Aim: 

We investigated the alterations of the venous wall of the main branch as well as of the related tributary system of the rat saphenous vein, after four week application of a partial stricture.

Methods: 

Plastic clips restricting the outer diameter of the saphenous vein to 500 mm were surgically applied close to its confluence with the common femoral vein on the right leg. The left leg served as control. After four weeks, a segment just caudal the stricture was subjected to an in vitro microangiographic biomechanical test. In separate sets of animals, the whole superficial tributary system of the saphenous vein was carefully microprepared and studied videomicroscopically. Plastic casts of the tributary system were made, and specimens were also studied histologically.

Results: 

An eutrophic wall remodeling with morphological lumen reduction was observed. An extensive collateral system developed, visibly originating from a rich network of vasa vasorum with inversed flow.

Conclusion: 

The combined effect of chronically elevated pressure and reduced flow on the upstream section of the main vein branch was a morphologically reduced lumen. Development of collaterals in the venous system is complicated by the presence of valves. Blood accumulating in the main branch will be drained by a newly developed rich system of venules connected parallel, originating mostly from the vasa vasorum, and diverting blood toward long collateral veins. This newly formed portal system, however, may present a much higher haemodynamic resistance than the original main branch lumen.

(OTKA TO 32019, OTKA TO 42670, ETT 128/2006).