Correlation of long-term results of femoropopliteal autogenous vein grafts with shear stress variation. In situ or reversed graft?

To investigate the correlation between blood flow rate and shear stress variation (tau-variation), the integral of time differential of wall shear stress in one cardiac cycle and the outcome of the vein graft, 42 consecutive patients with femoropopliteal autovein grafts (24 in situ and 18 reversed grafts) were followed for 3 months to 5 years after surgical repair. No correlation was noted between the intraoperative blood flow rate and the outcome of the vein grafts with either procedure. In contrast, the tau-variation value of the vein grafts was closely related to their outcome with both procedures. The higher the tau-variation, the better the long-term results. Vein grafts with a tau-variation of over 60 dyn/cm2 showed good long-term results. The in situ grafts tended to have a higher tau-variation than the reversed grafts (67% in the in situ grafts vs 39% in the reversed grafts). Late failures were noted in vein grafts with low tau-variation value within 3 years after surgery. We recommend the in situ graft technique for patients undergoing femoropopliteal reconstruction, with careful follow-up in cases of vein grafts with a low tau-variation value.