Intraoperative duplex scanning of arterial reconstructions: fate of repaired and unrepaired defects

Because unrecognized lesions can cause an arterial reconstruction to fail, duplex ultrasonography was evaluated as an intraoperative aid to assess technical adequacy and provide criteria for which lesions should be repaired immediately versus safely followed.

Since 1990 intraoperative color duplex scanning(7 to 10 MHz linear array probe, pulsed-wave Doppler test spectrum analysis) was used to assess the frequency and severity of residual lesions in 368 patients after carotid endarterectomy (n = 210), infrainguinal vein bypass (n=135) or visceral/renal reconstruction (n = 23). Duplex scan results were categorized as normal or abnormal, with immediate repair of lesions demonstrating both lumen reduction and severe focal flow abnormalities (peak systolic velocity [Vp] > 150 to 180 cm/sec;velocity ratio [Vr] > 2.4). Arteriography was also performed in 81% of lower limb bypass procedures.

Duplex scanning identified technical (residual plaque, stricture) or intrinsic defects (platelet thrombus, distal thrombosis) requiring revision in 37 (10%) of the reconstructions. Infrainguinal bypass had the highest incidence of corrected defects (14%) and adverse events (3%). No adverse events occurred in patients with normal duplex scan results or after carotid endarterectomy. Overall, 76% of identified defects were corrected (carotid, 17 of 24; infrainguinal bypass, 19 of 24; visceral bypass, 1 of 1). Unrepaired flow defects (Vp = 150 to 190 cm/sec; Vr = 1.8 to 2.5) led to one graft occlusion and three early revisions. Postoperative duplex scanning demonstrated residual stenosis in seven of 12 patients with unrepaired defects, two of 36 patients with repaired defects, and five of 312 patients with normal scan results (p < 0.001).

Based on the types of lesions corrected and the low (< 0.5%) complication rate after a normal or modified arterial reconstruction, duplex scanning was found to be a valuable intraoperative aid. Unrepaired defects require close surveillance for progression.