Impact of longitudinal stent elongation during percutaneous coronary intervention

Background: Longitudinal stent deformation is one of the hottest topics. We experienced a case of stent elongation during stent deployment. Considering this, the following tests were performed. Methods: Four kinds of drug eluting stents (DES: Xience Prime (XP), Plomus Element (PE), Nobori (N) and Cypher select plus (CY)) with three 3x28mm stents of each were used for each test. In test 1, all stents were dilated five times at rated burst pressure (RBP) in air pressure. In test 2 and 3, all stents (except CY in test 3) were implanted in a tapered phantom model with the proximal and distal diameter being 3.5mm and 3mm respectively, at nominal pressure and single post-dilation to proximal portion of the stents was performed with RBP using 3.5x15mm semi-compliant balloon (SC) (Test 2) and 3.5x15mm high-pressure balloon (HP) (Test 3). Stent length before and after each tests were measured. To disclose the relationship between stent elongation and the types of balloon catheters (BC) used, four SC (A to D) and three HP (E to G) were also tested. Three 3mm BC with two types of the length were tested (short: 15mm in SC and 8-10mm in HP, long: 20mm in SC and 15mm in HP). All BC were inflated at nominal pressure and RBP in air pressure and the change of length (%) were checked. Results: Lengths of stent elongation was significantly different between all DESs in Test 1. However, no significant difference was observed in test 2 and 3 except for CY (Table 1). All BC elongated with RBP inflation in significantly different rates, however, similar results between short BC and long BC were observed (Table 2). View this table: Table 1. Elongation of DESs View this table: Table 2. Elongation of BC Conclusion: Longitudinal stent elongation was observed in all kinds of DESs tested, especially in new generation stents. We must considerer this phenomenon when deploying stents, especially long ones.