Liver atrophy and encephalopathy after portacaval shunt in the rat.

The effect of various types of portal diversion (portacaval, mesocaval and pancreatico-splenocaval anastomoses, portacaval transposition and arterialization) on liver atrophy and post-shunt encephalopathy was studied in the rat. Among all diversions, only portacaval anastomosis produced dramatic liver atrophy and encephalopathy. Moreover, portacaval anastomosis was also the only portal diversion which induced low body weight gain. There was no correlation between blood ammonia levels and encephalopathy. Liver atrophy was always correlated to a decrease of hepatic blood flow. Diminution of liver blood flow was only slight following partial (either mesenteric or pancreatico-splenic) diversion of portal blood and nil after portacaval transposition or anastomosis. These results suggest that: (1) pancreatic (insulin-rich) blood is not essential for maintenance of liver trophicity. Hemodynamic factors seem to be predominant in the pathogenesis of post-shunt liver atrophy. (2) Post-shunt encephalopathy arises only when total diversion of the portal blood and liver atrophy are associated.