Two-stage occulsion of the protal vein in the rat:survival related to weight variation and the interval between partial and total occulusion.

A portal vein stenosis with a diameter of 1.1 mm was performed in female Wistar rats of four different weight groups. The mortality rate was found to increase with increasing weight of the animals, a near linear correlation between mortality rate and body weight being found. Severe circulatory disturbances of the small intestine with haemorrhage and necrosis of the bowel wall were a prominent finding at death. In the survivors total occulsion was carried out at varying times, from 48 h after the first operation, and the mortality rates were recorded. A major contributing cause of death appeared to be ischaemic infarction of the liver. Only a slight congestion of the duodenum was found and no circulatory disturbance of the small intestine. Thus by 48 h the porto-systemic collaterals are sifficiently developed to prevent subsequent venous congestion. The survival rates showed a significant increase when the time interval between partial and total occlusion was extended from 48 to 72 h. This may be due to an increased blood flow through the hepatic artery and collateral arteries to the liver.