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 be fore discharge. The aim of this study was to audit our experience with respect to early scanning. Setting: Vascular Studies Unit, Bristol Ro yal Infirmary. Method: The records of 123 patients entering GS from Ja nuary 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 distur bance with a V-2/V-1 ratio of 1.5 or more. Results: Forty-six abnormal ities (37% detection rate) were identified on scans within one week. I n all cases, on-table completion studies with either auteriography and /or flow measurements had Jailed to identify the anomalies subsequentl y detected by Duplex. At 1 week, six grafts had occluded, 27 had a foc al PMV increase (mean V-2/V-1, ratio: 2.6; range 1.5-4.3), four had lo w flow velocities, Jour had arteriovenous fistulae, one contained mobi le thrombus, two had retained cusps and two had hamstring entrapment. Of 40 patent, but compromised grafts, 18 warranted immediate investiga tion. Of the 27 patients with velocity disturbances on Duplex, 25 were simply observed but, eight have since required intervention far defin itive stenoses at these sites which, in retrospect, were evident withi n the first postoperative week. Conclusions: Pre-discharge scanning is a useful modality for detecting technical problems. Intrinsic graft a bnormalities, possibly the sites of future definitive stenoses, have b een visualised even at 1 week and once identified can be more closely scrutinised thereafter Pre-discharge colour Duplex is recommended as s tandard practice for quality control after infrainguinal bypass.