Local haemodynamics of arterial bypass graft anastomoses

One of the main causes of failure of expanded polytetrafluoroethylene (PTFE ) bypass grafts used in the lower limbs is the development of myointimal hy perplasia (MIH). Clinical studies show that higher patency rates can be obt ained with the use of an autologous vein cuff (the Miller cuff) interposed between the graft and artery. The reasons for the improved performance are still unclear, but preliminary studies suggest that the change in local hae modynamics due to the cuff geometry may be the significant factor rather th an the presence of autologous material. If this is the case, then PTFE graf ts can be produced with an integral cuff, i.e. a precuffed graft, with simi lar haemodynamic patterns to that of the Miller cuff. In this paper, two di fferent types of precuffed graft are presented and their flow patterns are compared with those recorded in the Miller cuff and the conventional end-to -side anastomosis. The haemodynamic studies were carried out using opticall y clear silicone rubber models under simulated in vivo pulsatile flow condi tions. Flow structures similar to those observed in the Miller cuff were se en in the precuffed grafts.