Prospectively randomized clinical trial to compare in situ and reversed saphenous vein grafts for femoropopliteal bypass.

Two hundred and fifteen femoropopliteal bypass procedures using autologous saphenous vein grafts were randomly allocated to either the reversed or in situ technique. Eleven veins (5 per cent) were rejected at operation on the basis of their small size, nine in the reversed group and two in the in situ group, and there were two (2 per cent) perioperative deaths in each group, leaving 102 reversed and 98 in situ grafts for further study. The cumulative patency at 3 years of the reversed grafts was 77 per cent and that of the in situ grafts was 68 per cent (n.s.). The patency of all grafts was affected adversely by small veins (P less than 0.005), long grafts (P less than 0.05), low volume of blood flow in the grafts (P less than 0.001) and poor run-off (P less than 0.05). These factors influenced the outcome of the in situ and reversed operations to a similar degree and there was no statistically significant difference between them within any subgroup. The mean compliance of the in situ grafts measured 3 months or more after operation with an ultrasonic echo-tracking system was 0.024 +/- 0.01 per cent/mmHg (+/- s.d.) compared with 0.017 +/- 0.01 per cent/mmHg for the reversed grafts (t = 2.43, P less than 0.02). The incidence of fibrous stricture formation as shown by intravenous digital subtraction angiography was 29 per cent in both the reversed and the in situ grafts. The results of the study to date indicate that reversed and in situ vein grafts are equally effective for femoropopliteal bypass.