A stent is positioned in the SB with about one-third of its length protruding into the main branch (MB) (A, arrows) and another stent is positioned in the MB. The side-branch (SB) stent is deployed (B and C) and if angiography shows no downstream dissection, the SB balloon and wire are removed. The MB stent is deployed, crushing that portion of the SB stent lying in the MB (D and E). Post-dilation is with simultaneous inflation of a SB and a MB balloon (kissing balloons) typically to about 8 to 10 atm (F). The balloon diameters for kissing post-dilation should be sized to each downstream branch vessel diameter. Final angiography is shown in G and H.

Mini-crush differs from classical crush in that the proximal end of the SB stent is positioned adjacent to the proximal end of the SB ostium (A, arrow) so that a minimal length of SB stent is crushed (B to D). Two-step kissing involves first a high pressure (>20 atm) post-dilation of the SB ostium with a noncompliant balloon 0.25 mm smaller in diameter than nominal SB diameter (F), and then the final kissing balloon post-dilation typically at 8 to 10 atm to correct any stent distortion (G). Abbreviation as in Figure 1.

Planimetery of the side-branch ostial area (A) and lumen area (B) for calculation of area stenosis for these Liberté stents (Boston Scientific, Natick, Massachusetts).

Driver stents (Medtronic, Minneapolis, Minnesota) (upper panels) after classical crush and Vision stents (Abbott Vascular, Abbott Park, Illinois) (lower panels) after mini-crush have been cut electronically along the planes indicated by the broken line in panels B and E. The electronically cut stents were opened out (panels A, C, D, and F). After classical crush, the crushed portion of the SB stent (C, arrow) has wrapped around 1 side of the MB stent forming 3 layers of struts (C, arrow). By chance, it may have wrapped around the opposite or inferior side. After mini-crush, in contrast, there is minimal multiple layering of struts (F, arrow). Abbreviations as in Figure 1.

Stent struts opposite the SB ostium have been removed electronically (A) to allow clear viewing of the SB ostium (B and D) for these Cypher Select stents (Cordis Corporation, Miami Lakes, Florida). Before kissing post-dilation, there are 2 layers of stent struts separating the MB stent lumen from the SB lumen (B). Conventional 1-step kissing balloon post-dilation (C) partially clears the struts separating MB from SB but residual struts overlie the SB ostium (D, arrow). This residual metallic stenosis is not visible on angiography (E and F), nor is it visible when the stent is viewed on the bench from its side (E). It was present with all stent designs at all angles tested after classical crush and 1-step kissing. Abbreviations as in Figure 1.

Stent struts opposite the SB ostium have been removed electronically (A) to allow clear viewing of the SB ostium for these Driver stents. The double layer of stents before post-dilation (B) are partially cleared from the SB ostium by 1-step kissing post-dilation (C) and more fully cleared by 2-step kissing post-dilation (D). See Online Videos 1, 2, and 3. Abbreviations as in Figure 1.

When stents are crushed, especially with classical crush and before kissing post-dilation, there is a "V-shaped" trough between the MB and SB stents on the opposite side to the crushed portion (left panel, B). In this figure, by chance, a wire from the MB lumen (A) has passed outside the stents through the trough (B) before entering the SB stent (C). The post-dilating balloon following this wire will have a short course outside both stents. Upon balloon inflation, the stent strut or struts on the luminal side of the wire will be pushed out of position causing a gap in stent scaffolding (open arrow, lower right panel). Vision stents were used for this deployment. See Online Video 4. Abbreviations as in Figure 1.

There is a long portion of side-branch stent that has been crushed, lying to one side of the main branch stent so that there is a long segment of triple layering of stent struts. There is no obstruction of the main branch stent but there are 2 layers of crushed side-branch stent separating the main branch from the side-branch.

Again there is a long portion of triple layering of stents because a long portion of side-branch stent has been crushed. Although there has been conventional kissing post-dilation, there remains a considerable obstruction to the side-branch ostium by stent struts.

In this example, a minimal length of side-branch stent has been crushed so that there is minimal multi-layering of struts. Two-step kissing post-dilation, where a high pressure dilatation (>20 atms) with a noncompliant balloon across the side-branch ostium preceded conventional kissing balloon inflation cleared struts from the side-branch ostium so there was ostial obstruction. Mini-crush with steeply angled side-branches can be very similar to "T" stenting when the side-branch is stented first.

When stents are crushed, especially with classical crush and before kissing post-dilation, there is a "V-shaped" trough between the MB and SB stents on the opposite side to the crushed portion. In this video, by chance, a wire from the MB lumen has passed outside the stents through the trough before entering the SB stent. The post-dilating balloon following this wire had a short course outside both stents. Upon balloon inflation, the stent strut or struts on the luminal side of the wire were pushed out of position causing the gap in stent scaffolding shown in red.