[Experimental study of arterial microanastomoses under tension in the Wistar rat. Morphologic and histologic effects].

An experimental study was performed to evaluate the effects of tension on microsurgical anastomoses. A variable length of the common carotid artery in Wistar rats was resected to give variable degrees of tension and the artery was reanastomosed microsurgically. 42 Wistar rats were divided into 7 groups of 6 rats each according to the relative length resected. Repaired arteries were then compared histologically and functionally with the artery of the contralateral side, submitted to simple section followed by microsurgical anastomosis. Significant histological changes occurred when the length of the resected segment was greater than 13.33% of the vessel's total length. These changes included subendothelial hyperplasia, medial necrosis and thrombosis. The results of this study lead us to conclude that small degrees of tension (less than 13.33% of total vessel length in this study), have no significant effects on patency of microanastomoses. Greater tension results in changes in the laminar flow through vessels that can adversely effect patency. There are also significant histological changes that may have detrimental effects in the long term.