Development of collaterals in intermittent and permanent ischemia of the liver.

The ischemia caused by the hepatic dearterialization as therapy for hepatic malignancies is transient because of the rapid formation of collaterals. In order to prevent this transient repeated ischemia has been suggested. An experimental study was planned to compare the collateral occurrence in persistent ischemia and transient repeated ischemia of the liver. Fourteen dogs (seven persistent ischemia, seven transient repeated ischemia) were used in this study. Hepatic dearterialization were performed in both groups. In the first group (persistent ischemia), the hepatic artery was ligated proximal to the gastroduodenal artery. In the second group (transient repeated ischemia), the hepatic artery was occluded externally in the same region as the first group by means of a device modified from 8 guage Foley catheter and after occlusion for one hour it was reopened. Occlusions were repeated twice in a day. Five dogs in the first group and six dogs in the second group completed a three week ischemia period and angiography were then performed in all. The dogs were sacrificed after the angiography and examined for possible abscess formation, arterial thrombosis, peritoneal adhesions and liver necrosis. After angiography, the two groups were also examined for collateral occurrence. Only one collateral occurred in the transient repeated ischemia group, but in the persistent ischemia group, collaterals occurred in all dogs. This difference between two groups is statistically significant (Fischer Absolute Chi Square Test, p = 0.013). Transient repeated ischemia is superior to persistent ischemia because of fewer collaterals, but in practise, total dearterialization of the liver is impossible.

The effects of different suture techniques on collagen metabolism in experimental distal colonic anastomoses.

Two types of suture techniques have been compared in anastomoses of the distal colon in 20 mongrel dogs. They were divided into four groups, each consisting of five dogs. In A and C groups a single layer suture technique, and in B and D groups a two layer suture technique was used. In order to determine tissue hydroxyproline activities at the suture lines, the anastomosed segments were resected on the fifth day in A and B, and on the tenth day in C and D groups. It was observed that the hydroxyproline activities in single layer anastomoses were higher than those of two layer anastomoses with the implication that there was more rapid wound healing.