A bovine pericardial conduit was developed in the laboratory incorporating the principle of crimping used for synthetic vascular prostheses. The pericardium was processed in glutaraldehyde and the tube was crimped by a technique which preserves the integrity of collagen fibres. This vascular substitute presents a non-thrombogenic and non-porous inner surface which does not require preclotting and does not leak. The material is very soft, easy to handle and suture, coapts nicely to suture lines resulting in a hemostatic anastomosis. The crimping design provides longitudinal elasticity and resistance to collapsing, retains its shape with bending and avoids kinking. Crimping provides a circular tube which makes the construction of the anastomosis easier. Experimental studies in dogs demonstrated absence of thromboembolism with the conduit implanted in the abdominal aorta. Fibrin accumulation was not noted in the convexities of the crimps. This conduit was designed for aortic and pulmonary reconstruction and available in different sizes with or without a biological valve. Initial clinical experience included its use in 10 patients with aortic dissections or aortic aneurysms from August 1989 to March 1990. A reconstruction of the abdominal aorta was performed in 2 patients, the descending thoracic aorta in 2, the ascending aorta in 2 and the ascending aorta including the aortic valve and reimplantation of coronary arteries in 4. For the latter 4, composite crimped pericardial tubes containing a porcine bioprosthesis were used. An additional patient with a single ventricle underwent a Fontan type operation also employing a valved crimped pericardial conduit.(ABSTRACT TRUNCATED AT 250 WORDS)
Objective: A protective layer of endothelial cells (EC) of host origin on the entire surface of bioprosthetic heart valves has never been reported. Current commercial bioprosthetic heart valves are commonly preserved in glutaraldehyde (GA) and are cytotoxic to host cells preventing spontaneous endothelialization. The aim of this study is to demonstrate the potential for in vivo endothelialization of heart valves treated by the L.-Hydro™ preservation process.Method: L-Hydro™ preservation process consists of mild extraction of antigenic substances by the action of polyethyleneglycol and incorporation of an antiinflammatory and a anti-thrombotic agent. Seven stented porcine valves treated by the L-Hydro™ process and three GA-fixed porcine valves were implanted in the mitral position of juvenile sheep. The valves were evaluated by echocardiography and angiography prior to sacrifice at five months. Recovered valves were also histologically and histochemically evaluated.Results: There were no hemodynamic differences between the groups. However, scanning and transmission electron microscopy showed a nearly complete coverage of EC on the surfaces of all leaflets in the L-Hydro™ treated valves. The EC were in direct contact with the underlying collagen layer and expressed von Willebrand-related antigens (vW).The surfaces of the GA-treated valves were covered by fibrin deposition, macrophages, calcium and thrombotic material. Only sparse EC were observed and contact of the EC where the underlying tissue was incomplete.Conclusion: These data indicate that L-Hydro™ treated porcine valve tissues are capable of inducing spontaneous endothelialization with evidence of strong cell attachment of the new endothelium to the collagen matrix. Descriptors: Bioprosthesis. Heart valve prosthesis. glutaraldehyde. Endotelização in vivo das biopróteses cardíacas: preservação convencional versus não-aldeídica
Calcification of glutaraldehyde-treated bioprosthetic heart valves is a major cause of long-term failure. We studied porcine aortic valves treated by the L-Hydro process and implanted into 14 juvenile sheep (group 1). Another 10 sheep were implanted with glutaraldehyde-treated porcine bioprostheses (group 2). The animals were sacrificed after 150 days and the explanted valves were analyzed for calcification. Hemodynamic measurements by echocardiography and angiography were carried out prior to sacrifice. Macroscopic analysis showed calcification and loss of mobility of the leaflets in all group 2 implants and in one group 1 implant. Light microscopy showed foci of calcification in all group 2 implants and in 3 valves from group 1. A significant reduction in the level of calcification was found in porcine bioprostheses treated by the L-Hydro process and implanted into the juvenile sheep model.
This 12-year follow-up shows a very low incidence of primary allograft failure for patients older than 15 years undergoing mitral valve replacement, and much superior than our results with porcine bioprosthesis in the same age group. This supports our assumption that this investigational valve represents a new advance in cardiac valve surgery.
