Influence of Iliac Vein Stent Implantation on the Contralateral Iliac Vein

Objectives: Stent implantation is frequently used to treat iliac vein occlusion. However, the recommended extension of the stent mesh into the inferior vena cava (IVC) may affect blood flow through the contralateral iliac vein. We analyzed the influence of iliac vein stent extension on contralateral iliac vein patency and neointima formation in a dog surgery model. Methods: Bare stents were implanted into the left iliac veins of 12 beagles with the proximal end covering the opening of the contralateral iliac vein. Blood flow was measured by color Doppler 4, 8, and 12 weeks postoperation. At each measurement point, a subgroup was killed, and the stents and veins were removed for pathological examination. Results: Stents were successfully implanted, and there was no immediate stent occlusion or iliac vein thrombus by color Doppler examinations. Contralateral blood flow was maintained with no obvious abnormalities for 12 weeks. Neointima formed and advanced toward the center of the stent, but small coverage of the contralateral iliac vein opening did not change significantly with time postoperation (9.33% 1.54% at 4 weeks, 10.65% +/- 1.01% at 8 weeks, and 10.92% +/- 1.30% at 12 weeks; P > .05). Scanning electron microscopy showed neointima covering the surface of stent wires at the opening of the contralateral iliac vein, which did increase with time: 63.58% +/- 12.39% at 4 weeks, 97.13% +/- 2.71% at 8 weeks (P < .001 vs 4 weeks), and 99.63% +/- 0.60% after 12 weeks (P > .05 vs 8 weeks; P < .001 vs 4 weeks). The neointimal coverage rate of the meshes increased obviously with time. However, no neointima was found forming a mesh between stent wires. Conclusion: Although there was intimal hyperplasia on the rim of the bare stent in the IVC, expansion was limited and did not block the opening of the contralateral iliac vein. The stent had no obvious influence on blood backflow in the contralateral iliac vein.