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Duplex scan graft surveillance: how often and in whom?

The appropriate postoperative surveillance of infrainguinal grafts remains difficult and controversial topic. This study was undertaken to determine a surveillance protocol that was not only cost effective but accurate in detecting both high risk, early failing grafts as well as following long-term grafts. All patients who had an infrainguinal bypass and a postoperative duplex scan measuring velocities over a 6-year period were evaluated. The demographic data, angiograms, medical records, and duplex scans were evaluated, studied, and compared. There were a total of 116 duplex scans performed on 86 grafts in 61 patients. On the basis of velocity measurements and graft patency, grafts were categorized into four groups. The largest group (59%) were those with normal velocities and long-term graft patency. The other group with normal values (17%) was a subset of grafts that occluded shortly after the scans for no apparent reason. This group of occluded grafts with normal scans was closely scrutinized and analyzed. The other two groups both had abnormal values, one (13%) that detected abnormalities and directed surgical revision while the other (11%) occluded before revision. The duplex scan has allowed the vascular surgeon to carefully evaluate and follow infrainguinal bypasses; however, different grafts require different follow-up.