Microvascular grafts: effect of diameter discrepancy on patency rates

This study examined the effects of diameter discrepancy between interpositional vein grafts within a range of 0.25 to 2 mm. One hundred rats underwent isolation of a 10 mm segment of the femoral artery, from which a 4 mm segment was removed. Venous grafts measuring 8 +/- 2 mm were interposed. The rats were categorized by their graft to artery diameter ratios. Patency was assessed upon completion and 4-6 days postoperatively. All surgical specimens were submitted to the pathology department for microscopic evaluation. Results showed Group I: graft to artery ratio 1:1, patency rate 90% (18/20); Group II: ratio 0.75:1, patency rate 80% (16/20); Group III: ratio 0.5:1, patency rate 60% (12/20), Group IV: ratio 0.25:1, patency rate 20% (4/20); Group V: ratio 2:1, patency rate 60% (12/20). It is concluded that 1:1 venous graft to artery ratios are optimal. When this is impossible, diameter discrepancies should be at least 0.75:1 for acceptable patency rates to be attained in microvascular grafting.