Stenosis development at the distal anastomosis of prosthetic bypasses for aortoiliac occlusive disease. Incidence and accuracy of colour flow duplex in the diagnosis.

When bypasses for aortoiliac occlusive disease fail they often do so because of a stenosis at the distal anastomosis. To assess the incidence of stenotic lesions and to establish the diagnostic reliability of colour-flow Duplex scanning, we investigated 103 aortoiliac and aortofemoral bypasses using intravenous (i.v.) digital subtraction angiography (DSA) as the reference method. Stenotic lesions at or just beyond the distal anastomosis were identified by i.v. DSA in 30 patients. The stenosis had a 30-49% diameter reduction (DR) in 10, 50-79% DR in 17 and 80-99% DR in three patients. The incidence of stenoses identified within the first 3 years following the operation was 33%, in the period of 3-6 years 20%, in the period of 6-9 years 32% and for bypasses longer than 9 years after the operation 50%. Colour-flow imaging had a 89% sensitivity in identifying the presence and location of distal anastomotic stenosis and a 95% specificity of ruling out significant lesions. A threshold value of 0.65 of the index between the peak systolic velocity (PSV) at a normal vascular segment and the maximum PSV at the side of stenosis demonstrated lesions with a sensitivity of 86% and a specificity of 90%. Prophylactic repair of a high grade stenosis (> 70% DR) was performed in only two patients. Colour-flow Duplex is accurate in identifying distal anastomotic stenoses. Although the precise incidence of these lesions can be determined only by a prospective surveillance study, available data suggests a low yield of cases requiring prophylactic repair.(ABSTRACT TRUNCATED AT 250 WORDS)