Analysis of suturing techniques in the microvascular anastomosis of vessels of unequal diameter.

A rat model has been devised to study the determinants of microvascular anastomotic patency in the setting of diameter discrepancy. Isogeneic interposition grafts of rat inferior vena cava were used to repair a femoral artery defect (diameter ratio 4.5:1). Three methods for compensating for diameter discrepancy were studied. The anastomoses were explored on postoperative days 3, 7, and 14. By 2 weeks, tapered grafts were shown to result in higher patency rates (p < 0.05) compared with nontapered and spatulated grafts. Hemodynamic, histological, and scanning electron microscopic analysis suggested that turbulence caused by large velocity gradients predisposes to thrombosis. This animal model was shown to be sensitive to experimental hemodynamic alterations and may be useful in elucidating the effect of technical or pharmacological manipulations on patency in the setting of vessel diameter discrepancy.