COMPLIANCE MISMATCH MAY PROMOTE GRAFT-ARTERY INTIMAL HYPERPLASIA BY ALTERING SUTURE-LINE STRESSES

The role of graft-artery compliance mismatch in the development of dis tal anastomotic intimal hyperplasia (DAIH) is not yet resolved. Althou gh DAIH develops at all surgically created anastomoses, increased comp liance mismatch does not lead to greater hyperplasia formation in end- to-end anastomoses, but in end-to-side anastomoses, it leads to a prof ound increase in hyperplasia. The current study was undertaken to dete rmine whether suture-induced anastomotic stresses could explain these findings. A large strain finite element analysis of vascular wall mech anics was, performed to compare the influence of compliance mismatch o n 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 simula tions 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)) graft s. Residual stresses due to axial tension were included and the anasto moses were statically inflated to :13.3 kPa (100 mmHg). Elevated intra mural stresses were found to exist at both the end-to-end and end-to-s ide graft-artery junctions; however, in the end-to-end anastomosis, th e maximum anastomotic stress was not a function of the graft complianc e, whereas in the end-to-side anastomosis, the maximum stress was a st rong function of graft compliance. For the 45 degrees end-to-side geom etry considered in this study, the maximum anastomotic stress concentr ation obtained using a stiff Dacron graft was more than 40% greater th en that obtained using a compliant artery graft. In the end-to-end ana stomosis, the Dacron graft led to a less than 5% increase in maximum s tress over the artery graft. Therefore, increased compliance mismatch increases stresses and promotes DAIH in end-io-side junctions, but, it has little influence on either stresses or DAIH in end-to-end junctio ns. Thus, the proliferative influence of increased compliance mismatch on suture-line hyperplasia in end-to-side anastomoses can be explaine d by the resulting increase in intramural stresses. In addition, since high stresses were found in both geometries, elevated suture-line int ramural stresses may be an important proliferative stimulus for intima l hyperplasia formation in all vascular reconstructions. (C) 1998 Else vier Science Ltd. All rights reserved.