Coronary morphologic findings after stent implantation

Clinical studies demonstrated a reduction of acute complications by high-pressure stenting. This study was performed to correlate the histomorphologic changes of the vessel wall after coronary stenting with stent expansion pressure. We studied the effects of intravital and postmortem stenting on coronary morphology in human hearts. Artifact-free analysis and morphometry of the artery segments’ cross section was performed after plastic resin embedding and cutting and grinding sectioning. By comparing intra- and postmortem findings we demonstrated that postmortem stent implantation can serve as an adequate model to study the mechanical effects of coronary stenting. A consistent histologic feature was eccentric stent expansion. Larger calcified areas of the vessel wall were not deformed by implanted stents. The highest degree of vessel injury and deformation was apparent in anatomically “nondiseased” or only slightly fibrotic parts of the arterial wall. Dissections were predominantly located directly adjacent to calcified plaques and appeared as “half-moon”-like tears reaching into the arterial media. A statistically significant stent lumen gain was found when the implantation pressure was increased up to 15 atm. Stent symmetry was not influenced by the applied implantation pressure but depended mostly on local coronary morphology. Thus, increasing implantation pressures during coronary stenting seemed to improve the stenting result up to 15 atm. When applying histomorphologic criteria, the higher pressures (>15 atm) did not cause further optimization of stent expansion. Morphometric analysis of stents implanted postmortemly and intravitally revealed comparable results. Postmortem stenting seems to be an appropriate model for studying stent expansion and stenting results in human coronary arteries.