BIOMECHANICAL FACTORS IN ANASTOMOTIC INTIMAL HYPERPLASIA

内膜增厚是正常愈合反应的特征， 移植物坏死 然而，在外周动脉的移植物中， 吻合口远端增生是导致吻合口狭窄的主要原因。 人工血管移植失败。 药理学努力， 减少小血管内膜增生 至今没有成功。 这种方法并不直接 解决了远端的生物力学因素， 小血管病变或性质的变化， 吻合部位的流场。 血流动力学相关因素 与分支几何形状和与机械性能的 动脉壁与内膜的位置密切相关 增厚和动脉粥样硬化。 血管病变影响 通过改变几何形状、壁面顺应性 以及吻合口周围的运动和流速。 我们的工作假设是吻合口的分布 内膜增厚或增生对应于分布 在流体-壁界面处作用在壁上的剪切应力， 主要发生在低切变和振荡切变区域 应力，即，其中局部颗粒停留时间增加。 我们 因此，建议在狗中构建血管旁路移植物 在不同的吻合几何形状、流动 条件壁特征，如发生在 接受下肢动脉旁路手术的患者， 评估相关机械和 结构因素对局部化和程度的影响 愈合过程中吻合口内膜增厚 过程 为了实现这一点，我们将量化空间 吻合口内膜增厚的分布 辅助三维重建技术， 将这些发现与尺度上的空间分布相关联 壁面切应力和颗粒停留时间的关系模型 几何形状，移植物与动脉顺应性， 周围血管的流速分布。 的 预期调查结果将明确和定量地界定， 这是第一次， 内膜增厚和相应的流场条件， 并确定最佳的生物力学条件， 最小化吻合口内膜增生。

Intimal thickening is a feature of the normal healing response at graft anastomoses. Yet, in grafts to peripheral arteries, intimal hyperplasia at the distal anastomosis is the major cause of prosthetic vascular graft failure. Pharmacologic efforts to minimize intimal hyperplasia in small vessel anastomoses have thus far been unsuccesful. This approach does not directly address the biomechanical factors which prevail at distal anastomoses to small vessels or the nature of the changes in the flow field at anastomotic sites. Hemodynamic factors associated with branch geometry and with the mechanical properties of the artery wall correlate closely with the localization of intimal thickening and atherosclerosis. Vascular anastomoses affect near-wall flow properties by altering geometry, wall compliance and motion, and flow velocities about the anastomotic junction. It is our working hypothesis that the distribution of anastomotic intimal thickening or hyperplasia corresponds to the distribution of shear stress acting on the wall at the fluid-wall interface and occurs principally in regions of lowered and oscillartory shear stress, i.e., where local particle residence time is increased. We therefore propose to construct vascular bypass grafts in dogs under conditions of differing anastomotic geometry, flow conditions an wall characteristics such as those which occur in patients undergoing lower extremity arterial bypass surgery and to assess the effects of the associated mechanical and configurational factors on the localization and degree of anastomotic intimal thickening during the course of the healing process. To accomplish this we will quantify the spatial distribution of anastomotic intimal thickening using computer- assisted three dimensional reconstruction techniques and correlate these findings with the spatial distribution in scale models of wall shear stress and particle residence time in relation to geometry, to graft versus artery compliance and to the distribution of flow velocities in the perianastomatic vessels. The findings would be expected to define clearly and quantitatively, for the first time, the actual localization of perianastomotic intimal thickening and the corresponding flow field conditions, and to identify the optimal biomechanical conditions for minimizing anastomotic intimal hyperplasia.