
Marada, Tomáš ; Adamec, Miloš (advisor) ; Špatenka, Jaroslav (referee) ; Kříž, Jan (referee)
(English) Perfluorocarbons (PFC) are hydrocarbons in which some or all of the hydrogen atoms are replaced with fluorine. PFC have a very high capacity for dissolving oxygen. They are chemically and biologically inert. The most successful clinical application of PFC is the "two-layer method" for pancreas preservation before islet isolation. The two-layer organ preservation method (TLM) is based on oxygenated perfluorocarbon overlaid with University of Wisconsin (UW) solution. In experiment it has been successfully used for heart and intestine transplantation. We tested whether this technique would prevent tissue damage and improve results of kidney, pancreas and islets of Langerhans transplantation with prolonged ischemia time in an experimental model of syngenic rats. In kidney and islets of Langerhanse transplantation model we used TLM preservation method. In pancreas transplantation model we used perfluorohexyloctane (PFH) as a new generation of less lipophilic PFC. 1. Kidneys were stored for 24 hours either in UW solution (n = 16), with TLM (n = 16) or transplanted immediately (control group, n = 12). In half of the animals, survival was observed and in the other animals grafts were procured for semiquantitative histological scoring and TUNEL apoptosis assessment 24 h after transplantation....
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Mechanical properties of mitral allografts
Hlubocký, Jaroslav ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Rosenberg, Josef (referee)
Mitral allograft has never been as widely used as the aortic one for the treatment of infective endocarditis in clinical practice. Results of mitral valve replacements with mitral allograft were poor. Development of better techniques of mitral valve repair and improving quality of valve prostheses led surgeons to abandon use of mitral allografts in mitral position. On the other hand that technique could be helpful for treatment of tricuspid valve pathology, mainly of infectious endocarditis. We were evaluating the possibility of inserting a cryopreserved mitral allograft into the tricuspid position in a sheep experimental model. Within the framework of this experimental project the mechanical properties of the cryopreserved mitral allograft were tested. A novel methodology of graft tissue mechanical properties testing was developed. It reflexes the surgical technique of mitral allograft transplantation as it investigates whole functional unit composed of mitral annulus, leaflet, chordae tendinaea, and papillary muscle together. A five-parameter Maxwell model was applied to characterize the viscoelastic behavior of sheep mitral valves. A control group of 39 fresh mitral specimens and a test group of 13 cryopreserved mitral allografts processed according to the tissue bank standards were tested. The testing...
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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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Fresh arterial allograft in vascular surgery - immunosuppression in experiment
Matia, Ivan ; Adamec, Miloš (advisor) ; Stingl, Josef (referee) ; Špatenka, Jaroslav (referee)
Arterial allografts are used nowadays as a modality in the treatment of vascular prosthesis infections. Prolonged administration of immunosuppressive drugs seemed to be essential for long time patency rates of alloarterial vascular reconstructions. Nevertheless, the use of immunosuppressives if there exists an acute infection is controversial. My experimental work described herein studied effects of a delayed low-dose FK 506 administration on the development of acute rejection changes 30 days after aortal transplantation in rats. The response of the recipient's immune system to aortal wall antigens of the donor in the field of no immunosuppression resulted in an intimal proliferation and its infiltration by immunocompetent cells of the recipient, necrosis of medial smooth muscle cells, including deposition of immunoglobulines, and a massive adventitial infiltration of CD4 and CD8 positive cells. On the other hand, all the principal histological signs of rejection listed above were suppressed by FK 506 administration, no matter whether the immunosuppressive was administered on Day 0 or Day 7 after the transplantation.
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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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