[Factors which affect long-term patency in femoro-popliteal bypass]

The aim of this study was to investigate how "run off", diabetes, cigarette smoking and early reinterventions influence long-term patency of the "reversed" and "in situ" femoro-popliteal (F-P) bypass grafts.

The study included 1991 patients with "reversed" F-P and 99 patients with "in situ" F-P bypass grafts operated on between 1988 and 1994. There were 153 (80.10%) male and 38 (19.90%) female patients in the group with "reversed" bypass and in the group with "in situ" bypass there were 78 (78.8%) male and 21 (21.2%) female patients. The average age of all patients was 59.04 (27-80) years. Eighty five (44.5%) patients in the group with "reversed" F-P bypass had diabetes mellitus and 43 (43.4%) in the group with "in situ" bypass. One hundred and fifty two (79.68%) patients in the group with "reversed" bypass were cigarette smokers and 80 (80.8%) in the group with "in situ" bypass. In Table 1 patients according to Fontain's classification of occlusive arterial disease are presented. On the basis of angiographic examination all patients were divided into four groups (with patent all 3 crural arteries, with patent 2 crural arteries, with patent one crural artery and without patent crural arteries) (Table 2). All patients were controlled using physical and Doppler ultrasonographic examinations immediately after the operation; after 1, 3, 6 months and then every year postoperativelly. In cases with suspected graft occlusion or any other complication, control angiography has also been carried out. Statistical analysis of the results was performed using chi 2 and Fisher's test.

The patients were followed-up from 3 to 10 years. In cases with patent all 3 crural arteries there was no significant difference in long-term patency between "reversed" and "in situ" bypasses (Fisher's test, P = 0.66; p > 0.05) (Graph 1). In cases with patent two crural arteries, there was no significant difference between groups with "reversed" and "in situ" bypasses chi 2 = 0.25, p > 0.05) (Graph 2). The long-term patency was significantly better in the group with "in situ" bypass if only one crural artery was patent (chi 2 = 4.96, p < 0.05) (Graph 3). In cases with occluded all three crural arteries there was no significant difference in long-term patency between the two examined groups (Fisher's test, P = 0.29; p > 0.05) (Graph 4). There was no significant difference between groups with "reversed" and "in situ" bypasses in patients with diabetes mellitus (chi 2 = 0.01; p > 0.05) (Graph 5). There was also no statistically significant difference between the two examined groups regarding the preoperative cigarette smoking (chi 2 = 0.94; p > 0.05) (Graph 6). However, in both groups postoperative cigarette smoking showed a statistically significant decrease in long-term patency (chi 2 = 66.71; p < 0.01) (Graph 7). The early REDO operations statistically significantly decreased long-term patency in both groups (chi 2 = 34.89; p < 0.01) (Graph 8). The late graft occlusions were found in 60 patients with "reversed" and 23 patients with "in situ" F-P bypasses. Table 3 shows causes of late graft occlusions.

In some cases with pure "run off" "in situ" bypass technique showed better long-term patency. We preferred this technique when "run off" was pure, when diameter of the saphenous vein was small, and when bypass was "long". Diabetes mellitus had no significant influence on long-term graft patency in both groups, as well as regarding preoperative cigarette smoking. However, postoperative cigarette smoking and early REDO operations, statistically significant by decreased long-term graft patency in both groups. The reason was that cigarette smoking was not permitted postoperatively, while in cases with early reinterventions physical screening and ultrasonographic examinations were necessary.