Background: Unlike vein bypasses, the role of duplex surveillance of infrainguinal prosthetic bypass grafts is controversial. The purpose of this study was to evaluate the adequacy of color duplex surveillance in identifying failing infrainguinal polytetrafluoroethylene (PTFE) bypass grafts and to assess its value in predicting continued bypass patency.
Method: The surveillance data of primarily patent PTFE bypass grafts were compared with those of revised/occluded PTFE grafts. Ninety-five patients underwent 102 infrainguinal PTFE bypass grafts from January 1991 to December 1996 and were enrolled in a duplex surveillance program at 1 month postoperatively, every 3 months in the first year, every 6 months in the second year, and yearly thereafter.
Results: Seventy grafts remained primarily patent, 5 were revised and 27 occluded. There was no significant difference in the mean age, gender, indication for surgery, type of original procedure, or duration of follow-up between both groups. Four hundred and seven duplex surveillance data were available for analysis. Focal increase in peak systolic velocity (PSV) 3 x the adjacent segment or low flow manifested by PSV <45 cm/sec were considered abnormal. In the primarily patent group, 5 bypasses had abnormal duplex surveillance and were found to have no abnormality on angiogram and remained patent during the study period. In the revised/occluded group, duplex surveillance was abnormal in 8 bypasses. Twenty-four bypasses occluded without any predicting abnormalities on their last duplex examination, which was performed within 3 months from the occlusion in the majority of the patients. In the 27 occluded bypasses, no intervention was necessary following the occlusion in 7 grafts because of mild or no symptoms. Two patients were treated with a primary amputation and 2 had new bypasses. In 16 occluded grafts, salvage of the PTFE bypass was attempted. Ten of these grafts were patent at the end of the follow-up. The sensitivity of duplex surveillance was 25% with a positive predictive value of 61.5%.
Conclusion: Duplex surveillance of infrainguinal PTFE bypass grafts has a low yield and is inadequate at predicting continued bypass patency.