Difference in security of stent jail between Palmaz-Schatz, NIR, and multi-link stents: The effect of balloon inflation through stent struts

After placing a stent in the main vessel of a bifurcation lesion, it is oft en necessary to perform further balloon inflation or stent placement throug h the stent struts in order to treat a lesion of the secondary vessel or si de branch. This balloon inflation with dilatation through the cells of the stent in the main vessel results in stent strut disfigurement. This disfigu rement causes various degrees of stenosis within the main vessel secondary to stent strut deformity. The degree of strut deformity, and therefore sten osis, may vary significantly depending on stent design and structure. A mod el of a bifurcation lesion with an angle of 45 degrees was created from acr ylic resin. The diameters of the main vessel and the secondary vessel were both 3.5 mm. Deployment of the Palmaz-Schatz stent (PS, n = 5), NIR stent ( n = 5), or Multi-Link stent (n = 5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 6 atm. A second 3.5-mm balloon cathete r was then inflated to 6 atm through the stent struts of the main vessel an d into the ostium of the secondary vessel. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch and the st enosis within the main vessel were then measured, taking into account the s tent deformity that occurred. Kissing balloon dilatation with two 3.5-mm ba lloon catheters was then performed and the stenosis secondary to stent defo rmity in the main vessel was remeasured. The MLD of the Multi-Link stent at the side-branch ostium was greater compared with those of the Palmaz-Schat z stent or the NIR stent (2.4 +/- 0.1, 1.6 +/- 0.1, 1.7 +/- 0.1 mm, P < 0.0 1) and CSA (4.9 +/- 0.5, 2.7 +/- 0.3, 2.5 +/- 0.3 mm(2), P < 0.01). Balloon inflation through the stent struts caused stent deformity that resulted in some degree of stenosis within the stent of the main vessel in all three s tent types. Kissing balloon inflation reduced, but never eliminated, this s tenosis, The percent stenosis in the main vessel secondary to stent deformi ty (PS 34% +/- 9%, NIR 25% +/- 8%, Multi-Link 34% +/- 7%, NS) and residual stenosis postkissing balloon inflation (PS 12% +/- 1%, NIR 10% +/- 3%, Mult i-Link 14% +/- 3%, NS) were not significantly different among these three s tents. At the side-branch ostium, the MLD and CSA were significantly greate r for the Multi-Link stent compared with those of the Palmaz-Schatz or NIR stent. Balloon inflation through the stent struts caused stent deformity th at resulted in stenosis within the stent in the main vessel. Kissing balloo n inflation reduced this stenosis, but some residual stenosis always remain ed. The stenoses within the main vessel did not differ among the three sten t types. (C) 1999 Wiley-Liss, Inc.