Duplex imaging of lower limb arterial bypass grafts.

A non-invasive programme of post-operative surveillance and intervention where necessary is essential to optimise results with arterial reconstruction. We report our experience with duplex ultrasonography in the follow-up lower limb arterial bypass grafts. One hundred and three duplex studies were performed in 58 patients with 59 lower limb arterial bypass grafts. Grafts were visualised throughout their length and haemodynamic characteristics including peak systolic velocity (PSV) were measured. Angiography was performed on the basis of any significant anatomical or haemodynamic abnormality on duplex. All grafts were visualised throughout their length with ease. Satisfactory visualisation of 86% of anastomoses was achieved. PSV was found to be the most easily reproducible haemodynamic index and the best indicator of graft function. PSV had a median value of 79 cm/sec and a range of 51-117 cm/sec in normal grafts compared to 26 cm/sec (range 19-42 cm/sec) in grafts with stenosis. Twelve pre-occlusive lesions which were not evident clinically, 5 within and 7 outside the graft, have been detected. Eight have been treated by transluminal angioplasty. Two grafts with stenosis and PSVs of less than 25 cm/sec had occluded by the time angiography was performed 2 weeks later. Duplex is an excellent, non-invasive, and repeatable method of screening of grafts at risk of failure, allowing earlier intervention with improved secondary patency.