Greisler H P, Joyce K A, Kim D U, Pham S M, Berceli S A, Borovetz H S
Loyola University Medical Center, Department of Surgery, Maywood, Illinois 60153.
J Biomed Mater Res. 1992 Nov;26(11):1449-61. doi: 10.1002/jbm.820261105.
Compliance matching between the host vessel and vascular grafts used for small-diameter arterial replacements is thought to be important for long-term patency. However, currently available grafts elicit fibroplastic reactions, resulting in decreasing compliance with time after implantation. Bioresorbable prostheses elicit ingrowth of myofibroblasts containing abundant contractile elements. This led us to investigate whether compliance of implanted bioresorbable prostheses decreased as a function of time and if the kinetics of change correlated with the progression of tissue ingrowth. Woven polyglactin 910 prostheses (10 mm x 4 mm i.d.) were implanted into adult NZW rabbit infrarenal aortas and replicates were harvested serially through 8 months. Control grafts were implanted, and immediately resected. Dynamic compliance was measured at 1-mm axial increments along each explant using a pulse duplicator apparatus which exposed the harvested samples to realistic pulsatile hemodynamics. Compliance was calculated for proximal, mid, and distal segments of each graft and averaged at each time point by grouping into control (zero time, n = 3), early (1-4 weeks, n = 13), and late (6-36 weeks, n = 9) explant periods. At late explant periods both proximal and distal compliance were significantly greater than mid graft compliance (p < .02 and p < .03, respectively). There was a significant increase in proximal compliance between early and late explant times (p < .01). Measured increases in mid and distal segment compliance over time did not reach statistical significance. Myofibroblast laden tissue ingrowth into the inner capsule followed macrophage phagocytosis and was nearly complete prior to the time that an increase in compliance was demonstrated. Thus since the major histologic episodes precede the change in compliance, these are not likely initiated by this biomechanical change. We hypothesize the graft resorption coupled with the ingrowth of more compliant tissue likely leads to the increased compliance of the graft material.
宿主血管与用于小直径动脉置换的血管移植物之间的顺应性匹配被认为对长期通畅性很重要。然而，目前可用的移植物会引发纤维增生反应，导致植入后顺应性随时间下降。生物可吸收假体引发含有丰富收缩成分的肌成纤维细胞向内生长。这促使我们研究植入的生物可吸收假体的顺应性是否随时间下降，以及变化的动力学是否与组织向内生长的进程相关。将编织聚乙醇酸910假体（内径10 mm×4 mm）植入成年新西兰白兔肾下腹主动脉，并在8个月内连续收集样本。植入对照移植物并立即切除。使用脉冲复制器装置沿着每个外植体以1 mm的轴向增量测量动态顺应性，该装置将收获的样本暴露于实际的脉动血流动力学中。计算每个移植物近端、中段和远端节段的顺应性，并在每个时间点通过分组为对照（零时间，n = 3）、早期（1 - 4周，n = 13）和晚期（6 - 36周，n = 9）外植体时期进行平均。在晚期外植体时期，近端和远端顺应性均显著大于移植物中段顺应性（分别为p < 0.02和p < 0.03）。早期和晚期外植体时间之间近端顺应性有显著增加（p < 0.01）。随着时间的推移，中段和远端节段顺应性的测量增加未达到统计学意义。富含肌成纤维细胞的组织向内生长到内膜囊中发生在巨噬细胞吞噬之后，并且在顺应性增加被证实之前几乎完成。因此，由于主要的组织学事件先于顺应性变化，这些不太可能由这种生物力学变化引发。我们假设移植物吸收与更顺应组织的向内生长相结合可能导致移植物材料顺应性增加。
