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Purpose: To present an in vivo evaluation of the effects of stent oversizing on in-stent stenosis and on actual lumen size in normal veins.Methods: Twelve self-expanding stents were implanted in the common iliac veins of 6 minipigs, which were divided in 2 groups for follow-up at 1 and 3 months, respectively. Oversizing ranged from 119.5% to 216% of the original vessel diameter. Intravascular ultrasound (IVUS) was used to measure vessel areas at the stent edges and midpoint. In-stent stenosis and decrease in actual lumen size were evaluated with IVUS immediately after implantation and during follow-up.Results: There was a very strong positive linear regression between stent oversizing and in-stent stenosis in the 1-month model (r=0.947, p=0.004), in the 3-month model (r=0.931, p=0.007), and in the sum of these 2 groups (r=0.83, p < 0.001). Regarding the change in actual lumen size, we found a strong negative linear regression with stent oversizing in the 1-month (r=-0.754, p=0.083) and the 3-month (r=-0.562, p = 0.246) groups, but these did not attain statistical significance. However, a strong correlation between stent oversizing and a decrease in lumen size in all samples proved to be statistically significant (r=0.619, p=0.032).Conclusions: Stent oversizing was strongly correlated with increased in-stent stenosis and decreased actual lumen size at follow-up in normal non-stenotic porcine veins.

Purpose: To report the use of the self-expanding Wallstent as an alternative to prophylactic inferior vena cava (IVC) filter placement before embolization of renal carcinomas with tumor thrombus.Case Reports: Two patients, a 71-year-old man and an 88-year-old woman, were diagnosed with extensive tumor infiltration of the IVC secondary to renal cell carcinomas. Prophylactic placement of an IVC filter before transcatheter embolization was unsuccessful in both cases; a reduced space for deployment would have left part of the filter inside the right atrium. Instead, a Wallstent was used to constrain the tumor thrombus against the vessel wall and, at the same time, protect the patency of the contralateral kidney. Adequate patencies were confirmed 9 months after stenting in the first patient and after 19 days in the second patient. There were no clinical manifestations of pulmonary embolism.Conclusions: Wallstent implantation is an alternative prophylactic measure before transarterial embolization of renal carcinomas if IVC filters cannot be placed.