Ballyk P D, Walsh C, Butany J, Ojha M
Institute of Biomedical Engineering, University of Toronto, Ont., Canada.
J Biomech. 1998 Mar;31(3):229-37. doi: 10.1016/s0197-3975(97)00111-5.
The role of graft-artery compliance mismatch in the development of distal anastomotic intimal hyperplasia (DAIH) is not yet resolved. Although DAIH develops at all surgically created anastomoses, increased compliance mismatch does not lead to greater hyperplasia formation in end-to-end anastomoses, but in end-to-side anastomoses, it leads to a profound increase in hyperplasia. The current study was undertaken to determine whether suture-induced anastomotic stresses could explain these findings. A large strain finite element analysis of vascular wall mechanics was performed to compare the influence of compliance mismatch on intramural stresses in end-to-end versus end-to-side anastomoses. A novel modelling approach was implemented which includes suture-induced stress concentrations. End-to-end and end-to-side graft-artery simulations were executed using (1) artery (compliance = C = 0.44% kPa(-1)), (2) vein (C = 0.33% kPa(-1)), and (3) Dacron (C = 0.14% kPa(-1)) grafts. Residual stresses due to axial tension were included and the anastomoses were statically inflated to 13.3 kPa (100 mmHg). Elevated intramural stresses were found to exist at both the end-to-end and end-to-side graft-artery junctions; however, in the end-to-end anastomosis, the maximum anastomotic stress was not a function of the graft compliance, whereas in the end-to-side anastomosis, the maximum stress was a strong function of graft compliance. For the 45 degree end-to-side geometry considered in this study, the maximum anastomotic stress concentration obtained using a stiff Dacron graft was more than 40% greater than that obtained using a compliant artery graft. In the end-to-end anastomosis, the Dacron graft led to a less than 5% increase in maximum stress over the artery graft. Therefore, increased compliance mismatch increases stresses and promotes DAIH in end-to-side junctions, but, it has little influence on either stresses or DAIH in end-to-end junctions. Thus, the proliferative influence of increased compliance mismatch on suture-line hyperplasia in end-to-side anastomoses can be explained by the resulting increase in intramural stresses. In addition, since high stresses were found in both geometries, elevated suture-line intramural stresses may be an important proliferative stimulus for intimal hyperplasia formation in all vascular reconstructions.
移植血管与动脉顺应性不匹配在远端吻合口内膜增生（DAIH）发展中的作用尚未明确。尽管DAIH在所有手术创建的吻合口中都会发生，但顺应性不匹配增加并不会导致端端吻合中内膜增生更严重，而在端侧吻合中，会导致内膜增生显著增加。本研究旨在确定缝合引起的吻合口应力是否能解释这些发现。进行了血管壁力学的大应变有限元分析，以比较顺应性不匹配对端端吻合与端侧吻合壁内应力的影响。采用了一种新的建模方法，其中包括缝合引起的应力集中。使用（1）动脉（顺应性 = C = 0.44% kPa⁻¹）、（2）静脉（C = 0.33% kPa⁻¹）和（3）涤纶（C = 0.14% kPa⁻¹）移植物进行端端和端侧移植血管模拟。考虑了轴向张力引起的残余应力，并将吻合口静态充气至13.3 kPa（100 mmHg）。发现在端端和端侧移植血管连接处均存在升高的壁内应力；然而，在端端吻合中，最大吻合口应力不是移植血管顺应性的函数，而在端侧吻合中，最大应力是移植血管顺应性的强函数。对于本研究中考虑的45度端侧几何形状，使用硬涤纶移植物获得的最大吻合口应力集中比使用顺应性动脉移植物获得的应力集中大40%以上。在端端吻合中，涤纶移植物导致的最大应力比动脉移植物增加不到5%。因此，顺应性不匹配增加会增加应力并促进端侧连接处的DAIH，但对端端连接处的应力或DAIH影响很小。因此，顺应性不匹配增加对端侧吻合中缝合线内膜增生的增殖影响可以通过壁内应力的相应增加来解释。此外，由于在两种几何形状中都发现了高应力，升高的缝合线壁内应力可能是所有血管重建中内膜增生形成的重要增殖刺激因素。