E -Implante de tubo valvulado bioprótese "stentless" em posição aórtica: estudo experimental em ovinos. Rev Bras Cir Cardiovasc 2002; 17(1): 90-8. INTRODUÇÃOO tratamento das lesões valvares representa um grande desafio dentro da cirurgia cardiovascular, pois, até os dias atuais, não temos um substituto ideal para as valvas do coração.Ao contrário das lesões da valva mitral, em que é possível realizar procedimentos conservad o r e s , a t u a n d o -s e e m t o d a s a s e s t r u t u r a s RESUMO: Introdução: O tratamento das lesões valvares representa um grande desafio dentro da cirurgia cardiovascular, pois, até os dias atuais, não temos um substituto ideal para as valvas do coração. As próteses atualmente disponíveis apresentam vantagens e desvantagens; as mecânicas exigem anticoagulação definitiva e as biológicas apresentam baixa durabilidade. Para se chegar a um substituto ideal, são necessárias várias fases, desde a escolha e o preparo do material até o implante em animal de grande porte. Esta última é muito importante, pois a escolha do animal deve ser criteriosa. Ovinos juvenís são animais dóceis de fácil manipulação e suas características anatômicas e biológicas se assemelham muito ao que ocorre com o ser humano e as próteses "stentless" são substitutos mais próximos dos homoenxertos.Material e Método: Foram operados 30 ovinos juvenís com idade variando de 4,4 a 6,3 meses, peso de 25 a 37 kg, sendo 28 machos. Todos os animais foram submetidos a circulação extracorpórea para implante de bioprótese "stentless" montada em tubo de aorta porcina, com reimplante de artérias coronárias. A operação foi realizada com hipotermia moderada e cardioplegia gelada. O período de seguimento foi de 30 dias e, ao final, realizado ecocardiograma.Resultados: Houve 8 (26,6%) óbitos no intra-operatório e 6 (27,7%) óbitos no seguimento. O tempo médio de CEC foi de 98 min. Foi realizado ecocardiograma em 16 animais e em nenhum caso foram vistos sinais de endocardite ou outras alterações; a fração média de ejeção foi de 74%.Conclusão: Este modelo experimental utilizando ovinos para o estudo de biopróteses "stentless" em posição aórtica mostrou-se bem reprodutível e a performance do enxerto bastante factível de ser avaliada, pois ovinos são animais dóceis e de fácil manipulação no seguimento tardio. DESCRITORES: Valva aórtica, cirurgia. Implantle de prótese vascular. Biopróteses.RBCCV anatômicas desde o anel valvar até os múscu-los papilares; a valva aórtica possui estrutura anatômica mais simples, onde os procedimentos conservadores são menos variados e com resultados pouco satisfatórios quando comparados com as plastias realizadas na valva mitral. Por esta razão, com raras exceções, o tratamento das lesões severas da valva aórtica, quase sempre, representa a troca da mesma.
Objective: A protective layer of endothelial cells (EC) of host origin on the entire surface of bioprosthetic heart valves has never been reported. Current commercial bioprosthetic heart valves are commonly preserved in glutaraldehyde (GA) and are cytotoxic to host cells preventing spontaneous endothelialization. The aim of this study is to demonstrate the potential for in vivo endothelialization of heart valves treated by the L.-Hydro™ preservation process. Method: L-Hydro™ preservation process consists of mild extraction of antigenic substances by the action of polyethyleneglycol and incorporation of an antiinflammatory and a anti-thrombotic agent. Seven stented porcine valves treated by the L-Hydro™ process and three GA-fixed porcine valves were implanted in the mitral position of juvenile sheep. The valves were evaluated by echocardiography and angiography prior to sacrifice at five months. Recovered valves were also histologically and histochemically evaluated. Results: There were no hemodynamic differences between the groups. However, scanning and transmission electron microscopy showed a nearly complete coverage of EC on the surfaces of all leaflets in the L-Hydro™ treated valves. The EC were in direct contact with the underlying collagen layer and expressed von Willebrand-related antigens (vW). The surfaces of the GA-treated valves were covered by fibrin deposition, macrophages, calcium and thrombotic material. Only sparse EC were observed and contact of the EC where the underlying tissue was incomplete. Conclusion: These data indicate that L-Hydro™ treated porcine valve tissues are capable of inducing spontaneous endothelialization with evidence of strong cell attachment of the new endothelium to the collagen matrix. Descriptors: Bioprosthesis. Heart valve prosthesis. glutaraldehyde. Endotelização in vivo das biopróteses cardíacas: preservação convencional versus não-aldeídica In vivo endothelialization of cardiac bioprostheses: conventional versus non-aldehyde preservation 145 NINA, VJS ET AL-In vivo endothelialization of cardiac bioprostheses: conventional versus non-aldehyde preservation
Experiência inicial da utilização do xenoenxerto valvado porcino na via de saída do ventrículo direito em cardiopatias congênitas
RESUMO : O crescimento de micobactérias atípicas foi observado em estudos experimentais in vtlro de fragmentos de válvulas aórticas porcinas após tanning em solução de glutaraldeído a 0,625%. Foram incubados 100 fragmentos de valvas distintas em 4 meios de cultura diferentes, em um total de 400 culturas, utilizando-se os meios de Thioglycollate , Brain-Heart-Infusion , Sabouraud-Dextrose líqüido e Micosel, que permaneceram estéreis por 72 horas. Prolongando-se o tempo de incubação e utilizando-se técnicas especiais de repique e meios especiais para as subculturas, verificou-se o crescimento ' de micobactérias atípicas a partir do 5~ dia, em 23% das amostras, a partir de culturas nos meios de Thioglycollate e Sabouraud, identificados laboratorial mente como Mycobacterium chelonei. Testes posteriores demonstraram resistência desta micobactéria à ação bactericida do glutaraldeído e sua eliminação completa ocorreu após a ação do formaldeído associado ao surfactante.
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