Clinic of Vascular and Endovascular Surgery, RWTH Aachen University Hospital, Aachen, Germany.
Clinic of Cardiology, RWTH Aachen University Hospital, Aachen, Germany.
Eur J Vasc Endovasc Surg. 2021 Aug;62(2):276-283. doi: 10.1016/j.ejvs.2021.04.001. Epub 2021 May 27.
The impact of stent design on venous patency is not well studied. The purpose of this study was to investigate the effect of stent material burden on endothelial coverage of stented venous segments, which may contribute to vessel healing and patency.
Segmented self expanding bare nitinol stents (18 × 50 mm) comprising 5 mm long attached metallic rings separated by 2, 5, or 8 mm gaps were implanted in the inferior vena cava (IVC) of 10 sheep. These stents were designed and manufactured for the purposes of this study. At six, 12, and 24 weeks after implantation the animals were euthanised and the stented vessels harvested for histomorphometric analysis. Three sections from the metallic part as well as the gaps between the struts were reviewed for quantification of endothelialisation after six, 12, and 24 weeks. The intimal thickness over and between the stent struts was measured. The endothelialisation score (graded from 1 for complete luminal endothelialisation to 5 for absence of endothelial cells) was determined.
All stents were successfully deployed and all 10 sheep survived until the time of harvesting. Macroscopic inspection after 24 weeks showed only partial endothelialisation over stents with 2 mm and 5 mm skipped segments, whereas the stents with 8 mm skipped segments were totally incorporated into the vein wall. After 24 weeks, the mean (SD) neointimal thicknesses over stent struts with 2 mm, 5 mm, and 8 mm skipped segments were 254.0 (51.6), 182.2 (98.1), and 194.6 (101.1) μm, respectively. Comparison of endothelialisation scores of stents over time showed statistically significantly better endothelialisation over stents with 8 mm gaps after 12 and 24 weeks.
Stent designs providing structural support to veins with larger gaps between the scaffold material appear to lead to faster and more complete endothelialisation as well as a thinner intimal layer.
支架设计对静脉通畅性的影响尚未得到充分研究。本研究旨在探讨支架材料负荷对支架静脉段内皮覆盖的影响，这可能有助于血管愈合和通畅性。
将 5 毫米长的附着金属环分隔开 2、5 或 8 毫米间隙的 18×50 毫米分段自扩张裸钛镍诺支架植入 10 只绵羊的下腔静脉（IVC）。这些支架是为了本研究的目的而设计和制造的。植入后 6、12 和 24 周，处死动物并采集支架血管进行组织形态计量学分析。对金属部分的三个部分以及支架之间的间隙进行回顾性分析，以确定植入后 6、12 和 24 周的内皮化程度。测量支架跨壁的内膜厚度。确定内皮化评分（从完全管腔内皮化评分为 1 到无内皮细胞评分为 5）。
所有支架均成功植入，所有 10 只绵羊均存活至采集时间。24 周后宏观检查显示，仅在支架上具有 2 毫米和 5 毫米跳过段的情况下存在部分内皮化，而具有 8 毫米跳过段的支架则完全融入静脉壁。24 周后，支架上具有 2 毫米、5 毫米和 8 毫米跳过段的新生内膜厚度平均值（SD）分别为 254.0（51.6）、182.2（98.1）和 194.6（101.1）μm。随着时间的推移，支架内皮化评分的比较显示，在 12 和 24 周时，具有 8 毫米间隙的支架内皮化明显更好。
为静脉提供结构支撑的支架设计，支架材料之间的间隙较大，似乎可导致更快、更完全的内皮化以及更薄的内膜层。
