[Morphometric study of the wall of the caudal vena cava after the implantation of a filter in the sheep].
The long stabilizers of the VT-LGM filter rest on large areas of the vascular wall. The morphometric study of the layers of the vascular wall, after implantation of filter in 15 ewes, divided into 3 groups of follow-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 layers. Filter produces intimal hyperplasia. Stabilizers are quickly isolated from the blood flow. The thickness of the intimal hyperplasia grows for 4 weeks. It is more important at the base of the filter than at its head. There is also hyperplasia of the media with no change according to the follow-up or the level opposite the filter. The adventitia becomes thinner without variation of time or level of the filter. Smooth 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 thickness of the wall is bigger opposite the stabilizers than between them. The filter produces changes that are limited in time and in space. The most important changes are seen at 4 weeks after insertion and opposite the stabilizers.