MORPHOMETRIC STUDY OF THE WALL OF THE CAUDAL VENA-CAVA AFTER IMPLANTATION OF A FILTER IN 15 EWES

The long stabilizers of the VT-LGM filter rest on large areas of the v ascular wall. The morphometric study of the layers of the vascular wal l, after implantation of filter in 15 ewes, divided into 3 groups of f ollow-up (2, 4 or 8 weeks) of 5 animals, was made at 3 levels opposite the filter and 1 level outside of it. Changes are seen for all the la yers. Filter produces intimal hyperplasia. Stabilizers are quickly iso lated from the blood flow. The thickness of the intimal hyperplasia gr ows for 4 weeks. It is more important at the base of the filter than a t its head. There is also hyperplasia of the media with no change acco rding to the follow-up or the level opposite the filter. The adventiti a becomes thinner without variation of time or level of the filter. Sm ooth muscle cells of the adventitia become less frequent and smaller. Their density, in front of the stabilizers, is the smallest by 4 week follow-up and remains the same along the stabilizer. The full thicknes s of the wall is bigger opposite the stabilizers than between them. Th e filter produces changes that are limited in time and in space. The m ost important changes are seen at 4 weeks after insertion and opposite the stabilizers.