Orthotopic partial hepatic transplantation in dogs

Um novo modelo para estudos sobre lesão de isquemia e reperfusão hepáticas em cães

A lesão de isquemia e reperfusão hepáticas que ocorre no transplante de fígado não está completamente elucidada. Vários modelos experimentais com objetivo de estudos fisiopatológico e de modulação farmacológica desta condição têm sido propostos. Um desses modelos, proposto para cães, compreende a isquemia de 30% da massa hepática com descompressão portal translobar através dos restantes 70% de parênquima hepático. No presente trabalho, 10 cães foram submetidos à desvascularização de uma maior massa hepática (70%), seguida de reperfusão, com descompressão venosa esplâncnica através dos lobos caudado e lateral direito (30%) (Grupo Teste), durante o período de isquemia. Dez outros cães foram submetidos à operação simulada (Grupo Controle). Os resultados indicaram com um grau de confiança de 95% que: 1. Durante o período de isquemia verificou-se estabilização da PAM e da PVC, elevação da pressão portal (PP) semelhante à desenvolvida com o uso de "bypass", diminuição significativa da temperatura corporal(TC) sem atingir níveis médios aquém de 36oC, ausência de acidose metabólica ou aumento dos níveis de enzimas (AST, ALT e DL), presença de necrose hepática (NH) e queda do conteúdo de glicogênio hepático (CGH); 2. Após a reperfusão do fígado constatou-se queda da PAM, ausência de diferenças significativas de PVC , permanência de níveis elevados de PP, decréscimo da TC, presença de acidose metabólica (¯ pH, ¯ DB), aumento significativo e progressivo de aminotransferases (AST, ALT), desidrogenase láctica (DL) e necrose hepática (NH), bem como declínio progressivo do conteúdo de glicogênio hepático (CGH). Os resultados sugerem que o modelo proposto pode ser útil para estudos de fisiopatologia e de modulação farmacológica da lesão de isquemia e reperfusão do fígado, utilizando uma maior massa hepática.

Orthotopic transplantation of a partial hepatic autograft in dogs

The purpose of this study was to investigate the availability of an orthotopic transplantation of partial hepatic autograft in dogs as a means of surgical training. Male mongrel dogs weighting 10-15 kg were used. The left lobe of the liver was harvested while preserving the left branches of the portal vein, hepatic artery and bile duct, and the left hepatic vein. The remnant liver was removed while preserving the inferior vena cava using a veno-venous bypass. Orthotopic transplantation of the autograft was performed while anastomosing the left hepatic vein to the inferior vena cava, portal and arterial reconstruction, and external biliary drainage. Thirteen out of 29 dogs survived more than 48 h after transplantation. However, 6 out of 13 dogs were sacrificed after developing bile peritonitis due to a dislodgement of the biliary catheter, and only two dogs were able to survive for 7 days after transplantation. The arterial ketone body ratio recovered to 1.0 within 1 h after reperfusion, and the ratio of the dogs that survived for more than 48 h remained above 1.0 until sacrifice. Orthotopic transplantation of a partial hepatic autograft is a useful and simple procedure to train surgeons for partial liver transplantation.

New technique of experimental partial liver transplantation: hemodynamic study during surgery

Orthotopic liver transplantation of children is often limited by the scarcity of an appropriately size-matched donor organ. The transplantation of a reduced liver was thus conceived to solve this problem. A new technique of partial liver transplantation in mongrel dogs is reported, which partially retains the recipient's liver and uses an Ameroid constrictor to occlude the recipient's portal branch gradually. The donor's right and median lobectomy was performed in situ. The donor's left lobe was perfused in situ and removed as a graft. It was then transplanted orthotopically in the space after a left and median lobectomy of the recipient. An Ameroid constrictor was applied around the recipient's right portal branch for a gradual occlusion of the host hepatic blood supply (the Ameroid group). To compare the hemodynamic stability during surgery with this technique, two other methods were also performed. The mean systemic blood pressure of orthotopic liver transplantation with a passive venovenous bypass during the anhepatic period (the Bypass group, n = 5) was lower than that of the Ameroid group (n = 16). Instead of fitting an Ameroid constrictor, an orthotopic partial liver transplantation with ligation of the right portal branch (the Ligation group) was performed. The mean systemic blood pressure of the Ligation group (n = 10) was lower than that of the Ameroid group (n = 11) after either fitting a constrictor or performing a ligation.(ABSTRACT TRUNCATED AT 250 WORDS)

Orthotopic nonauxiliary homotransplantation of part of the liver in dogs

An experimental study was carried out investigating the feasibility of using only a portion of a donor liver in orthotopic, nonauxiliary transplantation, establishing a canine model. After being totally hepatectomized, 20 immunosuppressed adult beagles received a 60% donor liver graft, derived from tissue-typed identical littermates. Preservation time was 5 hr. In control experiments, 10 beagles, only half of them immunosuppressed, underwent an operation involving complete liver mobilization, vascular exclusion, cooling of the liver in situ, and a 40% partial hepatectomy with biliary anastomosis. The surgical procedure, including the method of cooling and preservation, is described in detail. Survival rate amounted to 90% for the control group and 50% for the transplanted group, while all surviving dogs were sacrificed 24 wk postoperatively. At sacrifice, the liver weight amounted to the weight of the total native liver at operation. Body weight profiles reflect good general condition of the surviving dogs. No major differences were noted between the immunosuppressed and the nonimmunosuppressed control dogs. No complications were related to the fact that only a partial liver was grafted or left in situ.