Wu M H, Kouchi Y, Onuki Y, Shi Q, Yoshida H, Kaplan S, Viggers R F, Ghali R, Sauvage L R
Hope Heart Institute, Seattle, WA 98122, USA.
J Vasc Surg. 1995 Oct;22(4):382-90; discussion 390-2. doi: 10.1016/s0741-5214(95)70005-6.
The purpose of this study was to determine the effects of increased shear stress on the aggregability of platelets as they traverse a long, small-caliber (6 mm) Dacron graft in the dog and on the surface thrombosis and endothelialization of such a graft.
Each of nine dogs received bilateral carotid-femoral artery grafts, approximately 75 cm long, for 3 months; one graft of each pair had a distal femoral arteriovenous fistula to produce a higher shear rate than the contralateral graft. Platelet aggregation scores were determined on blood withdrawn from the external jugular vein and from the proximal and distal ends of the grafts in each animal. Graft flow rates, which were used in the computation of shear stress, and luminal pressure gradients through grafts were measured during surgery and specimen retrieval. Specimens were studied with light microscopy after hematoxylin and eosin and immunocytochemical staining and by scanning electron and transmission electron microscopy to evaluate the nature, composition, and thickness of the flow surface lining, as well as the transmural healing.
Two high-shear stress and two low-shear stress grafts occluded unilaterally; five dogs had bilaterally patent grafts, allowing comparative analyses. All subjects had low platelet aggregability with aspirin. Platelet aggregation scores taken from proximal and distal ends of the grafts were not significantly different. The high-shear stress grafts had significantly more endothelial-like cell coverage (p < 0.0371) than the low-shear stress grafts, less flow-surface thrombus (p < 0.0056), and a thinner surface lining (p < 0.0029), on both the neointima and pseudointima.
In subjects with low platelet aggregation scores, long Dacron grafts do not elevate platelet aggregability of blood flowing through them. High-shear stress grafts have less flow surface thrombus, more endothelialization, and a thinner surface lining than do low-shear stress grafts.
本研究的目的是确定增加的剪切应力对血小板在犬体内通过长6mm小口径涤纶移植物时的聚集性的影响，以及对这种移植物的表面血栓形成和内皮化的影响。
9只犬每只均接受双侧颈动脉-股动脉移植物，长度约75cm，持续3个月；每对移植物中的一个在股动脉远端有动静脉瘘，以产生比对侧移植物更高的剪切速率。在每只动物的颈外静脉以及移植物的近端和远端抽取的血液上测定血小板聚集分数。在手术和标本采集期间测量用于计算剪切应力的移植物流速以及通过移植物的腔内压力梯度。标本经苏木精和伊红染色及免疫细胞化学染色后用光学显微镜研究，并通过扫描电子显微镜和透射电子显微镜评估流动表面内衬的性质、组成和厚度，以及透壁愈合情况。
两个高剪切应力移植物和两个低剪切应力移植物单侧闭塞；5只犬的移植物双侧通畅，可进行对比分析。所有受试者服用阿司匹林后血小板聚集性均较低。从移植物近端和远端测得的血小板聚集分数无显著差异。高剪切应力移植物的内皮样细胞覆盖显著多于低剪切应力移植物（p < 0.0371），流动表面血栓较少（p < 0.0056），内膜和假内膜的表面内衬均较薄（p < 0.0029）。
在血小板聚集分数较低的受试者中，长涤纶移植物不会提高流经它们的血液的血小板聚集性。与低剪切应力移植物相比，高剪切应力移植物的流动表面血栓较少，内皮化程度更高，表面内衬更薄。
