[Proximo-distal course of the diameter of the great saphenous vein and distribution of the number of side branches as an inherent difficulty in infra-inguinal arterial in situ bypass].

The greater saphenous vein is still the best material for infrainguinal arterial bypasses, particularly if they have an infrapopliteal distal anastomosis. Although a lot of advantages have been presumed for the in-situ bypass, the reported results are not significantly better than with the reversed technique. To find some additional explanations, we studied post mortem the anatomy of 20 greater saphenous veins with regard to the diameter and the number of side branches and compared the results with 10 phlebographies. A minimal diameter (2.6 mm) and a maximum of side branches and venous valves were found at the proximal calf. Furthermore, this region was characterized by a lot of anatomic variants such as double systems (25%) or cross over variants (5%). These findings are surgically relevant and may reduce the bypass patency: 1. There is an increased hemodynamic resistance in longer bypasses, 2. The small diameter (particularly if smaller than 2 mm) means a risk for the patency of the distal anastomosis, 3. The high frequency of side branches requires a comparable exposition of the GSV as for the reversed technique, 4. The introduction of the valvulotomy from distally may overestimate the proximal diameter and underestimate the frequency of variants and may therefore cause significant endothelial damages or even perforation.