Intraoperative determinants of infrainguinal bypass graft patency: A prospective study

Objectives:To evaluate a number of currently available methods for intraoperative assessment of infrainguinal bypass grafts (IBG) in terms of detecting technical errors and predicting graft failure.Design:Prospective open clinical study.Methods:Forty-nine patients undergoing 54 consecutive IBG were studied. Intraoperatively, the following measurements were performed: distal pulse palpation (DPP), continuous wave Doppler (CWD), pulse volume recording (PVR), and ultrasonic volume flowmetry (UVF), followed by intraoperative angiography of the entire graft and runoff vessels. The outflow resistance was graded according to the guidelines of the Society for Vascular Surgery and International Society for Cardiovascular Surgery (SVS/ISCVS runoff score). Graft patency was determined noninvasively (PVR, colour Duplex) up to 12 months following surgery. Predictive values and likelihood ratios for the intraoperative tests in detecting a technical problem during the bypass procedure and in predicting early graft failure were calculated.Results:There were five immediate revisions for problems detected intraoperatively. Angiography did not identify any additional problems but assisted in the correct location of the problems detected by the other tests. DPP and CWD were highly significant indicators of the need for revision with likelihood ratios for a positive test of 14.7 (p < 0.01) and 12.3 (p < 0.01) respectively. PVR did not achieve statistical significance in this respect. None of the intraoperative tests was a statistically significant predictor of early graft failure. The SVS/ISCVS runoff score, on the other hand, predicted early failure with a PPV of 33% (likelihood ratio for a positive test of 4.9, p < 0.05). None of the grafts with a perfect SVS/ISCVS runoff score (n = 39) failed in the first postoperative month.Conclusions:Simple CWD insonation of graft and anastomoses is the best intraoperative indicator for technical inadequacies after IBG. Routine intraoperative angiography is not necessary and intraoperative anatomical imaging may be reserved for situations in which noninvasive documentation of technical success is absent. Contrary to the intraoperative haemodynamic test results, the SVS/ISCVS runoff score is a good predictor of early graft failure