Fundamental study on small-diameter vascular graft incorporated with new design concepts of mechanical compatibility and tissue morphogenesis.

为了最大限度地减少人工动脉和人工动脉在整个压力区域的顺应性失配，我们提出了一种同轴双管式人工血管，它由一个增强的顺应性内管和一个不太顺应性的外管组成，两者都是用可控的多微孔分段聚氨酯(SPU)薄膜制成的。首先，将犬颈总动脉的压力-内径(P-D)关系确定为靶动脉，其压力-内径曲线呈“J”型曲线。在具有不同管间间距、微孔密度和壁厚的几种同轴双管SPU移植物模型中，定义并建立了两个决定变量，即每根管子的压力诱导膨胀度和管间间距。轮胎内胎的膨胀性决定了…低压区的膨胀性更多ns，通过壁厚和微孔率进行调整。较薄的薄膜具有较高的孔隙率，导致高压诱导膨胀。另一方面，采用具有较厚壁厚和较低微孔率的外管实现了高压区的低压诱导膨胀性。从低压区到高压区的转换点由管间距离由理论值确定。在这些结果的基础上，我们提出了一种与犬颈动脉具有良好顺应性的同轴双管移植物的原型模型，通过将高顺应性的内管(涂有光反应性明胶和肝素)插入不顺应性较差的外管(涂有光反应性亲水性聚合物)来同轴组装移植物。28个同轴双管顺应性移植物以端到端的方式植入犬的颈总动脉，长达12个月。总通畅率为85.7%(24/27)。无破裂及动脉瘤形成。双管移植物的新生动脉壁由吻合口向管腔表面和肌管间隙重建，早期以肌成纤维细胞和炎性细胞为主，晚期以富胶原细胞外基质为主。用亲水性聚合物涂层防止了外管表面的粘连。虽然植入模型的J曲线在植入后1个月仍保持不变，但后期SPU膜的组织生长、组织粘连和生物降解对植入的同轴双管移植物的力学性能有影响。较少

In order to minimize compliance mismatch between native artery and arterial graft prosthesis over the entire pressure regions, we proposed a coaxial double tubular artificial graft, which consists of an enhanced compliant inner tube and a less compliant outer tube, both of wihch were fabricated using well-controlled multiply micropored segmented polyurethane (SPU) films. Double tubular grafts were coaxially assembled by inserting the inner tube into the outer tube.Firstly, the pressure-diameter (P-D) relationship of canine common carotid arteries, which exhibited a "J" curve, was determined as a targeted artery. Two determinant variables, the pressure-induced distensibility of each tube and the intertubular space distance, were defined and formulated in several models of coaxial double tubular SPU grafts, which had various intertubular space distances, micropore densities and wall thicknesses. Tire distensibility of the inner tube determined the distensibility in the low-pressure regio … More ns, which was adjusted using wall thickness and microporosity. Thinner films with higher porosities resulted in a high pressure-induced distensibility. On the other hand, a low pressure-induced distensibility in the high-pressure regions was realized using an outer tube with a thicker wall and lower microporosity. The transition point from low- to high-pressure regions was determined by the intertubuiar distance using the theoretical values. On the basis of these results, we presented a prototype model of a coaxial double tubular graft that exhibited well-matched compliance with canine carotid artery.The graft was coaxially assembled by inserting the high-compliant inner tube (coated with photoreactive gelatin mixed with heparin) into the less-compliant outer tube (coated with photoreactive hydrophilic polymer). Twenty-eight coaxial double-tubular compliant grafts were implanted into the canine common carotid arteries up to 12 months in end-to end fashion. The overall patency rate was 85.7% (24 / 27). and neither rupture nor aneurysmal formation was observed. The neoarterial wall was reconslructed form the anastomoses into the luminal surface and into the imer-tubular space of the double-tubular graft, mainly with the myofibroblasts and inflammatory cells in the early stage and collagen-rich extracellular matrices in the late stage of implantation. Adhesion was prevented on the surface of the outer tube with the hydrophilic polymer coating. Although the "J" curve of the implanted prototype model was preserved at 1 month-implantation, the tissue ingrowth, the tissue-adhesion and the biodegradation of the SPU films were clarified to affect the mechanical property of the implanted coaxial double-tubular graft in the late stage. Less