Significance of venous drainage for small-bowel allografts

Small bowel transplantation has proved feasible in rats and in larger animal, but several important questions have yet to be answered before it becomes a potential therapy in man. One consideration is the site of venous outflow of the allograft. Portal drainage, however, re-establishes the physiological route of venous outflow, while systemic drainage creates a partial mesocaval shunt, the metabolic consequences of which have not been studied in detail. Using the canine model in partial mesocaval shunt and porta-caval shunt, we compared the metabolic and histological changes following each shunt. The metabolic changes in Eck were hyperammonemia and amino acid imbalance, while those in partial mesocaval shunt were similar to controls. The histological appearance of the liver in Eck was atrophy, fatty infiltration and deglycogenation, while that in partial mesocaval shunt was completely normal except for minimal fatty degeneration. These data suggest that there is no metabolic or histological disadvantage of systemic venous drainage as compared with control, and because of its technical simplicity, systemic venous drainage may be preferable in small bowel transplantation.