THE VALUE OF PREDISCHARGE DUPLEX SCANNING IN INFRAINGUINAL GRAFT SURVEILLANCE

Objectives: Protocols and criteria for Duplex-based graft surveillance programmes (GS) vary widely as to the optimum regimens for maximising detection of ''at risk'' grafts. Few centres recommend starting GS before discharge. The aim of this study was to audit our experience with respect to early scanning. Setting: Vascular Studies Unit, Bristol Royal Infirmary. Method: The records of 123 patients entering GS from January 1992 were reviewed. Patients were scanned at 1 week, 6 weeks and 3, 6, 9 and 12 months post-bypass. Haemodynamic criteria used were a peak mean velocity (PMV) less than 45 cm/s and a focal velocity disturbance with a V-2/V-1 ratio of 1.5 or more. Results: Forty-six abnormalities (37% detection rate) were identified on scans within one week. In all cases, on-table completion studies with either auteriography and/or flow measurements had Jailed to identify the anomalies subsequently detected by Duplex. At 1 week, six grafts had occluded, 27 had a focal PMV increase (mean V-2/V-1, ratio: 2.6; range 1.5-4.3), four had low flow velocities, Jour had arteriovenous fistulae, one contained mobile thrombus, two had retained cusps and two had hamstring entrapment. Of 40 patent, but compromised grafts, 18 warranted immediate investigation. Of the 27 patients with velocity disturbances on Duplex, 25 were simply observed but, eight have since required intervention far definitive stenoses at these sites which, in retrospect, were evident within the first postoperative week. Conclusions: Pre-discharge scanning is a useful modality for detecting technical problems. Intrinsic graft abnormalities, possibly the sites of future definitive stenoses, have been visualised even at 1 week and once identified can be more closely scrutinised thereafter Pre-discharge colour Duplex is recommended as standard practice for quality control after infrainguinal bypass.