Expansion of WallStents® after Initial Deployment in Nonthrombotic Iliac Vein Lesions.

Background: To determine the structural changes of Wallstents (Boston Scientific, Natick, MA) in vivo following deployment in iliac veins.

Methods: This retrospective single-center study was performed from September 2012 to April 2013 and included 100 office-based patients who underwent initial stent placement for nonthrombotic iliac vein lesions with Wallstent as well as a second procedure for stenting of the contralateral iliac vein. Measurements were obtained with marker balloons and the diameters of the stents were compared at the time of the index procedure to the secondary procedure.

Results: The average time between the 2 procedures was 28 days (range 3-237, SD ± 39.89). The overall average stent diameter after the index procedure was 16.38 mm (range 10.95-21.45, SD ± 2.24). The overall average stent diameter of the index stent when remeasured during the second intervention was 17.58 mm (range 12.84-24.11, SD ± 2.38, P = 0.0003), which was significantly different from the initial measurements. There was no difference when comparing changes in stent diameter by gender or laterality of procedure. However, there was a significant difference in expansion of stents when placed in the common iliac vein versus the external iliac or common femoral veins.

Conclusions: This study shows that self-expanding Wallstents can continue to expand days to weeks in vivo following initial deployment. Additionally, we found that the change in diameter from initial placement to follow-up was more significant in stents placed in the proximal and middle segments of the common iliac vein.

Clinical relevance: Wallstents are durable implants designed to last within a patient for the rest of their life, it is important to understand the structural changes occurring after their placement. This study allows for a better understanding of Wallstent dynamics in vivo.