In situ saphenous vein bypass--forty years later.

In situ saphenous vein bypass, which was performed first by Rob in 1959, but introduced by Hall in 1962, has been widely applied as an alternative to the reversed bypass. Now, forty years later, it seems appropriate to review its current place and technique. Of the presumed original benefits of the in situ operation, it is now clear that the hemodynamic flow of converging (in situ) versus diverging vein (reversed) boundaries plus better vein/artery size match are the main advantages. It is now popular belief that the reversed saphenous vein graft to the popliteal artery has no significant hemodynamic disadvantage because the vein is of comparable diameter at the knee and in the groin. In contrast, vein bypass from the groin to the ankle strongly favors the in situ procedure because of the convergence of the walls of the vein below the knee and better vein/artery size match. The most controversial facet of the in situ operation has been the question of valvulotome is superior to lyse valves and whether to perform the operation open as originally described, or closed to avoid skin complications from a long groin to ankle incision. Preoperative vein mapping is advantageous for all saphenous vein conduit operations. For open leg in situ procedures, skin bridges and incisions made directly over the vein, directed by mapping, will minimize skin complications. Use of endoscopic in situ techniques is ideal but only with an experienced endoscopist. Valve lysis has improved but is still not foolproof.