[Critical evaluation of femoro-popliteal-crural in situ venous bypass--experiments on valve elimination and hemodynamics].

In a retrospective study we compared the results of 96 reversed (group I) and of 45 in-situ (group II) femoropopliteal infragenual venous bypasses. All reconstructions were done without TEA of the connecting vessels and without pre-, intra- or postoperative in - or outflow manipulations. The outflow tract (state of the crural arteries) in both groups was similar (p = 0.1). The states of ischemia were different (more cases of limb threatening ischemia in group II, 0.001 less than p less than 0.005). In opposition to most publications the cumulative patency rates were statistically different (88.8%/68.4% after 3 months, 73.1%/25.4% after 2 years, p less than 0.005). Also limited function rates-exclusion of all cases with reocclusion within 3 months respectively all operations with severe faults in indication or technique of operation, showed worse results for the group II (p less than 0.05). Most early reocclusions of in-situ-bypass were caused by leaks of the bypass vein or residual valves. In an experimental study we could demonstrate, that the conventional methods of valve-destruction are followed by an extensive trauma of the venous wall or by an incomplete rupture of the valves. After elimination of the valvular function their afibrinolytic sinus lie free in the vein lumen. We invented and tested experimentally and clinically a new valve-destroying instrument, the Elektrovalvulectome, which does not rupture the valves, but does excise them in toto. Additionally the cutting head of the instrument can be changed in situ and so adapted to the different diameters of the venous conduit. The results were excellent. We found from own hemodynamic measurements and from the literature, that the numerous theoretical advantages of the in situ venous bypass, except the better hemodynamics, are without practical relevance. From our own experiences and those of the literature we must conclude: 1. The in-situ venous bypass is a good method for femorocrural reconstructions. 2. If the distal anastomosis lies in the popliteal artery, we prefer the free orthograd venous bypass. 3. The valves should not be ruptured or incised, but excised in toto.