Vascular endoscopic and macroscopic observations after crush stenting of coronary artery bifurcations in pigs

Abstract

The crush stent technique has recently been proposed to limit the development of restenosis between drug-eluting stents implanted at coronary artery bifurcations. We studied the stent expansion, apposition to the vessel, and aspect of the overlapping stents after in vivo crush stent implantation. Crush stent implantation was performed at coronary bifurcations in anesthetized swines. The treated sites were examined using intravascular ultrasound and a vascular endoscope. The stents removed from the vessel were analyzed macroscopically. After final kissing balloon inflation, an adequate apposition of the stent to the vessel wall was confirmed by vascular endoscopy and visual inspection. However, the side-branch stent was narrowed at the site of stent overlap, and the overlapping stents in the main branch created a metal mass, which could promote the development of thrombosis. The technique of crush stent implantation with additional kissing balloon inflation is feasible and promising. However, it may be limited by thrombosis and restenosis at the carina because of stent overlapping and potential incomplete apposition. Additional studies are needed to confirm the safety and long-term clinical results of this technique.

Impact of three‐dimensional characteristics of the left main coronary artery bifurcation on outcome of crush stenting

“…Additional KB inflation has been reported to promote the stent apposition to the carina in the presence of narrow angles of bifurcation [13] and to lower the risk of restenosis [12,16]. However, even after KB inflation, incomplete stent crush or unsatisfactory stent apposition to the vessel at the ostium of the side branch have been observed in animal experiments [14] and in clinical intravascular ultrasound examinations [15]. The contributions of the 3D structure of the LMCA bifurcation to complicated stent expansions, stent deformities, and to the presence of unstented segments are not well understood.…”

“…The mechanisms of incomplete stent apposition at the ostium of the side branch include (a) distortion of the side branch stent at the distal carina, particularly likely in the presence of wide-angled bifurcation [13], (b) gradual crush of the side branch stent [14], (c) insufficient expansion of the side branch stent [15], and (d) fracture of the side branch stent [8,17]. In the present study, an unstented segment was also observed in the experiment using the 3D model of LMCA bifurcation, as well as in the two-dimensional model.…”

“…In previous studies, crush stenting was performed in between 5% and 44% of distal LMCA lesions [1][2][3][4][5][6], and was the technique of choice for true bifurcation lesions involving the left anterior descending (LAD) and left circumflex (LCX) arteries. However, it has its own limitations, including difficult subsequent access to side branches [11], procedural complexity, including final kissing balloon (KB) inflation [12], incomplete stent apposition [13 14], ostial restenosis of side branches [12,15], incomplete crush in the main vessel [14,15], higher rates of stent thrombosis, compared with stenting in simple lesion [12], and higher rates of target vessel revascularization compared with stenting for other bifurcation lesions [16].…”

Three‐dimensional modeling of double‐stent techniques at the left main coronary artery bifurcation using micro‐focus X‐ray computed tomography

“…Thus, the combination of crush stenting with final KB inflation might be expected to yield even better results. However, 75% of restenotic lesions in these studies were located at the ostium of the side branch [18][19][20][21]; this has been variously attributed to incomplete apposition between stent and vessel [12][13][14], under-expansion [21], and fracture of the side branch stent [22]. It has been shown that a wide (>708) bifurcation angle promotes the distortion of the side branch stent, which as a result, is not completely apposed to the vessel, even after KB inflation [12,13].…”

“…Recent experimental studies have demonstrated that a wide-angle bifurcation [12,13], the three-dimensional (3D) vascular structure [13,14], gradual crush [14] and stent overlap or crossing in the distal LMCA [13], can prominently contribute to incomplete apposition after double stenting. However, the impacts of spatial distribution of stent expansion and distortion of the native 3D structure have not yet been completely clarified.…”