Determinants of stent expansion in curved stenotic lesions: an in vitro experimental study

PURPOSE: This study compared the expansion parameters of four different new-generation balloon-expandable stents in a curved stenotic phantom model. MATERIALS AND METHODS: Five stents for each length and type, each with a 3.5-mm diameter (AVE, 12 mm and 18 mm; Penta, 13 mm and 18 mm; BX-Sonic, 13 mm and 18 mm; and Jostent Flex Master, 12 mm and 16 mm), were implanted in curved silicon models 3.25 mm in diameter with 58% concentric elastic stenoses. The forces exerted on the inner curvature were continuously registered. Minimal luminal diameter (MLD) and reference luminal diameter (RLD) of the stents, inflated balloon diameter at both ends of the stents during inflation (BD(ref)), and balloon diameter at the stenotic site during inflation (BD(min)) were determined by magnification radiography. RESULTS: The Penta and AVE stents presented greater RLD (Penta, 3.78 mm +/- 0.08; AVE, 3.75 mm +/- 0.13; BX-Sonic, 3.47 mm +/- 0.06; Jostent, 3.28 mm +/- 0.06) and MLD values (Penta, 2.94 mm +/- 0.18; AVE, 3.05 mm +/- 0.19; BX-Sonic, 2.68 mm +/- 0.06; Jostent, 2.53 mm +/- 0.09) than the BX-Sonic and Jostent stents. Displacement forces after stent placement were greater for AVE (0.034 N +/- 0.015) and Penta stents (0.023 N +/- 0.017) than for BX-Sonic (0.013 N +/- 0.007) and Jostent stents (0.009 N +/- 0.007; P <.05). BD(min) was correlated in a linear fashion with MLD (r = 0.84; P <.001), as was BD(ref) with RLD (r = 0.92; P <.001), for all stents. CONCLUSIONS: Inflated balloon diameter was the main determinant of stent expansion. The AVE and Penta stents gained larger MLD values than the BX-Sonic and Jostent stents, but they excessively dilated the nonstenotic region of the model.