SURVEILLANCE OF INFRAINGUINAL ARTERIAL BY PASS GRAFTS - IMPORTANCE OFDUPLEX-DERIVED PEAK SYSTOLIC VELOCITY AND ANKLE-BRANCHIAL INDEX IN FEMORODISTAL GRAFT ASSESSMENT

In a prospective study, the efficacy of noninvasive surveillance techn iques including measurement of ABI and duplex-derived velocity paramet ers was studied after 74 infrainguinal arterial reconstructions. A dec rease of ABI greater-than-or-equal-to 0.2 compared with prior examinat ions was considered abnormal. Results of the duplex scan were interpre ted as abnormal when PSV was less than 45 cm/sec or greater than 200 c m/sec or when an interval decrease of greater than 30 cm/sec occured. All patients meeting any of these criteria during the follow-up examin ations were subjected to i.a. DSA. The combination of all duplex veloc ity criteria was significantly more sensitive to identify a failing gr aft than was measurement of ABI (90% vs. 18%; p = 0.00004). When indep endent variables (ABI- and PSV criteria, monophasic curve configuratio n) were entered into a logistic regression multivariate analysis, the model proved to be effective (F-value 5.551; df 4.8; R2 = 0.735; signi ficance 98.03%; p < 0.02) in predicting angiogram findings (dependent variable). ABI measurements (significance 4.75%; p > 0.95) and the pre sence of a monophasic curve configuration (significance 89.58%; p > 0. 1) failed to reach significance in the multivariate analysis. By exclu ding these latter parameters, the statistical power for the model coul d be improved (F-value 1036.57; df 2.1; R2 = 0.999; significance 97.69 %; p = 0.0231): As a result normal PSV criteria indicated normal and a bnormal angiographic findings in 83 and 17%, respectively. A PSV less than 45 cm/sec or greater than 200 cm/sec was suggestive of an abnorma l angiogram in 80% and of a normal angiogram in 20%. The corresponding figures for a PSV interval decrease > 30 cm/sec were 71% and 29%. In conclusion, PSV parameters were found to be measurably more accurate t o identify a failing graft than was measurement of ABI.