Postoperative assessment of below-knee bypass grafts.

Our results seem to demonstrate that, even when healthy or arteriosclerotic arteries tolerate knee flexion without any impairment of blood flow, all bypass materials, to a certain extent, have a tendency toward morphologic changes, such as kinking, looping, stenosis and decrease of peripheral blood flow. Reocclusion in below-knee reconstruction, which cannot be explained by poor outflow situation or technical faults, might be related to the graft material used as well as hemodynamic changes caused by flexion of the knee joint. With the use of ASV grafts, these changes are minimal and of little or no clinical importance; when HUV is used, these changes are more distinctive and might, in some instances, be the cause of reocclusion. This could explain the difference in the late results with the use of ASV or HUV. The results of reinforced PTFE still await evaluation. However, it should be kept in mind that the results in addition to the already mentioned influences are also caused by neointima proliferation and progression of the disease.