Etude Morphométrique de la Paroi de la Veine Cave Caudale après Implantation d'un Filtre chez le Mouton

Abstract

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.

Effects of Thrombosed Vena Cava Filters on Blood Flow: Flow Visualization and Numerical Modeling

“…The evidence of recirculation zones and associated low " s w upstream and downstream of the captured clot do not appear to be conducive to clot dissolution, and may promote continued aggregation of blood elements, clot growth, and intimal hyperplasia. Furthermore, our computational evidence along with recent in vivo evidence 1,24,27 suggests that the total length of filter wires pressing against the vessel wall should be minimized.…”

“…16 Studies have suggested the formation of intimal hyperplasia near the wall struts of the Vena Tech filter. 1,24,27 This one-stage filter has parallel wires in contact with the caval wall much like the TrapEase. Low " s w near the wires may be associated with the formation of hyperplasia observed, but more studies are needed to confirm this.…”

“…In animal studies of the Vena Tech filter, intimal hyperplasia of the vena cava was observed near the wall struts. 1 Fibrous evolution of trapped thrombus led to the formation of fibrous webs between the wall struts and IVC wall in a follow-up study. 5 In a comparison study of stents implanted in the canine aorta and IVC, medial hyperplasia of the IVC associated with thrombus formation led to incorporation of the stent wires into the vessel wall.…”

“…The parallel wires in contact with the IVC wall may also lead to hyperplasia or incorporation into the vessel wall, as has been observed in the Vena Tech filters. 1,27 The effects in vivo of the resulting blood flow asymmetry and WSS on thrombus lysis, aggregation, and intimal hyperplasia is unknown.…”